Ashraf, Adnan (2018-07). Lateral Capacity of Suction Caissons in Bilinear Soil System. Master's Thesis. Thesis uri icon

abstract

  • Suction caisson anchors have been proven as efficient and cost-effective foundations for offshore wind turbines. These anchors are subjected to lateral loads which are typical of offshore environment. Many efforts have been made to determine the ultimate lateral capacity of the soil around caissons. Upper bound plastic limit analysis provides a useful framework to estimate the lateral capacity under undrained conditions. A three-dimensional collapse mechanism is assumed by defining four optimization parameters along the geometry of the failure, and ultimate capacity is determined by optimizing the parameters. This method is able to incorporate the soil complexities and has been successfully used in industry for years. But the drawback of the approach is that it requires a lot of computational effort due to the optimization parameters involved. A computationally more efficient method has been devised by reducing the optimization parameters from four to one. However, the expedient restricts the method to analysis of caissons in uniform or linearly varying undrained strengths. In reality, offshore soils are different from strength profile of uniform or linearly varying strength. This research is aimed to develop a methodology which could make the simplified method applicable for bilinear soil strength system. An equivalent strength profile is proposed which, in turn, is used in the simplified method for the estimation of ultimate capacity. The results are validated by the upper bound plastic limit analysis. In the end, series of parametric studies are performed to affirm the validation of the proposed methodology.

publication date

  • July 2018