The present calculating methods of secondary consolidation of soils do not consider the influence of structure

but most of the natural sediment soils behave the structural characteristics. The tests of marine clay performed by the authors show that secondary consolidation of structural clay relates to load not only in overconsolidation state but also in the process of structure destroying. The secondary consolidation coefficient rapidly increases with consolidation pressure when consolidation pressure is lower than the preconsolidation pressure

and slowly increases when pressure is between the preconsolidation pressure and the structure full yield stress. If the consolidation pressure is higher than the structure full yield stress

the secondary consolidation coefficient would not vary with consolidation pressure. Whether the secondary consolidation coefficient is varied with load should not be judged by preconsolidation pressure

but it should be the structure full yield stress. For marine clay

the varying process of secondary consolidation coefficient can be considered as three phases

i.e. overconsolidation

structure destroy and normal consolidation. A new calculating method is developed

which can reflect the structure behavior of soils.