Three-dimensional nonlinear analysis for coupled problem of heat transfer of surrounding rock and heat convection between air in Fenghuo Mountain tunnel and surrounding rock

According to the essential theories of heat transfer,geocryology and hydraulics,taking the coupled problem of the heat transfer of the rock surrounding the tunnel and the heat convection between the air in the tunnel and the rock surrounding the tunnel into account,three-dimensional calculating model of the coupled problem were presented,the finite element formulae of this problem were obtained by Galerkin’s method,and the computer program of the finite element was compiled.Using the program,three-dimensional nonlinear analysis for the coupled problem of the heat transfer of the rock surrounding the tunnel and the heat convection between the air in the tunnel and the rock surrounding Fenghuo mountain tunnel on Qinghai-Tibet Railway was made.The results show that the thawing-freezing situation of the rock surrounding the tunnel can correctly be forecasted without the knowedge of the inside air temperature of the tunnel.Therefore,the great cost of field observation for the air temperature in the tunnel can be saved.