Study On Safety Risk Assessment And Application Of Highway Tunnel Construction

In recent years,with the rapid development of highway transportation industry in China,more and more highway tunnels have been put into construction.The construction stage of highway tunnel is complex,difficult and risky.The light will affect the progress of construction,while the heavy will cause casualties.Therefore,it is of great necessity and practical significance to carry out safety risk assessment in the construction stage of highway tunnel engineering.Firstly,the system of safety risk assessment of highway tunnel construction is understood from theory,and the composition and construction technology of highway tunnel are compared and analyzed.Finally,the NATM is selected to carry out the research on safety risk assessment of highway tunnel construction.Then,in order to obtain the risk factors in the construction of highway tunnels,the construction sites of 25 typical highway tunnels were investigated on the spot.Through visiting relevant experts,the risk factors were identified from human,machine,material,method and ring,and the summary table of risk factors analysis was obtained.Statistics and analysis of 150 construction accidents occurred in highway tunnels in China in the past 20 years,summarize the basic classification of accidents,accident characteristics and influencing factors of typical accidents,further improve the risk factors of highway tunnel construction,and divide them into six categories.Secondly,on the basis of identifying risk factors and combining with literature research,the index system of highway tunnel construction safety risk assessment is preliminarily established,and the index system is finally determined by optimizing the evaluation index system through information entropy method.Through relevant normative content and literature research,the classification standard of highway tunnel construction safety risk grade is determined.Further classification and interval quantitative risk assessment indicators are carried out,and specific criteria for evaluating indicators are obtained.Thirdly,it is determined that the performance and prediction results are both excellent by comparing the traditional and new methods in the field of tunnel engineering safety risk assessment,and that the RBF neural network with better applicability for the safety risk assessment of highway tunnel construction is optimized to carry out the assessment work.The probability prediction model of road tunnel construction safety risk based on RBF neural network optimized by PSO is established by matlab.The distribution law of total risk loss grade of road tunnel construction under different lengths is obtained by expert investigation method.Finally,the risk assessment model of road tunnel construction safety based on RBF neural network optimized by PSO is obtained.On this basis,a safety risk assessment software for highway tunnel construction is designed using the VS.NET platform.Finally,taking Longquankou Tunnel in Hebei Section of Yanchong Expressway as an example,the overall safety risk level is "severe".The safety risk levels of collapse and water gushing(mud)in the left ZK23+720～ZK24+470 and the right K23+720～K24+510 sections are "moderate",which are consistent with the actual construction situation of Longquankou Tunnel.This further illustrates the effectiveness of the safety risk assessment software developed.It provides a good reference for the application of safety risk assessment of highway tunnel construction in practical engineering.