Development of a combined VHM loading apparatus for a geotechnical drum centrifuge

Foundations, especially those for offshore structures, are often subjected to combined vertical (V), horizontal (H) and moment (M) loading conditions. Experimental studies of foundation behaviour under complex combined loading are normally limited to laboratory testing at unit gravity. Only a few studies have been performed at enhanced gravities in a geotechnical centrifuge owing to difficulties in the design of actuators with independent control of movements in three degrees-of-freedom. In this paper, a combined VHMloading apparatus,with independent control of the in-plane vertical, horizontal and rotational movements is reported. Test results that measure the size and shape of the combined VHM yield surface of a spudcan footing of a mobile jack-up platformin soft clay illustrate the capabilities of the newapparatus.