北京地区PBA法施工暗挖地铁车站地表变形分析

Analysis on Ground Surface Deformation of Mined Metro Station Constructed by PBA Method in Beijing

暗挖法施工的地铁车站大多处在繁华的中心城区,周边环境对变形非常敏感,为了减小施工对周边环境的影响,需对施工引起的地表变形规律进行研究,以便采取针对性的控制变形措施。结合北京地铁6号线一期及7号线PBA法施工暗挖车站,针对北京地区各典型地层条件及PBA工法特点,通过对现场监测数据进行统计分析,得出:1)PBA法施工暗挖地铁车站所引起的地表沉降主要发生在导洞施工及扣拱施工阶段,所发生的沉降约占总沉降量的90%;2)不同的地层采用PBA法施工所引起的地表沉降相差较大,根据施工所引起地表沉降由大到小依次为粉细砂及中粗砂层,粉土、粉质黏土层,圆砾-卵石层。

Metro stations are basically located in urban centers,thus the surrounding environments of the project is significantly complicated. In this context,ground surface settlement induced by construction of the Metro station is studied with respect to its influence on the surrounding environments,in order to select a rational settlement-control method. The monitoring data of mined Metro stations of Line No. 7 and Phase 1 of Line No. 6 of Beijing Metro are obtained for detailed analyses. The results show that： 1） The ground surface settlement induced by construction of heading and tunnel arch is of a large magnitude,accounting for 90% of the total settlement; 2） The settlement of different strata excavated by PBA method significantly varies. The settlement of fine-silt and medium-coarse sand strata is the largest,followed by that of silt and silty clay strata,and that of sandy-cobble strata is the smallest.