Analytical and numerical modeling for the effects of thermal insulation in underground tunnels

The heat flow generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels. Insulation layers with lower thermal conductivities on tunnel walls and roof ceilings are believed to supply a thermo-barrier for heat abatement. However, it is found that no systematic theoretical investigations were made to predict and confirm the effectiveness of underground thermal insulation. Specifically, investigations on the underground insulation problems involving heat flows through the semi-infinite hot rock mass and insulation layer were not sufficient. Thus, in this paper, the thermal characteristics, accompanied with heat flow through the semi-infinite rock mass and the insulation layer, were modeled by both analytical and numerical methods with focus on underground mine tunnels. The close agreements between models have indicated that the thermal insulation applied on tunnel surfaces is able to provide promising heat abatement effects.