Risk Analysis And Countermeasure Study On Construction Process Of Super High Pier T Frame Bridge Under Complicated Environment

As the transportation network in the inland plains becomes more and more perfect,the center of gravity of highway and bridge construction gradually extends to the western mountainous areas.Continuous rigid frame bridges are often favored when choosing bridge types across valleys and ravines due to their advantages of high rigidity,good integrity,and low maintenance costs.The ultra-high pier T-frame bridges built in high-altitude mountain areas are often in complex environments such as high wind force and large temperature and humidity differences.The construction process faces greater risks and must be given sufficient attention.In order to reduce the probability of safety accidents in the construction of such bridges,it is necessary to carry out risk assessment work.This article takes the risk of the construction process of the super high pier T-frame bridge as the main research object in a complex environment,and focuses on the following aspects:(1)Researched the concept of risk,analyzed and summarized the methods of common risk identification,the scope of application of common risk assessment methods,their advantages and disadvantages,and the classification of risk response measures.It summarizes the possible risk factors in the construction process of super high pier T-frame bridge.(2)Aiming at the shortcomings of common risk assessment methods,a comprehensive risk assessment method based on game theory and BP neural network is proposed,and this method is used in the safety risk assessment of the construction of the main pier of the Ponnazi Bridge.The result determines that the project risk is a lower risk,The risk is acceptable.The main risk factors are the pier verticality,wind load,sunlight temperature difference,and concrete strength.It is recommended that the key risk control for the construction of the high pier of the Ponnazi Bridge is the control of the pier verticality.(3)Use the finite element-Monte Carlo method to conduct risk assessment on the construction safety of the Ponnazi main beam,establish the state equation based on the maximum cantilever end deflection error,and the risk parameters as variables,and establish unequal levels according to the importance of the risk parameters Orthogonal design table,approximate the probability of occurrence of each risk level by BP neural network model.As a result,the project was judged to be a medium risk,which needs attention.The main risk factors are unbalanced load,elastic modulus of concrete,and bulk density.It is recommended that the construction risk control of the main beam of the Ponnazi Bridge be controlled by unbalanced construction.(4)Based on the construction safety risk assessment results of the main pier and main girder of Ponnazi Bridge,pier body control and template inspection and correction are proposed for the main risk factors in the construction process;steel support is provided between the pier and the main girder or the mid-span The wind resistance measures of the steel frame connected between the cantilevers,of which the latter has a better wind resistance effect;the anti-freezing measures are taken on the concrete material,and the early maintenance of the concrete is strengthened;the installation and removal of the formwork,the concrete pouring,and the hanging basket Through the construction management,links such as promotion and material stacking are as balanced as possible in response to construction risks.