METHOD OF PRECEDING WATERPROOF CONSTRUCTION

PROBLEM TO BE SOLVED: To provide a method of preceding waterproof construction of a bored earth-retaining wall before constructing an underground structural skeleton, allowing a cement-based material equivalent to a concrete or a mortar to closely attach to irregularities of the earth-retaining wall for preventing formation of a water path, to form no weak point resulting from joints accompanied by sheets, and not to be damaged during construction of the skeleton.SOLUTION: Before a structural skeleton of an underground structure is constructed, a waterproof construction is performed to form a water cut-off layer on a bored earth-retaining wall by spraying a fiber reinforcement cement composite with multiple fine cracks (HPFRCC) exhibiting a tensile strain of 1% or more at a material age of 28 days to a thickness of 5 to 150 mm.