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开展了饱和青藏粉土在开放系统不同温度梯度条件下的单向冻结试验,对冻结过程中冻结深度和冻胀速率的发展变化过程进行了研究.结果表明:不同顶板温度下,土样均在25 h左右达到冻结稳定状态,之后冻结深度基本不再发生变化.土样冻结过程中,冻胀速率表现为快速减小、较小值保持稳定、快速增大、较大值保持稳定四个阶段.基于以上试验结果,对土样冻结过程中冻胀率的变化过程进行了研究,发现冻胀率随冻结深度的增加先减小后增加,冻胀率从减小变为增大的时刻就是冻结深度趋于稳定的时刻,而冻胀率快速增大的时刻为冻胀速率进入较大值保持阶段的时刻.冻胀率变化的内在机理为土样冻结过程中由冰透镜体分凝所导致的未冻区固结和已冻区冻胀共同作用的结果.
The unidirectional freezing experiment of saturated Qinghai-Ssangyong silt under different temperature gradient of open system was carried out, and the development process of freezing depth and frost heave rate in freezing process was studied.The results showed that under different roof temperatures, 25 h or so, the frozen depth basically remained unchanged. During the freezing process of soil samples, the frost heaving rate showed a rapid decrease, the smaller value remained stable, rapidly increased, and the larger value remained stable in four stages Based on the above test results, the change process of frost heave rate during the freezing process of soil samples was studied and it was found that the frost heaving rate first decreased and then increased with the increase of freezing depth, and the time when frost heaving rate changed from reduced to increased The time when the freezing depth tends to be stable and the time when the frost heave rate rapidly increases is the moment when the frost heave rate enters the larger value holding stage.The internal mechanism of the frost heave rate change is that the frost- Resulting in the frozen zone consolidation has been frozen zone and frost heaving joint results.