A Study of the Laws of Abnormal Gas Emissions and the Stability Controls for Coal Mine Walls in Deeply Buried High‐Gas Coal Seams

Abstract

At the present time, it is considered to be of major significance to study the gas emission law and stability controls of coal bodies in deeply buried high-gas coal seams. For this reason, in view of the specific problems of gas emissions caused by unstable rib spalling in coal mine walls, comprehensive research methods were adopted in this study, in order to conduct an in-depth examination of micropore structure parameters, gas desorption, diffusion laws, and coal stability levels. The results showed that the development degree of the pores above the micropores, as well as the small pores in soft coal seams, was better than those observed in hard coal seams. In addition, the gas outburst phenomenon was found to have more easily formed in the soft coal seams. The coal body of the No. 6 coal seam in the Xieqiao Coal Mine not only provided the conditions for gas adsorption but also provided dominant channels for gas diffusion and migration. The abnormal gas emissions of the No. 6 coal seam were jointly caused by the relatively developed pores above the small holes in the coal body, rib spalling of coal mine walls, and so on. The research results also revealed the evolution law of mechanical characteristics of the No. 6 coal seam under different water content conditions. It was found that the strength levels of the No. 6 coal seam first increased and then decreased with the increase in water content, and the water content level at the maximum strength of the coal seam was determined to be 7.09%. This study put forward a method which combined the water injection technology of long-term static pressure water injections in deep coal mining holes and real-time dynamic pressure water injections in shallower holes. Field experiments were successfully carried out.

Effects of Microscopic Pore Structures on the Spontaneous Imbibition of Longmaxi Shale

“…The detailed experimental instruments and steps for HPMI, CRMI, LP-N 2 GA, imbibition, and NMR have been reported in our published studies (see refs , ). We note that HP-CH 4 GA was conducted with the 3H-2000PH full-auto high-pressure gas adsorption instrument at a pressure of 12 MPa and temperature of 50 °C. CH 4 with a relatively high purity (99.99%) was selected for adsorbate in the HP-CH 4 GA test (details about the test refer to ref ).…”

Study on Adsorption Characteristics of Deep Coking Coal Based on Molecular Simulation and Experiments

“…The development and utilization of coking coal plays a vital role in the development of China’s coal industry and is an indispensable resource for China’s economic construction . In recent years, with the increase in mining depth, the environmental conditions of high ground temperature and high gas pressure have appeared in the storage of coal. , Coking coal mines that originally belonged to the low-gas category have been upgraded to high-gas or even outburst mines. For a long time, the focus of gas control has mainly been on highly metamorphic coal represented by anthracite, and there are few studies on coking coal.…”

The Instability Characteristics and Displacement Law of Coal Wall Containing Joint Fissures in the Fully Mechanized Working Face with Great Mining Height

“…As an important part of the wall rock of the great mining height stope, the coal wall's stability has an important impact on the safe and efficient mining of FGH. The coal wall stability is mainly influenced by the strength of the coal body and the advanced abutment pressure of the working face [29,30], while the strength of the coal body and the abutment pressure within the limit equilibrium zone of the working face are related to the structural surfaces such as the joint fissures within the coal body [31,32], so the joint fissures within the coal body become a key factor affecting the coal wall stability [33][34][35][36][37][38][39][40][41][42][43][44]. Therefore, by systematically researching the influence of coal wall joint fissures on coal wall stability in FGH, physical and numerical simulation are used to analyze the instability characteristics and displacement law of the coal wall stability, and then find the rules and adopt appropriate methods to enhance the strength of coal bodies, so as to improve the coal wall stability, reduce the coal wall rib-spalling, and finally achieve high production and high efficiency in FGH.…”