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91.
92.
红层软岩边坡生态防护技术探讨 总被引:1,自引:0,他引:1
红层软岩边坡,土质贫瘠,浅层稳定性差,生态防护失效的现象比较突出。为提高西部红层软岩边坡生态防护的可靠性,在对西部红层软岩地区铁路、公路边坡生态防护状况进行调研和分析的基础上,总结红层软岩边坡生态防护失败的原因,吸取经验教训,提出适于红层软岩边坡的生态防护方法和适合该区栽植的草木品种及配置方法。 相似文献
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94.
本文对西安国贸大厦沉降监测技术方案进行了讨论,着重结合有关工程地质资料对沉降进行了几何分析和物理分析,探讨了沉降引发的原因及建筑物变形规律 相似文献
95.
关于虚拟地理环境研究的几点思考 总被引:10,自引:0,他引:10
该文主要回答了目前被频繁问及的有关虚拟地理环境的几个问题。重点阐述了虚拟地理环境的概念、发展现状及其基本理论、方法、关键技术与应用,以及与传统地理信息系统的区别。指出虚拟地理环境是在空间数据库和地理模型管理基础上构建的、同时表达地理静态和模拟动态现象的、面向多用户的分布式协同虚拟环境。因此,虚拟地理环境突破地理信息系统以数据共享为核心的框架,走向以数据库和模型库为双核心的知识共享平台,进而形成一个新知识的生成环境。 相似文献
96.
古尔班通古特沙漠是中国第二大沙漠,也是中国固定和半固定沙丘主要分布区,固沙灌木种较多。冠幅不仅是反映固沙灌木可视化的重要参数,也是反映沙漠植被生长情况的重要变量。以3种沙丘(固定沙丘、半固定沙丘和流动沙丘)上主要固沙灌木为研究对象,利用12种基础模型、BP(Backpropagation Neural Network)神经网络和支持向量机(Support Vector Machine,SVM)机器学习算法建立了基于固沙灌木株高和冠长率的冠幅预测模型,同时将两种机器学习算法拟合结果与基础模型进行比较,最终选出了适合研究区的冠幅预测模型。结果表明:(1)不同沙丘类型和不同灌木种类的最优冠幅预测模型不同,且固定沙丘和半固定沙丘模型优于流动沙丘。3种沙丘类型最优拟合为M2(Quadratic Model)模型;(2)白梭梭(Haloxylon persicum)在半固定沙丘和流动沙丘上拟合的最优模型分别为M2、M7(Gompertz),沙拐枣(Calligonum mongolicum)最优模型为M2,蛇麻黄(Ephedra distachya)和油蒿(Artemisia ordosica)在... 相似文献
97.
G. H. McNally 《Australian Journal of Earth Sciences》2013,60(6):535-547
The uses and shortcomings of duricrusts (ferricrete, calcrete and silcrete) in engineering construction (as used for road‐base, aggregate, foundation materials and aquifers) are reviewed. Australian production of these materials represents about one‐third of all unprocessed road‐base and they are especially important as pavement courses for lightly trafficked, low‐cost rural and outback roads. However, duricrusts are regarded as marginal materials at best because of their typically poor grading, particle unsoundness, high fines plasticity, and absorption of water and bitumen. These materials are used because they are available locally in areas that are otherwise lacking in hard rock materials, such as deeply weathered and sedimentary rock terrains. The weathering profiles of which they form part are characterized by high permeability (despite being clay‐rich), variable cementation, low compressibility and a tendency to become weaker with depth. Although the more indurated layers are unrippable, they are also difficult to blast. Pedogenic (nodular) duricrusts were formerly sought for natural road‐base, because they occur widely and require only rudimentary processing. However, well‐cemented groundwater (vadose) duricrusts are now the preferred deposits, even though they require crushing and screening. Ferricrete is the most widely exploited of the duricrusts for engineering purposes, especially in northern and southwestern Australia, although calcrete is important in South Australia and in the Murray Basin. Silcrete is only a minor source of aggregate and road‐base, mainly in western Queensland. 相似文献
98.
This article presents a method for the nonlinear analysis of laterally loaded rigid piles in cohesive soil. The method considers the force and the moment equilibrium to derive the system equations for a rigid pile under a lateral eccentric load. The system equations are then solved using an iteration scheme to obtain the response of the pile. The method considers the nonlinear variation of the ultimate lateral soil resistance with depth and uses a new closed‐form expression proposed in this article to determine the lateral bearing factor. The method also considers the horizontal shear resistance at the pile base, and a bilinear relationship between the shear resistance and the displacement is used. For simplicity, the modulus of horizontal subgrade reaction is assumed to be constant with depth, which is applicable to piles in overconsolidated clay. The nonlinearity of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The validity of the developed method is demonstrated by comparing its results with those of 3D finite element analysis. The applications of the developed method to analyze five field test piles also show good agreement between the predictions and the experimental results. The developed method offers an alternative approach for simple and effective analysis of laterally loaded rigid piles in cohesive soil. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
99.
《水文科学杂志》2013,58(4)
Abstract The management of water excesses and deficits is a major task in semiarid Mediterranean regions, where the variability of rainfall inputs is high at different time and space scales. Thus intense hydrometeorological events, which generate both potential resource and hazards, are of major interest. A simple method is proposed, with the example of the Skhira basin (192 km2) in central Tunisia, to account for the event space–time variability of rainfall in a rainfall–runoff model, in order to check its influence on the shape, magnitude and timing of resulting hydrographs. The transfer function used is a geomorphology-based unit hydrograph with an explicit territorial significance. Simulations made for highly variable events show the relevance of this method, seen as the first step of a downward approach, and its robustness with respect to the quality and the density of rainfall data. 相似文献
100.
《水文科学杂志》2013,58(5)
Abstract A revised approach to the calculation of baseflow using the method originally proposed by the United Kingdom Institute of Hydrology is presented. The revisions resolve two aspects of the method that lead to less than optimal results; that is, the calculation of values of baseflow that exceed the corresponding values of streamflow and the dependence of the calculated values on the origin of the five-day segmentation of the input streamflow data. The approach is illustrated using streamflow monitoring information that is typical for areas of southern Ontario, Canada, where baseflow is primarily the result of groundwater discharge. 相似文献