地铁车站洞桩法施工方案对比研究

Study for Comparison of PBA Construction Schemes of Subway Station

以北京地铁7号线桥湾站工程为背景,采用FLAC3D数值模拟的方法,通过监测数据分析不同洞桩法(PBA工法)施工对地表沉降和初支受力的影响,以确定PBA工法施工地铁车站的最优方案。研究分析表明:开挖1层导洞的施工方法能控制地表沉降且地表影响范围较小,但开挖车站底部时的隆起较大;开挖双层导洞的顶拱初期支护弯曲应力稍大;导洞开挖阶段和扣拱阶段占地表总沉降量的90%左右,其他阶段引起的沉降较小。

In order to select the optimal scheme of PBA construction schemes,numerical simulation of FLAC3 Dwas used based on subway station of Beijing Subway Line 7. Combining with monitoring results,the impact on settlement of ground surface and primary support force during different PBA construction schemes is analyzed. Results are as follows that a layer of pilot tunnel excavation construction method can control the surface subsidence and the surface influence range is small,but the uplift is large when excavated at the bottom of the station. Arch bending stress of double pilot tunnel excavation primary support was larger. Pilot tunnel excavation and buckle arch phase accounts for about 90% of the total surface subsidence,subsidence caused by other stage was small.