A method for measuring loose circles of surrounding rocks based on distributed resistance strain gauges

Abstract

The invention provides a method for measuring loose circles of surrounding rocks based on distributed resistance strain gauges. The method comprises the steps of: making and processing a test element and numbering resistance strain gauges on the surface of a PVC pipe body; performing construction drilling, placing the test element in the drilled hole and performing grouting and hole sealing to make the test element and surrounding rocks effectively coupled; measuring the surrounding rock strain value reflected by each resistance strain gauge successively by using a strain meter, drawing a relation curve of different surrounding rock positions and the strain values and obtaining the result that the surrounding rocks between the strain peak position to the drilling position are in the loose circle range through analysis. Compared with the prior art, the method has the advantages that the distribution range of loose circles is analyzed by using the resistance strain gauges to measuring the strain of coal-rock bodies at different positions. The operation is convenient, rapid and economical, the sensitivity is high, the data processing for the measuring results is easy, and the method facilitates field implementation.

Description

technical field [0001] The invention belongs to the technical field of mine pressure testing, and relates to a method for measuring loose circles of surrounding rocks based on distributed resistance strain gauges. Background technique [0002] After the roadway is excavated, the stress balance state of the original rock is destroyed, resulting in stress redistribution, accompanied by the appearance of stress concentration. When the concentrated stress is greater than the strength of the surrounding rock, different levels of rock damage occur in the surrounding rock and gradually expand from the periphery to the depth, forming a loose circle composed of damaged and broken rock mass. The physical state of the loose circle is manifested by the increase of cracks and the decrease of the stress level of the rock mass. Its size reflects the result of the combined effect of factors such as surrounding rock stress and rock strength. It is an important parameter for analyzing the sta...

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Problems solved by technology

[0004] The geological radar detection method is a new type of non-destructive detection technology, which can adapt to surrounding rocks of different strength levels, and has high accuracy, efficiency, and resolution. However, this method is expensive, the test method is complicated, and there are many environmental interference factors; The testing principle of the seismic wave method is to directly use the arrival time fitting curve of the total wave to compare and judge the rock formation velocity. The test range is large and the data is reliable, but the instruments used are expensive, and the probe layout and instrument installation are difficult; the penetration method test The principle of the method is simple, and the permeability becomes larger when there are many cracks in the rock mass and develops, but for soft rock and water-swelling rock formation, the test is difficult and the workload is large; the sonic method needs water injection coupling during the test, and the anti-interference ability Poor, when the surrounding rock is damaged and the wave velocity of the cracked rock mass is not much different from that of water, the scope of the loose circle cannot be clearly judged; the principle of the multi-point displacement measurement method is due to the generation and development of cracks in the loose circle The deformation is larger than that of the unloose surrounding rock at depth. The advantages of this method are that the test data is reliable and the operation is simple, but the workload of observation is large, the accuracy of the test is low, and the monitoring time is long. For the surrounding rock with small deformation, It is difficult to observe; the borehole camera method is suitable for rock mass with good lithology, and the amount of information obtained is large, and the test result is high in accuracy, but the instrument is expensive and the on-site operation is complicated

[0005] In the specific construction process at the site, most of the above methods to measure the surrounding rock loose circle have the problems of complicated operation, high test cost and heavy workload

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