软土地区基坑坑底抗隆起稳定计算分析

Analysis of Basal Heave Stability for Excavation in Soft Clay

基坑坑底抗隆起稳定性验算在软土地区基坑工程设计中位居核心地位,不仅关系到基坑的稳定及周边环境的安全,还影响基坑工程的造价。对基坑坑底抗隆起计算方法及适用条件进行梳理,结合工程实例,以极限平衡法中的圆弧滑动模式为基础,计算分析了围护墙插入比、最下道支撑的位置、坑内加固及基坑尺寸对坑底抗隆起稳定性的影响。结果表明增加围护墙插入比、减小最下道支撑与坑底的距离、增加坑底土体加固均能有效增加坑底抗隆起稳定性;对于基坑宽度较小的狭窄基坑应考虑空间约束效应,若以传统的圆弧滑动计算模式则过于保守,会造成较大浪费。

The analysis of the basal heave stability for the excavation is the core of deep excavation engineering design in the soft clay,which not only relates to the stability of the excavation and the safety of the surrounding environment,but also affects the construction cost of the excavation project.In this paper,the analytical methods,and applicable conditions of the basal heave stability for the excavation are combed.Combined with the engineering examples,based on the circular slip failure mode in the limit equilibrium method,the influence of the embedment ratio of the supporting structure,the position of the lowest support,the reinforcement in the excavation and the size of the excavation on the basal heave stability of the excavation are analyzed.The results show that increasing the embedment ratio of the supporting structure,reducing the distance between the lowest support and the excavation,and increasing the soil reinforcement at the excavation can effectively increase the basal heave stability of the excavation;For the narrow excavation with small width,the space constraint effect should be considered.If the traditional circular slip mode is too conservative,it will cause a large construction cost waste.