CONSTRUCTION OF BOTTOM SLAB OF OPEN CAISSON

PURPOSE:To raise the efficiency of construction by a method in which a caisson incorporated with a bottom slab supporter and a pusher therefor is settled down into the ground, the bottom slab supporter is pushed out of the caisson body and buried in concrete placed to construct the bottom slab. CONSTITUTION:The cutting edge 11 of a non-cylindrical concrete caysson 10 having a cutting edge groove 12 on its tip is tapered in such a way that the inside diameter is gradually increased toward the tip of the side wall of the caisson 10. While constructing the caisson 10, the inside bottom ground is excavated in a repeated manner to settle the caisson 10 into the ground down by its own weight. After the lower bars 21 in the bottom slab 20 are settled down, the support metal 32 is projected from the inner wall of the caisson 10 by operation of an oil-pressure jack 31, and after the upper bars 22 in the slab 20 are settled down, underwater concrete is placed to the bottom and hardened and also water is discharged to construct the bottom slab 20. The bottom slab can thus be constructed even at deeper depth.