A simplified approach for vulnerability assessment in moderate-to-low seismic hazard regions: application to Grenoble (France)   总被引：3，自引：2，他引：3  

Philippe Guéguen  Clotaire Michel  Laele LeCorre 《Bulletin of Earthquake Engineering》2007,5(3):467-490

Due to the moderate seismic risks in France, the building vulnerability assessment methods developed for high seismic risk countries could not easily be used here because of their cost and the low-risk perception among the public and officials. A light vulnerability assessment method is proposed and tested in Grenoble (France), based on classes and scores provided in the GNDT method but simplified in terms of visual screening and number of structural parameters used. Compared to the RiskUE method, the damage obtained by our approach shows that 90% of buildings have residuals smaller than 0.2, i.e. one grade of the EMS98 damage scale. A large scale survey is devised and conducted among the inhabitants of Grenoble in order to collect the main structural parameters. By comparing the results from the survey to the historical urbanization of Grenoble and to expert surveys performed in two urban districts, the information useful for the light method of vulnerability assessment can be rapidly collected by non-experts reducing substantially the estimate cost. The average damage is then computed using the GNDT formula considering the probable intensities which could be observed in Grenoble (VII and VIII). The average damage reaches 0.4 in the oldest part of Grenoble mainly made of masonry buildings and 0.2 in reinforced concrete suburbs where reinforced concrete predominates. The results are a relative vulnerability assessment that provides useful initial information for the urban zones of Grenoble where the vulnerability is higher. This method can be used to classify the seismic vulnerability in wide seismic-prone regions to a fair degree of accuracy and at low cost.  相似文献   

Multi-scale heterogeneity of soil moisture following snow thawing in Haloxylon ammodendron shrubland     

LI Jun  ZHAO ChenYi  ZHU Hong  WANG Feng  WANG LiJuan  KOU SiYong 《中国科学D辑(英文版)》2007,50(Z1):49-55

Spatial variation of soil moisture after snow thawing in South Gurbantunggut was quantitatively studied using ANOVA and geostatistics at various scales. The results show that the soil moisture heterogeneity varies along with spatial scales. At the shrub individual scale, there is a gradient in soil moisture from shrub-canopied area to canopy margin and to the interspaces between shrubs. At the community scale, soil moisture is highly autocorrelated and the semivariogram is fitted as spherical model, with an 89.6% structural variance and a range of 4.02 m. In addition, Kringing map indicates that the soil moisture distribution pattern after snow thawing is highly consistent with the shrub patch pattern. At the typical inter-dune transect scale, soil moisture presents a pattern of high value at inter-dune depression and low value at dune, and this variation is fitted as Gaussian model with a structural variance of 95.8% and a range of 66.16 m. The range is comparable with the scale of topography zoning, suggesting that the topography pattern controls the pattern of snowmelt at this scale. The evidence indicates that the heterogeneity of soil moisture at various scales is controlled by various land surface processes after snow thawing. For Gurbantunggut Desert, the spatial heterogeneity of snowmelt at various scales is ecologically valuable, because it promotes the utilization efficiency of the snowmelt for the desert vegetation.  相似文献   

3D image-based characterization of fluid displacement in a Berea core     

M. Prodanović  W.B. Lindquist  R.S. Seright 《Advances in water resources》2007

Improved network flow models require the incorporation of increasingly accurate geometrical characterization of the microscale pore structure as well as greater information on fluid–fluid interaction (interfaces) at pore scales. We report on three dimensional (3D) pore scale medium characterization, absolute permeability computations for throat structures, and pore scale residual fluid distribution in a Berea core. X-ray computed microtomography combined with X-ray attenuating dopants is used to obtain 3D images of the pore network and to resolve phase distributions in the pore space.  相似文献   

Dual models of pore spaces     

Roland Glantz  Markus Hilpert 《Advances in water resources》2007

We present a model for pore spaces that consists of two parts related by duality: (1) a decomposition of an open polyhedral pore space into open contractible pore bodies separated by relatively open interfaces and (2) a pore network that is homotopy equivalent to the pore space. The dual model is unique and free of parameters, but it relies on regularity conditions for the pore space. We show how to approximate any pore space by the interior of a polyhedral complex such that the regularity conditions are fulfilled. Thus, we are able to calculate the dual model from synthetic porous media and images of real porous media. The pore bodies are unions of relatively open Delaunay cells with respect to the corners of the pore boundary, and the pore network consists of certain at most two-dimensional (2D) Voronoi cells with respect to the corners of the pore boundary. The pore network describes the neighborhood relations between the pore bodies. In particular, any relatively open 2D Delaunay face f separating two pore bodies has a unique (relatively open) dual network edge. In our model, f is a pore throat only if it is hit by its dual network edge. Thus, as opposed to widespread intuition, any pore throat is convex, and adjacent pore bodies are not necessarily separated by pore throats. Due to the duality between the pore network and the decomposition of the pore space into pore bodies it is straightforward to store the geometrical properties of the pore bodies [pore throats] as attributes of the dual network vertices [edges]. Such an attributed network is used to perform 2D drainage simulations. The results agree very well with those from a pore-morphology based modeling approach performed directly on the digital image of a porous medium. Contractibility of the pore bodies and homotopy equivalence of the pore space and the pore network is proven using discrete Morse theory and the nerve theorem from combinatorial topology.  相似文献   

Suspended sediment load transport in the Mississippi River basin at St. Louis: temporal scaling and nonlinear determinism     

Bellie Sivakumar  Ji Chen 《地球表面变化过程与地形》2007,32(2):269-280

This study investigates the dynamic behavior of suspended sediment load transport at different temporal scales in the Mississippi River basin. Data corresponding to five successively doubled temporal scales (i.e. daily, two‐day, four‐day, eight‐day and 16‐day) from the St. Louis gaging station in Missouri are analyzed. The investigation is focused on identifying possible low‐dimensional deterministic behavior in the suspended sediment load transport dynamics, with an aim towards reduction in model complexity. The correlation dimension method is used to identify low‐dimensional determinism. The suspended sediment load dynamics are represented through phase‐space reconstruction, and the variability is estimated using the (proximity of) reconstructed vectors in the phase space. The results indicate the presence of low‐dimensional determinism in the suspended sediment load series at each of the five temporal scales, with the variables dominantly governing the dynamics in the order of three or four. These results not only suggest the appropriateness of relatively simpler models but also hint at possible scale invariance in the suspended sediment load transport dynamics. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

次天气尺度与中尺度暴雨间相互作用的研究综述     

陈建萍  尹小飞  丁可清 《气象与减灾研究》2002,25(3):14-18

参考了近年来有关次天气尺度与中尺度暴雨间相互作用的文献,主要论述了低空急流与中尺度暴雨、高低空急流耦合与中尺度暴雨之间的关系。指出暴雨的研究主要是使用滤波、数值模拟及诊断分析;暴雨的诊断研究还是集中在垂直速度、水汽通量、辐合辐散等方面,有必要寻找并研究新的指数和物理量。  相似文献   

云顶充满度的特征分析   总被引：1，自引：0，他引：1       下载免费PDF全文

李浩  廖仿玉 《气象科学》2002,22(3):337-342

本文采用GMS－5红外云母，提取了一个描述云顶结构特征的参数一云顶充满度VS。结合地面观测资料，引入了云高参数DTS，得到并分析了参数VS随云高DTS的分布特征，同时还讨论了VS的天气学意义。  相似文献   

基于尺度的GIS空间资料表达模型   总被引：3，自引：2，他引：3  

刘妙龙  吴原华 《测绘学报》2002,31(Z1):81-85

介绍了基于层的GIS空间资料表达方法易于进行空间查询与空间分析处理的优点,针对其引起的地图难以进行扩展与图像显示转换困难的缺点,提出了基于尺度(比例尺)的空间资料表达新方法.在基于尺度的空间资料表达方法中,地图可以由空间对象,区域,尺度视图三级尺度模型表达.对尺度方法下的地图结构,地图组织,指标结构,地图扩展等在理论上作了探讨,提出了基于尺度的方法与已广为使用的基于层的方法的有效集合,将有可能成为地理信息表达研究的最重要研究方向.  相似文献   

裂隙岩体地下水溶质运移的尺度问题   总被引：7，自引：1，他引：7       下载免费PDF全文

王锦国  周志芳 《水科学进展》2002,13(2):239-245

核废料的安全贮存、地下污染的预测控制等目前面临的许多重大问题要求对大尺度裂隙岩体地下水溶质运移问题进行研究,然而裂隙岩体地下水溶质运移问题的尺度效应给这项研究带来了极大的挑战.本文介绍了裂隙岩体地下水溶质运移的多尺度概念模型及其物理和数学模拟方法,并探讨了模拟尺度与观测尺度、预测尺度、裂隙介质尺度之间的关系及尺度效应的分形特征.  相似文献   

区调提速的紧迫性和可行性   总被引：2，自引：0，他引：2       下载免费PDF全文

张洪涛庄育勋  其和日格 陈克强 《中国地质》2002,29(1):1-6

区域地质调查（区调）是国家重要的基础性工作。近年来，随着我国经济、社会的快速发，调整区调工作布局，加快区调工作步伐已迫在眉睫。本从国民经济、社会发展的需求和国家“十五”计划的要求出发，分析了全国区调工作的现状和发展趋势，对依靠科技进步，调整区调部署、加快区调进度的紧迫性、可行性及目标任务进行了论述，指出了尽快将区调工作纳入全面服务社会的轨道、2005年优先安排并完成青藏高原空白区1；25万区调工作、2010年前全面完成全国中比例尺区调任务并出版中国第一套相关基础地质系列图件的基本思路。章特别指出，区调提速一定要确保野外填图的质量，工作部署一定要坚持实事求是的原则。要依靠计算机、遥感等高新技术实现区调提速，要在提速过程中实现区调工作主流程的信息化。  相似文献