Research On Portable Intelligent Detection System For Bolt Anchorage Quality

Bolt support is widely used in mining and geotechnical engineering.It has the characteristics of good support effect and fast construction.It is an important support method to provide key support force for roadway and tunnel and maintain the stability of surrounding rock mass.However,in the actual support engineering,there are problems such as non-standard construction and inadequate monitoring measures,which lead to substandard support quality,roof falling,collapse and other accidents,resulting in a large number of property losses and casualties.Therefore,it is of great significance to study and design an intelligent system which can detect bolt anchoring quality quickly and accurately.Based on the principle of ultrasonic guided wave,a portable intelligent detection system for bolt anchorage quality was designed in this paper.The effectiveness of the system was verified by theoretical analysis,software and hardware development and experimental research.The main work of this paper are as follows:(1)The transmission characteristics of ultrasonic signal and attenuation of guided wave in bolt anchoring system were analyzed.The group velocity and phase velocity in the process of ultrasonic guided wave propagation were compared and the energy propagation velocity of wave group was studied.Through the analysis of the dispersion mechanism of ultrasonic guided wave signal transmission,it was determined that the ultrasonic guided wave with low-frequency longitudinal mode was selected to study the detection system of anchor length and anchorage quality.(2)The identification algorithm model of echo signal crest of bolt anchoring quality detection based on ultrasonic guided wave method was established.In the actual data,the peak position is fuzzy and there are many weak peaks and false peaks,which leads to a large deviation between the read peak point and the real peak point.In this paper,a wave peak recognition algorithm of ultrasonic echo signal was proposed,which can effectively suppress the detection environment noise interference and has a good recognition effect.(3)The implementation scheme of bolt length and anchorage quality detection system based on ultrasonic guided wave method was established,and the prototype of bolt anchorage quality intelligent detection system was studied and developed.The detection system mainly includes hardware and software.The hardware part took resonant acoustic emission sensor and microprocessor as the core,including signal isolation and driving,signal conditioning and other circuits;In the software part,the programs of signal excitation and acquisition,echo signal noise suppression and crest identification,spectrum analysis and multi curve parameter display,as well as the host computer management system were designed.(4)The simulation experiment model of bolt anchorage matching with the field working conditions was built,and the simulation experiment was tested and studied.A variety of bolt anchoring experimental models under multiple working conditions were built by using bolt,anchoring agent and concrete grouting solid body.Simulation tests were carried out respectively,and the experimental data under various typical working conditions were obtained.After research and analysis,the preliminary results show that the detection error is better than 5%.There are 55 figures,4 tables and 82 references.