泵站深基坑支护结构的离心模型试验研究

Centrifugal model test of supporting structure of pump station deep foundation pit

由于2016年武汉市政排水出现问题,原定于2019年完工的江南泵站要求提前满足排水条件。为了满足工期要求必须对原定地下连续墙+3道内支撑的支护结构进行优化。为了明确优化后支护方案的可行性,进行了原定支护方案和优化支护方案的离心模型试验,分析了反映基坑稳定的关键变形量,即桩水平位移与弯矩、基坑周边土体沉降,结果发现支护结构变更为大直径钻孔灌注桩+1道内支撑后围护结构水平位移、弯矩以及基坑外地表沉降均有一定程度的增加但仍能确保基坑稳定。研究结果表明:减少内支撑数量及围护结构刚度会导致支护结构水平位移和地表沉降的最大值有一定程度的增长,水平位移最大值出现位置下移,但是对基坑外地表沉降规律影响较小。研究过程对类似的基坑工程具有借鉴意义。

Drainage problems occurred in Wuhan city in 2016,and the Jiangnan Pump Station was required to be put into use in advance.In order to meet the requirements of the construction period,the original supporting structure of continuous underground-wall plus three inner support must be optimized.In order to clarify validate the feasibility of the new supporting structure,the excavation process of the foundation pit using the original supporting structure and the new supporting structure was simulated,and then the obtained horizontal displacement,bending moment and surface subsidence were compared and analyzed.The test results showed that,the horizontal displacement,bending moment and surface settlement increased to some extent after if the pit support structure change to the form of large diameter cast-in-situ pile plus one inner support,but the stability of the foundation pit can still be ensured.The research results showed that the reduction of the support stiffness and the number of supports have a great impact on the maximum horizontal displacement and surface settlement,and deepen the location where maximum horizontal displacement occurs;however,it will not affect the ground surface subsidence law and the location of the maximum displacement.This research can be used for reference in similar foundation pit engineering.