TAKING INTO ACCOUNT THE EFFECT OF SECONDARY FLOWS IN DEPTH AVERAGED MORPHODYNAMIC SIMULATIONS     

Andreas MALCHEREK Research Engineer  Federal Waterways Engineering  Research Institute 《国际泥沙研究》2001,16(2)

1 INTRODUCTIONThe numerical simulation of morphological changes in rivers, estuaries and coastal areas is because ofits econondcal merit an outstanding scientific task. The comPlexity of the problem is connected with theheterogeneity of the sediment material, an adequate rePresentation of the involved hydrOdynndc stressesand the large comPutational effort fOr long term simulations.Although the aPpllcation of three dimensional models tO engineering problems is increasing and wellvalldate…  相似文献   

Quantification of salt weathering in porous stones using an experimental continuous partial immersion method   总被引：1，自引：0，他引：1  

D. Benavente  M. A. Garcí  a del Cura  A. Bernab  u  S. Ord    ez 《Engineering Geology》2001,59(3-4):313-325

In this study, an experimental salt weathering simulation and porous stone durability classification are proposed. There are many laboratory tests that quantify durability against salt crystallisation weathering action. These are usually based on the total immersion of samples into a saline solution, which is not representative of the salt weathering mechanism. An experimental test based on partial immersion is suggested. This is a comparable study of weight loss and degradation of visual appearance due to salt crystallisation using, on the one hand, a standard durability test (UNE), and, on the other, the proposed durability test. The weight loss and visual appearance in our test is comparable to the degradation of building stone. The differences between weight loss data in both tests depend on the petrophysical properties: porous media and degree of coherence.

From this testing, a new durability classification as a function of dry weight loss in the partial immersion test is proposed. Four divisions of different types of materials can be made in this classification, which quantifies salt weathering action mainly in environments and mild climatic conditions.  相似文献   

地震灾场的模拟与模拟控制问题研究（Ⅰ）地震灾场模拟   总被引：3，自引：0，他引：3  

李杰  宋建学 《地震工程与工程振动》1996,(2)

本文将离散事件系统仿真的方法引入到地震工程研究之中．在论述地震灾场模拟与离散事件系统仿真的共性与差异的基础上，以城市地震次生火灾的发生与扑救过程为背景，发展了场、时域复合仿真模型，提出了城市地震灾场的综合模拟算法．实例研究表明，本文建议的地震灾场模拟算法可以揭示复合型工程系统地震反应的一系列特征参数。  相似文献   

1：5万区域地质图编稿原图的制作     

王长才 《吉林地质》1993,12(1):77-79

目前,省内各地调单位在编制1∶5万区域地质图编稿原图时采用的方法、程序和依据的技术要求等方面尚不完全一致,直接且不同程度地影响了地质图件的质量。本文就上述问题,依据国家、部颁布的有关规程、规范及局的有关文件精神作了较全面系统的说明与论述,可望今后逐步走上统一标准。  相似文献   

Weathering of sulfidic shale and copper mine waste: secondary minerals and metal cycling in Great Smoky Mountains National Park,Tennessee, and North Carolina,USA   总被引：6，自引：0，他引：6  

Jane?M.?HammarstromEmail author  Robert?R.?SealII  Allen?L.?Meier  John?C.?Jackson 《Environmental Geology》2003,45(1):35-57

Metal cycling via physical and chemical weathering of discrete sources (copper mines) and regional (non-point) sources (sulfide-rich shale) is evaluated by examining the mineralogy and chemistry of weathering products in Great Smoky Mountains National Park, Tennessee, and North Carolina, USA. The elements in copper mine waste, secondary minerals, stream sediments, and waters that are most likely to have negative impacts on aquatic ecosystems are aluminum, copper, zinc, and arsenic because these elements locally exceed toxicity guidelines for surface waters or for stream sediments. Acid-mine drainage has not developed in streams draining inactive copper mines. Acid-rock drainage and chemical weathering processes that accompany debris flows or human disturbances of sulfidic rocks are comparable to processes that develop acid-mine drainage elsewhere. Despite the high rainfall in the mountain range, sheltered areas and intermittent dry spells provide local venues for development of secondary weathering products that can impact aquatic ecosystems.Electronic Supplementary Material  Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material.

Jane M. HammarstromEmail: Phone: +1-703-6486165Fax: +1-703-6486252

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人工多晶橄榄石样品孔隙压缩高温高压实验研究   总被引：1，自引：1，他引：0  

孙天泽 《地球物理学进展》2000,15(4):27-34

人工制备多晶橄榄石样品的高孔隙度是实验关注的问题之一。本文着重研究在给定温度条件下人工多晶橄榄石样品高温高压孔隙压缩问题。文中给出了含水的湿样品和干燥样品孔隙度与实验压力的关系曲线,并提出了衡量样品压实程度的压实系数Ｖｏ／Ｖ的概念。  相似文献   

Seismic diagnosis of railway substructures by using secondary acoustic emission     

Xiu Luo  Hiroshi Haya  Tomoaki Inaba  Tomoki Shiotani 《Soil Dynamics and Earthquake Engineering》2006,26(12):1101-1110

One difficult task for the seismic diagnosis of existing structures is how to nondestructively evaluate the damage degree of invisible substructures, such as embedded foundations. To diagnose substructures efficiently, a method for nondestructive inspection is developed by applying acoustic emission (AE) technique. As a newly proposed method, characteristics of secondary AE induced by train operations were investigated, and experiments using model piles and in-situ AE monitoring of in-service railway bridges conducted under railroad traffic, from which it was demonstrated that the proposed method is practicable enough to detect invisible defects in structures. A new index, known as RTRI (ratio of Repeated Train load at the onset of AE activity to Relative maximum load for Inspection period) is proposed for structural damage qualification based on the results of in-situ AE monitoring.  相似文献   

Determination of Porosity and Permeability out of Dispersion Analyses of Borehole Wall Displacements     

Michael Albrecht  Vladimir Mansurov 《Pure and Applied Geophysics》2006,163(10):2125-2140

Waves carried in the borehole can be measured by the use of controlled sources inside the borehole and receivers located in the same borehole as well. This article gives the theoretical background and develops a new method to determine rock-physical parameters out of such controlled measurements of waves carried inside the borehole. Theoretical dispersion curves of the group velocities are matched to dispersion analyses of registrations obtained in the borehole. This inversion process intends to determine the in situ porosity and permeability of the rock.  相似文献   

Characteristics of secondary circulations over an inhomogeneous surface simulated with large-eddy simulation     

Thara V. Prabha  Anandakumar Karipot  Michael W. Binford 《Boundary-Layer Meteorology》2007,123(2):239-261

Large-eddy simulation is used to study secondary circulations in the convective boundary layer modulated as a result of horizontally varying surface properties and surface heat fluxes over flat terrain. The presence of heat flux heterogeneity and its alignment with respect to geostrophic wind influences the formation, strength and orientation of organized thermals. Results show boundary-attached roll formation along heat flux maxima in the streamwise direction. The streamwise organization of the updrafts and downdrafts formed downwind of heterogeneities leads to counter-rotating secondary circulations in the crosswind plane. The distribution of resolved-scale pressure deviations shows large pressure gradients in the crosswind plane. Spanwise and vertical velocity variances and heat flux profiles depict considerable spatial variability compared to a homogeneous forest simulation. Secondary circulations are observed for various ambient wind scenarios parallel and perpendicular to heterogeneities. In the presence of increased wind speed, thermals emerging from the heat flux heterogeneity are elongated, and organize along and downwind of large-scale heterogeneity in the streamwise direction. Simulation with a reduced heat flux shows a shallower circulation with a lower aspect ratio. Point measurements of heat flux inside the roll circulation could be overestimated by up to 15–25% compared to a homogeneous case.  相似文献   

山西晋城矿区成庄井田3号煤储层的物性研究     

王占磊  曾勇  吴财芳 《江苏地质》2007,31(1):30-33

对研究区内3号煤储层的几何形态、割理和孔隙系统进行了研究,并引入了储层结构综合指数(SI)来评价研究区内煤层透气性特征和甲烷运移能力,并得出了如下结论:①全区煤层厚度稳定,是煤层甲烷的良好储集层;②根据全区割理发育程度推测出,构造主应力来自NE-SW方向;③通过孔隙系统研究,3号煤层基本上属于非渗透性储层;④成庄井田3号煤层结构综合指数(SI)等值线平面图,显示了煤层透气性由东北向西南呈逐渐变差的趋势。  相似文献