Abstract:

Avalanche is one of main natural geological disasters for the engineering construction in plateau alpine area, and is also one of the important factors affecting construction and operation safety of railway tunnel project. In order to make a reasonable scheme of avalanche prevention and control, the potential avalanche areas above tunnel portals are determined by field investigation and analysis of the natural geographical conditions in tunnel site. The avalanche diffusion distance and the impact force of avalanche on the portal are calculated and analyzed by using tan α parameter mapping method. Based on calculation results, avalanche prevention schemes, i.e. 25 m open cut tunnel at the entrance of main tunnel and snow guide wall at the top of the portal, 5 m open cut tunnel at the exit and 15 m open cut tunnel at the entrance of the safe tunnel, are put forward. The schemes effectively prevent the danger of the avalanche disaster to the railway tunnel and ensure the safety of railway tunnel operation in winter.

Key words: alpine area, railway tunnel, avalanche, diffusion distance, tan α parametric mapping method, prevention and control scheme