Response of Silts to Wave Loads: Experimental Study

The response of a nonplastic silt subjected to water waves was investigated in a laboratory wave tank facility. The deposit was created by slurrying the silt into a sediment bay, and pore-water pressure transducers were placed at various depths within the deposit to measure the dynamic response under wave loading.

Tests were run under varying hydrodynamic conditions. At higher wave heights, the pore-water pressures rose continuously and resulted in liquefaction of the silt. Intermediate wave heights caused observable deformations, while low wave heights generated positive pore-water pressures that appeared to reach steady state nonfailure conditions in a few minutes.

The results from the testing suggest that normally consolidated silty marine sediments at low overburden stresses can liquefy at substantially lower cyclic stress ratios than currently available data for sands would indicate. This observation suggests further that utilization of data for sands could lead to unrealistic design practices in offshore regions of silty material.