Predicting the overall horizontal bearing capacity of jack-up rigs using deck–foundation–soil-coupled model

Abstract

The overall bearing capacity of a jack-up rig under horizontal load is conducted using finite element models that consider the deck–foundation–soil interaction. In these models, the simplified horizontal load acts on the deck and increases until the platform loses its stability. The effects of the self-weight of the platform W and load direction α on the ultimate horizontal bearing capacity Hult are investigated, and W- Hult failure envelopes under different α conditions are obtained. Two typical seabed types, including the double-layer seabed of sand overlying soft clay and the single-layer seabed of sand, are considered. The results show that a critical self-weight Wcritical exists in the double-layer seabed. Based on Wcritical, the failure of the platform presents two different modes. When W <  Wcritical, the windward leg is pulled up, and Hult increases with the increase in W. When W >  Wcritical, the failure mode is the leeward leg or legs puncturing the bearing sand layer, and Hult decreases with the increase in W. In the single-layer seabed, the failure mode is the windward leg being pulled up, and Hult increases with the increase in W throughout the whole range. The W- Hult envelopes in these two types of seabeds are basically the same when W <  Wcritical.