Abstract. Fracturing and fragmentation of rock blocks are important and universal phenomena during the propagation of rock avalanches. Here, the movement of a rectangular rock block characterized by different joint sets along an upper inclined and lower horizontal traveling path is simulated, aiming to quantify the fracturing and fragmentation effect of the block in propagation. The preset of the joint sets allows the block to break along the weak joint planes at the very beginning of fragmentation. With this design, the fracturing and fragmentation processes in the sliding rock block and their influences on energy transformation in the system are investigated. The results show that fragmentation can alter the horizontal velocities and kinetic energies of fragments in the block system with the front subblocks being accelerated and the rear part being obviously decelerated. Such energy conversion and transfer between the front and rear subblocks is attributed to the elastic strain energy release and transformation caused by fragmentation. The energy transfer induced by fragmentation is more efficient than that induced by collision. A positive trend between the kinetic energy increase of the front subblocks induced by fragmentation and the rock strength can be fitted well with a linear function. However, no good relationship is reached between the strain energy incremental ratio and travel distance, which implies that the fragmentation effects may be weakened with the increasing complexity of the fragmenting rock mass system. Three elastic strain wave release effects caused by rock fragmentation are further inferred and discussed based on simulation results.

中文翻译：

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岩体运动中岩石块的破裂和破碎引起的多尺度效应：对岩石雪崩传播的影响

摘要。岩石雪崩的传播过程中，岩石块的破裂和破碎是重要的普遍现象。在此，模拟了以不同节理集为特征的矩形岩石块沿上倾斜和下水平行进路径的运动，目的是量化块在传播过程中的破裂和破碎作用。关节组的预设允许块在断裂的最开始沿弱的关节平面破裂。通过这种设计，研究了滑动岩块中的破裂和破碎过程及其对系统能量转换的影响。结果表明，碎裂可以改变块状系统中碎片的水平速度和动能，其中前子区块被加速，而后子区块则明显地被减速。前后子块之间的这种能量转换和传递归因于由断裂引起的弹性应变能的释放和转换。由碎片引起的能量转移比由碰撞引起的能量转移更有效。线性函数可以很好地拟合由破碎引起的前子区块动能增加与岩石强度之间的正趋势。但是，应变能增量比与行进距离之间没有很好的关系，这意味着随着破碎岩体系统复杂性的增加，破碎作用可能会减弱。根据模拟结果，进一步推断和讨论了由岩石碎裂引起的三种弹性应变波释放效应。