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Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave

A work load, non-destructive testing technology, applied in the direction of measuring force, measuring device, instrument, etc., to achieve the effect of strong operability, high detection accuracy, and easy real-time monitoring

Inactive Publication Date: 2010-05-12
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of effectively measuring the working load of the anchor bolt, and propose a method for non-destructive testing of the working load of the anchor using low-frequency guided waves

Method used

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  • Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave
  • Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave
  • Method for performing non-destructive detection on service load of anchor bolt by using low-frequency guided wave

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Experimental program
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Effect test

Embodiment 1

[0042] Using a guided wave with a frequency of 50kHz to detect a free bolt, the measured V f =5010.4m / s, according to step 3, the frequency of 50kHz guided wave is measured at the propagation time t=3.992e-4s of the free section of the end anchor and bolt without working load, and then the length of the free section of the end anchor and bolt is determined L= 1m. Apply a preloading force F'=40kN to the anchorage bolt to be tested, and the propagation time Δt of the guided wave at the free section of the anchorage bolt at the end of the preloading force AB '=3.995e-4s, then the propagation velocity V of the guided wave at the free section of the anchor bolt at the end of the pretightening force is obtained by step 4 f F '=5008.8m / s. Measure the time Δt of the guided wave propagating in the free section of the anchor bolt under the action of the working load F AB =4.001e-4, the working load F=100.628kN is calculated from step five, and the actual value of the working load is ...

Embodiment 2

[0044] Using a guided wave with a frequency of 60kHz to detect a free bolt, the measured V f =4936m / s, according to step 3, the propagation time t=4.051e-4s of the guided wave with a frequency of 60kHz in the free section of the end anchor bolt without working load is determined, and then the length of the free section of the end anchor bolt L=1m is determined . Apply a preloading force F'=40kN to the anchorage bolt to be tested, and the propagation time Δt of the guided wave at the free section of the anchorage bolt at the end of the preloading force AB '=4.055e-4s, then the propagation velocity V of the guided wave at the free section of the anchor bolt at the end of the pretightening force is obtained by step 4 f F ′=4934.4m / s. Measure the time Δt of the guided wave propagating in the free section of the anchor bolt under the action of the working load F AB=4.0615e-4s, the working load F=102.2kN is obtained from step 5, and the actual value of the working load is 100kN, ...

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Abstract

The invention relates to a method for performing non-destructive detection on a service load of an anchor bolt by using low-frequency guided wave, which can detect the change of the service load of the anchor bolt on the spot, and belongs to the field of non-destructive detection. The method comprises the steps of: firstly, determining the propagation velocity of the guided wave in the free anchor bolt and the length of a free segment of the end anchor bolt; then determining the propagation velocity of the guided wave in the free segment of the end anchor bolt acted by a pre-tightening force; and finally, establishing a relation curve of the service load and the propagation time of the guided wave in the free segment of the end anchor bolt. On this basis, the service load can be determined by detecting a reflection echo of the guided wave on an upper interface of the anchoring segment of the end anchor bolt and the propagation time of the guided wave in the free segment. The method can detect the service load of the anchor bolt, can improve confidence level, and has the advantages of simplicity, strong operability and easy real-time monitoring.

Description

technical field [0001] The invention relates to a method for non-destructive detection of the working load of a bolt by using guided waves, which can detect the working load of the anchored bolt on site, and belongs to the field of non-destructive detection. Background technique [0002] With the development of the mining industry, the stability of underground structures has increasingly attracted people's attention. The research on the stability detection of roadway surrounding rock has developed to a new stage, and there are many mature technologies, such as roadway surface convergence displacement , deep base point displacement measurement, surrounding rock loose circle theory and detection, these technologies have been widely used in the stability control of coal mine roadway surrounding rock. However, these studies on the stability of the surrounding rock of the roadway structure all use the statics in solid mechanics as the main method, and the deformation of the surro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01L1/25
Inventor 王成何文宁建国唐永刚
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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