한국 중부 지역의 화강암 열물성

Abstract

Thermal and physical properties were measured on 206 Jurassic granite samples obtained from three boreholes in the central part of Korea. Thermal conductivity(λ), thermal diffusivity(α), and specific heat(Cp) were measured in a laboratory; the average values are λ=2.813 W/mK, α=1.296 mm 2 /sec, and Cp=0.816 J/gK, respectively. In addition, porosity(φ), and dry and saturated density(ρ) were measured in the laboratory; the average values are φ=0.01, ρ(dry)=2.662 g/cm 3 and ρ(saturated)=2.67 g/cm 3 , respectively. Thermal diffusivity of 10 granite samples were measured with increasing temperature from 25°C to 200°C. In this study, we found that thermal diffusivity at 200°C is about 30% lower than thermal diffusivity at 25°C. In correlation analysis, thermal conductivity increases with increasing thermal diffusivity. However, thermal conductivity does not show good correlation with porosity and density. Consequently, we know that thermal conductivity of granite would be more influenced by mineral composition than by porosity. We also derived ρ = �2.393 × φ + 2.705 from density and porosity data. XRD and XRF analysis were performed to investigate effects of mineral and chemical composition on thermal conductivity. From those results, we found that thermal conductivity increases with increasing quartz and SiO2, and decreases with increasing albite and Al2O3. Regression analysis using those mineral and chemical composition were carried out ; we found K = 0.0294VQuartz +1 .93 for quartz, K = 0.237WSiO2 � 14.09 for SiO2, and K = 0.053WSiO2 � 0.476WAl2O3 +6 .52 for SiO2 and Al2O3. Specific gravities were measured on 10 granite samples in the laboratory. The measured specific gravity depends on chemical compositions of granite. Therefore, specific gravity can be estimated by the felsic-mafic index(F) that is calculated from chemical composition. The estimated specific gravity ranges from 2.643 to 2.658. The average relative error between measured and estimated specific gravities is 0.677%.