| Based on the investigation of strata and the characteristic of tectonic and evolution in Xutuan coal mine,Tectonically deformed coal(TDC) samples of different deformation degree of coal No.32, 82 have been collected. Macroscopic, micro and super micro characteristics of pore structure and gas adsorption were deeply revealed based on hand specimen description, observation under microscope, mercury injection experiment and methane adsorption isotherm experiments. Comparision of borehole TDC types and characteristics of tectonic development, Xu Tuan ore TDC development pattern and tectonic control were analyzed, besides, combined with the coal seam gas content distribution,this paper explored the influence of Xu Tuan ore coal development law to gas occurrence.Tectonically deformed coal can be systematically divided into cataclastic structural coal, schistose structural coal, granulitic structural coal, scaly structural coal, wrinkle structural coal and mylonitic structural coal, 6 types, in which cataclastic structural of coal and schistose structural coal of weak brittle deformation are primary. Along with the change of the degree of deformation the law of characteristic of coal structure and gas properties produces significant changes. With the enhancement of deformation degree, coal native structure and bedding gradually disappear and the degree of fragmentation increase, from fragments, debris to broken power. Besides, fracture is gradually intensive, combination forms tend to be complex, the stability becomes weaker; micro pore and mineral clastic continue to increase, friction surface became more smooth, bright and coal body deformation from brittle to ductile transition; the overall of total pore volume, median pore size and porosity increase, while the local reduce, discrete enhancement; gas adsorption capacity by the fragmentation of coal, crushed coal to coal sheet increases slowly at first, followed by the scale of coal, crumpled to the significant increase in coal mylonite coal.Tectonically deformed coal are widely distributed throughout Xu Tuan coal mine, the central of the mining area is the most developed and the thickness is the largest and repeatedly occur. Studies show that the development of regional tectonic coal and intensive fault often appear complex intersection distribution phenomenon, and accompanied by different types of fold development. The structural control effect is shown to be in the vicinity of fault, the degree of fragmentation is generally decreased with the increase of distance from the fault plane. Fold develops different types of tectonically deformed coal because of difference of stress environment in different part. Layer slider nearby coal structure sliding surface receives more intense shear and compressive stress occurs brittle ductile deformation, and may appear small crumpled phenomenon.Laws of coal seam gas content in the vertical shallow depth below the upper plane extending north-south, east-west zonation, tended to increase from west to east, its distribution by the depth of the coal seam, the coal structure, faults and folds the combined effect of construction. Affect performance construct coal law on Gas Storage is less brittle deformation degree of the original bituminous coal, coal and flake fracture porosity of coal and total pore volume is small, a large hole and the hole in less developed, Gas adsorption weak, area is not conducive to the development of such coal gas occurrence; and strong brittle deformation of crushed coal and coal ductile deformation scales, crumpled mylonite coal and coal porosity and total pore volume is large, macroporous and in stomatal development, gas adsorption capacity of stronger regional development in favor of such coal gas occurrence. |
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