Abstract: In TBM construction of a deep buried headrace tunnel, it is very difficult to lower the temperature and control the dust due to thermal storage effect and heat transfer in surrounding rock. Previous studies have not considered the influence of thermal conduction in the rock, and lack an analysis method for calculating its effective thermal conductivity. To address these two issues, first we develop a new analytical method for effective thermal conductivity calculations based on fractal analysis using a polygonal discrete fracture network model. Then, we construct an Euler-Lagrange two-phase flow model for the TBM construction of deep buried headrace tunnels, considering the effects of heat conduction in the surrounding rock and its heat exchange with the wind flow over its surface. Results of a case study show that the effective thermal conductivity of surrounding rock is 0.47 W/m?K, which is far less than that of normal rock. The accuracy and reliability of our model is verified by comparing the simulation results with our field experiment data and other models. This study would lay a theoretical and technical basis for similar TBM construction ventilation of deep buried headrace tunnels.

Key words: deep buried headrace tunnel, TBM construction, Euler-Lagrange two-phase flow model, heat transfer in surrounding rock, effective thermal conductivity