Safety Analysis And Safety Risk Assessment Of Walking-type Jacking Of Curved Steel Box Composite Beams On Mountain Highway

When the project crosses mountainous valleys,the construction method of stepby-step jacking is often adopted.However,due to the particularity of the construction method,many risks and potential dangerous factors are often accompanied during the construction process.The stress condition of steel box girder is also changing constantly during the construction process.In China,the above problems have been deeply studied during the construction of straight bridges.However,there is little research on the step-type pushing construction of curved girder bridges.Therefore,this paper takes Cuijia Bridge of Binnan High-Speed Section Ⅱ as the support to carry out construction safety risk assessment and carry out simulation analysis on the key process of jacking.This project is the step-by-step jacking construction of curved steel box composite beam on mountainous highway.The main work is as follows:(1)Make inquiries about relevant data,take Cuijia Bridge Project of the second bid section of Binnan High Speed as the support,clarify the important and difficult points in the project,introduce the characteristics of the project,and collect the necessary data for subsequent research.(2)According to the characteristics of construction procedure and combined with expert opinions,a model based on AHP and using triangular fuzzy number and modified entropic weight method to identify dangerous sources is built.(3)According to different working conditions of each stage in the construction process and in combination with construction drawings,the stress analysis of key stages in the jacking construction process is carried out by using the finite element software 3D3S,and the anti-overturning and anti-twisting forces of the beam during the jacking process are calculated.The conclusions are as follows:(1)The risk analysis model is established,the risk indexes are combined and weighted,and the risk level of each construction risk source is obtained by using the fuzzy comprehensive evaluation method.According to the calculation results,according to the principle of membership degree,among the four risk sources,the personal accident risk is a major risk source,the risk control measures and the risk monitoring items are major risk sources,the site construction conditions are general risk sources,and the overall construction process is a major risk source.(2)According to the characteristics of construction technology and special construction conditions,combined with risk analysis results and expert opinions,put forward prevention and control measures for different risk sources,ensuring the safe and stable progress of the whole project.(3)The project is simulated by using 3D 3S finite element software,the key control parameters are obtained,and the anti-overturning and anti-twisting forces of the beam during the pushing process are calculated to provide reliable inspection basis.