砂岩单轴压缩与劈裂破坏过程的损伤研究

Sandstone Damage in Failure Process of Uniaxial Compression and Brazilian Split

在对赵固矿煤层顶板砂岩进行单轴压缩试验的基础上,结合颗粒流程序获得砂岩细观力学参数并采用编制的fish程序进行了单轴压缩和巴西劈裂试验,研究砂岩在压缩和劈裂破坏过程中的损伤演化机制。得到如下结论:压缩破坏在主控破裂面上接触力集中传递,在损伤区接触力向临近岩体转移,劈裂破坏中接触力在劈裂方向由圆盘边缘向内扩散,垂直劈裂方向由圆盘中心向边缘逐渐减小;压缩破坏砂岩损伤发展经历弥散分布、聚集成核、形成局部裂隙和宏观裂纹贯通失稳4个阶段;劈裂破坏中损伤分布在劈裂径向一定宽度范围内,微裂纹从受力复杂的圆盘边缘萌生沿着径向不断发展并突然贯通。

By obtaining the mechanical parameters through testing the sandstone of coal seam roof under uniaxial compression in Zhaogu mine and getting the meso-mechanical parameters by particle flow code(PFC)with fish program,sandstone damage evolution mechanisms in failure process of uniaxial compression and Brazilian split were studied. Some main research results show that contact force is transmitted concentratedly in master rupture surface and transfered to the adjacent rock mass in damage zone. It diffuses inwardly from the disc edge in the diameter direction and gradually decreases from the center to the disc edge in diameter vertical direction. The process of sandstone damage evolution in uniaxial compression failure can be divided into four stages as damage dispersion distribution stage,damage gathered in some zone stage,forming local cracks stage and macro-cracks causing rock failure stage. Sandstone damage in Brazilian split failure process is mainly distributed in a certain width range in splitting direction. Micro-cracks originate from the disc edge,evolve along the radial direction and cause sudden splitting failure.