考虑桩-土相互作用效应的高速铁路桥梁桩基础抗震设计方法研究

Study on seismic design method for high-speed railway bridge pile foundations considering soil-pile interaction effect

针对强震下高速铁路桥梁桩基础抗震设计中存在的问题,对桩基础的抗震性能提出了多级设防目标并给出了相应的评价指标与合理取值.借鉴FEMA440考虑桩-土三种相互作用效应的能力谱法,采用p-y、t-z及q-z曲线模拟桩周土的柔性效应,用PMM铰模拟桩身的非线性,通过Pushover分析得到桥墩的能力曲线.引入FEMA440对地基运动学效应、地基阻尼效应的地震动需求谱修正算法,对需求谱进行了修正.探讨了应用性能点轨迹法求解桩基础的延性需求及性能点的过程.以高速铁路32 m简支箱梁桥墩为研究对象,通过实例验证了该法的可行性.

In viewof the existing questions in seismic design of the high-speed railway bridge pile foundation under strong earthquakes,seismic performance of pile foundation based on multil-evel fortification goal is proposed and the corresponding evaluation index and rational values gived. On the basis of the capacity spectrum method（ CSM） put forward in FEMA440 including three kinds of soil-pile interaction effects,foundation flexible effect is simulated by using the curves of p-y,t-z and q-z,while the nonlinearity from pile members is analyzed by PMMhinge,capacity curve of the pier is obtained by pushover. By introducing a seismic demand spectrum modification algorithm from the FEMA440 considering foundation kinematics and damping interaction effects,the modification of demand spectrum is performed. The solving process of ductility demand on pile foundations and performance point is discussed by applying the performance point locus method. With one pier of32 m simply-supported box girder bridge in high-speed railway as research subject,the feasibility of the method is verified by the case study.