Study On Influence Of Mining On Underground Water Flow System In Luohe Iron Mine

Luohe Iron Mine is located in Lujiang County,Anhui Province.At present,more than-560m～-455m horizontal roadway has been developed in the east of the deposit.The first phase of the project is designed to be mined to-620m elevation,with a service life of 41 years.The mine is located in the hilly area,and the continuous exploitation of the mine for many years leads to the decrease of underground water resources in the mine area,thus affecting the underground water flow system.Based on the numerical simulation method to study on the influence of mining on the groundwater flow system,understand the mechanism of changes of groundwater flow system,find out the changes due to mining of underground water flow and its influence on regional hydrogeological conditions,the correct analysis and understand these effects,and provide theoretical basis for rational development of mineral resources.The main research achievements are as follows:(1)According to the properties of underground water-bearing media,occurrence characteristics of groundwater and stratigraphic lithology,the underground aquifer in the study area can be vertically divided into:weak aquifer group of loose rock type pore water;Volcanic clastic rock type pore fissure water aquifer group;Volcanic clastic rock type waterproof layer group;There are three aquifer groups and two aquifer groups:bedrock fissure water aquifer group and intrusive rock type aquifer group.The main drainage object of the deposit is the bedrock fissure water aquifer group,and the affected area of the falling funnel mainly occurs in the bedrock fissure water group and the pyroclastic rock pore fissure water aquifer group affected by the overflowing supply.(2)Through the establishment of heterogeneous anisotropic and unstable quasi-three-dimensional numerical simulation model of underground water flow in the study area,the stable value of mine water inflow is predicted to be about 4560m~3/d.(3)At the end of the service period of the deposit(41 years),a groundwater drop funnel with a radius of about 1970m was formed in the second aquifer group(bedrock fissure water)by mining,and the central water level was reduced to-620m,that is,the lowest mining level elevation of the first stage project,affecting an area of about12km~2.In the first aquifer group(clastic rock pore fissure water)caused by the mine mining area as the center of the groundwater drop funnel with a radius of about 1260m,the central water level additional depth drop of about 15m,affecting an area of about5km~2.(4)After mining,the groundwater flow field of the first and second aquifer groups in the study area flows from around the mining area to the mining center,showing obvious three-dimensional flow characteristics,and the flow between aquifers occurs.Mine mining has the greatest influence on bedrock fissure water of the second aquifer group,followed by pore fissure water of clastic rock of the first aquifer group,and pore water of loose rock.(5)Mining will cause certain damage to the spatial structure of underground water-bearing media and change its properties,which are mainly manifested as the change of permeability,water storage type and aquifer thickness,coupled with the influence of pit drainage.The influence of mining on the groundwater flow system in the study area is mainly manifested in the change of the spatial structure and inherent characteristics of the water-bearing medium,the change of the water circulation system of the groundwater resources,the change of the groundwater recharge,runoff and discharge conditions.