Abstract: Safety risk assessment should be carried out for extralong tunnels and tunnels under complex geological conditions. The safety risks of Yemaliang tunnel are analyzed and assessed by means of combination of qualitative analysis and quantitative analysis, based on expert investigating process and analytic hierarchy process. The study shows that: 1) The safety risk grade of Yemaliang tunnel is Grade Ⅲ. 2) There is no invincible risk. 3) It is proposed that dynamic risk assessment should be made and risk management should be strengthened so as to achieve the goal of safety, economic benefit, environment protection and high quality.

Key words: extralong tunnel, design phase, analytic hierarchy process, safety risk, factors weight