基于冲量定理的滚石对构筑物冲击力计算方法

A CALCULATION METHOD BASED ON IMPULSE THEOREM TO DETERMINE IMPACT FORCE OF ROCKFALL ON STRUCTURE

滚石灾害在工程施工过程中对施工人员、设备和构筑物具有较大的威胁,因此研究滚石的运动特性及其冲击力显得非常重要。基于刚体运动学原理建立滚石运动特性的计算方法,通过与数值仿真结果对比来验证其合理性,同时滚石的运动参数作为计算其对构筑物冲击力的基础参数。在考虑滚石自转的基础上,基于冲量定理提出滚石冲击力的计算方法,并结合弹性力学理论解决计算中的撞击时间难以确定的问题。利用提出的方法对长河坝环境边坡的滚石运动特性及冲击力进行分析,计算结果表明:滚石运动过程最大弹跳高度可达25 m、最大平动速度和转动速度分别可达到57 m/s及350 rad/s,滚石运动受地形影响较大。结合运动参数分析结果和冲击力计算模型确定滚石对不同部位构筑物的冲击力数值,冲击力计算结果为构筑物位置的选择及灾害防治提供了一定的参考。

Rockfall hazard has a greater threat on the construction workers,equipment and structures during the engineering construction process,so that it's important to understanding the motion characteristics and the impact force of rockfall. Based on the kinematic principles of rigid material,a calculation method is presented to simulate the motion characteristics of rockfall. The reasonable of the presented method is validated by comparison analysis of theoretical values and numerical results,and the motion parameters of rockfall are used to compute its impact force on structures. On the basis of considering the self-rotation of rockfall,a computational method for determination of impact force is presented base on impulse theorem,and the difficult problem for determining of the impact time is solved by use of elastic mechanics. The presented method is adopted to determine the motion characteristic parameters and impact force of the rockfall hazard at the natural slope of Changheba Hydropower Station. Simulated results show that,during the movement process of rockfall,the maximum jumping height is 25 m,the maximum translational velocity and rotational speed are 57 m/s and 350 rad/s,respectively;and influenced by the terrain condition. Combined with the motion parameters of rockfall and theoretical model for impact force,the impact force of rockfall effect on structure at different locations are determined,the calculation results have a great reference value to the location selection of structures and the hazard mitigation and prevention of rockfall.