Behaviour of an outward inclined-vertical framed retaining wall of an excavation

Acta Geotechnica - A new excavation retaining structure, referred to as an outward inclined-vertical framed retaining wall (OIVFRW), has been developed and adopted in practice. This retaining...     

二维滞弹性非静力平衡云模式第二部分──中低空风切变对云微物理过程的影响

本文运用已建立的二维时变云模式［1］，就中低空风垂直切变对对流和云微物理过程的影响进行了模拟研究。为此设计了五种方案进行了对比试验。结果表明：中低空风切变较小时，容易爆发对流；中低空切变不超过某一值时，对流发展缓慢，但最终会爆发强对流；一旦中低空风切变超过某一值时，则对流发展不起来。另一方面，中低空风切变可加强各云微物理过程及地面降水量。     

Analysis of social vulnerability of residential community to hazards in Tianjin,China

Flood management consists many aspects such as hazard assessment, vulnerability assessment, exposure assessment, risk assessment, early warning system, damage assessment as well as risk mitigation planning. Conventional flood management are depending on the ground based monitoring of rainfall and river discharge. Many parts of the world are not covered by these sensor networks in one hand and these ground based systems are costly. Most of the tropical countries have high flood risk and low financial and institutional capacity to afford ground based system. While conventional flood management is time and cost intensive, spaceborne remote sensing provides timely and low-cost data in comparison to field observation, and is the obvious choice for most developing countries affected by flooding. Many aspects of flood management are being aided with the advancement of remote sensing technology. More precise and near real time flood detection, lead time in flood early warning system, accurate and advance inputs of hydrological models are now blessed by space technology. Many methods and approaches have been developed to overcome the constrains in the application of spaceborne remote sensing in flood management. Application of satellite remote sensing in flood hazard assessment is well documented, however, the application of space technology in other aspects of the flood management is also promising. Therefore, this review paper focuses on the applicability of spaceborne remote sensing and in most of the aspects in flood management.

     

Seasonal change of ice algal and phytoplankton assemblages in the Nella Fjord near Zhongshan Station, East Antarctica

The ice algal and phytoplankton assemblages were studied from Nella Fjord near Zhongshan Station, East Antarctica from April 12 to December 30, 1992. Algal blooms occurred about 3 cm thick on the bottom of sea ice in late April and mid November to early December respectively, and a phytoplankton bloom appeared in the underlying surface water in mid December following the spring ice algal bloom. The biomass in ice bottom was 1 to 3 orders of magnitude higher than that of surface water. Amphiprora kjellmanii, Berkeleya sp., Navicula glaciei, Nitzschia barkelyi, N. cylindrus /N. curta, N. lecointei and Nitzschia sp. were common in the sea ice temporarily or throughout the study period. The biomass in a certain ice segment was decreased gradually and the dominant species were usually succeeded as the season went on. Nitzschia sublineata and Dactyliosolen antarctica were two seasonal dominant species only observed in underlying water column. The assemblages between bottom of ice and underlying surface water were different except when spring ice algae bloomed. The evidence shows that the ice algal blooms occurred mainly by in situ growth of ice algae, and the phytoplankton bloom was mostly caused by the release of ice algae.     

Structural Setting of Strong Earthquakes in the Huabei Area of China

— Using P and S arrival times, which occurred within the Huabei seismic network, we carried out a tomographic inversion and compared results with the earthquake catalogue of the last 1000?years in the area. The results are as follows:¶1) The hypocenters of most of the strong shocks are distributed in the transitional zones between high- and low-velocity areas in the crust, especially at edges of high-velocity blocks.¶2) Strong shocks predominantly lie above low-velocity blocks, or in transitional zones between low- and high-velocity areas, in the lower crust.¶3) The tectonic settings for the Tangshan and the Sanhe-Pingu earthquakes are similar. Both are not known near large fault belts, and in zones with a sharp lateral velocity gradient.¶4) The Ninghe, Tangshan and Luanxia earthquakes are located in high-velocity blocks that differ in size and depth. This difference can explain the focal depth distribution of the Tangshan earthquake sequence, i.e., earthquakes are shallower in the northeastern Luanxian area but deeper in the southwestern Ninghe area.     

Spectral analysis of vehicle pollutants at traffic intersection in Hong Kong

This paper reports an investigation on the periodic variation of pollutant levels at a typical traffic intersection of Hong Kong. Carbon monoxide, carbon dioxide and particulate matters (PM _x ) were measured respectively and the measured data show periodic variations with the traffic signal intervals. The power spectral density (PSD) approach was used to inspect the trends and periodic oscillations of measured pollutants. Singular spectrum analysis was applied to decompose the measured data into statistically significant non-linear trends and oscillations in the process. From the results, most of the trends tend to increase due to the upcoming rush hour during the experiment. In addition, all the oscillations changed regularly with a period of 136?s, which is coincident with the traffic signal period and the frequency calculated by using PSD. The trends, together with the oscillations, collectively explain the most percentage of the variability of the data in the time series and provide the principal components of the data in understanding the periodic variation of the pollutant concentration. It can be deduced that vehicle emission is the major contributor to the air pollution in downtown area and pedestrians should be more alerted when crossing the busy traffic intersections.     

塔里木盆地牙哈-英买力地区寒武系-奥陶系碳酸盐岩储层成因类型、特征及油气勘探潜力

牙哈—英买力地区是塔北隆起上的主要油气富集区,古潜山风化壳型储层的观点一直主导着该地区寒武系—奥陶系碳酸盐岩油气勘探的思路。但储层精细描述揭示了牙哈—英买力地区除古潜山风化壳型储层外,还发育有暴露浅滩型、层间古岩溶型、白云岩型储层。其中位于古潜山面之下经风化作用改造的白云岩型储层是最有勘探价值的,勘探成功率高。其次是暴露浅滩型储层,油藏类型有早成藏残留型和晚成藏型。暴露浅滩型、层间古岩溶型和白云岩型储层也是很有勘探价值的储层类型。早成藏型原生油气藏,位于寒武系—奥陶系与志留系呈假整合接触的地区,与古潜山无关。古潜山风化壳型储层可以形成晚成藏型油气藏,但目前试油结果均为水层,值得进一步探索。     

双峰县金坑冲金矿地质特征及找矿前景

本文概述了金坑冲金矿地质特征,并对其矿化规律作了总结。在此基础上,依据地质类比与土壤地球化学测量成果,指出王家湾一丫头山一带,是找石英脉一蚀变岩型金矿的远景区。     

四川紫色土退化的分类与分区

四川紫色土耕地面积406.1万公顷,占全省耕地面积的36.5％,属全省农业生产的主体区域。四川紫色土普遍退化。退化分为物理性(含构造性)、化学性、营养性三类。用模糊综合评判方法,评价了四川(主要为盆地丘陵区)紫色土退化的程度和状况。同时又建立了退化紫色土的分区原则,将四川紫色土退化分布区域划分为6个退化亚区,10个退化小区。     

Environmental impact of drainage of Dianzi Iron Mine on the groundwater system of the Dawu Water Supply Base

Due to growing water extraction for industry and agriculture, the Dawu Water Supply Base, in the east of Zibo, China, has been in a state of serious over-extraction. It will also be affected by the deep drainage of the Dianzi Iron Mine, which will be exploited in 2005. As to the environmental impact on the groundwater system of the Dawu Water Supply Base is concerned, this paper makes a systematic study about the influence of the mine draining on the water-supply environment of the Dawu Water Supply Base by using the numerical model of groundwater system. The result shows that the groundwater level will have an additional drawdown of 1.2–1.8 m/yr by the mine draining alone. The numerical analysis results indicate that the optimal model for determining the best extraction plan is the solution for the contradiction between water supply and water drainage.