隧道围岩变形及其衬砌内力特征研究

位于土层和岩层交界地层中的隧洞,其力学特性和水文地质条件均发生显著的变化,从而导致塌方或者围岩变形过大等。利用数值计算方法,建立二维有限元模型,对某工程隧洞土、岩接触地层中隧道开挖围岩变形和衬砌受力特性进行分析,并采用不同施工方法进行比较。结果表明,土、岩接触地层中隧道开挖围岩沉降位移场是非对称的,沉降位移最大位置在拱顶30°处,正是需要加强支护的位置;先墙后拱开挖在隧道三种施工方式中围岩最大沉降位移最小,正台阶开挖方法围岩沉降位移最大,留核心土开挖方法介于二者中间。合理的支护方式和开挖方式是土、岩层交界地层中隧洞周边岩体稳定的基本条件。

Research on Characteristics of Deformation of Surrounding Rocks and Internal Force in Lining Structures of Tunnel in Loess

The mechanical properties and geohydrological conditions of the tunnel in contacting stratum of soil and rock would vary remarkably so as to cause the callapse and the variation of surrounding rocks.Here,through the 2D finite element model established by the numerical calculation method, the deformation characteristics of surrounding rocks and the stressing properties of lining in the contacting stratum of a certain tunnel are analyzed and compared by using different construction methods.The results show that the settling displacement fields of the surrounding rocks in excavation of the tunnel are asymmetric,and the maximum displacement is at 30° of the arch crown,needing to be strengthened by supporting.And in three construction ways,the settling displacement of the surrounding rocks is smallest when using the excavation method with wall being first and arch being late,it is biggest when using the positive step excavation method,and it is between the both methods when using the excavation method with kern soil left.