类节理岩石直剪试验力学特性的数值模拟研究

节理岩体的剪切特性是主导岩体工程稳定性的关键因素。基于PFC2D离散元颗粒流程序，结合室内试验结果对比分析，选取合理的细观参数进行数值模拟，分别从细观角度研究了节理岩石的裂纹发展、能量转化及声发射现象等特性，从宏观角度研究了节理岩石的强度模型和破坏形态。结果表明：节理岩体主要呈现磨损和剪断两种破坏形态，不同的破坏形态对应不同的强度模型；随着剪切变形增加，岩体沿节理面发生破坏，弹性阶段以法向裂纹为主，而塑性阶段切向裂纹起主导作用，滑移区R、P裂纹贯通形成破碎带，节理面产生较大滑移；在应力达到峰值强度前，边界能主要转化为应变能，法向裂纹生成较多；越过峰值强度后，摩擦能快速增长，并伴随大量切向裂纹产生。与室内试验结果相比，PFC2D较好地模拟了节理岩体剪切力学特性，弥补了室内试验中无法进行细观特性研究的缺陷，对于节理岩体后期研究提供了一些参考。

Numerical simulation of mechanical characteristics of jointed rock in direct shear test

The stability of rock engineering is strongly dependent on the shear strength of jointed rock mass. Based on the particle flow code (PFC2D), the reasonable mesoscopic parameters are selected in combination with experimental results to analyze the meso-properties of crack propagation, energy transmission, and acoustic emission phenomenon of jointed rock. The strength models and failure patterns of jointed rock are numerically simulated. The main research results are summarized as follows. Abrasive and shear failure patterns heavily exist in jointed rock, and different failure patterns are corresponding to different strength models. Rock mass is damaged along joint plane with the increase of shear deformation. Normal cracks prevail within elastic stage, whereas shear cracks dominate along the rough surface within plastic stage. The joint plane slides owing to appearance of crushed zone induced by the coalescence of R and P cracks. Boundary energy is mainly converted into strain energy and more normal cracks are generated prior to the peak shear strength. With the increase of shear stress, the friction energy grows rapidly and a large amount of shear cracks are produced at the same time. Compared with experiments, PFC2D can be used to simulate the shear properties of jointed rock mass well, which remedies the challenge of simulating behaviors of jointed rock at meso-scale in the laboratory test and provides a useful reference for further research on direct shear tests of jointed rock mass.