全球地质学复兴：我们正进入“人类幻”——第32届国际地质大会环境地质述评   总被引：4，自引：2，他引：4  

殷跃平 《地质通报》2005,24(2):99-103

概要介绍了第32届国际地质大会的议题概况。7个大会报告中与环境地质问题相关的竟有6个，反映以人类与地球相互作用为中心的研究已成为地质学家们不得不关注的主题。重点介绍了环境地质方面的几个重要议题：气候与地质环境、地质灾害风险评估、城市化与城市地质、地下水资源与环境、地质环境标识。阐明了关于全球地质学复兴的几点思考：人类活动已成为一种地质营力、地质工作者应成为管理地球的主力军、重在预测人类的未来、地质环境与地球环境、地球系统与地球问题。  相似文献   

A double structure generalized plasticity model for expansive materials   总被引：1，自引：0，他引：1  

Marcelo Snchez  Antonio Gens  Leonardo do Nascimento Guimares  Sebastin Olivella 《国际地质力学数值与分析法杂志》2005,29(8):751-787

The constitutive model presented in this work is built on a conceptual approach for unsaturated expansive soils in which the fundamental characteristic is the explicit consideration of two pore levels. The distinction between the macro‐ and microstructure provides the opportunity to take into account the dominant phenomena that affect the behaviour of each structural level and the main interactions between them. The microstructure is associated with the active clay minerals, while the macrostructure accounts for the larger‐scale structure of the material. The model has been formulated considering concepts of classical and generalized plasticity theories. The generalized stress–strain rate equations are derived within a framework of multidissipative materials, which provides a consistent and formal approach when there are several sources of energy dissipation. The model is formulated in the space of stresses, suction and temperature; and has been implemented in a finite element code. The approach has been applied to explaining and reproducing the behaviour of expansive soils in a variety of problems for which experimental data are available. Three application cases are presented in this paper. Of particular interest is the modelling of an accidental overheating, that took place in a large‐scale heating test. This test allows the capabilities of the model to be checked when a complex thermo‐hydro‐mechanical (THM) path is followed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

区域可持续发展中的环境伦理问题   总被引：9，自引：3，他引：9  

郑度 《地理研究》2005,24(2):161-168

全世界面临着人口、资源、环境和发展等一系列问题和严重挑战。当前要实施全面、协调、可持续的科学发展观,贯穿其中的主线是树立正确的环境伦理意识,协调处理好人与自然的关系,促进区域可持续发展。人类是地球自然界的一部分,只有以全球整体利益为出发点处理环境与发展问题,才有较大的安全性和包容性。应当以尊重自然及其内在价值为基础来规范人类的实践活动,构建新时代的文明发展模式。环境伦理与可持续发展观在形成和社会功能上有密切的联系。要实施可持续发展战略,必须十分重视环境伦理的研究、教育和实践。实现人与自然和谐的可持续发展是政府和社会公众的共同责任。环境伦理在区域可持续发展中涉及的应用领域很广,要重视地球系统科学知识的宣传普及,提高公民和决策者的环境意识与可持续发展的伦理观念。  相似文献   

Agribusiness and farmers in Mexico: the importance of contractual relations   总被引：1，自引：0，他引：1  

FLAVIA ECHÁNOVE  CRISTINA STEFFEN† 《The Geographical journal》2005,171(2):166-176

In recent decades contract farming as a mechanism that integrates and subordinates agricultural production to export oriented agribusiness has expanded in Third World countries. In Mexico contract farming dominates the production of horticultural crops for processing and export. It is also used for barley and to grow some varieties of wheat for Cargill . The contract farming labour agreement represents an institution that links local and global processes where agribusiness is the key actor that integrates local farmers to national and world markets. The purpose of this paper is to analyse the implications of contract farming for productive relations by examining its impact upon farmers and firms. The study found that despite the disadvantages of contract farming for growers, and the disproportional risks born by producers, they enter into contract farming labour agreements because they lack alternatives for financing, technical assistance and access to markets. The experience of contract farming in Mexico and several Third World countries shows that its growth is related to the implementation of neo-liberal policies that are accompanied by the withdrawal of state support and regulation of agricultural production. In this context, contract farming represents a livelihood strategy for many Mexican growers.  相似文献   

干旱区人水和谐治水思想的探讨   总被引：2，自引：3，他引：2  

邓铭江 《干旱区地理》2007,30(2):163-169

在温故古人治水思想的基础上,认真总结和深刻领悟现代治水新思路,并针对干旱区内陆河流域径流形成、利用、转化、耗散等水循环特征和经济社会发展与生态环境保护在用水方面的突出矛盾,反思水资源在开发、利用、治理、配置、节约和保护等水事活动中存在的诸多问题,提出了“治河之术,治水之学,治域之理,人水和谐之道”的治水思想。这是实施资源水利战略,实现水资源可持续利用目标的重要思想理论基础,对于其它流域或区域治水方略的确立也具有广泛的借鉴意义。  相似文献   

蒸发蒸腾作用下非饱和土的吸力和变形影响因素分析   总被引：3，自引：0，他引：3  

陈建斌  孔令伟  赵艳林  吕海波 《岩土力学》2007,28(9):1767-1772

采用热湿耦合非等温流方程,结合实际蒸发和植物蒸腾的边界条件,考虑了水分迁移所引发的非饱和土应力变形行为,从而建立了大气-非饱和土相互作用模型。采用该模型对控制非饱和土吸力和变形的大气蒸发和植物蒸腾等多参数进行了影响程度分析。结果表明,控制地面吸力和变形的主导因素是外部气象条件,尤其太阳净辐射量和风速,土体水力和热力特性参数影响程度有限;在植被覆盖条件下,吸力变化主要取决于植物叶面积指数LAI,而总腾发量的大小决定了地表变形量。  相似文献   

我国城市化发展的新特点及其区域空间建设策略   总被引：11，自引：0，他引：11  

姚士谋  管驰明  王书国  陈爽 《地球科学进展》2007,22(3):271-280

经济全球化成为21世纪最具有广泛影响的事件，将促进全球城市化的高速发展。我国正处在城市化高度发展时期，城市化出现“集群式”发展、城乡二元结构扩大、“驱赶型城镇化”和城市化的区域空间差异性等新特点、新问题。我国快速城市化过程中出现的新矛盾、水土资源流失与大量占用，对沿海地区一些城市的区域环境产生了很多负面影响，诸如酸雨、城市污染、汽车烟雾和交通阻塞等。面对全球城市化的巨大影响与冲击，从区域空间角度出发，提出必须在科学发展观和构建和谐社会的指导下，使我国城市化走向健康之路，实施区域空间建设新策略，注重大城市群区内的保护与建设，因地制宜、合理利用、适度发展、构建区域性的生态安全格局，促进我国信息化的区域合作。  相似文献   

On the linear relation between m_b and M_s for discrimination between explosions and earthquakes     

All A. Nowroozi 《Geophysical Journal International》1986,86(2):687-699

Summary. The statistical capability of the m _b: M _s discriminant for the discrimination of earthquake and explosion populations is examined by application of discriminant functions to a group of 83 explosions and 72 earthquakes in Eurasia. Equations are derived for the probability that an event is an earthquake or an explosion. The positive sign of DIS in the decision index equation, DIS _i = 34.3383 – 11.9569 mb _t + 7.1161 M _si , indicates that the event i is an earthquake. Its negative sign indicates that event i is an explosion. The probability of correct classification for an event, P _i , is related to its DIS _i value, by P _i = [1-exp (DIS _i )]⁻¹, where a large, positive DIS indicates a high probability that an event is an earthquake and a large, negative DIS indicates a high probability that an event is an explosion. The discrimination line M _s = 1.680 m _b– 4.825, or m _b= 0.595 M _s+ 2.872 very successfully separates the explosion population from the earthquake population. The points on this line have an equal chance of being an earthquake or an explosion; moreover, for any event, the distance parallel to the M _s-axis from the point representing that event in the m _b: M _s plane to this line is a measure of the probability for the correct classification of that event.  相似文献   

承压水井水位固体潮扩散方程的解和含水层参数的求定     

骆鸣津  杨毅  李安印  顾梦林 《大地测量与地球动力学》1994,(4)

本文在求解承压水井水位固体潮的扩散方程时增加了井孔压力的边界条件，使扩散方程更符合实际情况，从而得到在理论上更为完善的起潮力位与水位固体潮之间的关系式。文中讨论了气压作用于承压含水层的水力扩散方程和气压对水位固体潮的影响，导出了相位滞后与含水层参数的解析式，为求解含水层参数建立了基础。根据水位固体潮观测资料和气压观测资料，在给定地球模型的勒夫数的情况下，全面地解决了求定观测井含水层参数的方法，并给出了一个实际算例。  相似文献   

Shear strength characteristics of sand-mixed with granular rubber   总被引：1，自引：0，他引：1  

Mahmoud Ghazavi 《Geotechnical and Geological Engineering》2004,22(3):401-416

Waste materials such as waste tires, rubbers, and plastic materials are normally produced in every society, entering the environment and causing serious problems. These problems may be somehow reduced by finding applications for them in engineering, for example, as lightweight materials for backfill in geotechnical projects. To this aim, this paper demonstrates how shear strength characteristics of sand mixed with various percentages of waste garden hose grains are altered. A relatively, uniform sand has been mixed with waste hose grains in loose and slightly compacted states. Waste hose grains were prepared with special popular machinery in a local area. Various sand-rubber mixtures having 0%, 10%, 15%, 20%, 50%, 70%, and 100% waste hose particles by weight were chosen. The rubber grains were distributed in the sand such that uniform mixtures are obtained. In order to compare the shear strength of different sand-rubber samples, two compaction states were considered. The results show that the influencing parameters on shear strength characteristics of sand-rubber mixtures are normal stress, mixture unit weight, and rubber content. With the selected waste hose particles, compaction states, and rubber contents, the initial friction angle φ₁ does not change significantly. However, an apparent cohesion appears in the mixtures. From environmental point of view and due to lightweight material for the sand-waste hose particles, it may be useful to use such materials in corresponding geotechnical projects. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献