冲击载荷下层状岩体动态断裂行为的模拟试验研究

摘要

By using specimens consisting of polymethyl methacrylate (PMMA) and epoxy resin,the dynamic three-point bending caustic experiments under impact loading were performed to study the fracture behaviors of layered rocks.The results are listed as follows.Cracking deviation happens on the bedding surface during the fracture process,which causes the crack not to develop directly through the surface along the original path.The offset is influence by the angle between the pre-existing crack and the bedding surface.With the angle increasing,the offset gets more.When the angle is less than 90°,only one deviation crack generates on the bedding surface.For the angle of 90°,two deviation cracks,of which the propagation paths are almost symmetric,generate on the bedding surface.The dynamic stress intensity factor Kd1 and propagation velocity v of crack tip decline gradually with the decrease of the distance between the bedding surface and crack tip,indicating that bedding surface shows crack resistance effect and such effect grows stronger with the the angle between pre-existing crack and the bedding surface.%采用有机玻璃和环氧树脂两种材料组成的试件模拟层状岩体,对层状岩体的动态断裂行为进行了动态焦散线三点弯曲冲击试验研究.试验结果表明,裂纹扩展到层理面时,不是直接穿过层理面沿原扩展方向继续扩展,而是产生一定的偏移后再继续扩展,其偏移距离与预制裂纹和层理面夹角有关,预制裂纹与层理面夹角越大,裂纹的偏移距离越大;当预制裂纹与层理面夹角＜ 90°时,裂纹穿过层理面后只产生一条偏移裂纹,而夹角为90°时,裂纹扩展至层理面后将产生两条偏移裂纹,并且这两条裂纹轨迹几乎对称;裂纹扩展过程中,随着裂纹尖端距层理面的距离减小,裂纹尖端动态应力强度因子Kd1和裂纹扩展速度v均逐渐减小,说明层理面对裂纹的扩展起阻碍作用,预制裂纹与层理夹角越大阻碍作用越大.研究结果对工程实践有重要的参考价值.