柱状岩体崩塌动力特征与破碎规律

柱状岩体崩塌具有分布范围广、破坏能力强、影响范围大的特点。2004年8月12号，重庆甑子岩W12危岩体发生崩塌，崩塌体运动距离约600 m，形成显著超前空气冲击效应，激起浮尘高度约150 m。文章基于MatDEM离散元软件对甑子岩崩塌动力特征与破碎规律进行了研究，建立了按照实际节理分布的崩塌模型，实现了崩塌全过程的模拟，并结合影像资料验证了模型的有效性，在此基础上对MatDEM进行二次开发，统计分析了崩塌过程中岩块粒径演化规律，确定了崩塌过程中的四个显著颗粒破碎时刻，分别为崩塌源区底部岩体受压破碎、中上部岩体撞击低速三角区、中部岩体撞击斜坡地面与上部岩体撞击斜坡地面。引入分形维数与双参数Weibull分布模型分析了崩塌前后颗粒破碎规律，结果显示崩塌后颗粒破碎明显，细粒颗粒占比显著增加。文章为岩体崩塌的动力特征与破碎规律的研究提供了依据。

Dynamic characteristics and fragmentation evolution of columnar rockfall: A case study of the Zengziyan rockfall in Chongqing,China

Columnar rockfall occur widely in China and cause extreme damage to man-made structures and facilities. On 12 August 2004, Zengziyan W12 perilous rock collapsed and ran out a horizontal distance of 600 m. The rockfall caused airblast with a height of 150 m. In this paper, the dynamic characteristics and fragmentation evolution is studied based on the discrete element software MatDEM. The simulation of the rockfall process is achieved based on the discrete element model with real distribution of joints. The simulation is valid by comparing the simulation and video data. Through deeper development on MatDEM, the rock size evolution is analyzed, it was found that there were four significant breakage moments during the rockfall. The moments are rock compression breakage at the bottom of the rockfall, collision breakage of middle-upper rock mass with low-velocity triangle area, collision of middle and upper part of rock mass with ground, respectively. The fragmentation evolution of the pre- and post- rockfall is studied based on the fractal theory and dual parameters Weibull distribution. The results show that the proportion of fine particles increase obviously after the rockfall. This paper offers the basis of dynamic characteristics and fragmentation evolution of other rockfalls.