地铁车站一次扣拱暗挖逆作体系模型试验研究

基于地铁暗挖车站一次扣拱逆作结构的1∶20三跨的较大比例模型实验,通过严格按照实际开挖过程模拟,对围岩与结构的关键部位进行力学和变形连续测试,包括初期支护、二次衬砌、中柱、地层应力及地中和地表位移。实验表明:拱顶位移均受到各自导洞的开挖影响最大,约占其全部位移的一半;地表位移受导洞开挖影响最大,且随导洞增多而变大,当两侧的4个导洞都开挖完后,其位移大约为总位移的一半多;初衬应力有拉有压,表现为随测试部位的不同而有差异,初衬的临时竖向支撑和仰拱为压应力,拱腰部位为拉应力,在导洞开挖过程中,初衬基本表现为压应力,随着拆除中间支撑,初衬的力学性状转换为拉应力,直到二衬施工完毕后,拉应力变小;钢管柱是传递和承受荷载的主要部件。实验结果完善了设计理论,有利于促进该工法的进一步推广应用。

A Model Test Study on the Construction of Subway Station with a Single Arch and Reverse Excavation Method

Based on the large scale model experiment of 1:20 and 3 spans of the single arch deduction inverse structure of underground excavation station, the mechanical and deformation tests of key parts of surrounding rock and structure were carried out according to the simulation of the actual excavation process, including initial support, secondary lining, central pillar, formation stress and ground and surface displacement. The results show that the displacement of arch roof is affected by the excavation of each guide tunnel, which accounts for half of the total displacement. The surface displacement is most affected by the excavation of the guide tunnel, and it increases with the increase of the guide tunnel. When the four guide tunnels on both sides are completed, the displacement is about half of the total displacement. the initial lining stress is drawn and pressed, which is different with the test part. The temporary vertical support of the initial lining and the inverting arch are compressive stress. The axial part of the arch is tensile stress. During the excavation of the guide hole, the initial lining basically shows compressive stress. With the removal of the intermediate support, the mechanical properties of the initial lining are converted into tensile stress, and the tensile stress becomes small after the completion of the second lining construction. The steel pipe column are main components for transmission and load bearing. The experimental results improve the design theory and are conducive to the further promotion and application of the work method.