暗挖区间隧道下穿既有地铁施工技术

Construction Technology of Running Tunnel Driving with Mining Method Under Passing Existing Metro Structure

以新建深圳地铁7号线皇岗村站—福民站区间隧道下穿既有地铁4号线福民站为工程背景,首先分析了工程难点及应对措施,然后从地下连续墙拆除、深孔注浆加固、回填及补偿注浆、平顶直墙隧道施工4个方面阐述了下穿施工关键技术。经实施,全断面深孔注浆与工作面注浆相结合可以全面改良隧道岩土体,使得施工对既有车站结构的影响大大降低;在开挖及支护过程中,支撑钢架与既有车站结构底板密贴牢固;在加固过程中背后回填及补偿注浆可以减小车站结构变形沉降。监测结果显示各项变形值均小于控制值。

In this paper,the engineering background is Huangfu running tunnel of Shenzhen Metro Line 7.This new tunnel is under passing Fumin Station of Line 4,an existing line station.The construction difficulty and the corresponding measures were introduced.The key construction technology includes removing of concrete diaphragm wall,deep hole grouting for reinforcement,backfilling and compensating grouting technology,and flat topped wall tunnel construction.It shows that the combination of deep hole grouting at the entire section and grouting at the working section improves tunnel rock and soil,and mitigates the effect of tunnel construction on station structure significantly.During excavation and supporting process,the steel supporting frame shall be tightly attached to the bottom plate of the existing station.During reinforcement process,backfilling and compensating grouting alleviate structural deformation and settlement.The monitoring results show that all measured deformations are within the allowable values.