水力联系系数法定量评价含水层之间水力联系

Hydraulic Connection Coefficient and Quantitative Evaluation of Hydraulic Connection Between Aquifers

为了定量研究与评价含水层之间地下水水力联系程度,首次提出了水力联系系数C(hydraulic connection coefficient)的概念。将水力联系系数C定义为观测孔目的含水层水位降深与该观测孔位置抽水含水层水位降深的比值。通过水力联系系数,可定量评价某含水层水平上同层之间和垂向上不同含水层之间的水力联系程度。依据鄂尔多斯盆地白垩系洛河组各含水层段的水力联系系数C值,将含水层之间水力联系分为5个等级。其中,0.000 0≤C<0.062 5,0.062 5≤C<0.125 0,0.125 0≤C<0.250 0,0.250 0≤C<0.500 0,C≥0.500 0,分别代表水力联系等级为极弱、弱、中等、强、极强。以高家堡井田钻孔抽(放)水试验数据为例,采用水力联系系数和观测孔水位响应时间两个指标定量评价了区内巨厚层状非均质洛河组含水层内部水力联系。结果表明:洛河组中上段水平同层之间的水力联系系数分别为0.373 0、0.413 8,观测孔水位响应时间较短(约为5 min),水力联系强;洛河组下段水平同层之间水力联系系数分别为0.440 1、0.491 1,观测孔水位响应时间较短(为9~20 min),水力联系强;洛河组中上段与下段垂向水力联系系数分别为0.000 2、0.007 2、0.089 7,观测孔水位响应时间较长(大于60 min),水力联系极弱至弱。

In order to quantitatively evaluate the degree of groundwater hydraulic connection between aquifers, the concept of "hydraulic connection coefficient" C is first proposed. Based on the drawdown of groundwater level in full penetrating wells during the steady-state pumping test when the groundwater level is stable, the hydraulic connection coefficient C is defined as the ratio of the drawdown of groundwater level of the target aquifer to the drawdown of groundwater level of the pumping/dewatering aquifer in the observation borehole. The hydraulic connection coefficient can be used to quantitatively evaluate the degree of hydraulic connection between two points in different directions and different distances on the aquifer plan, and also between different aquifers in the vertical direction. According to the hydraulic connection coefficient C value of the aquifers in Luohe Formation in Ordos basin, the degree of groundwater hydraulic connection between the aquifers is divided into five grades: Among them, 0.000 0≤C<0.062 5, the hydraulic connection is very weak;0.062 5≤C<0.125 0, the hydraulic connection is weak;0.125 0≤C<0.250 0, the hydraulic connection is medium;0.250 0≤C<0.500 0, the hydraulic connection is strong;C≥0.500 0, the hydraulic connection is very strong. Taking the data of pumping test and dewatering test in Gaojiabu mine field as an example, the hydraulic connection coefficient and the response time of groundwater level in the observation borehole beginning to fall are used to quantitatively evaluate the internal groundwater hydraulic connection of the thick and layered Luohe Formation. Among them, when the hydraulic connection coefficient of the middle-upper layers in Luohe Formation is 0.373 0 and 0.413 8 respectively, and the response time of groundwater level in the observation borehole beginning to fall is very short(about 5 min), the groundwater hydraulic connection is strong;The hydraulic connection coefficient of the lower layers in Luohe Formation is 0.440 1 and 0.491 1, respectively, and the response time of groundwater level in observation borehole beginning to fall is short(9-20 min), the groundwater hydraulic connection is strong;When the hydraulic connection coefficient between the middle-upper and lower layers in Luohe Formation is 0.000 2, 0.007 2 and 0.089 7, respectively, and the response time of groundwater level in the observation borehole is longer(more than 60 min), the groundwater hydraulic connection is weak or very weak.