Vulnerability Assessment Of Coal Floor Groundwater Bursting Based On FAHP-EWM

The fifth coal mine of Pingdingshan Mining Group is situated on recharge-runoff area of Pingdingshan karst water system,the limestone karst is developed and the water-abundance is good.As well as abundant karstic water supply and complex hydrogeological condition,the mining and production often sustain threaten from confined groundwater of Taiyuan Formation and Cambrian limestone.There have happened 64 times water inrush in history,and made great financial losses.During the deep coal mining process,water pressure grow and water inrush risk increase.Therefore,analysis and research deep hydrogeological condition,and to find out karst development law of Cambrian limestone,objectively evaluate 2-1# coal floor karstic water inrush risk,are the problems to be solved.Based on the analysis of geology and hydrogeology condition in the fifth coal mine,this paper summarizes the karst development law of Carboniferous and Cambrian limestone.Combined with typical floor water inrush cases over the years,analysis the cause of limestone confined water inrush,and determine the five main influencing factors of the water inrush from the 2-1# coal seam,including Cambrian limestone water pressure,Cambrian limestone karst development intensity,equivalent thickness of effective water resistant layer,brittle thickness of effective water resistant layer and fault fractal dimension.This paper apply FAHP-EWM,which take into account subjective and objective weights,to calculate the comprehensive weights of the main factors,and use vulnerable index method to build the mathematical model,which to evaluate the coal floor water inrush risk of fifth coal mine.Taking ArcGIS as platform,establish the five main factors database,and standardize and topology weighted stack.And then create the thematic maps and normalized maps,and comprehensive evaluate Cambrian limestone karst water inrush risk.According to the vulnerability index,and combine hydro-geological conditions of coal mine and the mining succession plan,finally create the 2-1# coal seam floor Cambrian limestone karst water inrush risk partition map of the fifth coal mine.And divide the field into 5 partitions,water inrush vulnerable zones,less vulnerable zones,transition zones,less safety zones and safety zones.The Ji-4th mining area depth,itswater pressure is great,and it is affected by Guodishan fault and its branches,it is likely outbreak water inrush,and the areas belongs to water inrush vulnerable zones.The Ji-4th mining area and Guodishan fault effect-zone,with high water pressure and the thin aquiclude,it is less likely outbreak water inrush,and the areas belongs to water inrush less vulnerable zones.The 3th level,with poor Cambrian limestone water-abundance and thick aquiclude,there are dangers in mining under pressure.Other areas have been mined,no damage.