The Study on the Restoration of Forgotten New Type Ocean Foundation "Suction Foundation"

本文的研究总结如下：(1)对相关文献和参考文献的研究。在世界上现有的10个吸式沉箱基础中，大多数是安装在北海的石油开采项目中。包括在日本的三个装置，对吸式沉箱基础的应用现状进行了调查和了解。(2)海底吸力沉箱基础加载的理论解释与验证吸力沉箱基础是利用其向上的茶杯形沉箱抽出海水时在其体内外产生的压差（这种负压称为“吸力”）安装在海床上的。本研究从理论上阐述并验证了一种确定吸排量（泵容量）的方法。(3)加载后的支撑力和位移结构的澄清。虽然与数值沉箱有一些相似之处，但吸力基础没有底部。相反，沉箱内部渗透的土壤充当了这个基础的底部。因此，可以认为吸力沉箱内部土体的变形对该基础的支护能力和位移有影响。开底沉箱基础的承载力计算公式尚未建立。本研究试图通过模型试验、有限元分析和逻辑观察来澄清这些问题。

The summary of this study is as follows :(1) Research on related literature and other referencesIn 10 existing suction caisson foundations in the world, the majority of them are found installed for oil excavation projects at the North Sea. Including three installations in Japan the current applications of suction caisson foundation are investigated and understood.(2) Theological explication and validation in loading suction caisson foundation on seabedSuction foundation is installed on seabed by using the pressure difference (this negative pressure is called 'suction') created inside and outside of its body when pumping out the seawater from its upturned tea cup-shaped caisson. In this study, a method to decide the amount of suction and drainage (capacity of the pump) is theologically explicated and verified.(3) Clarification of the support power after loading and displacement structureAlthough sharing some similarity with the numeric caisson, suction foundation doesn't have the bottom part. Instead, the soil penetrated inside of the caisson acts as a bottom for this foundation.Therefore, it can be assumed that the deformation of soil in the inside of suction caisson_has the influence on support power and displacement in this foundation. The formula of support power for open bottom caisson foundation has not been established.This study attempted to clarify these problems by model tests, finite element analysis, and logical observations.