传统的基坑抗隆起稳定分析上限法的变形机构在用于饱和黏土基坑时,往往不符合基坑的真实变形。根据软土地区基坑开挖引起的地表沉降曲线,构造了饱和黏土基坑抗隆起稳定性上限分析的变形机构和运动许可速度场,变形机构内部的土体作为连续变形体,且在边界处没有明显的破坏面。提出了一种新的基于上限法的基坑抗隆起稳定性分析方法,该方法采用的变形机构更符合实际的基坑变形,而且可以考虑支护结构入土深度对基坑隆起变形的影响。结合算例与工程实例,并与基于Terzaghi机构和Prandtl机构的上限法、多块体上限法进行对比,验证了本方法的合理性与适用性。
The deformation mechanism of the foundation pit is not consistent with the real in-situ deformation in traditional method for stability analysis. The surface settlement curve caused by foundation pit excavation in soft soil area enables the establishment of the admissible velocity field and deformation mechanism for basal stability problems in excavations. The soil inside the deformation mechanism acts as a continuous deformation body without apparent failure surface at the boundary. A new method for the stability analysis of foundation pit is developed based on upper bound method. The deformation mechanism adopted in the method is more suitable for the foundation pit deformation, considering the influence of the depth of supporting structure on the uplift deformation of foundation pit. The upper bound method based on Terzaghi mechanism and Prandtl mechanism is compared with the multi-block upper bound method in engineering examples to verify its rationality and applicability.