Characteristics and evolutions of gas dynamic disaster under igneous intrusions and its control technologies

Determination of sealing depth of in-seam boreholes for seam gas drainage based on drilling process of a drifter

“…The coal mine is characterized by extremely thick igneous rock covering over coal seams (Chen et al, 2014;Wang et al, 2014). The igneous rock is distributed as a sill in the middle and western part of the Haizi coal mine, with an average thickness of 120 m. As the igneous sill is considered to be an impermeable rock bed, the gas pressure and content of the underlying coal seams are quite high and 11 gas outburst accidents have occurred in the Haizi coal mine .…”

“…The igneous rock is distributed as a sill in the middle and western part of the Haizi coal mine, with an average thickness of 120 m. As the igneous sill is considered to be an impermeable rock bed, the gas pressure and content of the underlying coal seams are quite high and 11 gas outburst accidents have occurred in the Haizi coal mine . Therefore, stress relief and gas drainage must be carried out before and during mining (Wang et al, 2014).…”

“…where, k is the permeability, k 0 is the initial permeability (see Table 2), ϕ is the porosity and ϕ 0 is the initial porosity, which is 0.05 here according to the literature (Wang et al, 2014). If the grain of the coal is assumed to be incompressible, we obtain (Zhang et al, 2009):…”

Dynamic Mechanical Behavior of Dry and Water Saturated Igneous Rock with Acoustic Emission Monitoring

“…With the increasing mining depth of coal mines, intrusive igneous rock is usually found around roadways and in the overlying strata above mining stopes [5]. Influenced by the multiple human mining activities and the natural shock and vibrations of earthquake, the hard igneous rock would suddenly break, instantly releasing a tremendous amount of elastic strain energy, which will easily induce the occurrence of complex dynamic disasters, such as rock bursts, water inrush, and gas outbursts [6][7][8][9][10]. The dynamic disasters in coal mines caused by the intrusive igneous rock impact the safety and productivity of the coal mines.…”

Methane and coal exploitation strategy of highly outburst-prone coal seam configurations

“…Generally, a gas content greater than 8 m 3 /t or 9 m 3 /t is considered sufficient to initiate an outburst if other conditions are favorable (Beamish and Crosdale, 1998;Lama and Saghafi, 2002). To reduce gas content and eliminate outburst hazards, the main methods are gas pre-drainage by using vertical surface wells or underground boreholes and, if possible, by pre-working a protective seam in combination with pressure-relief methane drainage (Cheng and Yu, 2007;Cheng et al, 2003;Díaz Aguado and Gonz alez Nicieza, 2007;Flores, 1998;Hungerford et al, 2013;Hyman, 1987;Lama and Bodziony, 1998;Lunarzewski, 1998;Sang et al, 2010;Wang et al, 2014).…”