UNDERWATER EXCAVATOR FOR CAISSON

PURPOSE: To promote automation of work by providing plural rails disposed on the inner periphery of a caisson, an upper clamp and a lower clamp, a traverse link, a traverse jack, a clamp jack, a cutting jack and the like. CONSTITUTION: Clamp jacks 10 of equalizers 11A, 11B are driven to be elongated to separate a lower clamp 9 from the lower surface of a rail 60, and a traverse jack 7 is driven to be elongated to displace the equalizers 11A, 11B along the rail 60. Subsequently, the jack 10 is driven to be contracted, whereby the lower surface of the rail 60 is clamped by the clamp 9 and the equalizers 11A, 11B are fixed to the rails 60, 60. The clamp 9 for the equalizers 11C, 11D is released, the jack 7 is driven to be contracted to direct the equalizers 11C, 11D toward the equalizers 11A, 11W, and a frame 1 is moved to an excavating position. A cutting jack 5 is driven to be elongated to displace a cutter 2 toward the lower end 50A of the inner periphery of a caisson, and the lower end of the caisson is excavated.