Effects of swelling during saturation in triaxial tests on compressible Chicago glacial clays are assessed from results of triaxial compression tests on block samples cut from excavations, thin-wall Shelby tube samples, and reconstituted specimens. The results are presented in terms of the stress-strain response during saturation, k0 reconsolidation and shearing. Bender element tests were also performed to investigate the effects of swelling on the shear wave velocities during k0 reconsolidation. Results showed that the swelling during saturation lowered the shear wave velocity, thereby inferring a change in the original structure of natural clay. Responses at strains less than 0.01 % were most affected by the saturation-induced swelling. To minimize these changes, it is recommended that the measured residual stress is applied prior to saturating the soil. Based on these results, the saturation stage should be considered as much a part of a triaxial test as consolidation and shearing.

Deep excavation projects in urban areas need to control ground deformation to avoid structural damage from construction activities. Because of the inherent uncertainties of subsurface conditions, it is not easy to predict the ground deformation during the design phase. The inverse analysis technique can be a practical solution, which involves updating the soil parameters to find the best fit to the field observations. This paper describes the inverse analyses and the results for supported bottom-up excavation site located in Incheon, Korea. Observations of the lateral deformation of the excavation support wall were used for the inverse analyses to find the optimized stiffness. To understand how the optimized parameter evolves throughout the excavation process, the Mohr-Coulomb (MC), hardening soil (HS), and hardening soil with small strains (HSS) models were employed in the investigation, and the responses of each model were compared. This paper summarizes the stiffness evolution of each soil model as the excavation proceeded. Ground settlement results with the optimized stiffness were also discussed.

Geosynthetic-reinforced piled embankments (GRPEs) are very complex structures with three differently behaving inclusions; i.e., piles, geosynthetics and soils. Very careful experiments are needed to investigate the behaviors of these GRPEs. In this study, the results of full-scale experiments conducted on GRPEs with three different geosynthetic reinforcements (GRs) and on an unreinforced piled embankment (PE) are presented. In the experiments, the vertical load transported towards the model piles and the vertical displacements of the soft foam layer underneath the reinforced embankment were measured and compared with the calculation results obtained by the concentric arches model used in the Netherlands. The vertical loads measured in the unreinforced PE and one GRPE agree well with the theoretical values. However, those measured in the two other GRPEs were significantly lower than the theoretically predicted values. It was concluded that these discrepancies were caused by two weak points in the execution of the experiments: inappropriate GR fixating at the sides of the model in combination with significant unexpected compaction in the soft foam layer that originated from the compaction procedure. These factors should be considered carefully in future experimental research to attain a better understanding of the behaviors of GRPEs.

Aims/hypothesis: One of the critical mechanisms determining creep in granular materials is the breakage of soil particles. This study aims at evaluating the time-dependent creep deformation of calcareous sand at low effective stress conditions. Methods: K₀ creep tests were performed for both calcareous and silica sands at low stresses of 65 and 120 kPa, and the results of creep tests were compared with the results of constant rate of strain (CRS) tests at high stress levels up to 12 MPa. For a quantitative evaluation of the effect of the particle breakage on the creep deformation of calcareous sand, the relative breakage ( $$B_{r}$$B r ) was determined based on the results of sieve analyses. Results: The results demonstrate that Tunisia calcareous sand experiences significant particle breakage during creep and the consequent creep deformation at low stress level. The determined $$B_{r}$$B r after creep at low stress level is comparable with that after the CRS test at high stress level. Conclusions: High potential of particle breakage inherited by characteristic minerology of the calcareous Tunisia sand significantly influences the creep deformation at low stress level.