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  • 1.
    Kalm, Helen
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Acoustic Soil-Rock Probing: A Case Study in Gubbängen2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Soil-rock probing (Jb-probing) is the most common probing method in Sweden. Due to the

    penetration capacity of the Jb-probing it can be performed in both soil and rock. However, the

    capacity also results in inherent limitations and uncertainties, such as the difficulty identifying the

    soil layer sequences of soft soils. In order to attain a more detailed soil layer sequence it is

    necessary to perform complementary probing and sampling methods, an inefficient and

    consequently costly procedure. By instead implementing non-interfering complementary methods

    performed simultaneously as the Jb-probing the method may be rationalized. The so-called

    acoustic Jb-probing method may be a potential complement to the Jb-probing.

    In this thesis a continued study of the acoustic Jb-probing method is performed by means of a case

    study in Gubbängen with the focus on the potential additional information that the spectrogram (a

    visual representation of the frequency spectra) may contain compared to the Jb-parameters alone.

    This was done by obtaining vibration signals during Jb-probing using a triaxle geophone installed

    four meters from the boreholes. Vibration signals were collected from 13 boreholes. The vibration

    signals were then analyzed in time- and frequency domain which were compared to corresponding

    Jb-parameters and classified soil types.

    The results showed that the clay layers held the most promise for discovering additional

    information in the spectrogram, however this does not exclude potential in other soil types.

    Additionally, it was shown that the geophone ought to be fastened in the ground in order to attain

    satisfactory data. Overall, the acoustic Jb-probing method is a favorable way of collecting and

    analyzing data, which with continued development of the operational and computational process

    may be an economical alternative to the conventional method.

  • 2.
    Machado, Beatriz
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Artificial intelligence to model bedrock depth uncertainty2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The estimation of bedrock level for soil and rock engineering is a challenge

    associated to many uncertainties. Nowadays, this estimation is

    performed by geotechnical or geophysics investigations. These methods

    are expensive techniques, that normally are not fully used because

    of limited budget. Hence, the bedrock levels in between investigations

    are roughly estimated and the uncertainty is almost unknown.

    Machine learning (ML) is an artificial intelligence technique that

    uses algorithms and statistical models to predict determined tasks.

    These mathematical models are built dividing the data between training,

    testing and validation samples so the algorithm improve automatically

    based on passed experiences.

    This thesis explores the possibility of applying ML to estimate the

    bedrock levels and tries to find a suitable algorithm for the prediction

    and estimation of the uncertainties. Many diferent algorithms were

    tested during the process and the accuracy level was analysed comparing

    with the input data and also with interpolation methods, like

    Kriging.

    The results show that Kriging method is capable of predicting the

    bedrock surface with considerably good accuracy. However, when is

    necessary to estimate the prediction interval (PI), Kriging presents a

    high standard deviation. The machine learning presents a bedrock

    surface almost as smooth as Kriging with better results for PI. The

    Bagging regressor with decision tree was the algorithm more capable

    of predicting an accurate bedrock surface and narrow PI.

  • 3.
    Brinck, Mårten
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stigenius, Karl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Jet grouting as a method for sealing sheet pile excavations in Swedish conditions: A probabilistic approach2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Jet grouting is a groundimprovement method that creates cemented columns in the soil. The soil isinjected with different pressurized fluids, through the monitor, to replace andcement the soil, often with water cement grout. There are three different commonsystems for ejecting the fluids, the single, double and triple fluid system.The process is performed from the ground surface by drilling to desired depthand then withdrawing the monitor while rotating and ejecting and thus creatinga column. There are many applications for this technique. However, this thesisfocus on using jet grouted columns in formation to seal sheet pile excavationsfrom water.

  • 4.
    Liu, Xiaochen
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Reliability – based analysis of embankment dams2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Embankment dams are widely used as water-retaining structures through the world. Two principal structural failure modes of embankment dams are internal erosion and slope instability. The objective of this thesis is to investigate the feasibility of applying probabilistic methods in embankment dam assessment. Compared to deterministic methods, probabilistic methods considers the variability in material properties and the results are more assessable. Meanwhile, the derived sensitivity factors of the variables can be used to find the most influential one.Through a literature review, it is found that the difficulties in defining a limit state function for the full process of internal erosion for embankment dams hold back the application of reliability-based methods. However, reliability-based methods have been recognized as suitable for slope stability assessment.In this thesis, both deterministic and probabilistic calculations have been performed for a homogenous embankment dam. The deterministic calculation is carried out in Slope/W to first find out the most critical slip surface. The failure probability of this slip surface is estimated by both Monte Carlo simulations in Slope/W and FORM analysis in Comrel. Then, the 34 most critical slip surfaces from Slope/W are chosen to calculate the system reliability with simple bounds and applied integration. The results from the deterministic and probabilistic calculations showed that the studied dam has a higher risk of failure than allowed. In the system reliability calculation, simple bounds gives a wide range, especially the upper bounds. It was found that classification of different slip surfaces into different groups with respect to geometry and material was useful to simplify the calculations. Not much improvement in accuracy of the system probability of failure is found when increasing the numbers (from 1 to 5) of the most critical slip surfaces from each group. Even the combination of 1 slip surface from each group only gives an error of 6.5%. Categorizing slip surfaces before performing a system reliability analysis is a good way for simplification of the calculations. Due to this, the criteria used for categorization of the slip surfaces are of interest. In this work, it was found that the slip geometry in combination with the materials included in the slip surface constitute a possible way forward to do this.

  • 5.
    Osterman, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    The Impact of Fracture Orientation on the Choice of Grout Fan Geometry - a Statistical Analysis2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Water ingress into rock tunnels is a problematic phenomenon – especially in urban areas – as a lowered groundwater table may cause harmful settlements. Furthermore, too much ingress can be an incentive for the environmental court to halt the tunnel process, in order to protect the nature as part of a national interest.Water ingress is normally lowered by injecting a water and cement mixture into boreholes in the rock mass – a process called rock grouting – thus sealing the rock fractures. Very little information and research has been on the subject of how the rock fracture orientation interact with the orientation and geometry of the grouting holes. The purpose of this thesis is to investigate whether or not it is possible and feasible to select a grout fan geometry that will have the most intersections with the rock fractures, based on fracture information gained in an early pre-investigation stage. The suitability of different grout fan geometries will be determined by analyzing the amount of fracture intersections that each geometry has in a discrete fracture network, generated based on data obtained from rock cores in the Stockholm Bypass project. The assumption is that more fracture intersections means a higher chance of sealing the rock mass. The results show that there is no clear difference in number of intersections between the analyzed grout fan geometries, indicating that focus should not be on analyzing the grout fans as whole units, but rather on the scale of individual grouting holes and fractures. This thesis also highlights the importance of monitoring according to the observational method.

     

  • 6.
    Falcão de Queiroz, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    An alarm system for pore pressure measurements in the foundation ofconcrete dams: a case study of Storfinnforsen buttress dam2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Concrete buttress dams are relatively light structures and less demandingon foundations; because of that, they may have problems with upliftforces and horizontal joints in the area of the dam´s foundation maypresent a failure mode through sliding. The Storfinnforsen dam, thelargest concrete dam in Sweden, had its foundation studied recently andthe discovery of sub-horizontal joints in the bedrock led to the necessityof having the safety of the dam foundation to sliding assessed.The safety is dependent on the pore pressure, which can vary throughtime. The implementation of an alarm system to monitor and assess thevalues of the pore pressure is necessary to improve the dam´s operation.In this thesis, a new system on how to define alarm limits for measuredpore pressures is suggested.The proposed alarm system will monitor the pore pressure of the joint,calculate the safety factor against sliding, compare it to the alarm limits ofthe system (adopted from RIDAS) and present countermeasures to theproblem.The analysis and implementation of the alarm system on monolith 42 ofStorfinnforsen showed that it does not comply with the Swedishguidelines with respect to sliding stability, but the measured porepressures are low enough to allow the creation of an alarm system thatwill monitor the pore pressure continuously. Furthermore, thecharacteristics of the local geology exclude any quick development of porepressure allowing countermeasures to be applied.However, further research on the definition of alarm limits for this kindof problem is needed.

  • 7.
    Hosseini, Robabeh
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. RISE -Research Institutes of Sweden.
    Steven, Yalta
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. RISE -Research Institutes of Sweden.
    Application of Dynamic Grouting to Improve the Grout Spread Using Varying Aperture Long Slot (VALS): AN EXPERIMENTAL STUDY2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the past centuries, grouting has been one of the most common techniques in geotechnical engineering to strengthen and seal underground structures. Concerning increasing demands for tightness and cost efficiency, cement-based grout has been one the most frequent used materials. One of the first grouting operations is the work done by Charles Bérigny in France back in 1802 in order to repair a sluice by stabilizing the ground with liquid grout. Several studies have been then conducted in grouting, which have contributed into successful improvement of the grouting operations. The investigations have also extended the understanding of the factors such as choice of materials, choice of equipment, and the applied pressure type and magnitude, etc. that influencing the grout spread in rock fracture systems.

     

    Among the factors, the applied pressure is one of the most significant ones influencing the spread of grout during grouting operations. Grouting at static pressure conditions is the most common method used in field, where in practice the injected grout can only penetrate into the rock fractures wider than 100 µm.

     

    Recent investigations conducted on application of static and dynamic pressure conditions, using Short Slot and Varying Aperture Long Slot (VALS) in the lab have yielded an overall improvement of the grout spread under dynamic pressure conditions rather than the conventional static pressure conditions. However, the efforts conducted are just a beginning, especially in very fine micro factures smaller than 70 µm 

     

    The main objective of this investigation was therefore to improve the spread of grout by dynamic grouting into fractures smaller than 70 µm effectively, which could not be done with grouting at static pressure conditions.  Furthermore, the aim was to investigate filtration and erosion phenomena/ tendency of grout flow during static and dynamic pressure application using Varying Aperture Long Slot (VALS) in the lab. The durations of peak and rest periods used in the experiments were 2s/2s and 1s/5.5s, which were equivalent to 0.25 Hz and 0.15 Hz, respectively. The results of dynamic grouting showed up to 10 times improvement in the volume of passed grout through fracture apertures smaller than 70 µm.

  • 8.
    Jansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nilsson, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Buckling of End-Bearing Retaining Walls in Clay2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The design of back-anchored retaining walls in Sweden has traditionally not included global elastic instability of the retaining wall as a possible failure mode. Eurocode 3 part 5 (SS-EN 1993-5) requires design of steel structural members for retaining walls to assess the risk of buckling if the normal force exceeds 4 % of the critical buckling load of the retaining wall.

    The geological conditions in Eastern Sweden are characterized by the intersection of very hard Precambrian rock and very soft Holocene clays. Thus often ground anchors anchored in rock at a 30-50 degree angle to the vertical plane are used to support retaining walls, resulting in a very high utilization of the ground anchor and a significant normal force in the retaining wall. The threshold value for buckling risk is consequently frequently exceeded and the specific failure mode, of global buckling, is often limiting the use of the structural members in practical design.

    The buckling load can either be calculated using Euler’s second or third buckling mode, or by modelling the soil-structure interaction by a suitable model. Since no such model is specified in the code, the aim of this thesis was to develop a model which takes into account the stabilizing effect of the soil for the calculation of the buckling force and to model the soil-structure interaction with a beam-spring model connected to Winkler springs.

    The model simulations show that the soil has a significant influence on the critical load, especially when the retaining wall base is driven to depths greater than 2 meters below excavation depth. The model simulations suggest that higher utilization, with up to 4 times greater critical load, of the steel members is possible for some specific cases and an idealized design factor is also elaborated.

  • 9.
    Clarin, Viktoria
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    En ansats mot förenklad sprickkartering av borrkärna2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis is the inception of a simplified method for logging fractures in drill holes and comprises an evaluation on whether a simplified method is applicable for projects where the observational method is used and time is a critical factor. The following work is a study based on data from Boliden Mineral AB, acquired from investigations for locating a suitable, low-permeable rock mass for a repository for hazardous waste. Water flow in crystalline bedrock, such as that found in Sweden, is traditionally thought to be most influenced by fracture characteristics like fracture density, aperture, roughness, fillings etc. Moreover, these same characteristics influence the rock mass strength, which is why the characterization of fractures is fundamental for construction in rock. To improve efficiency of fracture logging in projects maintained under the observational method, an evaluation on how well the quantified fracture characteristics work for identification of large-scale water bearing structures was performed. Furthermore, the possibility of decreasing the number of fractures to log and characterize in the core was investigated. 

    The results show no apparent correlations between hydraulic conductivity (K) in test sections and the individually mapped parameters. However, the uncertainties are significant, mainly because of the large sections in which the hydraulic tests were conducted, but also because of largescale features influencing K (e.g. interconnectivity) which are not possible to estimate from core data.  Remote logging of borehole images generally underestimates the quality of the rock mass for the three analyzed boreholes.

    A simplified method with a representative selection of fractures for physical core logging was found to describe the distribution of parameter values well, when compared to a complete physical core log for two drill cores. Clayfillings and high Ja -values are however overestimated when the simplified method is applied which may lead to a more conservative reinforcement measure than necessary. However, more studies need to be carried out to evaluate whether the simplified method can reflect the distribution of parameter values for individual fracture sets. Moreover, additional studies are required to evaluate the robustness of the suggested simplified methods in drill cores from areas of more heavily fractured bedrock than those analyzed in this study.

  • 10.
    Pronina, Elizaveta
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of Real Time Grouting Control Theory Using a Varying Aperture Long Slot- VALS2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main goal of the grouting is to seal the fractures in the rock mass,improve the strength properties of the rock mass and decrease deformability. However,the overuse of the grouting should be avoided due mainly to economic reasons,optimizing the project time and sometimes severe environmental issues.Insufficient grout spread can cause worse sealing results and decreasedurability. To control the process of grouting and predict the penetrationlength an analytical solution called Real Time Grouting Control theory (RTGC) hasbeen developed. This thesis aimed to evaluate RTGC theory on the equipmentrepresenting a one-dimensional model of a fracture called Varying Aperture LongSlot - VALS. The evaluation was based on a comparison between the calculated(predicted) penetration length according to RTGC theory and the realpenetration obtained in the experiments. Results of the tests show that the RTGCtheory is a good tool to predict the penetration length of the grout at thejoints with apertures close to the hydraulic apertures. At the apertures,significantly less than the hydraulic aperture, the results of the test andRTGC theory differ a lot.

  • 11.
    Nilsson, Tobias
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Sofie
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Kapacitetsuppföljning av genomförd spontdrivning2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sheet pile walls is a common type of retaining structure and is today the most time and cost effective solution on the market. Sheet pile walls consist of steel sheet piles which often are driven with vibratory equipment. A number of studies have since the beginning of the 21st century investigated which factors that influence the driveability of a sheet pile. But the knowledge about expected production capacity, for an entire project, is still limited and the only indication for difficulties when piling, that is used today, is the occurrence of blocks and firm friction soil. This leads to uncertainties in the planning phase of project which can lead to delays and increased costs.

    The goal of this work is to enable for estimation of the sheet piling capacity in an early state of projects. The work intends to answer what capacity can be expected when sheet piling and if it is possible to predict this from the parameters evaluated from the soil-rock sounding.

    To fulfill the goal of this work nine sheet piling project performed by Skanska Sverige AB have been studied. Based on information from diaries and sheet piling protocols, from these projects, the capacities of the sheet piling have been gathered. Gathered data for the capacity have then been connected to the penetration resistance evaluated from the soil-rock sounding to find a possible relationship.

    The most significant result of this study illustrates that no relationship between the capacity and penetration resistance from soil-rock sounding can be shown. This lack of relationship can be used as an argument between parties to show that soil-rock sounding is not suitable for calculating expected capacity. There are several possible reasons for this result and one is uncertainties in the information gathered from project diaries. Another explanation can be that soil-rock sounding does not reflect the parameters in the soil which has the greatest significance when sheet piling.

  • 12.
    Pilipovic, Lea
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Riskhantering vid infrastrukturbyggande: En fallstudie från ett vägprojekt inom Förbifart Stockholm, Hjulsta Norra2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A functioning transport infrastructure creates connections that are constantly moving, thus improving the economy. Today, infrastructure is being expanded through large-scale projects to an increasing extent, which increases the interest in planning, execution and management.

    Sweden invests around 100 billion SEK in construction, operation and maintenance of infrastructure each year. In order to make investments more efficient, it is important that solutions, collaboration and leadership go hand in hand.

    Large infrastructure projects involve major risks. When constructing a highway, many employees and work areas include construction machines, cranes and explosives that can affect soil conditions on site. Thus, identification, assessment and prioritization of risks are important in order not to lose the grip on the safety of the project.

    The purpose of the thesis work is to investigate and describe risk management in an ongoing infrastructure project conducted by NCC Infrastructure in Förbifart Stockholm, Hjulsta Norra. By collecting data from literature and on-site information, problems and efficiency opportunities have been compiled. The thesis work can be used to spread understanding that risk thinking is an important part of the pursuit of profitability in a project.

    The study is executed as a degree project. The scope is 30 credits (equivalent to 20 weeks full-time studies), thus limiting the scope of the study in time. The risks chosen from the ongoing project Hjulsta Norra are a limited number that are prioritized as the most important. As a basis for prioritizing risks in the study, a literature survey and interviews were used.

    Limitation of the study is the production phase, which focuses on the risks that arise during the construction process in a major infrastructure project. It is handled from the contractor's perspective. The selection of interviews that have been made is a small part of those involved in the project and the area. Thus, it is not always possible to include all the information and experience that exists. The selected risk process and risk analysis method are simplified and therefore do not show detailed phases that can have an additional effect on the result. Due to limitations, it is not possible to identify and analyze all risks in the project.

    The study shows that risk management is important in major infrastructure projects. This can be a determining factor in how successful planned activities will be for the end result. To achieve success, identification of environmental, technical and organizational risks needs to be done. Another key factor is how cooperation between the client and the contractor works in a project and during the production phase.

    A future development of risk management in major infrastructure projects is proposed to focus on creating a good organization and collaboration between clients and contractors in the construction phase. Risk management should be a natural part of project management. Continued studies should therefore focus on developing a simple and production-adapted risk management system.

  • 13.
    Yederulh, Hulumtaye Kefyalew
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Settlement calculation for lime/cement column improved clay: Analytical and numerical analyses related to a case study2018Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The dry deep mixing method is widely used to improve a soft clay soil to increase the shear strength as well as to reduce the time for consolidation. It is a mechanical mixing process that makes parts of the soil stiffer than its original strength. It is mainly applicable to soft clay or peat soil.

     

    In this master thesis, the objective was set to perform a comparative analysis on the prediction of the settlements of a clay soil improved by lime/cement columns (LCC). The theoretical settlement predictions were made using two analytical and numerical modeling. A case study was carried out on a part of Stockholm bypass project where LCC was applied to improve soft clay for a foundation of a concrete trough. Field measurements of the vertical deformation of the improved soil were performed using settlement plates to compare the analytical and numerical results.

    The first analytical method was performed based on the recommendation of TK Geo 13 (2013) while the second method was performed based on the concept of a composite ground. In the case of the numerical method, FEA was performed using 2D plane strain model in Plaxis simulation. The performance of the geometry and combined matching models were investigated to convert the axisymmetric to plane strain model. The variation in stiffness of the columns were taken into consideration by applying two stiffness values 30 and 33 MPa for the upper and lower half of the column respectively. A preload of 58 kPa was applied on the improved clay soil to simulate the time-dependent consolidation settlement due to the stress addition.

    A comparison was carried out between the results obtained from the analysis and a field measurement. The two analytical methods produced a better agreement with the field measurement regarding long-term consolidation settlement and a reasonable agreement concerning the rate of consolidation. The numerical analysis showed a good agreement with the benchmark concerning both the long-term consolidation settlement as well as the rate of consolidation. The geometry matching model gave a reasonable result regarding correctness of the result compared with the combined matching. Based on the results obtained in this study, the numerical methods had a better agreement with the measurements.

  • 14.
    Wei, Yukun
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Slope stability assessment through field monitoring2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Deterministic methods have been used in geotechnical engineering for a long period, such as slope stability calculations. However, only applying deterministic methods is subjective and imperfect. There is a demand to develop a systematic methodology to link the assessed slope stability and field measurement data, which is also known as inverse analysis and forward calculation.

    Based on the Nya Slussen project, this thesis includes the development of a methodology, deterministic calculation for 4 cross sections using finite element program Plaxis 2D and probabilistic calculation for one section. Deterministic analyses showed satisfying results for all the studied cross sections since their factors of safety exceeded the minimum requirement. In probabilistic design, three parameters were found to have the most uncertainties through sensitivity analysis (undrained shear strength of clay, Young’s modulus of clay and friction angle of fill). Inverse analysis was done by testing different values of them in Plaxis and to try to match the displacement components provided by field measurement. After finding the best optimization for all the parameters, forward calculation gave a final factor of safety. It is suggested that both of the methods should be utilized together for better assessment.

  • 15.
    Larsson, Louise
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Slope Stability Evaluation from a RiskManagement Perspective: Case Study: the Slussen project in Stockholm2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Site characterization and the subsequent determination of soil strengthparameters constitute a significant part of slope stability assessment.Geotechnical engineering is always governed by great uncertainties sincethe soil properties are challenging to estimate for a large soil volume. Nostandardized method exists for evaluation of soil parameters, since eachcountry uses its own methods for evaluation and interpretation of soils.Uncertainties are common in geotechnical engineering and thereforequalitative and quantitative risk management is required for most projects.The evaluation of the shear strength is essential in slope stability, since ithas a great influence on the stability. This report investigates threedifferent methods regarding the estimation of the characteristic value ofthe undrained shear strength in clay for heterogeneous soils. The followingmethods are used: de 7 with the 5 % fractile, the Swedish applicationdocuments with 𝜂-factor regarding uncertainties and the subjectiveassessment of geotechnical engineers by a questionnaire. In the case studyfor this thesis work, three quayside slopes at Slussen in central Stockholmcontaining highly heterogeneous organic clay located beneath gravel filland esker material were analysed to estimate the stability of the slopes. Theresults show that the 𝜂-factor returned the lowest values, the questionnaireresulted in the second highest and 5 % fractile basted on the samplingdistribution on the mean gave the highest values. No correlation could befound connecting the subjective estimation of the shear strength and otherinfluencing parameter. A method with low subjective judgement, that takethe spatial variability and some degree of interpretation uncertainties witha factor would be to prefer.

  • 16.
    Klaube, Maximilian
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spatial Variability of shotcrete thickness2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An  important  task   during  the  construction  process  is  to  validate  the dimensions  and  properties  of  a  given  structure.  The  dimensions  like  for instance the thickness of a construction element should  be measured after finishing  building  it.  The  aim  is  to  compare  the  measured  value  with  the design  value   to  avoid   that   elements  do   not  correspond  to  the  input requirements.  Moreover,  the  measurements  are  helpful  to  analyse  the statistical    distribution    of    the    investigated    geometrical    property    by computing e.g. a histogram, which visualises the dispersion and  enable the calculation of the probability of failure for a specific structure or element.In  this  work,  a  shotcrete  layer  has  been  analysed  in  order  to  provide information  about  the  homogeneity  of  the  shotcrete  thickness  in  a  pre-determined  tunnel  section.  The  calculation  method  is  based  on  two  laser scans,  before  and  after  applying  the  shotcrete.  Due  to  the  construction process, the shotcrete layer will not be totally equal, which might be a safety problem. Especially, when  the shotcrete layer is thinner than  required and hence, the actual variation of the shotcrete must be considered and verified.To determine the statistical distribution, correlograms and histograms have been  computed  for  a  wall  area  in  a  tunnel  in  Southern  Sweden.  The correlogram shows the distance where the values have a correlation to each other  and  usually  this  distance  is  called  scale  of  fluctuation.  For  the  wall section, this scale of fluctuation has been calculated for the length (0.8m) as well  as  the  height  (0.8m).  Compared  to  the  original  sample  distance,  e.g. distance of the rock bolts, the variance for the calculation of the probability of failure might be reduced.

  • 17.
    Domingo Sabugo, María
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Systematic errors in the characterization of rock mass quality for tunnels: a comparative analysis between core and tunnel mapping2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis analyzes the potential systematic errorin the characterization of the rock mass quality in borehole and tunnel mapping. The difference when assessing the rock mass quality refers to the fact that the characterization performed on drilled rock cores are commonly done on-meter length, while the tunnel section can be up to 20-25 m wide. At the same time, previous studies indicate that the engineering geologist tends to characterize the rock mass quality during tunnel excavation with a conservative estimation of the parameters defining the rock mass quality to ensure a sufficient rock support. In order to estimate this possible systematic error produced by the size difference when assessing the rock mass quality, a simulation was performed within a geological domain, representative of Stockholm city. In the simulation, each meter of the tunnel section was given a separate value of the rock mass quality, randomly chosen from a normal distribution representative for the studied geological domain. The minimum value was set to represent the characterized rock mass quality for that tunnel section. The results from the simulation produced a systematic error due to the difference between the geological domain, reproducing the borehole mapping, and the simulated values, representing the tunnel mapping. The results showed a systematic error in the RMR basic index around 15 points in average, which compared to the difference of 5-7 points obtained in Norrström and the Norrmalm tunnels in the Stockholm Citylink project recently constructed, are found to be excessive. However, in the simulation, it was assumed that (1) the results obtained were the same in the bore hole mapping and in the tunnel mapping, (2) with the only difference of the engineer geologist assigning to the tunnel section the lowest RMR basic value, and (3) that there was no spatial correlation between the quality RMR basic index. After analyzing the three assumptions the simulation was based upon, the absence of spatial correlation was found to be the most significative, which indicate that spatial correlation in rock mass quality needs to be included if a more correct value should be obtained.

  • 18.
    Tsegay, Haftom Tesfay
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Vibration caused by sheet pile driving- effect of driving equipment2018Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    In many construction works in urban areas vibratory driving is the most widely used technique toinstall sheet piles. But due to vibration-sensitive equipment and structures the amount of inducedground vibration need to be minimized. Hence, it is important to select appropriate vibratorparameters that will minimize the level of induced ground vibration.The main objective of this thesis is to study the effect of the vibratory parameter eccentricmoment (vibrator displacement amplitude) on the induced ground vibration during sheet piledriving. To achieve the objective, a literature review and a full-scale field test has beenconducted. The literature review was conducted to provide guidance for the evaluation of thefield test results.The field study was performed in Uppsala in June 2018, where a series of six sheet pile drivingtests were conducted, the first three sheet piles were driven with lower vibrator displacementamplitude and the next three with higher vibrator displacement amplitude, but the same drivingfrequency was used for all six sheet piles. Five tri-axial accelerometers were used to measure thevibration amplitude on vibrator, sheet pile and ground.Important findings of the field study confirmed that, driving sheet piles with higher eccentricmoment will induce lower ground vibration and higher sheet pile penetration speed incomparison to driving with lower eccentric moment. Limitations and possible future researchworks are pointed out.

  • 19.
    Vranckx, Alexander
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Effect of heterogeneous densification due to vibroflotation on liquefaction resistance2017Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 20.
    Persson, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Empirical correlation between undrained shear strength and preconsolidation pressure in Swedish soft clays2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The undrained shear strength and preconsolidation pressure are key parameters in describing the characteristics of soft clays. The two parameters both reflect the clay’s structure and state of stress, and hence empirical correlations for undrained shear strength normalized with respect to preconsolidation pressure are widely used to assess soil behavior. The empirical correlations given in the literature are typically dependent on liquid limit, or plasticity index, but some studies have questioned the dependency and proposed correlations constant for consistency limits. Data from geotechnical projects often display a considerable scatter and deviate from established empirical correlations. In this thesis, statistical analyses are performed and evaluated qualitatively on direct simple shear, constant rate of strain and fall cone test data from 146 sampling points with a total of 596 soil samples from Stockholm, Gothenburg and Uppsala. The aim is to investigate the correlation between shear strength and the preconsolidation pressure. The thesis evaluates the normalized shear strength’s dependency on liquid limit, how the data corresponds to Hansbo’s (1957) and Swedish Geotechnical Institute’s (2007) linear empirical correlations, and the correction factor applied to shear strength measured by the fall cone test. The results of the study show that the correction factor typically reduces the shear strength from fall cone tests too much with respect to shear strength from direct simple shear tests. The normalized shear strength’s dependency on liquid limit may be rejected for the fall cone test data. The results for direct simple shear test data however, indicates a correlation with liquid limit. The data scatter is considerable, especially for fall cone test data, and the relevance of describing the normalized shear strength from fall cone test with a linear empirical correlation to liquid limit may conclusively be questioned.

  • 21.
    McCourt, Brendan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Peat Failure in Ireland: A review based on three different case studies2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The main objective of this thesis was to determine how and why peat fails with the aim of reducing the threat caused by this and also for prevention of the occurrence. Peat is a very common soil in both the UK and Ireland so knowing how it fails and how to prevent it is hugely beneficial. To do this three seperate case studies where analysised, all located in Ireland but in different areas, to see if the failure methods had any similarities or differences that could be linked together. The main finding was that therewas not one sole causal factor for all peat slides but instead a combination of different factors; although some factors are more influential than others for example rainfall. A number of solutions where put forward such as a drainage system for the peat slopes and while they are limited, due to most of the factors being of natural origin, they have the potential to reduce the likelihood and frequnecy of failures if properly implemented.

  • 22.
    Asplind, Moa
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Pore water pressure and settlements generated from water driven DTH-drilling: - A field study2017Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    Foundation work can cause damage to adjacent buildings and infrastructure. Drilling is performed in sensitive areas in urban projects and where the ground conditions are difficult. It is important to be aware of the installation effects from drilling. Pneumatic drilling is commonly used in production but hydraulic drilling is advised in sensitive areas. Hydraulic drilling is believed to cause less disturbance in the ground, although there are no available field studies regarding the installation effects induced by water driven drilling.By measuring the pore water pressure and the settlements during the installation of a RD-pile wall the magnitude and extent of the installation effects induced by water powered DTH drilling is investigated in fill material and esker material. The results indicate settlements close to the installed piles in both materials, larger in the esker material. The pore pressure shows both increases and decreases in the esker material, the decreases implies the Venturi effect is present in water driven drilling. The pore water pressure changes are larger at the measurement point furthest away from drilling in the fill material but the settlements are the smallest there. The largest increases of the pore pressure are seen when the hammer flushes water out into the formation and not during drilling.

  • 23.
    Zervens, Mikaela
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Samverkansgrundläggning - en sättningsuppföljning av två objekt i Uppsala2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 24.
    Sunesson, Philip
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Sannolikhetsbaserad dimensionering av sprutbetong: Fördelningar för tjocklek och böjdraghållfasthet2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the probability based methods that may be used when designing a tunnel is the partial factor method. This method adjusts the value of variables with the help of partial factors, which may be calibrated using a reliability-based approach. The Eurocodes provide these partial factors for different materials and structures, such as reinforced concrete. A limitation with the provided partial factors from Eurocode is the lack of consideration for the usage of the concrete.

    This thesis aims to investigate the possibility to derive new partial factors specifically for shotcrete reinforcement, for the failure mechanism of flexural failure. This has been done by means of reliability theory,FORM/FOSM. Flexural failure in shotcrete may occur when the adhesion between the rock and shotcrete is low. Further, the shotcrete has to have the capacity to withstand bending moments from the rocks. To derive the new partial factors, the measured data of thickness and flexural strength of shotcrete in one of Citybanan's tunnels, Norrströmstunneln, in central Stockholm have been used as the basis for the analysis. The data was described by a statistical distribution which enabled the usage of them in the reliability analysis.

    The results showed that a lognormal distribution best described the shotcrete thickness while flexural strength was best fitted by a beta distribution. The results also showed that it is not recommended to use probabilistic methods in design for this failure mechanism unless uncertainties, arising from some of the models and variables used, are reduced. It clearly shows that it would lead to oversizing compared with the design methods used today.

  • 25.
    Berglin, Alexander
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Short-term deformations in clay under a formwork during the construction of a bridge: A design study2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the casting of a concrete bridge deck, the temporary formwork is causing the underlying ground to deform if a shallow foundation solution is used. There are often demands on the maximum deformation of the superstructure when designing the foundation for the formwork.  To keep the deformations within the desired limits, several ground improvement methods like deep mixing columns or deep foundation methods like piling can be used. Permanent ground improvement methods are however expensive, and far from always needed. To reduce the need for unnecessary ground improvements, it is crucial to calculate the predicted deformations accurately during the design phase.

    The purpose of this thesis was to investigate how short-term deformations in clay under a formwork during bridge construction should be calculated more generally in future projects.

    Three different calculation models have here been used to calculate the ground deformations caused by the temporary formwork. A simple analytical calculation and two numerical calculations based on the Mohr Coulomb and Hardening Soil-Small constitutive models. The three calculation models were chosen based on their complexity. The analytical calculation model was the most idealised and the Hardening Soil-Small to be the most complex and most realistic model.

    Results show that the numerical calculation model Mohr Coulomb and the analytical calculation model gives the best results compared to the measured deformation. One of the most probable reasons for the result is that both of the models require a few input parameters that can easily be determined by well-known methods, such as triaxial-, routine- and CRS-tests. The more advanced Hardening soil small model requires many parameters to fully describe the behaviour of soil. Many of the parameters are hard to determine or seldom measured. Due to the larger uncertainties in the parameter selection compared with the other two models, the calculated deformation also contains larger uncertainties. 

  • 26.
    Indgaard, Jo Forseth
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    The Effects of Different Earth Pressure Coefficient at Rest in Triaxial Shear Tests on Clay2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Triaxial shear test is the most accurate test for deciding the undrained shear strength of clay. In every test the ratio between the horizontal and vertical stresses, the coefficient of earth pressure at rest (K0′), has to be decided. It’s widely believed that the choice of this parameter will influence the results, but it’s not known to what extent.

    In this thesis 20 consolidated undrained active triaxial shear tests on clay has been con- ducted with a K0′ at 0.6 and 0.8. The clay was collected with a 54 mm piston sampler at the Norwegian Geo-Test Site in Trondheim, Norway, on depth of 3.0 to 7.8 meters. Besides the triaxial testing, index tests and oedometer tests was conducted on every cylinder to do a gen- eral classification of the clay. The clay has a sensitivity of 9-20, a water content of 35-51 %, a plasticity index of 27-65 % and an over consolidation ratio of 2.6-6.8.

    The consolidation phase of the triaxial test was conducted in five loading steps with a rest time in-between to monitor the amount of pore water expelled at each stress level. The loading steps was 50 %, 75 % and 100 % of maximum cell pressure and thereafter at 50 % and 100 % of the maximum deviator stress. The shear phase was done at a speed of 1.5 % per hour to a total of 10 % axial strain.

    It is not possible to reach an unambiguous conclusion from the results, but the maximum shear strength of tests with a K0′ at 0.8 is 17 % higher, while the total amount of pore water extortion is equal between the two values. The amount of creep in the latest steps is on the other hand smaller for a K0′ at 0.8. This indicates that the soil is handling the stress level better than with a K0′ at 0.6.

  • 27.
    Peeters, Bieke
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Two-dimensional analysis of the failure mechanisms of an embankment supported by rows of dry deep mixing columns.2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 28.
    Tvinghagen, Adam
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Arching Stability in Shallow Tunnels: A comparison between analytical and numerous solutions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 29.
    Ghyate Forsberg, Karima
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ramak, Rogin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Discrete Element Modelling of the Unbound Layer for Slab Tracks on High Embankment2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    According to Swedish guidelines for high speed railways on embankment, the total settlement is limited to 20 mm over a track length of 10 m during the construction service life. The main objective of this thesis was to investigate the deformation in the subgrade (unbound layer) in a slab track, since there are very few studies related to high speed railways on high earth structure, discussing particularly the unbound layer.

    This thesis examined the unbound layer consisting of granular material by using the discrete element method (DEM) software PFC. There was a focus on the material compaction and deformations due to traffic loading. DEM has the benefit to be able to model deformation with due consideration of processes at microscale level.

    Two different particle shapes were tested: balls and clumps. The results showed that the settlements were small, possibly associated to the well compacted material and the simplifications in the model, such as the shape of the particles, absence of particle breakage and the applied traffic load. The clump simulations resulted in less settlements and permanent strains compared to the ball simulations. The higher the embankment the more settlements but less strains were produced for all the three simulations. One interesting parameter to study for the balls simulation was the friction between the particles. Increased friction contributed to less settlement.

    The maximum height of the embankment was limited to around 3,2 m due to time restraints. Simulations for higher embankments are needed to be performed in order to better understand the effect of the embankment height on settlements.

  • 30.
    Benhalima, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of the differences in characterization and classification of the rock mass quality: A comparison between pre-investigation, engineering geological forecast and tunnel mapping in the Northern Link project and the Cityline project2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the construction of a tunnel, the characterization of the rock mass is performed in three different steps, in the pre-investigations, in the engineering geological forecast and in the tunnel mapping during construction. There has in previous work been observed that discrepancies exist between the results from these different steps, with a tendency to assign poorer rock mass quality in the tunnel mapping than in the pre-investigations and in the engineering geological forecast. One example is the work done by Kjellström [1] on the Cityline where the divergence in rock mass quality was analyzed between the different steps. If a divergence exists between the engineering geological forecast and the actual conditions observed in the tunnel mapping, it will influence both planning and budget. It is therefore important that the engineering geological forecast is as close as possible to the actual rock mass conditions in the field.

    The aim of this thesis was, using the case study of the Northern Link, to analyze those discrepancies in the rock mass quality estimated in the characterization and in the classification between the mapping of drill cores, the engineering geological forecast and the tunnel mapping thus complementing the work by Kjellström [1]. The aim was also identifying which parameters included in the Q-system that causes these discrepancies

    The analysis of the results showed that it is difficult to make the engineering geological forecast and the actual mapping match for every single meter, but that the overall correlation between them was good. The methodology used in the characterization and classification in the different phases (drill-core mapping, engineering geological forecast, tunnel mapping) may to some extent explain this divergence. The parameters Jr, Jn and Ja, included in the Q-system were the ones identified as having the largest influence on the discrepancies. In future work, it is recommended that focus is given on these parameters.

    A way to improve future engineering geological forecast for tunnel contracts would be to have a better follow up of the engineering geological forecast and to have standardized guidelines on how to assess clearly the value of the Q parameters in each phase (for the drill cores as well as for the actual mapping). The reduction of those differences would then lead to a better planning and budget management in future tunnel projects in Sweden.

  • 31.
    Alamaa, Angelica
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    High-speed railway embankments: a comparison of different regulation2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Swedish transport administration initiated this Master Thesis project and the aim was to compare regulations for the design of high-speed railways from three European countries: France, Germany and Spain. The reason why this is of interest for the Swedish transport administration is the design of the first Swedish high-speed railway, called Ostlänken. Therefore, a literature study of the regulations and other literature regarding high-speed railway has been carried out. A basic description of railway components, slab track and ballasted tracks is presented.

    Ballasted embankments usually consist of a trackbed layer (ballast onto subballast), and the ultimate thickness of this layer is discussed, as there are a number of methods available to calculate the appropriate thickness, with a number of different design parameters. These design methods results in different trackbed thickness and choosing the “wrong” method might lead to an overestimation or underestimation of the trackbed layer. Constructing a ballastless railway line means that the ballast is replaced by another material, usually a slab made of reinforced concrete or asphalt, and the rail is cast onto this slab. Countries design their slab using different methods. Germany has constructed high-speed railway lines with a slab track solution, generally slabs with low flexible stiffness. France has until recently constructed their high-speed line ballasted but is now developing a new slab track technique, called NBT (New Ballastless Track) and Spain uses various methods.

    It is difficult to compare the regulations, however, there are some factors that at least begin to explain the differences between the countries: the frost hazard, the inherent ground quality, purpose with the railway (mixed traffic, solely passenger traffic, etc.), design parameters (life, axle load, etc.). Furthermore, the settlement requirements, soil classification and bearing capacity are factors that varies from country to country, but the origin for this variation is harder to detect.

  • 32.
    Holm, Daniélle
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Influence of strain rate in CRS tests: A laboratory study of three Swedish clays2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Constant Rate of Strain (CRS) test is currently the most widely used method for determination of consolidation parameters in Sweden. These parameters are used to calculate the probable settlements and behavior of soils. With the Swedish standard strain rate, the duration of a single the test is about 24h, but a higher strain rate would allow for more tests to be performed in the same amount of time. For all clays in Sweden, the Swedish standard for the CRS test suggests a fixed rate of strain that is independent of soil properties, while the North American standard proposes a strain rate that generates a pore pressure ratio of 3-15%. Soil properties such as water content, liquid limit, sensitivity and shear strength vary greatly between different regions of Sweden. It would be beneficial if these properties could be used to find the ideal strain rate for the CRS test. Performing the tests at a higher strain rate, and thus performing more tests within a shorter amount of time, would save both time and money. In this report, 24 CRS tests are performed on three different clays with distinctive properties. Each clay is tested with three different strain rates: the Swedish standard rate of 0.680%/h, a higher rate of 3.00%/h and a lower rate of 0.154%/h. The results are evaluated according to both standards, and are compared and analyzed to determine whether there is any indication that the strain rate can be selected based on the soil properties. The results indicate that the selection of the strain rate is dependent on the soil properties. In addition, the majority of the tests can be conducted with higher strain rates than what is required by the Swedish standard and still manage to lie within the 3-15% limit of the pore pressure ratio, which is acceptable for the North American standard. However, the preconsolidation pressure does rise with increased strain rates, which can generate problems and erroneous results when calculating the settlements. A more extensive testing program with CRS tests and full-scale field tests must be carried out before any recommendation of a higher strain rate can be made. 

  • 33.
    Sandström, Malin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Numerical Modelling and Sensitivity Analysis of Tunnel Deformations in London Clay2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In dense cities, the interactions between all structures, from tall skyscrapers to complex underground tunnel systems, need to be carefully analysed as soon as a new project is considered. This is necessary because of the stress changes in the soil induced by each new construction. Demolishing a building could cause heave at the base of the excavation, deflections in supporting structures and settlements of the surroundings. The behaviour can be modelled in order to predict how large the deformations will be. This thesis investigates the effectiveness of such models. This is done through the application of a parameter sensitivity analysis on models created in Plaxis. The purpose of the analysis is to identify which factors cause discrepancies between the models and the actual displacements monitored on site.

    The project being examined is located in central London. The analysis focuses on the displacements of existing tunnels below the site caused by the demolition of two buildings. An analysis was carried out to investigate the significance of different parameters, of different material models and methods of analysis, of 3D effects and of inaccurate groundwater data. Ground investigations, laboratory tests and published data were the main sources used to collect reliable initial input parameters for the material models. A model was created in Plaxis 2D using the Mohr-Coulomb and the Hardening Soil with small-strain stiffness material models, using two types of undrained analysis. A model using the Mohr-Coulomb material model was created in Plaxis 3D as well. A sensitivity analysis was then carried out on the 2D models to identify which input parameters were most significant to the tunnel displacements. The results were compared to monitoring data and a back-analysis was carried out to produce more accurate results. The initial and adjusted input parameters were also tested on the 3D model. Finally, the groundwater level was altered.

    The results indicate that soil stiffness and effective cohesion are the most significant. Small-strain stiffness is shown to be especially important when analysing small tunnel deformation. The 3D model generally yielded more accurate results than the 2D model, while the groundwater level did not appear to affect the deformations.

  • 34.
    Björkman, Rasmus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Jabbar, Atheer
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Partialkoefficientmetodens applicerbarhet på dimensionering av sprutbetong mot enskilda block: Fallstudie: Citybanan i Stockholm2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Målet med det här examensarbetet var att undersöka hur väl dagens partialkoefficienter för sprutbetong tar hänsyn till samhällets normer och säkerhetskrav vid dimensionering enligt partialkoefficientmetoden. Det brottfall som har undersökts för dimensionering av sprutbetong är vidhäftningsbrott vid god vidhäftning. Vidhäftningsbrottet har undersökts med hjälp av en sannolikhetsbaserad metod benämnd ”First-Order Reliability Method”, FORM. Metoden förutsätter kännedom om sannolikhetsfördelningar för ingående variabler i brottgränstillståndet som i det här arbetet till stor del baserats på provtagningar från projektet Norrströmstunneln i Citybanan.

    Resultatet av undersökningen visar att partialkoefficienterna antar otillåtna värden för dimensionering av sprutbetong på grund av den stora spridningen som råder i framförallt vidhäftningsparametern. Vidhäftningsparametern antog en normalfördelning med medelvärde 0.808 MPa och standardavvikelse 0.319 MPa vid analys av samtliga vidhäftningsmätningar. Spridningen för vidhäftningsparametern har reducerats genom att undersöka gnejs och granit var för sig och genom att ta bort mätningar där dålig vidhäftning i förväg kunnat antas. För granit fick vidhäftningsparametern ett medelvärde på 0.759 MPa och en standardavvikelse på 0.264 MPa. För gnejs fick vidhäftningsparametern ett medelvärde på 0.820 MPa och en standardavvikelse på 0.279 MPa. I den här fallstudien resultera en reducerad spridning för vidhäftningsdata inte i någon avgörande skillnad för beräknade partialkoefficienter.

    Modellen för vidhäftningsbrottet verkar tillsynes inte vara för komplicerad men det existerar samtidigt stora osäkerheter i modellen och ingående variabler gällande laster och bärförmågor. Framförallt okunskapen gällande lastvariabeln gör det svårt att kalibrera relevanta partialkoefficienter med FORM.

  • 35.
    Ahlund, Rasmus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ögren, Oscar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Pore pressures and settlements generated from two different pile drilling methods2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    For piling works in sensitive soil, especially in inner city projects, it is essential to be aware of the available methods and to choose the most suitable method to minimize the risk of damaging existing buildings or endanger the workers at the construction site. Down-the-hole drilling of piles is a relatively safe method and can be separated into drilling with air powered hammers and water powered hammers. This study compares water powered drilling with air powered drilling and shows that the impact on the soil generated by air powered drilling is larger than that from water powered drilling.

    A field study was carried out where 4 piles were drilled, two with air powered DTH drilling and two with water powered DTH drilling. The drilling was carried out in clay resting on an approximately 4 m layer of silt and friction soil. The total soil depth was about 12- 15 m. To analyze the soil influence, settlements were measured at ground level and in depth and pore pressure was measured in the middle of the clay layer. This study distinguished two major problems when drilling through this type of soil. The first is the risk of over-drilling in the friction layer. The second problem is the risk of increasing the pore pressure in the clay. Both these problems were experienced when using air powered drilling but for the water powered case only a small pore pressure increase and no over-drilling was observed. In conclusion, drilling with water has less influence on the soil in the sense that it gives a smaller effect on the pore water pressure and causes smaller settlements.

  • 36.
    Hanke, Patric
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Matini, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Pressometer: En in situ-metod för Sveriges friktionsjordar2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Fältgeotekniska undersökningar är en viktig del av geotekniken och används vid nästan alla byggprojekt för att utreda markförhållanden och skapa underlag för dimensionering av konstruktioner. För att optimera grundläggningsdesign önskas ofta flera fältmetoder eftersom metodernas olika tillvägagångssätt kan resultera i skilda resultat och parametrar, vilka tillsammans möjliggör undersökningar i alla tänkbara jordförhållanden. En metod erkänd utomlands för sin höga tillförlitlighet och användningsbredd är pressometern, en metod som är på väg att glömmas bort i Sverige.

    Syftet med examensarbetet var att studera pressometerns potential och användningsområde i Sverige. Pressometern som metod bygger på radiell expansion och mäter jordens volymförändring genom trycksättning. Förfaringssättet som pressometern belastar jorden på liknar situationen som jorden kommer att utsättas för under byggnation. Pressometerförsök resulterar i metodspecifika hållfastighets- och deformationsparametrar, från vilka särskilda beräkningsmodeller för uppskattning av bärförmåga och sättningar har utvecklats. Målet var att förse svenska geotekniker med en referens för att förhålla sig till pressometerresultat och -modeller.

    Ett intressant område för pressometern i Sverige är friktionsjordar där ett behov av pålitliga in situ-metoder har identifierats. Beräkningsmodellerna baserade på pressometerresultat har utvärderats och jämförts med beräkningsmodeller för hejarsondering vilken är en vanlig sonderingsmetod i friktionsjord. Vidare har empirisk data från projekt där båda metoderna använts, analyserats och empiriska samband utvärderats mellan dem. Beräkningsmodellerna tolkades sedan mot det empiriska sambandet. Slutligen utfördes ett fältexperiment med de båda metoderna, som tyvärr misslyckades.

    Dataanalysen visar på ett tydligt empiriskt samband mellan hejarsondering och pressometerförsök, dock grundade sig den empiriska analysen på endast 14 observationer och hög standardavvikelse iakttogs. Beräkningsmodellerna för vardera metod visade sig skilja markant. Gällande beräknad vertikal bärförmåga kunde visas att för konstruktioner med stort relativt grundläggningsdjup beräknas den vertikala bärförmågan högre med pressometermodellen än hejarmodellen. För sättningsberäkningar ger pressometermodellen gynnsammare uppskattad sättning vid ökad plattbredd än hejarmodellen.

    Sammanfattningsvis visar studien på att pressometern har ett tydligt användningsområde i Sverige med bra beräkningsmodeller men att klara regler och normer saknas och borde förtydligas. Pressometern är en in situ-metod som i praktiken kantas av problem i utförandet men att den teoretiska grunden och behovet av verklighetsnära fältmetoder ändå skapar utrymme för metoden i svenska friktionsjordar.

  • 37.
    Thorbjörnson Lind, Thomas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rockfalls from rock cuts beside Swedish railroads: A full scale fieldtest, to investigate rockfalls and how rock bounces2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rockfalls is a major problem around the world, if they occur in populated areas, they can cause major damage to infrastructure, injure or kill people. For this reason, it is important to be able to predict where the risk of rockfalls and how to prevent and protect populated areas from them. However, it is no easy task to predict rockfalls. Although if an area with potential area for rockfall is localized it may seem easy to construct protective meshing or bolting potential blocks down. But in many cases this is not easy to do due to practical issues or economic reasons, for example in rock cuts on older railways in Sweden. Fall heights from rock cuts like that are not particularly high but the risk of damage to the trains and infrastructure in the track area is high, however, it is unknown how extensive the damage may be. Trafikverket, the Swedish authority responsible for Sweden's roads and railways, has for some years investigated a new method for classifying and minimize the risk of rockfalls from rock cuts next to the railways. This study include aims to include the potential maximum distance of a block from the rockfall can travel to the existing method.

    This master's work is part of the investigation and will include full scale field test where the rockfalls are examined by filming them and then evaluate the “bounce coefficient”, coefficient of restitution, from the individual rockfalls using photogrammetric methods. During the field study, a geotechnical testing equipment, DCP test rig, to be evaluated for its ability of an easy way in the field to produce an estimated value on the coefficient of restitution. During the evaluation, two rockfall simulating software be used to investigate how well the results from them match the true blocks movements.

  • 38.
    Alcalá Perales, Diego
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. UPV.
    Spatial variation in uplift pressure and correlation with rock mass conditions under two buttress dams: A case study of Ramsele and Storfinnforsen dams2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Uplift water pressure is one of the dominating forces with signicant impact acting on a dam. It is usually measured with piezometers installed along the dam. However, the value of the pressure along the dam is often hard to measure due to the limited number of piezometers available (Bernstone et al., 2009). Furthermore, uplift pressure can oscillate substantially in a single hole both with time and also spatially under the dam due to the combination of rock mass characteristics in the foundation, loads and temperature variations.There is still a lack of information regarding the magnitude and variation of the uplift pressure. The aim of this thesis is to investigate the spatial variation of the uplift pressure based on uplift pressure measurements taken from Storfinnforsen and Ramsele dams. The aim is also to investigate how the uplift pressure depends on the rock mass conditions. The two dams Storfinnforsen and Ramsele provides a unique opportunity due to the signicant amount of piezometers, 270 in total, installed along the rock foundation for the new monitoring programme at the monoliths of both dams.Based on the measured uplift pressure, a probabilistic distribution has been assigned to the uplift pressure. In addition, a possible correlation between the rock mass quality and the uplift pressure as well as the joint aperture and the uplift pressure was analysed.

  • 39.
    Resare, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Analysis of an Inclined Pile in Settling Soil2015Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    The use of inclined piles is an efficient way to handle horizontal forces in constructions. However, if the soil settles the structural bearing capacity of each pile is reduced because of induced bending moments in the pile. There are several reasons for a soil to settle, e.g. if an embankment is built on top of a clay settlements will occur. There is currently no validated method in Sweden to analyse horizontal loading from a settling soil. In the current report a non-linear 3D finite element model is validated by a previously conducted field test and the results are compared to three different beam-spring foundations. These consist of a standard model where a subsoil reaction formulation is used, a model where the soil is considered as a distributed load, and a model with a wedge type of failure. Furthermore, a parametric study is conducted for a cohesionless material where the weight and friction angle of the soil material is varied. The standard soil reaction model yields an induced bending moment almost three times larger than the one obtained from the field test and the two other calculation methods. The latter beam-spring models should therefore be considered in practical design. These findings imply that inclined piles can be used in a far greater extent than previously expected, hence decreasing the cost for the project.

  • 40.
    Gustafsson, Veronica
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Creep deformation of rockfill: Back analysis of a full scale test2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the purpose of studying the mechanical properties of uncompacted rockfill and the creep deformation behaviour of rockfill under a load as well as finding a suitable method for estimation of creep deformation behaviour, a full scale embankment loading experiment was performed. The results of this experiment were then evaluated.

    During the course of this study it became evident to the author that the deformations which were seen in the collected data from the experiment could be classified as creep deformations due to the linear decrease of the deformation against the logarithm of time and the study therefore came to focus on creep. One constitutive equation and one model for estimation of creep deformations were studied, and parameters were obtained through back analysis of experiment data as well as calculation of soil stresses.

    The creep model was based on a logarithmic approximation of the creep deformations and the creep equation was based on a power function. The creep model could also be simplified and evaluated as an equation and when a comparison was made between the equations and the measured results this showed that the logarithmic equation resulted in estimates closer to the measured deformations than what the power function did, therefore a logarithmic function is a better approximation to the deformations of the rockfill at Norvik than the power function.

    When the creep model was evaluated as intended, based on the soil stresses, the resulting creep estimates were less accurate, they was however still within the limits of what can be considered as admissible.

    The conclusion is that a logarithmic function describes the creep deformation of the rockfill at Norvik better than a power function and that the creep model by Kristensen is suitable for estimating the creep deformations. This since the creep model also provides a way of estimating deformations occurring under stress conditions other than the ones for which the creep test was performed.

  • 41.
    Ali Akbar, Saman
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Al-Naddaf, Manar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluating and Comparing of Three Penetrability Measuring Devices: Modified Filter Pump, Modified Penetrability Meter, and Short Slot2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rock grouting is a commonly used process for sealing rocks in tunnels to reduce water ingress. In order to achieve sufficient sealing level the grout must effectively penetrate into rock fractures while the limiting factor is filtration of cement based grout. Many devices and measuring methods have been developed to study filtration and to measure the penetrability. The filter pump and the penetrability meter are two of the most commonly used instruments for measuring filtration tendency in the field and in the lab, while short slot is used mainly in the lab. The results obtained from these devices have relatively different estimations of the penetrability partly due to the weaknesses in measuring methods and test procedures. Furthermore, there are no clear criteria to find out which of the results are closer to the reality or how much the results differ among these instruments. The aim of this study is comparing, and evaluating the results of these devices in relatively similar conditions while using more accurate methods of weight-time and pressure-time compared to the less reliable total volume method. The filter pump and the penetrability meter were modified In order to fulfill the requirement of testing in similar conditions and to improve their accuracy and versatility.

    The results show that increasing the pressure improves the penetrability significantly. The modification of the filter pump results in reducing many uncertainties related to the testing procedure. Probably the modified filter pump has higher accuracy in measuring the penetrability compared to regular filter pump. The short slot has the highest accuracy in estimating penetrability of cement based grout especially at higher pressures, furthermore, the short slot provides a more flexible way to measure penetrability with different pressures in the range of 1-15 bars.

  • 42.
    Neshati Sani, Mehran
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of "GIN method" at Two fans of City banan project in Stockholm2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An underground installation with too much inflow can lead to dangerous consequences for around environment, therefore a well-sealed construction results in appropriate inflows. To mitigate movement of ground water table in underground constructions, it is necessary to seal the rock mass by grout injection. To fulfill the inflow requirement, cement based grouting is both practical and economical solution and is used in Sweden as permanent solution because of the good quality rock mass of Nordic countries. To achieve an effective and more economical grouting process, the method of stop criteria named GIN has been developed for underground constructions.

    "GIN method" is a method in formulating grouting works which provides possibility for minimizing the risk of hydro fracturing and hydro jacking in grouting process to optimize it in performance and cost of construction process. In this report the effort is testing the validity of this method in City banan project which is situated in Stockholm. Data are taken from the City banan project which is under construction by Traffikverket in Stockholm. To attain this aim, data from monitoring of grouting process was collected and Pressure and flow values were obtained and have been employed as input data in this report. After applying GIN method, results have been analyzed and discussed in detail. It has been shown that in studied cases, the theory cannot provide promising results and this method is difficult to be applicable in this project. Therefore, additional tests are needed to the exact suitable GIN number for the project.

  • 43.
    Nikolaev, Simon
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of high pressures in grouting using RTGC - a case study2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The “Real Time Grouting Control Method” is a concept for governing the grout spread during a grouting operation. The goal is to be able to use the penetration length as stop criterion and to be able to monitor the progress of the grouting operation in real-time, which would make grouting operations more efficient in terms of time and cost. The theory has been tested with data from tunnelling projects in Sweden with pre-cambium rock, and with data from dam projects in Iran and in Laos with sedimentary rock, all with promising results. Recently there have been developments in the RTGC-theory that propose jacking limits based on a combination of grout pressure and spread of grout, both for elastic jacking, where deformations can be compensated for, and ultimate jacking, where deformations are permanent. With the theory, the effects of high pressures and elastic jacking can be assessed, and the negative consequences of elastic jacking can be quantified. Specifically, the  focus is on the effect that fracture deformation may have on the distance that the grout penetratesinto a fracture, and on the transmissivity of a fracture. The aim of this thesis is to evaluate what effects high grouting pressures may have on the grouting process with respect to jacking. To obtain this, the theory is used to analyse data from a railway tunnel project in Norway, where considerably higher grouting pressures than in Sweden are used. The application of the theory has been successful, even though some minor adaptions have been necessary. The reason for the adaptions is that the RTGC-theory is developed for a more or less constant grouting pressure, while a varying pressure to some extent has been applied in the Norwegian project. The results suggest that using RTGC could save time and money by reducing grouting time and grout volume. The results also suggest that the high grouting pressures may cause considerable jacking if the geology and fracture situation is unfavourable. If and to what extent the jacking affects the final tightness of the rock mass has however not been possible to determine, given that data regarding measured leakage has not been available at the time for this analysis. It is shown that despite assumptions and simplifications in the geological model, using this theoretical approach enables the estimation of the effect that the grouting pressure has on the outcome of the performed grouting, arguably allowing for the optimum grouting pressure to be selected.

  • 44.
    Mentesidis, Anastasios
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Experimental Evaluation of the Effects of Dynamic Pressure on Improving Cement-based Grout Penetrability: A study performed with the short slot2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasing need for watertight underground works, such as tunnel excavations, has sparked an interest in a number of research studies with grout penetrability being the focus. The research has so far contributed to a deeper understanding regarding the assessment of a successful grouting operation from different perspectives such as choice of equipment, material properties, phase planning and performance. 

    It is well established that several crucial factors influence the penetrability of grouts with pressure type and magnitude being two of them. Researchers have examined this issue from different perspectives and with different instruments. Previous research has shown that the increase of pressure has yielded better grout penetration both in the laboratory and the field. According to studies that dealt with dynamic pressure application, superimposed oscillatory pressure of high frequency resulted in grouts with decreased viscosity and better penetration. However, there is still need for further investigation in terms of lower frequencies, different pressure profiles and magnitudes and possible alternatives regarding the filtration and erosion mechanism.

    The present study aims to examine the penetrability of grouts under dynamic conditions of predefined peak and rest pressure intervals with frequencies lower than 0.5 Hz. The mechanism of action assumes active decomposition of any partially built plug in the vicinity of a narrowing in a rock fracture caused by the change in flow type before the constriction.

    The chosen method included the development of a laboratory grout injection system with a pneumatic valve and a pressure control rig. Tests were performed with both constant and varying pressure utilizing different periods of peak and rest intervals. The results showed an overall improvement of penetrability under dynamic conditions compared to the static. The decrease in peak – rest durations from [2 – 2] to [4 – 8] s yielded almost 11 times more material penetrating the 30μm aperture size. 

    The developed method utilized a pneumatic injection system which culminated in better penetration when tuned at [2 – 2] s of [peak – rest] durations with specific material properties. This study presents an indication that further research towards the direction of dynamic pressure application could be proven beneficial in the grouting industry.

  • 45.
    Carlsson, Martin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Förstärkning av betongdammar med slaka bergbultar: en studie av bultars samverkan med bergsprickor2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Internationally, the majority of dam failures that have occurred are related to the foundation. It is usually linked to the large uncertainty in the actual propertys of the foundation. A common measure was to install rock bolts as an extra precaution in the subgrade to handle the uncertainties of the subgrade.

    In Sweden, most of the hydroelectric dams were constructed between 1940 and 1960. It was not uncommon that cemented reinforced rock bolts were installed in the subsoil as an extra precaution. When these rock bolts were installed, understanding of their stress handling was limited, considering the fact that the theory of the rock bolts behavior was first studied between 1970 and 1980.

    The first part of this thesis is a thorough review of the literature which focuses on the research that has been conducted on the fundamental behavior of the rock bolt when it fails. In this study, a computational theory describing a rock bolts load contribution to a rock joint is presented, verified against experimental shear tests performed on rock bolts.

    In the design of rock anchoring to the construction of reservoirs in the present application RIDAS, Power Companies' guidelines for dam safety, the guidelines is formed by the Swedish dam owners. Accordingly to RIDAS where there is only a risk for a slide in a rock joint stainless untensioned rock bolts are allowed to be used fore support and dimension according to BBK, Boverkets handbok för betongkonstruktioner, kap 3.11 "kraftöverföring genom fog".

    Using the theory presented in the literature review, a stability analysis of a monolith on Långbjörn PowerStation was carried out. The goal was to explore the possibility of rock bolts installed in the subgrade to interoperate with a rock joints under the dam building. The load contribution of rock bolts and the rock joints has to overall stability is compared with the requirements of the Swedish power company’s guidelines for dam safety, RIDAS.

    At the end of the thesis, the presented theories’ applicability under different conditions and how a rock anchor should be designed to be as efficient as possible is discussed. In conclusion, suggestions for research that can be performed on bolting, to gain better understanding of the fundamental behavior of the rock bolt are presented.

  • 46.
    Vazquez Borragan, Alejandro
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Modelling internal erosion within an embankment dam prior to breaching2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There are still uncertainties in the safety of existing embankment dams. For instance, the majority of embankment dams in Sweden were built between 1950s and 1970s, designed and constructed to standards that might be unacceptable nowadays. Particularly, Vattenfall’s records stated that 40% owned embankments dams developed sinkholes (Nilsson, 1999). Moreover, internal erosion and its failure mechanisms of initiation and development are still not fully understood (Bowles et al., 2013). Also, internal threats are difficult to detect and interpret even using new instrumentation techniques. The aim of this Master Thesis is to identify failure mechanisms of embankment dams prior to breaching and hence, verify the reliability of a risk analysis after the breaching of the dam. The methodology consisted of monitoring an embankment dam prone to fail by internal erosion mechanisms. Finally the results were modelled using FEM to identify the risk of internal erosion prior to breaching.

  • 47.
    Wängberg, Alexander
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Partialkoefficienter för stabilitetsanalys av betongdammar2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In Sweden today there are a large number of dams and nearly half of Sweden's electricity is produced from hydropower. The safety requirements on the dams are high due to the consequences that a dam failure can cause. There are several design methods to achieve the expected safety requirements. The design guidelines used in the stability analysis of concrete dams in Sweden is based on the deterministic methods with safety factors. However, a new proposition for design guidelines based on probabilistic methods is being developed. Compared to the deterministic approach the probabilistic method takes into account the uncertainties in individual variables, which are expected to provide more efficient structures.

    One problem with stability analysis using probabilistic methods is that it can be very time consuming. Another method which combines the simplicity of the deterministic approach with the effectiveness of the probabilistic method is the use of partial factors. The use of partial factors is a semi-probabilistic method that can be calibrated from the reliability analysis in the probabilistic method and applied to the individual variables and parameters in the system similar to the safety factor.

    The aim of this thesis was to investigate if stability analysis of concrete dams with partial factors can be an alternative to the methods already available. The report can be divided into three parts. The first part of the report describes the theory behind the calibration process of partial factors using the first order reliability method, FORM. The second part describes existing Swedish methods and application guidelines for stability analysis of concrete dams. The knowledge from the first two parts is then used in order to calculate the reliability of 15 of Sweden's dams. It should be observed that the work contains some limitations, for instance only the sliding stability is studied using one static load case. The results from the calculation of this load case are then used to calibrate the partial factors.

    The result shows that it is not recommended to use the partial factors for stability analysis of concrete dams, at least not with the information and knowledge available today in the field. The uncertainties surrounding certain models and variables need to be reduced in order for partial factors to be an option. The theory behind partial factors requires a certain degree of uniformness when it comes to the structure or elements used. The difference among the dams analyzed in this study may have impacted the results negatively.

  • 48.
    Kardan, Caesar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Quality of CPTU: Analyses and comparison of data from commercial actors in Stockholm/Mälardalen2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    CPTU is one of the most sophisticated geotechnical investigation methods. However, there is a large amount of uncertainties related to this method. The uncertainties depend on different types of factors, for instance lack of accuracy in performance and equipment.

    The objective of this master thesis is to compare the CPTU-results from a number of commercial actors in Stockholm/Mälardalen in order to analyze these results with respect to the current standards and guidelines. The comparison was made in order to highlight the difference in results which may appear due to different equipment, performance of the operator and evaluation method.

    Based on this, an invite was sent to the commercial actors in Stockholm/Mälardalen, resulting in the participation of five different commercial actors in this investigation. Execution in the field was conducted over a six week period. During this time 26 CPTU were performed in total in a small area in Hagby, Stockholm, by these different actors. Once the data was collected from all of the actors, the results were evaluated with the aid of the computer softwares Conrad and Excel.

    The main conclusions from this study are: Not one of the performed CPTU in this master thesis fulfills the requirements for CPT class 1 according to the European standards. The quality of the education of operators should be improved and geotechnical engineers and the clients need to be more familiar with CPTU. The evaluated results from different commercial actors differ, and this can depend on the choice of equipment and performance of the operator during penetration, but it can also depend on systematic errors in the cone penetrometers

  • 49.
    Amin, Diyar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Triaxial testing of lime/cement stabilized clay: A comparison with unconfined compression tests2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis presents results from a laboratory study on a clay from Enköping which was stabilized with lime and clay. Isotropic consolidated undrained compressive tests were performed on samples and compared to unconfined compressive testing.

    The two methods have shown no difference in the evaluation of undrained shear strength. However the modulus of elasticity was shown to be much higher for the triaxial tests. For the unconfined compressive tests the relation between the undrained shear strength and secant modulus was within the range of 44-146. The equivalent for the triaxial tests was in the interval of 112-333. However no pattern was extinguishable between the two tests as this relation has varied between 1,0 to 3,5.

    A lower and higher back pressure was used during the triaxial testing. However, both back pressures have succeeded in saturating the sample. Results show that the back pressure has little effect on the results, as long as the sample has been fully saturated.

    In addition to this extension tests were performed on samples as well. The tests performed were isotropic consolidated undrained. However two different shearing methods were used. The first test was strain rate dependant while the second test was stress rate dependant. In the first test the vertical stress decreased while the radial stresses were kept constant, while in the other test the radial stresses increased while the vertical stress were kept constant.

    The undrained shear strength was compared to lime/cement column penetration tests in field. Results showed that tests in field show a much higher undrained shear strength than laboratory testing.

  • 50.
    Kjellström, Ingrid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Utvärdering av skillnader vid karaktärisering och klassificering av bergkvalitet: En jämförelse mellan förundersökning, prognos och byggskede i projket Citybanan2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was carried out in cooperation with the Swedish Transport Administration and analyzes the possible causes of differing rock mass quality assessed in boreholes, engineering geological forecast and tunnel mapping. Two contracts from the City Line project where investigated - in total has 4596 meters (the Norrström tunnel) and 2557 meters (the Norrmalm tunnel) of tunnel mapped during construction been analyzed. The purpose was to identify the reason and where differences in the process of rock evaluation arose.

    The performed study indicates that in the two investigated tunnels it arose a difference in the results between the characterization performed in boreholes and the subsequent geological forecast compared with the characterization in the tunnel. The assessed rock mass quality became generally successively poorer as the process progresses. This was particulary the case when comparing the geological forecast with tunnel mapping during construction The differences corresponded to a difference of a downgrade of 5 (for the Norrström tunnel) and 7,5 units (the Norrmalm tunnel) in the RMR-system from bore holes to tunnel mapping.

    The analysis of the evaluated results indicates that the differences between the characterization of boreholes and geological forecasts compared to the characterization and classification performed in the tunnel is probably due to the methodology in the characterization and classification of rock quality with the RMR- and Q system. This is because the parameters of the  ystems is not determined exactly in the characterization of the preliminary investigation stage and the characterization and classification in the construction stage. Also the instructions for mapping routines for the characterization and classification are handled differently by the mapping made by geologists during tunneling.

    Based on the results of the analysis it is recommended that the way in which some parameters in the systems of characterization and classification of rock are determined should be updated. This is in order to standardize the process for characterizing the rock mass when mapping boreholes, creating geological forecast and conducting tunnel mapping. It is also indicated  that geologists tend to conservatively scale down the rock quality in the tunnel and that certain features of the rock is easier to determine in the tunnel than during characterization of bore holes.

    By harmonizing the description of parameters of the systems used in the characterization of bore holes and characterization and classification in the construction stage, differences between the steps can be reduced for projects in the future.

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