液化侧向扩展场地中排水刚性桩-土动力相互作用机理研究

With the nationwide rapid development of bridge construction, the pile foundation of bridge is prone to failure caused by seismic liquefaction-induced lateral spreading. The rigidity-drain pile is a new type of anti-liquefaction foundation reinforcement method, which has the advantages of low construction cost and quick construction speed, but its theoretical research is obviously behind the practice. This study aims to reveal the dynamic interaction mechanism of rigidity-drain pile-soil system by experimental research, theoretical analysis and numerical simulation methods. The shake table test of rigidity-drain pile in liquefaction-induced lateral spreading site is carried out to reveal the response law of soil pore pressure，pile side friction and et.al under seismic load and their relation with the drainage parameters. The effect of pile-soil-pile interaction on the liquefaction resistance of the pile group and the influence of the design variables of the pile group on its influence range are study.The relationship between dynamic parameters of soil and drainage parameters is studied by dynamic triaxial test.A large-scale parallel dynamic calculation method for pile-soil system based on OpenSees program is established. The proper constitutive model of pile-drainage body- soil interface of dynamic analysis is developed. The p-y curve of the pile-soil dynamic interaction of the liquefied lateral site considering the pore pressure accumulation process is established. The research results will enrich the basic theory of soil dynamics and provide a scientific basis for the mechanism of pile-soil interaction and provide a theoretical background for the application of rigidity-drain pile.

我国桥梁建设飞速发展且多采用桩基，建桥区由于地震液化触发场地侧向扩展，极易造成桩基破坏。排水刚性桩作为一种新型的抗液化加固措施，具有工程造价低，施工快捷等优点，但其理论研究明显落后于实践。本项目拟采用试验研究、理论分析和数值模拟等手段，对地震作用下液化侧向扩展场地中排水刚性桩-土动力相互作用机理展开研究。开展液化侧向扩展场地排水刚性桩的振动台试验，揭示超静孔隙水压力分布、桩侧摩阻力等变化规律与排水参量的关系;研究排水刚性桩桩群的桩-土-桩相互作用机理，揭示桩群设计变量对动力响应的影响。通过动三轴试验研究土层动力参数与排水参量的关系。建立“桩-排水体-土”界面动力本构模型，基于OpenSees程序研究桩群-土系统的大规模并行动力计算方法。建立考虑孔压累计过程的排水刚性桩-土动力相互作用p-y曲线。研究成果将丰富土动力学在此领域的基础理论，并为排水刚性桩的应用提供科学依据。

采用试验研究、理论分析和数值模拟等手段，对地震作用下液化侧向扩展场地中排水刚性桩-土动力相互作用机理展开研究。主要成果包括：构建了可液化倾斜场地中排水刚性桩振动台试验系统，开展了可液化倾斜场地中排水刚性桩振动台试验；从土体内部动孔压响应、液化土体的流动性质、桩顶水平震荡位移等研究了排水刚性桩对可液化倾斜场地的处理效果。建立了“桩-排水体-土”界面动力本构模型，研究了桩群-土系统的大规模并行动力计算方法。建立考虑孔压累计过程的排水刚性桩-土动力相互作用p-y曲线。开展了液化侧向扩展场地中排水刚性桩-土动力相互作用的振动台试验研究。研究了排水刚性桩群桩的布桩方式、地基相对密实度等因素对于地基超孔压比、岸壁水平位移、地基沉降、桩顶水平位移等地基和桩的地震响应。开展了液化侧向扩展场地排水刚性桩群桩体系的振动台实验，验证了其抗液化效果。同时研究了桩间距、地基相对密实度和岸壁边桩距等因素对加固效果的影响和对群桩基础动力特性的影响。通过振动台试验，研究了排水桩刚性桩-上部结构-挡墙体系在液化侧向扩展场地中的动力响应。揭示了不同因素对抗液化效果和对液化侧向流动的限制影响，以及对上部结构的稳定性的提升。开展了新型刚性排水管桩处理液化扩展场地的振动台试验。研究了地基的相对密实度、坡肩距、地震波特性、加速度峰值等因素对地基沉降、岸壁扩展、承台位移、地基超孔压比、桩身弯矩等动力响应的影响。验证了新型刚性排水的管桩的抗震性能和处理液化扩展场地的效果。开展了液化倾斜场地中排水板桩结构加固桥梁基础的振动台试验。分析了对桥梁桩基的破坏作用的减轻效果，阐明远/近场地震动作用的影响。开展了新型排水PCC桩加固珊瑚砂路基-路堤-海堤模型的振动台试验研究，揭示其抗液化性能。研究成果对于液化侧向扩展场地中桩基础的抗震设计提供支撑，并为排水刚性桩的应用提供科学依据。