Abstract: At least one guide shaft is equipped on one or both sides of a plurality of drilling shafts arranged on a line; and a jet nozzle is equipped with said guide shaft. A multi-shaft drilling unit, equipped with preferably three auger shafts, is used to develop a continuous wall under the ground. In such a unit, a housing for maintaining a pitch between the auger shafts includes a housing comprising: a primary gear rotating around the central auger shaft; a pair of secondary gears engaging with the primary gear; a primary bevel gear integral to the primary gear; a secondary bevel gear engaging with said primary bevel gear and fixed to a rotary shaft which rotary shaft is perpendicular to a straight line connecting the center lines of auger shafts; and cutters fixed at both ends of the rotary shaft.

Abstract: The present invention relates to a multi-shaft kneading auger system having a plurality of kneading shafts or rotating shafts used to form a continuous wall in the ground. Grouting blades driven by chains, are positioned near the lower ends of the kneading shafts. A grouting edge of the blade forms a predetermined angle with the surface of the kneading shafts. Also, a scraping apparatus is formed in a part of the rotating shafts. The scraping apparatus comprises a supporting member laterally supported in the part of the rotating shafts, plain blades vertically movably supported on the supporting member and substantially located on common tangential lines of the rotational surfaces of the grouting blades, a coupling member including rollers and laterally coupling the plain blades, and cams provided in the part of the rotating shafts and adapted to engage with the rollers.