Study On The Collapse Risk Assessment Of Tunnel Construction Project

Chinese tunnel construction, though started late, but has been rapidly developing recently and has made remarkable achievements especially since the recent high-speed rail era. Our country currently owns the most tunnels and underground engineering, the most complex engineering and fastest-growing development around the world. In particular, the success of a series of long, big section tunnels projects indicates that China has made considerable progress. Tunnel project commonly has large investment, long construction period, complex construction technology, unpredictable risk factors and environment impact, etc. In recent years, engineering disaster which has happened frequently may expose some contradictions and problems. The collapse accident due to complex geological conditions, construction conditions, disturbance blasting and other factors in tunnel construction process, has become a big problem in tunnel construction.Through the more detailed project information of the tunnel construction in processing, statistics and analysis the factors of causing landslides, to identify the fundamental cause risk factors, and the use of Fault Tree Theory, building a accident tree structure of tunnel landslide risk assessment. Whereby the fault tree of tunnel construction collapse accident causes is the established according to the results of statistical analysis and the end event is determined. Then draw the fault tree, and make qualitative analysis to explore the various risk factors impact on the construction safety. On the basis of statistical analysis, combine road and rail tunnel risk assessment and establish tunnel construction collapse risk assessment process, construct evaluation index system and evaluation criteria, quantify qualitative indicators, normalize each index and finally complete tunnel collapse assessment forms. Select several typical tunnel constructions as assessment system, apply risk assessment forms’ functions and verify the reasonableness and practicability of this evaluation system. According to the site and the feedback results, adjust tunnel collapse evaluation index. Based on the assessment results, the risk of collapse of tunnel construction have made the appropriate source of risk control measures, to develop appropriate management plans and measures so that the construction phase of the security risks controllable.Based on the risk assessment of landslide in construction phase, a serials of cycle assessment forms have been used to assess tunnel risk which could make tunnel collapse in a predictable state and reduce and minimize the loss to minimize of collapse. Another research method used in the paper is the theory of fault tree risk assessment which revises and improves landslide risk assessment forms along with field situations. The research outcomes have been applied to Majiapo tunnel, Guchengling tunnel and Taiyangshan tunnel confirming the science and rationality of this study and providing a high reference value for other tunnel collapse risk assessment projects.