暗挖车站洞内地下连续墙施工导洞环境效应分析

随着城市地铁建设的迅猛发展,地铁工程建设中车站开挖大面积抽降水作业与国家保护地下水资源政策的矛盾日益突出,亟需寻求适用于地铁车站开挖的非降水止水方式。以北京地铁16号线在施暗挖车站——看丹站为依托,对其采用的洞内地下连续墙止水措施导致的环境效应开展了深入探讨。由于地下连续墙在暗挖车站局促空间内的施作尚属首例尝试,因此重点聚焦于揭示地下连续墙施工引起的导洞拱顶沉降、水平净空收敛和应力分布的变化规律。数值模拟结果表明:地下连续墙施工主要引起导洞拱顶沉降的变化,导洞水平净空收敛较为稳定;地下连续墙施工前,导洞初期支护拉应力主要在导洞拱顶处和侧壁底角处。地下连续墙施工完成后,拉应力分布范围扩大,左右边导洞初期支护底板处扩大最为明显,向地下连续墙处大致呈条带状延伸。

Analysis of Environmental Effect of Pilot Tunnel for Diaphragm Wall Construction in Excavated Stations

With the rapid development of urbanization in China, the construction of urban subway has been developing rapidly. The contradiction between the large area dewatering operation of station excavation and the national policy for groundwater protection is becoming increasingly prominent in the construction of subway project. Therefore, it is urgent to find the method of non-precipitation construction in the construction process of metro station. The Kandan Station of Beijing Metro Line 16 was selected as the engineering background, the profound discussion on the environmental effects caused by first diaphragm wall water stop project in the side pilot tunnel was carried out. The construction method of the diaphragm wall in the confined space of the underground excavated station is the first case in China, the focus is on revealing the change law of the settlement of the pilot tunnel vault, horizontal clearance and tensile stress distribution range. The numerical results show that the construction of the diaphragm wall mainly causes the change in the settlement of the pilot tunnel vault, and the horizontal clearance of the pilot tunnel is relatively stable; before the construction of the diaphragm wall, the initial tensile stress of the pilot tunnel is mainly at the pilot tunnel vault and the bottom corner of the side wall Place. After the construction of the diaphragm wall is completed, the tensile stress distribution range is expanded, and the expansion of the initial support floor of the pilot tunnels on the left and right sides is the most obvious, extending roughly in a strip shape to the diaphragm wall.