改进邓肯—张模型在基坑减载土体中的应用  

Improved Duncan-Chang Model and Its Application in Foundation Pit Soil of Unloading

作　　者：何怡[1] 苏丽娜[1] 庄心善[2] 

机构地区：[1]洛阳理工学院土木工程系,河南洛阳471023 [2]湖北工业大学土木工程与建筑学院,武汉430068

出　　处：《建筑科学》2010年第9期87-90,103,共5页Building Science

基　　金：湖北省自然科学基金项目(编号:2002AB001);湖北省教育厅项目(编号:2002A00015)

摘　　要：通过三轴试验模拟基坑开挖过程中侧向减载土体的应力路径,针对武汉地区具有代表性的粉质粘土,进行了一系列真三轴和普通三轴排水固结剪切试验。根据试验结果,对邓肯—张模型进行研究,用基坑开挖侧向卸荷过程中的变形模量计算公式代替邓肯—张模型中基于σ3=常数推导出的切线模量公式,并将该模型应用于平面应变情况,针对Duncan-Chang模型不能反映中主应力的影响,对邓肯-张模型进行了改进,确定了模型中的参数,并用理论计算所得应力-应变关系曲线和试验所得应力-应变关系曲线进行对比分析,验证了该模型对于卸荷工程这类特殊应力路径的适应性。On the basis of the representative samples of silty clay in Wuhan,the lateral unloading soil＇s stress path,which is produced by excavating foundation pit engineering,is simulated through triaxial experiment.A series of consolidated—drained true triaxial test and normal triaxial test were accomplished.According to the results of tests,studies are done to decide the parameter of the Duncan-Chang Model.The modulus formula of the Duncan-Chang Model based on theσ3 = const is replaced with the modulus formula for the foundation soil in the lateral unloading stress path tests.The Duncan-Chang hyperbola nonlinear elastic constitutive model is applied to simulate the plane strain test,a method to improve the ability of the Duncan-Chang model is presented to take into account the effects of the intermediate principal stress on the strength and deformation and all the model parameters have been determined.The adaptability of the model to the stress path of unloading engineering is verified by comparing the theoretical stress-strain relationship and the test stress-strain relationship.

关 键 词：基坑开挖 侧向卸荷 改进Duncan-Chang模型 

分 类 号：TU473.2[建筑科学—结构工程]