Study On Nondestructive Test Of Anchoring Quality Of Bolt Based On ICEEMDAN And Ultrasonic Guided Wave Method

Bolt anchorage support technology is widely used in geotechnical engineering such as slopes and deep foundation pits.Bolt failing will cause huge losses.Therefore,the detection of the anchoring quality of the bolt is particularly important.At present,there are few studies on the quantitative detection of the size of anchoring defect.The ultrasonic guided wave detection method has good sensitivity to the anchoring quality of the bolt.However,due to the dispersion and multi-modal characteristics of ultrasonic guided waves,it is difficult to analyze the detection signal,and the signal reflected from the defect interface is very complex,making it difficult to extract the characteristic signal of the defect interface.In order to solve the above problems,this thesis uses ultrasonic guided waves to detect the anchoring quality of anchoring defect anchors,and adopts the improved adaptive noise complete ensemble empirical mode decomposition(ICEEMDAN)method to analyze the ultrasonic guided wave detection signals in the anchoring bolts,and realize the quality inspection of bolt anchoring and the quantitative inspection of anchoring defect size.The main research contents and results are as follows:(1)Numerical models of bolts with different positions and numbers of anchoring defects were constructed using finite element software,and the law of ultrasonic guided wave velocity and attenuation characteristics varying with the position and number of defects was obtained.The results show that the position and number of anchoring defects will not affect the guided wave velocity.However,when the number of defects increases,the attenuation increases,which provides challenges to the detection of anchoring quality.(2)Using ICEEMDAN to analyze the bolt model with short exposed section,the hidden signal in the reflected signal is extracted,which verifies the analysis ability of this method.This method is used to deal with the numerical model data of anchoring defect bolts.The parameter analysis shows that the bolt length,anchor body length and defect position inferred based on the proposed method are in good agreement with the actual situation,and the calculation error of the single defect length is 3.3%,the calculation error of multiple defect lengths is within 10%.(3)An ultrasonic guided wave indoor testing platform for anchor bolts was built to carry out non-destructive testing of the indoor test samples of anchored defective bolts,and the ICEEMDAN method was used to process the reflected signals.The analysis results showed that the length of the anchor,the length of the anchor and the defect position is in good agreement with the actual situation.In particular,the calculation error of the length of a single defect is within 7.5%,and the best detection result is consistent with the defect length of the sample.The calculation error of the length of multiple defects is within 28%,and the minimum error is 7.5%.