Stress Distribution Of Magmatic Evolution Tectonic Zone And Its Controlling Effect On Gas Dynamic Disaster In The Haizi Coalfield

Based on the combination method of theoretical analysis, field measurement and laboratory test, taking the Haizi coalfield which seriously eroded by igneous rocks as main research object, this paper studies stress distribution of magmatic evolution tectonic zone and its controlling effect on gas dynamic disaster, and puts forward the recommendations on optimal placement of borehole in accordance with thickness of overlying sills. The main conclusions as follows:1) The magmatic activity of Huaibei coalfield is obviously controlled by the geological structure, whose intrusion way is the deep magma source upwelled along the Tanlu fault, at the connection of the Tanlu fault and the Subei fault, some of the magma flowed into Su Bei fault, then invaded into the Huaibei coalfield. Combining the geological structure and the distribution characteristics of the sills of Haizi coal mine, it can be found that the Daliujia fault and the faults connecting with or deriving from Daliujia become the channels of magma intrudes into the coal seam. Afterwards, through the comparison and analysis of the roof and floor lithology and the marker bed, the magma intrusion ways of Haizi field are studied, by which to determine intrusion ways of the thick sills of Haizi field is mainly squeezing into the formation.2) With the increase of the thickness of the overlying sills, the geostress that the underlying formation suffers is bigger and bigger, the result of the actual measured geostress shows that the relationship of the ratio of the horizontal average stress and vertical gravity stress,av/h vs s and the thickness of the overlying sills H火is:,av/ 0.0071 0.7215 h vs s =H +火, then the actual measured amount of drilling cuttings of machine lane and the working face based on the different thickness of the overlying sills is added up, the result of which well verifies the conclusion.3) Through the laboratory test of physical parameters of 10 coal seam under different thickness of the overlying sills, it can be found that with the increase of the thickness of the overlying sills, the firmness coefficient of the coal samples gradually decrease, the micropore and small pore gradually develop, the utmost gas adsorption quantity and the initial speed of gas diffusion are gradually increasing, the capability of gas adsorption and desorption of coal is gradually enhanced. At the same time, according to the field measured data, the greater the thickness of the overlying sills, the larger of the gas pressure, gas content and gas emission quantity of the working face.4) According to the analysis of the coal and gas outburst accident of the Ⅱ1026 roadway and the gas overrun accident of the working face which has eliminated the outburst danger, the measures to optimize the intensive degree of the extraction drilling of the working face on the basis of the thickness of sills are put forward, that is the intensive drilling is designed in the area where is covered by bigger thickness of sills, while the relatively sparse drilling is designed in the zone where has smaller thickness of overlying sills.