The effect of spatial variability in undrained shear strength on the ultimate capacity of plate anchors

The paper presents the results of a numerical study carried out to analyse the impact that spatial variability in undrained shear strength has on the uniaxial undrained capacity of a deeply embedded plate anchor. Vertical (uplift) load, horizontal load and overturning moment are examined. The Random Field Finite Element Method (RFEM) was adopted in the study, with undrained shear strength prescribed using a random field within a small strain finite element analysis. The numerical results show that the ultimate capacity of the anchor is a function of the spatial variability, and that the capacity factors under pure vertical, horizontal and moment loading can be expressed either as a probability density function, or reduced to a constant value, when normalising by an ‘operative’ shear strength, which accounts for the variability.