复杂应力路径下饱和砂土静态液化失稳预测  

Prediction initiation of static liquefaction of saturated sand under complex stress paths

作　　者：黄茂松[1,2] 童森杰 时振昊 吕玺琳[1,2] HUANG Mao-song;TONG Sen-jie;SHI Zhen-hao;LÜ Xi-lin(Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学岩土及地下工程教育部重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土工程学报》2021年第1期19-26,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(11972260,41672270)。

摘　　要：饱和砂土应力–应变关系具有各向异性和状态相关特性,因此其静态液化的触发与应力路径密切相关。现有文献已提出多种静态液化判别准则,但其准确性往往仅在三轴应力路径下被进行校验。对于涉及主应力方向旋转和不同中主应力比的复杂应力路径,现有判别准则是否可以准确预测静态液化的触发有待进一步验证。为此,基于状态相关各向异性砂土本构模型,结合前人的空心圆柱扭剪单元体试验,比较了二阶功、弹塑性刚度矩阵对称部分和失稳模量3种准则对复杂应力路径下砂土静态液化失稳预测的效果。发现包括:基于弹塑性刚度矩阵对称部分的失稳触发表达式不依赖于加载路径,具有更好的通用性,其预测的失稳点早于或与实际失稳点吻合;失稳模量理论可预测实际液化失稳的位置,但判定表达式因加载条件不同而变化。获得了复杂应力路径下的失稳线,分析了静态液化触发前砂土可发挥峰值摩擦角受中主应力、主应力方向等因素的影响。The stress-strain relations of saturated sand are anisotropic and state-dependent,thus the initiation of its static liquefaction relies on stress paths.While various criteria have been proposed to predict the triggering of static liquefaction,their accuracy is normally examined under triaxial stress paths.When subjected to complex stress paths that involve the rotation of the principal stress directions and different relative magnitudes of the intermediate principal stress,the accuracy of these criteria remains to be an open question.Here the capacity of three criteria is evaluated,including the second-order work,symmetric part of the elastoplastic stiffness matrix and instability modulus,for predicting the static liquefaction under complex stress paths,by employing a state-dependent,anisotropic constitutive model and comparing against the hollow cylindrical torsional shear tests on Toyoura sand.It is found that:(1)The instability condition derived from the elastoplastic stiffness matrix does not depend on the stress paths,thus being more general,and the predicted liquefaction initiation is earlier than or coincident with the actual instability point.(2)The instability modulus approach can predict the initiation of static liquefaction,however,the instability conditions vary across different loading paths.The instability line is obtained,through which the influences of factors like the intermediate principal stress and the principal stress directions on the peak mobilized friction angle before liquefaction are studied.

关 键 词：砂土 静态液化 各向异性 中主应力比 液化判别 失稳线 

分 类 号：TU43[建筑科学—岩土工程]