在长江河口两翼广泛分布第一硬土层(FHSL),研究其形成机制及工程地质特性对工程建设具有很好的指导意义。根据调查资料(钻孔935个,累计进尺42128 m)和试验资料,首次精确确认了长江河口北翼第一硬土层分布界线,研究了第一硬土层的形成年...在长江河口两翼广泛分布第一硬土层(FHSL),研究其形成机制及工程地质特性对工程建设具有很好的指导意义。根据调查资料(钻孔935个,累计进尺42128 m)和试验资料,首次精确确认了长江河口北翼第一硬土层分布界线,研究了第一硬土层的形成年代、粒度特征、地球化学特征、工程地质特性等。研究表明:第一硬土层形成年龄为20~11 ka B.P.(多个光释光和14C测年资料);硬土层含水率随深度的增加有增大的趋势,表明气候自下向上逐渐变凉和变干;第一硬土层的颗粒级配、粒度分布频率曲线、C-M沉积图等特征显示,第一硬土层主要由粉砂、极细砂和粘土粒级组成,样品的粒度频率曲线主要呈单峰分布,反映出物质沉积前所受搬运营力性质单一,土体颗粒沉积以均匀悬浮占绝对优势,沉积环境是一种相对稳定的低能环境。第一硬土层的发育受气候控制,大致可以分为3个阶段:第1阶段(20~15 ka B.P.)为沉积与成土交替作用时期,且以沉积作用为主,硬土层剖面厚度主要受该阶段控制,至末次盛冰期结束;第2阶段(15~11 ka B.P.)为暴露成土期,这时洪水不能形成越岸沉积,加积作用基本停止,硬土层厚度不再明显增加,已形成的第一硬土区域受到频繁变迁的分合河网的侵蚀切割,形成多条不规则古河道和台地,硬土层逐渐脱水成陆,经历了风化成壤的过程;第3阶段(11 ka B.P.至今)为淹埋期,随着全新世的到来,气候变暖,海平面不断上升,硬土层被其上覆的海相沉积层掩埋,成岩作用开始直到现今。土体易溶盐含量较高,为典型氯盐渍土类型,自下而上具有从低变高的趋势,为海相层覆盖硬土层以后成岩过程造成的。展开更多
Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,...Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.展开更多
文摘在长江河口两翼广泛分布第一硬土层(FHSL),研究其形成机制及工程地质特性对工程建设具有很好的指导意义。根据调查资料(钻孔935个,累计进尺42128 m)和试验资料,首次精确确认了长江河口北翼第一硬土层分布界线,研究了第一硬土层的形成年代、粒度特征、地球化学特征、工程地质特性等。研究表明:第一硬土层形成年龄为20~11 ka B.P.(多个光释光和14C测年资料);硬土层含水率随深度的增加有增大的趋势,表明气候自下向上逐渐变凉和变干;第一硬土层的颗粒级配、粒度分布频率曲线、C-M沉积图等特征显示,第一硬土层主要由粉砂、极细砂和粘土粒级组成,样品的粒度频率曲线主要呈单峰分布,反映出物质沉积前所受搬运营力性质单一,土体颗粒沉积以均匀悬浮占绝对优势,沉积环境是一种相对稳定的低能环境。第一硬土层的发育受气候控制,大致可以分为3个阶段:第1阶段(20~15 ka B.P.)为沉积与成土交替作用时期,且以沉积作用为主,硬土层剖面厚度主要受该阶段控制,至末次盛冰期结束;第2阶段(15~11 ka B.P.)为暴露成土期,这时洪水不能形成越岸沉积,加积作用基本停止,硬土层厚度不再明显增加,已形成的第一硬土区域受到频繁变迁的分合河网的侵蚀切割,形成多条不规则古河道和台地,硬土层逐渐脱水成陆,经历了风化成壤的过程;第3阶段(11 ka B.P.至今)为淹埋期,随着全新世的到来,气候变暖,海平面不断上升,硬土层被其上覆的海相沉积层掩埋,成岩作用开始直到现今。土体易溶盐含量较高,为典型氯盐渍土类型,自下而上具有从低变高的趋势,为海相层覆盖硬土层以后成岩过程造成的。
基金supported by the National Natural Science Foundation of China(42261028)the Chinese Academy of Sciences“Light of West China”Program for Western Young Scholars(23JR6KA027)+3 种基金the Science Foundation for Distinguished Young Scholars of Gansu Province(24JRRA167)the Key Research and Development Program on Ecological Civilization Construction of Gansu Province(25YFFA012)Gansu Provincial Science and Technology Plan Fund Project(24CXGA063)Scientific Research Projects on Ecological and Environmental Protection in Heilongjiang Province in 2023(Grant No.:HST2023ZR005)。
文摘Surface albedo,as one of the important properties of the underlying surface,has a significant impact on the surface energy balance in cold regions.However,due to the complexity of the factors affecting surface albedo,existing calculations still contain inaccuracies.Therefore,this study conducted surface albedo experiments on loess with different water contents and temperatures.By analyzing the surface albedo measurements of samples with varying temperature and water content levels,as well as the soil freezing characteristic curve(SFCC)and soil-water characteristic curve(SWCC)of loess,the study explores the influence of soil temperature and water content on the surface albedo of loess.The results indicate that both the temperature and water content of loess jointly affect surface albedo.During the process of albedo change,there exists a water content threshold that alters the trend of surface albedo.Soil temperature influences surface albedo by affecting the content of pore ice and liquid water within the soil.When the water content of loess is relatively low,the surface albedo decreases as the unfrozen water content decreases.However,this trend changes as the water content of loess increases.Additionally,a decrease in soil temperature lowers the moisture content threshold during the changes in surface albedo.This study provides a reference for exploring and determining the surface energy balance in cold regions under the background of warm and humid climates,as well as for establishing thermal calculation boundaries.
