Risk assessment and control measures of collapse for tunnel construction

In order to prevent tunnel collapse and optimize tunnel design before tunnel construction, the collapse risk of Wolonggang Tunnel was taken as research object, the safety of tunnel primary shoring was analyzed, the risk factors of tunnel collapse were cleared, risk sources were identified combined with tunnel geology conditions, and analytic hierarchy process was used to rank the importantces of risk resources.The probability grades and risk loss grades were confirmed through expert investigation, and the grades of collapse risk were given by using risk matrix technique.Analysis result indicates that tunnel collapse inducements include the prompt closing of primary shoring, the removing occasion of temporary timbering, the close following of secondary lining and blasting concussion.The collapse risk grade of Wolonggang Tunnel is grade Ⅲ and is higher.