南昌地铁含泥饱和砂土的三剪次加载面模型  

Triple-shear subloading surface models for saturated clayey sand in the Nanchang metro

作　　者：胡小荣 路祥 袁豪 HU Xiaorong;LU Xiang;YUAN Hao(School of Infrustructure Engineering,Nanchang University,Nanchang 330031,China)

机构地区：[1]南昌大学工程建设学院,南昌330031

出　　处：《振动与冲击》2024年第10期9-20,共12页Journal of Vibration and Shock

基　　金：国家自然科学基金(10862004,11362016)。

摘　　要：以三剪强度准则作为破坏准则,推导出饱和土的三剪破坏应力比。考虑到砂土的剪胀特性,引入剪胀状态参量对三剪破坏应力比进行修正得到相变应力比。用相变应力比对修正剑桥模型中为定值的破坏应力比进行替换,得到新的屈服函数。将其与次加载面理论相结合,提出含泥饱和砂土三剪次加载面模型。取用南昌地铁某路线路段地下砂土和黏土作为试验土样,砂土中掺入粒径小于0.075 mm的黏土作为含泥砂土,并设定密实度为70%的试样含泥量为0、5%和10%,通过相关土工试验确定模型参数。将本构模型计算结果与常规静三轴试验结果和循环常规动三轴试验结果进行对比验证。静三轴试验验证结果表明,本构模型计算结果与试验结果变化规律基本一致,验证了该本构模型的正确性。其他条件相同情况下,随着含泥量增大,土体抗剪强度增大,体积剪缩阶段变长,剪胀现象越不明显。动三轴试验验证结果表明,本构模型数值计算曲线与试验结果吻合较好,在加载初期土体塑性应变发展较快,随着加载和卸载的不断交替以及循环次数的不断增加,滞洄圈变得越来越密集。Taking the triple-shear strength criterion as the failure criterion,the triple-shear failure stress ratio of saturated soil was derived.Considering the dilatancy of sand,the phase transformation stress ratio was modified by introducing dilatancy state parameters.A new yield function was obtained by replacing the fixed failure stress ratio in the modified Cambridge model with the phase transformation stress ratio.Combining the new yield function with the theory of subloading surface model,a triple-shear subloading surface model for saturated clayey sand was proposed.The underground sand and clay in a section of Nanchang Metro were taken as test soil samples.Clay with particle size of less than 0.075 mm was added to the sand to make the clayey sand.The compactness of the sample was set to 70%,and the clay content was set to be 0,5%and 10%,and the model parameters were determined by relevant geotechnical tests.The results of the proposed constitutive model were compared with those of the conventional static triaxial tests and cyclic dynamic triaxial tests.The results of static triaxial tests show that the calculation results of the constitutive model are basically consistent with the experimental results,which indicates the validity of the constitutive model.Under the same other conditions,with the increase of clay content,the shear strength of soil increases,the shear shrinkage stage becomes longer,and the dilatancy phenomenon becomes less obvious.The results of dynamic triaxial tests show that the numerical calculation curves by the constitutive model are in good agreement with the experimental results.In the initial stage of loading,the plastic strain of soil develops rapidly.With the continuous alternation of loading and unloading and the increasing number of cycles,the hysteresis loops become more and more dense.

关 键 词：含泥饱和砂土 三剪次加载面 三剪强度准则 本构模型 三轴试验 

分 类 号：TU432[建筑科学—岩土工程]