DESIGN OF DRAINS AND SURCHARGE IN RECLAMATIONS.

Abstract

Thick marine clay deposits underlying reclamations have often been treated with vertical drains and surcharge to reduce excessive differential settlements before construction of roads, runways and other structures. Biot's theory of consolidation is implemented, using a 2D plane strain finite difference scheme, in the solution of the field consolidation problems. To simulate the effect of vertical drains, the soil with drains installed was approximated to a soil with an equivalent increased vertical permeability in a rational manner. The numerical scheme was used to demonstrate the back pressure effect caused by the inflow and backup of excess pore pressure from the untreated clay into the treated zone causing a retarding of consolidation settlement in the latter. A study of the effect of drained-treatment width and surcharge width showed that these parameters significantly affect the rate of consolidation settlement in the treated zone, and therefore it is important to consider these parameters in the design of drains.