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为了解沿海软土地区PHC管桩在地震作用下的动力反应、桩-土动力相互作用特性以及破坏模式,开展PHC管桩-土-结构模型体系的地震模拟振动台试验研究。通过输入3种不同地震波,并逐渐增加地震波峰值,研究预应力度、土体特性对模型体系的地震响应与破坏模式的影响。研究结果表明:土体饱和与否对模型体系的动力特性和地震响应影响较大,PHC管桩的预应力对其动力特性有一定影响,破坏模式也不相同;土体未饱和时,基本烈度地震作用下PHC管桩的一阶频率下降不大,土体饱和时,随着地震波激励的增加,模型体系的自振频率逐渐下降、阻尼比逐渐增大,PHC管桩-土-结构间的相互作用加大,结构开始损伤破坏,频率最大下降至初始频率的50%;预应力的存在可较显著地减缓地震作用下结构的损伤破坏;加速度峰值越大或者土体越深,孔压比越大,最大超过1.0,并出现液化现象,且液化持续时间远大于地震波持时。研究结果可为沿海软土地区PHC管桩的应用和规范的制定提供参考。
In order to understand the dynamic response, the pile-soil dynamic interaction characteristics and the failure mode of the PHC pipe pile in the coastal soft soil area, the shaking table test of the seismic model of the PHC pile-soil-structure model system was carried out. By inputting three different kinds of seismic waves and increasing the peak values of seismic waves, the influence of prestressing force and soil characteristics on the seismic response and failure mode of the model system is studied. The results show that soil saturated or not has a great influence on the dynamic characteristics and seismic response of the model system. The prestress of PHC pipe pile has some influence on the dynamic characteristics and the failure modes. When the soil is not saturated, the basic intensity Under the action of earthquake, the first-order frequency of PHC pipe pile did not drop much. When the soil saturated, with the increase of seismic excitation, the natural frequency of the model system gradually decreased and the damping ratio increased gradually. When PHC pipe pile-soil-structure Interaction increases, the structure begins to damange and destroy, and the maximum frequency decreases to 50% of the initial frequency. The existence of prestress can significantly reduce the damage of the structure under earthquake; the bigger the acceleration peak or the deeper the soil, Larger, more than 1.0, and the phenomenon of liquefaction, liquefaction and duration is much longer than the seismic wave holding time. The results can provide reference for the application and specification of PHC pipe pile in coastal soft soil area.