Accounting for Soil Spatial Variability in Plate Anchor Design

The effect of soil spatial variability on the undrained vertical uplift capacity of plate anchors has been examined using the three-dimensional random finite-element approach. Multiple direct Monte Carlo simulations (MCS) were performed to quantify statistically how the anchor uplift capacity varied for variable soil conditions. This allowed examination of the effect of the magnitude of the coefficient of variation (COV) of the undrained soil strength and the spatial correlation scales of these variations on the capacity statistics. Based on the direct MCS results, subset simulations (SS) were then performed to examine how deterministic design approaches would fare in terms of achieved anchor reliability. It was shown that standard approaches could lead to overconservative anchor design, particularly when the scale of fluctuation was small. Finally, a design framework is suggested to achieve the target probability of failure, whereby the characteristic strength profile is selected based on the particular statistics of the site data compared to the anchor size.