In tropical areas where coral calcareous sands are prevalent, artificial freezing techniques are frequently employed during construction. However, the fundamental thermodynamic behaviors and moisture dynamics of calcareous sands under freezing conditions are poorly understood. Therefore, we conducted laboratory tests and developed a numerical model to capture the total moisture, liquid water, and ice contents of calcareous sand during artificial freezing. The thermal fiber Bragg grating (T − FBG) and frequency − domain reflectometry methods were used in the study. Freezing characteristic curves were quantitatively analyzed with taking into account the initial moisture content and ambient temperature. The results indicate that T − FBG effectively estimates the total moisture content in unfrozen and frozen calcareous sand, as well as ice content in frozen soil, with less than 0.029 m3/m3 error. Ice melting induced by T − FBG heating is affected by the initial moisture content, heating duration, power, and ambient temperature. However, the maximum change is below 0.008 m3/m3, which is negligible. The van Genuchten model accurately describes the liquid moisture–temperature relationship of unsaturated calcareous sand, with an R2 exceeding 0.98. The residual–initial moisture content relationship follows a quadratic function. During freezing, the temperature reduction aligns with the Kozlowski model, and the liquid moisture–temperature relationship follows a cubic polynomial function.

中文翻译：

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人工冻结过程中珊瑚钙质砂中冻结和未冻结的水分含量估计


在珊瑚钙质砂盛行的热带地区，施工过程中经常采用人工冻结技术。然而，人们对钙质砂在冰冻条件下的基本热力学行为和水分动力学知之甚少。因此，我们进行了实验室测试并开发了一个数值模型来捕获人工冻结过程中钙质砂的总水分、液态水和冰含量。该研究使用了热光纤布拉格光栅 （T − FBG） 和频域反射法。定量分析冻结特性曲线，同时考虑初始水分含量和环境温度。结果表明，T − FBG 可以有效地估计未冻土和冻土中的总含水量，以及冻土中的冰含量，误差小于 0.029 m3/m3。T − FBG 加热引起的冰融化受初始水分含量、加热持续时间、功率和环境温度的影响。但是，最大变化低于 0.008 m3/m3，可以忽略不计。van Genuchten 模型准确地描述了不饱和钙质砂的液体水分-温度关系，R2 超过 0.98。残余水分-初始水分含量关系服从二次函数。在冻结过程中，温度降低与 Kozlowski 模型一致，液体水分-温度关系服从三次多项式函数。