Study On Crash Simulation And Reconstruction Of W-Beam Guardrail On National And Provincial Roads In Mountainous Areas

In recent years,with the rapid growth of China’s social economy and the continuous development of the transportation industry,many highway infrastructure safety facilities built in the past have the problem of aging and need to be replaced,and gradually cannot fully meet the current safety protection requirements of traffic roads.As a passive roadside safety protection facility,corrugated beam guardrails play a crucial role in road safety.They also have the problem of being used for a long time and being damaged.Especially for ordinary national and provincial highways located in the mountainous areas of western China,roadside traffic safety facilities urgently need to improve their protection capabilities.According to the 2006 edition of the "Code and Rules for the Design of Highway Traffic Safety Facilities" in China,the Class-A w-beam guardrail shall use a two-wave corrugated beam plate,while the current "Code and Rules for the Design of Highway Traffic Safety Facilities" issued in 2017,the Class-A w-beam guardrail shall use a three-wave corrugated beam plate.In the replacement of guardrails,the complete removal of the original Class A guardrail will cause a waste of resources,which is not in line with the development trend of "green transportation" in China.Moreover,the removal and reinstallation of guardrails will take a long time,which will affect transportation.Therefore,this paper proposes a guardrail that is upgraded based on the unchanged original Class A corrugated beam guardrail,and conducts finite element simulation analysis and evaluation of the protective performance of the original guardrail and the modified guardrail to verify whether the modified guardrail meets the specification requirements in the simulation test.The main research contents include the following three aspects:(1)Through the finite element simulation method,the corrugated beam plate model,the anti blocking block model,and the column model were established,and the solder joint connection mode of each component of the guardrail was determined.A complete finite element model of the original Class-A w-beam guardrail was established.The passenger car model,bus model,and truck model are selected as simulation collision test vehicles.The reliability of these three vehicle models is verified through the frontal collision test between the vehicle model and the rigid wall.The boundary conditions,contact types,time steps,hourglass energy,output control,and impact force load application parameters of the collision model were set,and a complete finite element model for vehicle guardrail collision simulation was established by coupling the collision system of the vehicle model and the guardrail model.(2)Discussed whether the original Class-A w-beam guardrail can meet the due blocking,buffering,and guiding functions under the working condition of increasing the road surface by 50 mm.Using Hyper View software,analyze the collision simulation results of the original A-level guardrail model and three vehicle types,and analyze the data in the results such as vehicle trajectory,vehicle center of gravity height changes,collision force changes,vehicle center of gravity speed and acceleration changes during the collision process,vehicle dynamic camber values,displacement and stress changes of the guardrail model.The maximum camber values of buses and trucks are 2260 mm and 2013 mm respectively,and the vehicle model leaves the guardrail protection area,the results show that the protective capacity of the original Class A guardrail for buses and trucks is insufficient.(3)According to the differences between the new and old specifications for Class A w-beam guardrails,as well as the investigation and analysis of actual engineering projects,a comprehensive transformation scheme is proposed,which increases the overall height of the guardrail by 400 mm,and densifies the column spacing from 4m to2 m.That is,the existing double wave corrugated beam slab is still used,and the embedding position of the original column is not changed.This transformation scheme can fully utilize the resources of the existing corrugated beam guardrail,facilitating construction,Less impact on road traffic.A finite element model for collision simulation between the modified guardrail and the models of passenger cars,buses,and trucks was established.Based on the collision simulation results of the modified guardrail and three types of vehicle models,the vehicle running trajectory,changes in the height of the vehicle center of gravity,changes in the collision force,changes in the velocity and acceleration of the vehicle center of gravity during the collision,and dynamic camber values of the vehicle were analyzed under the road surface elevation of 50 mm Based on the displacement and stress changes of the guardrail model,study whether the reconstructed guardrail can meet the required blocking,buffering,and guiding functions.The maximum collision speed and acceleration of the small passenger car are 5.9m/s and 137m/s2,respectively,meeting the requirements of the regulations.All three types of vehicles have not left the guardrail and returned to the original direction of travel on the road,The results show that the modified guardrail scheme can effectively protect three types of collision vehicle models,and has the blocking,buffering,and guiding functions required by the specification for Class A guardrails.Based on the above research,this thesis concludes that the protective performance of the reconstructed guardrail based on the original Grade A guardrail meets various evaluation indicators and corresponding specifications,and the comprehensive protective performance of the reconstructed guardrail is more excellent than the original Grade A guardrail.