Study On Speed Limit Of The Dark Ice Of The Entrance And Exit Of The Tunnel

In recent years,China has made great achievements in highway mileage and number of tunnels.Meanwhile,tunnel traffic safety has been more and more serious due to the natural environment and operating conditions.The entrance and exit of the tunnel traffic safety is being taken into consideration,and the tunnel speed limits is the focus of attention.Based on traffic safety and long-term use of road to determine their speed limit values.The main contents of this article are the following:Firstly,this article study on the formation dark Ice and its mechanism and vulnerable area.Then,based on Qinling Mountain area highway entrance and exit of the tunnel,and combination of early weather information by collection and inspection of the tunnel,we analysis the entrance and exit of tunnel to determine its effects to the dark Ice.And based on the relationship between the road surface temperature and formation of dark ice,we determine the entrance and exit of tunnel transition area length.This transition area length is the main area to against the dark ice,and it's the area where the follow-up model simulation and finite element analysis are made.Secondly,according to the study on road surface temperature characteristics of the entrance and exit of tunnel,and based on the coupling relationship between vehicle and road,we further analysis on the relationships between the vehicle speed and driving stability of entrance and exit of tunnel section.And according to the vehicle-road model,we determine the vehicle speed limit values based on stability of traffic safety.And on this basis,we further study on the relationship between different speeds of vehicles and the different stress of roads,and find the relationship between different speed and road stress,and then establish a relationship between speed and road fatigue stress to provide the reliable assurance to determine speed limit values based on the long-term road use.First of all,applying contact Element Theory,we find the laws of pressure distribution of contact surface.Secondly,because of roughness of pavement and speed of vehicles will not only affect vehicle vibration characteristic values,but also affect the Random Load which wheels exert on the pavement,leading to a certain level of change of wheel load.So,by using Finite Element Theory and the theory of contact elements,we find the relationship between different speed and road stress.Finally,by using Finite Element Theory to analysis the entrance and exit of tunnel.And we come to a conclusion of relationship between different speed and road force.And the force main concern about the way friction and air resistance.Then,based on the second chapter of the analysis of pavement temperature characteristics of the entrance and exit of tunnel,we built the finite element model of the entrance and exit of tunnel.Through the different stress models to analysis the stress and strain change of dark ice and road surface of entrance and exit of tunnel under different speeds.By contrast it with the limit damage strain and stress of dark ice and road pavement,we can determine the vehicle limit speed of entrance and exit of tunnel.And based on the road damage and Chapter III of the traffic safety,we can determine the final speed limitation of entrance and exit of tunnel.Because the model established have considered other common characteristics of the tunnel,we can assure that the speed limit values can apply to other tunnel's speed limitation,not just confined to the tunnel selected by the chapter two.