管桩低应变检测中的三维效应分析

Analysis of 3 D Effects in Low Strain Testing of Pipe Pile

摘要:

建立了三维柱坐标下桩土系统瞬态振动的计算模型，根据弹性动力学方程、边界条件和初始条件，确立了定解问题.利用交错网格有限差分法编制了相应计算程序，得出该定解问题的数值解，探讨了完整桩在竖向激振力作用下的瞬态动力响应，给出了桩顶不同位置的速度时程灰度图，并比较了桩顶与桩底各点竖向速度时程曲线的差别.基于管桩的低应变完整性测试数据，验证了该数值算法的可靠性及其反映波在管桩中传播的三维效应的可行性.在实际检测过程中，特别是在三维波动方程无法求得解析解的条件下，该数值计算结果具有一定的指导意义.

Abstract:

A real three dimensional (3 D) pile soil model under cylindrical coordinate system is established in order to get a deep understanding of low strain integrity testing of pipe pile. According to elastodynamic equations, boundary conditions and initial conditions, the definite solution of this problem can be obtained. Then, based on the staggered grid finite difference method, the transient dynamic responses of a pipe pile subjected to transient vertical loading are discussed. Not only the velocities of different angles at pile top are obtained, but also the testing curves are presented, which directly reflects the 3 D effects of wave propagating in the pipe pile. Finally, the accuracy and feasibility of the numerical method are verified via comparing with the experimental data. In practice, especially under the conditions that the analytical solution of 3 D elastodynamic equations cannot be derived, the numerical solution has certain guiding significance.