Numerical modeling of thawing in frozen rocks of underground mines caused by backfilling

The thawing effect due to backfilling in permafrost mining rocks is investigated. The heat transfer equation in rock and backfill is obtained by considering the effect of phase change, heat generation due to cement hydration and temperature dependent material properties. The governing equations are solved using a finite volume numerical method and the phase change phenomenon is modeled based on the manipulation of specific heat, thermal conductivity and density of rock and backfill. The harmonic mean method was employed to handle the change of thermal properties. The effects of different influential parameters such as cement content of backfill, water content of rock and backfill, thermal conductivity of rock and filling material, and the number of adjacent stopes are investigated. Eventually, using the resulting temperature and phase field, a new parameter regarded as the radius of thawing, is introduced.

► Heat transfer analysis of backfilling in permafrost mines is carried out.
► Cement content of backfill and thermal conductivity of rock play important roles in heat transfer.
► Effect of neighboring stopes on each other is little.
► Higher values of water content of backfill result in lower thawing depths.