基于pF meter传感器的土体冻融过程中基质势与未冻水量关系研究
发布时间：2018-10-26 07:18
【摘要】：基质势是驱动冻土中水分发生迁移的关键驱动力之一,但由于以往的技术限制,负温下土体的基质势难以被直接测量,冻土基质势相关问题成为冻土水热过程研究中的难题。利用可用于极端负温条件下的pF meter基质势传感器,针对青藏红黏土、兰州粉土以及张掖细砂这三种不同粒径级配的土体,分别从粒径大小和初始含水量的角度,通过室内试验,研究了土体冻结与融化过程中基质势、未冻水量以及温度三者之间动态变化的关系。结果表明:冻土中的冰晶体对基质势和未冻水量的影响类似于融土中的气体,而冰晶体的含量又与土体温度相关;由粒径级配决定的比表面积对冻土基质势存在着决定性的影响;此外,初始含水量的多少对冻土基质势也存在与融土类似的影响。研究成果揭示了负温冻土中未冻水的数量与能量状态随冻结与融化过程的变化关系,为研究冻土中水分在基质势驱动下的迁移过程提供了理论基础和试验支撑。
[Abstract]:The matrix potential is one of the key driving forces to drive the moisture migration in frozen soil. However, due to the technical limitation in the past, it is difficult to directly measure the matrix potential of the soil under negative temperature, and the related problems of matrix potential in frozen soil become a difficult problem in the study of the hydrothermal process of frozen soil. Based on the pF meter matrix potential sensor which can be used in extreme negative temperature conditions, the laboratory tests were carried out on three different gradation soils of Qinghai-Tibet red clay, Lanzhou silt and Zhangye fine sand from the angle of particle size and initial water content, respectively. The dynamic changes of matrix potential, unfrozen water and temperature in the process of freezing and melting of soil were studied. The results show that the effect of ice crystals on matrix potential and unfrozen water is similar to that of gases in thawed soil, and the content of ice crystals is related to soil temperature. The specific surface area determined by particle size gradation has a decisive effect on the matrix potential of permafrost, in addition, the amount of initial water content has a similar effect on the matrix potential of frozen soil as well as that of thawed soil. The research results reveal the relationship between the amount and energy state of unfrozen water in negative frozen soil with the process of freezing and melting, and provide a theoretical basis and experimental support for studying the migration process of water in frozen soil driven by matrix potential.
【作者单位】： 中国科学院西北生态环境资源研究院冻土工程国家重点实验室;中国科学院大学;兰州理工大学土木工程学院;
【基金】：国家自然科学基金项目(41471061和41690144) 冻土工程国家重点实验室自主课题(SKLFSE-ZT-22) 中科院寒旱所STS项目(HHS-TSS-STS-1502)共同资助
【分类号】：TU445
，
本文编号：2294981
[Abstract]:The matrix potential is one of the key driving forces to drive the moisture migration in frozen soil. However, due to the technical limitation in the past, it is difficult to directly measure the matrix potential of the soil under negative temperature, and the related problems of matrix potential in frozen soil become a difficult problem in the study of the hydrothermal process of frozen soil. Based on the pF meter matrix potential sensor which can be used in extreme negative temperature conditions, the laboratory tests were carried out on three different gradation soils of Qinghai-Tibet red clay, Lanzhou silt and Zhangye fine sand from the angle of particle size and initial water content, respectively. The dynamic changes of matrix potential, unfrozen water and temperature in the process of freezing and melting of soil were studied. The results show that the effect of ice crystals on matrix potential and unfrozen water is similar to that of gases in thawed soil, and the content of ice crystals is related to soil temperature. The specific surface area determined by particle size gradation has a decisive effect on the matrix potential of permafrost, in addition, the amount of initial water content has a similar effect on the matrix potential of frozen soil as well as that of thawed soil. The research results reveal the relationship between the amount and energy state of unfrozen water in negative frozen soil with the process of freezing and melting, and provide a theoretical basis and experimental support for studying the migration process of water in frozen soil driven by matrix potential.
【作者单位】： 中国科学院西北生态环境资源研究院冻土工程国家重点实验室;中国科学院大学;兰州理工大学土木工程学院;
【基金】：国家自然科学基金项目(41471061和41690144) 冻土工程国家重点实验室自主课题(SKLFSE-ZT-22) 中科院寒旱所STS项目(HHS-TSS-STS-1502)共同资助
【分类号】：TU445
，
本文编号：2294981
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