Secondary Development And Application Of Soft Clay Boundary Surface Model In ABAQUS

Due to the structure and anisotropy of soft clay,the mechanical properties of natural soft clay are different from those of laboratory remolded soil.the study of structure and anisotropy has been an important research direction of soil mechanics.With the development of computer technology,the functions of software related to geotechnical engineering,such as ABAQUS,have been improved rapidly.As an international geotechnical engineering software,ABAQUS contains many geotechnical material models and provides user subprograms for secondary development.Then the modified Cam-clay model in ABAQUS does not take into account the structure and anisotropy of materials,it can't reflect the mechanical properties of materials.The main work and research contents of this paper are as follows:1.Based on the basic theory of modified Cam-clay model considering structure and anisotropy,the elastoplastic constitutive relation and stress-strain matrix are derived.The boundary interface model considering structure and anisotropy is developed by Fortran language and explicit integral algorithm,then the user material subroutine UMAT is used to simulate in ABAQUS.2.The secondary development subprogram developed in ABAQUS is used to simulate the triaxial undrained test of the model,and the effects of different anisotropic parameters,such as???,and different structural parameters ₀r?k_d?,on the simulation results are analyzed.The results show that for the triaxial undrained shear test,the value of anisotropy parameters???,has no significant effect on the simulation results,The different values of structural parameters ₀r?k_d?B will have a great influence on the stress-strain relationship and stress path of the model,and will make the soil show the characteristic of strain softening,which proves that the UMAT subroutine has good stability and accuracy.3.The anisotropy and structure of triaxial undrained shear are compared with the simulation results of modified Cam-clay model.The results show that the effect of structure on shear strength of soil is more significant than that of anisotropy.The shear strength of soil with structure is higher.The UMAT subroutine is applied to the engineering simulation of the embankment foundation,and the pore water pressure at the bottom of the foundation and the settlement of the foundation are analyzed.It is proved that the UMAT subroutine can better simulate the consolidation settlement problems such as loading and preloading of the foundation.