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41.
A Procedure for Determining the Reaction Curve of Shotcrete Lining Considering Transient Conditions 总被引:6,自引:0,他引:6
P. P. Oreste 《Rock Mechanics and Rock Engineering》2003,36(3):209-236
Summary
The mechanical behaviour of a shotcrete lining is analysed in this paper using the convergence-confinement approach. A calculation
procedure is presented which is able to provide the reaction curve of a lining with increasing stiffness, by taking into account
the variability due to time of the shotcrete stiffness and strength, as well as the face advancement rate. The proposed procedure
is also able to provide the change of the safety factor of the lining in time. This results to be a very useful tool for understanding
the behaviour of this widely used support and for assigning its thickness to guarantee stability (also in transient conditions),
with a known safety factor, during tunnel excavation.
Received May 25, 2001; accepted July 18, 2002; Published online January 21, 2003
Acknowledgements The author would like to thank Prof. S. Pelizza and Dr. S. Xu for the help given during the preparation of this paper. The
help of the Editor G. Barla is also acknowledged.
Authors' address: Dr. P. P. Oreste, Department of Earth Resources and Land, Politecnics di Torino, corso Duca degli Abruzzi 24, 1-10129 Torino,
Italy; e-mail: oreste@polito.it 相似文献
42.
A comparison of three image-object methods for the multiscale analysis of landscape structure 总被引:4,自引:0,他引:4
Geoffrey J. Hay Thomas Blaschke Danielle J. Marceau Andr Bouchard 《ISPRS Journal of Photogrammetry and Remote Sensing》2003,57(5-6):327
Within the conceptual framework of Complex Systems, we discuss the importance and challenges in extracting and linking multiscale objects from high-resolution remote sensing imagery to improve the monitoring, modeling and management of complex landscapes. In particular, we emphasize that remote sensing data are a particular case of the modifiable areal unit problem (MAUP) and describe how image-objects provide a way to reduce this problem. We then hypothesize that multiscale analysis should be guided by the intrinsic scale of the dominant landscape objects composing a scene and describe three different multiscale image-processing techniques with the potential to achieve this. Each of these techniques, i.e., Fractal Net Evolution Approach (FNEA), Linear Scale-Space and Blob-Feature Detection (SS), and Multiscale Object-Specific Analysis (MOSA), facilitates the multiscale pattern analysis, exploration and hierarchical linking of image-objects based on methods that derive spatially explicit multiscale contextual information from a single resolution of remote sensing imagery. We then outline the weaknesses and strengths of each technique and provide strategies for their improvement. 相似文献
43.
高耸塔架结构节点损伤基于神经网络的两步诊断法 总被引:15,自引:1,他引:15
本文针对高耸钢塔架结构的损伤特点,建立了具有节点损伤的有限元模型,提出了一种分层神经网络两步诊断法:第一步,由基于区域残余力理论的第一层神经网络进行结构损伤区域的初诊;第二步,由基于应变模态理论的第二层神经网络进行损伤区域内的具体损伤节点位置和程度的诊断。对一平面塔架结构的数值仿真分析表明:本文提出的损伤诊断方法的结果是令人满意的。 相似文献
44.
隧道GPS网对横向贯通误差的影响 总被引:4,自引:0,他引:4
本文在阐述隧道工程独立坐标系和隧道GPS网数据处理方法的基础上推导出GPS网对横向贯通误差影响的通用计算公式,分析了隧道GPS网基准数据位置对横向贯通误差的影响。 相似文献
45.
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47.
Peter M. Atkinson 《International Journal of Applied Earth Observation and Geoinformation》2004,5(4):277-291
A simple approach for incorporating a spatial weighting into a supervised classifier for remote sensing applications is presented. The classifier modifies the feature-space distance-based metric with a spatial weighting. This is facilitated by the use of a non-parametric (k-nearest neighbour, k-NN) classifier in which the spatial location of each pixel in the training data set is known and available for analysis. A remotely sensed image was simulated using a combined Boolean and geostatistical unconditional simulation approach. This simulated image comprised four wavebands and represented three classes: Managed Grassland, Woodland and Rough Grassland. This image was then used to evaluate the spatially weighted classifier. The latter resulted in modest increase in the accuracy of classification over the original k-NN approach. Two spatial distance metrics were evaluated: the non-centred covariance and a simple inverse distance weighting. The inverse distance weighting resulted in the greatest increase in accuracy in this case. 相似文献
48.
49.
The neoliberalization of ecosystem services: wetland mitigation banking and problems in environmental governance 总被引:1,自引:0,他引:1
Morgan M. Robertson 《Geoforum》2004,35(3):361-373
Wetland mitigation banking is an American neoliberal environmental policy that has created a functioning market in `ecosystem services', commodities defined using the holistic measures of ecological science. The development of this market is discussed as a project of environmental governance, defined as the nation-state's regulation of ecological relations within its territory towards stabilizing capitalist relations of power and accumulation. I argue that the wetland banking industry serves as a bellwether that presages problems that other strategies of neoliberal environmental governance will experience. Ethnographic, economic and ecological data from the Chicago-area wetland banking industry inform a discussion of two major obstacles to neoliberal strategy: the problem of relying on ecological science to define the unit of trade, and the problem of aligning the somewhat independent relations of law, politics, markets and ecosystems across an array of spatial scales. Theoretical guidance is sought from recent work on `social natures' and from the Regulationist approach to institutional political economics. 相似文献
50.
Mohammad M. Sohrabi Rohan Benjankar Daniele Tonina Seth J. Wenger Daniel J. Isaak 《水文研究》2017,31(9):1719-1733
Stream water temperature plays a significant role in aquatic ecosystems where it controls many important biological and physical processes. Reliable estimates of water temperature at the daily time step are critical in managing water resources. We developed a parsimonious piecewise Bayesian model for estimating daily stream water temperatures that account for temporal autocorrelation and both linear and nonlinear relationships with air temperature and discharge. The model was tested at 8 climatically different basins of the USA and at 34 sites within the mountainous Boise River Basin (Idaho, USA). The results show that the proposed model is robust with an average root mean square error of 1.25 °C and Nash–Sutcliffe coefficient of 0.92 over a 2‐year period. Our approach can be used to predict historic daily stream water temperatures in any location using observed daily stream temperature and regional air temperature data. 相似文献