滚石坡面碰撞破裂效应的试验研究

Experimental study on fragmentation effects of rockfall impact upon slope

采用自主研发的滚石碰撞系统,试验研究滚石力学性质、碰撞速度、入射角度和滚石尺寸等因素耦合作用下的滚石坡面碰撞破裂机制,探讨碰撞破裂对滚石运动特征的影响。结果表明:滚石力学性质和碰撞速度是控制滚石碰撞破裂的主要因素,滚石力学性质越差,碰撞速度越大,滚石碰撞越破碎。滚石破裂存在法向速度阈值,随着力学性质的劣化,破裂法向速度阈值减小。碰撞入射角对滚石碰撞破裂及能量恢复系数影响较大;碰撞破裂不但会引起滚石总的能量恢复系数略有减小,而且会造成个别碎块具有较大速度,对防护结构构成不利影响。

A series of indoor impact tests were carried out by a self-developed rockfall impact testing system. The coupled effects of different factors, such as the rockfall mechanical property, the impact velocity, the incidence angle and the sample size, on the rockfall impact fragmentation mechanism and the rockfall trajectory characteristics were fully investigated. The results show that the mechanical property and the impact velocity are the two major factors that determine the rockfall fragmentation during the impact upon the slope surface. The fragmentation degree of rockfall increases with the growth of impact velocity while decreases with the improvement of rockfall mechanical property. Moreover, there is a normal velocity threshold beyond which the rockfall fragmentation occurs. The threshold decreases with the deterioration of rockfall mechanical property. Furthermore, the impact incidence angle will greatly influence both the rockfall fragmentation and the energy restitution coefficient. Fragmentation of rockfall due to the impact will not only slightly decrease the energy restitution coefficient but will also increase the velocity of some fragments, which may lead to adverse effects on the protective structure.