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冻融循环作用改变了土体结构及热物理性质,进而影响了土体温度变化过程,土体冻结锋面的稳定位置也随之变化.为研究冻融循环作用下土体冻结锋面的移动规律,进行了开放系统下的兰州黄土冻融循环试验.试验结果表明:冻结初期冻结锋面迅速下移,冷端温度稳定后其下移速度降低,当土体温度达到平衡时,冻结锋面位置趋于稳定;冻结锋面稳定深度随冻融循环次数的增加而增加.为阐述黄土冻结锋面随着时间变化规律,采用时间比拟法得到了冻融循环次数与冻融时间相似比拟曲线.由拟合曲线得第6次冻融循环后土体冻结锋面稳定在土样高度24.4 mm处,实测稳定在24.3 mm处,相对误差为0.4%.
The freeze-thaw cycle changes the structure and thermophysical properties of the soil, which in turn affects the process of soil temperature change, and the stable position of the frozen front also changes.To study the movement of the frozen front under the action of the freeze-thaw cycle, The freeze-thaw cycle of Lanzhou loess under open system was carried out.The experimental results show that the frost front moves down rapidly at the initial stage of freezing, and the downward moving speed decreases when the temperature of the cold end stabilizes, and the frost front position tends to be stable when the soil temperature reaches equilibrium ; The freezing front stability depth increases with the increase of the number of freeze-thaw cycles.In order to elaborate the law of the frozen front of loess with time, a similar curve of freeze-thaw cycles and freeze-thaw time is obtained by time comparison method, After 6 freeze-thaw cycles, the frozen front of the soil stabilized at a soil height of 24.4 mm and the measured stability was at 24.3 mm, with a relative error of 0.4%.