重锤低击和轻锤高击沉桩效果分析

Study on effects of sinking pile with heavy hammer and low drop distance or light hammer with high drop distance

为了分析锤击桩在沉桩过程中的力学机理,将人们停留在经验层面上的对沉桩过程、锤重选择的认识上升到理论高度。根据动能、动量守恒定律,用有限元法对能量从锤传递到桩这一过程的损耗情况和同等锤击能时锤的质量对桩身最大压应力分布、锤击持续时间、贯入度的影响等方面进行了分析。结果表明:锤的质量越大,能量损耗率越小;重锤低击会减小桩顶部的最大应力,增大桩身下部的最大压应力,明显延长冲击持续时间,显著增加贯入度。对锤击桩的施工有指导作用。

In order to analyze the mechanical mechanism of hammered pile in the process of pile sinking and improve the cognition of process of pile sinking and hammer weight selection theoretically,the laws of momentum conservation and kinetic energy conservation as well as the finite element method are used to analyze the energy loss and the influence of hammer quality with equal hammering energy on the maximum compressive stress distribution of pile,the hammering time and penetration degree.It is shown that the heavier the hammer is,the less the rate of energy loss is.The heavy hammer with low drop distance will reduce the maximum stress of pile top and the increase the maximum compressive stress of lower part of the pile.As a result,the hammering time is prolonged significantly and the penetration degree is increased obviously.