铁路桩基础桥墩基底隔震摇摆模型试验研究

Model Test of Rocking Seismic Isolation of Railway Bridge Pier with Pile Foundations

为了探究桥墩基底摇摆隔震技术在铁路桩基础桥梁中的应用效果,首先提出了无约束自由摇摆和设置限位钢筋约束摇摆两种不同的桥墩基底摇摆隔震模式.其次按照1∶10的比例制作了桥墩及桩基础缩尺模型,采用拟静力试验方法分析了两种不同摇摆隔震桥墩模型的破坏特征、滞回曲线、骨架曲线以及桩身应变等性能参数.试验结果表明:两种基底摇摆隔震桥墩模型均能够有效改善桩基础桥墩的力学特性和抗震性能,相对于自由摇摆隔震桥墩,约束摇摆隔震桥墩中增加的限位钢筋,可以有效地提高摇摆隔震桥墩在正常使用阶段或较小水平地震作用时的横向刚度和稳定性.通过对桩基础的应力分析发现:采用无约束自由摇摆和限位钢筋约束摇摆的两种隔震模型的桩身应变值均较小,说明两种桥墩基底的摇摆隔震措施均可以有效保护地震作用下的桩基础.此外,通过分析发现限位钢筋不仅提高了桥墩在摇摆过程中的抗倾覆能力,并且具有明显的耗能特性.

In order to investigate application effects of the rocking seismic isolation technique for railway bridges with pile foundation,the seismic isolation pier model with free rocking and controlled rocking by inhibiting steel bar were presented in this study firstly.Then,quasi-static tests for two 1/10-scale model piers were performed to analyze failure modes,hysteretic behaviors,skeleton curves and pile stresses of the two different models.Through the testing results,it can be concluded that both the two rocking seismic isolation techniques can improve the mechanical properties and seismic performance of the bridge piers with pile foundation.Compared with the free rocking model,the controlled rocking model with inhibiting steel bar can significantly increase the lateral stiffness and stability of the bridge pier under normal service stages and small earthquakes.The results also showed that the pile shaft strains of the two model are relatively small,which indicates that the rocking seismic isolation of bridge pier is beneficial for pile foundation under seismic action.Besides,analyses showed that the inhibiting steel bars not only can improve the anti-overturning capacity of rocking bridge piers,but are beneficial for energy dissipation.