摘要
对于在役基桩,由于桩顶部非裸露自由,低应变反射波法往往无法识别桩底反射。采用适宜的激振-检波配置方式,结合小波变换优良的时频特性,辅以双信号法定位桩底反射,可以较大程度的减小干扰,达到识别桩底深度的目的。通过建立桩-土-梁三维有限元模型,分别对梁顶及桩侧激振,对信号小波变换后,研究了不同激振-检波配置方式对波形的影响。结果表明:桩侧斜向激振时,检波点宜在激振面的侧面,且激振与检波点距上部结构一定距离有利于减小上部结构的干扰;在梁顶激振时,检波点宜在桩侧与上部结构保持一定距离;对小波波形双信号法的运用可进一步提高确定桩底深度的精度。
It is difficult to perform regular sonic echo （SE） tests for existing piles due to their unexposed pile head conditions. Wavelet transformation （WT） has good time-frequency characteristics, and can greatly reduce interferences. Adopting a reasonable excitation-receiver configuration, wavelet transformation combined with the double signal （ DS ） method can be used to identify the pile tip depth. Here, a three-dimensional finite element model for a soil-pile/column- beam system was used to simulate the testing. The lateral surface of the pile and the top surface of the beam were struck, respectively and wavelet transformation was employed to deal with the simulated signals. The effects of different excitation- receiver configurations on the waveforms were then investigated. It was shown that when the lateral surface of the pile is struck with the inclination angle of 45~, it is better to place the receiver in the side surface of the piled column ; keeping both locations of excitation and receiver away from the superstructure is strongly recommended ; when the beam top surface is struck, the receiver should be placed on the lateral surface of the pile away from the beam bottom as far as possible; finally, the application of the double signal method for wavelet waveforms is helpful to improve the accuracy of pile tip depth.
出处
《振动与冲击》
EI
CSCD
北大核心
2013年第21期92-96,共5页
Journal of Vibration and Shock
基金
国家自然科学基金项目(51178267)
交通运输部西部交通科技项目(20113182231390)
关键词
反射波法
小波变换
在役基桩
双信号法
sonic echo test
wavelet transformation
existing piles
double signal method
