Numerical Analysis of Inclined Uplift Capacity of Suction Caisson in Sand

Abstract

Three-dimensional finite element (FE) analyses are conducted to calculate the pullout capacity of suction caisson subjected to oblique loadings. Two sets of FE analyses are performed using Abaqus FE software. In the first set, the sand around the caisson is modeled using the built-in Mohr-Coulomb model (MC) available in Abaqus where constant values of angle of internal friction () and dilation () are defined. The effects of key variables, such as loading angle, mooring position and aspect ratio, on pullout capacity and rotation of the caisson are examined. A comparison between FE and centrifuge test results is also shown. The second set of analyses are performed using a modified Mohr-Coulomb model (MMC) where the pre-peak hardening, post-peak softening and effects of density and confining pressure on stress-strain behavior of dense sand are implemented using a user subroutine by varying  and  as a function of plastic shear strain and confining pressure. Comparing the failure surface development in the soil with increase in loading for two different models (MC and MMC) it is shown that the mobilized  and  varies along the failure planes if the MMC model is used, although the capacity of the caisson could be obtained even if appropriate values of constant  and  are used in the MC model.

Analyses of the Suction Anchor–Sandy Soil Interactions under Slidable Pulling Action Using DEM-FEM Coupling Method: The Interface Friction Effect

“…Both a low interface friction condition (f = 0.35) and a high interface friction condition (f = 0.55) were considered in the simulations. Note that it is a common practice in numerical studies to conduct extension studies using validated parameters, which can save significant amounts of time and resources compared to directly conducting experimental tests [13,25]. However, it is important to emphasize that the most ideal approach is to accompany numerical analysis with corresponding experimental tests whenever sufficient time, test conditions, and funding are available.…”

“…Consequently, assuming a constant load or displacement instead of contact action between hangers and pad eyes (structure-structure interaction) is improper. Although continuous numerical methods including the finite element method (FEM) are capable of simulating the deformation of suction anchors and structure-structure interactions, these methods fall short in terms of accurately simulating large soil deformation and failure (see Figure 1d) [13,14]. Consequently, the discrete element method (DEM) is popular among many researchers, as it can analyze sandy soil behavior on a microscale and model significant soil deformations [15,16].…”

Experimental Work on the Effect of Under-reamed Pile Geometry on the Pullout Capacity of Sand

“…They are a type of deep foundation for different structures, such as offshore platforms, multistory buildings, and transmission towers. Das and Shin [1], Khatri et al [2] explained that belled pile are very promising in terms of tensile load resistance and suited for soil that experiences ground movements as a result of seasonal moisture variation.These piles had been introduced first in India for use in expansive soil, which is classified as problematic soil. Soil layers and pile dimensions greatly affect the load capacity of an underreamed pile.…”