JPS57205627A - Excavator for cutting edge side of caisson - Google Patents

Abstract

PURPOSE:To enhance the settling accuracy of a caisson by a method in which the cutting edge side of a caisson for constructing an underground LNG storage tank, etc., is excavated using undermining technique by the cutter chain of an excavator moving along a rail in the inner wall of the lower part of the caisson. CONSTITUTION:Under the condition that an inclining jib 8 is retreated from the ground below the cutting edge slope 6, a running driver 3 is operated, and an excavator 20 is run along the inner wall 2 of a caisson until it reaches a place where the excavation is to be performed. Then, an inclining jib 8 is moved forwards slantly downwards along right under the cutting edge slope 6 while driving a cutter chain 11 circularly, and the side ground of the cutting edge slope 6 is openly ecxcavated by the cutter chain 11. After the undermining is made to below the outside end of the cutting edge slope 6, the excavator 20 is retreated slantly, the driver 3 is operated to run the base 4 of the excavator 20 to the next position to be excavated. The operations are repeatedly performed to undermine the ground beneath the cutting edge slope 6 over as much as the thickness of the chain 11. Thus, the caisson can be settled little by little uniformly over its all circumference.