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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。
Through the triaxial test to simulate the stress path of lateral load-bearing soil during the excavation of the foundation pit, a series of true triaxial and ordinary three-axis drainage consolidation shear tests were carried out for the representative silty clay in Wuhan. Based on the experimental results, the Duncan-Chang model is studied, and the formula of the tangent modulus deduced from the Duncan-Chang model based on the σ3 = constant is used to calculate the deformation modulus in the lateral unloading process of excavation. The model is applied to the case of plane strain. According to the fact that the Duncan-Chang model can not reflect the influence of the middle principal stress, the Duncan-Chang model is improved, the parameters in the model are determined, and the stress-strain curve and stress- Strain curves were compared to verify the adaptability of this model to such special stress paths as unloading engineering.