含雁列式断续节理的岩质边坡失稳机制模拟研究

SIMULATION STUDY ON INSTABILITY MECHANISM OF ROCK SLOPE WITH EN ECHELON DISCONTINUOUS JOINTS

岩质边坡的阶梯状破坏是一种常见的失稳破坏类型,其稳定性主要受岩质边坡内部的不连续结构面和岩桥控制。为了探究雁列式裂纹间相对位置的复杂变化对节理岩质边坡阶梯状破裂面形成的影响,基于零厚度黏聚力(Cohesive)单元,采用重力增加法开展了考虑裂隙倾角、岩桥倾角、岩桥长度的含雁列式裂纹岩质边坡阶梯状破坏数值模拟。通过对于模拟结果的编程处理,实现了节理岩质边坡破坏过程中的声发射模拟,结合岩质边坡破坏过程的应力、位移云图,进一步分析了节理岩质边坡阶梯状破裂面形成的演化过程与力学机制。研究表明:节理岩质边坡模型的破坏模式可分为持续破坏型和渐进破坏型,渐进破坏模式的出现主要与裂纹倾角和岩桥倾角有关;岩质边坡阶梯状滑裂面的形成是一个岩桥从下至上逐渐贯通的过程,其破坏过程分为等速变形阶段和加速变形阶段;随着裂纹倾角的增加,岩质边坡的岩桥贯通所需要的荷载逐渐增加;随着岩桥长度的增加,岩质边坡内部岩桥破裂贯通所产生的声发射事件数和裂纹扩展总长度逐渐减小;相比于裂纹倾角和岩桥长度,岩桥倾角对于节理岩质边坡中岩桥贯通与阶梯状破裂面形成的影响较小。本文研究了多种工况下含雁列式断续节理岩质边坡的失稳机制,以期为该类型岩质边坡的稳定性评价与失稳防控提供一定的理论参考。

The stepped failure of rock slopes is a common type of failure,primarily controlled by discontinuous structural planes and rock bridges within the rock slope.To investigate the influence of complex changes in the relative positions of en echelon cracks on the formation of stepped fracture surfaces on jointed rock slopes,numerical simulations of the stepped failure of cohesive rock slopes with en echelon cracks were conducted using the zero-thickness cohesive force element and the gravity increment method.The simulations consider factors such as crack dip angle,rock bridge dip angle,and rock bridge length.The simulation results were programmed to realize the acoustic emission simulation of the failure process of jointed rock slopes.By combining stress and displacement nephograms of the failure process of the jointed rock slope,the evolution process and mechanical mechanism of the formation of the stepped fracture surface of the jointed rock slope were further analyzed.The results indicate that the failure modes of the joint rock slope model can be categorized into continuous failure mode and progressive failure mode,with the emergence of the progressive failure mode mainly related to crack inclination angle and rock bridge inclination angle.The formation of the stepped sliding surface of the rock slope is a process of gradual connection of rock bridges from bottom to top,and the failure process is divided into equal velocity deformation stage and accelerated deformation stage.With the increase of crack inclination angle,the load required for rock bridge penetration of the rock slope gradually increases.As for the length of the rock bridge,the number of acoustic emission events and the total length of crack propagation caused by the fracture of the rock bridge in the rock slope gradually decrease.Compared with crack inclination angle and bridge length,bridge inclination angle has less influence on bridge penetration and step fracture surface formation in jointed rock slopes.This paper studies the instability mechanism of a rock slope with a wild goose discontinuous joint under various working conditions to provide theoretical references for stability evaluation,instability prevention,and control of this type of rock slope.