To provide a construction method for an underground structure capable of reliably securing cut-off performance of the structure by being constructed by concomitantly using inverted lining construction and normal lining construction, and provide the underground structure and a precast block.
Earth retaining walls 3 are installed in a ground 1. An operation for excavating the ground 1 sandwiched between the opposed earth retaining walls 3 and an operation for installing precast blocks 5 along the earth retaining walls 3 are repeated to form precast side walls 6 made of the plurality of precast blocks 5 by inverted lining construction. The precast block 5 has a cut-off plate 25 provided on a back surface 23, and a section between the cut-off plates 25 arranged in upper and lower positions is cut off by a cut-off rubber 27. Subsequently, a cut-off sheet 37 is installed along the earth retaining wall 3 in such a manner as to overlap with a lap part 25a of the cut-off plate 25, between the precast side walls 6 adjacent to each other. After that, a reinforcing bar 39 is arranged between the precast side walls 6, and a cast-in-place concrete side wall is formed by normal lining construction.
IWASHITA ZENICHIRO
MORITA DAISUKE
MIYAGAWA KEITA
