Transition zones of railway tracks are intended to provide a smooth transition of the riding train, minimizing the effect of the discontinuities that exist along the track. When a train rides from an embankment onto a stiff structure, such as a bridge, tunnel or culvert, an abrupt change in the support stiffness occurs possibly inducing differential settlements. This in long term can yield to the degradation of the tracks and foundations in the transition zones. The differential settlement is especially problematic for high speed rail infrastructure as the "bump" at the transition is accentuated at high speeds. A number of techniques have been proposed or implemented to provide gradual stiffness transition at the problem zones, such as methods to ensure gradually changing pad stiffness, application of long sleepers or installation of auxiliary rails in the transition zone. The problems associated with the transition zones require a complex analysis. For efficient modeling of the mechanisms resulting in gradual line deteriorations in the transition zones the understanding of the 3D and dynamic effects associated with the problem seems to be essential. To enhance our understanding regarding the problem a 3D numerical model has been developed and presented for time domain analysis.

This study compares results from three different testing methods: Resonant Column, Torsional Simple Shear, and Bender Element tests to determine shear modulus. The resonant column and torsional shear tests were performed on the same hollow cylinder specimen. The bender element test was performed on a triaxial specimen with the same void ratio and confining stress as well as others. Several effects were studied, among them confining stress, shear strain amplitude and for the bender element, anisotropic confinement. Testing methods and data analysis are discussed in the paper because data interpretation is very important in these tests. Results showed that the shear modulus values were almost identical between the resonant column and torsional shear but varied somewhat with the bender element results. Further research will focus on influence of stress anisotropy preparation methods.

Cutting and embankment slopes are subject to seasonally changing hydraulic boundary conditions. This results in repeated wetting and drying of the soil mass, which in certain combinations of slope geometry, soil type, fabric feared to induce significant swellshrink cycles raising serviceability issues and possibly lead to extensive down-slope displacements. Since the response of infrastructure embankments is particularly relevant in light of the current global climate change, numerical and centrifuge model studies focusing on saturated overconsolidated clay earthworks - mainly representing cutting slopes - have been carried out to investigate the above mentioned effects. Some of these tests suggested that, even a slope failure may be triggered after a number of cycles due to softening of the soil. More recent centrifuge model test results of compacted glacial till embankment with more shallow slopes reviled that the observed behaviour for heavily overconsolidated steep slopes representing cutting like conditions should not be directly adopted when investigating the behaviour of poorly compacted embankments with dominant inter-granular porosity influencing both hydraulic and mechanical response of the structure. The paper thus aims to improve the understanding by undertaking series of numerical modelling and analysis using Plaxis. The input parameters for the implemented advanced hypoplastic constitutive model that could capture the small-strain nonlinearity have been determined based on earlier and more recent advanced element test results. The boundary conditions were set to match those from the centrifuge tests, and finally the model has been refined to reproduce the experienced hydraulic and mechanical behaviour.