Elasto-plastic constitutive model for geotechnical materials with strain-softening behaviour

An elasto-plastic model originally developed at Tsinghua University (Tsinghua elasto-plastic model) for soils reflects the observed non-linearity and dilatancy of soils in laboratory tests. The model incorporates a yield criterion, an associated flow rule and a work-hardening law, which can be determined by laboratory tests. This paper presents a modified Tsinghua elasto-plastic constitutive model, which incorporates a function of plastic work as the hardening parameter in the original Tsinghua elasto-plastic model. The modified model has 12 parameters, which are easily determined using conventional triaxial shearing and isotropic compression tests. It can be used to describe strain hardening followed by strain-softening behaviour and to simulate dilatancy during shear application. The modified model was used to determine the relationship between load and settlement for a shallow footing founded on dense Yongding River sand. The results of the numerical analyses were in agreement with the results of hydraulic gradient laboratory tests. The results showed in a preliminary way that the modified model developed in this study was effective for simulating the strain-softening boundary-value problems common in geotechnical engineering.