暗挖车站地下连续墙施工地表沉降分析

Analysis on the Ground Settlement in the Construction of Diaphragm Wall of Subway Excavated Stations

工程建设中地下水资源保护问题一直是社会各界关注的焦点。以国内首例城市地铁PBA暗挖车站边导洞内施工地下连续墙止水工程为依托,采用MIDAS/GTS NX软件重点模拟了导洞内地下连续墙施工前、施工中及施工后的地表沉降变化规律,并与现场监测数据进行对比分析。结果表明:1)地下连续墙施工前,地表沉降曲线以车站中线为中心,呈明显对称的沉降槽形式分布;2)地下连续墙施工中,单侧地下连续墙施工完成,其上方地表附近沉降影响最为明显,地表沉降量增量约占总沉降量的25%;3)左右两侧地下连续墙施工完成后,地表沉降量增量曲线类似W型;4)左右侧地连墙分别施工6幅以后,上方地表处沉降趋于稳定,沉降速率基本保持不变。

The protection of groundwater resources has always been a focus in engineering construction.This analysis is based on an underground diaphragm wall water stop project,which is the first construction in the side pilot tunnel of PBA underground excavation station of urban subway in China.MIDAS/GTS NX software is used to simulate the ground settlement changes of the diaphragm wall construction in the pilot tunnel,including before construction,during construction and after construction,and the results are compared with the actual field monitoring data.The results show that:(1)before the construction of the diaphragm wall,the center line of the surface settlement curve is the center line of the station,and the distribution of the curves is obvious symmetrical settlement groove.(2)During the construction of diaphragm wall,when the construction of one-sided diaphragm wall is completed,the settlement near the surface above is the most obvious.The maximum increment account is about 25%of the total settlement.(3)After the construction of diaphragm wall on the left and right sides,the incremental curve of surface settlement amount is similar to W-type.(4)After the construction of 6 diaphragm walls on the left and right sides,the settlement on the surface above tends to be stable,and the settlement rate basically remains unchanged.