摘要
法向恢复系数取值是落石运动路径计算的关键参数。利用高速摄像机拍摄不同坡面铺装、不同坡度、不同下落高度、不同落石质量和形状试验条件下落石碰撞坡面的过程,提取落石碰撞坡面前后落石的运动参数,据此反算法向恢复系数,得到如下规律:坡面铺装和坡度是法向恢复系数的主要影响因素,落石的形状和质量以及下落高度对法向恢复系数的影响不明显;随坡面由硬到软,法向恢复系数逐渐减小;随着坡度的增大,法向恢复系数逐渐增大;由试验数据计算所得各种试验条件下的法向恢复系数多集中在0.4以下,占总数量的94%,其中0.3以下的占84.8%,0.1以下的占36.5%,且有超过1/3的试验落石几乎没有法向回弹,说明以前仅基于坡面软硬程度的法向恢复系数取值方法在实际工程中会使计算的落石弹跳高度偏大。从坡面铺装和坡度两方面综合考虑,给出了法向恢复系数取值建议表,并建议坡面越硬、坡度越大时取区间内高值,反之则取区间低值。
The value of normal restitution coefficient is the key parameter for calculating rockfall trajecto- ries. With high speed camera, the process of rockfall collision on slope was taken under various test condi- tions, namely, different slope pavement, gradient, falling height, rockfall mass and shape. The motion parameters before and after the rockfall collision on slope were obtained. Accordingly, the normal restitu- tion coefficients were worked out by inverse calculation. The conclusions are drawn as follows. The slope pavement and gradient are the key factors for normal restitution coefficient, while the shape, mass and falling height of rockfall have no obvious influence on normal restitution coefficient. As the slope pavement changes from hard to soft, the normal restitution coefficient decreases gradually. As the gradient increases, the normal restitution coefficient increases gradually. Most of the normal restitution coefficients obtained from the test data under various test conditions are below 0.4 and takes 94% of the total, among which, 84. 8% is below 0. 3, and 36. 5% is below 0. 1. More than one third of the rocMall tested almost has no normal springback during collision process, which indicates that the previous calculation method for normal restitution coefficient based only on the soft and hard degree of slope will make the calculated rock- fall bounce height too large in practical engineering. The suggested values of normal restitution coefficients are proposed by comprehensively considering slope pavement and gradient. It is suggested that high value should be adopted when the slope pavement is harder and the gradient is larger, vice versa, low value should be adopted.
出处
《中国铁道科学》
EI
CAS
CSCD
北大核心
2015年第4期13-19,共7页
China Railway Science
基金
国家自然科学基金资助项目(51108488)
重庆市高校青年骨干教师资助计划(渝教人[2011]65号)
重庆市博士后科研项目特别资助项目(渝xm201102002)
重庆市高校创新团队建设计划资助项目(KJTD201305)
关键词
落石
运动路径
被动防护设计
法向恢复系数
模型试验
Rockfall
Trajectory
Passive protection design
Normal restitution coefficient
Model test
