LIQUEFACTION AND EROSION OF CHINA CLAY DUE TO WAVES AND CURRENT

P.J. de Wit, C. Kranenburg

Abstract


A research project was started to study the behaviour of cohesive sediments at the Delft University of Technology in 1989. An existing flume was modified to study the liquefaction and erosion of China Clay due to waves and current. China Clay is an artificial mud, mainly consisting of kaolinite. Among other things, the experimental results showed that fluid mud was generated by wave action if the wave height exceeded a threshold value; the threshold value increases as the consolidation period increases. Waves were significantly damped when a fluid mud layer was present and the damping was only little influenced by a current. Furthermore, the fluid mud is transported very easily by a current and hardly any mud was entrained into the water layer during this process. The pore pressure showed a transient decrease when the mud started to liquefy, succeeded by a gradual build-up of an excess pore pressure to compensate for the vanishing effective stress. Finally, it was found that observations or measurements made at a sidewall during an experiment only give a rough indication of the physical processes away from the sidewall; measurements carried out far from a wall have to be used for a quantitative description of the bulk processes in the bed.

Keywords


liquefaction; erosion; China Clay

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