Suction contribution to uplift capacity of suction buckets under serviceability conditions

Abstract

Suction pressures induced inside buckets under tensile loads can greatly increase bucket uplift resistance. However, a considerable bucket upward displacement is required to mobilize a sizeable part of the suction pressure, which may not meet the serviceability requirements. To address this issue, this study emphasizes that suction buckets operate under compressive preloading conditions owing to their self-weight and potential ballasting, and that reduced compressive preloading can result in suction pressures at the underside of the bucket lid. The critical suction pressure, which refers to the suction pressure under the lid bottom at the instant at which the lid separates from the soil surface owing to tension, was identified and considered to contribute to the bucket uplift capacity. An axisymmetric consolidation model was developed to quantify the critical suction pressure. Analytical solutions were obtained using integral transformation techniques and verified using published data. A detailed parametric study was then conducted to explore the effects of bucket and soil parameters on the critical suction pressure. The results indicated that the critical suction pressure was robust despite significant variations in the soil permeability and boundary drainage conditions. This study provides new insights into the serviceability-driven design of suction buckets subjected to tensile loads.