现浇薄壁管桩低应变动力检测适应性探讨

现浇薄壁管桩是一种大直径的管桩，在低应变检测时必然存在平截面假定不满足以及桩头三维效应的问题。无桩帽管桩低应变检测时由于激发了非轴对称的弯曲模态，并不是达到一定的深度平截面假定就会满足，各截面不同的点会受到不同程度的高频干扰，桩顶90°点受到了较小的高频干扰，低应变检测时激振点与传感器夹角为90°时更容易得到清晰的反射波信号。解析解和有限元解的结果均表明，带帽桩在桩帽的动力响应信号能看到明显的桩底反射和缺陷反射时距离桩心不同点上所感受的高频干扰的频率一样，速度振幅不同，距桩心0.50 （ 为桩半径）的点受到最小的干扰。

Study on applicability of low strain dynamic testing on cast-in-situ concrete thin-wall pipe pile

There are some problems such as plane-section assumption and three dimensional effects in dynamic testing on cast-in-situ concrete thin-wall pipe pile with large diameter. The plane-section assumption is not always satisfied in low strain dynamic testing of pipe pile without cap, because the nonaxisymmetric bending mode is excitated. The measuring point on top of pile at angle of ninety degree will suffer less high-frequency interference. So, the reflected wave signal is distinct and clear at this point. Both analytical and numerical results indicate that the reflection peak from pile bottom and defect is obvious at the top of pile with cap. The high-frequency interference at different points with different distance from the center of cap pile has the same frequency but different velocity amplitude. The point with distance 0.5k from the center of cap pile surfers minimum interference.