Applications of surface-layer improvement technique in land reclamation with dredger soil

Dredger soil once was treated as waste and abandoned to the appointed sites or the nearby ocean, which had resulted in serious environment pollution and high costs. Since the viewpoint of "Utilize Dredger soil Valuably" was proposed in 1980s, dredger soil has been used as the hydraulic fill material in reclamation works, which can meet the requirements of land expansion and avoid the dilemma of seeking the special sites to deposit vast dredger soil. However, most of the new hydraulic fill soil is the floating or fluid mud and has high water content but little bearing capacity, so it is difficult for the traditional treatment methods to improve the ultra-soft foundation. Based on the improvement mechanism of vacuum preloading, the surface-layer improvement technique without sand cushion was developed and has been applied successfully in practices. The applications showed that the surface-layer improvement technique without sand cushion improved the bearing capacity of ultra-soft foundation substantially.