淤泥地层中深基坑降水影响范围及地层变形稳定性分析

Research on Dewatering and Deformation Stability of Deep Foundation Pit in Silt Stratum

基坑降水影响范围及地层变形稳定性是淤泥地层中深基坑工程设计和施工的关键问题之一。本文通过对某淤泥地层中深基坑降水特征分析得出,止水帷幕能有效阻止连续墙外侧水向基坑横向渗流,减少降水对外部环境影响;基坑降水引起的地表沉降影响范围和基坑外侧地下水位变化影响范围均与降水深度关系不大,集中影响范围分别约为80 m、40 m;淤泥地层中基坑降水后水位下降相对砂质黏性土或粉质黏土较小,但地表沉降量却是三者中最大的。因此,在淤泥质土地层中深基坑的设计和施工,应特别注意由降水造成的基坑周围地表建筑物的倾斜和沉降。

The dewatering on a deep foundation pit in a silt stratum is one of the key issues of it＇ s design and construction. Based on a numerical analysis of deep foundation pit in the silt stratum, the research results are pres- ented as follows ： Firstly, the water inflow in the deep foundation pit can be efftively stopped by a waterproof wall, which aslo can reduce the impact of dewatering on the external environment ; Secondly, the scope of surface subsid- ence and change of groundwater level caused by dewatering has little influence on dewatering depth, the influence scope is 80 m and 40 m respectively; Thirdly, under the same condition of dewatering the groundwater level dropped in the silt stratum is smaller than sandy clay or silty clay, but the amount of surface subsidence is the lar- gest.