饱水砂土反复冻融时成冰条件的试验研究

Experimental Study on Conditions for Ice Formation of Saturated Sand in Freezing and Thawing Cycles

To study the conditions of ice formation during soil freezing and thawing, the controlled freezing and thawing test on the saturated sand was conducted in the laboratory. The results have shown that the temperatue at the end of the soil column changing periodically, which induces the freezing-thawing surface in the soil column moving up and down, is the necessary condition for ice formation. By the mechanism of vacuum and permeableness water is adsorbed to the place nearby the freezing-thawing surface and ice formed. Having water supply from the outside of the soil column is the ample condition for ice formation. It results the thickness of ice layer continuously increasing in freezing and thawing cycles. The location and the thickness of ice layer depend on the location of freezing-thawing surface and the times of freezing and thawing cycles. If the freezing-thawing surface keeps constant after each freezing and thawing cycle, then the thicker ice layer will be formed. In each freezing and thawing cycle, if the thaw depth is greater than the frost depth, then only one thin ice layer can be formed and contrarily, if the thaw depth is less than the frost depth, then multiple thin ice layers will be formed after many times of freezing and thawing cycles.