A static risk assessment model for underwater shield tunnel construction
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Indian Academy of Sciences Sadhana(0123456789().,-volV)F T3](0123456789().,-volV)
A static risk assessment model for underwater shield tunnel construction ZHIQIANG WU1,* and SHULIANG ZOU2 1
School of Civil Engineering, Housing and Urban-Rural Development of Heng Yang, University of South China, Hengyang, China 2 School of Civil Engineering, University of South China, Hengyang, China e-mail: [email protected]; [email protected] MS received 9 November 2019; revised 10 February 2020; accepted 16 February 2020 Abstract. The shield method is widely used in underwater tunnel construction. However, the shield construction process faces many uncertain risk factors that increase the level of safety risk during shield tunnel construction. Therefore, risk assessment has become a necessary task in the early stages of tunnel construction. In this study, a new risk assessment model for underwater shield tunnel construction is proposed that combines a normal cloud model with an entropy weight method. The model contains 20 assessment indexes and gives the range of each index corresponding to different risk levels, which comprehensively reflects the influencing factors of risk. By using a normal cloud model, the fuzziness and randomness of risk assessment data are taken into account effectively, and the reliability of assessment results is increased. Based on an entropy weight method, the rules and characteristics of the evaluation data in the model are considered, and the weight coefficient of the evaluation index is determined to avoid the subjectivity of the expert weight method. The risk assessment model is applied using the Xiangjiang shield tunnel as an example. The results show that the overall construction risk level of the Xiangjiang tunnel is level II, which is consistent with the site risk situation and shows that the model can objectively and accurately evaluate the construction risk level of an underwater shield tunnel. Keywords. degree.
Underwater shield tunnel; risk assessment; cloud model; entropy weight method; determination
1. Introduction With the ongoing construction and development of urban metro tunnels, river-crossing and sea-crossing traffic tunnels, water conservancy and hydropower tunnels and municipal utilities tunnels, many tunnels need to cross rivers to meet the needs of regional economic development. Many underwater tunnel projects have been successively built in this century. According to statistics, more than 20 underwater tunnels, including those used for subways and highways, have been planned in the Yangtze River basin in China. With the improvement of shield technology, shields have occupied a major position in world tunnel construction, especially in underwater tunnels [1]. While facing underwater tunnel engineering, the shield tunnelling method has become the preferred construction method for tunnel construction because of its advantages of high mechanization, fast tunnelling speed, low environmental impact and safe construction. However, many uncertainties remain in the underwater tunnel c
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