Pullout Capacity of Long Granular Pile Anchors Using Numerical Analyses of Random Fields

The undrained pullout capacity of granular pile anchors (GPA) can be sensitive to changes in soil shear strength. Researchers are intrigued by evaluating spatial variations in soil behavior in geostructures. However, there is a dearth of research on the effect of spatial soil variability on long GPA pullout capacity. The present study conducted probabilistic analyses of GPA pullout capacity using the local average subdivision method (LAS), considering the spatial variation of soil shear strength and its correlation with the soil elastic and shear modulus. The finite-difference method was used to predict GPA behavior in each random field realization to determine the probability of failure using the Monte Carlo method. The results demonstrated that consideration of GPA’s friction angle as a random parameter had negligible effects on pullout capacity. Moreover, the surface heave was limited by increasing the length/diameter ratio to more than 10. The pullout capacity of the GPA decreased by 30% due to a higher horizontal to vertical correlation length exceeding 5. In addition, the safety factor for the empirical equation obtained 1.5 and 2 for coefficient of variation higher and less than 0.2 in an isotropic random field, respectively. Finally, the concrete granular pile anchors were proposed to increase the pullout capacity and reduce corrosion effects on the anchor bar.