Characteristics Of Tectonically Deformed Coal And Influence On The Occurrence Of Gas Of Wugou Coalmine, Huaibei

Based on the systematic study of stratum and tectonic characteristics, structuralcombination types and tectonic evolution of Wugou coalmine,37tectonically deformedcoal (TDC) samples of different deformation degree of coal No.10have been collected. Inreference to previous classification methods, the macroscopic, microscopic andultra-microscopic deformation characteristics and pore structural characteristics have beenfurther studyed through the description of macroscopic coal samples, microscope test,mercury injection experiment and SEM. Combined with structural characteristics,deformation and pore structural characteristics of TDC and the distribution of gas, thecontrol of structures to TDC and gas properties of TDC have been systematically studied.On this basis, the influence of different TDC types on the occurrence of gas has beendiscussed.The TDC in Wugou coalmine can be classified in6types, cataclastic structural coal,mortar structural coal, granulitic structural coal, powder structural coal, scaly structuralcoal and wrinkle structural coal. The TDC in coal No.10is relatively developed and themain types of which are cataclastic structural coal, mortar structural coal and granuliticstructural coal of brittle deformation. With the strengthening deformation, native structureand stratification will peter out; the granularity of TDC becomes smaller; the fracturesbecomes more, unstable and changeable; the friction surfaces become smooth and brightwhich wrapped the coal in; the sliding striation tend to be more obvious; the deformationof coal changes from brittle to ductile. The microscopic deformation characteristics alsoshow some changes. Components of coal is changes from clear to broken, difficult toidentify and then crumpled; the fractures become more, smaller, unstable and curving.With the strengthening deformation of coal, total pore volume, porosity and medianpore diameter will increase firstly, then lessen, and then increase again and becomes moreand more discrete. The pore specific surface area is stabilized on the whole. The porevolume of indigenous coal, cataclastic structural coal and mortar structural coal iscomposed of micropore and transition pore, and the connectivity of pore is poor; the porevolume of granulitic structural coal, powder structural coal, scaly structural coal andwrinkle structural coal is composed of macropore, mesoporous and micropore, and theconnectivity becomes better. It is distinct that the control of different deformation types tomacropore and mesoporous. It is weak that the control of less brittle deformation and less shear deformation to macropore and mesoporous, just increase pore volume of macroporeand mesoporous in a little range. While strong brittle deformation, strong tenacitydeformation and strong shear deformation increase pore volume of macropore andmesoporous in a much range. Because of that the macropore and mesoporous are the mainseepage pore, indigenous coal, on an equal footing, cataclastic structural coal, mortarstructural coal and scaly structural coal can acommodate more free gas, and granuliticstructural coal, powder structural coal and wrinkle structural coal can’t.