The effect of the gap near the surface in the earthquake response of the structure-pile foundation-ground system

地震作用下，结构-桩基础-地面系统的动力特性已越过桩头附近的差距。因此，本研究以弹塑性理论为基础，建立了考虑“地表与桩头间差距”的地基反力模型。该模型还考虑了循环荷载的影响。通过离心模型试验验证了响应分析的数值结果，并对桩基支撑的临时塔式起重机进行了数值分析和试验研究。两种分析结果吻合良好。同时，桩头附近差距的产生和扩展对起重机振动特性的影响也很明显，说明考虑差距的地基反力模型可以较好地分析结构-桩基-地面系统的地震反应。

The gap near the pile head has been passed over in dynamic behavior of the structure-pile foundation-surface ground system during an earthquake. Therefore, in this study, the subgrade reaction model considering "the gap between surface ground and pile head" was formulated on the elasto-plasticity theory. And that the effect of cyclic loading was also considered in this model. The numerical results of the response analysis were verified by the centrifugal model experiment.A temporary tower crane that was supported on the pile foundation was numerically and experimentally analyzed. Both analytical results agreed well. And also, it became clear that the generation and expansion of the gap near the pile head effected on the vibration characteristics of the tower crane.It is meant that the subgrade reaction model considering the gap is useful to analyze the earthquake response of structure-pile foundation-surface ground system at the good accuracy.