Abstract: A method for water leakage prevention in a portion connecting a first pipeline to a second pipeline having one end thereof in communication with a portion of the first pipeline is provided. This method includes the steps of passing elastically deformable drawing means from the other end of the second pipeline to one end of the first pipeline; engaging an impermeable cut-off member, having an expandable hose portion and a flange portion provided integrally with one end of the hose portion, with the drawing means at one end of the first pipeline at the hose portion; drawing the cut-off member into the first and second pipelines by drawing back the hose portion of the drawing means toward the other end of the second pipeline; and disposing the cut-off member in the first and second pipelines, so that the flange portion is positioned within the first pipeline and the hose portion extends within the second pipeline.

Abstract: A cut-off material is provided, which includes an impermeable cutoff member (10, 70) provided with an expandable hose portion (18, 72) and a flange portion (20, 74) formed integrally with one end of the hose portion. The cutoff member is disposed in first and second pipelines, so that the flange portion is positioned within the first pipeline (12) and that the hose portion is positioned within the second pipeline (14). The cut-off member is maintained, for example, by a base (24,54,82) that is wound to be radially expandable, so that the flange portion is brought into liquid tight contact with the inner surface of the first pipeline and the hose portion extends within the second pipeline.

Abstract: A boring-injection device comprises a fluid supplying hollow rod, a fluid discharge portion at the lower end of the rod, and a packer element inflatable from the rod to seal a space between the rod and a borehole wall at a desired depth position. The rod is surrounded by a sheath so that the packer element and fluid discharge portion can be protruded out of and retracted within the sheath in a body. They are retracted during the boring operation and protruded during injecting or investigating operation. The device can be used for practising a method of ground improvement or a method of ground investigation.

Abstract: A method for improving the ground or foundation by injecting a grouting agent from the tip end of a hollow injection rod inserted into a boring hole formed in the ground at site so as to infiltrate it into the ground to be solidified. The injection is carried out by varying an injection pressure or injection rate depending on the intensity, particularly, the tensile strength, of the ground so that no vein-like coagulation can be formed around the injection rod, and a columnar or spherical coagulation can be formed.