Analysis Of Water Resistance Capacity And Risk Assessment Of Water Inrush In Coal Floor Of Qianbei Mining Area

Southwest coal resources play an important role in the development and utilization of national resources.As Guizhou Province is a large coal storage province in Southwest China,the safe production of its coal resources is an important task.However,because the coal seams in Guizhou Province mainly occur in the Permian Longtan Formation,the Permian Maokou Formation — a set of strong water-rich karst aquifers,exists in underneath the coal seam.And the lower coal seams in parts of the Qianbei mining area lack of Emeishan basalt,so it will be extremely easily suffered the threat of water inrush from this set of aquifers when the coal seam is excavated.In addition,the aquifuge of coal seams in the northern Guizhou area is often unevenly distributed in space and having large fluctuations.So the water resistance capacity of the aquifuge is unevenly distributed.While the hydrogeological conditions of the mining area are different than those of the North China mining area.Therefore,selecting the methods and evaluation indexes of the water resistance capacity of aquifuge and the water inrush risk assessment cannot be same as in the study north mine of China.On the other hand,there were few studies on the evaluation of the water resistance capacity of aquifuge,especially in the Southwest mining area.Therefor,it not only is significant important for safety production of coal resources of the Southwest karst area to use reasonable theoretical methods and indexes in the analysis of water resistance capacity of aquifuge and to construct a set of reasonable indexes of a water inrush evaluation based on the mining conditions in the Southwest karst area,but it also have important guiding significant for the study of the water resistance capacity of aquifuge and the assessment of water inrush risk in the southwestern karst area.In this paper,Longfeng Coal Mine in Qianbei Mining Area was taken as an example.According to the depth of the coal seam,the number of lithological combinations of the aquifer and the thickness of the coal seam,the study area were divided into 8 sub-areas.Using the UDEC established a simulation model of coal seam excavation in each zone and calculated the depth value of the floor pressure failure zone in each zone.Combing with the linear regression theory modified the empirical formula and solved the depth of the pressure failure zone of the drill holes in each zone.It overcomes shortcomings of incomplete consideration only using empirical formula of the depth of mine pressure failure zone.On the basis of the above research,the thickness of the aquifuge under the rock pressure failure zone,the thickness of the hard rock under the rock pressure failure zone,the number of lithological combinations of the aquifuge,the consumption of drilling flushing fluid,RQD value,mudstone ratio,and structural analysis Dimension value and structure distribution were used as the evaluation index of the water resistance capacity of the aquifuge of the coal seam floor.An evaluation model of the water resistance capacity of the aquifuge based on the entropy weight theory was established,and combing with GIS,the water resistance capacity of the aquifuge of the 11 th coal seam floor in Longfeng Coal Mine was comprehensive evaluated and zoned.Based on the research on the water resistance capacity of the aquifuge,combing with the hydrogeological characteristics of the floor karst confined aquifer,the water inrush risk assessment of the coal floor was realized based on the non-linear mathematical theory-entropy weight method.The above researches have achieved the following results:First,according to the geological and hydrogeological conditions of the Qianbei mining area,an evaluation index system for water resistance and water inrush assessment of coal seam floor in Qianbei mining area in Guizhou has been established,which makes up for shortcomings by directly adopting evaluation and indexes of the North China coal mines.And it provides main reference value for the study.Moreover,using numerical simulation calculated value of the empirical formula,which overcomes the error caused by incomplete consideration of factors when directly using the empirical formula to calculate the depth of the middle mine failure zone in the northern Guizhou mining area.Thirdly,The non-linear mathematical method—entropy method was used to realize the multi-factor fusion analysis,and the GIS technology was used to realize the comprehensive presentation and expression of multiple indicators.The evaluation results provide an important reference for safe production in mining areas.