Cyclic Behaviour of a Malaysian Deepwater Clay

Offshore structures are subjected to cyclic loading from a range of sources and an appreciation for how the underlying soil responds to that loading is essential for design. The behaviour of soil under cyclic loading differs to that from monotonic loading and advanced laboratory testing is required to assess this behaviour. This paper describes the behaviour of a deepwater soft clay under cyclic loading. The site is located offshore Sabah, Malaysia in water depths up to 1,200 m. As part of the geotechnical investigation for the site, a suite of cyclic simple shear tests was carried out on samples retrieved from boreholes on the site. Results from this suite of tests were used to establish a set of cyclic contour diagrams for the site. These contour diagrams will be used in the design of foundations for offshore structures at the site. This is the first comprehensive study of the cyclic behaviour of deepwater Malaysian clay. As such, they provide a useful starting point for the development of contour diagrams in similar soils.