SHAFT EXCAVATING CONSTRUCTION METHOD AND DEVICE

PROBLEM TO BE SOLVED: To excavate shafts different in size and shape by taking reaction on the internal wall of the shaft formed of a caisson, eccentrically rotating a cutter with a diameter smaller than the excavated cross section of the shaft, to excavate the shaft, and making eccentric mechanism replaceable. SOLUTION: A cutter 11 of an excavator 10 is fitted to an eccentric shaft 11 and rotated by a motor 15. An upper stage gripper 19 and an lower stage gripper 20 of an elevating device 18 are alternately brought into pressure contact with the internal wall of a caisson 1 so as to move the cutter 11 in a measuring worm form by an elevating jack 21. Excavation is performed while filling the inside of the caisson 1 with water and taking reaction on the internal wall of the caisson. A pressure device 2 is actuated to sink the caisson 1 simultaneously with excavation by the cutter 11. The cutter 11 is provided with a copy cutter 24 to excavate under a cutting edge of the caisson 1. Press-in resistance of the caisson 1 is therefore reduced to cope with deformed excavation and inclination correction. A hydraulic jack and an expansion arm are used for a crankshaft 14 to make the eccentric quantity variable so as to be able to cope with shafts different in size and shape.