Field Trial and Numerical Back-Analysis of Suction Caisson Extraction in Hong Kong

An in-situ push-out test was carried out on a 3.4m diameter, 12m high trial suction caisson to determine the ultimate uplift capacity and, in particular, the shaft friction that could be generated along the walls of the caisson. The test was performed in the south-eastern waters of Hong Kong in ground conditions comprising soft clay with alluvial sand at the caisson tip. Numerical back-analysis of test reveal that considerable suction was generated at the caisson base due to a combination of the relatively high rate of loading adopted in the test and the silty nature of the alluvium. Inferred friction values generated on the outside wall of the caisson are found to be in line with existing data reported in the literature.