Research On Risk Assessment Of Swivel Construction Of PC Box Girder Bridge Over Railway Line

Over the past 40 years of reform and opening up,my country’s bridge construction level has advanced by leaps and bounds,bridge construction technology ranks among the top in the world,various transportation networks have been continuously improved,and the number of three-dimensional crossing projects has been increasing.The swivel construction technology has the advantages of economy,speed,and does not affect the existing traffic,and is widely used in overpasses.However,due to the complex construction process of the swivel bridge,the difficulty in controlling the swivel stability,and the multi-dimensional uncertain risk sources,construction risk accidents often occur.In order to effectively prevent and avoid the occurrence of safety accidents in swivel construction,this paper takes swivel construction PC box girder bridges as the research object,and conducts research on construction safety risk assessment theory,methods and prevention and control technologies,aiming to establish a set of suitable PC box girder bridges.The risk assessment system of bridge swivel construction,the specific research contents include:(1)Based on the existing risk management theories,the relevant concepts of risk,risk identification,risk assessment and risk control are summarized,the general bridge construction risk identification and risk assessment flow chart is clarified,and the principles that should be followed in formulating risk control measures are summarized.(2)Analyze the common construction schemes for PC box girder bridge swivel construction,and comprehensively identify primary and secondary risk sources in combination with expert investigation methods.Based on this,build an analytic hierarchy process model for risk sources;coupled with cloud model to improve the analytic hierarchy process,use MATLAB to write optimize the algorithm,calculate the weight value of each risk source,and finally determine the expected risk source weight value with the help of cloud model numerical simulation;introduce four elements of casualties,economic loss,time loss and social impact to improve the traditional LEC method,and propose an optimized LEC method,using This method determines the risk level and loss degree of the risk source;finally,the fuzzy comprehensive evaluation method is used to evaluate the overall risk level of the swivel construction.(3)Based on the swivel construction project example,the feasibility and accuracy of the established PC box girder bridge swivel construction risk assessment system are verified.Based on the existing specification requirements,combined with the risk assessment results of the swivel bridge construction,risk prevention and control measures to ensure the safety of the whole process of bridge construction are formulated.(4)In order to reduce the probability of risk occurrence,combined with the conclusions of risk assessment,the construction technology of the swivel bridge was innovated,and a new type of swivel bearing with lugs was developed,so that the tension force of the continuous tension jack acts on the turntable in a smoother way On;invented the intelligent rectifying roller support feet,monitoring the vertical displacement of the beam body rotation,self-adjusting the bridge rotation posture,to ensure the safety of the rotation construction.Using ABAQUS to study the mechanical properties of the support feet,predict the working conditions of the support feet’s rotation;develop the auxiliary support feet to support the tire frame to ensure the stability of the support feet before the rotation construction;And applied to engineering entity projects to test the practicability of the new technology.