PCC桩低应变检测中的三维效应

Three-dimensional effects in low strain integrity test of PCC pile

分析了低应变检测对PCC大直径薄壁混凝土管桩的适用性。对低应变中受瞬间冲击荷载作用的完整和缺陷PCC桩的动力响应进行了一维及三维有限元模拟,详细研究了PCC桩低应变检测中的三维效应。研究结果表明:除了一维应力波理论中的纵向振动外,PCC桩顶所测的动力响应中还包含弯曲振动以及波在桩顶表面传播和内外边界上的反射的影响。在研究结果的基础上,对PCC桩低应变检测试验中激振点和测点的最佳位置和如何合理分析试验结果给出了建议。

The objective of this paper is to present a theoretical evaluation of the capabilities of low strain integrity tests in estimating the pile length and integrity of PCC pile, a type of large diameter thin-wall cast-in-place concrete pile. One-dimensional and three-dimensional finite element modelling are performed to gain an understanding of the dynamic response of intact and defective PCC pile subjected to impulse loads. The three-dimensional effects in low strain integrity test of PCC pile are studied in detail. The result shows that the impact response of a PCC pile is affected by bending vibration, longitudinal vibration and waves reflected between the side boundaries at the surface of pile top. Based on the numerical results, suggested guidelines for selection of the locations of the hammer impact point and the recording point and test results interpretation of this new type of pile are given.