兰州黄土在冻融过程中水热输运实验研究

实验表明，当上边界面温度按正弦变化，下边界面温度保持某一固定值时，冻结均匀的兰州黄土融化后，相变界面附近的含水量明显增大。同样，对初始均匀融化的兰州黄土试样，经冰融循环作用后，冰土层内最大融化深工附近的含水量大于附近区域的含水量。试样内水分在冻融作用下的这种积累特征，与天然情况下多年冻土上限附近出现的水分富积现象相类似。由于在冻结和融化过程中，水分将向相变界面附近迁移，多年冻土上限附近地下冰的形成

Experimental Study on Heat Moisture Transfer in Lanzhou Loess during Freezing thawing Processes

The experimental results show that water content in the region below thawing front distinctly increase in quickly frozen uniform sample of Lanzhou loess during thawing when upper and bottom boundary conditions are controlled at sine function and constant temperature changing with time, respectively The same phenomenon is also observed under the same boundary condition when uniform Lanzhou loess sample is frozen, then thawed, after that refrozen Water continuously concentrates in the region nearby the maximum thawing depth of the sample in this way similar to the cumulation of water nearby permafrost table in nature condition during freezing and thawing Because water migrates in soil towards phase change front during freezing and thawing, the moisture cumulation just below permafrost table may be mainly attributed to thawing process of permafrost active layer during summer