Research On Characteristics Of Urban Small Radius Curve Tunnels And Safety Guarantee Technology

The special natural geographical environment in mountainous areas determines that road construction standards should be adapted to local conditions.In order to overcome large height differences and avoid unfavorable geological zones,etc.,small radius curve tunnel schemes have become more and more widely used.However,because small radius curve tunnels at home and abroad are rare,and the relevant specifications also lack specific requirements,therefore,research on traffic characteristics and traffic safety technology of small radius curve tunnels is of great significance to the operational safety of tunnels in China.This article first analyzes the radius values of urban small-radius curve tunnels:through field investigations,the difference between the offset values of vehicles traveling in small-radius curve tunnels and straight-line tunnels is analyzed,and the differences in the offset values of the different lanes on the up and down lanes of small-radius curve tunnels are analyzed;Using the offset threshold of the small radius curve tunnel,combined with the driving stability of the vehicle and the driver’s line of sight to define the urban small radius curve tunnel.Secondly,the different characteristics of the small radius curve tunnel are analyzed.(1)Through practical investigation,analyze the linear characteristics,accident characteristics,environmental characteristics,traffic operation characteristics and physiological and psychological characteristics of small radius curve tunnels,and focus on the characteristics of speed and illumination on the driver’s psychophysiological characteristics in the tunnel.(2)By investigating the illuminance of 6 different linear tunnels in Chongqing,the lighting characteristics of small radius curve tunnel and ordinary straight tunnel are compared and analyzed,and their changing rules at the tunnel entrance are summarized.Dialux was used to analyze the illuminance change of small radius curve tunnels in different seasons and at different times of the opening,and the dark adaptation start point and dark adaptation end point for small radius curve tunnels were proposed,and the safe speed based on dark adaptation distance was proposed according to examples.Based on the lighting design of Changhe Road’s small radius curve tunnel,and using Dialux to simulate and analyze the three kinds of lamp arrangement methods of center line layout,symmetrical layout on both sides and sideline lateral layout,from total uniformity,longitudinal uniformity and brightness The comparison of the three indicators shows that the centerline deflection can better meet the small radius curve tunnel.(3)Analyze the driving load characteristics of small radius curve tunnel.Carry out a real car test on the driving load of a small radius curve tunnel in the city,and collect the changes of the driver’s heart rate in the tunnel under different illuminances and speeds.Using statistical principles to analyze the changes in heart rate growth rate of small radius curve tunnels and ordinary tunnels at different speeds and illuminances,and establish a regression model of heart rate growth rate and speed illuminance;it is concluded that the driving load of small radius curve tunnels exists as ordinary straight tunnels Significant difference,the sensitivity of the driving load of the small radius curve tunnel is significantly greater than that of the ordinary straight tunnel.Finally,according to the environmental characteristics,vehicle operation characteristics,illumination change characteristics and driving load characteristics of the small radius curve tunnel,the transition section of the small radius curve tunnel entrance is 80 m outside the tunnel to 110 m inside the tunnel.Safety noise reduction facilities;then from the speed limit technology,the safe driving speed of different sections of the small radius curve tunnel based on the heart rate growth threshold is proposed,and from the visual induction technology,the reflective ring and asymmetric edge rate scale suitable for the urban small radius curve tunnel are proposed Line settings.