Analysis of foundation stability of marine retaining bunds, during construction stages, using effective stress

Staged construction uses controlled rates of loading to enable soil strengthening via consolidation, in order to increase the foundation stability. The use of total stress analysis assuming instantaneous loading can sometimes lead to excessive conservatism as it makes no allowance for an effective strength gain that will occur during staged construction.

Experimental determination of consolidation parameters CV and A can allow an estimate to be made of the excess pore water pressure dissipation for any given length of time. The designer can then calculate the stability of the foundations at any given stage of construction using an appropriate effective stress stability analysis method.

Using effective stress analysis allows for an efficient design solution in which load timing can be manipulated to maintain adequate foundation stability. With an effective stress method design assumptions can be verified using piezometers to monitor the excess pore water pressures during construction.

Studies of three marine reclamation bund failures have verified that the effective stress method of analysis does give reasonable predictions of the actual factor of safety.