张杰, 郭奇峰, 蔡美峰, 张英, 汪炳锋, 吴星辉. 循环扰动荷载作用下花岗岩中裂隙萌生扩展过程的颗粒流模拟[J]. 工程科学学报, 2021, 43(5): 636-646. DOI: 10.13374/j.issn2095-9389.2020.03.15.003
引用本文: 张杰, 郭奇峰, 蔡美峰, 张英, 汪炳锋, 吴星辉. 循环扰动荷载作用下花岗岩中裂隙萌生扩展过程的颗粒流模拟[J]. 工程科学学报, 2021, 43(5): 636-646. DOI: 10.13374/j.issn2095-9389.2020.03.15.003
ZHANG Jie, GUO Qi-feng, CAI Mei-feng, ZHANG Ying, WANG Bing-feng, WU Xing-hui. Particle flow simulation of the crack propagation characteristics of granite under cyclic load[J]. Chinese Journal of Engineering, 2021, 43(5): 636-646. DOI: 10.13374/j.issn2095-9389.2020.03.15.003
Citation: ZHANG Jie, GUO Qi-feng, CAI Mei-feng, ZHANG Ying, WANG Bing-feng, WU Xing-hui. Particle flow simulation of the crack propagation characteristics of granite under cyclic load[J]. Chinese Journal of Engineering, 2021, 43(5): 636-646. DOI: 10.13374/j.issn2095-9389.2020.03.15.003

循环扰动荷载作用下花岗岩中裂隙萌生扩展过程的颗粒流模拟

Particle flow simulation of the crack propagation characteristics of granite under cyclic load

  • 摘要: 从细观角度、采用颗粒离散元法开展了预制裂隙花岗岩循环加卸载的数值模拟试验。首先,使用图像处理技术识别花岗岩中的不同细观组分、结合室内单轴压缩试验结果对细观力学参数进行了标定。然后,通过编制颗粒流代码追踪裂隙的类型和扩展过程,分析岩石破坏过程中裂隙发展的阶段性特征。结果表明:不同倾角裂隙岩石的新生裂隙走向与预制裂隙贯通方向基本一致;根据新生裂隙的优势倾向分组得到裂隙起裂角与预制裂隙倾角的关系:倾角β≤45°时剪切和张拉裂隙的起裂角单调递减,倾角β≥60°时剪切和张拉裂隙的起裂角单调递增;循环扰动荷载增加了裂隙岩体的轴向变形,轴向累积残余应变曲线呈反S形、提高扰动荷载应力上限促使曲线进入加速阶段;试件峰值强度随裂隙倾角增大表现出先减小后增大的趋势,峰值强度为实验室完整岩石单轴抗压强度的63% ~ 89%,反映了较为明显的劣化现象;在循环荷载作用下,剪切裂隙和张拉裂隙增长曲线表现出明显的变化特点,在裂隙不稳定扩展阶段中张拉裂隙数目增长速率显著大于剪切裂隙,对分析岩石变形破坏过程具有一定的参考意义。

     

    Abstract: The microcracks in natural rock masses considerably impact the stability of the underground engineering structures. The mechanical properties of the cracked rock masses contribute considerably to the strength of the rock masses and their compression failure mechanism. The instability and failure of the surrounding rocks are often induced by the propagation and penetration of these internal cracks. In practical engineering, rock mass excavation is a process involving dynamic disturbance. The mechanical properties of the rocks under cyclic load are considerably different from those of the rocks under static load. The characteristics and development of microcracks are the main factors influencing rock fatigue failure. From the microscopic viewpoint, the particle-based discrete element method is used to conduct the cyclic loading and unloading tests of the preexisting cracked granite. First, the microcompositions of granite are determined using image processing techniques, and the micromechanical parameters are calibrated based on the indoor uniaxial compression test results. The stage of crack development during rock failure is analyzed by compiling particle flow code to track the type and propagation process of cracks. Results indicate that the orientations of new cracks in fractured rocks with different dip angles are similar to those of the preexisting cracks. Further, the relation between the crack initiation angle and the inclination angle of the preexisting cracks is obtained according to the tendency of new cracks. The crack initiation angle of shear and tension cracks decreases and increases monotonically, respectively, when the inclination angle β ≤ 45° and β ≥ 60°. The cyclic disturbance load increases the axial deformation of the fractured rock mass, and the axial cumulative residual strain curve exhibits an inverse S-shape when entering the acceleration stage faster with the increasing upper stress limit. The peak strength of the model specimen shows a decreasing trend followed by an increasing trend with the increasing fracture inclination. The peak strengths of the laboratory-intact rock are 63% to 89%, indicating an obvious deterioration phenomenon in the rock materials. The growth of shear and tension cracks show different characteristics under cyclic load; the growth rate of tension cracks is considerably higher than that of shear cracks during the unstable crack development stage. The results presented in this study may be used as reference to investigate the deformation and failure mechanisms of rock materials.

     

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