Alpine Tunnel Structure Of Mechanical Property

With the rapid development of the national economy, especially with the development of the strategy of China Western Development, more and more tunnels will be constructed in the cold region of the high altitude or the high latitude in our country. Because these regions suffer from particular climate, the tunnels are often subject to frost damages - especially when the groundwater becomes abundant -which directly threatens the structure of the tunnels and their operation safety, and thereby results in serious economic losses. Therefore, how to take effective measures in the construction of tunnels in cold regions to avoid or reduce the frost damages is a problem for tunnel workers, which calls for immediate solution. This dissertation takes Qing-Shashan Tunnel as the background, the longest tunnel in the cold region which is under construction at present in Qinghai Province to develop the tunnel structure stress research of the cold region. This tunnel is located at the freeway from Ping'an to A'dai. The project installs various kinds of organs to test the stress or strain for the tunnel, collects and analyzes the on-spot data for more than two years, carries on numerical simulation by large-size finite unit program ANSYS, and concludes that the present design parameters of the Qing-Shashan Tunnel is feasible, and that it can satisfy the safety requirement for the structure for later operation of the Tunnel. As for the section subject to seasonal freezing at the entrance of the tunnel, the study carries on the analysis method for the coupled problems of stress field and temperature field by the numerical simulation computing the change of the frost force of 50 years and comes to the conclusion that the frost force is about 1.90MPa in the month when the temperature of the surrounding rocks is coldest. The frost force doesn't do a great damage to the structure.