Study Of Structural Control Mechanism On Groundwater In The North Mining Area Of Huainan Coal Field

Huainan coalfield is located in the southern margin of the north China coal field,and experienced multiphase tectonic superposition, complex in structure. The main body of coalfield is a compound synclinal structure, the folded strata and fracture structure is extremely development.Tectonic movement can not only control the structure of the aquifer system form, but also directly control the dynamic conditions of groundwater,especially a large number of NE to NNE direction of the normal fault formed in Himalayan period that formed a group of step fault structure in the study area which have the most obvious effect for the modification of the aquifer. Therefore, it is necessary to do some research on the structural control mechanism on groundwater in the region,and the study it’s also very meaningful.In this paper, taking Kouzidong mine, Liuzhuang mine, Xieqiao mine and Zhangji mine of north Huainan coalfield as the research object,and the research scope covers Fudong mining area and Panxie mining area. Using the method of tectonic evolution and analysis of hydrogeological structure system,from the following three aspects which were Huainan coalfield regional tectonic characteristics and structural evolution process,structural control mechanism on groundwater,division of hydrogeological segment.And conclusions are obtained as follows:1. In the aspect of tectonic characteristics:The structural control mechanism on groundwater can be summarized as "hydrogeological structure system control of the underground water system".The present tectonic framework of huainan coalfield is the result of superposition of multiphase tectonic movement,such as Indosinian movement, Yanshan movement and Himalayan movement, etc.The number of geological structures of NE to NNE direction were the most and the nearly EW and NW to NWW direction took the second place.The bedrock surface morphological characteristics in the study area is high to the southeast, low to the northwest.This is the result of differentiating weathering of the fold which is produced by the movement of nappe structure;2. How does the geological structure control groundwater:The Caledonian movement and Variscian movement control the deposition of the bedrock aquifer in this area. Large tectonic movements as the Caledonian movement and Variscan movement control the deposition and formation of the bedrock aquifer. Late again experienced multiphase squeezing and tension which modified the bedrock aquifer on bending and cutting, and this enhances the water-abundance ability of the bedrock aquifer. Large block water structure such as Fufeng thrust fault, often as hydrogeological unit boundaries, and large deep fractures can communicate each aquifer,and they also control the characteristics of groundwater recharge, runoff and discharge;3. In the aspect of block division of hydrogeological units:The study area is divided into "North" segment,"South" segment,"Central-west" segment and "Central-east" segment according to the difference of hydrogeological conditions and hydrodynamic in different locations in the study area. Then analyzed the control of internal hydrodynamic conditions by geological structure in each block.At last, combining with the actual production in mines, summarized the control function of mine water inrush by fault,and thinks that water inrush positions were often near the deep fracture or secondary fault.And the positions on deep fracture and secondary fault were often the hidden troubles of mine water disaster. Suggests an grouting reconstruction in these places.