近断层高速铁路典型桥梁抗震优化设计研究

Optimization Design of Typical High-speed Railway Bridge in Near-fault Seismic Zone

研究目的:西南山区某高铁穿过现今非常活跃的小江断裂带,设防烈度高达九度。高地震烈度和近断层脉冲效应对铁路桥梁的抗震设计和高速列车行车安全提出了更高的要求。基于此,本文通过分析近断层地震激励下典型高铁桥梁的弹塑性动力响应规律,开展桥梁减隔震装置和桥墩设计参数优化研究。研究结论:(1)桥墩在近场地震动作用下轴力变化较大,对桥墩的承载能力产生较大的影响,在抗震设计中应予以考虑;(2)采取本文提出的优化设计流程能够使得桥墩在整个墩高范围内纵桥向和横桥向具有相近的安全储备,并充分发挥混凝土和钢筋两种材料的性能;(3)采用摩擦摆支座+限位耗能杆的减隔震体系具有良好的减隔震效果,内力减震率可达20%以上;(4)若允许支座销钉在多遇地震时剪断,可使多遇地震下墩底内力进一步降低11%~45%,由此降低的梁体横向加速度和增大的位移响应对行车安全性影响应进一步结合车桥耦合振动分析确定;(5)本研究成果可为高铁典型桥梁抗震设计提供参考和依据。

Research purposes:A certain high-speed railway in the southwest mountainous in China passes through the very active Xiaojiang fault zone,and the seismic fortification intensity is as high as nine degrees.High seismic intensity and near-fault pulse characteristics put forward higher requirements for the seismic design of railway bridges and the safety of high-speed trains.The elasto-plastic seismic response of the typical high-speed railway bridge under the near-fault ground motion is studied.Then optimum parameters design of the seismic isolation system and pier are carried out.Research conclusions:(1)The axial force of the piers in the near-fault seismic zone changes greatly under the action of ground motion,which has a great influence on the bearing capacity of the pier.Special attention should be paid in the seismic design.(2)The optimization process proposed in this paper can make the pier have a proportionable safety reserve for both the longitudinal and transverse direction in the entire height range and make the performance of the concrete and steel bars can be fully utilized.(3)The effect of using vibration isolation system with friction pendulum bearing and damper is remarkable,and the internal force decreasing rates can reach more than 20%.(4)If pin of the bearing can be cut in advance of low-level earthquake,the internal force of the pier-bottom can be reduced by 11%to45%,which may simultaneously improve the safety of high-speed trains.However,the effects of reduced lateral acceleration and increased displacement response on the safety of high-speed trains under seismic excitation should be further studied combined with vehicle-bridge coupling vibration analysis.(5)This research result can provide reference for seismic design of the high speed railway bridges.