Study on the evaluation method of heat transfer characteristics of rocks with cracks for the development of the deep ground.

为了分析地下热流的实验室实验，开发了一套个人计算机系统和一个采集温度图像的程序，然后用一个小型模型地面研究了孔隙水饱和的多孔介质中的热传递。在该实验装置中，可以建造不同渗透率的地面，并可以通过改变水头来确定任意数量的地下水流量。编制了有限元程序对实验结果进行了分析，并估算了各组分的热常数。对比理论和实验结果，研究了水流对土壤表观导热系数的影响，发现孔隙水对流换热对土壤整体导热系数有很强的影响，De Vries提出的经验公式给出了土壤导热系数的精确值。去年考察了渗流理论和等效包裹体方法在估算土壤热常数中的应用，结果表明，这些理论在估算土壤热常数时并不总是方便的，因为理论估算总是存在结构假设和平均过程的误差。此外，与这两个理论假设的估计值相比，本文提出的有限元计算方法给出了足够准确的结果。因此，利用渗流理论和等效夹杂方法进行的分析研究被排除在今年的研究之外。

A personal computer system and a program to capture thermographs was developed for the analyses of laboratory experiment of the heat flow in the ground and then the heat transfer in the porous media saturated by pore water was examined using a small model ground. In this experimental equipment the ground with different permeability can be constructed and any amount of ground water flow can be given by changing the water head. A FEM program was also developed to analyze the experimental results and to evaluate the thermal constants of the constituents. Comparing the theoretical results and experimental ones, effect of water flow to the apparent heat conductivity of soil was studied, and it was found that there are strong effect of convection of heat by pore water on the heat conductivity of soil as a whole and an empirical equation proposed by De Vries gives an accurate values of heat conductivity of the soils.Application of percolation theory and equivalent inclusion method to the estimation of thermal constants of soils were examined last year and it was already concluded that these theories are not always convenient to evaluate the thermal constants of soils because the theoretical estimation always contains errors caused by assumption of structures and averaging procedures. In addition to that it was found that the proposed method of FEM calculation gives enough accurate results compared to the values estimated from these two theoretical assumptions. Therefore analytical studies by use of percolation theory and equivalent inclusion method was excluded from the studies of this year.