基于改进AHP和熵权法耦合的风化基岩富水性预测方法

Water abundance prediction method of weathered bedrock based on improved AHP and the entropy weight method

  • 摘要: 我国西北地区侏罗系风化基岩含水层是矿井充水的主要含水层,多次煤矿顶板突水事件均与该含水层有关。侏罗系风化基岩具有结构疏松、孔隙度大、岩层渗透性强和裂隙发育的特点,导致了其富水性在空间上极不均一,如何科学的评价预测侏罗系风化基岩富水性成为矿井防治水工作中急需解决的难题。以柠条塔井田南翼为例,分析了风化基岩富水性的控制因素,选取风化基岩顶面标高级别指数、岩性组合指数、风化指数和岩芯采取率指数4个指标作为风化基岩富水性预测的主要指标。针对AHP在确定权重时重专家经验而对指标实测数据特征考虑不够和熵权法在确定权重时重客观数据而未顾及专家经验的不足,提出了将改进AHP和熵权法通过最小二乘法耦合起来计算富水性预测指标权重的方法。利用柠条塔井田南翼172个钻孔地质资料和其中41个风化基岩抽水试验资料,进行了基于改进AHP、熵权法和改进AHP与熵权法耦合的柠条塔井田南翼富水性分区预测及结果比较分析。结果表明,基于改进AHP权重确定方法、熵权法权重确定方法和耦合两者的权重确定方法预测的富水性类别和41个抽水钻孔的富水性吻合度分别为68.29%,70.73%和92.68%,即就是基于改进AHP和熵权法耦合确定预测指标权重的风化基岩富水性预测方法效果最好。该研究成果为含水层富水性评价预测提供了一种新方法。

     

    Abstract: The Jurassic weathered bedrock aquifer in Northwest China is the main aquifer for filling water in coal mines. Many water inrush disasters in the coal mines are related to the aquifer. The inhomogeneity of the aquifer is de- termined by its features of loose structure,large porosity,high permeability and fractures. How to accurately evaluate and predict the water abundance of Jurassic weathered bedrock is a scientific challenge in mine water prevention. The south wing of the Ningtiaota coalfield was taken as an example to analyze the water abundance of weathered bedrock and its controlling factors. Four indexes of weathered bedrock including top-level index,lithologic association index, weathered index and core rate index were selected as the main indexes for water-richness prediction. In order to over- come the shortcomings of AHP which emphasizes expert experience in determining weights but does not consider the characteristics of measured data, and the entropy weight method which emphasizes objective data in determining weights without considering expert experience,a method of calculating the weight of water abundance prediction index by coupling improved AHP and entropy weight method using least square method was proposed. Based on the 172 borehole geological data and the 41 weathered bedrock pumping tests data in the south wing of the Ningtiaota coalfield,the zoning of water-richness has been predicted. Also,its results were compared and analyzed with the im- proved AHP,the entropy weight method and the coupling of the improved AHP and the entropy weight method. The re- sults show that the water abundance accuracy predicted quantitatively by the improved AHP weight determination method,the entropy weight determination method and the coupling method are 68. 29% ,70. 73% and 92. 68% re- spectively. The result indicates that the coupling of the improved AHP and the entropy weight method can be used to predict the water-richness of weathered bedrock accurately. The method also provides a new way for the evaluation and prediction of aquifer water abundance.

     

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