为研究冻融循环对青藏粉砂土屈服及强度特性的影响,进行环境冷却温度-5℃、室温下融化,不同冻融循环次数及围压下的饱和粉砂土的固结排水三轴剪切试验。结果表明:粉砂土在整个剪切过程中呈现出剪缩的特性,且其应力–应变关系为应变硬化...为研究冻融循环对青藏粉砂土屈服及强度特性的影响,进行环境冷却温度-5℃、室温下融化,不同冻融循环次数及围压下的饱和粉砂土的固结排水三轴剪切试验。结果表明:粉砂土在整个剪切过程中呈现出剪缩的特性,且其应力–应变关系为应变硬化型,冻融循环未改变粉砂土的应力–应变及体变型式。未冻融粉砂土的体积屈服面和剪切屈服面可分别用椭圆型曲线和过原点的线性函数进行描述。冻融循环未改变粉砂土屈服面的形状,且冻融粉砂的体积屈服函数及剪切函数与塑性应变和冻融循环次数的关系可用相应的幂函数形式进行表示。其抗剪强度随着法向应力的增大而增大,随着冻融循环次数呈现出先降低后升高的趋势。冻融循环后,粉砂的黏聚力由4.82 k Pa降至2.07 k Pa,而内摩擦角则由27.11°最低降至22.93°。根据不同冻融循环次数下粉砂强度随法向应力的变化规律,指出可用线性莫尔–库仑准则来描述其强度特性。展开更多
Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world.These soils typically have a loose honeycomb-type meta-stable structure that is susceptible t...Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world.These soils typically have a loose honeycomb-type meta-stable structure that is susceptible to a large reduction in total volume or collapse upon wetting.Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils.For this reason,collapse triggering mechanism for loess soils has been of significant interest for researchers and practitioners all over the world.This paper aims at providing a state-of-the-art review on collapse mechanism with special reference to loess soil deposits.The collapse mechanism studies are summarized under three different categories,i.e.traditional approaches,microstructure approach,and soil mechanics-based approaches.The traditional and microstructure approaches for interpreting the collapse behavior are comprehensively summarized and critically reviewed based on the experimental results from the literature.The soil mechanics-based approaches proposed based on the experimental results of both compacted soils and natural loess soils are reviewed highlighting their strengths and limitations for estimating the collapse behavior.Simpler soil mechanics-based approaches with less parameters or parameters that are easy-to-determine from conventional tests are suggested for future research to better understand the collapse behavior of natural loess soils.Such studies would be more valuable for use in conventional geotechnical engineering practice applications.展开更多
文摘为研究冻融循环对青藏粉砂土屈服及强度特性的影响,进行环境冷却温度-5℃、室温下融化,不同冻融循环次数及围压下的饱和粉砂土的固结排水三轴剪切试验。结果表明:粉砂土在整个剪切过程中呈现出剪缩的特性,且其应力–应变关系为应变硬化型,冻融循环未改变粉砂土的应力–应变及体变型式。未冻融粉砂土的体积屈服面和剪切屈服面可分别用椭圆型曲线和过原点的线性函数进行描述。冻融循环未改变粉砂土屈服面的形状,且冻融粉砂的体积屈服函数及剪切函数与塑性应变和冻融循环次数的关系可用相应的幂函数形式进行表示。其抗剪强度随着法向应力的增大而增大,随着冻融循环次数呈现出先降低后升高的趋势。冻融循环后,粉砂的黏聚力由4.82 k Pa降至2.07 k Pa,而内摩擦角则由27.11°最低降至22.93°。根据不同冻融循环次数下粉砂强度随法向应力的变化规律,指出可用线性莫尔–库仑准则来描述其强度特性。
基金the Chinese Scholarship Council,which funded her Joint Ph D research programthe support from Natural Sciences and Engineering Research Council of Canada(NSERC)for his research programsthe Chinese Ministry of Science and Technology for supporting his research program(grant No.2014CB744701)
文摘Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world.These soils typically have a loose honeycomb-type meta-stable structure that is susceptible to a large reduction in total volume or collapse upon wetting.Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils.For this reason,collapse triggering mechanism for loess soils has been of significant interest for researchers and practitioners all over the world.This paper aims at providing a state-of-the-art review on collapse mechanism with special reference to loess soil deposits.The collapse mechanism studies are summarized under three different categories,i.e.traditional approaches,microstructure approach,and soil mechanics-based approaches.The traditional and microstructure approaches for interpreting the collapse behavior are comprehensively summarized and critically reviewed based on the experimental results from the literature.The soil mechanics-based approaches proposed based on the experimental results of both compacted soils and natural loess soils are reviewed highlighting their strengths and limitations for estimating the collapse behavior.Simpler soil mechanics-based approaches with less parameters or parameters that are easy-to-determine from conventional tests are suggested for future research to better understand the collapse behavior of natural loess soils.Such studies would be more valuable for use in conventional geotechnical engineering practice applications.
