Numerical limit analyses on the uplift capacity of strip plate anchor in anisotropic spatially random cohesive soil

Abstract

Plate anchors are used to resist uplift forces of both offshore and on-land structures. Numerous studies have been carried out to date to evaluate the ultimate uplift capacity of anchor plates. Most of them assumed the soil as homogeneous and isotropic. Naturally, the soil is heterogeneous and anisotropic. The undrained shear strength of soil may vary significantly within a seemingly homogeneous layer. This paper analyzes the impact of spatial shear strength variability of cohesive soil on the uplift capacity of strip anchors through numerical limit analyses. Repeated Monte Carlo simulations within a selected range of both isotropic and anisotropic spatial correlation length and coefficient of variation of undrained shear strength are conducted using the random field theory to evaluate the effect of probabilistic uplift capacity of shallow and deep strip anchors. The outcomes are then compared to those of a similar study in which the probabilistic uplift capacity was investigated using a displacement-based analysis employing the local averaging subdivision of the random finite element method (LAS-RFEM). The comparison depicts the requirement of a higher safety factor than the published results of RFEM. The findings suggest considering the spatial variation of soil strength for the safe design of plate anchors.