中子活化分析在公路交通燧洞水文地质调查中的应用   总被引：1，自引：0，他引：1  

侯新生  贾疏源  王永利  虞修竞  唐光洁  于静 《物探与化探》2002,26(4):293-295

利用中子活化测试结果 ,对岩石及泉水干涸残余物中常量及微量元素的进行分析对比 ,以了解深层岩体有关的地质与水文地质信息  相似文献   

长清井田环境水文地质特征分析与评价     

吴恩江 《中国煤田地质》2001,13(4):45-46

在分析井田环境水文地质特征的基础上，利用浅层地下水的分析测试资料，依据水环境污染综合评价指数方法对浅层地下水环境质量的现状进行了评价。简要阐述了矿区开发对地下水资源可能造成的影响，矿区开发后地下水环境的一些变化趋势及初步预防措施，为将来矿井设计、建设和生产过程中浅层地下水环境的保护和利用提供了参考资料。  相似文献   

洞庭湖区的区域环境水文地质现状   总被引：13，自引：0，他引：13  

涂继武 《湖南地质》2001,20(3):203-206

据综合污染指数计算分析，洞庭湖区域浅层地下水分为重度，中度、轻度和非污染4个等级。区域环境水文地质恶化的主要原因是工农业生产，血吸虫防治和居民生活所造成的人为污染，应重点从保护自然环境，合理开采地下水、科学使用农药化肥，改革工业结构，健全环保法规等方面进行预防和治理。  相似文献   

GPS定位中对流层折射估计研究   总被引：34，自引：6，他引：34  

葛茂荣  刘经南 《测绘学报》1996,25(4):285-291

本文首先讨论了ＧＰＳ相对定位中的对流层折射２估计的单参数方法，多参数方法，分估线性方法和随机过程方法。论证了其它方法都是随机过程方法的近似。为了用随机过程模拟对流折射，建立了一种最小二乘递推算法。在此基础上，在ＧＡＭＩＴ软件中统一实现了以各种对流层折射估计方法。最后给出并分析了不同方法所获得的结果。  相似文献   

Estimation of the transfer function by autoregressive deconvolution techniques—An application to time series analysis     

Y. S. Kang  J. J. Royer  Cl. Chambon  L. Demassieux 《Mathematical Geology》1992,24(5):479-498

The transfer function of time-dependent models is classically inferred by the ordinary least squares (OLS) techniques. This OLS technique assumes independence of the residuals with time. However, in practical cases, this hypothesis is often not justified producing inefficient estimation of the transfer function. When the residuals constitute an autoregressive process, we propose to apply the Box-Jenkins' method to model the residuals, and to modify in a simple manner the primary convolution equation. Then, a multivariate regression technique is used to infer the transfer function of the new equation producing time-independent residuals. This three-step autoregressive deconvolution technique is particularly efficient for time series analysis. The reconstitution and the forecasting of real data are improved efficiently. Theoretically, the proposed method can be extended to the convolution equations for which the residuals follow a moving average or an autoregressive-moving average process, but the mathematical formulation is no longer direct and explicit. For this general case, we propose to approximate the moving average or the autoregressive-moving average process by an autoregressive process of sufficient order, and then the transfer function. Two case studies in hydrogeology will be used to illustrate the procedure.  相似文献   

地下水对工程和环境的作用   总被引：5，自引：2，他引：5  

张咸恭 《工程地质学报》1993,1(1):1-6

地下水对上程建设和地质环境的作用与影响日趋显著,人们认识日益深化。实践表明,这类问题不完伞是纯水文地质问题。实质上,它是介乎于水文地质与工程地质之间,暂定名为工程水文地质学。专门进行在工程建设和环境地质中由于地下水作用而产生的各类工程地质问题或水文地质问题。为充分阐明问题,本文从水与岩土相互作用、基坑排水与潜蚀流沙、地基沉降与黄土湿陷、道路冻害与隧道涌水、矿抗突水与竖井破坏、坝基渗漏与稳定、坝基抗滑稳定以及与地下水有关的地质灾害问题等方面,进行了举例阐述,初步论证了重要性、问题和某些实质。目的在于,向人们揭示一个值得研究的方向,并给予充分的重视。  相似文献   

中国西部及邻区的地壳三维速度结构     

单新建  冯德益 《内陆地震》1993,7(2):142-150

用网格频散反演技术计算了155条瑞利面波混合频散数据,将中国大陆分为目前最小分格2°×2°,得到了中国西部及邻区深至80km地壳和上地幔顶部的三维剪切波SV速度结构。结果表明:(1)天山褶皱系地壳平均厚度为54km,上地壳平均速度为3.3km/s,下壳平均速度3.93km/s,上地幔盖层平均速度为4.64km/s,都偏大。北天山壳厚比天山薄,壳和上地幔盖层下均有低速层。(2)塔里木盆地中部地壳厚46km,到其边缘的昆仑山、天山地带壳厚增加到52～55km。壳内无低速层,壳平均速度很低,为3.49km/s,地表有9km的沉积层。(3)青藏高原莫霍面呈凹形,平均壳厚为67km,平均壳速度为3.58km/s。东西端存在壳内低速层,埋深为15～35km。(4)南北带为构造复杂的区域,莫霍面深度具有东高西低,南北两端高、中间低的特点,带内普遍存在壳内低速层。南北带从群速度、速度、莫霍面等深线都可看到明显的横向差异。(5)准噶尔盆地地壳厚47km,无壳内低速层,中地壳不明显。该区呈稳定的大陆壳结构。(6)柴达木盆地在正常速度的中壳顶部有一高速夹层,速度为3.72km/s,厚10km,上顶部埋深14km。  相似文献   

Stochastic perturbation analysis of groundwater flow. Spatially variable soils,semi-infinite domains and large fluctuations     

G. Christakos  C. T. Miller  D. Oliver 《Stochastic Environmental Research and Risk Assessment (SERRA)》1993,7(3):213-239

As is well known, a complete stochastic solution of the stochastic differential equation governing saturated groundwater flow leads to an infinite hierarchy of equations in terms of higher-order moments. Perturbation techniques are commonly used to close this hierarchy, using power-series expansions. These methods are applied by truncating the series after a finite number of terms, and products of random gradients of conductivity and head potential are neglected. Uncertainty regarding the number or terms required to yield a sufficiently accurate result is a significant drawback with the application of power series-based perturbation methods for such problems. Low-order series truncation may be incapable of representing fundamental characteristics of flow and can lead to physically unreasonable and inaccurate solutions of the stochastic flow equation. To support this argument, one-dimensional, steady-state, saturated groundwater flow is examined, for the case of a spatially distributed hydraulic conductivity field. An ordinary power-series perturbation method is used to approximate the mean head, using second-order statistics to characterize the conductivity field. Then an interactive perturbation approach is introduced, which yields improved results compared to low-order, power-series perturbation methods for situations where strong interactions exist between terms in such approximations. The interactive perturbation concept is further developed using Feynman-type diagrams and graph theory, which reduce the original stochastic flow problem to a closed set of equations for the mean and the covariance functions. Both theoretical and practical advantages of diagrammatic solutions are discussed; these include the study of bounded domains and large fluctuations.  相似文献   

Conditioning mean steady state flow on hydraulic head and conductivity through geostatistical inversion   总被引：5，自引：2，他引：3  

A. F.?Hernandez  S. P.?NeumanEmail author  A.?Guadagnini  J.?Carrera 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(5):329-338

Nonlocal moment equations allow one to render deterministically optimum predictions of flow in randomly heterogeneous media and to assess predictive uncertainty conditional on measured values of medium properties. We present a geostatistical inverse algorithm for steady-state flow that makes it possible to further condition such predictions and assessments on measured values of hydraulic head (and/or flux). Our algorithm is based on recursive finite-element approximations of exact first and second conditional moment equations. Hydraulic conductivity is parameterized via universal kriging based on unknown values at pilot points and (optionally) measured values at other discrete locations. Optimum unbiased inverse estimates of natural log hydraulic conductivity, head and flux are obtained by minimizing a residual criterion using the Levenberg-Marquardt algorithm. We illustrate the method for superimposed mean uniform and convergent flows in a bounded two-dimensional domain. Our examples illustrate how conductivity and head data act separately or jointly to reduce parameter estimation errors and model predictive uncertainty.This work is supported in part by NSF/ITR Grant EAR-0110289. The first author was additionally supported by scholarships from CONACYT and Instituto de Investigaciones Electricas of Mexico. Additional support was provided by the European Commission under Contract EVK1-CT-1999-00041 (W-SAHaRA-Stochastic Analysis of Well Head Protection and Risk Assessment).  相似文献   

Another look at the conceptual fundamentals of porous media upscaling     

G.?ChristakosEmail author 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(5):276-290

We suggest a critical look at the epistemic foundations of the porous media upscaling problem that focuses on conceptual processes at work and not merely on form manipulations. We explore the way in which critical aspects of scientific methodology make their appearance in the upscaling context, thus generating useful effective parameters in practice. The fons et origo of our approach is a conceptual blending of knowledge states that requires the revision of the traditional method of scientific argument underlying most upscaling techniques. By contrast to previous techniques, the scientific reasoning of the proposed upscaling approach is based on a stochastic model that involves teleologic solutions and stochastic logic integration principles. The syllogistic form of the approach has important advantages over the traditional reasoning scheme of porous media upscaling, such as: it allows the rigorous derivation of the joint probability distributions of hydraulic gradients and conductivities across space; it imposes no restriction on the functional form of the effective parameters or the shape of the probability laws governing the random media (non-Gaussian distributions, multiple-point statistics and non-linear models are automatically incorporated); it relies on sound methodological principles rather than being ad hoc; and it offers the rational means for integrating the multifarious core knowledge bases and uncertain site-specific information sources about the subsurface system. Previous upscaling results are derived as special cases of the proposed upscaling approach under limited conditions of porous media flow, a fact that further demonstrates the generalization power of the approach. Our hope is that looking at the upscaling problem in this novel way will direct further attention to the methodological exploration of the problem at the length and the detail that it deserves.I would like to thank Drs. A. Kolovos and D.T. Hristopulos for their valuable comments. The work was supported by grants from the Army Research Office (Grant no. DAAG55–98–1-0289) and the National Institute of Environmental Health Sciences (P42-ES05948 & P30-ES10126).  相似文献