特大型组合式高应变动力试桩重锤

Special large-scaled and knockdown hammer in high strain dynamic pile test

提出组合式重锤的概念,建立锤体受力模型及重锤-桩-岩土冲击响应问题的正演分析模型与算法;研究组合式重锤的适用性和安全性,以及高应变动力试桩中各桩土参数与试验结果影响关系。研究结果表明:锤体冲击过程中基本不受拉力,符合试验要求;特大型组合式基桩高应变动力试桩重锤应用于灌注桩承载力检测是可行的;锤重、落距、桩径、桩长、土阻力分布、桩侧及桩端土弹限、锤垫刚度和力脉冲宽度等因素对检测承载力均有较大影响。

Dynamic load testing requires enough impact energy to activate the specified test load or ultimate capacity. For drilling piles, the concept of knockdown hammer was presented, and the hammer force model and the hammer--pile-soil impulse response model with its arithmetic were described. The research of the utility and safety of the hammer was performed. The affecting factors of pile-soil system to the results of dynamic load testing were also analyzed. The results show that there is no tensile force in hammer during impact and it is feasible to utilize the hammer in drilling piles dynamic testing. Drop height, stiffness of cushion, pile length and diameter, and the soil qualities etc. affect the dynamic load testing results considerably.