Load transfer model for piles in calcareous soil

The design of pile foundations to support offshore oil and gas production platforms has generally focused on the peak load that the piles must withstand, treating that load as a single (static) event. However, in calcareous deposits, more attention must be paid to the cyclic nature of loading on offshore platforms. Laboratory and field tests have shown that the axial pile response deteriorates under cyclic loading at load levels well below the static capacity. A model of the load transfer response along the shaft of piles installed in calcareous deposits, with particular emphasis on modelling the degradation under cyclic loading, has been implemented in a computer code, RATZ. The model has been used to match experimental data and to assess the likely response of prototype piles. The paper outlines the principal features of the load transfer model, and discusses the main assumptions incorporated in the model. Comparisons with experimental data are presented and a typical prototype situation is analysed and used to provide guidelines for the design of piles in calcareous soil (A).