Resistances of Caisson on Expanded End Pile Foundation to Waves and Earthquakes

采用基于有效应力模型的液化分析方法，对1995年兵库县南部地震中扩端桩基础上的沉箱的动力特性进行了数值分析。通过数值算例，研究了填海造地液化对策对沉箱结构动力特性的影响。从地震作用下变形控制的角度，探讨了复垦地采用不液化材料和轻质材料的可行性。进一步考虑了沉箱结构与桩基连接条件的差异。沉箱结构后填海造地采用不液化材料和轻质材料对沉箱结构的最终残余变形有显著影响。上述地震响应分析需要基本特性，如摩擦力和吸力，这些特性规定了沉箱或桩与其接触土壤之间的相互作用。然后，在东京湾和舞鹤湾的软泥海床上对重力式混凝土块和吸力桩的抗拔力进行了现场测量。为了弄清吸力对沉箱底部和扩底桩的影响，必须对混凝土块和吸力桩的抗拔力进行检测。提出了摩擦力和吸力的估算方法。利用这些估计值进行地震响应分析。

Dynamic behavior of a caisson resting on the expanded end pile foundation against the 1995 Hyogo-ken Nanbu Earthquake was numerically evaluated by a liquefaction analysis based on an effective stress model. The effect of liquefaction countermeasures in the reclaimed land on the dynamic behavior of the caisson structure was investigated using some numerical example. The feasibility of using non-liquefied material and light-weighted material in the reclaimed land was investigated from the viewpoint of deformation control during the earthquake motion. Further the difference in the connection condition between the caisson structure and the pile foundation were considered. The application of non-liquefied material and light-weighted material to the reclaimed land behind the caisson structure has a significant effect on the final residual deformation of caisson structures. The seismic response analysis described above required the fundamental properties such as the friction and the suction those specify the interaction between the caisson or piles and the soils contact with them. Then, field measurements on the pullout capacity of a gravity-type concrete block and a suction pile were conducted on the soft mud seabed located Tokyo and Maizuru Bays. It is important to examine the pullout capacity of the concrete block and suction file in order to clarify the effect of suction acting on the bottom of the caisson and the piles with expanded end. The estimate procedure for the friction and the suction was proposed. Using these estimations the seismic response analysis are processing.