Hydro-mechanical experiments on suffusion under long-term large hydraulic heads

The long-term large hydraulic head in flood season is the main cause of suffusion failure or dam break, while the suffusion failure mechanism in this case has not been specially studied. First, a newly designed hydro-mechanical coupling suffusion apparatus was introduced. Second, two short-term suffusion experiments under different confining pressures were carried out to determine the suitable large hydraulic heads. Finally, four experiments on suffusion under long-term large hydraulic heads and different confining pressures were performed to investigate the influences of the long-term large hydraulic heads and the confining pressures on the evolution of suffusion. The results indicate that: (1) The signs of suffusion failure in the short-term experiments are the sudden decrease in hydraulic gradient and the sharp increase in eroded mass. While the flow rate in the long-term experiments appearing suffusion failures increases rapidly with the decrease in hydraulic gradient. (2) The suffusion failure in the long-term large hydraulic head experiment is more likely to happen and much more serious than that in the short-term experiment. The long-term large hydraulic head can reduce the suffusion failure hydraulic gradient significantly and increase the eroded mass dramatically. The results gained here provide a deeper understanding on the suffusion failure caused by the rapid increase in the high water level upstream the hydraulic earth structures in flood season.     

西北黄土地区地铁深基坑工程监测的关键技术

根据西北黄土地区第一条地铁——西安地铁近四年地铁基坑工程的监测经验,提出了基坑工程监测的主要内容、作用及其常用监测手段,介绍了轴力监测关键技术;测斜仪量测墙体位移关键技术;地裂缝段地表监测点布设的关键技术;盾构地表监测作用、监测项目、地层移动特征;监测报警注意事项。其中着重分析了黄土地区常用的内支撑形式——钢支撑监测的注意事项及常见异常测量数据的出现原因,提出温度对其测量结果的影响不可忽略。     

西藏改则盆地渐新统—中新统康托组沉积相特征

改则盆地地处青藏高原羌塘地层区,研究程度较低。通过对西藏改则盆地新近系康托组沉积特征和沉积岩相的详细研究,共划分出3类沉积相:扇三角洲相、湖泊三角洲相和湖泊相,整体表现为自下向上沉积物粒度由粗到细、水深逐渐增大的退积序列。综合区域地质特征及古流向分析认为,改则盆地渐新世—中新世的沉积演化可大致分为2个阶段:盆地初始裂陷阶段和盆地稳定沉积阶段。康托组剖面沉积相的研究有助于了解改则盆地渐新世—中新世的沉积演化。     

内蒙古银额盆地额济纳旗赛汉陶来地区石炭系 —二叠系煤层的发现及其意义

在对赛汉陶来地区19口石油及煤田钻井地层岩性组合特征分析的基础上,总结了中生代不同构造单元的地层分布特征、含煤层段岩性特征及煤岩物理化学特征。含煤层段岩性组合为沉火山碎屑岩或再搬运的沉火山岩、泥岩夹煤层,具有典型裂谷盆地沉积特征。该套地层横向分布稳定,不同构造单元之间可进行对比,单井平均可采煤层的厚度为4.77m。煤岩演化程度较低,为不粘煤。含煤层段沉火山角砾岩获得的锆石年龄为295.0Ma±1.3Ma~303.4Ma±2.8Ma,对应地层为上石炭统—下二叠统干泉组。银额盆地赛汉陶来地区石炭系—二叠系含煤地层的发现不仅指示了良好的煤炭资源前景,并且对石炭纪—二叠纪盆地构造演化、沉积体系,以及石炭系—二叠系沉积埋藏史等基础地质问题的研究具有重要意义。     

巢湖地区楚歌岭剖面下三叠统和龙山组碳同位素变化特征及其意义

碳同位素在海相碳酸盐岩研究中日益受到重视,成为重大地质事件识别与解释、地层划分与对比的重要手段之一.通过对巢湖地区楚歌岭剖面早三叠世地层碳同位素研究,显示Smithian\Spathian界线处碳同位素的快速正漂具有全球性特征,可以作为地层划分对比的良好标志;而且这一变化特征反映一次海洋生产力暴发事件,与海洋环境突变和灾后生物的复苏关系密切,为早三叠世海洋生态系统灾后重建过程的恢复提供了重要线索.     

沉积盆地深层地下卤水资源量评价之若干探讨

沉积盆地深层地下卤水(包括富钾卤水)处于深埋封闭和无补给状态; 卤水具有很高的测压水头, 天然条件下处于停滞状态, 不同储卤构造之间无水力联系; 具有多个平行叠置的储卤层, 不同储卤层之间无水力联系; 储卤层空隙性和渗透性差, 卤水主要富集于背斜、裂隙带和断层裂隙带; 卤水水化学和物理特性在短期内比较稳定; 卤水储存资源量较大, 在开采条件下卤水资源逐渐减少趋于衰竭。本文在分析总结沉积盆地深层地下卤水资源量评价的现状和卤水特征的基础上, 讨论和阐明深层地下卤水资源评价中的若干问题, 包括深层卤水资源量的类型和评价方法的选取、储卤层计算范围和边界的概化处理、渗透性分区和卤水密度影响的处理、测压水头的换算、钻井预测水头降深的确定等, 目的在于提高深层地下卤水资源量评价计算的精度。     

Thermal plumes and turbulence spectra in the atmospheric boundary layer

Experimental observations on the temperature and wind fields above flat grassy terrain have been obtained with an instrumented 92-m tower during intervals of strong insolation about midday. The turbulence characteristics of the air confirm that free convection prevailed at heights between 16 and 48 m, with some tendency for departure at higher levels. The spectra of temperature and vertical velocity contain gaps at wave numbers in the range 0.01–0.025 m^–1. These are attributed to natural thermal plumes that act as sources of extra energy input to the Kolmogorov-Obukhov-Corrsin scheme of turbulence in or at the low-wave number limit of the inertial subrange. Modified forms of the K-O-C spectral laws for thermally unstable air are derived which agree with the observed spectra over the whole range of wave numbers examined, and which contain the spectral gap at wave numbers corresponding to the thermal plume diameters.     

Impacts of beach closures on perceptions of swimming-related health risk in Orange County, California

Following a major beach closure due to bacterial contamination, a survey of beachgoers was conducted in Huntington Beach, California in 1999 to assess perceived health risk from swimming. Responses were compared to those of beachgoers at the unaffected Laguna Main Beach. No significant differences were found in risk perception. Respondents were aware of the closures (83%), yet the majority (83%) felt the water was safe for swimming. Proximity of residence to the beach was strongly associated with closure awareness (Spearman's rho=0.427, p<0.0001). Although 83% of respondents felt that water quality was important in deciding to go to the beach, only 25% of respondents who did not plan to swim cited pollution or contamination as a reason not to swim. Most respondents (70%) trusted local health agency officials' decisions about when to open/close beaches. Surveyed beach visitors were likely to bathe (84%) and were not highly concerned with swimming-related health risks.     

Spatial analyses of factors affecting household structure in Chinese cities: The case of three-generation lineal households

Household structure is an important aspect of family change during China’s modernization process. Existing literature has demonstrated significant associations between various factors and household structure, but the spatial variation in these relationships has not been examined. Using the 2010 Chinese population census data and geographically weighted regression (GWR) model, this study explored the spatial patterns of three-generation lineal households, a functionally important household type in China, and its influencing factors. There was significant heterogeneity in the distribution of three-generation lineal households. Socioeconomic, demographic, and cultural factors were all significantly related to the proportion of three-generation lineal households, but the relationships are place-specific in terms of direction and magnitude. These results suggest that the distribution of Chinese household structures cannot be explained by a single framework of family modernization theory but is determined by the interplay of various local characteristics. Especially, population migration plays an equally important role in affecting household structure than socioeconomic development in China. This work contributes to the family literature by highlighting the spatial heterogeneity in the impact of varying factors on household structure. Beyond the classic modernization theory, it sets a contextualized framework for understanding how Chinese household change in response to the rapid social transformation.     

Correlations between morphology and other galaxy parameters at different environmental density levels

Using two volume-limited samples above and below the value of $M_{r}^{ *}$ constructed from the Main galaxy sample of the Sloan Digital Sky Survey Data Release 8 (SDSS DR8), we investigate correlations between galaxy morphology and star formation rate (SFR), specific star formation rate (SSFR) and stellar mass at different environmental density levels. For each sample, three subsamples at both density extremes and at the median density are selected. We found that examining either of our two volume-limited Main samples leads to the same conclusion: at different environmental density levels, SFR, SSFR and stellar mass are strongly correlated with galaxy morphology, which shows that SFR, SSFR and stellar mass of a galaxy depend on its environment as well as its morphology.