WATER CUTOFF STRUCTURE OF ENTRANCE PART FOR USE IN ACEMOLE CONSTRUCTION METHOD

PROBLEM TO BE SOLVED: To provide a water cutoff structure of an entrance part for use in acemole construction method capable of preventing the spill of earth and sand and underground water which may emanate when a propulsion machine starts up or when it arrives at a goal. SOLUTION: The acemole construction method uses a propulsion machine having a mud passing channel of a recessed cross section along the longitudinal direction of its outer peripheral wall. The entrance part is formed of an entrance member including an entrance box 1 installed on the wall of a shaft on the natural ground side (a) and having an opening through which the propulsion machine passes; entrance packing 2 installed on the front surface of the entrance box and consisting of first packing 210, second packing 220 and third packing 230; and a packing gland 3 for restraining the inflation of the entrance packing 2 caused by a gas bag 4. The gas bag 4 which is inflated by gas sealed therein to extend along the recessed wall surface of the mud passing channel of the propulsion machine to seal the channel is provided oppositely to the channel of the propulsion machine.