既有旧桥梁组合式护栏事故分析与解决方案

Analysis and Resolving Method of the Existing Old Bridge Built-up Guardrail Accident

早期公路上建造的桥梁组合式护栏已不满足新交通环境下的防护需求,需要进行升级改造。为提高既有旧桥梁组合式护栏的安全防护性能,首先结合事故形态分析,提出护栏破坏模式,包括发生在跨中碰撞的破坏模式I和发生在立柱碰撞的破坏模式II,基于此通过极限抗力计算,护栏上部钢结构(横梁和立柱)设计强度偏弱;进一步对既有护栏安全防护性能进行碰撞分析,护栏不满足评价标准安全性能指标要求;最后综合考虑护栏改造的经济性、景观性及施工方便性,提出了一种加强钢结构组合式桥梁护栏方案,通过采用实车足尺碰撞试验对方案的安全性能进行评价,结果表明:加强改造后的桥梁组合式护栏安全性能指标包括阻挡功能、导向功能和缓冲功能均满足《公路护栏安全性能评价标准》(JTG B05-01-2013)要求,具备SS级(520 kJ)的防撞能力。该方案具备高防护等级,且施工方便、景观较好,取得了良好应用效果。

The highway bridge built-up guardrails built in early stage have been unable to meet the protection requirements of the new traffic environment,which needs to be upgraded.In order to improve the safety of the existing old bridge built-up guardrail,Firstly,the failure modes(including the failure mode I in mid-span collision and the failure mode II in column collision)of the guardrail was put forward combined with the accident form analysis,and the design strength of the steel structure above the guardrail(the beam and the column)is weak through the calculation of limit bearing capacity;Furthermore,The collision analysis was carried out on the protection performance of the existing guardrail,and the guardrail does not meet the safety index requirements of the evaluation standard;Finally,the solution of reinforcing the steel structure above the guardrail was proposed with considering the economy,the landscape and the construction convenience of the guardrail reconstruction comprehensively,then the performance of the scheme was evaluated by the full-scale impact test with real vehicles,and the results show that the safety indexes of the scheme including the interception function,the guidance function and the buffer function can meet the requirements of standard for safety performance evaluation of highway barriers(JTG B05-01-2013),and the guardrail modification structure reaches SS Level(520 kJ).Because of the high protection level,the convenient construction and the good landscape,the guardrail modification scheme has the good promotion and application.