Process and apparatus of constructing a water tight underground pile wall

Claim 1

Apparatus for producing an elongated water-tight pile wall consisting of a row of mutually overlapping and mutually interpenetrating subsequently and previously formed adjacent pile wall portions such that one previously formed pile wall portion has a longitudinally extending groove therein and an adjacent subsequently formed pile wall portion has a longitudinally extending torque that is received in the groove to provide a water-tight interlock therebetween, comprising: a drive; a pair of longitudinally extending and generally parallel augers operative to excavate the earth for corresponding previously formed and subsequently formed pile wall portions each mounted on an end thereof for rotary motion to said drive and axially spaced by a distance less than the opertive width dimension of an auger to insure overlapping between adjacent previously formed and subsequently formed pile wall portions, each auger having a hollow shaft; a hollow cutting head having a tip mounted for rotation with the elongated shaft of each auger with the hollow of the head in fluid communication with the hollow of the shaft and in fluid communication with an aperture provided therefor in said tip; first and second pairs of elongated cutting blades each having ends having an operative generally rectangular geometry of dimensions selected to be less than the operative width of an auger to cut said grooves in adjacent previously formed pile wall portions; first means for mounting said first pair of cutting blades to one of said heads for motion between a first position where the lateral dimension defined between the ends of said first pair of cutting blades is less than the operative width dimension of its auger and a second position where the lateral dimension defined between the ends of said first pair of cutting blades is greater than the operative width dimension of its auger to allow the generally rectangular cutting blades to cut into the confronting surrface of the previously formed pile portions to form said longitudinally extending grooves to insure the mutual interpenetration of subsequently formed and previously formed adjacent pile wall portions; second means for mounting said second pair of cutting blades to the other one of said heads for motion between a first position where the lateral dimension defined between the ends of said second pair of cutting blades is less than the operative width dimension of its auger and a second position where the lateral dimension defined between the ends of said second pair of cutting blades is greater than the lateral width dimension of its auger to allow the generally rectangular cutting blades to cut into the confronting surface of the previously formed pile wall portion to form said longitudinally extending grooves likewise to insure the mutual interpenetration of adjacent subsequently formed and previously formed adjacent pile wall portions; and means coupled to said augers and to said first and second pairs of cutting blades for selectively moving said first and said second pairs of cutting blades to a selected one of their first and second positions.