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通过对一个滨海多层含水层系统的考察,该含水层系统由上、下弱透水层和介于中间的承压含水层组成,海底露头处被淤泥层覆盖.建立了描述该系统中地下水水头随潮汐波动的数学模型,并得到其解析解.该解析解与六个基本参数有关,分别是承压含水层的海潮传播参数,淤泥层的无量纲透水系数,上下弱透层与承压含水层贮水率的比率 (无量纲)和上下弱透层的无量纲越流.当这些参数取某些特殊值时,我们的解便化简为前人考虑的几种简单情形对应的解.分析表明,承压含水层中地下水水头波幅是上、下弱透水层贮水率和越流系数的减函数,是淤泥层相对透水系数的增函数;波动相位(时滞)是上、下弱透水层贮水率和越流系数的增函数,是淤泥层相对透水系数的减函数. 相似文献
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为求取含水层水文地质参数,常用的试验方法是抽水试验。在进行抽水试验时,经常有越流现象,计算时一般采用越流模型计算。越流模型假定非抽水含水层的水位恒定不变,但在实际抽水过程中,抽水含水层和非抽水含水层间通过越流相互影响、相互作用。如果只考虑抽水含水层的水位变化而不考虑非抽水含水层的水位变化,会导致计算的水文地质参数不准确。实际工作中,有时会在非抽水含水层中布置一口观测井来观测抽水含水层抽水时对非抽水含水层的影响。如果采用多层含水层系统模型的方法,即可利用各含水层观测井中的数据计算出每个含水层和相关弱透水层的水文地质参数,提高参数计算精度、节省资金和工作量。 相似文献
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《岩土力学》2017,(5):1359-1364
弱透水层是含水层系统的重要组成部分,要准确计算弱透水层释水量和变形量需事先确定弱透水层的渗透系数和贮水率值。基于一维含水层系统概念模型,在相邻含水层降深随时间线性增大的边界条件下,推得了无量纲形式的弱透水层降深解析解,分析了弱透水层中滞后降深消散规律。根据水量均衡方程得到了弱透水层累计压缩变形量随时间变化的标准曲线,并提出了一种配线法用以确定弱透水层的渗透系数和贮水率,该配线法能够反映弱透水层释水变形过程的滞后性。以上海含水层系统为例,运用配线法确定了f_(10-7)分层标处第2弱透水层的渗透系数为4.26×10~(-10)m/s,贮水率为2.22×10~(-4)m~(-1)。对于具有长序列变形和水位观测资料的含水层系统,该方法具有一定的适用性。 相似文献
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应用沉降和水位数据计算上海地区弱透水层的参数 总被引：3，自引：0，他引：3
弱透水层参数的确定是准三维或三维地下水流数学模型应用时的难点,而应力-应变图解法是一种估计弱透水层参数的有效方法。在介绍该法的基本原理之后,结合上海沉降和水位观测资料,求出了上海地区弱透水层的弹性贮水率、非弹性贮水率和垂向渗透系数,为上海地面沉降的数值模拟提供了较好的初始参数值。对于弱透水层,抽水试验的方法是不可取的,如果又没有条件取土样作室内试验时,若有沉降资料和相应的水位资料,则应力-应变图解法是确定近似参数值的一种比较好的方法。 相似文献
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滨海地区社会与经济的发展引发了各种各样的水文地质问题, 因此对滨海地区的水文地质条件, 尤其是地下水与海水之间的水力联系的研究尤为重要.本文考察了海底露头处具有淤泥层的滨海含水层系统中由海潮引起的水头波动.该系统由潜水含水层、承压含水层和介于其间的弱透水层构成.建立了该系统的数学模型, 得到了该模型的解析解.该解析解包含2个无量纲参数: 弱透水层的相对越流系数和淤泥层的相对透水系数.解析解表明, 淤泥层使各处的水头波幅被缩小了一个常数倍(波幅缩减因子), 并使各处的波动相位产生了一个不超过45°的正位移常数(时滞).该时滞对半日潮不超过1.5h, 对全日潮不超过3h.波幅缩减因子和正位移常数只与弱透水层的相对越流系数和淤泥层的相对透水系数有关.当这两个无量纲参数取某些特殊值时, 本次研究的解和前人考虑的几种较简单情形所对应的解一致.承压含水层中水头波幅随着淤泥层的相对透水系数的递增而严格递增, 随弱透水层的相对越流系数的递增而严格递减; 波动相位随着这2个无量纲参数的递增均严格递减.分析表明弱透水层的越流和淤泥层的存在均对承压含水层水头波动有显著影响. 相似文献
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刘诚明 《水文地质工程地质》1985,(6)
方法原理 不同类型的越流补给含水层定流量抽水完整井的非稳定流理论解,具有不同的形式。但用定u值法求解时其方法原理是类同的。本文仅介绍考虑弱透水层贮存水的释放的越补含水层参数的计算方法。 相似文献
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弱透水层储存的地下水是地下水资源的重要组成部分,弱透水层水文地质参数对地下水资源管理与评价以及地面沉降等具有重要意义。通过室内试验对定降深条件下弱透水层水流运移规律进行了研究,并探讨了弱透水层释水过程中的变形规律和释水规律。试验结果表明,在相邻含水层定降深条件下,弱透水层固结变形滞后于相邻含水层的降深变化,且变形速度逐渐变小并趋于零。基于室内试验,利用配线法求得弱透水层不同应力状态下的水文地质参数,对比分析,大变形和小变形试验中土层的渗透系数变化不大,但贮水率明显变小,土层的固结系数变大。因此,土层的应力历史对土层的渗透系数影响不大,而对贮水率有较大的影响。 相似文献
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伍兆聪 《水文地质工程地质》1979,(3)
众所周知,正确的数学模型是资源评价工作正确进行的必要前提,而有关的计算方法则是探讨模型的手段。随着人们对复杂的渗流机理研究和水文地质条件认识的深化及现代数学技术的发展,有关越流理论的探讨逐步获得进展。继M.S.汉土什和O.E.雅各布之后,S.P.纽曼与威瑟斯庞进一步就相邻含水层水头随抽水层开采发生变化且同时考虑弱透水层弹性储量的越流系统给出了数学模型及理论解。在模型中假设含水层为均质且各向同性、平面无限边界以及允许有一个开采含水层的情况。然而广泛存在非均质各向异性、不规则的有限边界和不同类型边界条件以及两个(或更多)开采层的复杂越流系统。 相似文献
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《岩土力学》2017,(1):61-66
弱透水层是含水层系统的重要组成部分。弱透水层的渗透系数K_v和弹性贮水率值S_(ske)对研究地面沉降及地下水资源评价具有重要的意义。在相邻含水层降深随时间周期性波动的条件下,推得了超固结弱透水层中无量纲形式的降深解析解,并基于该解析解进一步得到了超固结弱透水层累计变形量随时间变化的理论曲线。由于弱透水层的低渗透性,其变形总是滞后于相邻含水层的降深变化。根据弱透水层变形的滞后时间与含水层降深波动半周期的关系,提出了一种用以确定超固结弱透水层垂向渗透系数和弹性贮水率的方法,该方法对于弹性变形的超固结土具有很好的适用性。使用该方法之前,首先要根据分层标和水位资料确定含水层降深的变化周期以及弱透水层变形的滞后时间。应用该方法确定了上海地区f_(10-7)分层标处第2弱透水层的水力参数为K_v=4.12×10~(-10)m/s,S_(ske)=1.07×10~(-4) m~(-1)。经实例计算结果具有一定的可靠性。 相似文献
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一种实验确定弱透水层水文地质参数的原理与方法 总被引：2，自引：2，他引：0
弱透水层是含水层系统的重要组成部分,弱透水层的水文地质参数(如渗透系数、传导系数、贮水率)不仅对预测、评价和控制地面沉降有重要意义,而且对地下水资源开发、评价和计算以及含水层系统污染物运移规律和热能传导规律的研究有着重要的意义。以饱和承压弱透水层柱体为模型,在一侧水头降低某一常量条件下推得了弱透水层单位水平面积的流量公式,给出了基于流量随时间变化的实验资料采用配线法确定弱透水层传导系数、渗透系数和贮水率的具体方法,并结合实验及相关资料进行了参数的确定和验证。这一方法不仅理论严密,而且具有实验装置及实验过程简单、易操作,获取的参数较多,精度高等优点。因此有很好的推广应用价值。 相似文献
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Summary Formulation and case studies of a three dimensional kinematic model are presented. Thein situ overburden geometry can be simulated accurately and various initiation patterns of blasts can be modelled. The overburden geometry, hole patterns and explosive distribution are all explicit model inputs. Because the effect of explosive properties, rock mass condition and inter-row delay are very difficult to measure in terms of blast performance, these are represented in the model by control parameters which are left for calibration using field data. The output of the model is a three dimensional muckpile shape of any cross section and a contour map of grade distribution within the muckpile. Two case studies are presented which have shown that the model is a valuable tool for optimizing production blasting as well as for controlling grade dilution during blasting. 相似文献
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三维地质建模是“智慧城市”建设的基础内容之一,涉及数百平方公里到数千平方公里的城市级地质范围。由于城市级地质范围跨越地质单元多、地质情况复杂,传统的三维地质建模方法对跨地质单元的地层连线考虑不足,常导致不同地质单元间的地层连线出现错误。针对该问题,提出一种基于地层沉积顺序的统一地层序列方法,进而识别钻孔分层中的缺失和倒转情况,将同一岩性中倒转与正常的情况加以区分,避免建模时的错误连线或插值。通过添加0厚度层,使所有钻孔的地层序列可完全一致,构建各钻孔分层间的对应关系,以降低不同地质单元间的地层连线错误率。通过讨论地层缺失、倒转、重复等特殊情况和实例验证,研究结果能够有效地对城市级三维建模中各种地质情况的连线问题做出明确的判断,减少在跨越地质单元多、地质情况复杂的城市级三维地质建模中的地层连线错误,为“智慧城市”建设提供底层支撑。 相似文献
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深部矿产资源的勘查是战略性矿产资源勘查的一个重要方面。找矿实践证明，化探方法技术在矿产勘查乃至深部找矿中发挥了重要的、不可或缺的作用。找矿工作的不断深入和找矿难度的不断加大，促使化探方法技术不断的发展和完善，在传统方法技术的基础上，研发出了许多新的方法技术。本文从方法论和系统论的角度出发，对现有的找寻深部隐伏矿盲矿的有效化探方法技术进行了系统的归纳和总结，提出了立体地球化学勘查方法技术体系的概念，将立体地球化学勘查方法技术划分为地面地球化学测量方法技术和地下地球化学测量方法技术，建立了深部矿产资源立体地球化学勘查方法技术体系。不同的方法技术有不同的优势和不同的适用条件，实际工作中应当根据不同的勘查阶段，不同的勘查目的和不同的地质地球化学条件选择不同的立体方法技术组合才能发挥出最大效益，取得最大效果。 相似文献
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Using the continuum‐based finite element approach in conjunction with the strength reduction technique, one can easily find out the factor of safety of a slope with rather high precision, but will encounter some obstacles in the accurate location of the corresponding three‐dimensional critical slip surface (CSS). On the basis of the Mohr–Coulomb failure criterion and the stress field in the limit equilibrium state of the slope, it is deduced that the three‐dimensional CSS is the solution of the Cauchy problem of a quasi‐linear partial differential equation (PDE) of first order. By means of the method of characteristics for the problem, the three‐dimensional CSS that may take any shape can be determined without the specification of its geometry. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Piles may be subjected to lateral soil pressures as a result of lateral soil movements from nearby construction‐related activities such as embankment construction or excavation operations. Three‐dimensional finite element analyses have been carried out to investigate the response of a single pile when subjected to lateral soil movements. The pile and the soil were modelled using 20‐node quadrilateral brick elements with reduced integration. For compatibility between the soil–pile interface elements, 27‐node quadrilateral brick elements with reduced integration were used to model the soil around the pile adjacent to the soil–pile interface. A Mohr–Coulomb elastic–plastic constitutive model with large‐strain mode was assumed for the soil. The analyses indicate that the behaviour of the pile was significantly influenced by the pile flexibility, the magnitude of soil movement, the pile head boundary conditions, the shape of the soil movement profile and the thickness of the moving soil mass. Reasonable agreement is found between some existing published solutions and those developed herein. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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In a series of previous works, the plane strain and the axisymmetric cases of the so‐called active trapdoor problem have been modeled by virtue of Litwiniszyn's theory of deep subsidence. However, in reality, there exist trapdoor base geometries—in plan view—which can be very well approximated by an elliptical boundary. Following the elliptical shape of the trapdoor, the contour lines of subsidence also appear to be similar ellipses. In this work, an elliptic model of deep subsidence is presented, the mentioned hypothesis of the self‐similar subsidence contour lines is validated, and finally a simplified model is presented. For completeness of the present three‐dimensional model analysis, a rectangular model is also considered. Results are finally presented and compared with those of plane strain and axisymmetric problems. Some suggestions that have been proposed in previous similar works are also evaluated and compared with the results of the present study. Finally, some estimates are proposed for different trapdoor base geometries. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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This study investigated localized responses, such as circumferential stresses, on corrugation and pipe deflections. Also, this study examined the effect of corrugation geometry on the overall and localized response of corrugated pipes with refined three‐dimensional modeling of the entire soil–pipe interaction system, including corrugation. To investigate the availability of the traditional two‐dimensional method, the results from the three‐dimensional finite element method (FEM) were compared with those from the two‐dimensional FEM. The soil–pipe modeling techniques of this study were verified by comparing the FEM results by Utah State University and analytical results. An artificial neural network (ANN)‐based model to predict vertical deflections of buried corrugated pipes was developed to overcome the shortcomings of existing methods and obtain results that are close to the level of accuracy of FEM results. In order to train an ANN, analyses on a large amount of data were executed with various standardized pipe geometries and burial depths regulated by the Korea Highway Corporation using the two‐dimensional FEM verified in this study. The widely used back propagation algorithm was adopted. The ANN‐based model developed in this study was shown to be an effective tool by comparing the results with test data and sensitivity analyses were executed based on the data from the developed ANN. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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宝昌火山盆地骆驼山地区781矿点位于燕辽构造岩浆活动带西段,是著名燕辽铀成矿带内新近勘查发现的重要矿化区之一。通过对矿区73个钻孔、地形、地层及剖面资料的综合研究,利用Surpac三维软件首次建立了781矿点铀矿化的可视化三维模型,直观地显示了地形、地层、构造、矿体的空间变化特征。地层、构造及矿体三维模型联合研究表明,新识别出的Fa隐伏断裂是最直接的导矿构造和控矿构造,上侏罗统玛尼吐组火山地层为重要含矿层和铀源层。掌握781矿点关键控矿因素,结合矿体空间赋存、分布规律等研究结果,利用Surpac软件在深部定位预测找矿靶区Ⅰ区和Ⅱ区,其具有较精确的空间三维坐标,对深部找矿具有重要指导意义。 相似文献