Study On Evaluation Method Of Fault Hydraulic Conductivity And Influence Of Mining Activation

The mining of North China type coal fields is generally threatened by the Ordovician limestone water in the floor,And the main form of Ordovician limestone water inrush is through the floor fault as a water channel.Conducting pre mining evaluation of fault hydraulic conductivity and research on mining activation is of great significance.This thesis takes the seventh mining area of Dongtan Coal Mine in Yanzhou City,Shandong Province as the research background,with the goal of preventing Ordovician limestone water inrushing through fault.Around scientific issues include pre mining fault hydraulic conductivity evaluation and whether the fault is activated during mining and changes its hydraulic conductivity due to activation,theoretical analysis,formula derivation,numerical simulation and other methods are used to conduct in-depth research on the method of evaluating the pre mining zoning of fault hydraulic conductivity,the Temporal and spatial laws of mining activation of floor faults and the impact of mining activation on fault hydraulic conductivity.The results obtained are as follows:(1)On the basis of analyzing the factors that affect the hydraulic conductivity of faults,using the research results of fault sealing theory,four factors,namely SGR value,mudstone plastic deformation index(Im),fault opening and closing factor(If),and fault rock diagenesis index(IFT),were selected as evaluation indicators.Combining single indicator evaluation criteria and multi indicator superposition classification criteria,a pre mining fault hydraulic conductivity zoning evaluation method was established.(2)The pre mining hydraulic conductivity zoning evaluation method was applied to four faults in the study area,and the permeability coefficient of the fault zone in the study area was predicted using the fitting formula between the natural gamma ray data of the drilling holes in the study area and the measured permeability coefficient.The results were compared with the hydraulic conductivity evaluation results,and the two were highly correlated;The evaluation results show that the overall pre mining hydraulic conductivity of the faults in the study area is low.(3)Introducing fault failure factors(υ)Concept into the mechanical model of fault activation in mining floor established by predecessors,through The value of υdetermines whether the fault is activated.The spatio-temporal laws of fault activation is reflected by the changes of υ value with mining distance and buried depth of fault zone as independent variables respectively;By utilizing the programming function of Matlab,the data quantification analysis and calculation of the model were achieved,and the spatio-temporal laws of fault activation in the mining floor under the influence of fault dip angle,internal friction angle,and mining depth were studied.(4)The fracture grid function of GDEM numerical simulation software is used to simulate the process of changes in the hydraulic conductivity of floor faults caused by mining.By monitoring the changes in the opening of cracks at different depths of the floor fault zone during mining,the activation process of coal seam floor faults and the changes in hydraulic conductivity of fault zones are revealed.(5)Based on the theoretical research results of the changes in hydraulic conductivity of mining floor faults,Analyzing the mining activation characteristics of faults in the study area based on their characteristics,and a representative FJ130 fault is selected to simulate the process of hydraulic conductivity changes during mining,providing a basis for safe coal mining.This thesis has 71 figures,21 tables,and 98 references.