Developing a New Bursting Liability Index Based on Energy Evolution for Coal under Different Loading Rates

Naseer Muhammad Khan,Sajjad Hussain,Kewang Cao,Maqsood Ahmad,Faheem Ur Rehman,Hafeezur Rehman,Imtiaz Ali,Wei Liu,Tufail Ahmed

doi:10.3390/su14031572

Abstract

The risk of a coal burst rises with the excavation depth and other mining-related activities. These devastating coal burst activities are a major concern during deep coal mining. During such activities, the loading rate is a major cause of damage. Different indexes, including the elastic strain modulus index (Wet), bursting energy index (Ke), dynamic failure time index (DT), and compressive strength index (Rc), are used for coal bursting intensity; however, the loading rate and damage factors are not included in these indexes. In this study, a new coal bursting liability index called the elastic modulus damage index (EMDI) was developed using rock damage variables and the elastic strain modulus index, and is based on energy evolution characteristics under different loading rates. The results of this new index were compared with the existing indexes, and their range was proposed to evaluate coal bursting liability. The EDMI shows a positive polynomial second order degree relationship with Wet and Ke, having a determination factor of 0.99, while DT shows a negative polynomial second order degree relationship with a determination factor of 0.94. The EDMI and Rc show a positive power relationship having a determination factor of 0.99. The relationships with other indexes revealed that the EDMI can be effectively used in evaluating the coal bursting liabilities in different stress environments.

Highlights

China is one of the leading countries globally both in the production and consumption of coal
The coal specimens during loading showed that some mechanical properties increased, and some decreased with the loading rate
The residual strength increased with loading rate, i.e., at loading rates 0.1, 0.4, 0.7 and 1 mm/min, the corresponding residual strengths were 1.80, 1.99, 2.24 and 2.50 MPa, respectively (Figure 4b)

Summary

Introduction

China is one of the leading countries globally both in the production and consumption of coal. 3.41 and 2.70 billion tons of coal, respectively [1,2,3] To fulfil this demand, mining has been switched to deep underground excavations in the country due to the depletion of shallow reserves [4,5,6,7,8]. Sustainability 2022, 14, 1572 coal burst type hazards are a major issue that threatens production and economic losses and leads to injuries and even casualties [5,9,10,11,12,13].

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Discussion

Conclusion