PURPOSE: To facilitate chipping operation and to shorten the term of work and reduce the cost of construction by filling the inside of a cylindrical tube with sand between main reinforcements arranged before and behind the inside of a shaft wall and disposing a plurality of void tubes, at both end faces of which muddy-water intruding sections are mounted.
CONSTITUTION: The inside of a cylindrical tube 5 made of cardboard is filled with sand 6, and a plurality of void tubes C, both end sections of which are blocked by cloth pieces 8 with a large number of small through-holes 7, are suspended to a cross tie reinforcement 2 disposed between front and rear main reinforcements 1, 1 positioned to the face cutting section B of a reinforced cage through filaments such as tying-wire. When the reinforced cage is built into an excavated pit, muddy water is intruded into the void tubes C through the small through-holes 7, the crushing of the void tubes C is prevented, and the deformation of the void tubes C is obviated even by sand 6 on concrete placing. When the face cutting section B is bored, the cylindrical tube 5 is composed of cardboard and a filler of sand 6, thus eliminating trouble in chipping operation, then easily removing sections to be chipped.
ARAGAI MICHIO
TOMIKI TADASHI
OGAWA KATSUMASA
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