Model tests on installation techniques of suction caissons in a soft clay seabed

A series of model tests have been carried out in order to investigate the behavior of suction caissons during installation in a soft clay seabed and explore more effective installation techniques. The test results indicate that when the suction pressure instead of dead weight is adopted to help penetrating the caisson, a greater resistance may be encountered at a large depth. During the process of suction-assisted penetration (SP), all the soil displaced by the caisson wall flows inwards, and even more volume of soil would enter into the caisson before the reverse bearing failure at the caisson tip occurs. This phenomenon would result in a larger soil heave, which makes the final insertion depth of the suction caisson less than the target depth. Although plug failure occurs during the SP process it is possible to install the caisson further, and the inverse bearing capacity failure could be progressive. The test result illustrates that different initial penetration depths by dead weight have little influence on final heights of soil heave inside the caisson. It is beneficial to suppress the development of soil heave by releasing the suction inside the caisson at intervals during the SP process. Adopting a new method of intermittent pumping can effectively reduce the soil heave but not increase the time for caisson installation in a soft clay seabed.