下穿地铁车站暗挖施工对既有线影响分析

Analysis of Influence of Underground Excavation on Existing Line under Subway Station

研究目的:近距离穿越既有线工程施工过程中,要保证既有隧道的安全运营,同时不破坏既有隧道结构安全性,这就要求施工对既有构筑物的影响减到最小,以保证工程施工和既有线运营的安全。本文结合北京地铁4号线宣武门车站超近距下穿既有2号线宣武门车站暗挖施工,分析开挖支护施工对既有线的影响。研究结论:(1)开挖支护施工对既有车站变形影响的控制效果总体良好,所有变形值未超出下穿既有车站施工目标控制值;(2)严格遵循对称原则,左右线同时、同步、对称进行;(3)型钢拱架能及时快速地对地层产生支护阻力,同时采取跟踪补偿注浆技术可达到主动控制沉降的目的,实践证明非常有效;(4)管棚注浆系统和既有结构底板的支撑作用显著;(5)本研究成果对城市地铁邻近既有线施工具有借鉴意义。

Research purposes： During the construction of close through existing lines at short distance,the safe operation of existing tunnels should be ensured,at the same time,the safety of existing tunnel structures can not be destroyed. This requires construction to minimize the effects of existing structures,to ensure the safety of construction and operation of existing lines. In this paper,the Beijing Subway Line 4 Xuanwumen station is under close cut through the existing 2 line Xuanwumen station,the influence of the excavation on the existing lines is analyzed.Research conclusions：（ 1） The control effect of excavation support on the deformation of existing station is overall good,and all deformation values do not exceed the target control value of the existing station;（ 2） The principle of symmetry should be strictly followed,left and right lines are carried out simultaneously,synchronously and symmetrically;（ 3） Steel frame can quickly and timely produce support resistance to formation,at the same time,taking tracking compensation grouting technology can reach the active control of the settlement,which proved very effective;（ 4） The supporting effect of the pipe roof grouting system and the existing structural floor is remarkable.（ 5） The results have reference significance for underground excavation on existing line under subway.