| Based on collecting,collating and analyzing mine geology material,this paper deeply studies tentonic feature and development regularity of Qinan coal mine,and quantitatively evaluat the complexity of fault structure of Nos.72 and 10 coal seams by fractal dimension.Through the observation of underground coal wall,analysis of tectonic deformation characteristics of coal sample and log interpretation,this paper analyzes micro deformation characteristics of tectonically deformed coal(TDC)and development law of coal seam with different coal structure,discussing the main control geological factors of development and distribution of TDC.The following results and understanding are obtained.(1)The coal-bearing strata of Qinan coal mine,located in the SW section of the hinge zone of the box-like oblique at Sunan,mainly experienced three stages of tectonic stress,which NS compression at Indosinian,NWW-SEE compression at Yanshanian,and NW-SE extension stress at Himalayan period.The formation and evolution of the Yanshanian thrust nappe structure in Xusu is of great importance to the main structure of the mine,establishing the main structure of the study area and froming multidirectional fault of Sunan syncline and hinge zone of fold.In the mining area,the two fold structures of Zhangxuewu syncline and Wanglou anticline are developed.The fault structure is widely developed in the mine,mainly NE,near NS,NNE and NW four groups,which more NS and NE fault and NNE fault is the gap,extending the length of the larger fault and the main normal fault.In the middle and eastern part of the mine,the fault structure is very developed,but the northern and southern relatively low degree of development.The quantitative evaluation of fractal dimension of fault development complexity shows that the complexity of fracture structure of Nos.72 and 10 coal seams are higher,but heterogeneity,which the fractal dimension is smaller in the north and the south,while the fractal dimension is larger in the central,Western and eastern regions.(2)The coal mine is mainly composed of structural brittle deformation series by the analysis of macro-and micro deformation characteristics of TDC.The main types of TDC are cataclastic-and mortar coal,with locally developed scaly-and wrinkle coal of brittle-ductile transition-and ductile deformation series,respectively.The coal structure is divided into 3 types according to others’ study and interpretation of logging curves: type I coal includes primary coal,type II coal is weakly deformed coal including cataclastic-and mortar coal granulitic,and type III coal is strongly deformed coal,which is brittle deformation with the deformation intensity is higher than that of the cataclastic coal,brittle-ductile transition and ductile deformation.The No.72 coal seam is mainly composed of types II and III coal,while the No.10 coal seam is mainly composed of types I and III coal though the method of "three groups,horizontal and vertical comparison".(3)Distribution and thickness variation of types II and III coal of Nos.72 and 10 coal seams were discussed.It is considered that the Sunan oblique and secondary folds of the region play a major role in controlling the distribution of coal structure types through the analysis of the influence of fold structure and fault structure on coal deformation.The influence of fault structure is relatively weak,but the deformation of coal is more intense in the area of fault dense or large fault development,as well as superimposed structure,forming type III coal. |
