分级地震下跨断层高铁简支梁桥行车安全与抗震设计优化研究

以跨越走滑断层的某高速铁路八跨简支梁桥为研究对象，基于OpenSEES平台建立其考虑梁-轨相互作用的线桥体系非线性数值模型，合成平行断层方向的水平地震动，分析了不同地震动强度下桥梁结构及CRTSII型板式无砟轨道结构的损伤特性，量化评定了结构构件的地震安全性。基于规范给出的轨道水平变形控制标准，评价了不同车速下线路的行车安全性，探讨了轨道结构的优化设计。研究结果表明:断层跨及其邻跨的地震响应最大，强震下面临严峻的破坏风险；地震下轨道水平变形明显，存在行车安全隐患的位置主要集中在断层跨及其两侧邻跨梁端；增加轨道侧向挡块数量可有效降低轨道水平变形，将侧向挡块增加至每跨每线6对时，罕遇地震下，除断层跨梁端处轨道的平行转角外，其余位置的轨道水平变形指标仍能满足车速为100 km/h时的行车安全限值。

RUNNING SAFETY AND SEISMIC DESIGN OPTIMIZATION OF FAULT-CROSSING SIMPLY-SUPPORTED GIRDER BRIDGE OF HIGH-SPEED RAILWAY UNDER EARTHQUAKES WITH DIFFERENT INTENSITIES

An eight-span simply-supported girder bridge of high-speed railway was taken as a research object, which crosses a strike-slip fault. By means of OpenSEES platform, an integrated non-linear model was established by considering bridge-track interaction. The fault-crossing horizontal ground motions were synthesized and inputted. The damage characteristics of bridge and CRTS II slab ballastless track structures were discussed under different earthquake intensities, and the seismic safety of structural components was evaluated quantitatively. With code control criteria of horizontal deformation, the running safety of track was assessed under different speeds, and the optimal design of track structure was discussed. The results show that the seismic responses of the fault-crossing span and its adjacent spans are the largest, and these bridge spans face great risk of damage. The horizontal deformation of track is obvious and the positions imposing potential threats to running safety are mainly the two ends of the fault-crossing span and its adjacent spans. By increasing the number of lateral rail block, the horizontal deformation of track can be effectively reduced. For the case of 6 pairs of rail block per span and line, the deformation can still meet the safety limit with speed of 100 km/h, except for the parallel turning angles of the fault-crossing span under rare earthquakes.