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为研究岩石在冲击荷载作用下的破裂过程,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试验中动态破裂全过程进行数值模拟研究。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,且与试验结果吻合较好。对裂纹产生的力学机制、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。
In order to study the rupture process of rock under the impact loading, a two-dimensional analysis program DDARF (discontinuous deformation analysis for rock failure) was used to test the marble Brazilian disc specimen in the split Hopkinson pressure bar SHPB test Dynamic Cracking the whole process of numerical simulation. The results of simulations show the initiation, evolution, propagation and failure of cracks under different incident waves, which are in good agreement with the experimental results. The mechanical mechanism, the process of expansion and the accompanying phenomena are explained. The results show that: (1) The improved microcrack criterion is not only suitable for simulating static load failure of rock, but also can be used to simulate dynamic load failure. (2) When a Brazilian disc specimen is subjected to impact loading, And then extend gradually to the center along the radial direction of loading, extending to the other end through the failure, the tensile stress of the crack tip is the cause of rock cracking; (3) the secondary crack growth process accompanied by the generation of secondary damage microcracks, Secondary microcracks are mainly concentrated in the vicinity of both sides of the main crack. (4) Triangular rupture zone occurs at the contact between the two ends of the specimen and the incident rod and the transmission rod. With the increase of incident wave amplitude, the area of triangular rupture area There is an increasing trend.