Study On Tower Construction Safety Risk Evaluation And Control Of Long-span Cable-stayed Bridge Based On Complex Network Theory

Cable-stayed bridges have large spans and beautiful shapes.The main girder can be made into beams of equal cross-section,which is easy to manufacture and install.The investment in the construction of transportation infrastructure has increased,and it has become widely used in engineering practice.The cable tower of the long-span cablestayed bridge across the Yangtze River is a high-rise structure with a large shape.It not only has the technical and economic characteristics of long construction period,nobracket climbing slip form construction of the main tower,high-altitude operation on water,three-dimensional crossing operation,narrow operation platform.And it is very sensitive to weather factors such as wind,temperature difference,thunder and lightning.The interaction of man-machine,material and environmental factors in construction determines the complexity and risk of the safety of the pylon construction.As the span of cable-stayed bridge increases,the height of the cable tower increases,and the construction safety risks become more and more complicated.The requirements for the safety risk assessment and control management of the construction of the cable tower are also getting higher and higher.However,in the current engineering practice,the special design for the construction safety of the pylon is mainly aimed at the development of safety measures for the construction process.It lacks a comprehensive analysis of the formation of safety risks and the traceability analysis of the coupled risks.The theoretical research is relatively weak,and it does not meet the requirements of increasing safety risks in cable tower construction.From the perspective of complex system risk analysis theory,this paper analyzes and studies the factors that affect the safety risks of the tower construction and the complex coupling effects of safety risks,establishes a safety risk assessment model,and realizes the safety risk assessment and control of the construction of the tower.This is not only of great significance for improving the theory of safety risk management in the construction of pylons,but also of important practical value for guiding engineering practice and ensuring the realization of project construction goals.In view of the existing problems of safety risk management in the construction of the towers of long-span cable-stayed bridges in our country,this paper deeply studies the construction of the towers of the cable-stayed bridges.Using the literature analysis method from the five aspects of human,machine,material and environmental management,combined with the characteristics of the construction technology of the pylon,it is established from the five aspects of the quality of the operators,the formwork support system,the lifting and transportation,the safety of the high-altitude workers,and the quality of reinforced concrete to make security risk list.Based on the complex network theory,it identifies the coupling relationship between risk factors,and constructs a complex network graphical model of the safety risk coupling of the tower construction.Then,based on the ranking theory of node importance in complex networks,this paper designs network evaluation indicators,including self-risk strength,out-risk coupling strength,in-risk coupling strength,weighted aggregate risk strength,and medium-risk strength,to characterize complex network characteristics such as the magnitude of risk,coupling relationship,risk transmission.On this basis,integrating gray correlation analysis and multi-attribute decision-making,a GRA-TOPSIS-based long-span cablestayed bridge tower construction safety risk coupling network evaluation model is established,and specific algorithms are designed to realize the analysis of the importance of security risk factors.On the basis of risk evaluation,combined with the coupling theory,the safety risk management and control measures of the tower construction are proposed from three perspectives: before risk coupling,during risk coupling,and after risk coupling.Finally,this paper applies the GRA-TOPSIS-based pylon construction safety risk coupling network evaluation model to the Fengdu Yangtze River Second Bridge Project.Among them,inadequate safety management ranks the highest among safety risks for high-altitude workers.The results show that the risk assessment model constructed in this paper has strong operability and applicability,and provides a reference for advancing the engineering practice of safety risk management in the construction of long-span cablestayed bridges in my country.