| Coal industry is pillar industries of Shanxi province. Coal-bearing area of the entire province is6.2square kilometers. It is forty point four percent of Shanxi province land area. Due to the objective historical reasons, the coal industry of Shanxi in a brilliant also accumulates a lot of problems at the same time. There is large harm to water environment and water resources. Shanxi minable seam general mainly occurs in Taiyuan formation of Carboniferous and Shanxi formation of Permine. There are both coal and water in formation. Coal seam mining fissure zone formed by caving will inevitably cause the destruction of taiyuan and shanxi formation overlying aquifer. For the underlying strata of the ordovician strata, if can take reasonable mining methods and strict management measures, it will be able to effectively avoid the widespread destruction of karst aquifer, and in the process of coal mining, underground water with pressure area inrush would be the biggest threat for the karst aquifer. The typical method is reserve protection coal pillar, but it is a waste of coal resources and dangers remain. It is a ideal method that it can make full use of karst water resources in mining step-down at the same time, reduce the pressure of ordovician karst water to the range of security. Based on longquan coal mine as an example, this paper research karst water optimization scheme and its antihypertensive effect which satisfy the requirement of mining safety through combining with coal mine and the surrounding water.Longquan mine (hereinafter referred to as "mine") locates in LouFan County, Shanxi Province, administrative division is LouFan County Long Quanxiang jurisdiction. The jurisdiction of the administrative division is LongQuan County LouFan County. North and south of mining field wides5.747kilometers, longs8.635km, and covers an area of35.2379km2. It is mainly excavate NO.4coal. The coal seam from ordovicia lower confining bed average thickness is about138m, the northeast which is the thinnest of all field place, about117m thick. As coal seam to the north east plunging, hydraulic pressure of the lower confining bed gradually increases, inrush coefficient increases, and gradually the security of under pressure mining reduce. No.4coal seam can be divided into two parts according to pressure of coal seam, namely the water inrush coefficient0-0.06MPa/m and0.06-0.1MPa/m. The region has developed tomographic which are named F12, F13, F14and collapse column which is named X3, providing the possibility for water inrush danger zone of the coalfields with pressure, In this paper, we consider the field range0.06-0.1MPa/m region by hydrophobic step-down method in advance for the ordovicia groundwater environmental impact.Based on the hydrogeological conditions in the study area of the field investigation and test, analysis the study of dynamic characteristics of groundwater, the karst aquifer medium system is generalized, and set up the Longquan mine coal karst groundwater heterogeneous anisotropic three-dimensional conceptual model of unsteady flow. First, when "big well method" is applied to0.06-0.1MPa/m to inrush coefficient of0.06MPa/m in this section need released to the amount of water, and then used the Visual Modflow software to predict mining after5years hydrophobic step-down karst groundwater level change rule, for the rational development and utilization of karst water in the study area provides scientific argument and get the following conclusions:1. Area of central water coefficient of water inrush which is between0.06-0.1MPa/m site is about1.1km2. The karst water table originally for1119-1123m, the water inrush coefficient reaches0.06MPa/m, the water level at least reduced to1040-1100m. Therefore, those3decompression Wells (CS1、 CS2、CS3), step-down well drain water after the calculation of3000m3/d.2. Establish a numerical model of groundwater flow field through using VISUAL MODFLOW software, and the model is to identify and test more accurate fitting of the groundwater environment, predicted mine hydrophobic buck mining5years and9years of karst water level.3. In the model,5years later, the formation of precipitation funnel to CS1, CS2, CS3as the center, the water level drawdown funnel center is about45m, go on, downstream water level drawdown gradually become smaller, the maximum effect of upstream distance of about1.5km, the greatest impact downstream distance of about1.9km, the greatest impact crater on the left side of the distance of about1.6km, the greatest impact on the right side of the distance about2.4km, influence area is about14.6km2.4. In the model,9years later, water level drawdown funnel center is about61m, go on, downstream water level drawdown gradually become smaller, the maximum effect of upstream distance of about2.2km, the greatest impact downstream distance of about2.4km, the greatest impact crateron the left side of the distance of about2.0km, the greatest impact on the right side of the distance of about3.1km, influence area is about22.8km2. |
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