發(fā)布時間：2018-10-26 07:18

【摘要】：基質(zhì)勢是驅(qū)動凍土中水分發(fā)生遷移的關(guān)鍵驅(qū)動力之一,但由于以往的技術(shù)限制,負(fù)溫下土體的基質(zhì)勢難以被直接測量,凍土基質(zhì)勢相關(guān)問題成為凍土水熱過程研究中的難題。利用可用于極端負(fù)溫條件下的pF meter基質(zhì)勢傳感器,針對青藏紅黏土、蘭州粉土以及張掖細(xì)砂這三種不同粒徑級配的土體,分別從粒徑大小和初始含水量的角度,通過室內(nèi)試驗,研究了土體凍結(jié)與融化過程中基質(zhì)勢、未凍水量以及溫度三者之間動態(tài)變化的關(guān)系。結(jié)果表明:凍土中的冰晶體對基質(zhì)勢和未凍水量的影響類似于融土中的氣體,而冰晶體的含量又與土體溫度相關(guān);由粒徑級配決定的比表面積對凍土基質(zhì)勢存在著決定性的影響;此外,初始含水量的多少對凍土基質(zhì)勢也存在與融土類似的影響。研究成果揭示了負(fù)溫凍土中未凍水的數(shù)量與能量狀態(tài)隨凍結(jié)與融化過程的變化關(guān)系,為研究凍土中水分在基質(zhì)勢驅(qū)動下的遷移過程提供了理論基礎(chǔ)和試驗支撐。
[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.
【作者單位】： 中國科學(xué)院西北生態(tài)環(huán)境資源研究院凍土工程國家重點實驗室;中國科學(xué)院大學(xué);蘭州理工大學(xué)土木工程學(xué)院;
【基金】：國家自然科學(xué)基金項目(41471061和41690144) 凍土工程國家重點實驗室自主課題(SKLFSE-ZT-22) 中科院寒旱所STS項目(HHS-TSS-STS-1502)共同資助
【分類號】：TU445
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本文編號：2294981