现浇薄壁管桩在低应变瞬态集中荷载作用下的动力响应解析解

管桩低应变检测时,平截面假定并不满足,应力波的传播不能简单地用一维波动方程描述。对于薄壁的大直径管桩,桩顶各点的动力响应沿径向变化不大,因此,可以假定各物理量沿径向无变化而建立只含有变量z,θ,t的波动方程。采用分离变量法和常数变易法求得了该波动方程的解析解,并对一个算例进行了计算分析,探讨了桩顶的动力响应和平截面假定的影响深度问题,并把计算结果与一维波动理论以及三维有限元的结果进行了对比分析。

Analytical solution of dynamic response of cast-in-situ concrete thin-wall pipe piles under transient concentrated load with low strain

The plane-section assumption was not congruous in low strain dynamic tests on pipe piles,so the propagation of stress wave couldn’t be expressed by 1D wave equation.The difference of dynamic response of large diameter thin-wall pipe pile along the radial direction was neglectable,and the dynamic response was assumed to be the same along the radial direction,as a result,only variables z,θ and t were contained in the wave equation.The analytical solution of the wave equation was obtained by separation of variables and the method of variation of the parameters.A case history was analyzed to discuss the dynamic response at the top of pile and the influence of plane-section assumption on effective depth,and the results were also compared with the results of 1D wave theory and 3D FEM.