粉砂质泥岩蠕变特性与非线性黏弹塑性本构模型OA北大核心CSTPCD

In order to guarantee the long-term stability of silty mudstone in slope and tunneling projects,the DZSZ-150 multi-field coupling rock triaxial pressure testing machine was used to conduct creep tests on silty mudstone specimens of similar materials under different surrounding pressures.Based on the testing results,a nonlinear viscoelastic-plastic constitutive model describing the whole creep process of silty mudstone was established,and the proposed creep model was verified for its rationality and feasibility by taking the results at a confining pressure of 7 Mpa as an example.It show that the steady-state creep rate of the specimen is related to the magnitude of the deviatoric stress,and with increase of the deviatoric stress,the steady-state creep rate and the deviatoric stress conform to an exponential function relationship;the creep rate in the accelerated creep stage is significantly greater than that in the decelerated creep and steady-state creep at low stress levels,and the creep damage occurs in a very short time;a nonlinear viscoelastic-plastic constitutive model is proposed to describe the whole creep process of the silty mudstone,which can describe the creep-deformation law of the whole process of creep-damage of silty mudstone,reflecting the creep characteristics of silty mudstone under different levels of deviatoric stress,and avoiding the problem that the classical model cannot accurately describe the accelerated creep process.