GEOTECHNICAL ASPECTS OF SUBSIDENCE RELATED TO THE FOUNDATION DESIGN OF EKOFISK PLATFORMS

This paper reviews the effects of up to 20 m of subsidence occurring i n the central Ekofisk field upon the design of foundations for the ste el piled jackets placed in the field, close to the centre of the subsi dence bowl, The first part of the paper compares the results of a fini te element analysis of the earth's crust with measurements of subsiden ce and of horizontal movements at the centre of the Ekofisk complex, T he second part of the paper assesses the progressive effects of the su bsidence on the in situ behaviour of the sea-bed soils, and provides e stimates of the changes in soil strength parameters which are expected to occur due to the subsidence, The final part of the paper examines the long-term effects of the soil stresses and strains, including the anticipated changes in soil behaviour, on the design and predicted per formance of the new jackets and piled foundations.