Experimental study on thermal conductivity of remodel expansive rock and its influence factors

The effects of moisture content, dry density, temperature and volume deformation on the thermal conductivity of remodeled Nanning Tertiary expansive mudstone specimens were investigated by the thermal probe method. The research showed that the thermal conductivity of the remodeled expansive mudstone increased with the increase of moisture content and dry density, mainly because the increase of water content lowered the thermal resistance of the air in the mudstone and the increase in dry density brought the mudstone particles into closer contact with each other. The thermal conductivity increased by 135.7% when the water content increased from 10.4% to 21.9%, and thermal conductivity increased by 133.9% when the dry density increased from 1.50 g/cm(3) to 2.00 g/cm(3). Under the effect of latent heat transfer, the thermal conductivity of remodeled expansive mudstone increased with the growth of temperature and exhibited two different stages of slow growth and rapid growth. The particle size kept expanding and aggregating under the influence of temperature, which provided favorable conditions for latent heat transfer. The thermal conductivity of remodeled expansive mudstone decreased with the increase of the volume deformation rate. When the deformation rate increased from 0.5% to 5%, the thermal conductivity of expansive mudstone decreased by 5.7%-29.5%, due to the fact that the expansive mudstones are looser after water absorption and expansion.