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选取冻胀敏感性粉质黏土,利用人工冻土一维冻胀试验系统进行不同变温幅度和间歇时间作用下的后间歇冻结试验,以试样冻深达到稳定阶段为初始时刻分析冻结锋面、冻胀量及温度梯度变化曲线,得到冷端变温幅度和间歇时间对土体冻胀的影响规律。结果表明:不同变温幅度作用下的冻结锋面、冻胀量曲线呈周期性变化,变化周期为240 min,与间歇时间相同。随着变温幅度的增大,冻胀量分别为3.38,2.55 mm,与连续冻结模式相比,冻胀量分别减少了23.2%,42.0%。相同变温幅度,间歇时间为2,4,8 h的土体冻胀量曲线分别呈抛物型、阶梯型和折线型增长趋势,冻胀量分别为2.82,2.55和1.81 mm。土体冻胀量随着间歇时间的增大而减小,但间歇时间不宜大于8 h,否则分凝冰层融化,冻胀量衰减,对于实际冻结工程,则会影响冻土壁强度。
Frozen swelled susceptible silty clay was selected, and the frozen intermittent freeze-thaw test was carried out by using one-dimensional frost heave test system of artificial frozen soils. The freeze-frost heave reached the stable stage as the initial time to analyze the frozen front and frozen The amount of expansion and the temperature gradient curve, the influence law of the frost heaving of the soil is obtained by changing the temperature range and the intermittent time of the cold side. The results show that the freezing fronts and frost heaving volume curves change periodically with different temperature ranges, with a variation period of 240 min, which is the same as the intermittent time. The frost heaving volume was 3.38 and 2.55 mm, respectively, with the increase of temperature range. Compared with the continuous freezing mode, the frost heaving volume decreased by 23.2% and 42.0% respectively. The frost heave curves of soil with the same temperature range and intermittent time of 2, 4 and 8 h showed parabolic, stepped and polygonal trend, respectively. The frost heaving volume was 2.82, 2.55 and 1.81 mm respectively. The amount of soil frost heave decreases with the increase of intermittent time, but the intermittent time should not be more than 8 h. Otherwise, the segregation ice layer melts and the frost heave volume decays. For the actual freezing project, the strength of the frozen soil wall will be affected.