泥石流大块石对简支梁冲击力修正计算

在泥石流易发区,针对格栅坝支墩、桥墩这样的简支梁结构,确定大块石的冲击荷载尤为重要。基于Hertz弹性球接触理论,结合Thornton理想弹塑性体假设,考虑混凝土材料受大块石冲击荷载作用下的弹塑性特性,将泥石流大块石冲击简支梁结构的整个动力响应过程概化为:第一次碰撞—桩身弯曲变形—第二次碰撞—静止。以能量守恒为基础,将泥石流大块石冲击力分解为第一次碰撞产生的冲击力和第二次碰撞产生的冲击力,以初次碰撞的冲击力为最大冲击力,提出了冲击力修正计算公式。最后进行实例分析,计算结果表明:梁长越短,冲击压力增长越快,梁长越长,冲击压力增长越慢,且该公式计算值仅占基于Hertz弹性球接触理论结果值的20. 3%,更符合实际情况。

Correction Calculation of Large Stone Impact Force of Debris Flow Grille Dam

In the prone area of debris flow, it is very important to determine the impact load of massive stone for simply supported beam structures such as grid dam piers and bridge piers. To that end, based on Hertz elastic ball contact theory and Thornton assumption that the material can be simplified to an ideal elastoplastic body, the elastoplastic behavior of concrete subjected to rolling stone impact load is considered , the whole dynamic response process is generalized as: first collision, bending deformation of pile body, second impact and static. Based on the conservation of energy, the formula for calculating the impact force of debris flow massive stone on simply supported beam structure is derived. The results show that: Sthe shorter the beam length, the faster the impact pressure increases, the longer the beam length, the slower the impact pressure growth. and the calculation results of the formula only account for 20.3 percent of the maximum impact pressure calculated on the basis of Hertz elastic ball contact theory, which is more in line with the actual situation. It is expected to provide some reference basis for the design of debris flow prevention and control engineering.