Helical Anchor Pullout Capacity in Sand Overlain by Clay: Experimental and Numerical Insights-PPT Presentation

PPT Presentation

Pdf Summary

The presentation investigates the pullout capacity of circular plate anchors embedded in sand overlain by clay, motivated by reclaimed ground conditions at Kooragang Island, Newcastle. There, dredged sand fill overlies soft clay and then medium-dense to dense sand, while research on anchors in layered soils remains limited. Anchor capacity and failure can depend on interactions between the anchor and soil layers, with shallow, deep, and transitional failure mechanisms possible.<br /><br />The experimental program used two small-scale test setups: a cylindrical PVC chamber and a rectangular chamber with a Perspex face. Anchors of different sizes were loaded using a triaxial testing machine. Variables included anchor diameter, embedment depth, clay undrained shear strength, pullout rate, and saturation; sand and clay types were controlled.<br /><br />The numerical study used limit analysis software (Optum CE) to calculate lower- and upper-bound capacities. Its methodology was benchmarked against published results, with bounds agreeing to within approximately 5%, and the experimental cases were also simulated. Comparisons included uniform sand and layered clay-over-sand conditions, as well as dry and saturated experimental tests.<br /><br />The presentation outlines the study’s approach and comparisons but does not state detailed quantitative conclusions about how individual variables affect capacity. Future work includes developing an analytical model, further numerical investigations, additional experiments on loading rate, installation and cyclic effects, field-scale testing, and design charts or other tools.

Keywords

circular plate anchors

pullout capacity

layered soil

sand over clay

reclaimed ground

Kooragang Island

experimental testing

limit analysis

embedment depth

undrained shear strength