循环冻融作用下隧道缓倾角岩层损伤特性及致灾机制研究

高寒区隧道穿越缓倾角岩层时，冻胀力反复作用于岩体层理面上造成疲劳损伤，严重影响其稳定性，探明循环冻融作用下隧道缓倾角层状围岩的致灾机制是预防灾变发生亟需解决的工程问题之一。本项目以哈尔滨至牡丹江高速铁路控制性工程—虎峰岭隧道为研究背景，首先对经历多次冻融循环后的缓倾角层状岩体进行单轴循环加卸载试验，阐明冻融循环作用、岩体各向异性和循环加卸载条件等因素对缓倾角层状岩体损伤特性的影响效应。其次，研究缓倾角层状岩体疲劳破坏强度与冻融次数、层理倾角的关系，同一加载应力级别下、不同加载应力级别之间对应的滞回环形态特征，以及循环荷载作用对缓倾角层状岩体塑性形变的影响，构建循环冻融作用下缓倾角层状岩体的疲劳损伤本构模型。最后，着重研究高寒区隧道围岩的疲劳破坏问题，揭示循环冻融作用下隧道缓倾角层状围岩的致灾机制，为高寒区典型缓倾角岩层隧道灾害防治与设计施工提供理论支持。

When the tunnel passes through the low–angled layered rock strata in the alpine regions, the frost heave force repeatedly acts on the bedding surface of rock mass, causing fatigue damage and seriously affecting its stability. Study on the disaster–resulting mechanism of low–angled layered rock mass under freeze–thaw cycles is one of the most important engineering problems to be solved urgently in the prevention of the catastrophic accident. Relying on the Hufengling tunnel of the Harbin–Mudanjiang high–speed railway in China, this project first carried out uniaxial cyclic loading and unloading test for low–angled layered rock mass after multiple freeze–thaw cycles to clarify the effects of freeze–thaw cycles, rock anisotropy and loading and unloading conditions on cumulative damage of low–angled layered rock mass. Then, the relationship between the fatigue failure strength of low–angled layered rock mass with different bedding angles and freeze–thaw cycles, the shape characteristics of hysteresis loops corresponding to the same loading stress level and different loading stress levels, and the influence of cyclic loading on the plastic deformation of low–angled layered rock mass are studied. The fatigue damage constitutive model of low–angled layered rock mass under freeze–thaw cycles is established. Finally, this project focuses on the fatigue failure of tunnel surrounding rock in the alpine regions, reveals the disaster–causing mechanism of low–angled layered rock mass under freezing–thawing cycles. The research results can provide theoretical support for disaster prevention and design and construction of typical low–angled layered rock mass tunnel in the alpine regions.