用非连续变形分析方法模拟冲击荷载作用下巴西圆盘的破坏过程

 为研究岩石在冲击荷载作用下岩石的破裂过程，运用岩体裂纹扩展破坏二维分析程序DDARF(Discontinuous Deformation Analysis for Rock Failure)，对大理石巴西圆盘试样在分离式霍普金森压杆(SHPB-Split Hopkinson Pressure Bar)试验中动态破裂全过程进行了数值模拟分析研究。模拟结果形象展示了试样在不同入射波作用下裂纹的萌生、演化、扩展及贯通破坏情形，与试验结果有较好的吻合。对裂纹产生的力学机理、扩展过程及伴生现象做出了解释。研究结果表明：(1) 改进的微观破裂准则不仅适用于模拟岩石静载破裂，而且可以用于模拟动载破坏；(2) 巴西圆盘试样在受到冲击荷载作用时，主裂纹首先从一端产生，然后逐渐沿径向加载方向向中心延伸、扩展至另一端贯通破坏，裂纹尖端的拉应力是导致岩石开裂的原因；(3) 主裂纹拓展过程中伴随着次生损伤微裂纹的产生，次生微裂纹主要集中在主裂纹两侧附近区域；(4) 试样两端与入射杆、透射杆接触部分会产生三角形破裂区，且随着入射波幅值的增大，三角形破裂区域面积有增大的趋势。

NUMERICAL SIMULATION OF BRAZILIAN DISC SPECIMEN FAILURE UNDER DYNAMIC LOADING USING DISCONTINUOUS DEFORMATION ANALYSIS METHOD

To study rock dynamic fracture，the two-dimensional Discontinuous Deformation Analysis for Rock Failure(DDARF) is implemented to simulate the whole process of the Brazilian disc specimen dynamic fracture in the Split Hopkinson Pressure Bar(SHPB) experiment. It is concluded that the results reproduce the whole fracture process from the initiation，propagation to failure of the specimen under the different incident waves，which fits well with the experimental results. The fracture extension mechanism，crack propagation and concomitant phenomenon are explained. The results show that：(1) The improved micro-fracture criterion applies not only to simulate static load failure，but also to simulate the dynamic load failure. (2) When the sample subjected to impact loading，the main cracks initiate from one end，gradually extend to the center along the radial load direction and propagate together to the other end. The tensile stress at the crack tip is the cause of rock crack. (3) The propagation process of the main cracks is accompanied by the generation of the secondary damage micro-cracks that focus on the region near both sides of the main cracks. (4) The triangular fracture zone is generated in the contact part of both ends of the specimen，the incident and transmission bars and the zone has the tendency of increase with the increase of incident wave amplitude.