振动波型对X形桩桩–筏复合地基动力响应影响的模型试验研究

Model tests on effect of vibration waves on dynamic response of XCC pile-raft composite foundation

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 large scale model test system, cast-in-situ XCC pile-raft composite foundation embedded in sand is studied. Under the sine and ＂M＂ wave loads, the change laws of X pile-raft composite foundation are analyzed from aspects of cumulative settlement, dynamic displacement amplitude, dynamic stiffness and vibration velocity. The dynamic response of X pile-raft composite foundation is preliminarily revealed. The test results show that the settlement curve（s-N） of this composite foundation（s is the settlement and N is the load cycle） can be discribed by the logarithmic functions. The dynamic displacement amplitude and dynamic stiffness are related to the form of load and its amplitude. The vibration velocity gradually decreases with the increasing depth. The gravel cushion exerts a good damping effect on the soil in the process of broadcasting velocity to the soil foundation.The research results provide a reference for the use of pile-raft composite foundation.