重载铁路水冲受损桥墩适应性分析及加固控制技术

Adaptability Analysis and Reinforcement Control Technology of Scour⁃damaged Pier of Heavy Haul Railway

以受洪水冲刷的一座重载铁路浅基桥墩为对象,基于现场试验、数值模拟、在线监测等方法,研究大轴重运输条件下冲刷程度、荷载类型等因素对水冲受损桥墩刚度、稳定性和动力响应的影响。基于安全运营需求,提出一种实时监测+定期监测的加固施工安全监控方法,并开展实际工程应用研究。结果表明:冲刷引起墩台基础土体流失和约束降低,导致桥墩刚度减小、稳定性下降和振动加剧;随着冲刷深度增加,桥墩与主梁振动响应逐渐增大,桥墩自振频率逐渐降低;大轴重列车作用下,随着列车速度和轴重增加,桥梁振动响应逐渐增加,桥梁振动响应与列车速度、轴重均成线性关系。对结构振动响应和墩台变位进行加固施工安全监控,发现加固过程中基础开挖和冲击钻孔是关键施工控制环节,且导致了桥梁横向振动显著增加,而基础加固施工对桥墩结构横向振动影响较小,且各项施工内容对结构沉降、水平位移和纵向振动的影响相对较小。

Taking a shallow foundation bridge pier of a heavy haul railway that was scoured away by floods as the object,based on on-site tests,numerical simulations,online monitoring,and other methods,the effects of factors such as scour degree and load type on the stiffness,stability,and dynamic response of bridge piers scour-damaged under large-axle load transportation conditions were studied.Based on the needs of safe operation,a real-time monitoring and regular monitoring method for reinforcement construction safety monitoring was proposed,and practical engineering application research was carried out.The results indicate that scour causes soil loss and reduced constraints on the pier foundation,leading to a decrease in pier stiffness,stability,and increased vibration.As the scour depth increases,the vibration response of bridge piers and main girders gradually increases,and the natural frequency of bridge piers gradually decreases.Under the action of a large-axle load train,as the train speed and axle load increase,the bridge vibration gradually increases accordingly.The bridge vibration response is linearly related to the train speed and axle load.Through safety monitoring of structural vibration response and pier displacement during reinforcement construction,it was found that foundation excavation and impact drilling are key construction control links during the reinforcement process,leading to a significant increase in bridge transverse vibration.However,foundation reinforcement construction has a relatively small impact on the transverse vibration of the bridge pier structure,and the impact of various construction contents on structural settlement,horizontal displacement,and longitudinal vibration is relatively small.