台阶法开挖黄土隧道围岩变形规律

Analysis on the surrounding rock deformation of the loess tunnel terrace construction excavating

黄土隧道开挖中的变形与稳定是重要的工程问题,为探索黄土隧道台阶法施工中的围岩变形规律,以巴准铁路敖包沟隧道出口段的施工为例,采用数值模拟和现场实测对敖包沟隧道台阶法施工过程进行了分析,为隧道支护与加固提供依据。研究表明,拱顶下沉与水平收敛在隧道上台阶开挖后变形较大,地表沉降槽影响范围主要集中在距隧道中线20m范围内,且地表沉降主要由上台阶开挖引起,从拱顶到地表的地层沉降规律是沉降值从拱顶到地表呈由大到小,变化为先急后缓的曲线分布态势。

The surrounding rock deformation rule of the loess tunnel terrace construction is very important. Using the method of value simulation, we analyzed the Ao Bao ditch tunnel terrace construction process.Our results showed that the deformation of the arch submersion and the level restraining were growing with the tunnel terrace construction excavating. The surface subsides mainly occurred from 20 m inside the tunnel median line scope. The surface subsidence was resulted from the excavation on the stairs The sub- sidence values from the arch to the surface stratum changed from large to small.