Safety Risk Assessment Of Pouring Concrete For Box Girder Of Super-high Interchange In Mountain Areas

In recent years,with the vigorous development of national infrastructure,the highway construction in China has developed rapidly,and the focus of highway and bridge construction has shifted from inland to mountainous areas.High-pier bridges have innate advantages in mountainous areas and canyons.Super-high interchanges in mountainous areas have begun large-scale construction.The difficulties encountered by bridge construction in mountainous areas are much greater than those in inland plain areas.In order to reduce the possibility of safety accidents in the construction of large bridges,it is necessary to carry out safety risk assessment for the construction of bridges.At present,there are few studies on the safety risk assessment of concrete box girders of super-high interchanges in mountainous areas in China.In this paper,the safety risk of cast-in-situ box girder of high pier bridges in mountainous areas is studied,and the safety risk assessment of the project is carried out by combining the existing data and MATLAB software.The main results are as follows:1)After collecting the cases of safety risk events in bridge construction in the past,eight kinds of safety risk events are obtained,among which the failure of bracket is a high-frequency safety risk event in bridge construction process.2)The advantages and disadvantages of various safety risk assessment methods are analyzed,and a safety risk assessment system is put forward which combining analytic hierarchy process,cloud theory,improved LEC method,fuzzy comprehensive analysis method and grey theory.3)A new evaluation method is used to analyze the types of safety accidents that may occur in the cast-in-situ construction of box girders of super high interchange in a mountainous area,and the risk grade of support failure is high risk.4)The improved "five-dimensional cognitive structure model" is used to analyze the special safety risk of the support project.The new method connected the grey relational degree theory and analytic hierarchy process,and using MATLAB cloud model to evaluate the risk of three support schemes in a project.The results show that the SPS portal support has the greatest risk.At the same time,the risk of support engineering in time dimension and space dimension are analyzed,which verifies that the risk analysis method based on space and time dimension is more intuitive.5)Using finite element software MIDAS to analyze the stress of the bracket in the concrete pouring stage.The results show that the stress of SPS support meets the requirements of the code under the most unfavorable load conditions,but the displacement of the SPS support under cantilever condition is slightly higher than the code value.6)This paper expounds the mechanism of risk events from the perspective of human-factors,and puts forward corresponding risk countermeasures from the aspects of human psychology,physical,quality,education and technology.