Study On Safety Risk Assessment Of The In-service Urban Bridge Clusters In The Three Gorges Reservoir Area

The Three Gorges Reservoir area is characterized by complex topography,large periodic variation of Yangtze River water level and frequent geological disasters caused by deep-water erosion,which seriously affect the operation safety of Bridges in service.In addition,with the rapid development of the construction of towns and transportation facilities in the reservoir area,the traffic volume has been greatly increased,the urban traffic density and congestion have been increasingly aggravated,and the over-limit and overloaded vehicles have occurred from time to time,which brings great pressure to the management of urban Bridges.Therefore,it is of great significance to carry out safety risk assessment of urban Bridges during operation.At present,the risk assessment of bridge mainly focuses on the construction stage,and rarely carries out the risk assessment of bridge during operation.In this thesis,the potential risks of the urban bridge cluster in the Three Gorges Reservoir area in the operation stage are assessed,and targeted control measures are proposed to improve the level of urban bridge management and ensure the safety of bridge operation.The main research contents and conclusions of this thesis are as follows:(1)Based on the investigation and research on the operation safety risk of urban bridge cluster in the Three Gorges Reservoir area,this paper summarizes and analyzes the prominent problems facing the operation safety of urban bridge cluster in the Three Gorges Reservoir area represented by Wanzhou District.It is pointed out that the key factors affecting the operation safety of service Bridges are complex terrain,bad traffic environment,periodic change of reservoir water level,frequent geological disasters such as landslides,significant influence of adjacent structures,and collision of vehicles and ships.(2)Based on the characteristics of urban bridge clusters in the Three Gorges Reservoir area and focusing on the safety problems that may be faced in the operation period,this paper identifies the risk sources of the security risks of urban bridge clusters in the operation period of the Three Gorges Reservoir area,establishes the operation security risk identification technology of urban bridge clusters,and defines the operation security risk assessment objects of urban bridge clusters.The regional and systematic risk sources of urban bridge clusters in the Three Gorges reservoir area are obtained.(3)An operational security risk assessment technology for urban bridge clusters is established,and the weight coefficient of impact factors is calculated by comprehensive use of expert scoring method and analytic hierarchy process(AHP)method.An associated risk assessment method for bridge clusters is proposed based on the multi-domain source progressive model.According to the characteristics of assessment objects,RIF risk assessment method and risk matrix method are adopted to carry out risk assessment.(4)Based on the safety risk assessment results of urban bridge clusters in the operation period of the Three Gorges Reservoir area,targeted management and control measures and coping mechanisms are proposed,so as to improve the ability of urban bridge managers to prevent and control security risks of urban bridge clusters.(5)Based on the project of 114 bridge clusters in Wanzhou City,the central city of the Three Gorges Reservoir area,the associated risk assessment model of bridge clusters in operation period is constructed,and the operational security risks of bridge clusters are identified through the multi-domain source progressive system.The results of bridge cluster risk assessment are consistent with the results of bridge regular testing for many years,which proves the feasibility and practicability of the risk assessment model,and provides technical support for guaranteeing the operation safety of bridge cluster in Wanzhou urban area.