Abstract: The problems of high temperature on working surface always appear in deepburied long tunnels. Based on radial and axial twodimensional axisymmetric surrounding rock temperature heat conduction model of the tunnel, the third type of boundary conditions is introduced to derive the theoretical solution of surrounding rock temperature. Taking the mountainous section of Gaoligongshan railway tunnel as an example, the temperature distribution of surrounding rock is predicted and analyzed when the temperature inside the actual tunnel meets the requirement of specification. The results show that the radial maximum temperature gradient of tunnel section appears on the inner wall and the boundary between the surrounding rock and the lining. The radial surrounding rock temperature varies with the axial position of the entire tunnel, but it changes obviously only within about 20 meters at both ends of the entrance and exit. Increasing the convective heat transfer coefficient of the inner wall surface of the tunnel will increase the average temperature gradient in the lining, which will lead to an increase of cooling load.

Key words: high ground temperature, tunnel, surrounding rock temperature, theoretical solution