A Research On Frost Heaveforce And Temperature Field Inside Long Road Tunnels In Cold Area

Along with the rapid development of Chinese Economy and deepening of Western Development Strategy, more and more tunnels are or will be contracted in cold areas, such as high-altitude regions and high-latitude regions, where these tunnels are exposed to severe freezing damage problems. Thereforce, the freezing damage problems have to be concerned during the whole process, from design, to construction, to operation. With the highest road tunnel in the world, the Que’er Mountain, as engineering background, this thesis firstly took classifcal frezzing damages and their causes into analysis.After finding out the casues of freezing damages, FEM was adopted to analyze the frost heaveforce happening in cavities and cracks of surrounding rock masses. Based on governing equations of air field and temperature field, the FVM then was adopted to simulate the temperature field varies versus time and space under different outside temperatures, different ventilation methods and different tunnels lengths in order to find the range of long tunnels vulnerable to freezing damage. The contents and results of this research are listed beloew:(1) Carried out a stastic research on the phenomena of freezing damages in cold-area tunnels. Practical engineering background was combined to study the causes of those freezing damages.(2) FEM was adopted to study the frost heaveforce caused by ice-water phase changing in cavities and cracks behind the tunnel’s linings. For cavities, the changing laws of additional stress, damages and deformation to the tunnel structures were studied after taking into accounts of different factors, like frost heaving ratio, height and length of cavities, and different location of cavities. For crushing surrounding rock mass, the magnitude of frost heaveforce was estimated and additional loads to tunnel structures were evluated after taking into account of different angle and spacing of cracks in those crushing surrounding rock masses. The vulnerable locations inside of tunnel sturctures were identified.(3) Based on the governing equations of air field and temperature field, FVM was adopted to study how the temperature field inside of the tunnels varied spatially and temporally with changing of outside tempearture, different vantilation methods and different tunnels’ lengths. The covering range of nagative temperature, the amplitude of temperature variation inside of tunnels, the distribution laws of temperatures inside of tunnels under different ventalation methods were clarified.