Stability analysis of clayey sloping seabed under extreme wave loads
NIAN Tingkai;LIU Min;LIU Bo;ZHENG Defeng;SONG Lei;YIN Ping;State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology;School of Urban and Environmental Science,Liaoning Normal University;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology;Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology,Ministry of Land and Resources;
The shear strength of soft clay in sloping seabed will be weakened due to the structure failure induced by marine resource exploration. Under extreme wave loads once a hundred years,local slide or even large-scale landslide will happen in the seabed. This will influence greatly the construction and normal operation of ocean engineering. Currently,the limit equilibrium method( LEM) has been one of the most popular approaches to assess the whole or local stability of clayey sloping seabed. But the method has some limitations and only the approximate solutions can be obtained. Based on the upper bound approach of limit analysis,the paper derives the external work rates produced by the wave-induced pressure on the sloping seabed. The limit state equation of sloping seabed under wave loading is established through the external work rates being equal to the internal energy dissipation rates along the log-spiral sliding surface. The factors of safety( FS) at the different time under one-wave period are obtained by using the optimization method combined with numerical integration and strength reduction technique. A representative example is employed,and the analytical solutions of stability for the disturbed sloping seabed under wave loading are verified by comparison of the finite element results. On this basis,the stability of clayey sloping seabed under extreme conditions such as various wave parameters( i. e.,wave length,wave height and water depth) and the special case of slope length no more than one wave length are discussed in detail.