泥石流防撞墩冲击力理论计算方法

Theoretical Method for Calculating Impact Force on Debris Flow Protection Piers

在西部泥石流多发区,交通线路经常需要穿越泥石流沟,设置在泥石流沟床中的桥墩容易遭受泥石流大块石的冲击,为此,常常在其前端设置泥石流防撞墩,以达到保护桥墩的目的。防撞墩设计的关键参数是泥石流大块石的冲击力。目前,有关泥石流冲击力的计算方法都比较粗糙,计算结果与实际情况不符。本文以Thornton理想弹塑性接触模型为基础,并考虑防撞墩的弯矩变形特性,根据能量守恒定律,推导了泥石流大块石冲击力的计算公式。结果表明,考虑结构弹塑性特性后,泥石流大块石冲击力大大降低,远小于按弹性冲击理论所确定的冲击力,计算结果更符合实际情况。

In the western regions of china where debris flows occul frequently, the traffic routes always need to go through the debris flow channel, so the piers built in the channels of the debris flow are easily suffered the impact of the big block rock in debris flow. Therefore, the designer generally set up the debris flow protection frustum in front of the piers to protect them. The key parameter of the design of the protection pier is the impact pressure of the big block rock in debris flow. At present, all the methods of calculating the impact pressure are relatively rough and their results are inconsistent with the actual situation. In this paper, on the basis of the Thornton＇s elastic-plastic contact model and considering the deformation properties of the protection frusta and basing on the conversation of energy, the impact pressure calculating formula of the big block rock in debris flow is derived. The results have shown that by considering the structure＇s elastic-plastic properties, the actual impact pressure caused by big block rock reduces greatly and far less than the nominal elasticity impact pressure. This result agrees better than others with the actual situation more.