PURPOSE: To prevent cracks from occurring on the surface of a solidified ground by a method wherein a net-like incorruptible reinforcing material is laid over the surface of a weak ground and after that, the reinforcing material is buried in solidifying agent-mixed soft earth that is laid over the surface layer.

CONSTITUTION: Water is dammed up with a revetment 1, and after reclamation is made with dredged earth 2 up to a height, approximately 2-3m lower than the planned height, a net-like reinforcing material 3 made of synthetic resin or the like is laid afloat approximately 50cm above the surface of the dredged earth 2, and the reinforcing material is fixed with an anchor 4 at its land-side end. Then dredged earth 5, mixed with a solidifying agent, is laid over the dredged earth 2 and the reinforcing material 3 is taken into the layer of the dredged earth 5 and is buried therein. As a result, a solidified ground 8, reinforced by the reinforcing material 3, can be constructed over the layer of the dredged earth 2, and thereby troubles including breakups can be prevented even though cracks occurs on the solidified ground 8.