Strength, Deformation, and Acoustic Emission Characteristics of Raw Coal and Briquette Coal Samples under a Triaxial Compression Experiment.

Han Meng,Yuzhong Yang,Liyun Wu

doi:10.1021/acsomega.1c03543

Abstract

Raw coal and briquette coal samples have similar deformation characteristics. Addition of binders added into briquette coal could change the coal property. To better capture the characteristics of briquette coal samples in comparison to raw coal samples, we performed triaxial compression tests on raw coal and briquette coal samples with 7% content of four different binders. The experiment results show that the MD group (7% rosin) briquette coal has strong similarities to raw coal samples in strength, deformation, and acoustic emission (AE) features. We find that although four different binders (water, cement, rosin, and coal tar) are added into the briquette coal samples, the failure characteristic has high consistence. Briquette coal samples always show plastic failure, but raw coal always shows brittle failure. The increase in raw and briquette coal samples’ peak strength is associated with an increase in the confining pressure constant. However, as the confining pressure constant increases, the raw and briquette coal samples’ residual strength gradually reaches close to the peak strength. After the peak strength is reached, briquette coal samples always show a stronger strain and the raw coal samples have a weaker strain characteristic. AE events have a peak value on compression and elastic stage of briquette coal samples. AE events do not show a positive correlation relationship with the material strength of the briquette coal samples. Our study highlights that briquette coal samples with 7% rosin have more similarity in strength, deformation, and AE characteristic with raw coal samples.

Highlights

China has the largest number of coal mines and is the biggest coal producer in the world
Our study aims to find one type of binder briquette coal samples that are similar to the raw coal samples under triaxial compression
Under the confining pressure below 20 MPa, the raw coal samples all showed an obvious drop in stress, and the raw coal sample MJ 2 showed a steep drop of stress and the brittle failure characteristic

Summary

Introduction

China has the largest number of coal mines and is the biggest coal producer in the world. Coal as a significant fossil energy source occupies a major position in China’s energy consumption structures. With the depletion of shallow resources, deep mining has become a common choice for the constant development of coal mines.[1,2] In the Pingdingshan mining area, most of the mines have reached the depth of 800 m below sea level. Under the conditions of deep mining, the ground stress, gas pressure, and ground temperature all show obvious increase in characteristics.[3,4] the deep mining conditions are extremely complicated. To realize safe and highly efficient mining in deep mines, a comprehensive research on the failure features of coal and rock masses is necessary

Methods

Results

Conclusion