山西庞庞塔矿地下水化学特征及含水层间水力联系分析

依据矿区补勘钻孔抽水取得的水质化验资料,重点对影响煤层开采的奥陶系中统石灰岩岩溶裂隙含水层和太原组灰岩岩溶裂隙含水层进行了水化学特征分析,结果发现,奥陶系峰峰组含水层中SO42-离子含量普遍较高,大部分地段高于HCO3-离子含量,阳离子以Ca2+和Mg2+离子为主,水化学类型以SO4-Ca· Mg型为主;上马家沟组含水层SO42-离子含量较峰峰组岩溶裂隙水明显下降.根据各钻孔水质化验的主要离子成分、矿化度、总硬度及水化学类型进行各含水层间的水力联系分析,认为峰峰组含水层与上马家沟组含水层、太灰含水层与奥灰含水层水力联系均较弱.该研究可为矿井开采中开展水害防治提供参考.     

水力联系系数法定量评价含水层之间水力联系

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。     

利用水文地质测井方法确定钻孔间含水层的水力联系

用水文地质测井(下简称水文测井)方法解决钻孔间含水层的水力联系,除用一般水文测井方法外,还需把扩散法与提捞法进行合理的配合使用,并在含水层上做井中激发极化二次场衰减曲线。工作方法为:首先分别在两个钻孔进行水文测井,把含水层位置、厚度和钻孔中含水层间的补给关系确定出来;然后选择涌水量较大的钻孔作为提水孔或抽水孔,另一个钻     

山东省汶泗河冲洪积平原孔隙含水层层间水力联系研究

山东省汶泗河冲洪积平原轴部第四系厚度较大,孔隙地下水分层分布,由于补给径流条件不同导致其水质差别较大,研究含水层间的水力联系对于水资源管理及优质地下水可持续开发利用等具有十分重要的意义。采用群孔抽水试验方法研究苑庄水源地浅层和深层孔隙水之间的水力联系。群孔抽水后6眼抽水井水质指标整体高于抽水前,附近有串层水井的抽水井增加最大,4项指标平均升高1.07倍。抽水试验期间深层观测孔水位变化与抽水井相一致;浅层观测孔水位除有串层的孔稍有下降趋势外,其它孔均呈现自然波动状态。附近有串层水井的抽水井抽水量中浅层孔隙水的补给量比例比其它抽水井要高4倍。抽水前后水质、抽水期间水位动态变化规律、抽水井抽水量中浅层孔隙水补给量占比均表明深层孔隙水在开发利用过程中会受浅层孔隙水影响,但是可通过合理止水减弱含水层之间的水力联系。     

孟加拉国巴拉普库利亚煤矿含水层水力联系研究

为进一步查明孟加拉国巴拉普库利亚煤矿水文地质特征及含水层间水力联系,为矿井水害防治提供理论依据,以19组水质化验数据为基础,结合含水层及隔水层空间展布特征、井田构造特征、水位历时曲线、水化学类型、氢氧同位素特征等,综合分析新近系UDT含水层、Ⅵ煤顶板含水层、Ⅵ煤含水层之间的水力联系。结果表明,井田北部LDT隔水层局部缺失,为UDT含水层水向含煤地层补给提供了条件;井田北翼煤层顶板含水层与UDT含水层水位变化规律密切相关,且水位相近,初步证明两者存在水力联系;各含水层水均为HCO₃-Ca·Na·Mg型,均为低矿化度水,进一步证明各含水层间存在水力循环;聚类分析结果表明各含水层水质存在一定关联度,推演含水层间水力联系程度;氢(δD)氧(δ18O)同位素特征点分布于全球大气降水线附近,表明大气降水是各含水层共同的补给水源。研究成果可以指导孟加拉国巴拉普库利亚煤矿Ⅵ煤层开采时水害防治方向。      

鹤岗矿区新陆煤矿主要含水层之间水力联系分析

鹤岗矿区新陆煤矿主要充水含水层为白垩系石头庙子组砾岩裂隙含水层与石头河子组砂岩裂隙含水层,石头庙子组含水层富水性强,石头河子组含水层距离可采煤层较近,两含水层均为煤层顶板直接充水含水层,若发生水力联系,将会严重威胁煤矿开采。在分析矿井水文地质条件的基础上,从水化学特征、水位、隔水层、断层影响区地面瞬变电磁特征等方面对两含水层特征进行综合对比分析,得出了两含水层一般区域水力联系弱,在断层影响区域水力联系相对强的规律,为煤矿防治水工作提供了重要参考依据。     

上海市第三、四承压含水层间存在直接水力联系地段

以往上海地区地质、水文地质有关报告和文章都以为上海地区第三、四承压含水砂层间的隔水粘性土层(顶板一般埋深为140米左右)层位稳定,分布普遍,隔水性能良好。第三、四承压含水层无垂向直接水力联系。这就在一定程度上,简化了水文地质条件和相应的地下水资源计算、水化学评价等方面的工作。     

基于巴拉素井田多孔抽水试验的含水层特征及水力联系研究

抽水试验是获取地下水含水层水文地质参数的有效手段之一。为了准确掌握各含水层特征及水力联系,以巴拉素井田为例,通过抽水试验、理论分析、水质化验等方法对井田先期开采地段内开采煤层富水情况、各主要含水层水文地质特征及其水力联系等进行研究。结果表明:矿井未来开采的2、3、8号煤的富水性均较弱;主要含水层中,除第四系含水层富水性中～强、白垩系洛河组含水层富水性中等以外,其它含水层均富水性弱;第四系含水层和白垩系洛河组含水层之间水力联系密切,侏罗系直罗组含水层与白垩系洛河组含水层之间未发现水力联系,侏罗系直罗组含水层与2号煤之间未发现水力联系;3号煤与8号煤之间未发现水力联系。本次抽水试验成果,为矿井未来水文地质及防治矿井水害工作提供了有力的理论依据,同时对周边条件类似矿井具有一定的借鉴价值。     

在多隔层含水层中抽水的水力联系问题

在多隔层含水层中抽水,由于各含水层能通过隔水层,相互进行补给,形成一个相当复杂的水力联系问题。在作了相邻含水层的水头保持常数的假定下,雅各布(Jacob,1946)、汉土什(Hantush,1956)等早已推出了漏含水层、抽水的计算公式。嗣后又由纽曼(Neuman)及威瑟斯庞(Witherspoon,1969)作了更加完善的补充,但对于相邻含水层间,相互补给的问题还很少研究。但选一问题在实际生产工作中却大量存在,这里我们先不考虑隔水层的释水作用,并用一个简易的方法探讨含水层之间的相互影响的关系。     

含水层水力参数的尺度效应研究现状

描述含水层水力特征的主要参数在达西定律和地下水动力学的解释解中都被视为常效，这在实验室或在地下水开采规模不大的局部地段可行，但实际的含水层都为非均质，且人类活动使地下水水质、水量发生了严重变化，改变了地下水驱动力场的物理北学特征和水力特征，就使含水层的水力参数发生了相应的变化。     

基于水力层析法的某煤矿承压含水层叠加放水试验分析

水文地质参数是衡量含水层富水性的重要指标,其空间分布特征的准确推算,对于矿井突水灾害预报与防治具有积极意义。传统放水试验分析方法得到的是等效水文地质参数,不能准确刻画含水层的空间异质性。基于随时间变化的水头数据与水文地质参数的互相关分析,将水力层析法应用在陕西榆林柠条塔煤矿井下承压含水层叠加放水试验数据分析中,获得了研究区水文地质参数的空间分布特征。结果表明,工作面南北富水性差异大,涌水区位于强导水带上;从涌水区往北,导水系数和储水系数整体上逐渐减小;南部导水系数和储水系数均较大,属于富水异常区。研究表明,水力层析法是一种有效的非均质含水层参数识别的新技术,将井下放水视为针对含水层的刺激源,结合水头与水文地质参数的互相关分析,联合多个观测孔的水头响应数据,反演刻画研究区域的主要地质结构特征。在矿井水文地质条件分析中,预先采用水力层析法识别富水异常区域,可以有效降低突水事故风险。     

A hydrogeophysical model of the relationship between geoelectric and hydraulic parameters of anisotropic aquifers

An electrical resistivity method has been used to determine aquifer parameters in the Ganga-Yamuna interfluve in northern India. An existing relationship between the geoelectrical and hydraulic parameters has been modified for the case of an anisotropic aquifer. The hydrogeological framework in the upper part of the Ganga-Yamuna interfluve is evaluated by using existing relationships between hydraulic parameters and geoelectrical parameters for alluvial aquifers. On the basis of aquifer geometry, the area has been divided into two hydraulic units: the western Yamuna flood plain and the Ganga flood plain towards the east. The resistivity data collected in parts of the study area are first interpreted in terms of true resistivity and thicknesses of subsurface layers. The electrical parameters (resistivity and thicknesses) are subsequently correlated with the available pumping test data. Distinct correlations between transmissivity and modified transverse resistance are obtained for the two hydraulic units. A four-parameter model consisting of hydraulic conductivity, modified longitudinal resistivity, modified transverse resistance and hydraulic anisotropy is presented for the anisotropic aquifer underlain by conductive fine grained sediments. The model has been validated at a number of locations, where aquifer parameters are known from pumping test data.     

Use of geochemical modeling to evaluate the hydraulic connection of aquifers: a case study from Chianan Plain, Taiwan

Aquifers are generally composed of highly permeable layers that can conduct a considerable amount of groundwater. Traditionally, aquifer units are correlated through the concept of lithostratigraphy. For low-permeable aquifers, it is difficult to define the spatial distribution of hydrogeological units, and this study attempts to use geochemical modeling to identify the groundwater flow paths in an area of Taiwan. Multiple geochemical analyses, including groundwater chemistry; stable isotopic compositions of hydrogen, oxygen and carbon; and radiocarbon contents were performed. Using these parameters as the constraints of geochemical models, the hydraulic connection was examined between pairs of possibly interlinked wells along four selected cross sections, and the conceptual groundwater model was accordingly established. The resultant model suggests that the hydraulic connection between aquifers should be correlated with the concept of chronological stratigraphy, especially for low-permeable, unconsolidated aquifers. Using Darcy’s law, the hydraulic conductivities of the fine-sand aquifers were estimated to be between 3.14 × 10⁻⁵ and 1.80 × 10⁻⁴ m/s, which are roughly one order of magnitude higher than those derived by in situ pumping tests. The substantial extraction of groundwater over a long period in the studied area could accelerate groundwater flow, leading to an overestimation of the aquifer permeability.

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Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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Résumé En règle générale, les aquifères sont constitués de couches très perméables capables de conduire des quantités d’eau considérables. Les unités aquifères sont traditionnellement corrélées d’un point de vue lithostratigraphique. Dans le cas des aquifères à faible perméabilité, il s’avère difficile de définir une distribution spatiale des unités hydrogéologiques, et cette étude tente d’utiliser la modélisation géochimique pour identifier les cheminements des eaux souterraines dans un secteur de Taiwan. Plusieurs analyses géochimiques ont été réalisées ; elles incluent la chimie des eaux souterraines, les isotopes stables de l’hydrogène, de l’oxygène et du carbone et l’abondance en carbone 14. En utilisant ces paramètres comme contraintes pour les modèles géochimiques, les liaisons hydrauliques entre les puits potentiellement interconnectés ont été étudiées deux par deux, le long de quatre coupes présélectionnées, et le modèle conceptuel a été établi en conséquence. Ce modèle résultant suggère que les connexions hydrauliques inter-aquifères devraient être corrélées avec les concepts stratigraphiques, surtout pour les aquifères non consolidés à faible perméabilité. Les perméabilités dans les aquifères de sables fins ont été estimées par la loi de Darcy entre 3.14 × 10⁻⁵ et 1.80 × 10⁻⁴ m/s, soit environ un ordre de grandeur au-dessus de celles issues des tests de pompage sur site. L’exploitation substantielle des eaux souterraines sur une longue période dans la zone d’étude peut accélérer les écoulements souterrains, menant à une surestimation de la perméabilité de l’aquifère.

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Resumen Los acuíferos están generalmente compuestos de capas muy permeables que pueden conducir una cantidad considerable de agua subterránea. Tradicionalmente, se ponen en correlación las unidades acuíferas a través del concepto de litoestratigrafía. Para los acuíferos de baja-permeabilidad, es difícil de definir la distribución espacial de unidades hidrogeológicas y este estudio intenta usar modelamiento geoquímico para identificar las direcciones del flujo de agua subterránea en un área de Taiwán. Se realizó el análisis geoquímico múltiple, incluyendo la química del agua subterránea, la composición de isótopos estables de hidrógeno, oxígeno y carbono, y el contenido de radiocarbono. Usando estos parámetros como limitantes de modelos geoquímicos, la conexión hidráulica se examinó entre pares de pozos posiblemente interrelacionados, a lo largo de cuatro cortes transversales seleccionados y de acuerdo con esto se estableció el modelo conceptual del agua subterránea. El modelo resultante sugiere que la conexión hidráulica entre los acuíferos deba interrelacionarse con el concepto de estratigrafía cronológica, sobre todo para los acuíferos sin consolidar de baja permeabilidad. Usando la ley de Darcy, se estimaron las conductividades hidráulicas de los acuíferos de arena fina obteniendo valores entre 3.14 × 10⁻⁵ y 1.80 × 10⁻⁴ m/s, las cuales son aproximadamente un orden de magnitud mayor, que aquéllos obtenidos in situ por las pruebas de bombeo. La extracción considerable de agua subterránea durante un periodo largo en el área estudiada, podría acelerar el flujo de agua subterránea, llevando a una sobrestimación de la permeabilidad en los acuíferos.

     

Field evidence of hydraulic connections between bedrock aquifers and overlying granular aquifers: examples from the Grenville Province of the Canadian Shield

Field evidence of hydraulic connections between a bedrock aquifer and an overlying granular aquifer in the Canadian Shield (Grenville Province) is presented. This issue is rarely considered and investigated despite its important hydraulic and chemical consequences and its widespread occurrence worldwide. The methodology employed is based on complementary field tests conducted at specific experimental sites instrumented both in the rock and in the overlying deposits. One of the bedrock sites revealed a natural hydraulic connection with the overlying granular aquifer caused by the weathered surface of the uppermost bedrock. Another site revealed an artificial hydraulic connection between the bedrock and the granular aquifer created by an improperly sealed casing. A regional study showed that hydraulic connections yield an erroneous interpretation of the true hydraulic properties of the tested aquifer. The detection of hydraulic connections is therefore essential to properly define well-capture areas and contamination conditions. It is recommended to practitioners that pumping tests be performed as well as hydrochemical comparisons of each existing aquifer unit. Falling-head permeability tests are also helpful in verifying the quality of the seal at the bedrock–casing contact. More effective procedural controls and better well-construction practices are necessary to reduce the risks of cross-contamination induced by defective seals.     

A numerical investigation to illustrate the consequences of hydraulic connections between granular and fractured-rock aquifers

Natural or artificial hydraulic connections between a granular aquifer in contact with a fractured-rock aquifer can have significant physical and chemical impacts at both a local and a regional scale. In this study, numerical simulations are conducted in order to illustrate the hydrogeological consequences of such hydraulic relationships. The numerical investigation, based on a conceptual model, focuses on the effects of the hydraulic connections when conducting a pumping test in a well that is set into a granular confined aquifer overlying a fractured-rock aquifer which presents a few fractures directly connected to the granular aquifer. It is illustrated that when interpreting the pumping test with the conventional methods consisting of plotting the drawdown versus time, a bias is introduced on the estimation of the transmissivity of the granular aquifer due to groundwater flowing from the fractured-rock aquifer via connecting fractures. However, it is underlined that plotting drawdown log-derivative versus time helps to diagnose the existence of these hydraulic relationships and therefore avoids committing a bias on the transmissivity estimation of the granular aquifer. Numerical simulation results also illustrate that hydraulic connections between the two aquifers can have significant impacts on the hydrogeochemical signature of the granular aquifer under investigation.     

Evaluation of the hydraulic conductivity of aquifers with piles

Distributed piles are often installed in the foundation pit in sandy soil before dewatering. Hydraulic conductivity should be estimated considering the block effect of piles on groundwater seepage. Research shows that the effective medium theory (EMT) could be used to calculate the equivalent hydraulic conductivity (k _eq) of a heterogeneous medium with other material inclusions. In order to verify the applicability of EMT in an aquifer with piles, an experimental investigation is conducted. In this experiment, a sandy soil is considered as an aquifer and polyvinylchloride pipes are adopted as piles. Piles are distributed in rectangular and triangular layouts. The relationship between k _eq of the aquifer and the volume replacement ratio is plotted for these two layouts. The results indicate that EMT could well predict k _eq for the cases with the rectangular layout; however, for triangular layouts, the prediction becomes poor. To provide a better prediction of k _eq of the aquifer with piles distributed in a triangular layout, a modified EMT (MEMT) is proposed, in which a correction factor is adopted considering different layouts of piles. The MEMT can provide better k _eq predictions for an aquifer with piles in the triangular layout pattern than those obtained using the EMT.     

济南市区泉水与东、西郊岩溶水水力联系研究

为查明济南市区泉水与西郊、东郊岩溶水的水力联系,从地层结构、水动力场角度,结合抽水试验、示踪试验和水化学分析等方法研究泉水与岩溶水之间的关系。结果表明,济南市区和西郊之间的刘长山—郎茂山—万灵山一带存在地下水径流通道。刘长山北侧槐苑广场—九中—十四中一带,在埋深350 m处揭露连续的岩溶含水地层,并存在垂向径流通道,市区泉水和西郊岩溶水通过刘长山北侧侵入岩体接触带以下的三山子组含水层连通。市区与东郊之间的燕翅山—七里河一带受舌状侵入岩体的影响,两侧地下水流场存在差异,但山东大学洪楼校区以北埋深485 m处揭露连续的岩溶含水地层,市区泉水和东郊岩溶水可通过侵入岩体接触带以下的三山子组含水层连通。水化学分析结果表明市区泉水与西郊、东郊岩溶水水化学类型一致,具有相同的演化环境。     

Efficient upscaling of hydraulic conductivity in heterogeneous alluvial aquifers

An efficient method to upscale hydraulic conductivity (K) from detailed three-dimensional geostatistical models of hydrofacies heterogeneity to a coarser model grid is presented. Geologic heterogeneity of an alluvial fan system was characterized using transition-probability-based geostatistical simulations of hydrofacies distributions. For comparison of different hydrofacies architecture, two alternative models with different hydrofacies structures and geometries and a multi-Gaussian model, all with the same mean and variance in K, were created. Upscaling was performed on five realizations of each of the geostatistical models using the arithmetic and harmonic means of the K-values within vertical grid columns. The effects of upscaling on model domain equivalent K were investigated by means of steady-state flow simulations. A logarithmic increase in model domain equivalent K with increasing upscaling, was found for all fields. The shape of that upscaling function depended on the structure and geometry of the hydrofacies bodies. For different realizations of one geostatistical model, however, the upscaling function was the same. From the upscaling function a factor could be calculated to correct the upscaled K-fields for the local effects of upscaling.     

基于损伤力学分析的水力压裂三维裂缝形态研究

水力压裂三维裂缝形态及延伸的预测是评价水力压裂效果的主要因素,采用了损伤力学与断裂力学相结合的方法,描述了裂缝表面岩体的力学行为,建立了裂缝面上的损伤判据与损伤演化方程。根据岩石力学与渗流力学,采用有限元方法建立了低渗透储层岩体的流固-损伤耦合方程,并采用Newton-Raphson与线性搜索相结合的方法进行求解,获得了低渗透油层水力压裂三维裂缝的动态扩展过程及最终形态,揭示其力学本质。通过算例验证了理论及计算方法的正确性。在此基础上,分析了影响裂缝扩展的主要因素,其结果可为水力压裂设计提供较为可靠和准确的预测手段,以提高油层水力压裂措施的成功率