Study On Hydrogeological Effect Of Closed Pit Mine

According to the national policy of de capacity requirements,Zhaogezhuang coal mine located in Guye District of Tangshan city will be closed and exited at the end of2019.Due to historical reasons,Zhaogezhuang coal mine and other adjacent mines have not left enough security coal pillars above-650m of the boundary coal pillars,which are connected by the mining damage of each mine.Therefore,certain drainage measures should be reserved to control the rise of water level in the mine during the pit closure process In order to ensure the safety production of adjacent mines.Therefore,based on the current situation of the mine and relevant policy documents,and on the basis of the research on the mechanism of the rise of water level in the mine,this paper analyzes the time when the water level rises to the warning water level,the change of water inflow and the strength change of boundary coal pillar under the effect of mine water immersion,studies and evaluates the hydrological and geological effects caused by mine mining,and puts forward some suggestions on the prevention and control of water,so as to provide reference for the safe closure of similar mines It can be used for reference.The research results are as follows:(1)Based on the analysis of the mining range of Zhaogezhuang and adjacent mines,according to the data of the destruction location of the boundary coal pillar and the analysis of FLAC3D numerical simulation method,the-570m is finally determined as the lowest position of the destruction communication of the boundary coal pillar,and the-575M is positioned as the warning water level of the water level rising after the mine is closed.According to the statistics of goaf area below the warning water level elevation by coal seam and level,the accumulated water in goaf between-1200m and-575M after well closure in Zhaogezhuang is 10529241m3,which provides the basis for calculating the water level rise time after well closure in Zhaogezhuang.(2)Based on the analysis of the water diversion space after the closure of Zhaogezhuang mine,the groundwater dynamics formula and the Visual MODFLOW numerical simulation method are used to calculate that the water level of Zhaogezhuang mine rises to the warning water level around 430 days after the closure of the mine,and the mine water inflow is 10.98m~3/min,and the discharge through the aquifer to the adjacent mine Linxi mine is 1.56m~3/min.(3)According to the analysis of one month's soaking test results of coal pillar samples,the tensile strength and compressive strength of coal samples after soaking in mine water show a downward trend,and the decline curve is nearly flat when the original strength is reduced to 60%.Combined with the calculation formula of"upper three zones"and FLAC3D numerical simulation method,the stability of boundary coal pillar is analyzed,and it is considered that the reserved width meets the requirements.(4)According to the corresponding regulations,combined with field investigation and literature research,the hydrogeological effects caused by mine mining are evaluated,and finally four first-class indexes and 15 first-class indexes including geological disasters,aquifer,landform and landscape,land resources are determined According to the principle of priority of the upper level,as long as one index conforms to a certain level,it is defined as that level.Finally,it is determined that the mining activities in Zhaogezhuang mine have a serious impact on the hydrogeological effect.This paper consists of 62 figures,31 tables and 87 references.