不同含水状态下层理灰岩变角剪切力学特性及微震信号特征研究

Variable-angle shear mechanical properties and microseismic signal characteristics of bedded limestone under different water-bearing states

摘要

【目的】顺层岩质滑坡的稳定性及其破坏模式与层状岩体剪切力学行为密切相关，为深入揭示其相关内在机理，聚焦于探讨不同剪切角度与含水状态对层理灰岩剪切力学行为的影响。【方法】采用变角剪切试验，结合数字图像相关(DIC)与微震监测技术，对天然与饱和两种含水状态下不同剪切角度(30°~60°)的层理灰岩试样进行分析，系统研究其力学特性、应变场演化过程及微震信号特征。【结果】结果表明：(1)随剪切角度增大，试样峰值剪应力、法向应力及剪切应力均逐渐降低，且破坏模式由试样岩石基质剪断向试样层理面滑移转变；(2)在较低剪切角条件下，试样易形成剪切-张拉复合型破裂，破坏形态较为破碎，随着剪切角增大，法向应力作用减弱，破坏模式逐步转化为以沿层理面剪切为主导的单一滑移模式；(3)天然状态下微震活动呈现“活跃-平静-前兆-主震”的清晰序列，信号峰值高，表现为典型脆性破坏；而饱和状态下水分润滑作用使微震活动持续活跃，但信号峰值明显降低，具有由脆性破坏向塑性破坏转化的微震信号特点；(4)剪切角度主导了层理灰岩试样变形破坏模式的宏观表现，低角度下活动分散，累积计数高，高角度下微震前兆信号集中，平静期显著，破坏更具突发性。【结论】研究成果通过揭示不同含水状态下层理灰岩变角剪切力学特性及微震信号特征，为降雨作用下顺层岩质边坡稳定性评价与灾害预警提供了理论与数据支撑。

Abstract

[Objective] The stability and failure modes of bedding rock slopes are closely related to the shear mechanical behavior of layered rock masses. To thoroughly reveal the underlying mechanisms, the effects of different shear angles and water-bearing states on the shear mechanical behavior of bedded limestone are investigated. [Methods] Variable-angle shear tests were conducted, combining with digital image correlation(DIC) and microseismic monitoring techniques, on bedded limestone specimens under both natural and saturated water-bearing states at different shear angles(30°~60°). Their mechanical properties, strain field evolution, and microseismic signal characteristics were systematically studied. [Results] The result demonstrated that:(1) with increasing shear angle, the peak shear stress, normal stress, and shear stress of the specimens gradually decreased, while the failure mode transitioned from shear fracture of the rock matrix to slip along the bedding planes.(2) At lower shear angles, the specimens tended to develop shear-tensile composite fractures with relatively fragmented failure patterns. As the shear angle increased, the effects of normal stress weakened, and the failure mode gradually transformed into a single slip mode dominated by shear along the bedding planes.(3) Under the natural state, microseismic activity exhibited a clear sequence of “active-quiet-precursor-mainshock” with high signal peaks, indicating typical brittle failure. Under the saturated state, the lubricating effects of water caused microseismic activity to remain continuously active, but the signal peaks were significantly lower, demonstrating microseismic signal characteristics of a transition from brittle to plastic failure.(4) The shear angle dominated the macroscopic deformation and failure mode of bedded limestone specimens. At lower angles, microseismic activity was dispersed with high cumulative counts, while at higher angles, microseismic precursor signals became concentrated with a significant quiet period, [Results]ing in more sudden failure. [Conclusion] The research findings provide theoretical and data support for stability evaluation and disaster early warning of bedding rock slopes under rainfall conditions by revealing the variable-angle shear mechanical properties and microseismic signal characteristics of bedded limestone under different water-bearing states.

关键词

层理灰岩 / 变角剪切 / 剪切角度 / 含水状态 / 力学特性 / 微震信号特征 / 降雨 / 灾害预警

Key words

bedded limestone / variable-angle shear / shear angle / water-bearing state / mechanical properties / microseismic signal characteristics / rainfall / disaster early warning

基金资助

国家自然科学基金项目(42367022)

贵州省科技计划项目(黔科合支撑[2023]一般127)

贵州省科技计划项目(黔科合基础-ZK[2023]一般066)