正常固结饱和黏性土的三剪次加载面模型  

Triple-shear subloading surface model for saturated clays in normal consolidation

作　　者：蔡晓锋 李春博 路祥 胡小荣 CAI Xiaofeng;LI Chunbo;LU Xiang;HU Xiaorong(School of Infrastructure Engineering,Nanchang University,Nanchang 330031,China)

机构地区：[1]南昌大学工程建设学院,江西南昌330031

出　　处：《南昌大学学报（工科版）》2022年第2期146-154,共9页Journal of Nanchang University(Engineering & Technology)

基　　金：国家自然科学基金资助项目(11362016,10862004)。

摘　　要：以三剪统一强度准则为破坏准则,采用坐标平移法推导出能够反映中间主应力效应、土体拉压差效应和区间效应的三剪破坏应力比,来替换修正剑桥模型的原本破坏应力比从而得到三剪统一屈服函数。基于该屈服函数,并结合次加载面理论,提出适用于循环荷载条件下的正常固结饱和黏性土的三剪次加载面本构模型。对模型参数u,C和χ做了敏感性分析,发现参数u,C和χ大小都会影响对循环荷载条件下饱和黏性土的棘轮效应和曼辛效应;为验证所提模型的正确性,将该模型的计算结果、文献中两种饱和黏土动三轴试验结果以及饱和Kaolin黏土的双面模型预测结果做了比较,结果表明所提模型能够较好地反映正常固结饱和黏土的应力应变关系,随着循环次数的不断增加,所建模型的模拟结果能不断产生累计塑性应变和累积孔隙水压力,且能够形成滞回圈。通过真三轴数值模拟分析可知,饱和黏性土的塑性偏应变在加载前期发展较快,之后相对减小;单一变量下,分别增大最小主应力和中间主应力,均会增大土体的抗剪强度。Taking the triple-shear unified strength criterion as the failure criterion,the coordinate translation method was used to derive the triple-shear failure stress ratio,which can reflect the intermediate principal stress effect,soil tension pressure difference effect and interval effect.The triple-shear unified elastic-plastic constitutive model was obtained by replacing the original failure stress ratio of the modified Cambridge model.Based on the model and the secondary loading surface theory,a constitutive model of saturated clay under cyclic loading was proposed.Through the parameter sensitivity analysis of the secondary loading surface theory,it was found that the parameters u,C andχin the model would affect the ratcheting effect and manning effect of saturated clay under cyclic loading.In order to verify the correctness of the proposed model,the numerical simulation results of the model were compared with the dynamic triaxial consolidated undrained test results of normally consolidated saturated clay in the literature.The proposed model can well reflect the stress-strain relationship of normally consolidated saturated clay.Through the true triaxial numerical simulation analysis,it can be seen that the plastic deviator strain of saturated clay developed rapidly in the early stage of loading,and then decreased relatively;under a single variable,the shear strength of soil increased with increasing the minimum principal stress and the intermediate principal stress.

关 键 词：正常固结饱和黏性土 三剪次加载面模型 三剪统一强度准则 坐标平移法 循环荷载 

分 类 号：TU432[建筑科学—岩土工程]