CATASTROPHIC ECO-ENVIRONMENTAL CHANGE IN THE SONGNEN PLAIN, NORTHEASTERN CHINA SINCE 1900S   总被引：1，自引：1，他引：0  

WANGHai-xia WANZhong-juan YUShao-peng LUOXin-zheng SUNGuang-you 《中国地理科学(英文版)》2004,14(2):179-185

Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thorn Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.  相似文献   

柴达木盆地东北缘古元古代变质镁铁—超镁铁质岩的地质特征及成因探讨     

王毅志  梁超云 《青海国土经略》2001,(Z1)

1:5万区域地质调查工作中,在柴达木陆块北缘首次发现古元古代变质镁铁—超镁铁质岩,获得成岩年龄为1952±15Ma,其岩石化学、地球化学特征反映出岩浆来源于亏损地幔,反映出该地区克拉通在古元古代(19亿年)发生了一次强烈的裂解(洋)事件,对于研究柴达木盆地北缘元古代结晶基底地质构造演化及进一步探讨柴达木盆地的起源及构造演化过程提供了重要地质线索。  相似文献   

定水头注水引起的含水层水平运动和应变   总被引：2，自引：2，他引：0  

王庆良  冉兴龙 《大地测量与地球动力学》2001,21(4):26-32

基于含水层固体颗粒与孔隙水不可压缩的假设 ,本文导出了单井注水情况下泰斯承压含水层水平运动速度与水头之间的基本关系式。然后利用注水井壁处的应力、应变边界条件 ,进一步导出了单井定水头注水引起的泰斯承压含水层水平运动速度、位移和应变解析表达式。该水平位移与应变由两部分组成 :一部分为由注水压力本身引起的经典弹性力学解项 ,它仅随半径而变化 ,与注水时间无关 ;另一部分为由地下水头变化引起的水动力学位移和应变解项。其中 ,含水层水动力学水平位移随时间加长呈指数增长特征 ,水动力学径向应变则表现为近井处拉张、远井处挤压的分区特征 ,且近井拉张区随时间加长逐渐向外扩展。单井注水含水层水动力学水平位移、应变解的导出 ,完善和发展了单孔内压经典弹性平面力学问题解  相似文献   

Vertical stress distribution due to an arbitrarily shaped foundation using triangulation and an analytical expression for a triangular loaded region     

V. Murti  Y. C. Wang 《国际地质力学数值与分析法杂志》1991,15(1):51-60

Using the basic Boussinesq's equation, the expression for the vertical stress distribution (σ_z) underneath any point on the ground surface due to a general triangular loaded region in a preferred orientation with a linearly varied loading has been successfully derived. When the triangle is not in a preferred orientation, a simple axis transformation is required and the expression will be equally applicable. Based on this expression, σ_z due to an arbitrarily shaped loaded foundation can simply be determined by first triangulating the loaded area and summing up the contributions from each generated triangular region. The procedures for triangulating and calculating the stress distribution can be simply automated through computer programs.  相似文献   

THE CHARACTERISTIC OF MARINE ENVIRONMENT IN LINGDINGYANG ESTUARY     

CHEN Bing-lu  ZHANG Yun-ni  CHEN Xin-geng  WANG Zhi-gang  YANG Guang-xing 《中国地理科学(英文版)》2001,11(2):155-162

1 HYDROLOGIC FEATURES Lingdingyang Estuary, located at the middle south of Guangdong Province, is a bell-shaped estuary with a north-south direction. Its area is about 2100km2. The north of Qi′ao Island and Inner-Lingding Island, and the south of Humen are grouped as Neilingdingyang Estuary, having an area of 1041km2. Affected by topography, runoff and tide, its dynamic condition is very complicated. Different water areas have different hydrologic features. The topography under …  相似文献   

A Simulating Experiment in the Process of Soil Erosion on Bare Land in Mt. Tanakami     

ZHAO Wei  HU Ke  Wang Xikui  Akitsu Kimoto  Takahisa MIZUYAMA 《世界地质(英文版)》2001,4(2)

In order to understand the process of surface erosion and acquire basic data of conditions on hillslope without vege tation, a sprinkling experiment is conducted on a bare slope in Mt. Tanakami in the central part of Japan. Based on the mea surements of runoff, mean soil erosion depth, and sediment yield, etc. , the results suggest the following characteristics in the process of surface erosion in the experimental area. (1) The occurrence of sediment discharge is interrupted; (2) Surface runoff is a saturated overland flow; (3) The mean soil erosion depth is thick compared with other areas in Mt. Tanakami;(4) Sediment discharge process is detachment- limited.  相似文献   

图形软件在编辑出版专题地图中的应用研究     

王大新 《地球信息科学学报》2001,3(2):25-28

计算机制图(CAC)和电子出版系统的普及和推广,从根本上改变了传统的地图生产工艺。本文结合制图实践,讨论了应用Coreldraw图形软件编辑出版专题地图的适应性、系统条件和工艺流程,并总结了一些制图经验和应该注意的若干问题。  相似文献   

Elastic solutions for stresses in a transversely isotropic half‐space subjected to three‐dimensional buried parabolic rectangular loads     

Cheng‐Der Wang  Jyh‐Jong Liao 《国际地质力学数值与分析法杂志》2002,26(14):1449-1476

In many areas of engineering practice, applied loads are not uniformly distributed but often concentrated towards the centre of a foundation. Thus, loads are more realistically depicted as distributed as linearly varying or as parabola of revolution. Solutions for stresses in a transversely isotropic half‐space caused by concave and convex parabolic loads that act on a rectangle have not been derived. This work proposes analytical solutions for stresses in a transversely isotropic half‐space, induced by three‐dimensional, buried, linearly varying/uniform/parabolic rectangular loads. Load types include an upwardly and a downwardly linearly varying load, a uniform load, a concave and a convex parabolic load, all distributed over a rectangular area. These solutions are obtained by integrating the point load solutions in a Cartesian co‐ordinate system for a transversely isotropic half‐space. The buried depth, the dimensions of the loaded area, the type and degree of material anisotropy and the loading type for transversely isotropic half‐spaces influence the proposed solutions. An illustrative example is presented to elucidate the effect of the dimensions of the loaded area, the type and degree of rock anisotropy, and the type of loading on the vertical stress in the isotropic/transversely isotropic rocks subjected to a linearly varying/uniform/parabolic rectangular load. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Paleoproterozoic Extensional Structure and Its Controlling on Mineralization in the East of Liaoning Province     

Yang Zhongzhu  Chen Shuliang  Li Xiandong  Wang Zhongjiang  Qu Hongxiang  Gang Jiang 《东北亚地学研究》2001,(1)

IntroductionThe area of eastern Liaoning is an importantmetal and nonmetal metallogenetic district in China,and the Liaohe group is one of the most importantstrata that hosts Pb, Zn, Au, B and Mg etcstratabound deposits. Up to now many geo1ogistssuch as Z…  相似文献   

The influence of a non‐associated flow rule on the calculation of the factor of safety of soil slopes     

Yu‐Jie Wang  Jian‐Hua Yin  C. F. Lee 《国际地质力学数值与分析法杂志》2001,25(13):1351-1359

This paper presents a method that incorporates a non‐associated flow rule into the limit analysis to investigate the influence of the dilatancy angle on the factor of safety for the slope stability analysis. The proposed method retain's the advantage of the upper bound method, which is simple and has no stress involvement in the calculation of the energy dissipation and the factor of safety. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献