Mine ventilation provides fresh air to underground workers. The dampers can provide a qualified fresh air to each demand workplace by adjusting the air volume, which can ensure workers’ health. However, the powerful impact damage caused by gas explosions in the roadway can lead to deformation and damage to the dampers and even cause the breakdown of the ventilation system. At the same time, the impact effects of gas explosions may cause worker fatalities. For this reason, the dynamic response of gas explosions to dampers and their effects need to be studied. Based on the analysis of the damper construction and the damage characteristics of the gas explosion, ANSYS/LS-DYNA software is used to establish a mathematical-physical model of the damper with ventilation-regulating windows of six different sizes. The reliability of the model is verified by comparing the simulated pressure values with the values calculated by the Sadowski equation. The dynamic response characteristics of the dampers under the gas explosion impact are simulated and the displacement, equivalent stress and effective plastic strain of the dampers are measured. Finally, a theoretical analysis is carried out. The study results show that the displacement of the damper increases gradually from the edge to the center and the deformation is symmetrical in the absence of the ventilation-regulating window. The deformation region below the ventilation-regulating window is more obvious when the ventilation-regulating window is installed. The maximum stress of the damper first appears at the four corners of the damper, the stress of the unit at this position increases with the increase of the side length of the ventilation-regulating window. The stress of the unit in the lower left corner of the ventilation-regulating window first increases and then decreases with the increase of the side length of the ventilation-regulating window, and all the stresses of the units first increase and then decrease, and finally, the stresses basically approach a stable value. From the instantaneous ignition to the completion of the final reaction, the plastic strain gradually increases, but the area of the plastic strain region gradually decreases. The damage and deformation of the damper are basically consistent with the situation of the damper in the explosion accident. The research results can provide some theoretical basis and data support for the damper structure selection, damper location selection and setting of ventilation-regulating window.

Porous medium burners are characterized by high efficiency and good stability. In this study, a new burner was proposed based on the combustion mechanism of the methane-air mixture in the porous medium and the preheating effect. The new burner is a two-section and double-deck porous medium with gas inlets at both ends. A mathematical model for the gas mixture combustion in the porous medium was established. The combustion performance of the burner was simulated under different equivalence ratios and inlet velocities of premixed gas. The methane combustion degree, as well as the temperature and pressure distribution, was estimated. In addition, the concentrations of emissions of NO_x for different equivalence ratios were investigated. The results show that the new burner can not only realize sufficient combustion but also save energy. Furthermore, the emission concentration of NO_x is very low. This study provides new insights into the industrial development and application of porous medium combustion devices.

According to the existing problems of the control measures of uncovering coal seams in rock crosscut, such as long time of uncovering coal, poor construction safety, etc., the main effect factors of coal–gas outburst of uncovering coal seams in rock crosscut are analyzed, the existing hypotheses and the process of coal–gas outburst are described, and then the feasibility of the injection liquid freezing to prevent the coal–gas outburst is analyzed. It is concluded that the measure of the injection liquid freezing has the following functions: ① changing the physical properties of coal, ② improving the integrity of the surrounding rocks of the coal–rock interface, ③ enhancing coal strength, ④ effectively avoiding the discontinuous deformation of coal and rock under the action of gas pressure, ⑤ strengthening the block action of the external coal, ⑥ changing the stress distribution of coal near rock crosscut. The freezing makes the freezing ring in the roadway surroundings become a relatively stable flexible combination, which has a better stability. The experiment device of injection liquid freezing is designed, and the coal samples are analyzed before and after the freezing. The experiment results show that the indexes of coal–gas outburst are greatly dropped after adopting the measure of the injection liquid freezing, which can effectively control the coal–gas outburst. The experiments also show that it is feasible to prevent coal–gas outburst by the technology of the injection liquid freezing. The study results provide a new way to prevent the coal–gas outburst in uncovering coal seams in rock crosscut.

In order to obtain the damage characteristics of a roadway wall caused by a gas explosion, the damage evaluation theory of a roadway wall under the dynamic and static loads of a gas explosion is analyzed in this paper. Meanwhile, an evaluation method (overpressure–impulse criterion) is selected to evaluate the damage of the roadway wall under the impact load of the gas explosion. A mathematical model and a physical analysis model of the roadway wall damage are established by LS-DYNA software. The dynamic response of the roadway wall caused by the dynamic and static loads of the gas explosion is numerically simulated. The overpressure and impulse of gas explosion propagation are measured, while the damage data of the roadway wall under different overpressure and impulse loads are obtained. The P-I curves of the roadway wall under different dynamic and static loads of gas explosion are drawn. The fitting formula of P-I curves of the roadway wall is obtained. The influence of different geostress loads (0–20 MPa) on the P-I curve is analyzed. The shape of the P-I curve is similar under different geostress conditions. The difference is mainly shown in different sizes of P₀ and I₀. The numerical simulation results show that the P-I curve and the effect of geostress on roadway wall damage could reflect the dynamic response of the roadway wall. The damage degree and damage range of the roadway wall increase with the increase in explosion load energy. Under the action of different geostresses, the overpressure asymptote P₀ and the impulse asymptote I₀ show linear changes. The above research results could provide a theoretical basis and data support for the evaluation of roadway wall damage caused by gas explosions.