共面断续岩桥直剪试验破坏过程研究

岩桥对岩质边坡稳定性起控制性作用,而非贯通性节理岩体是广泛存在于岩质边坡中的一种岩桥载体形式。研究共面断续岩桥连通率对岩石抗剪性能的影响,可为岩质高边坡稳定性评价提供理论依据。以直剪试验的形式,通过石英砂、水泥、石膏和水制备直剪试验试样, 并预留相同长度的3条共面断续节理,对共面断续岩桥进行剪切模拟,分析其破坏模式、破坏过程演化机制和力学参数。结果表明:直剪试样呈现张拉破坏、拉剪破坏和剪切破坏3种破坏模式,以剪切破坏为主,节理所在面为控制性结构面;试样破坏过程依次呈现为裂纹稳定、裂纹破坏和残余变形阶段;随连通率增大,抗剪强度降低,黏聚力减小,内摩擦角小幅变动;共面断续岩桥连通率越大,岩石抗剪性能越差,岩质边坡稳定性越低。

Failure Process of Coplanar Discontinuous Rock Bridgein Direct Shear Test

Rock bridge plays a controlling role in rock slope stability, and non-penetrative jointed rock mass is a kind of rock bridge widely exists in rock slope. The purpose of this paper is to provide theoretical basis and experience for the stability evaluation of high rock slope through investigating the influence of connectivity rate of coplanar intermittent jointed rock bridges on the shear properties of rock.The failure mode,the evolution mechanism of the failure process and mechanical parameters of coplanar intermittent jointed rock bridge are analyzed by direct shear test.Three coplanar intermittent joints of the same length are reserved on test samples prepared with quartz sand,cement, gypsum and water.Results showed that tension failure,tension-shear failure and shear failure are failure modes of the samples,among which shear failure is the dominant one.The joint planes are the controlling discontinuities.Samples experienced three phases of failure: the steady development of cracking, the coalescence failure of discontinuous joints, and the residual strength stage. With the increase of connectivity rate,the shear strength and cohesion of sample reduced,and internal friction angle changed slightly.The larger the connectivity rate of the coplanar intermittent jointed rock bridge,the worse the shear performance of rock,and the lower the stability of rock slope.