乌鲁木齐市近断层场地的有限元动力反应分析     

刘云华  柔洁  张晓帆 《内陆地震》2007,21(1):44-49

根据活断层性质、倾角及上覆层厚度等因素,按照一定的比例关系,利用有限元软件建立了8个活断层场地模型,并以地震动作为输入,对这些模型进行了地震分析计算。最后对结果进行了综合对比分析,讨论了断层倾角、上覆层厚度等因素与断层破裂带之间的关系,力图从城市规划与建设的角度,对建筑物与活动断裂之间的安全距离做一探讨。  相似文献   

Freezing rain events: a major weather hazard in the conterminous US   总被引：3，自引：0，他引：3  

Tamara G. Houston  Stanley A. Changnon 《Natural Hazards》2007,40(2):485-494

Freezing rain (FZRA) is well documented as a major weather hazard, producing damage to structures, the environment, and humans, and delaying various operations such as transportation. Assessing the risk of freezing rain events requires information for various areas of the nation about the frequency, duration, and intensity of these events along with the associated weather conditions that affect the damage caused by freezing rain. This includes temperatures (dry and wet bulb), the amount of precipitation, and winds during freezing rain. The purpose of this work was to develop a national and regional climatology of freezing rain events in the US for the period of 1928–2001 to addresses these conditions.  相似文献   

青藏块体东北缘地壳运动与孕震特征   总被引：6，自引：2，他引：4  

张晓亮  江在森  王双绪  张希  陈兵  崔笃信 《大地测量与地球动力学》2004,24(4):76-81

为了探索昆仑山口西Ms8．1大震后青藏块体东北缘中强地震相对活跃的原因，利用近几年来的GPS观测资料，用有限元方法研究了该区的水平运动变形与孕震特征，结合其它成果分析得到：1)昆仑大震对青藏块体东北缘的运动变形产生相当影响，对其西部的影响亦很大；2)差异运动强烈区域发生中强地震的危险性较高，压性区可能是应变能积累的反映，而张性区的出现及规模可能是大震发生紧迫性及震级大小的反映；3)研究区的西部地区近年来一直是应变能积累较快的地区，从区域变形特征与强震的对应关系看，近一两年发生中强地震的危险性仍然很大。  相似文献   

地下水流的有限分析数值解     

王文科  李俊亭 《地球科学与环境学报》1993,(Z2)

本文介绍了一种求解地下水流问题的有限分析法,该方法将解析解结合到数值方法中,从而提高了计算精度,改善了稳定性。算例表明,在网格尺寸相同的情况下,有限分析解比有限差分解高一个数量级,与解析解吻合很好。  相似文献   

Characteristics of Thermal and Geopotential Height Differences Between Continent and Ocean and Its Role in the Strength of the Asian Summer Monsoon     

Andrea Silverman SUN Jilin 《中国海洋大学学报(英文版)》2005,4(4):366-376

The interdecadal factors affecting the summer monsoon winds over Somalia and the South China Sea were studied. Global geopotential heights and wind velocity fields of the 850-hPa and 200-hPa pressure levels, as well as sea surface temperature anomaly data and correlation coefficients were analyzed. The monsoons over Somalia and the South China Sea were found to be two different monsoon systems, operating on different mechanisms and being affected by different ocean-atmosphere interactions. The intensity of the Asian subtropical summer monsoon is influenced by the intensity of the summer monsoon over Somalia in the month of June and by the intensity of the summer monsoon over the South China Sea in the months of June and July. The summer monsoon wind strength over Somalia is affected by regional factors, such as the heating of the Tibetan plateau, and by global mechanisms, such as the subtropical heat exchange with Antarctica. The summer monsoon over the South China Sea is affected by different ocean-atmosphere interactions. The Somalia and subtropical summer monsoons have wind blowing down the pressure gradient from area over ocean to that over land, like typical summer monsoons. The South China Sea summer monsoon has winds that blow down the pressure gradient from area over land to that over ocean. The South China Sea summer monsoon is affected by the Kuroshio Current off the east coast of Japan.  相似文献   

豫西地区土地分异规律及合理利用研究   总被引：3，自引：0，他引：3  

周国强  张青 《地域研究与开发》2004,23(4):126-128

文章论述了土地是地球表面各自然要素相互作用的历史产物，是一种复杂的带有人类活动烙印的自然综合体。由于组成土地的各种自然要素的综合特征以及受人类活动的影响程度互有差异，所以，形成了一系列互不相同，各具特色的土地。文章分析了豫西地区各类土地的自然特征，从而能因地制宜地发展各项生产，提高土地的生产潜力，更加合理地利用和保护土地资源。  相似文献   

Women and the access to knowledge and new technologies: The case of Pisa     

Gisella Cortesi  Michela Lazzeroni 《GeoJournal》2004,60(3):229-237

Emphasis has been given to a number of aspects which characterise technological development in today's economic systems and which have an impact on the working environment and on gender differences. Technological change is leading to a strong divide between knowledge “producers” and “users”. The possibility of access to one or both knowledge systems indicates the extent of women's participation in the economic and spatial transformations brought about by the new technologies. This research aims to analyse the development of new technologies and the presence of the female workforce in the field of new knowledge generation, and also to verify gender-related conditions in learning and using new technologies. In particular, an analysis has been carried out of the empirical case study of Pisa, a point of reference for comparisons with other Italian and European cases. The research focuses on: the examination of women's capabilities in the field of new technologies through the analysis of University training courses; the analysis of women's presence and status among the university staff, especially in science and technology; a detailed survey of female employment in innovative sectors. The results of the research emphasise the gender perspectives of inclusion — as regards the application of technologies — and exclusion — as regards the generation of knowledge — of women in or from new technologies. At the same time, the research stresses the growth of women's roles in this sector during recent years and, by reconstructing life histories, underlines the conditions and difficulties that have been met by women entering these new types of employment. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Numerical simulation of geotechnical problems based on a multi-phase finite element approach     

G. Oettl  R.F. Stark  G. Hofstetter 《Computers and Geotechnics》2004,31(8):643-664

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Pore pressure tension cut off in two-phase finite element analyses     

Annamaria Cividini  Giancarlo Gioda 《Computers and Geotechnics》2004,31(8):613-624

In the coupled finite element analysis of the two-phase, saturated soils the pore pressure could decrease below the atmospheric pressure in particular when the plastic dilation of the skeleton is accounted for. The consequent reduction of the bulk modulus of the liquid phase is here modelled in a simplified manner through a tension cut off on the pore pressure. Two alternative approaches are outlined in the framework of the finite element method. The first one introduces a unilateral constraint on the nodal pore pressures and involves manipulations on matrices of the assembled mesh, whilst the second approach requires calculations solely at the element level. The effects of the pore pressure tension cut off are illustrated through some undrained test examples in elastic–plastic regime.  相似文献   

Three-dimensional analysis of embankments on soft soils incorporating vertical drains by finite element method   总被引：4，自引：0，他引：4  

Jos Leito Borges 《Computers and Geotechnics》2004,31(8):665-676

Three-dimensional behaviour of an embankment on soft soils incorporating vertical drains is analysed by a numerical model based on the finite element method. The model, which incorporates the Biot’s consolidation theory (coupled formulation of the flow and equilibrium equations) and constitutive relations simulated by the p–q–θ critical state model, is applied on both the embankment with vertical drains (three-dimensional analysis) and the same problem but without vertical drains (two-dimensional analysis). Special emphasis is given to the analysis, during and after the construction period, of the excess pore pressures, settlements, horizontal displacements and stress levels.  相似文献