冻融作用对土体干容重和含水量影响的试验研究*

  对青藏铁路沿线具有代表性的两种土：砂质粘土和轻亚粘土进行了室内冻融试验研究。试验在开放系统、不同初始干容重、含水量及温度条件下进行，水分由下向上补给。试验结果表明：经过多次冻融循环以后，土体的干容重趋于某一定值。这一定值与土体的初始干容重无关，而与土体的种类有关。本试验结果中砂质粘土稳定干容重为1.55 g•cm－3，轻亚粘土为1.78 g•cm－3。另外，发生冻融循环后的土体含水量比初始含水量大，而且经历冻融变化的部分增加的含水量要比保持融化状态部分增加的含水量要大。

TESTING STUDY ON INFLUENCE OF FREEZING AND THAWING ON DRY DENSITY AND WATER CONTENT OF SOIL

Sandy clay and sandy loam are the two typical kinds of soils along the Qinghai-Tibet railway. Under an open system environment，the two kinds of soils are tested in repeatedly freezing and thawing circulation experiments. In these experiments，all the soil samples are tested at the different dry density，water content and temperature. The results show that the final dry density is a constant after the repeatedly freezing and thawing. The final dry density of sandy clay is 1.55 g•cm－3，while that of sandy loam 1.78 g•cm－3. It can also be concluded that the final dry density of each soil sample depends on the soil type but not the original dry density. The repeatedly freezing and thawing circulation can change water content of soil. After the circulations，the water content of soil will increase，and the water content at the top part is greater than that at the bottom part due to water migration from bottom to top.