A multi-factor comprehensive risk assessment method of karst tunnels and its engineering application

Abstract

The tunnel collapse, a large deformation of surrounding rock, water and mud inrush are the main geological disasters in the process of tunnel construction. In order to control the above construction risks, the multi-factor comprehensive risk assessment method of karst tunnels is investigated in this study. Firstly, twelve influencing factors are selected as comprehensive risk assessment indexes of the karst tunnel from the aspects of karst hydrogeology and engineering geology conditions, as well as construction factors. The corresponding grading standards of assessment indexes are determined. The tunnel collapse, large deformation of surrounding rock, water and mud inrush, and comprehensive risk assessment index systems are established respectively. Secondly, the unascertained measure analysis for assessment indexes is carried out. The single risk grade and comprehensive risk grade are judged respectively by using credible degree recognition criteria. Thirdly, the most serious geological disaster is ascertained based on the riskiest principle, and then comprehensive risk control theories and technical systems of the karst tunnel can be built. Finally, the established unascertained measure model and the proposed multi-factor comprehensive risk assessment method are applied to the risk assessment of the Yichang-Wanzhou Railway Dazhiping tunnel. The assessment results are in good agreement with the site construction conditions. The research results provide an effective approach for comprehensive risk assessment methods of karst tunnels.