Drained Uplift Capacity of Drilled Shafts under Repeated Axial Loading

Abstract

An experimental study of the effects of repeated axial loading on drained uplift capacity of drilled shafts in granular soil is described. The mechanisms that cause changes in drilled shaft side resistance are identified and the effects of initial soil density, shaft‐depth‐to‐diameter ratio, and magnitude of repeated loading are evaluated. Uplift capacity changes are found to depend primarily upon the magnitude of cyclic displacement, and a relationship between the magnitude of cyclic displacement and uplift‐capacity reduction is presented. Critical levels of repeated loading (CLRL) are established, above which shafts fail in uplift and below which failure under repeated loading does not occur. Implications for the design of drilled shafts under repeated axial loading are presented.