Movement laws of overlying strata and prevention measures of dynamic disasters under deep adjacent coal seam group with high gas

Abstract

The repeated mining of deep adjacent coal seam group with high gas has great influence on strata behaviours and dynamic disasters in underground mining. In this paper, the movement of overlying strata and gas for bi-level mining are studied, and then the effective methods of prevention and control disasters with consideration to the 'time-space-strength' is put forward. The results show that after the completely mining of upper coal seam and the lower coal seam been mining, the layers between coal seams move substantially and the tensile stress increases significantly, resulting in the overlying rock fissures are connected. Then, the stress of lower coal seam reaches peak value, and the dominant gas flow channel is formed, thereby causing in strong dynamic pressure phenomena such as increase in the gas pressure. After this, the self-developed gas sealing flexible air bag is used to block the gas in the position of face corner and to drain the gas in the goaf, which can effectively prevent gas outburst. The study results are of great significance and provide guidance to prevent dynamic disasters (i.e. gas outburst) caused by the repeated mining of adjacent coal seams.

Controlled reconstruction and application research of lateral overlying strata structure in high-gas mines with thick-hard roofs for a fully-mechanized top-caving face

“…Yang W [ 41 ] proposed injecting water into cracks formed by loose blasting to reduce the risk of gas outbursts. Zhang JG [ 42 ], Yuan AY [ 43 ] and Ye Q [ 44 ] found that fractures generated after mining could serve as gas flow channels and influence the direction of gas migration. He JF [ 45 ] conducted research on large-diameter boreholes and demonstrated their effectiveness in gas extraction from deep soft coal.…”

Mechanical behaviour and seepage characteristics of coal under the loading path of roadway excavation and coal mining

“…Under deep mining conditions, gas disasters such as coal and gas outburst, gas explosion, and gas suffocation are one of the most frequent and serious disasters (Yuan et al 2020). In order to prevent gas disasters, many scholars have conducted research on the formation mechanism and prevention methods of gas disasters, the disturbance effect of mining engineering, and the seepage characteristics of coal and rock (Gao, Zhang, Yin, et al 2018;Gao et al 2019;Ma et al 2020).…”

Experiment investigation on gas flow characteristics of coal considering the integrity of coal samples

“…The complex geological structure, high geo-stress, high gas pressure and low permeability of deep coal seam further increase the risk of gas disaster in coal mine (Xie et al 2012;Kong et al 2014;Gao et al 2019). At present, gas drainage is still the main method to reduce gas content and eliminate gas disasters (Xu et al 2006;Zhang et al 2018;Lu et al 2019;Yuan et al 2020), and the permeability of coal seam is the most important factor affecting gas drainage (Wang and Yang 2002;Gao et al 2020;Xie, Gao, Zhang, Liu, et al 2020).…”

“…At present, scholars mainly study the influence of coal structure on coal permeability from the distribution characteristics of coal cracks (Ma et al 2020;Yuan et al 2020). Fu et al (2009) used geophysical well testing to study the relationship between coal permeability and coal fracture characteristics.…”