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  • 1.
    Abbasiverki, Roghayeh
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Seismic response of buried concrete pipelines subjected to highfrequency earthquakesIn: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
    Abstract [en]

    Buried pipelines are tubular structures that cross large areas with different geological conditions. During an earthquake, imposed loads from soil deformations on concrete pipelines may cause severe damages. In this study, the use of two-dimensional finite element models of pipelines and surrounding soil for simulation of seismic waves that propagate from the bedrock through the soil are demonstrated. The models describe both longitudinal and transverse cross-sections of pipelines and the soil-pipe interaction is modelled as a nonlinear behaviour. The effects of uniform ground with different burial depths, soil layer thickness, soil stiffness and bedrock geometry on the seismic response of reinforced concrete pipelines is studied. Two earthquakes, with high and low frequency contents, are employed for the dynamic analysis. The results show that there is a much smaller risk of damage from high-frequency earthquakes, but that there is a significant effect on the response due to possible irregular ground with inclined bedrock.

  • 2.
    Abbaszadeh Shahri, Abbas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. Islamic Azad University.
    An Optimized Artificial Neural Network Structure to Predict Clay Sensitivity in a High Landslide Prone Area Using Piezocone Penetration Test (CPTu) Data: A Case Study in Southwest of Sweden2016In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Application of artificial neural networks (ANN) in various aspects of geotechnical engineering problems such as site characterization due to have difficulty to solve or interrupt through conventional approaches has demonstrated some degree of success. In the current paper a developed and optimized five layer feed-forward back-propagation neural network with 4-4-4-3-1 topology, network error of 0.00201 and R2 = 0.941 under the conjugate gradient descent ANN training algorithm was introduce to predict the clay sensitivity parameter in a specified area in southwest of Sweden. The close relation of this parameter to occurred landslides in Sweden was the main reason why this study is focused on. For this purpose, the information of 70 piezocone penetration test (CPTu) points was used to model the variations of clay sensitivity and the influences of direct or indirect related parameters to CPTu has been taken into account and discussed in detail. Applied operation process to find the optimized ANN model using various training algorithms as well as different activation functions was the main advantage of this paper. The performance and feasibility of proposed optimized model has been examined and evaluated using various statistical and analytical criteria as well as regression analyses and then compared to in situ field tests and laboratory investigation results. The sensitivity analysis of this study showed that the depth and pore pressure are the two most and cone tip resistance is the least effective factor on prediction of clay sensitivity.

  • 3.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Viking, Kenneth
    Trafikverket.
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Wave patterns in the ground: case studies related to vibratory sheet pile driving2017In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
    Abstract [en]

    Vibrations due to pile and sheet pile driving are known to cause discomfort for people, aswell as damage to nearby buildings and structures. To enable prediction of ground vibration levels itis important to acknowledge the wave patterns induced in the ground to correctly determine whichattenuation model to adopt. This paper presents wave patterns in the ground due to vibratory sheetpile driving based on field measurements from three case studies. The results show different wavepatterns in the ground. At the ground surface the wave patterns are elliptical, resembling Rayleighwaves. At depth in the soil the wave patterns are instead strongly polarized in different directions,indicating the presence of P- and S-waves. Moreover, wave patterns tend to become more irregularwith increasing distance from the source. This paper contributes to an improved understanding ofwave patterns in the ground during vibratory sheet pile driving, forming a platform for thedevelopment of a reliable prediction model.

  • 4.
    Hov, Sölve
    et al.
    GeoMind/LabMind.
    Prästings, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Persson, Erik
    Bjerking.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    On empirical correlations for normalised shear strengths from fall cone and direct simple shear tests in soft Swedish clays2019In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
  • 5.
    Lingwanda, Mwajuma
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nyaoro, D.L.
    Correlations of SPT, CPT and DPL data for sandy soil in Tanzania2015In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 33, no 5, p. 1221-1233Article in journal (Refereed)
    Abstract [en]

    In Tanzania, standard penetration test (SPT) is the most commonly used in situ test for foundation design site investigations. In an effort to increase the amount of geotechnical information at low cost, the quicker and much cheaper dynamic probing of light (DPL) hammer is sometimes performed along with SPT to supplement the expensive SPT. Nevertheless, the information gathered with DPL has been applicable only for site stratification. Recently, the static cone penetration test (CPT) has also been introduced in the country with a view to combining these methods in site investigations. In this study, side by side testing was performed with the three in situ methods and correlations established through regression analysis and arithmetic mean methods. Results indicate that DPL data correlate better with CPT than SPT data, with lower magnitudes of transformation uncertainty. The local SPT–CPT correlations compare fairly well to those in the literature. The established correlations extend the function of DPL data to analysis and design.

  • 6.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Hydraulic Conductivity and Coefficient of Consolidation of Two Sulphide Clays in Sweden2012In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 30, no 1, p. 173-186Article in journal (Refereed)
    Abstract [en]

    The variation and anisotropy in hydraulic conductivity and the coefficient of consolidation was investigated for two Swedish sulphide clays. A series of constant rate of strain oedometer tests was performed on samples trimmed in the vertical and horizontal direction. A methodology to evaluate the horizontal coefficients of consolidation c h via the horizontal hydraulic conductivity k h and the vertical compression modulus M v is proposed. Laboratory evaluations of c h are also compared with determinations of c h from in situ piezometer measurements in vertically drained sulphide clay. Furthermore, the validity of the empirical correlation between hydraulic conductivity change index C k and initial void ratio e 0, C k = 0.5e 0 (Tavenas et al. in Can Geotech J 20(4):645-660, 1983b), was investigated for the sulphide clays. The results from the investigation show large ranges in measured hydraulic conductivities and coefficients of consolidation. However, the results indicate that the correlation C k = 0.5e 0 is valid. The anisotropy in hydraulic conductivity and the coefficient of consolidation of the sulphide clays tested seems to be small. For design purposes, multiple tests for assessment of hydraulic conductivity and the coefficient of consolidation should be made, and a partial factor of safety, depending on the requisite level of safety and the spatial variability of the parameters, should be introduced. For design purposes in this type of clay, k h = k v and c h = c v are suggested.

  • 7.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ali Akbar, Saman
    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.
    Draganovic, Almir
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Uncertainties in Grout Penetrability Measurements; Evaluation and Comparison of Filter pump, Penetrability meter and Short slot2017In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
    Abstract [en]

    To measure grout penetrability in fractured hard rock, various measuring instruments have been developed over the years. Penetrability meter and Filter pump have been designed to use in both the lab and the field. Short slot has been applicable mainly in the lab due to its complexity. The fact, that these instruments have been built based on different assumptions, limitations, and test conditions, makes their results occasionally in contradict. Deficiency in design of the instruments as well as the methods of evaluating grout penetrability is additionally a basis for uncertainty in results. This study is an experimental effort to determine and thoroughly perceive the nature of the most governing uncertainties in grout penetrability measurements. The test apparatus, procedure, and method used to evaluate the grout penetrability in both Penetrability meter and Filter pump were thus modified. The aim was to control the corresponding uncertainties and make their limitations and test conditions as similar as possible with the ones in Short slot. The results suggested that to obtain a more realistic evaluation of the grout penetrability, measurement should be accomplished at both the high and the low pressures with sufficient grout volume using Short slot. Moreover, application of both Filter pump and Penetrability meter is no longer recommended due to the revealed uncertainties.

  • 8. Shabanimashcool, M.
    et al.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Group of Engineering Geology and Geophysics.
    Li, C. C.
    Discontinuous Modelling of Stratum Cave-in in a Longwall Coal Mine in the Arctic Area2014In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 32, no 5, p. 1239-1252Article in journal (Refereed)
    Abstract [en]

    This paper presents a discontinuous numerical approach for studying roof cave-in mechanisms and obtaining the required support capacity of longwall shields in a case study site, the Svea Nord coal mine in Svalbard. The block size in the roof strata and the mechanical parameters of the discontinuities for the numerical model were obtained through back-calculations. The back-calculations were conducted with a statistical method of design of experiment. Numerical simulations revealed that voussoir jointed beams are formed before the first cave-in occurs. The maximum deflection of a roof stratum in the study site prior to the first cave-in is about 70 % of the stratum thickness. The maximum span of the roof strata prior to the first cave-in depends upon the in situ horizontal stress state. The roof beams have a large stable span when they are subjected to high horizontal stress; but horizontal stress would increase the possibility of rock crushing in deflected roof beams. The simulations and field measurements show no periodic weighting on the longwall shields in the study site. Stiff and strong roof beams would result in large first and periodic cave-in distances. As a consequence of having large cave-in distances, the longwall shields must have high load capacity, which can be calculated by the presented numerical approach.

  • 9.
    Shahri, Abbas Abbaszadeh
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Islamic Azad Univ.
    Assessment and Prediction of Liquefaction Potential Using Different Artificial Neural Network Models: A Case Study2016In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 34, no 3, p. 807-815Article in journal (Refereed)
    Abstract [en]

    Soil liquefaction as a transformation of granular material from solid to liquid state is a type of ground failure commonly associated with moderate to large earthquakes and refers to the loss of strength in saturated, cohesionless soils due to the build-up of pore water pressures and reduction of the effective stress during dynamic loading. In this paper, assessment and prediction of liquefaction potential of soils subjected to earthquake using two different artificial neural network models based on mechanical and geotechnical related parameters (model A) and earthquake related parameters (model B) have been proposed. In model A the depth, unit weight, SPT-N value, shear wave velocity, soil type and fine contents and in model B the depth, stress reduction factor, cyclic stress ratio, cyclic resistance ratio, pore pressure, total and effective vertical stress were considered as network inputs. Among the numerous tested models, the 6-4-4-2-1 structure correspond to model A and 7-5-4-6-1 for model B due to minimum network root mean square errors were selected as optimized network architecture models in this study. The performance of the network models were controlled approved and evaluated using several statistical criteria, regression analysis as well as detailed comparison with known accepted procedures. The results represented that the model A satisfied almost all the employed criteria and showed better performance than model B. The sensitivity analysis in this study showed that depth, shear wave velocity and SPT-N value for model A and cyclic resistance ratio, cyclic stress ratio and effective vertical stress for model B are the three most effective parameters on liquefaction potential analysis. Moreover, the calculated absolute error for model A represented better performance than model B. The reasonable agreement of network output in comparison with the results from previously accepted methods indicate satisfactory network performance for prediction of liquefaction potential analysis.

  • 10.
    Spross, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Uotinen, Lauri K.T.
    Department of Civil and Environmental Engineering, Aalto University.
    Rafi, Jalaleddin
    BGC engineering Inc.
    Using observational method to manage safety aspects of remedial grouting of concrete dam foundations2016In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 34, no 5, p. 1613-1630Article in journal (Refereed)
    Abstract [en]

    As concrete dams age, the need for remedial grouting to reduce the seepage and uplift pressure in the rock foundations under them increases. Based on a case study of a Swedish dam with very low calculated safety against sliding, this paper discusses the application of the observational method (as defined in Eurocode 7) to manage safety aspects during remedial grouting. The studied case was complex in that grouting works posed the risk of causing increased uplift pressure, which could have induced sliding failure along a shallow, persistent, horizontal rock joint in the foundation. The approach applied in the studied case mainly followed the principles of the observational method, except in some highly significant safety aspects for which alternative procedures are suggested and discussed. Implementing these procedures along with the observational method offers a coherent framework to manage the safety aspects of the remedial grouting of concrete dam foundations that is in line with modern risk-informed dam safety policies.

  • 11.
    Stille, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Gustafson, Gunnar
    Chalmers.
    Hässler, Lars
    Application of new theories and technology for grouting of dams and foundations on rock2012In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 30, no 3, p. 603-624Article in journal (Refereed)
    Abstract [en]

    Permeation grouting is used to improve rock conditions under dams and foundations. During recent decades, there has been a substantial increase of understanding of the mechanism behind grout spread in fractured rock. It is the penetrability of the grout mix and the spread in the joints which will be the governing factors for the quality of the grout curtain. The flow properties and the pressure will give the required time to achieve the quality. The empirical based refusal and completion criteria of today can be replaced by a more engineering based grouting process. An active control method has been developed in order to govern the grout spread during the grouting operation based on the new theory of spreading of grout. The concept is called the "real time grouting control method". The concept and the latest finding of the mechanism of spreading of the grout in the fractures of the rock mass are presented in the paper. The application of the method on two dam projects is also presented.

  • 12.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Applicability of using GIN method, by considering theoretical approach of grouting design2015In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 33, no 6, p. 1431-1448Article in journal (Refereed)
    Abstract [en]

    In the practice of grouting of fractured rock, currently, empirical methods are used. Amongst them, the GIN method is popular mostly in Europe and has been tried in many projects. The concept of this method is to limit the combination of pressure and injected volume to a specific grout intensity number in order to control the energy induced in the rock fractures and to avoid uplift. However, difficulties in employing this method have been reported, which are mainly due to uncertainties in recognizing the distance of grout penetration and the state of the fractures during grouting and at the completion grouting. In this paper, the purpose has been examining the applicability of the GIN method by defining the characteristic curve of the P·V diagram (referred to here as the hyperbola) and suggesting appropriate completion criteria based on the radius of grout spread around the borehole. This will provide the chance to assign a permitted level of fracture deformation (or jacking) to the GIN by considering the formulation of fracture deformation based on grout propagation in a previously developed theoretical approach by Stille et al. (Geotech Geol Eng 30:603–624, 2012) as a part of the Real Time Grouting Control Method. Thus, in attaining the hyperbola, the identified radius of grout spread is achieved and the resulting fracture deformation at this completion point can be beneficial in improving penetrability. However, if the full extent of this deformation extends beyond the grouted zone, part of the fracture may remain un-grouted, and this will affect the sealing efficiency of the grouting program. This may be continued by selecting a smaller GIN and reducing the grouting pressure as the real time pressure–volume plot moves along the hyperbola, which will bring the fracture back to its initial state as grouting approaches the completion point, i.e. when the grout has spread to the desired distance. This hypothesis has been examined against the grouting works performed in three different real projects, for which the grouting parameters can be determined from the available grouting records. It is concluded that the GIN used in practice was much higher than the theoretically estimated values obtained through the proposed analytical solution. Furthermore, in the grouting of fractures close to the surface, the radius of grout spread impacts the GIN significantly, and only a limited grouting pressure is applicable, thus in using split spacing technique in such circumstances, different GINs should be selected for different sets of boreholes to obtain enough propagation at the maximum applicable pressure. The introduced analytical solution introduced in this paper can be a useful procedure for designing the GIN based on the grout spread. Nevertheless, it becomes complicated in dealing with fracture deformation. In a difficult grouting case where the demand for sealing is high, the recommendation is to use the proposed theoretical approach, which provides detailed information during the actual grouting procedure, by estimation of the radius of grout spread and the state of the fracture in real time

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