Insitu Tests on Consolidation of Composite Foundation Composed of Short Cementsoil Piles and Long Plastic Drainage Plates

Abstract:

Short cementsoil piles and long plastic drainage plates are used to form a new composite foundation,which is called as DM method.It not only improves the bearing capacity of the upper soft soil through the short soilcement piles,but also accelerates the consolidation process of the deep soft soil through the action of long plastic drainage plates.Field tests were carried out to research the consolidation characteristic of this composite foundation at A15 high way in Shanghai,and the test results such as the pore water pressure curves,settlement curves and pilesoil stress ratio curves were analyzed and some conclusions were drawn.The rate of the consolidation of the deep soft clay is greatly accelerated due to the drainage of the prefabricated vertical drain.The DM method improves the bearing capacity of the soft soil;and more than 80% consolidation settlement is finished during the construction period,which effectively reduces the residual settlement.

Key words:composite foundation; DM method; pore water pressure; degree of consolidation; pilesoil stress ratio