基于土壤孔隙结构的热导率和接触热导率标度规律的建立

土壤的热特性(热导率λ,比热c)和土壤水分含量θ是研究地表的能量平衡和水分平衡的关键参数。作为能准确测量土壤热特性和土壤水分含量的主要方法，单针和双针热脉冲探针方法已被广泛使用。但是目前仍有很多机理问题尚未解决。本研究拟通过室内和室外实验，理论建模和计算机模拟解决以下问题。(1). 在λ和接触热导率H有限大小的情况下，完善Jaeger1956年的热脉冲探针理论。在此理论基础上，分析单针和双针方法测量得到λ的差异以及误差来源，并用实验来验证。(2).通过利用同步光源X射线给出的土壤孔隙照片,重构三维土壤孔隙空间结构，结合有限元模拟。得到λ和H对孔隙空间结构参数的标度关系。(3). 加热探针半径以及土壤颗粒的粒径大小，对H的影响。(4). 在野外测量得到不同含水量条件下的土壤λ，H，c，θ。并和基于孔隙尺度的有限元模拟得到的λ和H对孔隙空间结构参数的标度关系对比，来检验相应的标度关系。

Soil thermal properties (heat conductivity λ, heat capacity c)and soil water content θ are key parematers for studying the energy balance and water balance near the surface. Single and dual probe heat pulse method are popularly used for measuring soil thermal properties and soil water content.However, there are some basic theoretical problems that were not solved, yet.In this study, we use indoor and outdoor experiments, theoretical model and computer simulation to solve the following problems.(1). For finite values of λ and contact heat conductivity H, we developed the theory of Jaeger 1956. Based on this theory, we carry out error analysis for single and dual probe method and compared with the experiments results. (2).Using synchrotron X-ray to take photos of soil pores and reconstructure three dimensional soil pores. The soil pores structure was then input into finite element method software for finding out the scaling relationships of λ and H. (3).The influence of the heaters diameters and soil particle size on measured H. (4).To measure λ，H，c，θoutdoor for soil with different water content. Then compared the experiments results with the λ，H values from pores scale finite element simulation, to verify the scaling relationships.