共查询到19条相似文献，搜索用时 399 毫秒
1.
本文根据现有的实验资料说明裘布依假定适用于虚构流网,故所得出的自由水面方程和流量方程也应适用于虚构流网。根据虚构流网概念,获得了完整井或非完整井抽水时流量方程。另一方面,用分析方法获得不完整井抽降不大时的流量方程;利用室内实验资料对方程中的参变数值编成曲线图,并说明此方程的精度亦较一些经验公式为高。 相似文献
2.
在地貭科学1959年第8期上发表了高钟等著“估算含水层厚度H及最大湧水量Qmax的新公式”一文,其內容是从一次抽水降深来估算含水层厚度H及最大湧水量Qmax,它企图以一次抽水資料来确定湧水量公式:Q=aS-βS2中的α、β,然后再利用α/β=4Smax 的关系求出H及Qmax。在代数问题中在任何情况下用一个方程式解含有两个未知数的問題是不可能的。 相似文献
3.
地下水流问题的数字计算机的应用,现虽处于高度发展阶段,但在采用这种数学物理模型时,首先要知道含水层的导水性能。过去利用水位观察资料或抽水试验资料计算水文地质参数的方法,只能适用于简单的含水体系,由于高度复杂的地质体并且间隙水流为非线性的这类参数如何确定还没有解决,如果利用近期发展起来的有限单元法来反求参数是一种理想的选择,特别是与古典的伽勒金法结合起来,既可简化数学处理过程,并有利于解非线性流问题。古典的伽勒金法原来只能适用于简易的分析域,而且要求介质为均一,但与空间离散的有限单元法结合起来,还便于解非均质而且边界不规则的问题。 相似文献
4.
稳定流抽水试验方法执行多年,至今仍为水文地质工作中一种行之有效的方法。但是随着地下水的疏排和开采强度的不断增大,单一的稳定流试验已表现出较多的不适应性。随着非稳定流抽水试验方法的完善和推广,显示了一些稳定流抽水所不具备的优点。笔者认为如何把二者结合起来,进一步应用好非稳流抽水试验方法是当前一个重要问题。下面根据山东一些煤田搞非稳定流抽水试验的体会,作一些讨论,希望能有益于今后的工作。 相似文献
5.
抽水含水层对非抽水含水层水位影响的效应分析 总被引：3，自引：0，他引：3
利用自动水位计记录的抽水试验过程中不同层位含水组之间的动态水位,分析了在抽水试验最初阶段时抽水含水组与非抽水含水组之间的水力联系。研究结果表明:(1)抽水含水层对非抽水含水层存在水位影响效应,在抽水初期,水位影响效应较大;当抽水含水层水位达到稳定或缓慢下降时,水位影响效应随之消失。(2)单位降深水位影响效应显示,上部含水层距离抽水含水层越远,水位影响效应越大;下部含水层距离抽水含水层越远,水位影响效应越小。(3)利用三维地下水流数值模拟方法和应力应变对含水层水位动态影响的原理对水位影响效应机理进行分析,发现水位影响效应与含水层的固体骨架压缩系数(α)、水体积压缩系数(β)、孔隙度(n)和边界控制系数(Cm)等参数有关。 相似文献
6.
自本刊1959年第8期发表了高钟、曹阿昆两同志的“估算含水层厚度H及最大湧水量Qmax的新公式”一文后,我們收到了不少讀者的来信,指出本文的錯誤,并在某些問題上提出了不同的看法。在王以琦、杜欣、熊强和赵桂芳等同志的来信里分別指出:本文把潛水完整井湧水量的鳩布依（J,Dupuit）公式用到非完整并是不正确的;試图用一次抽水試驗来定出湧水量公式Q=αS-βS2中的两个独立参数α、β也是不可能的,从代数观点看来,对于具有五个独立变量的四个方程（Ⅳ）（Ⅱa）（Ⅵ）（Ⅶ）也是不能求得定解的,况且作者在求解Sop的二次方程（Ⅱa）根（Ⅴ）时也有錯誤,因而最后导得的公式也是錯誤的。在这里我們选择刘慈羣、王以琦等同志的来稿刊登出来,以便大家对本問題展开討論。 相似文献
7.
为了揭示在非承压含水层中定水头抽水试验引起的达西-非达西两区流动机理,提出基于有限差分法的地下水定水头抽水井流数值模型。该模型根据抽水的流态特征将含水层分为2个区域：靠近抽水井的有限非达西渗流区域和远离抽水井的半无限达西渗流区域,其中非达西流区域流态的模拟基于Izbash方程实现。通过与COMSOL Multiphysics的有限元数值解进行比较,验证了所提出数值解的可靠性。最后,研究有限非达西流效应对水头和抽水井抽水速率的影响以及井内水头对抽水井抽水速率的影响。研究表明：在抽水试验中非达西区域的影响不可忽略,湍流会分别导致两区流中水头较纯非达西流和纯达西流的水头偏大和偏小,且随抽水时间的增加逐渐变大;通过减小抽水井井内水头或增大非达西系数可提高抽水速率,但该影响会随抽水时间的增加而逐渐减弱;断面流量随径向距离的增大而不断减小,断面流量与径向距离曲线下降速率不断减小,且在转换界面处会出现转折点。该模型为定量研究在非达西流和达西流耦合作用下抽水井附近的井流水头特征提供了一种简洁的方法,并为调查定水头抽水测试期间的抽水速率提供理论依据。 相似文献
8.
朱伟武 《水文地质工程地质》1992,19(2):34-40
在抽水试验过程中,常因突然停电,设备故障等而导致试验间断,此类问题普遍存在,其求参尚无适当的方法和公式可循。本文充分考虑到实际抽水过程与抽水间断的影响,根据势函迭加原理对泰斯型含水层的单孔、多孔、群孔间断性抽水试验的求参问题均进行了研究,推导出相应的一系列公式与求参方法,此类公式具有普遍性理论意义和实用价值,可视为相应的无间断抽水求参公式的拓广形式。 相似文献
9.
为了减少因分层抽水而造成的钻探施工过程中的困难,长期以来水文地质工作者在探讨用混合抽水试验确定含水层水文地质参数的方法。在已有的方法中,多采用稳定流混合抽水试验加做某些辅助工作的办法,以确定含水层水文地质参数。但由于稳定流抽水试验本身在理论上的缺陷,尤其是因为有的方法需要 相似文献
10.
本文从非稳定流理论出发,将稳定流抽水试验概化为包含零流量抽水时段的阶梯式非稳定流抽水试验,分析出井损仅存在于非零流量抽水的时段,据此确定了求参计算拟合的主要目标和井损的计算方法,进而编制了适合于直线边界,边界性质为定水头、隔水、边界不存在或边界无影响三种常见情况的计算程序。并结合实例,反演了水文地质条件,较为准确地计算了水文地质参数、井损及井损与抽水量的关系。 相似文献
11.
地下水的补排主要包括垂向的地面入渗补给、蒸发排泄（蒸发可视为入渗的负值）及侧向的地表水补给、排泄。水文地质学最基本的问题之一——地下水可持续开釆量的评价准则,涉及补给的增量与排泄的减量,因此地下水开采的预测模型必须包含上述两类的补给、排泄因素,否则不能满足要求。然而,经典的Theis不稳定井流模型,即使在傍河抽水,也只有侧边界的补给、排泄作用,而不涉及上边界的地面入渗补给。这样一来,这个解析模型基本上不能够用于预测,而只能在旱季用于井流试验求取含水系统的参数。为此,文章的目标是发展具地面入渗补给的Theis不稳定潜水井流模型。对于潜水流问题,不能再用承压水流的以水头为应变量的方程来建立,应采用第二类线性化方法的势函数来建立潜水流问题。对于既有降雨入渗补给,又有抽水井作用的复杂的水文地质问题所概化数学模型的求解,采取的方法是把它分解成若干个简单的子模型问题求解,然后将其合成为原来复杂数学模型的解。基于质量守恒原理,假定渗流服从Darcy定律并满足Dupuit徦定建立了水流基本微分方程。然后对于两平行河流及一河流平行一隔水边界形成的两类条形区域,具地面均匀稳定入渗补给的井流问题,获得通用水位方程和几类常见的特定条件水位方程及其流量方程。此外,提出并采用“边界对边界的反映法”用以求解一河流平行一隔水边界条形区域的同一问题,减少了许多推导过程。最后,作为上述理论成果的初步应用,也是一个重要的应用,即在河水水质不能满足要求的河流附近,设有一口抽水井,计算该抽水井在不汲取河水的前提下的临界流量方程,获得具重要意义的结构简洁的关系式。该方程也可以用于滨海区的抽水井,在不发生海水入侵前提下的临界抽水流量计算。给出了上述条件不稳定井流过程某时刻的地下水流网图,其流网与文献中常见的傍河井流的流网相比,具显明的特征。 相似文献
12.
The flow rate to fully screened, partially penetrating wells in an unconfined aquifer is numerically simulated using MODFLOW 2000, taking into account the flow from the seepage face and decrease in saturated thickness of the aquifer towards the well. A simple three-step method is developed to find the top of the seepage face and hence the seepage-face length. The method is verified by comparing it with the results of previous predictive methods. The results show that the component of flow through the seepage face can supply a major portion of the total pumping rate. Variations in flow rate as a function of the penetration degree, elevation of the water level in the well and the distance to the far constant head boundary are investigated and expressed in terms of dimensionless curves and equations. These curves and equations can be used to design the degree of penetration for which the allowable steady pumping rate is attained for a given elevation of water level in the well. The designed degree of penetration or flow rate will assure the sustainability of the aquifer storage, and can be used as a management criterion for issuing drilling well permits by groundwater protection authorities. 相似文献
13.
目前对潜水含水层地下水潮汐效应和水文地质参数求解方法的研究相对较少.通过对福建古雷半岛滨海潜水含水层地下水潮汐效应和海水潮汐动态的观测, 运用Fourier频谱分析方法确定了研究区海水潮汐波动方程(波动特征参数), 并以此作为地下水的边界条件, 推导了潜水含水层地下水潮汐效应的波动方程, 利用最小二乘法以地下水水位波动观测值为目标函数对潜水含水层的渗透系数与重力给水度的比值进行了反演识别, 为类似地区水文地质参数的确定提供了借鉴, 也为该区后续地下水中溶质迁移规律的研究奠定了基础. 相似文献
14.
The effects of simplifying hydraulic property layering within an unconfined aquifer and the underlying confining unit were assessed. The hydraulic properties of lithologic units within the unconfined aquifer and confining unit were computed by analyzing the aquifer-test data using radial, axisymmetric two-dimensional (2D) flow. Time-varying recharge to the unconfined aquifer and pumping from the confined Upper Floridan aquifer (USA) were simulated using 3D flow. Conceptual flow models were developed by gradually reducing the number of lithologic units in the unconfined aquifer and confining unit by calculating composite hydraulic properties for the simplified lithologic units. Composite hydraulic properties were calculated using either thickness-weighted averages or inverse modeling using regression-based parameter estimation. No significant residuals were simulated when all lithologic units comprising the unconfined aquifer were simulated as one layer. The largest residuals occurred when the unconfined aquifer and confining unit were aggregated into a single layer (quasi-3D), with residuals over 100% for the leakage rates to the confined aquifer and the heads in the confining unit. Residuals increased with contrasts in vertical hydraulic conductivity between the unconfined aquifer and confining unit. Residuals increased when the constant-head boundary at the bottom of the Upper Floridan aquifer was replaced with a no-flow boundary. 相似文献
15.
Gennaro A. Stefania Marco Rotiroti Letizia Fumagalli Fulvio Simonetto Pietro Capodaglio Chiara Zanotti Tullia Bonomi 《Hydrogeology Journal》2018,26(1):147-162
A groundwater flow model of the Alpine valley aquifer in the Aosta Plain (NW Italy) showed that well pumping can induce river streamflow depletions as a function of well location. Analysis of the water budget showed that ～80% of the water pumped during 2 years by a selected well in the downstream area comes from the baseflow of the main river discharge. Alluvial aquifers hosted in Alpine valleys fall within a particular hydrogeological context where groundwater/surface-water relationships change from upstream to downstream as well as seasonally. A transient groundwater model using MODFLOW2005 and the Streamflow-Routing (SFR2) Package is here presented, aimed at investigating water exchanges between the main regional river (Dora Baltea River, a left-hand tributary of the Po River), its tributaries and the underlying shallow aquifer, which is affected by seasonal oscillations. The three-dimensional distribution of the hydraulic conductivity of the aquifer was obtained by means of a specific coding system within the database TANGRAM. Both head and flux targets were used to perform the model calibration using PEST. Results showed that the fluctuations of the water table play an important role in groundwater/surface-water interconnections. In upstream areas, groundwater is recharged by water leaking through the riverbed and the well abstraction component of the water budget changes as a function of the hydraulic conditions of the aquifer. In downstream areas, groundwater is drained by the river and most of the water pumped by wells comes from the base flow component of the river discharge. 相似文献
16.
文章提出并采用水力坡度分析方法,对潜水回水初始阶段进行了定性-半定量分析,为了解潜水回水过程提供了新的视角。通过分析潜水回水初始时刻的水力坡度,河渠侧的界面被分为2段:河间潜水位之上的铅直段和之下的水平段。水平段上点的水力坡度最大且相等,方向为水平向右;铅直段上点的水力坡度方向趋于铅直向下,越向上水力坡度越小。经过微小时间段Δt后,水力坡度均相应变小,铅直段相邻点间地下水运动发生冲突,水力坡度方向由趋于铅直向下向右偏转。将水力坡度分析方法用于分析潜水井流的过程和特征,水跃的成因可解释为:在相同水力坡度和过水断面面积下,井内大空间水流速度远大于孔隙中的潜水流速度,井内水位急速下降,从而形成水跃;水跃越大,进入井内的流量就越大。 相似文献
17.
Equations of equilibrium (force balance) and flow in multidimensions were coupled in this paper to describe land displacements due to pressure decline in aquifers. A Galerkin finite element model based on these equations was developed. The saturated/unsaturated behaviour and the isotropic/anisotropic properties of permeability and elasticity were considered when the model was formulated. This model was verified by comparing its simulation results with those of known analytical solutions for simplified cases. The simulation of displacements due to pressure decline in unsaturated media was also performed. Those results demonstrated that the choice of boundary ranges for an aquifer with infinite domain may significantly affect the estimated horizontal and vertical displacements. To obtain a good estimation of land displacements, the boundary ranges should be carefully chosen. The displacements occurring in unconfined aquifers are caused by the drop of the water table and the change in body force in the dewatering zone. Simulation results also indicated that the change in body force should be considered once an unconfined aquifer has been pumped. Otherwise, the horizontal and vertical displacements in unconfined aquifers would be overestimated and underestimated, respectively. The behaviour of land displacements due to pumping was shown to be affected by changes in the total stresses in aquifers. 相似文献
18.
工程建设中当距离抽水井r=rb处水位基本没有变化或不受抽水影响时,或当此处存在止水帷幕时,含水层系统视为侧向有限延伸,rb为有限半径。为此,构建更加符合工程实际的侧向有限延伸的典型弱透水层-承压水层系统中非完整井非稳定流计算模型,同时考虑井径和井储效应的影响,应用Laplace变换和分离变量法得到了水位降深在拉氏空间下的解析解,并应用拉氏数值逆变换Stehfest法得到真实空间下的水位降深。新建立的解析解可以进一步退化为诸多已有解,并进一步将其与已知解和有限元数值解进行对比,验证了所得解的正确性和可靠性。基于新建解重点分析了侧向边界和井的完整性对承压水层水位降深的影响。结果表明:含水层系统的侧向有限边界仅对抽水后期的水位降深影响明显,含水层系统侧向无限延伸情况下的水位降深要大于情形1(在r=rb处为定水头边界)且明显小于情形2(在r=rb处为不透水边界)下的水位降深,rb越小,两者之间的误差越大;抽水井的完整性对整个抽水期间不同情形下的水位降深均有明显的影响,承压含水层顶板处的水位降深随着抽水井滤管的长度和埋深的增加而减小。 相似文献
19.
An approach is presented for the analysis of the unconfined steady-state seepage through homogeneous trapezoidal dams based on a bijective mapping between the flow domain, having an unknown shape, and a fixed triangular domain. It is shown that the geometrically non-linear unconfined analysis is equivalent to the problem of determining the unknown distribution of permeability, within a triangular domain with known shape, that satisfies the set of transformed boundary conditions. The flow problem in the triangular domain is solved through a finite-element technique analogous to that adopted for confined analyses and, on the basis of this solution, the shape of the free surface in the physical space is evaluated. The proposed approach is applied to the determination of the influence of the water levels in the upper and lower reservoirs on the elevation of the free surface seepage point. 相似文献