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基于1∶5的轨道–路基–桩筏复合地基模型,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无砟轨道X形桩–筏复合地基的动力特性模型试验,研究不同激振频率引起的轨道–路基–桩筏复合地基中的速度和动土压力,测得了速度响应、动土压力随深度和激振频率的变化规律。研究结果表明:在路堤横截面方向上,振动响应主要集中在轨道–路基结构中,基床表层中的动土压力在路堤横截面方向呈“W”形分布,地基表面的动土压力呈“U”形分布。基床表层中的动土压力荷载放大系数随激振频率的增加而逐渐增加。相关研究成果可为无砟轨道X形桩–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 1: 5 composite track-subgrade-pile-raft composite foundation, a sinusoidal wave load can be used to simulate the load of a single axle on a train. The X-shaped pile-raft composite foundation with different excitation frequencies Dynamic model test was conducted to study the velocity and earth pressure in the track-subgrade-pile-raft composite foundation caused by different excitation frequencies. The variation of velocity response, earth pressure with depth and excitation frequency were measured. The results show that in the direction of the embankment cross section, the vibration response mainly concentrates in the track-subgrade structure. The earth pressure in the bed surface layer distributes in the direction of the embankment cross section, and the earth moving pressure on the foundation surface shows “U ” shaped distribution. The dynamic earth pressure load amplification factor in the bed surface gradually increases with the increase of the excitation frequency. The relevant research results can provide reference for the theoretical analysis and calculation of X-shaped pile-raft composite foundation and the determination of dynamic load amplification factor.