基于离散元方法斜碰落石冲击力的研究

落石灾害往往给交通基础设施、过往车辆、行人等造成极大地威胁。落石冲击力是落石灾害防护结构设计的主要荷载,因此,对落石冲击力进行深入研究能为防护结构的设计提供理论参考。本文对比分析了PFC3D模型与现有落石冲击力公式计算结果差异,并采用离散元程序,对落石不同半径、不同角度地冲击作用进行了数值模拟。结果表明：PFC3D离散元程序能够用于落石冲击力的计算；在冲击能量相同的情况下,落石斜碰作用冲击力不及正碰作用,当冲击角度α>50°时,斜碰作用冲击力与正碰作用冲击力相差变小；并且落石冲击力切向分量随着角度先增加后减小,角度越缓,落石冲击力主要由切向力控制。当斜碰垂直分速度与正碰速度相同的情况下,斜碰冲击角度越缓,落石冲击力反而越大,切向力占比越大。本文的研究结果可为落石斜碰作用下防护结构的设计提供参考。

The Research of Rockfall Impact Force with Oblique Impact Based on the Discrete Element Method

Rockfall disasters often pose a significant threat to transport infrastructure, passing vehicles and pedestrians. Impact force of rockfall is the main load of rockfall disasters precautions, so it is pretty deserving to have intensive study on impact force of rockfall. In this paper, it compares and analyzes the difference of computing results between the PFC3D pattern and the existing formula to compute impact force of rockfall,and uses discrete element program to carry out numerical simulation on the impact of rockfall with different radius and different angles. The results show that the PFC3D discrete element program can be used to calculate the rockfall impact force. When the impact energy is the same, the impact force of rockfall oblique collision is inferior to positive impact. When the impact angle is more than 50 °, the difference becomes smaller between the impact force of rockfall oblique collision and positive impact force; and when the tangential component of the rockfall impact force increases with the angle first, then decreases, and the angle decreases slowly, the rockfall impact force is mainly controlled by the tangential force. When the oblique collision is as same as the vertical collision speed, the impact angle of the oblique collision is slower and the impact force of the rockfall is greater, and the horizontal velocity has a certain enhancement effect on the falling rock impact force. The results of this paper can provide reference for the establishment of rockfall oblique contact force formula.