富水条件下地铁出入口部分主体结构下沉改造关键技术

北京地铁2号线鼓楼大街站西北出入口通道与污水管线位置冲突，导致已完成的明挖结构需进行下沉改造。采用桩间止水帷幕及基底加固等措施，解决了富水条件下出入口明挖段加深改造围护桩嵌固深度不够的问题，确保了改造时基坑的安全； 通过防水方案优化及接缝处理等措施，解决了新旧防水结合的问题，实现了新旧结构的良好过渡，确保了施工质量。

Key Technologies for Lowering of Structure of Entrance/exit Passage Tunnel of Metro Works Located in Water-rich Conditions

The northwest entrance/exit passage tunnel of Guloudajie station on Line 2 of Beijing Metro is constructed by cut and cover method. However, due to the conflict between the completed passage tunnel and the existing sewage pipe line, the passage tunnel has to be lowered. Waterproofing curtain is installed between the piles of the open cut passage tunnel and the floor base of the passage tunnel is consolidated by means of jet grouting piles, which ensures the safety of the foundation pit during the renovation. The waterproofing scheme is optimized and the joint is well treated, which ensures the waterproofing effect of the works.