Research On The Prevention Of Frost Damage In Tunnels

Cold disasters like the fracture on the lining surface, peeling off, ice covering, watering and freezing of the road surface in tunnels have been greatly weakening the service capacity and producing heavy burden on the maintenance of many tunnels built in cold areas in our country. With the rapid development of our country's transportation and the implementation of the state's the policy of the Great Development of the Western Regions, a great many tunnels will be built in elevations areas or circumpolar areas in the Big West. Compared with traditional tunnels in the cold area, these tunnels will take large size and require higher technology. Moreover, the extreme climatic conditions are very unfavorable for these tunnels. Therefore, problems of how to take effective measures to prevent cold damages from happening during construction have constantly coming into our view and still remain to be solved. In order to these, the paper takes the construction of Tiziling Tunnel as an example and does a case study on the application of the tunnel anti-freezing and damage prevention technology in tunnels in cold areas, The main contents of the study include:(1) Based on our analysis of the causes of the cold damages in Tiziling Tunnel, our thorough survey of the literature both home and abroad and our examination of some typical tunnel anti-freezing projects, we proposed a technical scheme to add anti-freezing thermal-protective layers between the watertight layer and the two linings. The difficulty of this scheme lies in the design of such layer, including the choice of the material, the decision of the thickness of the layer and the construction method;(2) We tested the tunnel temperature field, and learned the rule of the temperature distribution. The test provided the basis for the design of the anti-freezing layer;.(3) By the principle of adiabatic, we calculated and decided the thickness of the layer by way of equivalent conversion;(4) Through the construction of the Tiziling Tunnel, we successfully solved the layer construction method problem, and thus the quality of the tunnel was ensured;(5) We conducted two field tests lasting for two winters on the result of our anti-freezing thermal-protection layer, which proved very effective.It is two years since the Tiziling Tunnel cold damage control project was put to service. We achieved our goal because since then no such damage as the liningsurface leaking and freezing has ever occurred. This shows that our scheme of adding anti-freezing thermal-protective layers to prevent cold damages is feasible. The first application of this method at home has discovered a new way to solving the cold damage problems in tunnels in cold areas, this has a great construction application prospect.