减少矿产资源开发过程中水资源损失是生态脆弱矿区水资源管理的重点，量化地下水位埋深与潜水蒸发速率关系，可为西部干旱矿区水资源保护提供科学思路。以隔水岩组厚度与导水裂隙带高度之差，划分了榆神矿区煤层开采地下水位变化趋势分区;以水位埋深变浅区覆盖的风积沙为试样开展潜水蒸发试验，分析蒸发过程及不同水位条件下潜水蒸发规律;通过在水分特征曲线的转折点处构建双切线，推导求取地下水埋深上限阈值的解析公式;采用漏斗法测定榆神矿区风积沙的水土特征曲线，利用最小二乘法求取特征参数，求取榆神矿区煤层开采区地下水埋深上限阈值。结果表明:榆神矿区地下水位变化趋势可分为3个区，即水位埋深变浅区、过渡区和水位埋深增加区。水位埋深变浅区多位于榆神三、四期规划区，此区域水位埋深<4 m的面积占矿区面积的59.1%，开采沉陷极易造成地下水浅埋或出露;榆神矿区风积沙蒸发过程可分为2个阶段，即稳定蒸发阶段和水汽扩散阶段，地下水位埋深0.5 m左右时蒸发过程中的水分传输机制发生了转变，蒸发进入水汽扩散阶段;在稳定蒸发条件下建立了土壤水分运移方程，推求了地下水埋深上限阈值计算公式，地下埋深上限阈值与毛细上升高度和进气压力值有关，在数值上等于表层土与地下水之间毛管水力联系中断时表层土的基质势;地下埋深上限阈值可以通过van Genuchten方程的拟合参数α，n来求解;利用实测风积沙水土特征曲线的参数，确定榆神矿区地下水埋深上限阈值为50 cm，与蒸发试验结果一致。水位埋深变浅是中深部煤层开采遇到的普遍问题，对于干旱半干旱地区的榆神矿区而言，控制合理的水位埋深上限已成为煤层开采中需要面临的新的科学问题。

Reducing the water loss during coal mining is the key task for water resource management in the ecologically fragile coal mining areas.Quantifying the relationship between the buried depth of groundwater table and phreatic evaporation rate can provide some scientific thoughts for mining in arid areas with water protection in western China.According to the difference between the thickness of the impermeable layer and the height of the water conducting fissure zone,this paper divided the groundwater level variation trend in Yushen mining area into different parts.A series of tests were conducted to analyze the process of groundwater evaporation and the law of phreatic evaporation at different groundwater levels.By constructing two tangent lines at the turning point of the water characteristic curve,it deduced the analytic formula about the upper limitation threshold of the buried depth of groundwater table.The soil and water characteristic curve of aeolian sand was measured with the funnel method in Yushen mining areas,based on which,the limitation threshold of groundwater buried depth in Yushen mining area was obtained.The results show that the trend of groundwater table changes in Yushen mining area can be divided into three parts,which include shallower region,the transition region and deeper region.The most of groundwater shallower region locates at the Phase III and Phase IV planning areas in Yushen.The areas with the depth of groundwater level less than 4 m accounts for 59.1% of the mining areas,the mining subsidence easily causes groundwater to be buried shallow or exposed.The evaporation process of aeolian sand in Yushen mining areas can be divided into two stages,namely,the steady evaporation stage and the water vapor diffusion stage.The water transport mechanism changes when the groundwater level is about 0.5 m,and the evaporation turns to the water vapor diffusion stage.The equation of soil water transport was established under the condition of steady evaporation,and then the calculation formula of upper limitation threshold of groundwater depth was deduced.The upper limitation threshold of groundwater depth is related to the height of capillary rise and the air-entry pressure,which is equal to the matrix potential of topsoil when the hydraulic connection of capillary between topsoil and groundwater is broken.Furthermore,the relationship between the upper limitation threshold of groundwater depth and the fitting parameters α,n of van Genuchten equation was established.Based on the parameters of soil and water characteristic curve of aeolian sand,the upper threshold of groundwater depth in Yushen mining areas was confirmed to be 50 cm,which is in common with the experiment results.It is a common problem that the buried depth of groundwater table become shallower during the mining of mid-deep coal seams.For Yushen mining areas,being located in the arid and semi arid areas,controlling the upper limitation of buried depth of groundwater table has become a new scientific problem to be solved in the mining of coal seams.

1 榆神矿区水位变化分区

2 潜水蒸发规律

   2.1 潜水蒸发试验

   2.2 潜水蒸发过程

   2.3 不同埋深条件下潜水蒸发

3 矿区地下水埋深上限阈值的确定方法

   3.1 矿区地下水埋深上限阈值的概念

   3.2 地下水埋深上限阈值的确定

4 榆神矿区地下水埋深上限阈值

5 结论