Experimental Study on Acoustic Emission of Confined Compression of Crushed Gangue under Different Loading Rates: Disposal of Gangue Solid Waste

Laiwei Wu,Wei Li,Kun Ma,Yingshun Li,Junmeng Li,Shenyang Ouyang,Yanli Huang,Wen Zhai,Huadong Gao

doi:10.3390/su12093911

Abstract

The crushed gangue materials which are filled into the goaf in solid-backfilling coal mining become the main body of bearing the overburden after the tamping process. Its resistance to deformation is the key to control overburden movement and surface subsidence. Particle breakage affects the resistance to deformation of filling materials. In this paper, a confined compression test of crushed gangue under different loading rates was designed, and the acoustic emission (AE) signal was monitored in the process of confined compression. The test results showed that with the increase of loading rate, the anti-deformation ability of crushed gangue showed a dynamic change process of increasing, decreasing, and then increasing again. With the increase of loading rate, the breakage degree of the samples decreased, the proportion of large-sized gangue increased, the growth period of AE counts showed an obvious hysteresis phenomenon, and the AE activity level of the gangue increased gradually. The research results can not only provide a more in-depth and comprehensive understanding of the mechanical properties of crushed gangue filling materials but also provide a reference for the engineering application of solid-filling coal mining.

Highlights

Solid-backfilling mining can effectively control strata movement and surface subsidence and improve the “three-below” coal resources recovery rate
Cao et al [20] conducted an experimental study on the damage evolution rule and acoustic emission (AE) parameters characteristics of sandy mudstone under different loading rates and proposed a stress-strain constitutive model based on the rock damage
Seven groups of tests were designed to test the confined compression of gangue under seven different loading rates

Summary

Introduction

Solid-backfilling mining can effectively control strata movement and surface subsidence and improve the “three-below” (under the railway, under the water, under the structure) coal resources recovery rate. Xue [4] studied the mining dynamic response and failure mechanism of coal and rock under different loading modes and loading rates based on uniaxial tension and compression, conventional triaxial, and dynamic tests. Cao et al [11,12,13] studied the effect of loading rate on uniaxial compressive strength and acoustic emission characteristics of cemented tailings backfill. Li et al [16,17,18] studied the effect of loading rate on the mechanical behavior of the medium through uniaxial mechanical tests of coal at different loading rates. Cao et al [20] conducted an experimental study on the damage evolution rule and acoustic emission (AE) parameters characteristics of sandy mudstone under different loading rates and proposed a stress-strain constitutive model based on the rock damage. There are few studies on the effect of loading rate on the crushed-gangue fill materials used for backfill

Methods

Results

Conclusion