Load - displacement response of the suction anchor in sand

Abstract

Structures installed in the ocean have been increased the size of structures to enhance economy and efficiency. Since the construction on the coast was constrained by the increased size, the construction area was gradually expanded to the deep sea. The foundation systems that are directly connected to the existing structure are vulnerable to lateral moments exerted by the current and service load. Therefore, in deep seas, it has been considered that the concept of floating structures that are not directly connected to anchors is suitable. In order to hold this floating structure, various anchor foundations have been proposed. Having great advantages in installation, utility, and capacity, suction anchors have been considered as one of the optimized anchor foundations for floating structures. The study of suction anchors focused on ultimate bearing capacity. However, in situ condition, the floating structures are under the live load rather than the ultimate state. Thus, a studies about the suction anchor behavior prior to the ultimate state is needed. However, studies on the deformation of suction anchors, in particular, rotational deformation and variations of stiffness have been very limited. Therefore, it is necessary to study anchor behavior according to strain in order to predict the change of capacity due to the rotational deformation or deformation of the anchor before the ultimate state. Therefore, in this study, the main object is the evaluations of the behavior of suction anchors from the initial to the ultimate state. The behavior of anchors includes the pull-out capacity, stiffness change, and deformation (rotation). The comprehensive characteristics of suction anchors in sandy soils were analyzed, and a detailed study was conducted focusing on rotational and rigid deformations for the whole strain level. Finally, the response of the load-displacement curve according to the anchor behavior was analyzed and it is emphasized the necessity to analyze the behavior before the ultimate state in order to understand the suction anchor.