Research On Safety Risk Management And Countermeasures For Construction Of Segmental Prefabricating Cantilever Assembling Beams

With the accelerated urbanization and the rapid development of prefabricated assembly construction,segmental prefabrication and assembly construction technology is being widely used in the construction of urban bridges,and this technology is well suited to meet the needs of urban bridge construction development and improve the construction level of modern bridges.The factory prefabrication of girder sections can greatly improve the quality of concrete and reduce the pollution of the bridge environment,and keep the traffic flowing under the bridge can also ease the traffic pressure,which presents its technical advantages in terms of construction quality,duration,economy and applicability,and has a broad development prospect.However,segmental prefabricating cantilever assembling construction technology is in the development stage in China,the technical complexity of the construction process also increases the difficulty of safety management in the bridge construction process,risk management research can reduce the possible accidents in the construction,avoid causing huge economic losses,while improving the construction management level,has important practical significance.In order to carry out the evaluation study on the risk of segmental prefabricating cantilever assembling beams during the construction stage,firstly,we analyzed and identified the potential risk factors that may exist in the construction process by combining the characteristics of segmental prefabricating cantilever assembling beams and relevant information of similar projects,and established the initial evaluation index system.Then,in order to further improve the accuracy of the evaluation indexes,the importance of the initial indexes was investigated,and the cumulative information contribution rate and partial correlation analysis are used to eliminate the indicators that have no significant impact and reflect duplication of information.Finally,after screening,a construction safety risk evaluation index system was established with the basic contents of construction environmental risks,construction personnel safety risks,construction technology risks,construction machinery risks and safety management risks.On the basis of the risk evaluation index system,combined with the complexity and uncertainty of the safety risk of segmental prefabricating cantilever assembling beams,the COWA(Combination Ordered Weighted Averaging)operator weighting method is selected to determine the index weight,and the weighting results are referred to the calculation of risk probability and loss quantification values,the risk probability quantification model based on the weighted fault tree and the risk loss quantification model based on fuzzy comprehensive evaluation are established.The risk loss considers five aspects: economic loss,life loss,construction period loss,environmental loss and social loss.Finally,combining the risk probability and the loss quantification value,the risk measurement value is obtained,and based on this,a comprehensive risk evaluation model based on the D-S(Dempster/Shafer)evidence theory is established,and evidence fusion of high conflict data information is carried out to effectively deal with the uncertainty problem under multiple evidence.Finally,this evaluation model is used to verify the project,through the risk measurement and grade definition,based on the result of evidence information fusion,the overall risk level of the project is obtained,and the reliability and operability of the model are tested.And based on the evaluation results,the necessary risk prevention countermeasures for high-risk factors are proposed,which can provide a certain reference for the management and control of the safety risk of this type of bridge construction.