Study On Macroscopic Elastoplastic Mechanical Properties Of Clay Rock Based On Micromechanics Model

For many years,many scholars at home and abroad have studied the macroscopic elastoplastic mechanical properties of clay rocks.At a meso-scale,clay rocks can be considered as a heterogeneous material consisting of rigid inclusions(calcite and quartz),pores,and clay solids.The internal microstructure of clay rock has an important influence on the macroscopic elastoplastic mechanical properties of the material.Based on the macroscopic elastoplastic mechanical properties of clay rocks,the micromechanics model is established,and combined with finite element numerical simulation,the macroscopic elastoplastic mechanical properties of clay rocks containing porous and rigid spherical inclusions are emphatically studied.The influence of the change of the volume fraction of the pore and the inclusion of rigid mineral particles on the macroscopic elastoplastic mechanical properties of clay rocks under uniaxial compression and triaxial compression(confining pressure 5MPa and 10MPa)was analyzed.The main study contents and results of this thesis are as follows:(1)Based on secant micromechanics theory and Mori-Tanaka method,an elastoplastic micromechanics model for clay rocks containing pores and inclusions is established in the thesis.The relationship between macroscopic elastoplastic properties of clay rocks and their micromechanics structures(pores and mineral inclusions)is established by using analytical method.(2)The finite element software ABAQUS is used to develop the user subroutine USDFLD,and the elastoplastic mechanical properties of clay rock were numerically simulated by finite element method.The results are compared with the results of the micromechanics model presented in this thesis,and the reliability and accuracy of the micromechanics model presented in thesis are verified.(3)The clay rocks under uniaxial compression mainly exhibit dilatancy.The clay rocks under triaxial compression show first shrinkage and then dilatancy.The confining pressure has a great influence on the dilatancy of clay rock,while the influence of pores and inclusion is small.Under uniaxial compression and triaxial compression,the pores strength of clay rock decreases linearly with the increase of the volume fraction of the pores,and increases linearly with the increase of the volume fraction of inclusion and confining pressure.The study results in the thesis provide a theoretical basis and reference for analyzing the influence of rigid inclusion and pores volume fraction on the macroscopic elastoplastic mechanical properties of clay rocks under uniaxial and triaxial compression,and for engineering application of clay rocks.