Hydrogeological changes caused by opencast coal mining in steppe zone: a case study of Shengli 1 open-pit coal mine

摘要

The exploitation of coal resources can lead to change of regional environment, and open-pit mining makes even more direct impact on vegetation, topsoil, surface water and underground water in grass area. Studying the change of hydrogeological condition caused by open-pit mining is beneficial for rational utilization of water resource in grass area and guaranteeing normal exploitation of open-pit mine. In this study, the Shengli 1 open-pit coal mine with typical hydrogeographical features, locating in typical meadow steppe area, was taken as researched area. Through collecting basic mine production data, such as annual output, drainage quantity, water inflow, the water inflow (including static- storage and recharge rate) of mine was predicted and calculated by horizontal catchment channel method, big well method and replenishment quantity method, respectively. This study investigates the hydrogeological condition changes of open-pit coal mine in grass area during production process. Results show that the static storage of hydrogeological unit exerts great impact to coal mine exploitation and production in early stage, while recharge rate exerts continuous influence to the whole mining process. As the quarternary loess in earth surface of steppe area is thick, and phreatic layer has a direct association with mining pit, the replenishment quantity method can achieve the most accurate calculation; the influence of open-pit mining to geohydrologic condition is mainly determined by aquifer hydraulic conductivity and mining depth.