基础加固施工对重载铁路桥梁静动力性能影响研究

Study on the Influence of Foundation Reinforcement Construction on the Static and Dynamic Performance of Heavy Haul Railway Bridge

铁路桥梁墩台基础加固施工会改变桥墩约束状态,影响结构稳定和列车运营安全。以某重载铁路轻型桥墩基础加固工程为背景,采用数值模拟和试验测试手段,研究各关键施工环节对桥墩和桥跨结构稳定性、刚度和振动响应的影响规律。研究结果表明,基础加固施工分为钻孔桩施工、基础侧土体开挖、基础混凝土浇筑、墩身连接等4个关键施工步骤,其中土体开挖会导致桥墩稳定性和横向刚度降低,随开挖深度增加,两者均逐渐降低,而混凝土浇筑则引起桥墩刚度和稳定性逐渐增加,桥墩横向连接加固则引起墩身刚度显著增大,增幅达到32%;整个施工阶段中,土体开挖引起桥梁结构振动响应显著增大,其他加固环节对桥梁振动响应不明显;施工过程中,列车轴重、速度、桥墩高度是影响桥梁动力响应的最敏感因素,随列车轴重和速度以及桥墩高度增加,桥梁动力响应增大明显。

Reinforcing the foundation of a railway bridge pier will change the constrained state of the pier and affect the stability of the structure and the safety of train operations.In this paper,based on the foundation reinforcement project of a light pier of a heavy haul railway,the influence of each key construction link on the stability,stiffness and vibration response of pier and bridge span structure was studied by means of numerical simulation and experimental test.The research results show that the foundation reinforcement construction is divided into four key construction steps:bored pile construction,foundation side soil excavation,concrete pouring and pier transverse connection.Among them,soil excavation will lead to the decrease of pier stability and transverse stiffness.With the increase of excavation depth,both of them gradually decrease,while concrete pouring will cause the pier stiffness and stability to gradually increase,and pier transverse connection reinforcement will cause the pier stiffness to increase significantly,with an increase of 32%;In the whole construction stage,the vibration response of the bridge structure caused by soil excavation increases significantly,while the vibration response of other reinforcement links to the bridge is not obvious;During the construction process,the train axle weight,speed,and abutment height are the most sensitive factors affecting the dynamic response of the bridge,which increases significantly with the increase of train axle weight and speed and abutment height.