| Soil layer,as an important layer in the key zone of the earth,is an important channel for material and energy exchange in the key zone.It is of great significance to study the process of soil hydrothermal change for rational exploitation and utilization and protection of soil resources.Thermal conductivity,as the basic parameter to characterize soil thermal properties,is the key parameter of soil hydrothermal change law and its transmission model construction,which plays a key role in soil pollution prevention,engineering construction and shallow geothermal energy development and utilization.In view of this,this paper analyzes and studies the thermal probe testing device and algorithm,the influencing factors of thermal conductivity and the commonly used models of thermal conductivity,and draws the following conclusions:（1）The effect of the ratio of length to diameter of the thermal probe and the filler material on the thermal conductivity was investigated experimentally.The results show that the larger the ratio of length to diameter of thermal probe,the smaller the relative error of thermal conductivity measurement,the better the thermal probe with the ratio of length to diameter of 85.Comparing and analyzing the effect of filler material on thermal conductivity,it is concluded that epoxy resin is more stable and less error than copper powder.The method of pre-processing test data can improve the calculation accuracy of thermal conductivity.（2）The effect of moisture content and salt content on thermal conductivity of sand and clay is as follows:moisture content is not more than 20%,the thermal conductivity of clay and sand increases with the increase of moisture content,and the thermal conductivity of sand is greater than that of clay;for sand,when moisture content is fixed,Na2SO4 increases its thermal conductivity,the content of Na Cl increases its thermal conductivity,and the change of concentration of Na Cl has a greater effect on the thermal conductivity of soil.（3）The applicability of Campbell models,Johansen models,Cote and Konrad models and Lu-Ren models to sand and clay soils was analyzed.Johansen model is more suitable to calculate the thermal conductivity of soil with more clay.Cote and Konrad models and Lu-Ren are suitable for sand and clay.Campbell model is greatly influenced by soil texture parameters.In this paper,the soil texture parameters are modified and the parameters suitable for the calculation of thermal conductivity of sand and clay are given. |
