岩层倾角对片岩隧道变形特征的影响

Influence of rock dip angle on deformation characteristics of schist tunnel

层状岩体的强度和变形具有显著的各项异性特征,隧道施工中围岩稳定性机理较为复杂,是隧道工程中的热点问题。为研究岩层倾角对围岩变形特征的影响规律,以中卫至兰州客运专线某大断面片岩隧道工程为依托,采用MIDAS进行了不同倾角下围岩稳定性数值分析,研究结果表明:层状岩体与各向同性岩体位移场差异性较大。对于各向同性岩体,隧道开挖后围岩产生向洞内的变形,位移场关于隧道轴线对称。对于层状岩体,围岩变形特征与岩层倾角相关,位移场关于层面法线方向大致呈现对称分布,隧道洞周测点位移不均匀性较大。岩层倾角对隧道围岩塑性区具有显著影响,岩层倾角不同,塑性区分布规律及面积均不相同,围岩稳定性差异较大。

The strength and deformation of layered rock mass have significant anisotropy characteristics,and the stability mechanism of surrounding rock in tunnel construction is relatively complex,which is a hot issue in tunnel engineering.In order to study the influence of rock dip angle on the deformation characteristics of tunnel surrounding rock,based on a large section tunnel project of Zhongwei to Lanzhou Railway,numerical analysis of surrounding rock stability under different dip angles was carried out by using MIDAS.The results show that:the displacement field of layered rock mass is quite different from that of isotropic rock mass.For isotropic rock mass,the surrounding rock will deform into the tunnel after excavation,and the displacement field is symmetrical about the tunnel axis.For layered rock mass,the deformation characteristics of surrounding rock are related to the dip angle of rock mass,the displacement field is approximately symmetrical in the direction of normal plane,and the displacement of measuring points around the tunnel is not uniform.The dip angle of rock strata has a significant effect on the plastic zone of tunnel surrounding rock.The distribution law and area of plastic zone area are different with different dip angles.The stability of surrounding rock is greatly different under different dip angles.