| With the great development of highway transportation infrastructure in China,the construction of highway tunnel has also made remarkable achievements.The construction scale,construction speed and operation quantity are all the first in the world,and the construction difficulty is also in the forefront of the world.In the western region,due to the uplift of Qinghai-Tibet plateau and its expand to the northeast,formed the Hexi CorridorQilian Mountain-West Qinling Mountain-Longnan-Wenchuan arc high in-situ stress extrusion belt,cause in the belt Dangjinshan highway tunnel,Wushaoling railway tunnel and Muzhailing railway tunnel large extrusion deformation happened in construction.At the initial stage of construction,Muzhailing highway tunnel appeared serious extrusion deformation,and the arch replacement rate was once as high as 30%,which made the construction difficulty and safety risk increased sharply.Relying on Muzhailing highway tunnel,this paper selected the ridge section predicted by the design unit to have large deformation as the research object,and study the safety risks existing in the construction of ridge section by literature research method,checklist method,expert survey method,fuzzy hierarchy comprehensive evaluation method and consequence equivalent method.The main research contents and achievements are as follows:(1)Introduces the background of highway tunnel construction safety risk management and the significance of studying the safety risk management of large deformation highway tunnel construction,summarizes the research status of tunnel construction risk management at home and abroad,and analyzes the main problems existing in the research of risk management,identified research methods,research contents and technical route of this paper.(2)Summarized the theory of tunnel safety risk management,elaborated the basic concept of risk,tunnel safety risk identification theory,tunnel safety risk assessment theory and tunnel safety risk control theory,focused on the analysis of the common methods of risk identification and evaluation and their advantages and disadvantages.(3)According to hydrological and geological condition,design scheme and construction organization of the ridge section of Muzhailing highway tunnel,combined with the early-stage construction practice of the tunnel,select the checklist method based on engineering analogy in risk incidents and risk source recognition,identify the tunnel collapse,gushing water,large deformation,mashgas,environmental protection,inclined tunnel transportation,anti-slope drainage and long distance ventilation a total of eight risk events,and use expert survey method to estimate the above risk events.(4)Risk events of estimated grade iii or above are classified as major safety risk events,a detailed analysis,selecting evaluation index,establishing the evaluation index system,using the fuzzy hierarchy comprehensive evaluation method and consequences equivalent method to evaluate the probability and consequences of risk events occur,contrast risk grade standard,determine the highest risk level of the large deformation and tunnel collapse risk is grade iii,the highest risk level of gushing water and environmental protection risk is grade ii,and the overall risk grade of ridge section is grade iii.(5)According to the evaluation results and construction management mode,after improving the organizational structure,clarifying the work responsibilities and management process,specific control measures are put forward for various risks,which provides effective and credible management basis for Muzhailing highway tunnel construction and ensures more scientific and reasonable management decisions for tunnel construction.In order to achieve the purpose of ensuring safety,protecting the environment,ensuring the construction period,reasonable investment and improving efficiency.The above research not only explores the risk assessment methods,but also provides a reference for the safety risk management of large deformation tunnel construction. |
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