基于奥灰水位动态预测的煤层底板带压开采安全性评价

Safety evaluation of coal seam floor mining under water pressure based on dynamic prediction of Ordovician limestone water level

  • 摘要: 煤层底板带压开采安全性评价的核心任务是对底板突水危险性进行评估。传统突水危险性评价往往基于静态奥灰水位计算突水系数,由此得到的煤层底板带压开采安全性评价结果滞后于突水风险的变化,难以反映未来回采时煤层底板的突水风险。针对该问题,以内蒙古利民煤焦有限责任公司Ⅱ0316采区为工程背景,提出了一种基于奥灰水位动态预测的煤层底板带压开采安全性评价方法。首先,根据矿井奥灰水位观测数据绘制水位变化曲线,采用Logistic曲线对矿井奥灰水位观测数据进行拟合,以预测未来回采时的奥灰水位;然后,根据预测的奥灰水位,运用“五图−双系数法”绘制煤层底板保护层破坏深度等值线图、煤层底板保护层厚度等值线图、有效保护层厚度等值线图、煤层底板保护层承受水压等值线图,进而计算突水系数和带压系数;最后,依据“三级判别”标准进行带压开采安全性评价,绘制带压开采安全性综合分区图,划分带压开采安全区及突水危险区。研究结果表明:Logistic拟合曲线的决定系数大于0.995,表明该曲线能够准确反映奥陶系灰岩含水层在持续补给条件下的水位演化规律;基于动态预测水位获得的带压开采安全性评价结果能够前瞻性地反映未来回采时的底板突水风险,解决了基于静态水位评价时效性不足的问题。

     

    Abstract: The core task of safety evaluation for coal seam floor mining under water pressure is to assess the risk of floor water inrush. Traditional water inrush risk evaluation often calculates the water inrush coefficient based on static Ordovician limestone water levels, so the resulting safety evaluation of coal seam floor mining under water pressure lags behind changes in water inrush risk and cannot reflect the future risk of floor water inrush during mining. To address this problem, a safety evaluation method for coal seam floor mining under water pressure based on dynamic prediction of Ordovician limestone water level was proposed using mining area Ⅱ0316 of Inner Mongolia Limin Coal and Coke Co., Ltd. as the engineering background. First, a water level variation curve was drawn according to observed Ordovician limestone water level data from the mine, and a Logistic curve was introduced to fit the observed data and predict the Ordovician limestone water level during future mining. Then, based on the predicted Ordovician limestone water level, the five-map and two-coefficient method was used to draw contour maps of failure depth of the coal seam floor protective layer, thickness of the coal seam floor protective layer, effective protective layer thickness, and water pressure borne by the coal seam floor protective layer, and the water inrush coefficient and mining-under-pressure coefficient were calculated. Finally, safety evaluation of mining under water pressure was carried out according to the three-level discrimination standard, and a comprehensive zoning map of safety for mining under water pressure was drawn to divide safe areas for mining under water pressure and water inrush risk areas. The results showed that the coefficient of determination of the Logistic fitting curve was greater than 0.995, indicating that the curve could accurately reflect the water level evolution of the Ordovician limestone aquifer under continuous recharge conditions. The safety evaluation results of mining under water pressure obtained based on dynamically predicted water levels could prospectively reflect the risk of floor water inrush during future mining, solving the problem of insufficient timeliness in evaluation based on static water levels.

     

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