Physical model tests of clay-rich submarine landslides and resulting impact forces on offshore foundations

Abstract

Experimental model tests on submarine landslides have been conducted to quantify complete slide events and to determine impact forces on a foundation pillar for clay-rich submarine landslide events on steep slopes. In total, 21 experiments were conducted, where the differences between the experiments were bed inclination and soil properties. All experiments were performed with kaolin clay, where water contents and consolidation time were varied. Each model test was triggered by rapidly increasing the bed inclination of a box containing the slide material. The model tests started as a nearshore slope failure, where the water elevation was aligned with the initial top elevation of the debris material and continued as submarine landslides. The model tests were supplemented with a laboratory testing program, to determine the geotechnical and rheological properties for the soil used in the model tests. The flow mechanism for all experiments indicates a hydro-planning mechanism, with limited contact between the bed and the sliding flow. The results from the model tests have been applied to a field event, based on similitude laws. The normalized results can be applied to estimate the flow envelope for all clay-rich submarine landslides, where undrained conditions apply during the flow event.