基于武当群片岩各向异性试验的隧道围岩变形机理分析

Deformation Mechanism of Tunnel Surrounding Rock Based on an Anisotropic Test of the Wudang Group Schist

针对通省隧道拱顶出现纵向裂缝、拱肩钢拱架被剪断等变形破坏问题,文章考虑武当群片岩各向异性特点,基于波速试验、单轴压缩与三轴压缩试验,结合围岩变形特征调查与数值模拟试验,分析了武当群片岩试样应力-应变曲线特征与破坏形态特征,建立了弹性模量、泊松比、抗压强度随片理倾角从0°~45°~90°变化时的对应关系,提出了隧道围岩破坏模式,总结了隧道围岩变形机理。研究结果表明:武当群片岩各向异性在隧道围岩变形破坏过程中起到了控制性作用;非对称模式为隧道围岩主要破坏模式;当隧道围岩最大剪应力与片理空间关系不利时,围岩沿片理面发生剪切破坏。研究结果对武当群片岩区域在建或拟建地下工程的现场设计、施工开挖具有重要的指导意义。

The deformation and failure events that occurred in the Tongsheng tunnel resulted in longitudinal crack- ing in the crown and steel arch breaking at the spandrel. Considering the anisotropie characteristics of the Wudang group schist, the characteristics of the stress-strain curve and the failure pattern of samples of the Wudang group schist are analyzed based on the surrounding rock deformation properties, the numerical simulation, the wave veloci- ty test, the uniaxial compression test and the triaxial compression test. A corresponding relationship between the elastic modulus, Poisson＇s ratio and compressive strength versus the schistosity angle changing from 0~ to 45~ and 90~ is established, the failure mode of the tunnel surrounding rock is presented and the deformation mechanism of the tunnel＇s surrounding rock is summarized. The results show that the anisotropy of the Wudang group schist plays a controlling role in the process of deformation and failure of the tunnel＇s surrounding rock; the asymmetric mode is the main failure mode of the tunnel＇ s surrounding rock; and when the spatial relationship between the maximum shear stress of the tunnel＇s surrounding rock and the schistosity is unfavorable, the surrounding rock will shear along the schistosity plane.