The Study On Sea Bed Stability From Waves In Huanghe River Delta

When the water waves propagate over a porous sea bed, they will create effective stresses and pore water pressure,which will take dangers to offshore structures such as oil flats and submarine pipes. So it is very important to spend a lot of time and energies on doing research for seabed stability form waves.The dissertation is mainly divided into three parts. The first part of the dissertation is laboratory experiment about the silty soils liquefaction from cyclic loads. Here the devices was designed by author himself and the cyclic air pressure was used to simulate waves. During the experiment, the pore water pressure was measured by the pore water pressure collection system. At the meantime, some phenomena such as soil volcano and fluidization were observed. After the cyclic loads, subminiature static cone penetration was taken to measure the field strength of silty soils and other index of physics and mechanics was obtained by geotechnical tests. On the basis of laboratory experiment, some conclusions were drawn. These conclusions are:The content of cohesion play a important role in the liquefaction of silty soil, which make it difference from sand soil. Before the silty soils liquefied, they must override the effect of structure mechanics linked to cohesion.On the action of cyclic loading, hard layer was formed in the depth of 35cm from the surface of soils.The soil volcano and fluidization are main style of the dissipation excess pore water pressure in the soils.The second part of the dissertation is mainly about wave induced sea bed shear failure. Biot's theory with finite element solution was used to analyse the sea bed response from the waves. In order to verify the accuracy of solution of the control equation, the calculated results was compared with yamamoto's result by using the same parameters. From the compare, the two results are compatible. Then the wave...