Model tests on penetration of suction anchors in medium-coarse sand

Suction anchors are widely used in offshore engineering for fixing platforms, offshore wind turbines and mooring floating facilities. Penetration of suction anchors, i.e., driven into a desired position in the seabed by the suction, is a key factor for the design. It is necessary for the bearing capacity to meet the needs. Researchers have focused their attention on the installation in the fine sand in a medium or dense state, silt and clay. This study shows that it is feasible for the penetration of suction anchors in the natural medium-coarse sand. Model tests are carried out to investigate the behavior of the penetration of steel suction anchors in medium-coarse sand by varying water levels and pumping speeds. The relation between the suction and the penetration depth is obtained. By comparing different installation approaches, the optimized method to achieve the maximum penetration depth is put forward. The formation of water/soil plug is observed by using Perspex suction anchors, and reasons for preventing the penetration of suction anchors are analyzed. Compared with the jacking tests, the seepage induced by vacuum plays a vital role in assisting the suction anchors to achieve the penetration in the medium-coarse sand. Finally, an approach is developed to calculate the required suction under a desired penetration depth on the basis of the model tests.