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Describing how soil properties vary spatially is of particular importance in stochastic analyses of geotechnical problems, because spatial variability has a significant influence on local material and global geotechnical response. In particular, the scale of fluctuation θ is a key parameter in the correlation model used to represent the spatial variability of a site through a random field. It is, therefore, of fundamental importance to accurately estimate θ in order to best model the actual soil heterogeneity. In this paper, two methodologies are investigated to assess their abilities to estimate the vertical and horizontal scales of fluctuation of a particular site using in situ cone penetration test (CPT) data. The first method belongs to the family of more traditional approaches, which are based on best fitting a theoretical correlation model to available CPT data. The second method involves a new strategy which combines information from conditional random fields with the traditional approach. Both methods are applied to a case study involving the estimation of θ at three two-dimensional sections across a site and the results obtained show general agreement between the two methods, suggesting a similar level of accuracy between the new and traditional approaches. However, in order to further assess the relative accuracy of estimates provided by each method, a second numerical analysis is proposed. The results confirm the general consistency observed in the case study calculations, particularly in the vertical direction where a large amount of data are available. Interestingly, for the horizontal direction, where data are typically scarce, some additional improvement in terms of relative error is obtained with the new approach. 相似文献
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文章利用Vulcan和Datamine三维可视化软件建立了虎头崖铅锌多金属矿床矿体的三维实体模型、块体模型及地层三维实体模型;运用地质统计学方法分析了虎头崖矿区67线以东和117线以西矿体的Pb,Zn品位空间变化结构,得出搜索椭球体,实现了虎头崖铅锌多金属矿床矿体、地层形态和铅锌品位变化形态的空间分布展示;结合三维建模结果和铅锌矿体空间变化结构,总结出矿体空间分布规律,并用三维可视化软件对矿体分布规律进行显示,指导隐伏矿体的预测,寻找有利的找矿部位。 相似文献
85.
Rainfall network design using kriging and entropy 总被引:4,自引:0,他引:4
The spatial distribution of rainfall is related to meteorological and topographical factors. An understanding of the weather and topography is required to select the locations of the rain gauge stations in the catchment to obtain the optimum information. In theory, a well‐designed rainfall network can accurately represent and provide the needed information of rainfall in the catchment. However, the available rainfall data are rarely adequate in the mountainous area of Taiwan. In order to provide enough rainfall data to assure the success of water projects, the rainfall network based on the existing rain gauge stations has to be redesigned. A method composed of kriging and entropy that can determine the optimum number and spatial distribution of rain gauge stations in catchments is proposed. Kriging as an interpolator, which performs linear averaging to reconstruct the rainfall over the catchment on the basis of the observed rainfall, is used to compute the spatial variations of rainfall. Thus, the rainfall data at the locations of the candidate rain gauge stations can be reconstructed. The information entropy reveals the rainfall information of the each rain gauge station in the catchment. By calculating the joint entropy and the transmitted information, the candidate rain gauge stations are prioritized. In addition, the saturation of rainfall information can be used to add or remove the rain gauge stations. Thus, the optimum spatial distribution and the minimum number of rain gauge stations in the network can be determined. The catchment of the Shimen Reservoir in Taiwan is used to illustrate the method. The result shows that only seven rain gauge stations are needed to provide the necessary information. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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In the framework of various studies to characterize the aquifer at the groundwater experimental field near Montalto Uffugo, Italy, the present work estimates the spatial distribution of hydraulic conductivity of the unconsolidated deposits that underlie the area, by applying the geostatistical technique of kriging with external drift to electrical-resistivity and hydraulic-conductivity data. The reliability of the estimation method was tested by implementing a model, based on the method of cells, that simulates groundwater flow, with the estimated values of hydraulic conductivity. The results obtained indicate that the estimation method used has an acceptable degree of reliability. 相似文献
89.
Xavier Emery 《Mathematical Geosciences》2008,40(6):671-688
An important aspect in mineral resource evaluation is the reduction of variance when post-processing the grade distributions
defined on the support (volume) of the available data into distributions defined on the support of the proposed selective
mining units. Although the volume-variance relationship is well understood for the estimation of global grade distributions,
it is still an unsolved issue for local estimation studies based on non-parametric geostatistical methods, such as indicator
kriging, for which the support correction is not inherent to the method. To clarify this relationship, the local change of
support problem is examined in the scope of two parametric models (multi-Gaussian and discrete Gaussian models). It is shown
that the variance reduction factor between point and block-support local distributions depends on the block being considered
and is less than the global variance reduction factor. As a consequence, post-processing the local point-support grade distributions
on the basis of the latter systematically understates the importance of the change of support at the local scale and makes
selective mining appear more economically attractive than it really is. In the light of these results, a methodology is proposed
to post-process the local point-support distributions obtained via non-parametric (indicator) methods into block-support distributions.
An application to simulated data indicates that this methodology provides an accurate estimation at the block support when
dealing with diffusion-type random fields. 相似文献
90.
空间软数据及其插值方法研究进展 总被引:7,自引:0,他引:7
由于对地观测技术的迅速发展,空间数据的种类和数量增长迅猛,由空间数据反演得到的各种信息日趋膨胀,这些反演结果中的信息不少以软数据的形式出现。在实际应用中,这些软数据往往与空间插值的目标变量具有一定的相关性,甚至成为控制目标变量空间分布特征的重要因素。然而,由于这些数据通常表示为非数值形式,在计算和处理上存在着一定困难,以致被传统的插值方法所忽视,从而造成信息浪费。近来出现的空间软插值方法是一种利用空间软数据作为辅助信息并以改善插值效果的方法,能够较好的处理并利用软数据所隐含的信息,具有较好的应用发展前景。本文根据空间软数据的特点及其分类,系统综述了空间软插值方法及其应用领域。首先分析了空间数据软硬性质的根本区别,论述了软数据的分类和“硬化”方法,然后介绍空间插值模型中对空间软数据的集成方法和原理,最后对空间软插值方法及其应用研究领域进行了展望。 相似文献