Study On Risk Assessment System, Method And Application Of Lingjiang Bridge

The bridge engineering has long project life cycle, needs huge investment and complex technology, involves wide ranges, and once an accident happens, the impact is significant. From project establishment to long-term operational process, the bridge engineering possesses various factors that are difficult to predict, which will bring immeasurable loss to economic development if the failure of construction occurs. Building risk assessment system, studying the theory, method and management regulation of risk assessment of the bridge engineering and carrying out risk assessment in all stages of the project will help to improve the building management system of bridges, develop effective measures to deal with the risk of bridges and finally gain the greatest security with the minimum cost.The background of this paper focused on the building of Lingjiang Bridge of the eastern extension segment of TaiJin Highway. We analyzed the composition of the risk factors of the typical risk situation, used the qualitative method to identify the risks and listed the risks. To analyze risks after identifying, we used the qualitative and quantitative methods and the Fuzzy Comprehensive Evaluation to establish the Loss Model and the Probability Model of the risks. We put forward the grading standards of the probability and the loss of the risks and the risk assessment matrix. We obtained the estimate of the bridge risk events through calculating the probability and the loss of the risks.During the design stages, the bridge design programs are affected by the factors including the environment of a bridge location, cost and the complexity of construction technology, etc. The risk of each design is different. Therefore, after analyzing the design risk of Lingjiang Bridge, we chose the cable-stayed bridge with low towers from the three options including prestressed concrete continuous girder bridge, cable-stayed bridge with low towers and cable-stayed bridge with one tower for its reasonable structural design and risk. On this basis, we analyzed the invest risk and then proposed the control measures of design risk and investment risk. During the construction stage, the choice of the substructure construction plan is affected by the factors of navigation, geology, hydrology, climate and construction con-dition, etc. We proposed two construction programs of substructure-double-wall steel cofferdam and construction site. We identified and analyzed their construction risk and then chose the construction site construction program for its less risk, structural stability, withstand strong typhoons and tidal resistance though the fee is higher.During the operational stage, considering busy navigation of Lingjiang, we analyzed several ship collision models that commonly used at present and then proposed the AASHTO Model to evaluate the ship collision risk of Lingjiang Bridge. The results showed that though the ship collision risk was low, it still should take measures to reduce the risk of ship collision.Finally, we draw up the management regulation of building risks of bridge engineering on the basis of generalizing the objective, content, strategy and process of the management regulation of building risks of bridge engineering.