前言 随着高层建筑的迅猛发展,桩基工程得到了普遍的应用。在桩基工程中,往往由于工程地质及施工技术等方面的原因,桩身很容易出现离析、缩颈、断裂、夹泥等缺陷,加之桩基属于隐蔽工程,不容易发现这些异常。为了保证工程质量,1995年元月我站引进中科院武汉岩土力学研究所生产的 RSM- 24FD工程动测仪,四年来已成功地在陕西汉中市政府住宅楼、汉中市区电力调度大楼、汉中供电局调度大楼等高层建筑中应用,取得了较好的质量控制效果、本文就应力反射波法检测桩基的原理以及结合陕南的实例对波形判断、缺陷的性质。程度、位置等问题进行分析探讨。 低应变反射波法诊断原理 桩完整性的低应变检测是在桩头激发应力脉冲（锤击）,用置于桩头的速度传感器（或加速度传感器）接收反射波信号,根据反射波的相位、到时,对桩身质量作出定性的分析判断。它的理论是以一维弹性杆平面应力理论为基础的。由波动理论可知,桩身波阻抗（Z）是截面面积（A）、材料密度（P）、波速（c）和弹性模量（E）的函数: 将一继波动理论用于线弹性桩（桩长≥直径、入射波长>桩直径）,在桩顶锤击力作用下,产生一压缩液,此波 Foreword With the rapid development of high-rise buildings, pile foundation engineering has been widely used. In the pile foundation project, due to the engineering geology and construction technology, the pile body is prone to segregation, necking, fracture, mud and other defects. In addition, the pile foundation is a hidden project and it is not easy to find these anomalies. In order to guarantee the quality of the project, in January 1995, I station introduced the RSM-24FD engineering tester manufactured by the Wuhan Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. In the past four years, it has successfully completed the construction of Hanzhong City Government Housing Building, Hanzhong Urban Power Dispatching Building, and Hanzhong. The application of high-rise buildings such as the dispatching building of the power supply bureau has achieved good quality control results. The principle of the stress reflection wave method for the detection of pile foundations and the combination of examples in Southern Shaanxi are used to determine the waveform and the nature of defects. The degree, location and other issues are analyzed and discussed. Low-strain reflected wave method diagnostic principle Low-strain detection of pile integrity is to stimulate the stress pulse (hammer) at the pile head and receive the reflected wave signal with a speed sensor (or acceleration sensor) placed on the pile head, according to the phase of the reflected wave, At that time, qualitative analysis and judgment were made on the quality of the pile body. Its theory is based on the one-dimensional elastic rod plane stress theory. From the wave theory, the wave impedance (Z) of the pile body is a function of the cross-sectional area (A), the material density (P), the wave velocity (c), and the elastic modulus (E): A continuous wave theory is used for linear elastic piles ( Pile length ≥ diameter, incident wavelength> diameter of pile), under the action of hammer force at the top of the pile, produce a compressed liquid, this wave