岩土中爆炸冲击荷载的落锤模拟试验研究

Physical Simulation of Explosion Impact Load in Geomaterials by Drop Hammers

为探究落锤冲击岩土的荷载特性以及寻求模拟爆炸荷载的实用方法,分析了岩土中的爆炸冲击荷载特征,基于能量原理推导了一维应变状态下砂土受到落锤冲击后,受冲击端应力和作用时间的表达式,并通过试验对受冲击端应力峰值和作用时间表达式进行验证。试验发现:荷载正压作用时间与冲击速度无关,增大落锤质量和等效垫层厚度可延长正压作用时间;荷载应力峰值与锤头质量和冲击速度正相关,与等效垫层厚度负相关,通过在撞击面加设橡胶垫层可有效减小应力峰值,延长作用时间。提出的已知荷载条件下落锤工况设计方法,可为爆炸荷载模拟提供参考。

In order to explore the load characteristics of geomaterials impacted by drop hammers and seek a practical method to physically simulate explosion loads,the characteristics of the explosion impact load in geomaterials are analyzed.Based on the energy principle,the expression of the stress at the impact end and the action time after the geomaterials impacted by the drop hammer under one-dimensional strain state is derived.The expression of the peak stress at the impact end and the action time is verified by experiments.The test results show that the positive pressure action time has nothing to do with the impact velocity,increasing the weight of the drop hammer and the thickness of the equivalent cushion can prolong the positive pressure action time,and the peak stress of the load is positively correlated with the weight of the hammer and the impact velocity,and negatively correlated with the thickness of the equivalent cushion.By adding rubber cushion on the impact surface,the peak stress can be effectively reduced and the action time can be increased.The proposed design method of drop hammers under known load conditions can provide important references for simulating explosion load.