Stability of Suction Foundation against Eccentric Loading

本文通过模型试验和有限元分析，阐明了吸力基础抗倾斜荷载能力的机理。主要研究成果如下：1)吸力基础的水平承载力随内、外径比的减小而增大。当D/B=1.1，竖向承载力=44.1N时，水平承载力比标准地基分别降低约40%和50%。2)水平承载力随着D/B的增大和相对密度的增大而增大。4)当D/B值较小时，地基土体发生滑动破坏。然而，楔体破坏表现为D/B和倾角增大。5)在相同的加载条件下，地基的位移随着D/B的增大和内外径比的减小而增大，并通过模型试验对偏心受力的承载机理进行了评价。主要研究结果如下：(1)竖向承载力随荷载偏心距的增大而减小；(2)承载力随内外径比的增大而减小；(3)吸力基础的抗剪比由基础的尖角决定。(4)桩端阻力在荷载开始时产生。5)在偏心距较小的情况下，与较大的偏心距相比，地基附近呈现出较大的应变场。最后，进行了粘性地基的拉拔试验，以明确吸力的产生机理和破坏模式。

In this study, model test and finite element analysis were performed to clarify the mechanism of bearing capacity of suction foundation against inclined loading. The main findings for the bearing capacity against inclined loading condition are followed ;1)Horizontal bearing capacity of suction foundation increases with decreasing ratio of inner diameter and outer diameter. In case of D/B=1.1 and vertical bearing capacity=44.1N, the horizontal bearing capacity decreases about 40 and 50% compared to a standard foundation.2)Horizontal bearing capacity increases as D/B increases and relative density increases.3)Wedge of strain field is generated around and below a suction foundation. Especially, strain is concentrated adjacent to a foundation.4)Sliding failure is shown in ground under the foundation if D/B is small. However, wedge failure is shown as D/B and inclined angle increase. The pull out failure is shown between sliding failure and wedge failure.5)In same loading condition, displacement of foundation increases with increasing D/B and decreasing ration of inner and outer diameter.In addition, the model test is performed to evaluate the bearing capacity mechanism against eccentric loading. the main findings of suction foundation against eccentric loading are followed ;1) Vertical bearing capacity decreases with increasing eccentric distance of loading.2) Bearing capacity decreases as the ratio of inner and outer diameter increases.3) The shearing ratio of resistance for suction foundation is determined by the sharp of foundation.4) Tip resistance is developed at beginning of loading. After that, suction foundation lactates around the tip of foundation and lateral resistance are gradually developed.5) In the case of small eccentric distance, large strain field are shown adjacent to foundation compared to large eccentric distance.Finally, the pull out test using clayey ground is performed to clarify the mechanism of generating suction and failure mode.