基于小波分析的砂浆锚杆锚固质量缺陷评价

对深基坑支护中常用的岩土锚杆进行锚固质量无损检测的关键是对采集的动态加速度曲线进行合理的分析。为此,分别设计了三种不同工况模型:无缺陷、一个缺陷和两个缺陷的锚杆模型。通过敲击试验,采集到加速度响应曲线后,利用Matlab程序在计算机上实现波形重现,然后采用小波分析等方法对振动波形进行对比分析,建立振动波形与各工况之间的内在联系,以反映锚杆锚固质量的三个度量参数,亦即一次行波周期、时频谱中的频率值和能量衰减程度。结果发现:通过时域波形和时频谱可正确反映不同锚固状态下的动力响应规律,即锚固质量越好,锚杆中应力波衰减就越快。

ASSESSMENT OF ANCHORING QUALITY AND DEFECTS OF MORTAR BOLT BASED ON WAVELET ANALYSIS

It is a key for rock-soil anchor used in deep excavation support to assess anchoring quality by nondestructive testing method based on reasonable analysis of dynamic response curve of acceleration signal received by dynamic data recorder. So there different kinds of anchor models were designed for wholly grouted mortar bolts which had no defect,one defect,and two defects. Received the response curves of acceleration signals by tapping test,reappeared in computer by Matlab,then the vibration waveforms could be analyzed and contrasted by wavelet analysis,so the inner connexion between the vibration waveform and every model was established,which could reflected the three measure parameters,i. e. the period of a single cycle,the frequency value of time-frequency spectrum,and the deadening of energy. The results showed the rules of dynamic responses could be correctly reflected by the time domain waveforms and time-frequency spectrum for different anchor qualities. that were the faster of stress wave deadening in bolt,the better of anchor quality.