Research On The Improvement Of NJ Guardrail Protection Ability

Crash barrier is one of the most important traffic safety facilities on the road,which plays a key role in reducing the severity of road traffic accidents and economic losses.The main highway guardrail in our country has entered the stage of overhaul,maintenance and expansion.The common transformation method is to install new guardrail or reinforce the old guardrail.The installation of new guardrails will cause problems such as inconvenient construction and waste of resources.Therefore,it is an important task to reconstruct the old guardrail reasonably and upgrade it to meet the requirements of the new code.Due to the annual overhaul of the national and provincial trunk lines in a city,the elevation of the road surface continues to increase,resulting in the original NJ type guardrail height can not reach the original design height,and the protection capacity decreases.This paper explores the heightening scheme of NJ type guardrail on the national and provincial trunk roads in a city to ensure that the guardrail after heightening meets the protection requirements.Because the protective ability of guardrail is directly related to its section form,firstly,the standard NJ guardrail and straight arm guardrail are simulated by minibus,and the advantages and disadvantages of the two guardrails are evaluated from the aspects of guardrail safety performance,anti-collision performance and guidance performance.The simulation results show that the minibus and the minibus in the collision process of the two guardrails pass normally without crossing or riding over the guardrail Phenomenon: in the process of collision between the minibus and two kinds of guardrails,the minibus is normally exported,and the driving track is within the range of driving out block diagram.Both kinds of guardrails have good guiding function.In the process of collision between minibus and NJ guardrail,the acceleration and collision speed of passengers after collision meet the specification requirements,NJ guardrail has high safety performance,while in the process of collision between minibus and straight wall guardrail,the acceleration after collision of passengers exceeds thespecification requirements,and the safety performance of straight wall guardrail does not meet the specification requirements,so the reconstruction method of retaining the original section of guardrail is adopted.Secondly,the heightening method of NJ guardrail is determined according to the actual situation.After heightening,the NJ guardrail is simulated by finite element method.The acceleration of vehicle center of mass,the acceleration of passengers,the running track of vehicle,the damage of vehicle and the structural integrity of guardrail are used to make the heightening scheme of NJ guardrail feasible The results are verified.Finally,according to the relevant evaluation standards and test data,the conclusion of NJ guardrail heightening scheme is feasible.This research can provide reference for the selection of guardrail form and the heightening scheme of guardrail.