强震作用下黄土高原地区小半径曲线梁桥地震灾变机理研究

With the implementation of a series of national development plans such as the development of the western region and the construction of new rural, a large number of small radius curved bridges have been built in the Loess Plateau area of northwest China, this kinds of bridge structure is located in the key traffic position such as highway expressway exit ramp, urban overpass ramp and country road. In this project, through the investigation on the seismic damage behavior of curved bridges with small radius in the Loess Plateau region, establishing the nonlinear analysis theoretical model of pile-loess dynamic interaction, and put forward the corresponding nonlinear analysis theory and simulation methods, studying the pile-loess interaction mechanism and the pile foundation failure mode. Through the establishment of pile-loess-structural dynamic analysis model of small radius curved bridge, combine with numerical simulation analysis, designing and carry out tests on dynamic characteristics of small radius curved bridge in the Loess Plateau, studying seismic response law of this kind of bridge structure, extracting the seismic damage mode of curved bridge structures with small radius, and inversion the earthquake disaster mechanism of the curved bridge. The research results can be used to guide the seismic analysis and design of the small radius curved bridge structure, which is a great significance to prevent and mitigate the extensive earthquake disaster of this kind bridge structure in the Loess Plateau under the action of strong earthquake.

随着西部大开发、新农村建设等一系列国家发展规划的实施，在我国西北黄土高原地区建设了数量众多的小半径曲线桥梁，该类桥梁结构多位于高速公路出入匝道、城市立交匝道及通村公路等关键交通部位。本项目通过对黄土高原地区小半径曲线桥梁进行震害调研，建立桩基-黄土非线性动力相互作用理论模型，提出相应非线性分析理论和模拟方法，结合桩基拟静力试验，探究桩基-黄土相互作用机制及桩基失效模式。通过建立小半径曲线桥梁的桩基-黄土-结构动力分析模型，结合数值模拟仿真分析，设计并开展黄土高原地区小半径曲线桥梁结构动力特性测试试验，研究该类桥梁结构的地震响应规律，提炼小半径曲线桥梁结构地震破坏模式，反演给出该类桥梁结构地震灾变机理。研究成果可用于指导黄土高原地区小半径曲线桥梁结构的抗震分析和设计，对防止和减轻强震作用下该类桥梁结构发生大规模地震灾害具有重要意义。

随着我国近年来在黄土高原地区基础交通设施建设的持续深入，曲线梁桥结构以其良好的高差克服、地形适应及构型优美特点，在高速公路匝道、城市立交及机场引道等环境得到广泛应用。小半径曲线梁桥结构的空间构型复杂，水平、竖向结构布置不规则，桩-土作用对该类桥梁结构的动力特性及地震响应规律影响显著，内力及变形耦合程度高，给该类桥梁结构的动力分析及抗震设计带来巨大困难。因而，开展强震作用下黄土高原地区小半径曲线梁桥结构的抗震性能及震灾机制研究具有重要现实意义。.本项目通过建立桩基-黄土动力相互作用模型，提出桩基-黄土作用非线性分析理论，研究了桩基-黄土动力非线性相互作用机理及有效模拟方法，结合有限元模拟分析及室内黄土场地单桩独柱墩的动力特性测试模型试验，深入探讨了桩基-黄土相互作用对结构动力系统振动响应的影响机制；根据桩-土作用理论，严密构建小半径曲线梁桥的黄土-桩基-结构整体动力非线性分析模型，通过对墩高布置、曲率半径、纵坡等进行设计参数分析，探析了各参数对小半径曲线梁桥结构自振频率及低阶振型的影响，总结了强震作用下小半径曲线梁桥结构关键截面的内力及变形响应规律；通过开展黄土场地小半径曲线梁桥结构锤击振动测试模型试验，进一步探究了黄土高原地区考虑桩基-黄土相互作用的小半径曲线梁桥结构动力特性，结合理论分析及数值模拟，反演分析曲线梁桥结构的典型地震灾害模式，揭示了强震作用下黄土场地曲线梁桥结构的致灾机理。.研究成果为揭示桩基-黄土相互作用机制提供重要依据，可用于指导黄土高原地区曲线梁桥结构的动力分析及抗震设计，为修订和完善相关桥梁设计规范提供重要理论支撑，同时也对提高黄土高原地区曲线梁桥结构的耐震抗灾能力具有重要意义。