Centrifuge Tests on the Lateral Behavior of Offshore Monopile in Saturated Dense Sand under Cyclic Loading

In this study, the cyclic lateral behaviors of an offshore monopile in saturated dense sand under cyclic loading was investigated using centrifuge model tests. The soil used for testing was Jumunjin sand, which was deposited with a relative density of 80 %. A static loading test was carried out to obtain the static lateral capacity of the monopile, from which the magnitudes of cyclic load were determined at 30 %, 50 %, 80 %, and 120 % of the lateral capacity. A hundred cycles were applied to the pile head with the frequency of 0.125 Hz. Experimental cyclic p-y curves were obtained at 2, 5, and 7-m depths, from which equations for cyclic p-y curves for saturated dense sand were proposed. The proposed p-y curve was compared with the conventional p-y curves; it was found that the proposed equations overestimate the ultimate soil resistance compared with the conventional ones, whereas the initial modulus of subgrade reaction was only 35 % the conventional ones.