非饱和（冻）土导热系数预估模型研究

岩土材料的导热系数是岩土工程温度场分析及建筑热工计算中的重要参数。研究旨在建立一个基于归一化导热系数概念和以土的干燥和饱和状态导热系数为基准的非饱和土导热系数的通用预估模型。通过对文献中328组实测数据的分析发现，将同类土在不同密实度条件下的各种导热系数-含水率曲线簇进行归一化处理后，可以得到惟一的归一化导热系数kr与饱和度Sr（归一化含水率）关系，1/kr与1/Sr呈相关性较好的线性关系，而每支1/kr-1/Sr直线均通过坐标（1，1）点的斜率由土质类型决定。据此提出了一个集成土质类型、密实度（孔隙率）和含水率（饱和度）等因素综合影响的融土和冻土导热系数通用预估模型，并给出了导热系数预估模型中土质参数的取值范围，以及融土和冻土处于完全干燥状态和饱和状态的确定方法。对预估模型进行验证结果表明，所提出的非饱和土导热系数预估模型具有较好准确性。

Study of thermal conductivity model for unsaturated unfrozen and frozen soils

The thermal conductivity of soils is a key parameter in analysis of soil heat transfer in geotechnical engineering. This paper intends to develop a generalized thermal conductivity model for unsaturated unfrozen and frozen soils based on the concept of normalized thermal conductivity with respect to dry and saturated states of soils. 328 groups of experimental results for unfrozen and frozen soils, such as gravels, sands, silts, clays and peat, available from the literature were analyzed to develop the general relationship between the normalized thermal conductivity of soils and the degree of saturation. A unique normalized thermal conductivity and degree of saturation (normalized water content) relationship is obtained for the soils with different porosity and different thermal conductivity and water content relationships. There is a strong linear relationship between the inverse of normalized thermal conductivity (1/kr) and the inverse of degree of saturation (1/Sr) with lines passing through the coordinate (1,1). The soil types control the slope of the 1/kr-1/Sr lines. Accordingly, the model integrating the effects of soil types, density (or porosity) and water content (or degree of saturation) on the thermal conductivity of unfrozen and frozen soils is proposed. Method and parameters for calculating the thermal conductivity of dry and unfrozen or frozen saturated soils are given. The model generally predicts the thermal conductivity within an error of 20% for all kinds of (unfrozen and frozen) soils studied.