暗挖地铁车站施工通道与车站转换段施工方法研究
Construction methods at the intersection between Construction Channel and subway station

暗挖地铁车站转换段设计文件中通常采用门形爬坡法,然而由于这种方法转换步序较多,在实际工程中采用较少。基于已有工程经验,提出采用扇形扩挖法进行转换段施工。以重庆市凤天路地铁车站为依托,利用数值模拟研究门形爬坡法和扇形扩挖法2种施工方法的优缺点。着重对比2种施工方法所引起的围岩位移、应力分布,支护结构的受力状态,以及围岩的塑性区分布。研究结果表明:除支护结构最小主应力外,扇形扩挖法所引起的围岩变形、应力、支护结构应力及塑性区半径均小于门形爬坡法。将扇形扩挖法用于凤天路地铁车站转换段施工,转换段施工所消耗工期为20 d较门形爬坡法节约工期12 d,扇形扩挖法较门形爬坡法更有利于控制施工工期。因而,扇形扩挖法较门形爬坡法更适合暗挖地铁车站转换段施工。
The Door type climbing method is generally adopted in the conversion section between construction passage and subway station in design document. However, it is not widely used in engineering practice considering the complex switching process. Based on engineering experiences, the sector expansion method was put forward. Fengtianlu subway station in Chongqing, China was selected to compare these two construction methods through numerical simulation. Two three-dimensional numerical models were established corresponding to different construction methods, and the effectiveness of the established numerical model was validated through field monitoring displacement. Then the displacement and stress distribution of surrounding rock masses, internal force of supporting structures, and the radius of plastic zones were highlighted. Numerical results show that the displacement, stress, internal force of supporting structures, and radius of plastic zones induced by sector expansion method are all less than that induced by door type climbing method except for the minimum stress of supporting structures. The sector expansion method is used in Fengtianlu subway station. Consequently, the construction period is 20 days, and 12 days were saved compared to the door type climbing method. The sector expansion method is better in controlling construction period than the door type climbing method. It can be concluded that the sector expansion method is more suitable for construction in tunnel conversion section than the door type climbing method