Continuous compaction control (CCC) offers a promising alternative to conventional spot tests for earthwork quality assurance. However, establishing reliable correlations between intelligent compaction measurement values (ICMVs) and traditional stiffness metrics, such as the deformation modulus (E_v2) from static plate load tests (PLT), remains a challenge. This study investigated the influence of PLT plate size and vibratory roller type on these correlations through a series of full-scale compaction tests conducted on a granular soil bed. Two plate diameters (300 and 600 mm) and two rollers with different static linear loads (36 and 65 kg/cm) were employed. Sixteen ICMVs spanning acceleration-, mechanics-, and energy-based categories were computed and correlated with E_v2. The results showed that the 600-mm plate, despite producing lower E_v2 values, consistently yielded stronger correlations with the representative ICMVs. The lighter roller produced stronger correlations than the heavier roller, likely due to reduced contact loss and better alignment of measurement depths. Mechanics-based ICMVs performed best, with the vibration modulus (E_vib) during the loading phase showing the strongest correlation (R up to 0.8). These findings confirm that E_vib is a suitable indicator for compaction quality control, suggest that the larger plate is preferable for calibration purposes, and underscore the need for machine-specific calibration.

Jordpackning är en av de mest grundläggande och kritiska jordförstärkningsmetoderna, som utförs i nästan alla typer av byggprojekt, med särskild betydelse inom infrastruktursektorn. En väl utförd packning är avgörande för en konstruktions funktion och livslängd, och med tanke på dess betydande miljöpåverkan är det av yttersta vikt att optimera packningsarbetet. För känsliga konstruktioner som järnvägar, där minimala sättningar är ett krav, är optimal packning av yttersta vikt. Detta gäller i synnerhet vid byggnation av moderna järnvägssystem med ”slab-track”, där undergrundens stabilitet är avgörande för att minimera sättningar. Idag finns ett stort behov av att effektivt kunna verifiera packningsresultat. Nuvarande metoder, såsom plattbelastningsförsök (PLT), är tidsödande och ger endast diskreta mätpunkter, vilket begränsar den yttäckande kontrollen. Därför är det av stor vikt att etablera tillförlitliga korrelationer mellan intelligenta packningsmått (ICMV) – som möjliggör yttäckande packningskontroll (YPK) – och konventionella punktprov.

Denna studie adresserar detta behov genom att presentera fullskaliga, kontrollerade laboratorieförsök. Syftet var att systematiskt utvärdera hur plattstorlek (300 och 600 mm) och vält-typ (Dynapac CA3500D och CA6500D med statiska linjelaster på 36 och 65 kg/cm) påverkar deformationsmoduler från PLT samt 16 olika ICMV, vilka spänner över kinematiska, mekanikbaserade och energibaserade kategorier.

Resultaten visar att 600 mm-plattan, trots något lägre deformationsmodul E_v2, gav konsekvent förbättrade korrelationer med ICMV, sannolikt tack vare dess djupare influensvolym. Den tyngre välten producerade högre E_v2 och lägre variabilitet än den lättare. Analys av ICMV-samband avslöjade stark redundans och tre tydliga kluster (harmonisk-, styvhets- och energibaserade), vilket stöder användningen av en enskild representant från varje kluster vid kalibrering. Vibrationsmodulen E_vib och harmonisk-baserade index presterade bäst i korrelation med PLT, medan energibaserade index var mindre lämpliga.

Sammanfattningsvis förbättrar större PLT-plattor och mekanikbaserade ICMV korrelationen mellan YPK och PLT, men vältspecifik kalibrering är fortsatt nödvändig. Dessa resultat ger praktisk vägledning för mer tillförlitliga YPK-baserade arbetsflöden för kvalitetssäkring.

Soil compaction is one of the most fundamental and critical ground improvement methods, performed in almost all types of construction projects, with particular significance within the infrastructure sector. Well-executed compaction is crucial for the performance and service life of a structure, and given its significant environmental impact, optimizing compaction work is of the utmost importance. For sensitive structures such as railways, where minimal settlement is a requirement, optimal compaction is vital. This applies in particular to the construction of modern railway systems using “slab-track”, where subgrade stability is decisive for minimizing settlement. Today, there is a great need to effectively verify compaction results. Current methods, such as the plate load test (PLT), are time-consuming and provide only discrete measurement points, limiting area-wide control. Therefore, it is highly important to establish reliable correlations between intelligent compaction measurement values (ICMV) – which enable continuous compaction control (CCC) – and conventional spot tests.

This study addresses this need by presenting full-scale, controlled laboratory experiments. The aim was to systematically evaluate how plate size (300 and 600 mm) and roller type (Dynapac CA3500D and CA6500D with static linear loads of 36 and 65 kg/cm) affect deformation moduli from PLT as well as 16 different ICMVs, spanning kinematic, mechanics-based, and energy-based categories.

The results show that the 600 mm plate, despite a slightly lower deformation modulus E_v2, yielded consistently improved correlations with ICMVs, likely due to its deeper influence volume. The heavier roller produced higher E_v2 values and lower variability than the lighter roller. Analysis of relationships among ICMVs revealed strong redundancy and three distinct clusters (harmonic-, stiffness-, and energy-based), supporting the use of a single representative from each cluster during calibration. The vibration modulus E_vib and harmonic-based indices performed best in correlation with PLT, while energy-based indices were less suitable.

In conclusion, larger PLT plates and mechanics-based ICMVs improve the correlation between CCC and PLT, but roller-specific calibration remains necessary. These results provide practical guidance for more reliable CCC-based workflows for quality assurance.

The transition zones between bridges and adjacent tracks in high-speed railway systems arecritical areas where dynamic interactions between the train and track infrastructure can lead to significantmaintenance and structural challenges. These zones are particularly susceptible to issues due to the abruptchange in stiffness between the bridge structure and the adjacent track, resulting in complex stress patterns anddifferential settlement. This study investigates the impact of train travel direction on the dynamic behavior andstress distribution within bridge-transition zones. Advanced numerical modeling techniques, including finitedifference method (FDM) for modeling the rail structure, and the discrete element method (DEM) forsimulating the behavior of sleepers, ballast, and sub-ballast layers, were utilized to provide a comprehensivesimulation of the effects of trains approaching or departing from bridges. The findings reveal that train traveldirection affects structural behavior, track deformation, and differential settlement within these zones. Dynamic loading conditions, which vary depending on whether the train is moving onto or off the bridge, leadto uneven stress distributions. These stress variations contribute to differential settlement, where the track andunderlying materials settle at different rates, exacerbating track wear and increasing maintenance needs. Thisstudy provides key insights into enhancing the design and upkeep of bridge-transition zones by analyzing theimpact of train travel direction. The findings enable engineers and designers to develop strategies to mitigatethe adverse effects of differential settlement and stress concentration, thereby enhancing track longevity,reducing maintenance costs, and improving the overall safety and reliability of high-speed railway systems.

Strength verification of dry deep mixed columns is almost exclusively performed by column penetration tests (KPS) using a probe with two wings shearing into the column. Guidelines specify a constant bearing capacity factor (NKPS ) of 10 to determine the shear strength of the column. This factor has, however, undergone little research, and there are considerable research gaps. Results from laboratory scale tests are presented herein, where cement-improved kaolin columns with three different strengths were tested with KPS and cone penetration tests (CPT). The results showed NKPS ranging from 7.3 to 7.8 at low degrees of confinement around the columns, up to 15.4–16.5 at high degrees of confinement. The column strength did not significantly affect NKPS . The results further indicates that extraction to penetration ratio can be used to predict NKPS . Equivalent bearing capacity factors for CPT were 5.4–7.8 for tests only performed in low degrees of confinement. The findings present new knowledge that degree of confinement is crucial for NKPS, which has important practical implications, particularly that current guidelines oversimplify and might yield unconservative column strengths with increased risk of failure.

Jordpackning är den absolut vanligaste jordförstärkningsmetoden som används i princip i alla byggprojekt, och där är packningskvaliteten avgörande för hållbar infrastruktur. Traditionella metoder för kvali­tetskontroll, såsom plattbelastningsförsök (PLT), brister dock i effektivitet och täckning. Yttäckande packningskontroll ger en kontinuerlig och yttäckande uppföljning, men dess korrelation med plattbelast­ningsförsök har varit svag. Utvecklingen av yttäckande packnings­kontroll har under lång tid varit begränsad, men med nya tekniska möjligheter har intresse återigen väckts för att utveckla tekniken. Som en fortsättning på en serie tidigare utförd forskning, syftar detta doktorandprojekt till att vidareutveckla yttäckande packningskontroll med användning av moderna mät- och analysverktyg. I ett första steg korreleras PLT mot gamla och nya värden från yttäckande pack­ningskontroll. Det slutgiltiga målet är dock att utveckla den yttäckande packningskontrollen så att behovet av statiska plattbelastningsförsök försvinner.

The partial factor method is the most common approach to verify structural safety in Eurocode 7. Given the ongoing discussion on the European level to include also underground excavations in rock in the scope of the Eurocodes, there is a clear need to investigate the applicability of partial factors to the design of rock tunnels. However, implementing fixed partial factors, in accordance with the suggestion in the current Eurocode 7, may not be appropriate to account for the large uncertainties and variable conditions prevalent in rock engineering. This paper studies the critical characteristics and underlying assumptions of different reliability-based partial factor formats. The suitability of the analyzed partial factor formats to evaluate safety is analysed and discussed with reference to a design example of a rock-shotcrete interaction system for support against block failure in an underground opening. The results show that reliability-based partial factor methods outperform the traditional partial safety format suggested in the Eurocode in terms of accuracy and consistency.

There is an increasing interest in creating high-resolution 3D subsurface geo-models using multisource retrieved data, i.e., borehole, geophysical techniques, geological maps, and rock properties, for emergency managements. However, dedicating meaningful, and thus interpretable 3D subsurface views from such integrated heterogeneous data requires developing a new methodology for convenient post-modeling analyses. To this end, in the current paper a hybrid ensemble-based automated deep learning approach for 3D modeling of subsurface geological bedrock using multisource data is proposed. The uncertainty then was quantified using a novel ensemble randomly automated deactivating process implanted on the jointed weight database. The applicability of the automated process in capturing the optimum topology is then validated by creating 3D subsurface geo-model using laser-scanned bedrock-level data from Sweden. In comparison with intelligent quantile regression and traditional geostatistical interpolation algorithms, the proposed hybrid approach showed higher accuracy for visualizing and post-analyzing the 3D subsurface model. Due to the use of integrated multi-source data, the approach presented here and the subsequently created 3D model can be a representative reconcile for geoengineering applications.

Permanent deformation in ballast layers is a major contributing factor to the railway track geometry deterioration. In spite of a considerable amount of research on understanding and predicting performance of ballast layers, accurately capturing their settlements remains a challenge. In order to contribute to solving this important issue, a new numerical method for predicting ballast settlements is presented in this paper. This method is based on the finite element (FE) method combined with a constitutive model that captures permanent deformation accumulation in unbound materials under cyclic loading. This allows predicting permanent deformations of large structures and at large number of load cycles in a computationally efficient manner. The developed constitutive model is validated based on triaxial test measurements over wide range of loading conditions. Stress state in ballast layers has been examined with a 3D FE model, for several embankment structures and traffic load magnitudes. The determined stress distributions and loading frequencies were used as an input of the constitutive model to evaluate permanent strains and settlements of ballast layer. The influence of embankment structural designs and traffic loading magnitudes on the ballast layers settlements is examined and the results obtained are compared with the existing empirical performance models.

Modelling railway projects has a main challenge in the discrete element method (DEM). The granular material of the embankment consists of millions of fine angular particles which are difficult to model due to the long computational time. The long computational time also prevents the modeling of the higher number of loading cycles. As a result, researchers prefer to simulate the project in 2D to accelerate the simulation. While 2D simulations present a seemingly simple option for modeling railways, they tend to oversimplify the intricacies of particle interactions and the distribution of stress. Nonetheless, the extent to which these simplifications affect the authenticity of the simulations has remained ambiguous. In this study, the periodic cell replication method is used to build extensive long railway tracks significantly faster than conventional methods. Then, this DEM model is calibrated against the measurement results of a physical full-scale ballasted track. The model is then used to simulate several railway projects with different initial particle arrangements and model dimensions in both 2D and 3D. The results show that the 2D models are more dependant on the initial particle arrangement which shows different behavior for the same model. In addition, 2D simulations are incapable of reproducing the principal stress rotation in granular layers due to the moving load of the train wheel. As a result, 3D DEM simulations using the periodic cell replication method is suggested for studying the railway tracks.