深埋炭质板岩地层穿塌腔隧道开挖方法研究分析

Research and analysis on excavation method of deep-buried carbonaceous slate tunnel through cavity collapse

以峨(峨眉)汉(汉源)高速金口河隧道为工程依托,针对炭质板岩地层深埋段隧道施工过程中面临的拱顶塌腔问题,剖析塌腔形成原因,并基于现场地层条件及实际施工情况,进行数值模拟分析,研究分析分别采用二台阶预留核心土法及三台阶预留核心土法时的围岩位移及支护受力变形情况。结果表明:采用三台阶预留核心土法进行施工,相对二台阶预留核心土法,可降低10.6%的竖向位移及35.6%的水平位移,同时可降低22.9%的初期支护位移,但在一定程度上会使初支应力增大,综合考虑,围岩较差且对及时支护要求高的工程可优先采用三台阶预留核心土法进行施工。

Based on the project of Jinkouhe Tunnel of the Ehan Expressway,this paper analyzes the causes of cavity collapse at the vault in the deep buried section of the tunnel in the carboniferous salte stratum,and carries out numerical simulation analysis based on the site formation conditions and actual construction conditions,to study and analyze the displacement of surrounding rock and the stress and deformation of support when the two-step reserved core earth method and the three-step reserved core earth method are used respectively.The results showed that:Compared with the two-step reserved core earth method,the three-step reserved core earth method can reduce the vertical displacement by 10.6%and the horizontal displacement by 35.6%,and the initial support displacement by 22.9%.However,the initial support stress will increase to some extent.The three step reserved core earth method can be used preferentially for the projects with poor surrounding rock and high demand for timely support.