Mechanism and Inducing Factors of Rockburst Events of Roadways Under Ultrathick Strata

Zhen Hao,Guangzhong Sun,Guohua Zhang

doi:10.3389/feart.2022.860929

Abstract

The overlying strata of the Yima coalfield are ultrathick conglomerate. Aiming at the problem of frequent occurrence of rockburst events in the central Yima coalfield during 2006–2015, the characteristics of rockburst events, microseismic (MS) monitoring, and rockburst event-inducing factors were analyzed through data mining and field investigation methods. The results showed that the rockburst events in roadways mainly occurred during mining of the working face, and they occurred at a large buried depth and were within the influence of mining stress, accompanied by an abrupt energy release. The occurrence of rockburst in roadways was accompanied by a sudden release of energy. The ultrathick strata and the fault nearby were the key influence factors of rockburst events. The stress field of roadway surrounding rocks was changed because of the mining disturbance, roadway repair and maintenance, and blasting, which would change the regional stress fields in the surrounding rocks and induce roadway rockburst events. The characteristics of rockburst events were floor heave, sharp convergence of two side walls, severe damage of the supporting body, and even closure of the roadway. The occurrence of rockburst can be prevented by reducing the mining speed and injecting water into coal seam.

Highlights

Rockburst is an instantaneous release of elastic energy of an over-stressed coal and rock mass and has been recognized as one of the most critical dynamic failures in coal mines (Dai et al, 2021; Frith et al, 2020; Keneti and Sainsbury, 2018)
As displayed in the figure, roadways at burial depths of 600~700 m and deeper than 700 m were separately subjected to 46 and 44 rockburst events, which accounted for 42.6% and 40.7% of the total
Because the working face was in the initial mining stage, the analysis indicates that the rockburst event was induced by factors related to the mining activities

Summary

Introduction

Rockburst is an instantaneous release of elastic energy of an over-stressed coal and rock mass and has been recognized as one of the most critical dynamic failures in coal mines (Dai et al, 2021; Frith et al, 2020; Keneti and Sainsbury, 2018). The disaster poses a serious threat to the safe production of underground coal mining. It can destroy roadways with hundreds of meters instantaneously, causing injuries or deaths, damage to facilities, and leading to property losses. Complex and various geological conditions during tunneling and mining in coal mines lead to different causes and failure modes of rockbursts (Jiang et al, 2019; Wang et al, 2019). Coal mine safety production in many countries is seriously threatened by rockburst disaster, especially in countries such as South Africa, the United States, Russia, Australia, Czechia, Poland, and China (Ghorbani et al, 2020; Konicek et al, 2013; Małkowski and Niedbalski, 2020; Zhang et al, 2017). Rockburst disasters have become a major problem in deep mining (Anderson, 2017; Ranjith et al, 2017)

Objectives

Methods

Findings

Discussion

Conclusion