Investigation of a hypoplastic model with two different inter-granular strain extensions for undrained behaviour of silty sand

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4. Investigation of a hypoplastic model with two different inter-granular strain extensions for undrained behaviour of silty sand

This paper describes the results of a back analysis of element tests with monotonic and cyclic loading on a silty sand applying a hypoplastic constitutive model together with two different intergranular strain extensions. The material used in the experiments is an Ethiopian sand with 35.5% non-plastic fines content. After calibration of the material parameters, element test simulations were performed. In a first step, the performance of the constitutive model was studied by comparing the calculated and measured stress-strain relationships and effective stress paths from undrained monotonic triaxial tests with different initial pressures. In a second step, a comparison of numerical and experimental data was undertaken for undrained cyclic triaxial tests performed with different cyclic stress ratios CSR [0.25 to 0.75] and relative densities D_r [20% to 50%]. In the latter case, the comparison focussed on the build-up of excess pore water pressure and the accumulation of axial strain with increasing number of cycles. The results showed the capability of the hypoplastic constitutive model and its extensions to simulate the cyclic behaviour and the liquefaction potential of the silty sand, but also revealed limitations in some cases.

10th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2023)

1. Constitutive modelling for saturated and unsaturated soils