我国黄土的微结构类型与震陷区域划分
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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。
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.
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.
引文
[1]Lu H Y,X WANG.The Plateau Monsoon Variation during the Past 130kyr Revealed by Loess Deposit at Northeast.Qinghai-Tibet(China)[J].Global and Planetary Change,2004,41:207-214.
[2]Ruddima W E,J E Kutzbach.Forcing of Late Cenozoic Northern Hemisphere Climate by Plateau Uplift in Southern Asian and American West[J].Journal of Geophysical Research,1989,94:18409-18427.
[3]Thomas S,A J Imon,Hua-yu LU.Sedimentation and Diagenesis of Chinese Loess Implications for the Preservation of Continuous,High Resolution Climate Records[J].Geology,2006,34(10):849-852.
[4]李吉均,文世宣,张青,等.青藏高原隆起的时代、幅度与形式的探讨[J].中国科学:B辑,1979,(6):608-616.LI Ji-jun,WEN Shi-xuan,ZHANG Qing,et al.Investigation on the Uplift Times,Amplitude and Styles of Tibet Plateau[J].Science in China:Series B,1979,6:608-616.(in Chinese)
[5]Tsoar H,K Pye.Dust Transportan the Question of Desert Loess Formation[J].Sedimentology,1987,34:139-153.
[6]Young R A,Wiersma J L.The Role of Rainfall Impact in Soil Detachment and Transport[J].Water Resoures,1973,9:1629-1635.
[7]H Wang,E Randall.Hughes Correlation of Climate Cycles in Middle Mississippi Valley Loess and Greenland ice[J].Geology,2003,2:179-182.
[8]刘东生,安芷生,朱炳泉.中国黄土的堆积与演化[C]∥第三届中国第四纪地质会议论文集.北京:中国科学院地球化学研究所,1979:1-31.LIU Dong-sheng,AN Zhi-sheng,ZHU Bing-quan.Accumulaiton and Evolution of Loess in China[C]∥Preceding of the Third Quaternary Geology Conference.Beijing:Geochemistry Institute,Chinese Academy of Sciences,1979:1-31.(in Chinese)
[9]Rea D K,S Hovan.Grain Size Distribution and Depositional Processes of the Mineral Component of Abyssal Sediments Lessons from the North Pacific[J].Pa1eoceanograph,1995,10:251-258.
[10]Sun D H,J Bloemendal,D K Rea.Grain-size Distribution Function of Polymodal Sediments in Hydraulic and Aeolian Environments and Nμmerical Partitioning of the Sedimentary Components[J].Sedimentary Geology,2002,152(3-4):263-277.
[11]朱慕仁.中国黄土地基工程分类体系及其定名商讨[C]∥中国黄土分类定名及其应用研讨会.西安:陕西人民教育出版社,1989.ZHU Mu-ren.China loess Foundation Engineering Classification system and name to discuss[C]∥China Loess ClassificationName and Application Workshop.Xi'an:Shaanxi People's Education Press,1989.(in Chinese)
[12]王永炎,林在贯.中国黄土的结构特征及物理力学性质[M].北京:科学出版社,1990.WANG Yong-yan,LIN Zai-guan.The China loess structure features and its physical and mechanical properties[M].Beijing:Science Press,1990.(in Chinese)
[13]赵景波.沉积理论与黄土高原环境演变[M].北京:科学出版社,2002:56-70.ZHAO Jing-bo.Sedimentary Theory and the Loess Plateau Environment Evolution[M].Beijing:Science Press,2002:56-70.(in Chinese)
[14]DENG Jin,WANG Lan-min,ZHANG Zhen-zhong,et al.Microstructure Characteristics and Forming Environment of Late Quaternary Period Loess in the Loess Plateau of China[J].Environmental Earth Sciences,Springer Berlin/Heidelberg,ISSN:1866-6280(Print),1866-6299(Online):2009.04,21.
[15]雷祥义.黄土高原南部晚更新世黄土地层划分、显微结构及力学性质特征[J].第四纪研究,1992,12(2):128-135.LEI Xiang-yi.Stratigraphic Division,Microfabric and Mechanical Characteristics of the Late Pleistocene Loess in the Southerin Loess Plateau of China[J].Quaternary Reseach,1992,12(2):128-135.(in Chinese)
[16]邓津,王兰民,张振中.黄土显微结构特征与震陷性[J].岩土工程学报,2007,27(4):542-548.DENG Jin,WANG Lan-min,ZHANG Zhen-zhong.Microstructure Characteristics and Seismic Subsidence of Loess[J].Chinese Journal of Geotechnical Engineering,2007,(4):542-548.(in Chinese)
[17]王兰民.黄土动力学[M].北京:地震出版社,2003:12-82.WANG Lan-min.Loess Dynamics[M].Beijing:Earthquake Press,2003:12-82.(in Chinese)
[18]张振中.黄土地震灾害预测[M].北京:地震出版社,1999:100-102.ZHANG Zhen-zhong.Loess Seismic Hazard Prediction[M].Beijing:Beijing Earthquake Press,1999:100-102.(in Chinese)
[19]樊成意,梁收运.甘肃省30年来崩滑灾害特征[J].西北地震学报,2011,33(B08):438-442.FAN Cheng-yi,LIANG Shou-yun.Characteristics of Collapse and Landslide Disasters in Gansu Province within 30Years[J].Northwestern Seismological Journal,2011,33,B08:438-442.(in Chinese)
[2]Ruddima W E,J E Kutzbach.Forcing of Late Cenozoic Northern Hemisphere Climate by Plateau Uplift in Southern Asian and American West[J].Journal of Geophysical Research,1989,94:18409-18427.
[3]Thomas S,A J Imon,Hua-yu LU.Sedimentation and Diagenesis of Chinese Loess Implications for the Preservation of Continuous,High Resolution Climate Records[J].Geology,2006,34(10):849-852.
[4]李吉均,文世宣,张青,等.青藏高原隆起的时代、幅度与形式的探讨[J].中国科学:B辑,1979,(6):608-616.LI Ji-jun,WEN Shi-xuan,ZHANG Qing,et al.Investigation on the Uplift Times,Amplitude and Styles of Tibet Plateau[J].Science in China:Series B,1979,6:608-616.(in Chinese)
[5]Tsoar H,K Pye.Dust Transportan the Question of Desert Loess Formation[J].Sedimentology,1987,34:139-153.
[6]Young R A,Wiersma J L.The Role of Rainfall Impact in Soil Detachment and Transport[J].Water Resoures,1973,9:1629-1635.
[7]H Wang,E Randall.Hughes Correlation of Climate Cycles in Middle Mississippi Valley Loess and Greenland ice[J].Geology,2003,2:179-182.
[8]刘东生,安芷生,朱炳泉.中国黄土的堆积与演化[C]∥第三届中国第四纪地质会议论文集.北京:中国科学院地球化学研究所,1979:1-31.LIU Dong-sheng,AN Zhi-sheng,ZHU Bing-quan.Accumulaiton and Evolution of Loess in China[C]∥Preceding of the Third Quaternary Geology Conference.Beijing:Geochemistry Institute,Chinese Academy of Sciences,1979:1-31.(in Chinese)
[9]Rea D K,S Hovan.Grain Size Distribution and Depositional Processes of the Mineral Component of Abyssal Sediments Lessons from the North Pacific[J].Pa1eoceanograph,1995,10:251-258.
[10]Sun D H,J Bloemendal,D K Rea.Grain-size Distribution Function of Polymodal Sediments in Hydraulic and Aeolian Environments and Nμmerical Partitioning of the Sedimentary Components[J].Sedimentary Geology,2002,152(3-4):263-277.
[11]朱慕仁.中国黄土地基工程分类体系及其定名商讨[C]∥中国黄土分类定名及其应用研讨会.西安:陕西人民教育出版社,1989.ZHU Mu-ren.China loess Foundation Engineering Classification system and name to discuss[C]∥China Loess ClassificationName and Application Workshop.Xi'an:Shaanxi People's Education Press,1989.(in Chinese)
[12]王永炎,林在贯.中国黄土的结构特征及物理力学性质[M].北京:科学出版社,1990.WANG Yong-yan,LIN Zai-guan.The China loess structure features and its physical and mechanical properties[M].Beijing:Science Press,1990.(in Chinese)
[13]赵景波.沉积理论与黄土高原环境演变[M].北京:科学出版社,2002:56-70.ZHAO Jing-bo.Sedimentary Theory and the Loess Plateau Environment Evolution[M].Beijing:Science Press,2002:56-70.(in Chinese)
[14]DENG Jin,WANG Lan-min,ZHANG Zhen-zhong,et al.Microstructure Characteristics and Forming Environment of Late Quaternary Period Loess in the Loess Plateau of China[J].Environmental Earth Sciences,Springer Berlin/Heidelberg,ISSN:1866-6280(Print),1866-6299(Online):2009.04,21.
[15]雷祥义.黄土高原南部晚更新世黄土地层划分、显微结构及力学性质特征[J].第四纪研究,1992,12(2):128-135.LEI Xiang-yi.Stratigraphic Division,Microfabric and Mechanical Characteristics of the Late Pleistocene Loess in the Southerin Loess Plateau of China[J].Quaternary Reseach,1992,12(2):128-135.(in Chinese)
[16]邓津,王兰民,张振中.黄土显微结构特征与震陷性[J].岩土工程学报,2007,27(4):542-548.DENG Jin,WANG Lan-min,ZHANG Zhen-zhong.Microstructure Characteristics and Seismic Subsidence of Loess[J].Chinese Journal of Geotechnical Engineering,2007,(4):542-548.(in Chinese)
[17]王兰民.黄土动力学[M].北京:地震出版社,2003:12-82.WANG Lan-min.Loess Dynamics[M].Beijing:Earthquake Press,2003:12-82.(in Chinese)
[18]张振中.黄土地震灾害预测[M].北京:地震出版社,1999:100-102.ZHANG Zhen-zhong.Loess Seismic Hazard Prediction[M].Beijing:Beijing Earthquake Press,1999:100-102.(in Chinese)
[19]樊成意,梁收运.甘肃省30年来崩滑灾害特征[J].西北地震学报,2011,33(B08):438-442.FAN Cheng-yi,LIANG Shou-yun.Characteristics of Collapse and Landslide Disasters in Gansu Province within 30Years[J].Northwestern Seismological Journal,2011,33,B08:438-442.(in Chinese)
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