BOTTOM PART WATER BARRIER STRUCTURE AND UNDERGROUND INSTALLATION METHOD FOR THE SAME

PROBLEM TO BE SOLVED: To build a reliable water barrier layer economically. SOLUTION: For example, a propulsion machine having at least two units of propulsion apparatuses connected by a grooving steel plate is advanced under the ground from a starting base A which is installed on the side of the ground of a mentioned region 11 containing polluted soil toward an arrival base B installed on the opposite side of the ground and is made to arrive at the base B. Next, a water barrier sheet 16 is attached to the propulsion machine which arrived at the base B, and the propulsion machine is extracted to the starting base side while the sheet 16 being supplied so that the sheet 16 can be laid in the cut channel 21 which was cut and formed by the grooving steel plate. In a drilled hole 15 formed by extracting the propulsion machine, while the end part of the sheet 16 being buried, or after being buried, an injection solidification material 17 is packed and solidified so that the sheet 16 and the solidification material 17 is integrated to form water barrier structure 10 which covers the ground of a prescribed region 11 from below.