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基于大比例模型试验系统,开展砂土地基中现浇X形桩桩–筏复合地基的模型试验研究;分析正弦波与“M”波荷载作用下X形桩桩–筏复合地基的累计沉降、动位移幅值、动刚度、振动速度等的变化规律,初步揭示X形桩桩–筏复合地基动力响应机理。试验结果表明,桩筏复合地基的沉降s与荷载循环次数N的关系曲线可近似用对数函数描述;动位移幅值和动刚度与荷载形式和振幅有关。振动速度随深度增加而逐渐衰减,碎石垫层在振动速度向地基土传播过程中起到了良好的减震作用。研究成果为X形桩–筏复合地基的应用提供了参考依据。
Based on the large-scale model test system, the model test of cast-in-situ X-shaped pile-raft composite foundation in sandy soil is carried out. The cumulative total of X-shaped pile-raft composite foundation with sine wave and “M” Settlement, the dynamic displacement amplitude, dynamic stiffness, vibration velocity and other changes, revealing the dynamic response of X-shaped pile-raft composite foundation. The experimental results show that the relationship between the settlement s of the raft composite foundation and the number of load cycles N can be approximated by a logarithmic function. The magnitude of dynamic displacement and the dynamic stiffness are related to the load form and amplitude. Vibration velocity gradually decreases with the increase of depth, and the gravel cushion plays a good role in shock absorption when the vibration velocity spreads to the foundation soil. The research results provide a reference for the application of X-shaped pile-raft composite foundation.