【摘要】 岩石破坏的本质原因是由于内部裂隙的萌生、扩展与贯通过程。从三维的角度出发,采用细观损伤数值模拟方法,模拟单轴压缩下含预制三维表面裂纹的岩石试样的破坏过程。数值模拟得到了表面裂隙内部扩展、贯通过程,动态再现翼型裂纹、壳体裂纹的形态,探讨三维裂纹内部的受力机制,推测可能发生的断裂类型,进一步探讨三维裂纹扩展规律。研究结果表明:①反翼型裂纹并不一定萌生于预制裂纹端部,是由于翼型裂纹扩展后应力释放后的拉应力引起;②壳体裂纹的萌生与扩展阶段是由Ⅲ型加载断裂主导,而翼型裂纹扩展至一定长度之后停滞不前;③除了反翼型裂纹之外,还新发现了一种由壳体裂纹萌生出的次生裂纹,这种裂纹的扩展引起试样整体失稳崩溃;④岩石Ⅲ型加载(反平面剪切)难以获得Ⅲ型断裂破坏,壳体裂纹是由于Ⅲ型加载下的拉应力引起,实际上属于Ⅰ型与Ⅱ型复合裂纹;⑤非均匀性对岩石表面裂纹扩展影响很大,相对均匀岩石中难以出现曲线翼型裂纹或反翼裂纹。研究结果对于岩石三维裂隙扩展机理的物理力学实验与理论分析都具有参考意义。更多还原

【Abstract】 Rock failure results from the process of internal crack initiation,propagation and coalescence intrinsically.A 3D numerical model based on the microscopic damage mechanics is employed to simulate the failure process of numerical rock specimens containing a pre-existing surface flaw subjected to uniaxial compression.The initiation,propagation and coalescence of wing cracks,shell cracks,anti-wing cracks and the secondary crack of shell cracks are reproduced in three-dimensional manner.Numerical results are obtained as follows:(1) anti-wing cracks are induced by the tensile stress after the stress release resulting from the propagation of wing cracks;(2) the shell cracks are predominated by III-type loading,and the wing cracks stop when they propagate ahead for a certain distance;(3) the secondary cracks of the shell cracks lead to the collapse of the whole specimen;(4) III-type fracture could not be obtained by III-type loading in rocks,and the shell cracks are induced by tensile stress in III-type loading;(5) due to the heterogeneities in rocks,it is difficult to find curved wing cracks and anti-wing cracks.The numerical results will be a good supplement of experimental investigation of surface flaw.The numerical code is proved to be a satisfactory tool to investigate the rock fracture in three-dimensional manner.更多还原