冻土模型试验试样冻结时间计算分析

快速简单地确定试样的冻结时间，对模型试验的设计具有重要意义。首先进行了不同干密度冻土模型试样整体冻结达到预设负温的试验，发现试样整体降到预设负温的时间随着干密度的增大而略有增加。然后利用COMSOL Multiphysics软件，在不考虑水分迁移的条件下，对不同干密度粉砂土试样和不同尺度条件下的正方体亚黏土试样的冻结时间进行数值模拟。将模拟结果与试验结果进行对比，发现简化条件下不同干密度的粉砂土试样能反应试样在冻结过程中冻结时间的主要特征，模拟结果中达到预设负温的时间与试验的实测结果基本吻合。正方体试样数值模拟的结果表明在同一干密度、同一含水量条件下，试样降到预设负温的时间随着体积的增大呈现幂函数增大的规律。所以，在进行模型试验设计时，可先根据试验条件进行简单的数值分析，以较合理、经济的安排试验时间，同时也可保证试样冻结质量。

Calculation and analysis of freezing time of frozen soil model test specimen

Quick and easy determination of the freezing time of a specimen is of great significance for the design of model test. Firstly, the freezing test of frozen soil specimens with different dry densities was carried out. It was found that the freezing time increases slightly with the increase of dry density. Then the freezing time of silty sand specimens with different dry densities and sub-clay cube specimens with different scales was simulated by COMSOL Multiphysics software without considering water migration. Comparing with the test results, it was found that the numerical simulation results of silty sand specimens with different dry densities under the simplified conditions can reflect the main characteristics of temperature change during freezing process, and the calculated time for the specimen to reach the preset negative temperature is basically consistent with the measured results. The results of numerical simulation of cubic specimen also show that the time when the specimen drops to the preset negative temperature increases with increase of volume under the same dry density and water content, and follow a power function. Therefore, in the process of model test design, a simple numerical analysis can be carried out according to the test conditions, in order to arrange the test time reasonably and economically, while ensuring the freezing quality of the specimen.