散粒体斜坡上滚石法向碰撞恢复系数研究

Study on the Normal Restitution Coefficient of Rockfall Impaction Loose Granular Slope

国内外在研究滚石碰撞问题时多将碰撞目标假设为弹塑性体,从而推导出恢复系数计算公式。但是对于散粒体斜坡,由于具有结构松散、高压缩、低黏结力等物理力学特性,如果将其完全考虑为弹塑性体,那么低估了其自身的耗能潜力。为此,我们考虑了松散介质的孔隙压密特征,改进提出了散粒体斜坡上滚石法向碰撞恢复系数的计算式,并探讨了滚石碰撞再回弹的临界条件。同时以西藏昌都察达隧道进口散粒体斜坡为算例进行数值模拟,分析了5种影响因素下滚石法向碰撞恢复系数变化规律,并与改进公式、已有相关公式计算结果进行了对比分析。结果表明改进公式与数值模拟结果较为吻合,优于假设为弹塑性体的公式计算值。研究思路及成果可为类似区域性问题提供参考。

In the studies on rockfall impact problems in China and abroad,the impact target is com-monly assumed to be an elastic-plastic body,from which the calculation formula for the restitution coefficient is deduced.However,for granular slopes,due to their physical and mechanical properties such as loose structure,high compression,and low cohesion,treating them strictly as elastic-plastic bodies may underestimate their energy dissipation potential.In this paper,we considered the pore compaction characteristics of the loose medium,improved the formula for calculating the normal restitution coefficient of rockfalls on granular slopes,and discussed the critical conditions of rockfall impact rebound.At the same time,we took the granular slope at the entrance to the Chada tunnel in the Changdu area of Tibet as an example,carried out the numerical simulation,analyzed the variation law of the normal restitution coefficient of rockfalls under five influencing factors.We also compared the calculations of the refined formula with existing ones.The results show that the improved formula aligns well with the numerical simulation results,outperforming the calculation values derived from the elastic-plastic body assumption.The methodologies and results from this study may provide reference to similar problems of other regions.