Centrifuge tests on axial capacity of suction caissons in clay

摘要

The axial capacity of suction caissons during installation and pullout was investigated for caissons installed either by jacking or by suction. The study was based on centrifuge model tests carried out in both normally consolidated (NC) and lightly overconsolidated (LOC) kaolin clay. The sensitivity of the soil was determined from cyclic T-bar tests and it was found that the fully remoulded shear strength gave good estimates of the shaft friction during caisson installation. The measured installation resistance during suction installation was similar to that during jacked installation in both types of clay. No essential difference was found in the long term uplift capacity of caissons installed by jacking or by suction, according to unsealed pullout tests in the NC clay, and sealed pullout tests in the LOC clay. Lower bound external shaft friction ratios during pullout after consolidation were derived, together with consistent end-bearing factors.