| Abstract: | This is the third in a series of three state‐of‐the‐art papers concerning the geotechnical engineering aspects of the installation of gravity platforms in the North Sea. Andresen et al. (1979) discuss the planning and execution of offshore site investigations and the procedures used to obtain soil engineering parameters. Eide et al. (1979) review the details of the different platform designs and the installation procedures for the thirteen gravity structures that so far have been placed in the North Sea in 70 m to 153 m of water. In this paper, the foundation engineering for gravity structures installed in the North Sea is reviewed including recommended analyses of permanent and cyclic foundation deformations, dynamic behavior, foundation stability, skirt penetration resistance and base contact stresses, potential piping and erosion problems, and stresses in oil wells and risers. Field performance observations are reported, and it is concluded that gravity structures may safely be installed in offshore areas with less favorable platform foundation conditions than so far encountered in the North Sea. |
