锚杆锚固缺陷无损检测信号的多尺度熵分析

Multiscale entropy analysis of non-destructive test signals of anchoring defects of rock bolts

煤矿巷道支护以锚杆支护为主要形式,锚固缺陷是影响锚杆支护质量的一个重要因素.为了提高声波法检测锚杆锚固缺陷的可靠性,利用自行设计制作的锚杆锚固质量无损检测实验系统对锚固系统无缺陷和含有若干缺陷的情况进行了检测.在使用经验模态分解方法对无损检测信号进行预处理的基础上,利用多尺度熵方法对重构的无损检测信号进行了深入分析,通过比较发现含缺陷锚固系统无损检测信号的多尺度熵值在绝大多数尺度上要比无缺陷锚固系统的大,说明含缺陷锚固系统无损检测信号的复杂度高.缺陷数目的增加导致各个尺度下的检测信号的多尺度熵值均增大,说明检测信号的复杂度和缺陷数目之间存在着明确的对应关系.研究结果揭示了锚杆锚固系统的内部结构特征影响检测信号复杂度的机制,为锚杆锚固质量的定量评价提供了一种有效的方法.

Bolt support is the main form of roadway support in coal mine, and anchoring defect is an important factor affecting the quality of bolt support. In order to improve the reliability of the acoustic method to detect the anchoring quality of the bolts, a non-destructive testing experimental system for the anchoring quality of the bolts designed and fabricated by ourselves was used to detect the situation that the anchoring system was defect-free and had some defects. Based on the pre-processing of the non-destructive testing signal by the empirical mode decomposition method, the multiscale entropy method was used to analyze the reconstructed signal. Through comparison, it is found that the multiscale entropy value of the non-destructive testing signal of the anchoring system with defects is larger than that of the defect-free anchoring system in most scales, indicating that the signal complexity of the non-destructive testing of the anchoring system with defects is high. The increase of the number of defects leads to the increase of the multiscale entropy values of the detection signal at all scales, which indicates that there is an explicit corresponding relationship between the complexity of the detection signal and the number of defects. The research results reveal the mechanism that the internal structure characteristics of anchoring system affect the complexity of detection signal, and provide an effective method for quantitative evaluation of anchoring quality.