落石碰撞破碎概率及碎片分布特征研究

我国西南地区，尤其是川藏铁路沿线，存在大量高陡层状碎裂岩质边坡，致使落石灾害频发。由于高位落石与坡面碰撞速度大，崩塌后常发生剧烈破碎。破碎显著改变了落石运动轨迹，使得轨迹预测变得更加困难，导致难以设计合理的落石防护措施。因此，本项目以落石碰撞破碎为核心，考虑落石外形及内在节理两个关键因素，围绕落石碰撞破碎概率及碎片分布两个科学问题开展研究。本课题通过高陡层状碎裂岩质边坡原位地质调查，对落石外形及内在节理进行量化；通过落石碰撞破碎室内试验，揭示外形及内在节理对破碎概率及碎片分布的影响；基于碰撞破碎三维离散元精细模拟方法，开展落石碰撞破碎模拟，阐明破碎细观机理，并开展更复杂条件下落石碰撞破碎模拟。基于试验及模拟结果，建立碰撞破碎概率和碎片分布理论模型；基于提出的理论模型，开发考虑破碎的落石运动轨迹三维离散元快速分析方法，实现破碎条件下落石轨迹的准确预测，为防护措施设计提供合理依据。

Many high rock slopes with layered cataclastic structure exist in Southwest China, especially along the constructing Chuanzhang railway, which result in frequent occurrence of rockfall. The rockfall at high and steep rock slope has high impact velocity and thus the rockfall fragmentation is common. Rockfall fragmentation significantly changes rockfall trajectory, and the precise trajectory prediction and reasonable rockfall protection measures are more difficult. Hence, the study focuses on rockfall fragmentation, which refers to two questions-breakage probability and fragment distribution. The crucial factors of complex shape and internal discontinuities are considered. In this study, the in-situ geological surveys of rock slope and rockfall are conducted to analyze the complex shape of rockfall blocks and the discontinuities comprehensively and quantitatively; the laboratory tests are performed to indicate the effect of block shape and discontinuities on breakage probability and fragment distribution; through the proposed precise rock block fragmentation modelling method, the three-dimensional discrete element method simulations of rockfall impact are performed to reveals the fragmentation mechanisms, and simulations with more complex shape and internal discontinuities are conducted to supplements the laboratory tests; based on the laboratory and simulated results, the breakage probability and fragment size and velocity models are proposed; based on the proposed models, the fast three-dimensional discrete element method of rockfall trajectory considering fragmentation is developed. The accurate rockfall trajectory can be predicted through the proposed method, which provides a reasonable basis for the design of protective measures.