Coal-like rock ground stress K-point test method based on Kaiser effect

Abstract

The invention discloses a coal-like rock ground stress K-point test method based on a Kaiser effect. A coal-like test piece is replaced with an undisturbed low-strength concrete test piece to reduce the influence of the original occurrence stress. Two resonant frequency sensors are used to simultaneously collect acoustic emission signals. Two representative acoustic emission time domain parametersare used to determine a Kaiser effect point comprehensively and preliminarily; at the same time, the accuracy of the main frequency is tested according to distribution characteristics of the main frequency; finally, verification is carried out again from a multi-band energy distribution characteristics aspect; and three methods are established to prove each other and improve the test accuracy.

Description

technical field [0001] The invention relates to the field of in-situ stress testing, in particular to a method for testing the K-point in-situ stress of coal-like rocks based on the acoustic emission Kaiser effect. Background technique [0002] At present, the ground stress test methods include hydraulic fracturing method, stress relief method, strain recovery method, drilling caving method, acoustic emission Kaiser effect method, etc. Among them, the acoustic emission Kaiser effect method has the advantages of simplicity, intuition, and easy mass testing, and can Realize the fine test of ground stress. The key to Kaiser effect measurement of ground stress is the selection of K point. The selection method is continuously innovated on the original parameter selection method. At the same time, a lot of research on its effectiveness has been carried out, and certain results have been obtained. [0003] It is not yet clear whether the stress suffered by coal during its occurren...

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Problems solved by technology

[0004] At present, most of the achievements mainly use a single resonant frequency sensor to collect acoustic emission signals in the whole process of destroying the rocks existing in the earth’s crust. When determining the K point, a single parameter is often used for analysis. Due to the differences in the signals collected by various resonant frequency sensors, And the differences in the distribution characteristics of each parameter of acoustic emission lead to the diversity of research results, which brings difficulties to the application of acoustic emission Kaiser effect to test the ground stress

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