基桩超声检测有限元数值模拟研究

Finite Element Numerical Simulation of Pile Foundation Based on Ultrasonic Testing

超声无损法是对基桩完整性检测最主流的无损检测方法,与其他无损检测方法相比,超声无损检测对基桩的检测完全,结果直观,不受基桩长度、直径和周围环境限制。对于基桩的完整性检测,传统超声检测方法可能存在对声学缺陷信息的误判和漏判。为了更准确地判断基桩完整性的声学影响因素,通过COMSOL Multiphysics建立三维基桩的完整和典型缺陷模型,通过模拟声速和理论声速,比较验证COMSOL模拟声波在基桩中传播的可靠性。建立采集点位置不变缺陷位置逐渐变化的基桩空洞缺陷三维模型,通过对比声时信号和声波幅值,提出声波信号缺陷位置变化规律。建立水平间隙基桩模型,对比大小不同的有水平缺陷的声学参数可知,水平间隙缺陷在正常情况下难以发现,因而提出改进方法以避免漏判。

Compared with other non-destructive testing methods,ultrasonic non-destructive testing is complete and intuitive,and is not limited by the length,diameter and surrounding environment of pile.In the integrity testing of pile foundation,the traditional ultrasonic testing method may have misjudgment and omission of acoustic defect information.In order to judge the acoustic influence factors of pile integrity more accurately,this paper establishes the integrity and typical defect model of three-dimensional foundation pile by COMSOL multiphysics,and verifies the reliability of COMSOL simulation sound wave propagation in the pile by comparing the simulated and theoretical sound velocity.A three-dimensional model of pile cavity defect is established,in which the position of the acquisition point is unchanged and the defect position changes gradually.By comparing the acoustic time signal and the acoustic amplitude,the change rule of the defect position of the acoustic signal is proposed.The model of horizontal gap pile is established,and the acoustic parameters of different sizes of horizontal defects are compared.The results show that the normal condition of horizontal gap defects is difficult to find,and an improved method is proposed to avoid missing judgment.