低应变反射波法检测缺陷桩的难点技术研究

通过多年的桩基检测实践,对低应变反射波法检测桩基的几个难点技术进行了深入研究。以一维弹性杆波动理论为基础,建立了基桩缺陷与反射波波形的关系,并对具有同样的同相反射或反相反射的缺陷以工程实测波形为例,从波形特征上阐明了缩径与离析、夹泥与空洞、局部断裂与断桩的区别,论述了桩顶浮浆层对波形曲线的影响、大直径桩的横向惯性效应以及不同桩型、不同桩底持力层的桩底反射波特征。从而能较好地避免缺陷的误判,对反射波法检测桩基完整性具有较大的借鉴意义。

Study on inspecting technique for defective piles with low strain dynamic tests

Some testing techniques for defective piles are studied with low strain dynamic tests based on the pile inspecting practice for many years. According to the wave theory with one-dimensional elastic rod, the relationship between the wave characteristics and the pile defects have been developed. Taking the actual engineering waves as the examples, the characteristics of reflection waves for different pile defects have been discussed. The influence of the laitance on the wave curves and the transverse inertia effects of larger diameter piles and the reflection wave characteristics at the pile bottom of different piles have been explained, which could effectively avoid the miscarriage of the judgment for pile defects and has the directive significance to the integrality inspection of piles by using low strain integrity testing method.