不同间歇冻结模式土体冻胀控制试验研究

Experiments on controlling frost heave of artificial frozen soil with different intermittent freezing mode

选取冻胀敏感性粉质粘土,进行了连续冻结、全间歇冻结、后间歇冻结模式下的冻胀试验,得出了土体冻胀量、冻结锋面、温度梯度的变化规律及冻结模式与冻胀控制之间的关系.结果表明:与连续冻结模式相比,全间歇冻结、后间歇冻结模式下的冻胀量分别减少了14.4%、43.6%.不同变温起始时间对冻土冻胀控制效果不同,后间歇冻结模式能够更加有效地控制冻胀量的发展.后间歇冻结模式下,土体内已冻区的温度梯度小,是造成后间歇冻结模式下土体冻胀量小于全间歇冻结模式下土体冻胀量的主要原因,可以考虑通过减小冻胀量快速增长阶段曲线的斜率更有效地进行冻胀控制.

In this paper, frost heave experiments using frost susceptible silty clay were carried out under continuous freezing mode, intermittent freezing mode and continuous-intermittent freezing mode. The variation of frost heave, freezing front, temperature gradient and the relationships between frost heave controlling and freezing mode are acquired. The results showed that the frost heave amount in intermittent freezing mode and continuous-intermittent freezing mode is reduced by 14.4% and 43.6% respectively more than that of continuous freezing mode. The effects on controlling frost heave were influenced obviously by different beginning time of changing temperature. The development of frost heave can he effectively restrained by continuous-intermittent freezing mode. In continuous-intermittent freezing mode, due to the smaller temperature gradient in frozen zone of soil sample, frost heave magnitudes in continuous-intermittent freezing mode are less than that in intermittent freezing mode. And therefore the amount of frost heave efficiently can be reduced by decreasing the slope of frost heave curves at rapidly increasing stages.