基于三轴不排水有效应力路径的结构性剑桥模型的修正研究  

Modification of structured Cam-clay model based on triaxial undrained effective stress path

作　　者：加瑞[1,2] 李逸群 雷华阳 姜宇轩[1,2] JIA Rui;LI Yiqun;LEI Huayang;JIANG Yuxuan(School of Civil Engineering,Tianjin University,Tianjin 300350,China;Key Laboratory of Coast Civil Structure Safety of Ministry of Education,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学建筑工程学院,天津300350 [2]天津大学滨海土木工程结构与安全教育部重点实验室,天津300350

出　　处：《岩土工程学报》2025年第1期115-124,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52378362);天津市科技计划项目(21JCYBJC00380)。

摘　　要：室内外试验和工程实践都表明天然沉积黏土具有一定的结构性,因此建立结构性本构模型对准确预测天然黏土的力学响应和解决实际岩土工程问题具有重要意义。首先,基于结构性黏土的三轴固结不排水试验的有效应力路径对结构性剑桥(SCC)模型进行了两点改进:(1)对附加孔隙比Δe的计算公式进行了修正,可以准确模拟结构性黏土超过临界状态线后的有效应力路径;(2)考虑了屈服面内的塑性即亚屈服特性,可以较好地模拟屈服面内的有效应力路径然后,利用修正结构性剑桥(MSCC)模型对结构性黏土的侧限压缩试验、三轴固结不排水和三轴固结排水试验进行了模拟计算,并与试验结果和SCC模型的计算结果进行了对比分析,结果表明MSCC模型可以更好地模拟结构性黏土的三轴不排水有效应力路径以及侧限压缩和三轴固结排水试验的应力应变曲线。最后,对MSCC模型中的参数β(屈服面内塑性变形参数)、p'_(yi)(初始结构屈服应力)、Δe_(i)(初始附加孔隙比)、b(结构破损速率)、γ(剪切引起结构破损的参数)和ω(反映结构性对塑性流动准则的影响)进行了参数敏感性分析,结果表明参数β影响结构性黏土屈服面内的有效应力路径,参数p'_(yi)影响峰值强度,参数Δe_(i)影响残余强度,参数b和γ影响峰值后的强度衰减速率,参数ω影响强度开始衰减时的偏应变大小。Both laboratory and in-situ tests and engineering practices show that naturally sedimented clays have a specific structure.Therefore,establishing a structural constitutive model is of great significance in accurate predicting the mechanical responses of natural clays and solving practical geotechnical engineering problems.Firstly,based on the effective stress path of the consolidated undrained triaxial tests on structured clay,two improvements are made to the structured Cam-clay(SCC)model:(1)The formula for calculating the additional void ratioΔe is modified,which can accurately simulate the effective stress path of the structured clay beyond the critical state line.(2)Considering the plasticity in the yield surface,i.e.,subyielding characteristic,the effective stress path in the yield surface can be well simulated.Then,the modified structured Cam-clay(MSCC)model is used to simulate the confined compression tests,the consolidated undrained and drained triaxial tests on the structured clay.The calculated results are compared with the experimental ones and those by the SCC model.The results show that the MSCC model can better simulate the triaxial undrained effective stress path and stress-strain curves of the confined compression and consolidated drained triaxial tests on the structured clay.Finally,the sensitivity analyses of parametersβ(plastic deformation parameter in yield surface),p'_(yi)(initial structural yield stress),Δe_(i)(initial additional void ratio),b(structure degradation rate),γ(shear-induced structure degradation parameter)andω(reflecting the influences of soil structure on plastic flow criterion)in the MSCC model are carried out.The results show that parameterβaffects the effective stress path in the yield surface of structured clay,parameter p'_(yi)affects peak strength,parameterΔe_(i) affects the residual strength,parameters b andgaffect the strength degradation rate after the peak value,and parameterωaffects the magnitude of deviatoric strain when the strength begins to degrade.

关 键 词：结构性黏土 结构性剑桥模型 有效应力路径 亚屈服 附加孔隙比 

分 类 号：TU43[建筑科学—岩土工程]