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11.
发展互花米草开发华南热带海滩   总被引:11,自引:0,他引:11  
互花米草是禾本科多年生高秆型草本植物,原产北美洲大西洋海岸,70年代末引入我国,本文在大量试验基础上,对互花米草在华南热带海滩的生长适应性,生物量和收获量及其在促淤造陆,改良土壤等方面作了论述,并对互花米草的抗污染作用和作为饲料,饵料等的经济作用也进行了定量分析,认为互花米草在华南热带海滩具有广阔的开发应用前景。  相似文献   
12.
对煤中锗矿化若干问题的思考——以临沧锗矿为例   总被引:8,自引:0,他引:8  
胡瑞忠  毕献武 《矿物学报》1997,17(4):364-368
本文在综述煤中锗矿化国内外研究现状的基础上,以临沧锗矿为例,深入讨论了在煤系地层中形成超大型独立锗矿床的特殊条件。结果表明,煤是锗成矿极有利的围岩,煤能否富集锗主要取决于有无富锗流体与煤相互作用。  相似文献   
13.
J. Bi  C. Yu 《GeoJournal》1996,40(1-2):9-15
Considering the concept of cost-of-remediation (COR), water indices such as a quality index, a hazard index and a risk index are established to describe the water pollution in China. Sustainability analysis associated with water pollution is also addressed. The spatial variations of these indices in different provinces and the related reasons are considered. It is obvious that water pollution is mainly caused by the economic development, though economic development does not always bring higher risks.  相似文献   
14.
This paper expounds the quantitative tectonic indicators and some qualitative indicators of large earthquakes in the coast areas of Fujian, Guangdong, Taiwan and Hainan. The main quantitative indicators include uplift amplitude of the Moho, Quaternary and Late Holocene coasts. The paper also gives a brief account of the research method on quantitative indicators of surface uplifted zones. Taiwan is a famous neotectonic zone and an area of large earthquakes in the world. There is only one large-earthquake area in each of Fujian, Guangdong and Hainan Provinces. Along the coast large earthquake areas there are certainly many remains of crustal activity. Among these remains, coast activity, taking the sea level as the accurate marker horizon, can determine not only the amplitude of coastal elevation and subsidence in a certain period, but also the cycle and rate of positive or negative movements.  相似文献   
15.
1997年7月19日影响北京地区的暴雨个例分析   总被引:7,自引:3,他引:7  
毕宝贵  李晓莉  李泽椿 《气象》2004,30(6):18-23
针对在实际业务预报中经常遇到的北京地区降水的两种特殊性(明显天气系统移来时,北京地区降水明显比周围偏多或偏少),选取一个实例利用中尺度非静力模式(MM5)对降水比周围偏多情况进行了高分辨率数值模拟和敏感性试验。结果表明,该模式比较成功地模拟了此次天气过程及其相关的中尺度系统的发生发展,凝结潜热对天气过程的发生发展有重要作用,而地形在天气过程中也起着主要作用,低层潜在不稳定能量的储备和输送是暴雨发生不可缺少的条件。  相似文献   
16.
Water percolation and flow processes in subsurface geologic media play an important role in determining the water source for plants and the transport of contaminants or nutrients, which is essential for water resource management and the development of measures for pollution mitigation. During June 2013, the dynamics of the rainwater, soil water, subsurface flows and groundwater in a shallow Entisol on sloping farmland were monitored using a hydrometric and isotopic approach. The results showed that effective mixing of rainwater and soil water occurred in hours. The rebound phenomenon of δD profiles in soils showed that most isotope‐depleted rainwater largely bypassed the soil matrix when the water saturation in the soil was high. Preferential‐flow, which was the dominant water movement pattern in the vadose zone, occurred through the whole soil profile, and infrequent piston‐flow was mainly found at 20–40 cm in depth. The interflow in the soil layer, composed of 75.2% rainwater, was only generated when the soil profile had been saturated. Underflow in the fractured mudrock was the dominant flow type in this hillslope, and outflow was dominated by base flow (groundwater flow) with a mean contribution of 76.7%. The generation mechanism of underflow was groundwater ridging, which was superimposed upon preferential‐flow composed mainly of rainwater. The quick mixing process of rainwater and soil water and the rapid movement of the mixture through preferential channels in the study soil, which shows a typical bimodal pore size distribution, can explain the prompt release of pre‐event water in subsurface flow. Water sources of subsurface flows at peak discharge could be affected by the antecedent soil water content, rain characteristics and antecedent groundwater levels. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
17.
In mountainous areas, channelized rock avalanches swarm downslope leading to large impact forces on building structures in residential areas. Arrays of rock avalanche baffles are usually installed in front of rigid barriers to attenuate the flow energy of rock avalanches. However, previous studies have not sufficiently addressed the mechanisms of interaction between the rock avalanches and baffles. In addition, empirical design approaches such as debris flow (Tang et al., Quat Int 250:63–73, 2012), rockfall (Spang and Rautenstrauch, 1237–1243, 1988), snow avalanches (Favier et al., 14:3–15, 2012), and rock avalanches (Manzella and Labiouse, Landslides 10:23–36, 2013), which are applied in natural geo-disasters mitigation cannot met construction requirements. This study presents details of numerical modeling using the discrete element method (DEM) to investigate the effect of the configuration of baffles (number and spacing of baffle columns and rows) on the impact force that rock avalanches exert on baffles. The numerical modeling is firstly conducted to provide insights into the flow interaction between rock avalanches and an array of baffles. Then, a modeling analysis is made to investigate the change pattern of the impact force with respect to baffle configurations. The results demonstrate that three crucial influencing factors (baffle row numbers, baffle column spacing, and baffle row spacing) have close relationship with energy dissipation of baffles. Interestingly, it is found that capacity of energy dissipation of baffles increases with increasing baffle row numbers and baffle row spacing, while it decreases with increasing baffle column spacing. The results obtained from this study are useful for facilitating design of baffles against rock avalanches.  相似文献   
18.
阎春波  李姜丽  赵璧  程龙 《地质论评》2021,67(6):67112006-67112006
本文系统总结了湖北宜昌地区省级及省级以上地质遗迹资源,认为该地区地质遗迹分布规律主要可概括为两个方面,一是受控于地形和河流的综合作用,以各类地貌景观遗迹为特点;二是各个地质时代地层剖面齐全,古生物化石产地聚集。其中可归类为世界级地质遗迹点为5个,均以“古生物化石”为核心,分别为三峡地区埃迪卡拉生物群、长阳寒武纪清江生物群、黄花场中奥陶统大坪阶“金钉子”、王家湾上奥陶统赫南特阶“金钉子”和远安三叠系南漳—远安动物群。立足于此,文中首次详细总结了这些地质遗迹点的化石代表、科学及科普意义,并从地质遗迹自身保护和应用方式、地质遗迹载体、地学研学、地质文化的传播和文创科普产品5个方面对古生物地质遗迹资源的发展模式进行了详细探讨,从而为宜昌地区全域地质遗迹开发和旅游提供新思路。  相似文献   
19.
“可持续社会指数”的研究综述与展望   总被引:1,自引:0,他引:1  
正确评价和监测区域可持续发展水平,是实现2030年可持续发展目标的关键参考.随着观测手段和计算机技术的蓬勃发展,以指标观测和指数表达为基础的“指标时代”的到来为研究区域可持续发展水平提供了一个思路.“可持续社会指数”是全要素的综合评价,可以综合衡量国家尺度的可持续发展程度,并长期监测.从理论研究、指标框架和方法论的角度详细介绍了“可持续社会指数”,从对“可持续社会指数”的指标选取和指数计算方面的局限和改进两个方面,对其相关研究进行综合梳理.最后,提出了未来可能应用的研究方向.  相似文献   
20.
Chian  S. C.  Bi  J. 《Acta Geotechnica》2021,16(4):1127-1145

In nature, soils are often composed of varying amounts of clay, silt and sand. Variation of the percentage of these compositions can affect the final strength of the soils when stabilised with cement. In this study, focus was placed on clayey soils with different gradation of sand impurities up to 40% in mass. An extensive study of such clayey soils treated with cement was investigated. For the results, it is noted that water:cement ratio was a major influence of strength development of cement-treated clayey soils. In contrast, the soil:cement ratio was found to have minor effects on the strength development. The presence of sand impurities has a significant reduction on the strength development of the cement-treated clayey soil mixture due to more free water available for hydration. The use of free-water:cement ratio is adopted which was shown to be capable of adjusting for such change in amount of free water and water holding capacity of the clay which is determined with Atterberg’s liquid limit tests. The effects of gradation (fine, coarse and well-graded) of the sand impurities were found to affect strength development minimally, owing to similarities in their liquid limits when mixed with clay. Ordinary Portland cement (OPC)-treated clayey soils produced a more rapid gain in strength but lower final strength at 28 days of curing as compared with Portland blast furnace cement (PBFC). This is found to be persistent for different gradation of sand impurities. A linear correlation can be established based on the log of the unconfined compressive strengths developed at different curing age, with slopes of these linear trends found to be similar for PBFC and OPC-treated clayey soil specimens. Finally, a strength prediction model comprising of these findings is developed. The parameters adopted in this model coincide with values proposed by past studies, thereby validating the robustness of the model. The practical benefits from this study offer a quality control scheme to forecast long-term performance of cement-treated clayey soils as well as optimise cement dosage in cement stabilisation to produce a more cost-effective and less environmental-invasive usage of the technology in geotechnical applications.

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