陡倾结构面下小净距隧道开挖围岩受力特性分析

Analysis on mechanical characteristics of surrounding rock during excavation of small clear-distance tunnel with steep-inclined structural plane

针对在小净距隧道岩层中存在陡倾结构面时,将对隧道围岩的受力分布产生影响的问题。依托贵州余安高速里坪2号隧道工程,采用MIDAS GTS/NX有限元软件,对存在多组陡倾结构面岩层下的小净距隧道进行了模拟,并分析了隧道围岩受力特性。结果表明:由于拱顶存在应力释放和重力作用,再加上施工扰动,致使产生的位移量最大;拱顶的总体位移均大于拱腰处的总体位移,并且靠近中间岩体侧的总体位移大于远离中间岩体侧拱腰的总体位移;岩层中陡倾结构面倾角越陡,隧道中间岩体上应力越集中。研究结果与实际工程施工中围岩受力变形规律一致,可为小净距隧道采取安全施工措施提供指导。

In recent years,small clear-distance tunnel is more and more applied to the relevant project.When steep-inclined plane is there in the rock formation of small clear-distance tunnel,the stress distribution of the tunnel surrounding rock is to be affected.Relying on Liping No.2 Tunnel Project of Yuqing-Anlong Expressway in Guizhou Province,the small clear-distance tunnel crossing through the rock stratum with several groups of steep-inclined structural planes is simulated with the finite element software—MIDAS GTS/NX,and then the mechanical characteristics of the tunnel surrounding rock is analyzed.The result shows that due to the stress release and the gravity effect at the vault of the tunnel as well as the relevant construction disturbance,the displacement therein is the largest,thus the total displacement at the vault is larger than that at the hance of the tunnel,while the total displacement near the side of the intermediate rock mass is far larger than that at the hance far away from the side of the intermediate rock mass.The more steep the inclined angle of the steep-inclined plane in the rock stratum is,the more concentrated the stress on the intermediate rock mass is to be.The result is consistent with the stress and deformation law of surrounding rock during the actual construction of the project,and then can provide a reference for adopting the relevant safety measures for the construction of the small clear-distance tunnel.