团块缺陷结构对岩石静动力学特性影响的数值模拟分析

NUMERICAL SIMULATION FOR MECHANICAL PROPERTIES OF ROCK WITH BLOCK MASS UNDER STATIC AND CYCLIC LOADINGS

基于颗粒流离散元法和PFC^(2D)程序构建含团块缺陷结构的岩石数值模型试样,指定试样中部1 cm半径范围为团块缺陷,通过0.1倍、1倍和10倍关系改变团块细观力学参数,构建A、B和C三种数值试样类别,分别进行三轴压缩和三轴疲劳试验。通过试样破坏特征、强度特征、团块及周边应力、应变率特征分析缺陷岩石静、动力学特性。试验结果表明,压缩和疲劳荷载下A类试样在团块左右方向应力集中,而上下方向(包括团块内部)为低应力区;C类试样与之相反,B类试样无明显应力集中现象。无论压缩或疲劳荷载,A类试样团块应变率高于四周,C类试样与之相反,B类试样无明显应变率差异化。研究成果揭示:1)岩石内部团块状缺陷结构无论其材料强度高低均劣化岩石抗压强度;2)静动荷载加载过程中含团块缺陷岩石内部表现出应力场不均匀性和应变差异性。

Based on a particle flow discrete element model and PFC2D code, a numerical rock sample with block mass of 1 cm in radius located at the middle was built. Three sample types （A, B and C） were constructed by changing block mass micro-mechanical parameters with 0.1, 1 and l0 times, respectively, and all samples were conducted a triaxial compression test and a triaxial fatigue test. Their mechanical properties were studied through investigating rock fracture as well as measuring stress and strain ratio. The results show that： stress concentration is triggered above and below the block in the A-type sample under triaxial compression test and triaxial fatigue test loadings, while the low stress regions are located at the left and right side of the block mass. No stress difference is observed in the B-type sample. The amplitudes of strain ratio in block mass of the A-type sample is larger than that of the around, while the C-type sample is contrary. No strain ratio difference is observed in the B-type sample. The study reveals that 1） block mass with no matter high or low strength reduces to rock compression strength; 2） rock with block mass presents both non-uniform stress and deformation fields under static or cyclic loading.