黄土地区浅埋暗挖地铁隧道衬砌受力分析

为了解黄土地区浅埋暗挖地铁隧道衬砌结构的受力特征，得出荷载在衬砌结构各部分中的分担比例，以西安地铁 2 号线实体工程为依托，开展了较大规模的现场测试工作，对围岩与初期支护接触压力、初期支护与二次衬砌接触压力及二次衬砌结构应力进行了研究。结果表明：在三连拱大断面地铁隧道中先开挖洞室初期支护各部位所受的围岩压力均大于后开挖洞室初期支护所承受的压力；左、右线中墙顶、底部初期支护承受的压力较大，表明隧道中隔墙承担了较大的上部土体荷载；初期支护与二次衬砌承受的荷载比例为 52.81% 和 47.19% ；二次衬砌混凝土基本受压，左、右中隔墙二次衬砌混凝土受压最大。在标准断面地铁隧道中左、右线墙脚位置初期支护与围岩之间接触压力较大，表明这两位置承受了大部分垂直压力；初期支护与二次衬砌承受的荷载比例为 40% 和 60% ；二次衬砌混凝土基本受压，拱腰及以上位置应力较大，仰拱处应力较小。

Mechanical characteristics for linings of shallow excavation metro tunnel in loess region

In order to precisely understand the mechanical characteristics for secondary linings of shallow excavation metro tunnels in loess region,large scale field tests are conducted at Xi'an metro line No.2 site.The contacting pressure on the surrounding rock and the initial support system,contacting pressure on the initial supports and secondary linings and the stress of the secondary linings are monitored.The test results indicate that the surrounding rock pressures of each part in the initial support in earlie...