人工冻土多圈管冻融全过程温度场模型试验研究

Model test study of temperature field in freezing and thawing process of artificial frozen soil based on multi-coil freezing pipes

为掌握多圈管冻结壁温度场形成及融化规律,进行了人工冻土多圈管冻融全过程模型试验研究。试验结果表明:冻结与融化过程中的土体温度快速变化速率相当;融化阶段,土体温度在相变点处需要保持一个相对稳定的长时间过程;融化过程中冻结壁温度沿径向方向整体呈规则的二次抛物曲线分布,冻结壁平均温度随时间变化的关系可以用幂函数来表示;在冻结91.7 h的前提下,得到冻结壁融冻时间比介于1.47～2.04之间。试验结果为井筒冻结设计、壁间注浆最佳时间选取提供了理论依据。

We conducted model test study on the whole freezing and thawing process of artificial frozen soil based on multi - coil freezing pipes to master the formation and melting law of freezing wall temperature field of multi - coil pipes. The test results indicated that the change rate of soil temperature in freezing process approximately equaled to that of thawing process. The soil temperature is observed to maintain stable in a relatively long duration at the point of phase - transition when the soil melts. In the melting process, the temperature of freezing wall was in accord with quadratic parabola along the radial direction and the aver- age temperature change of frozen wall with time was in a power function curve. The time ratio of freezing - thawing is kept in a range of 1.47 - 2.04 in a freezing time of 91.7 h. The test results provided basis for the freezing design of shaft and the time se- lection of wall clearance grouting.