| According to the analysis of the existing exploration data in the 330 mining area of Xuchang Coal Mine,the geological and tectonic conditions of this area are more complex and the faults are extremely developed.Therefore,the analysis and study of the structural features and the complexity of the area not only have far-reaching significance in theory,but also have a certain current development in the development of 330 mining areas and other mining areas.Real meaning.Based on the analysis of the regional tectonic setting and the history of tectonic evolution in the study area,this paper summarizes the distribution law of geological structure development in the mining area,reveals the control effect of regional structure on coal measures in the mining area,and uses mathematical statistics to clarify the characteristics of the geological structure development in the 330 mining area.Finally,four quantitative indexes are selected and the fuzzy synthesis is adopted.The evaluation method is used to quantitatively evaluate the complexity of geological structure in the 330 mining area of Xuchang Coal Mine:(1)the control of the regional structure of the Xuchang Coal Mine resulted in the development of a group of wide slow folds and a group of Northwestern subfolds and a group of north-west high angle normal faults and the South West tilting high angle normal fault formation moving toward the north and West,which made the coal bearing strata descending westward and southward.(2)the structural evolution of Xuchang Coal Mine can be divided into 4 periods.It was Indosinian,early Yanshan,late Yanshan and Himalaya.The East-West fold structure was developed in the Indosinian period;early northwestern and northwestern fault structures were developed in Yanshan,and late Yanshan was mainly developed by eight Li bed faults;a series of smaller normal faults were developed in the early Himalayan,and the late Himalayan faults were reformed.(3)statistical analysis of structural elements using regression analysis and other mathematical statistics shows that:①the main structure of Xuchang Coal Mine is mainly fault,especially the normal fault is more developed,accounting for 98.57%,the reverse fault is less developed,the fault fall is divided into 8.97%,the small fault accounts for 91.03%,and the fold structure is less developed.The main faults are NE,near SN and NW.②the development of fracture structure in 330 mining area is not strong.The faults in the mining area are normal faults,and the faults are mainly NE and NW.The combination of fault sections is mainly stepped.The fault structure in the mining area is mainly composed of high angle faults.The fault strike is mainly NE and NW.The faults tend to be NE and NW,and the minor part is E and W.③there is a good correlation between the maximum difference of fault and the length of extension,which can be used for the basis of structural prediction,and the fault plane of the normal fault is steep,usually between 60 and 70 degrees.(4)according to the proportion of 400 x 400 m2,the contour map of the coal seam floor in the 330 mining area of Xuchang Coal Mine is divided into 44 units.Through comparison,four quantitative evaluation indexes of fault density(M),fault strength(F),fold plane strength index(D)and fractal dimension value(Ds)are selected,and the index values of each evaluation unit are analyzed,and the models are used.The result of the comprehensive evaluation method is that there are 25 units belonging to class I,7 units belonging to class II,6 units belonging to class III and 6 units in class IV,and the results obtained are basically consistent with the actual geological conditions. |
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