EXECUTION OF STABILIZED SURFACE LAYER ON SOFT GROUND BY THE PNEUMATIC FLOW MIXING METHOD

Ground formed directly by grab-dredging soft cloy from the sea bed and pumping and filling using a pneumatic barge is very soft and has almost no bearing capacity. In order to beneficially use the reclaimed land, the bearing capacity should first be increased at points where soil improvement machines, such as those for installing vertical drains, are to work by constructing a stabilized surface layer. This paper describes an application of the pneumatic flow mixing method for constructing stabilized surface layer. This construction method of stabilized surface layer involves mixing a stabilizing agent during the process of pumping dredged clay and spreading the treated soil directly on the surface of the soft ground. It can dispose of dredged soil and produce stabilized surface layer at the same time, resulting in reduced construction period and costs. In Nanao City, Japan, the front of the quay wall was dredged to ensure the design water depth. The dredged soil was treated and used to fill the land behind the revetment. As a result, it is clear that the treated soil satisfied the aimed quality and the stabilized surface layer did not inhibit the installation of the drains.