Coal Seam Gas Migration Law In Layered Igneous Rock Erosion Area And Prevention Measures

Throughout history,always pushing economic development,energy demand in the energy industry structure optimization and upgrading of the form,the total coal production is still occupied more than 70% of the overall energy demand across the country,huge coal demand force increasing scope of coal mining,mining depth deepening constantly,lead to the influence of igneous rock erosion quantity increasing mine.Due to the hardness and compactness of igneous rock,the gas migration path in the mining process is limited,and a relatively closed separation zone is easily formed under igneous rock,and the gas accumulates in the separation zone,resulting in an increased risk of mine gas disaster.At the same time,igneous rock erosion of coal seam leads to significant changes in coal metamorphism degree and micro-pore structure,so the influence of igneous rock erosion on permeability coefficient of coal seam and effective influence radius of pre-drained coal seam should be considered when taking gas disaster prevention measures.On this basis,it is of great significance to develop the characteristics of gas migration law and coal quality of coal seam in the erosion area of layered igneous rock.Based on mechanical analysis,numerical simulation,laboratory testing and field test method for the coal to the analysis and research of the related parameters of igneous rock erosion,at the same time,starting from the engineering practice of Zou Zhuang coal mine7401 face put forward the corresponding gas disaster prevention and control measures and effect inspection,effectively prevent igneous rock erosion zone gas disasters and accidents.The main research contents of this paper are as follows:(1)When the coal seam presence of overlying layered igneous rock,with mining working face,the lower strata gradually sinking,and igneous rock affected by its physical properties,small displacement occurs,appears at the bottom of the igneous rock abscission zone,and because of the existence of igneous rock hindered the upward migration of gas,the gas gathered in the area of the abscission layer,therefore,simplifying the igneous rock for both ends clamped beam,The lower strata are masonry beams.By constructing the overall composite beam model,the change of stress field in the process of coal mining is analyzed and studied,and the formation process of separation layer and the characteristics of gas migration are summarized.(2)Using the Fluent software to gas concentration distribution in 7401 working face mining process to carry on the numerical simulation,and simulation of high pressure relief gas drilling area under different negative pressure gas concentration distribution,the results showed that high extraction can effectively reduce drilling delamination area gas concentration,and with the increase of extraction from negative pressure,the gas extraction effect is more obvious;(3)Through the laboratory measurement of coal moisture,volatile and ash content in igneous erosive and non-erosive areas,it is found that the roasting action of igneous rock on coal seam leads to the metamorphism of coal samples,and the internal structure is unstable,and the coal moisture decreases,and the volatile and ash content increases.It is found that the permeability coefficient of coal seam eroded by igneous rock and the effective influence radius of pre-drained coal seam are greater than that of non-eroded coal seam.(4)The gas disaster control measures of 7401 working face are designed,and the gas concentration changes of the upper corner,working face and return air lane are investigated through the monitoring system.The gas concentration of coal seam is controlled below the scope stipulated in The "Coal Mine Safety Regulations",and the safety of coal mine production is improved.