【摘要】 对比我国中西部成土年代相近的浅层风成黄土(不考虑地形地貌),针对不同成土环境下微观结构及其震陷性大小,初步将中西部黄土的微结构类型划分为五类:Ⅰ,近砂源快速降砂微结构;Ⅱ,强降尘弱成壤微结构;Ⅲ,冷干慢速降尘弱成壤微结构;Ⅳ,中湿成壤微结构;Ⅵ,温湿成壤微结构。微结构类型对于震陷性等工程性质分析有借鉴作用,具体体现在颗粒大小、粒径分布、排列方式,颗粒之间的胶结程度、接触方式等。通过分析黄土地区气候变化引起的地域性微观结构类型差异,区域性微观结构的气候形成机制来研究黄土的致灾特征,进一步获得黄土地区土层微结构的地域性差别导致的震陷变形强弱信息。这对于黄土建筑工程场地的设计以及提出针对性的防护措施有重要意义。更多还原

【Abstract】 Loess forms from dust being deposited over the millennia under varied climatic conditions in the Loess Plateau of China through climate evolution.Influenced by monsoon,rainfall,temperature,dust characteristics,and so on.By forming under different regional climatic conditions,loess exhibits a wide range of microstructural morphologies.From its microscopic structure,we can obtain datum on particle size distribution,pore size distribution,and cementing quality,which can more fully elucidate the formation of regional loess.Because the microstructural characteristics of loess are directly related to dynamic deformation,strength,and arrangement mode,the features of loess microstructural formation types and regional deposition by particle size can be studied by an intuitive method in seismic hazard analysis.In contrast,in similar Midwestern shallow eolian loess soils(not considering landform),analysis of the microstructure under different soil environments is by sediment size.Western loess-forming microstructures are divided into five categories:(1)near a sand source,formed by fast sand dropping;(2)weakly formed by strong sand dropping;(3)formed in cold weather by slow sand dropping;(4)weakly formed in warm,damp weather;and(5)strongly formed in warm,damp weather.Differences in particle size,particle size distribution,particles between,degree of consolidation,contact,and so on,determine the microstructure types in the sediments,which have important effects on engineering properties.By analyzing the formation mechanism of loess by study of the microstructure in regional climates,and then further by analyzing the loess area,the regional differences in soil microstructure can determine the sediment deformation(either strong or weak).Such information is useful in building engineering site design and in determining corresponding protective measures.更多还原