Constitutive model for Chengdu clay with some graves and its implementation in FLAC^3D

The results of the triaxial shear tests on Chengdu clay with some gravels show that: (i) The samples behave as strain-hardening type while the deviator stress increases rapidly and reaches steady state in the small axial strain level. (ii) The volumetric strain increases slowly and does not achieve stability when the axial strain increases at the same speed. So the samples behave slightly dilatancy with the increasing speed of the volumetric strain within small axial strain. They behave apparent contraction with the increasing volumetric strain when plastic flow occurs. As the capability of the modified Cam-clay model is insufficient to describe such features well, Wei Rulong model considering the cohesion c is incorporated into FLAC^3D to stimulate the hardening properties of soils, which considers the influence of the plastic volumetric strain hardening and the volumetric strain caused by the shearing strain based on the performance of modified Cam-clay model embedded in the FLAC^3D. The simulated results show that the proposed model can reflect the results of the triaxial shear tests well. By comparing the test data with the calculated results, it is indicated that the strength of the samples increases, and its water retentivity becomes weaker with the increase of the contents of gravels.