Abstract
A method of improving soft clayey deposit by combining Cap-drain (CPVD) with vacuum pressure is described. The method uses a surface or subsurface soil layer as a sealing layer and no need to place an air-tightening sheet on the ground surface. It is explained that the method has advantages for situations of (a) a higher air/water permeability layer existed on ground surface, and (b) combing vacuum pressure with embankment load. A case history of consolidating a reclaimed clayey deposit by combining CPVD and vacuum pressure is analyzed and discussed. The site was in an under-consolidation state before starting the project. It is shown that the method is effective for this site. The back-calculation shows that for this under-consolidation deposit, vacuum pressure caused almost plane strain type isotropic deformation at near the ground surface.
