PHC管桩打桩过程中的动力响应分析

Analysis of Dynamic Response during PHC Pile Driving

为研究预应力管桩在打桩过程中的动力响应问题,结合应力波反射法基本原理,说明了应力波在不同类型基桩中的传播特性;再以预应力管桩施工工程为依托,对打桩过程中产生的冲击荷载进行简化,建立预应力管桩打桩数值模型,分析了2种特殊情况下桩基的竖向应力和变形。分析结果表明:当桩端固定时,固定端的竖向位移为0,而竖向应力幅值增加;当桩端自由时,自由端位移变化不大,而由于入射压力波与反射拉力波相互抵消,使得桩端竖向应力始终为0,而桩身竖向应力减小。数值模拟的结果与理论分析相吻合,同时也验证了建立数值模拟的合理性。通过对打桩过程中桩身的动力响应分析,不仅为管桩的设计和施工参数的选取提供了参考依据,而且对提高桩基声波检测的准确性具有重要意义。

In order to study the dynamic response of prestressed high-intensity concrete(PHC)during pile driving,the propagation characteristics of stress wave in different types of foundation piles are explained by the basic princi-ple of stress wave reflection method.Based on the PHC construction,the impact load generated during the piling is simplified,the numerical model of pile driving is established,and the vertical stress and deformation of pile foundation under two special conditions are analyzed.The analysis show that:when the pile end is fixed,the vertical displacement of the fixed end is 0,while the vertical stress amplitude increases;when the pile end is free,the displacement of the free end changes little,the vertical stress of the pile end is always 0 and the vertical stress of the pile body decreases because the incident pressure wave and the reflected tensile wave canceled each other.The results of numerical simulation are consistent with the theoretical analysis.The numerical simulation is rational.That the dy-namic response analysis of pile body during pile driving not only provide reference for the design of pipe pile and se-lection of construction parameters,but also improve the accuracy of pile foundation acoustic detection.