Quantitative Discrimination Of The Water Resisting Ability And Rock Structure Of The Main Coal Floor Seam Of Typical Mines In Pingdingshan Coalfield

With the continuous consumption of shallow coal resources,deep mining is the next development trend.In this paper,three adjacent mines in the east of Pingdingshan coalfield-No.13 mine,Shoushan No.1 mine and No.8 mine are taken as research mines,and the effective thickness,compressive and permeability properties,lithologic combination and water resistance properties of the water barrier of the main coal seam-Ji coal are taken as research objects.Through the field survey and the collection of field data,this paper studies the main control index data of the water resisting strata of the floor of the coal seam,and analyzes the spatial distribution change characteristics.Then,based on the fractal dimension,AHP and grey correlation analysis,coupled with the comprehensive weight and fuzzy variable set theory,the hierarchical structure mathematical model for the quantitative determination of the water separation ability of the coal floor slate layer is constructed.This paper makes a quantitative discrimination and spatial division of the water resisting ability of the floor slate of No.13mine,Shoushan No.1 Mine and No.8 mine.The following research results have been achieved:(1)Six main control indexes of the water separation ability of the slate layer at the bottom of the coal seam are determined:effective water separation thickness of the rock layer,complexity of the fault,overall compressive strength,core recovery rate,thickness ratio of plastic brittle rock,equivalent water separation coefficient.AHP and grey correlation analysis are used to determine the subjective and objective weights of the indexes respectively,and the comprehensive weights are identified by the coupling of them.It can be seen that the effective water separation thickness,fault complexity,compression and water resistance performance of the rock stratum are the most critical.(2)The microstructural characteristics and mineral components of the rock samples of aquiclude are analyzed by polarizing microscope and XRD diffractometer,and the physical and mechanical properties of the core of aquiclude in the coal floor of the mining area are analyzed.Due to the abundant rock core and complete data obtained in No.13coal mine,based on the analysis of its engineering geological and hydrogeological data,this paper uses FLAC^3D software to carry out numerical simulation of the disturbance and damage of the floor of Ji coal,analyzes the deformation and damage characteristics of the surrounding rock,and determines that the disturbance and damage depth of the floor is18.1m respectively.The simulation results are consistent with the monitoring results of the mining area,indicating that the simulation process is reasonable and the conclusion is reliable.The depth of floor failure of the first and eighth mines is calculated by empirical formula.(3)Based on the fractal theory,the fractal dimension values of the faults of No.13mine,Shoushan No.1 mine and No.8 mine are determined,and the spatial division of fault complexity is carried out.The results show that the complex and slightly complex areas of No.13 mine account for 10.06%,and the fault distribution in the middle of the mine is complex.In Shoushan No.1 mine,24.50%of the faults are complex and slightly complex,and the fault distribution in the north and south of the mine is complex.The complex and slightly complex area of No.8 mine accounts for 34.22%,and the fault distribution in the northeast of the mine is complex.(4)This paper studies the six main control index data of the floor water barrier and analyzes the spatial distribution characteristics.Then using the principle of Kriging software surfer to draw the isoline map of each main control index of the water separation capacity of three mine floor strata,which provides a reference for the actual production.Coupling comprehensive weight and fuzzy variable set theory are used to make quantitative discrimination and spatial division for the water separation ability of three floor slates.The results show that the strong and slightly strong area of No.13 mine accounts for 34.63%,the weak and slightly weak area accounts for 5.08%,and the southwest of the mine is relatively weak.The strong and slightly strong area of Shoushan No.1 mine accounts for 32.31%,the weak and slightly weak areas account for 28.99%,and the water isolation ability of the strata in the northwest and southeast of the mine is relatively weak.The strong and slightly strong areas of No.8 mine account for 18.52%,the weak and slightly weak areas account for 32.51%,and the water isolation ability of the strata in the middle and southeast of the mine is relatively weak.