地下车站轨排井围护结构和主体结构设计研究

The Design of the Supporting Structure and the Main Structure of a Metro Station Rail Shaft

地铁建设过程中需在部分车站设轨排井,该开孔受吊装钢轨的要求,铺轨阶段在较长范围内不能设内支撑,造成开孔范围内围护结构悬臂,且大开孔造成孔边应力集中较严重。与常规的地下二层车站设轨排井不同,地下单层车站设轨排井引起的围护结构悬臂长度和孔边水土压力较大。根据工程及水文地质概况,围护结构设计拟采用双排围护桩刚架结构,以保证基坑自身和周边建筑的安全;主体结构设计拟在孔边设加强暗梁,建立三维模型计算确定结构尺寸,与二维模型相比有利于工程安全和节约造价。数值分析结果和实践表明,本站轨排井位置围护结构和主体结构设计经验可行,相关计算方法及参数选取为相似工程的设计与施工提供参考。

Rail shaft is a vertical rectangular opening from the ground surface to the metro level and is necessary in some of the metro stations in order to lift the rail tracks to the metro elevation. The rail shaft requires that no internal support can be in stalled during the metro track installation. I.arge cantilever arm is required and the stress concentration is also identified ira this opening. Different from the supporting structure for the rail shafts for the conventional double story metro stations, the sup- porting structure for the rail shaft for the single layer has large cantilever arm and higher pore pressure. In order to ensure the safety of the rail shaft and the adjacent structures, the supporting structure utilized double row of HP piles in cased in the cast- in-place concrete columns based on the subsurface conditions. The stiffener beam was installed at both sides of the opening. Further, the sizes of the structures are determined throughout the three dimensional numerical analysis models since the three dimensional model has a better results in the safety and cost aspects over the two dimensional model. Both the numerical analy sis and the construction monitoring results demonstrated that both the supporting structure and the main structure design were successful