基坑开挖卸荷土体的应力应变及抗剪强度分析

Analysis of Stress-strain and Shear Strength of Unloading Soil in Pit Excavation

基于基坑开挖侧向减载的应力路径,选取武汉地区具有代表性的粉质粘土进行了排水条件下真三轴试验和普通三轴固结剪切试验,得出基坑侧向土体在不同应力状态下的应力与应变、轴向应变与水平向应变和轴向应变与体积应变间的变化关系,并探讨了试验土体的强度变化规律,获得了卸荷土体参数。试验结果表明,相同应力条件下,不同应力状态的土体变形特性不同,在实际开挖围护工程中应根据卸荷土体的实际受力状态考虑采用不同的设计方法和围护体系。

According to the lateral unloading stress path in pit excavation, the ordinary and true triaxial consolidation shear tests are completed under the drainage conditions by choosing the representative silty clay in Wuhan City. The deformation and strength characteristics of silty soil in the lateral unloading condition are obtained, which includes the relationships between stress and strain, the axial strain and horizontal strain, the axial strain and volumetric strain. At the same time, the strength change rule of tested soil is discussed and the parameters of unloading soil are gained. The test results show that the characteristics of soil deformation are different in different stress states under the same stress conditions. Therefore, it must take different design methods and support systems for actual excavation projects based on the true force states of unloading soil.