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基于大比例模型试验,采用能够近似模拟列车单个轮轴荷载的正弦波荷载,在砂土地基中通过开展不同激振频率下X形桩桩-筏复合地基的动力特性模型试验,研究激振频率对X形桩-筏复合地基动力响应的影响。着重分析了不同激振频率引起的X形桩-筏复合地基的速度、动土压力、桩身动应力等,获得了速度响应、桩身动应力随深度的变化规律。结果发现:筏板的速度响应幅值随着激振频率的增加近似呈线性增加;地基表面动土压力和动力荷载放大系数随激振频率的增大而增大,且增幅逐渐加大;桩顶动应力随激振频率的增大而逐渐增大。相关研究成果可为我国高速铁路桩-筏复合地基的理论分析与计算以及动力荷载放大系数的确定提供参考依据。
Based on large-scale model tests, using a sine wave load that can approximate the train’s single axle load, a dynamic model test of the X-piles pile-raft composite foundation under different excitation frequencies is performed in a sandy soil foundation to study the excitation frequency. Influence of dynamic response of X - pile - raft composite foundation . The velocity, dynamic earth pressure, and dynamic stress of the pile were analyzed with the help of different excitation frequencies, and the law of velocity response and dynamic stress of the pile with depth was obtained. The results show that the velocity response amplitude of the raft increases approximately linearly with the increase of the excitation frequency; the dynamic soil pressure and the dynamic load amplification factor of the ground surface increase with the increase of the excitation frequency, and the amplitude increases gradually; The dynamic stress gradually increases with the increase of the excitation frequency. The relevant research results can provide reference for the theoretical analysis and calculation of the pile-turnout composite foundation of high-speed railway in China and the determination of the dynamic load amplification factor.