考虑弹塑性变形的泥石流大块石冲击力计算

以Hertz接触理论为基础,考虑结构的弹塑性特性,给出泥石流大块石冲击力的计算方法。采用Thornton假设,即材料为理想弹塑性体,对Hertz接触理论进行弹塑性修正,推导考虑材料塑性的接触压力计算公式。为模拟泥石流大块石对构筑物的冲击,将构筑物假设成静止不动的平面,将大块石简化为以某速度运动的质点,建立基于修正Hertz接触理论的计算模型。计算结果表明,泥石流大块石在很小的冲击速度(小于1m/s)下就可能导致混凝土材料冲击接触面上产生塑性变形。考虑结构弹塑性特性后,冲击压力计算结果小于弹性冲击压力,更符合实际情况。

CALCULATION OF IMPACT FORCE OF OUTRUNNER BLOCKS IN DEBRIS FLOW CONSIDERING ELASTOPLASTIC DEFORMATION

A theoretical method based on Hertz contact theory is presented for calculation of impact force of outrunner block in debris flow. Special attentions are given to the elastoplastic deformation of structures. Hertz contact theory is modified using perfectly elastoplastic Thornton hypothesis to consider the elastoplastic deformation of structures. In the simulation of the impact of outrunner blocks in debris flow and counter structures,the structure is simplified as a still plane and the block is simulated by a particle with a certain velocity. So the impact force can be expressed by a simple function. Based on the modified Hertz contact theory and the simplified simulation of impact,a new method is approved to calculate the impact force of outrunner blocks in debris flow on structures. Based on a limited parametric study,it is shown that the impact causes plastic deformation on concrete structures at a low velocity. The impact force considering the elastoplastic deformation of structures can be far less than the elastic result. This new method matches the practice better.