Estimating Hydraulic and Thermal Conductivities of Crushed Granite Using Porosity and Equivalent Particle Size

This paper presents an experimental study of the effect of porosity and particle size on the hydraulic conductivity and thermal conductivity of sand-sized crushed granite particles with diameters ranging from 0.08–10 mm. The results show that the hydraulic conductivity varies with particle size and porosity, but thermal conductivity varies primarily with porosity. Estimating methods found in the literature are used in an attempt to predict the measured hydraulic and thermal conductivities of the crushed granite materials. The results show that the hydraulic conductivity model of Chapuis generally yields accurate estimated values for $d_{10}^2{n}^3/(1-n{)}^2$ larger than $0.01{\mathrm{mm}}^2$. Below this critical point, the estimating method progressively yields larger values of hydraulic conductivity. A new set of empirical parameters are proposed to extend the use of this method to crushed granite materials at low $d_{10}^2{n}^3/(1-n{)}^2$ values. It is also shown that predicted thermal conductivity values obtained with the Côté and Konrad model agree well with the experimental data. Issues regarding the extension of the models to coarser materials are discussed.