基于小波变换的反射波法基桩检测  

Sonic echo test for pile integrity testing based on wavelet transform

作　　者：张敬一[1] 陈龙珠[1] 

机构地区：[1]上海交通大学船建学院安全与防灾工程研究所,上海200240

出　　处：《振动与冲击》2014年第6期179-183,共5页Journal of Vibration and Shock

基　　金：上海市科委资助项目(11dz1202000);国家自然科学基金项目(51178267)

摘　　要：鉴于反射波法在低应变检测中主要受较大长径比、桩侧土剪切模量及微小缺陷、桩顶非裸露自由等条件限制存在的局限性,而小波变换时频特性优良,适用于基桩检测信号中探测奇异成分,故通过建立三维轴对称有限元模型,对模拟信号进行小波变换后发现:对顶部裸露自由桩,小波变换可获取微小桩底或缺陷反射,可减小长径比、桩侧土剪切模量、缺陷面积的限制;通过平台激振,使平台在有效尺寸范围内实现对桩底的深度检测。The sonic echo test is a regular nondestructive test,and the applications are mainly limited in testing piles with high length-to-diameter ratio,high soil shear modulus,small defect areas or with an inaccessible head condition.Wavelet transform （WT）,however,has good time frequency characteristics,which is suitable for identifying the singularities of pile testing signals.Three-dimensional axial symmetric finite element models were used to simulate the testing,and the wavelet transform was employed to deal with the simulated signal data.It is found that for piles with accessible head condition,the wavelet transform can identify weak wave reflected from pile bottom or defects,then reduce the limitation of length-to-diameter ratio,soil shear modulus and defect areas.For pile with inaccessible head condition, the pile bottom can be identified by plate-excitation if the plate is within certain effective sizes.

关 键 词：反射波法 基桩 长径比 小波变换 桩顶非裸露 

分 类 号：TU473.161[建筑科学—结构工程]