农业经济用水量与我国农业战略节水潜力

在分析我国农业水资源利用现状基础上,从保障粮食安全和最大用水综合效益出发,提出了"农业经济用水量"的概念,分析了其内涵,提出了基于宏观水资源合理配置的"农业经济用水量"研究的理论基础及其相应技术基础,并从战略层面对我国未来可实现的农业经济用水量及其节水潜力进行了初步分析,为缓解我国农业用水与工业用水、生态用水之间的矛盾提供了有益的探索。

南沙群岛工程地质环境分区与珊瑚礁工程地质特性研究

Nansha Islands as sacred territory of China, containing abundant natural resources is the important area of sustaining development of Chinese people. Safeguarding and developing Nansha Islands has become one important part to develop ocean resource of China in 21 century. Engineering geological problems will be faced inevitably in the processes of engineering construction. Coral reef is a new kind of soil and rock and has special engineering characteristics. This doctoral dissertation researches deeply and systematically the regional engineering geology environmental properties and quality, engineering geological characteristics of coral reefs sand on the basis of synthetic analysis of hydrology, climate, geology, geomorphology and engineering field exploration information and combining the experimental data. 1. Put forward the division program of engineering geological environment of Nansha Islands according to the data of hydrology, geology and sediments, and also deeply study the properties of each division. Evaluate the quality of engineering geological environment by fuzzy mathematics and draw the evaluation map of quality of engineering geological environment. The research work provides background support of engineering geological environment to program of resource development in Nansha Islands. 2. Structures of coral reefs have been analyzed. The model of engineering geological zone has been proposed on the basis of geomorphologic zone and combining the strata and ocean dynamic environment. The engineering construction appropriation of each zone is praised. 3. The physical and mechanical properties of coral sands are researched. The results show that coral sands have high void ratio, non-regular shape, easy grain crushing and large compressibility. Shear-expansion takes place only at very low confining pressure and shear-contraction of volumetric strain occurs at higher confining pressure. Internal friction angle decreases with the increasing of confining pressure. The grain crushing property is the main factor influencing the mechanical characteristics. 4. A revised E-ν constitutive model is proposed which considers the change of internal friction angle with confining pressure, and parameter values are also determined. 5. The stability of Yongshu Reef by is analysed for the purpose of serving engineering struction. The process and mechanism of deformation and failure of foundation and slope is analyzed by finite-element method.