Method for objectively determining crack initiation strength of rock on basis of accumulated sound emission impact times

Abstract

The invention belongs to the field of rock performance tests and specifically relates to a method for objectively determining crack initiation strength of a rock based on accumulated sound emission impact times. The purpose is to accurately identify the crack initiation strength value. The method comprises the followings: preparing a cylindrical rock test piece, installing the rock test piece on a test sample table of a press machine, installing a sound emission sensor in the middle part of a rock sample, uniaxially loading the rock test piece, synchronizing the sound emission monitoring and the loading process, acquiring the data of axial stress and accumulated sound emission impact times in real time, acquiring a curve of the accumulated sound emission impact times changing along with the time, drawing a curve of the relation between the axial stress and the accumulated sound emission impact times, calculating the difference of the accumulated sound emission impact times according to the relation curve, and drawing a relation schema of the difference of the accumulated sound emission impact times and the axial stress, wherein the stress corresponding to the peak of the difference of the accumulated sound emission impact times is the crack initiation strength of the rock. The method eliminates the subjective judgment of a user, and guarantees the uniqueness of the solution.

Description

technical field [0001] The invention belongs to the field of rock performance testing, and in particular relates to a method for objectively determining rock crack initiation strength based on accumulated acoustic emission impact numbers. Background technique [0002] The mechanical failure process of rock is the process of initiation, expansion and penetration of internal micro-cracks. The damage and failure process under compression can be divided into several important stages: (1) crack closure; (2) elastic deformation; (3) crack initiation; (4) crack stable development; (5) crack penetration; (6) Unsteady fracture development; (7) Destruction; (8) Post-destruction stage. Among them, the stress level corresponding to the initial crack is called rock crack initiation strength. Crack initiation strength (σci) is one of the important characteristic stress values ​​of rock in the process of compression failure. Reasonable determination of this stress value is of great signi...

AI Technical Summary

Problems solved by technology

However, due to the high sensitivity of the acoustic emission monitoring signal to the mechanical response of the rock and the interference of background noise, the rock may also detect a strong acoustic emission signal during the pore-fissure compaction stage and the elastic deformation stage, thereby interfering with the crack initiation. Accurate identification of intensity values

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