考虑土体液化侧扩流影响的桥梁桩基屈曲失稳判别方法研究

Soil liquefaction has caused buckling instability to bridge pile foundation in past earthquakes, and the seismic design code for buckling instability of pile in liquefiable soils is still in shortage. This project takes the rock-socketed pile which is subjected to liquefaction-induced lateral spreading as the research object. Model tests, theoretical analysis, numerical simulation, and earthquake damage surveys will be adopted to study the seismic behavior of pile under the combination action of lateral and axial load. This project mainly concerns the effect of lateral spreading on the buckling instability of pile and proposes a calculation model for the buckling stability analysis of pile. Moreover, parameter studies will be performed to identify the key parameter affecting the pile buckling behavior. Finally, a discriminant method for buckling instability of pile subjected to liquefaction-induced lateral spreading is proposed for engineering design. The study would greatly help improve the understanding of buckling failure mechanism and accurately predict the buckling instability for bridge pile foundation under strong earthquakes. It also aims to enhance the seismic design code for the pile, which is significant in engineering practice as well as in theory research.

基于土体液化造成桥梁桩基屈曲失稳的震害事实，针对液化侧扩流场地桩基屈曲失稳防控设计规范缺失的问题，本项目以倾斜液化场地嵌岩桩为研究对象，采用试验方法、理论分析、数值模拟与震害调查相结合的研究手段，探究侧向荷载（土体液化流动土压力和上部结构惯性荷载）和轴向荷载耦合作用下桩基地震反应规律，突出液化流动土压力对桩基屈曲失稳的影响效应，致力于桩基屈曲失稳的有效防控，聚焦提出桩基屈曲稳定分析计算模型，精准识别桩基屈曲失稳主控因素，力求构建便于工程应用的液化侧扩流场地桥梁桩基屈曲失稳判别方法。这对于客观认识桥梁桩基地震反应规律与屈曲失稳机理，精准分析桥梁桩基稳定性，科学完善现行液化侧扩流场地桥梁桩基抗震设计规范，有效实施桥梁桩基抗震设计等，具有重要理论和现实意义。

项目以桥梁工程中嵌岩桩为研究对象，采用试验方法、理论分析、数值模拟与震害调查相结合的研究手段，从液化侧扩流场地桩基屈曲失稳物理机制、桩基屈曲失稳分析方法、桩基屈曲失稳判别方法和基于废弃矿渣粉的加固方法4个方面开展研究。取得如下重要成果：①证明了土体液化条件下桩的屈曲失稳是由侧向荷载和轴向荷载共同作用引起的，惯性荷载会降低桩的屈曲临界荷载，而土体液化后的残余强度的会增大桩的屈曲临界荷载。②获得了一套完整的液化侧扩流场地桩基屈曲稳定分析计算模型构建方法，包括数值建模途径、关键技术问题处理方法、计算软件程序开发等。③提出了易于工程应用推广的液化侧扩流场地桩基屈曲失稳判别方法。④发现了矿渣粉和碱激发矿渣胶凝材料是可靠的抗液化加固材料，能有效增强土体的抗液化能力，减少地震下液化场地桩的侧向变形，进而避免桩的屈曲失稳。项目研究成果对于客观认识液化场地桩基地震反应规律与失效机理，精准分析桩基竖向承载力，科学完善现行液化场地桩基抗震设计规范，有效实施桩的抗震设计等，具有重要的理论和现实意义。.项目执行过程中，发表学术论文13篇，其中SCI收录论文11篇（JCR1区7篇，JCR2区3篇），EI收录论文1篇，国际会议论文1篇；授权发明专利2项，申请发明专利3项；授权实用新型专利1项；授权计算机软件著作权2项；参加学术会议9次，做分会场报告4次；培养岩土工程方向硕士研究生6名。