Experimental Study of Suction Installation of Caissons in Dense Sand

Abstract

Physical models have been developed to investigate suction installation of caisson foundations in fine-grained dense silica sand. The main controlling factor, pumping rate, was found to have significant influence on the differential pressure result across the caisson base. Rapid pumping is unlikely to bring any adverse effect to the installation process, even applied at very shallow initial wall penetration depth. Quick installation, with the exception of caissons with wall-to-diameter (t/D) ratio larger than 1%, appeared to be beneficial in reducing the excessive sand heave. Observations showed that caisson geometry and surcharge also affected the installation performance. Although requiring only marginal increase in suction pressure to install, caissons with thicker walls created substantially higher sand heave during installation. Varying the absolute caisson size did not seem to affect the suction pressure for a given t/D. Seepage flow was also calculated during each test, and found to increase with deeper skirt penetration.