Large-scale ice avalanches pose serious risks owing to their high speed and long travel distances, and their mobility is increased by ice melting owing to frictional heat. Most motion models for large-scale ice avalanches have been constructed for specific scenarios, neglecting the key effect of frictional ice melting on their mobility and having limited applicability. In this study, a two-dimensional model combining thermodynamic and dynamic properties was proposed. This model, based on depth-averaged and granular flow theories, considers the friction weakening process to simulate the dynamics of ice avalanches. The governing equations for motion and heat transfer were solved by employing the finite volume and the Crank-Nicolson methods. The numerical simulation results showed that the friction weakening caused by the thermal effect on the sliding surface significantly reduced the friction coefficient between the ice mass and its substrate, increasing the travel distance of ice avalanches. The initial ice content in the shear band affects the friction coefficient during the viscous and Coulomb friction stages. The higher the initial ice content in the shear band, the lower the viscous resistance during the frictional heating-induced drag reduction stage, resulting in a longer sliding distance and larger coverage area. Notably, large-scale ice avalanches exhibit a "Volume Effect" similar to other mass movements such as landslides, debris flows, and rock avalanches. Ice avalanches with larger volumes exhibit greater mobility and coverage areas. The proposed model reveals the dynamic characteristics of large-scale ice avalanches under the effect of frictional heat and offers a valuable tool for dynamic analysis and supporting disaster risk reduction strategies.