Multi-frequency ultrasonic underground cavity scanning detection technology in borehole. (September 2020) - Wang, Jinchao
Highlights: Reasonable fusion of multi-frequency ultrasonic scanning data can improve detection accuracy and detection range. Underground cavity detection instrument by arranging horizontally and evenly multiple frequency transducers. A new ultrasonic technology of underground cavity scanning detection. Abstract: In order to solve the current situation that underground cavity contour detection is difficult, this paper proposes a multi-frequency ultrasonic cavity scanning detection technology in borehole. It is a scanning technology that uses a combination of multiple frequency ultrasonic probes to obtain more effective detection information and achieve the cavity contour accurate measurement, which provides an important reference for the underground cavity detection. Firstly, in view of the spatial arrangement of multiple ultrasonic transducers, the corresponding structural design scheme is proposed to realize the structural design of multi-frequency ultrasonic scanning system. Then, in order to better adapt to the detection requirements, through the simulation of ultrasonic sound field, the ultrasonic beam characteristics are analyzed. The frequency response factor concept of multi-frequency ultrasonic is proposed, and the weight distinction of different frequency acoustic signals and the evaluation of multi- frequency ultrasonic response weight are realized. Finally, combined with the actual detection environment, the influence of scanning time interval and scanning speed on the detection results is analyzed. The parameter matching relationship between mechanical scanning and space detection target is constructed, and the parameters of scanning detection system are determined. In addition, in order to verify the feasibility and accuracy of the technology proposed in this paper, based on the principle of multi-frequency ultrasonic detection and the design of scanning detection system, the corresponding multi-frequency ultrasonic scanning detection system is independently developed. The detection capability and reliability of the system are tested and analyzed by using the developed detection system. The error of the detection result is small, which verifies the feasibility and accuracy of the multi-frequency ultrasonic underground cavity scanning detection technology proposed in this paper.