Abstract: An apparatus for constructing subterranean structures, soil-chemicals mixture or soil-agents mixture by using a multi-shaft auger machine to mix soil with a chemical hardener in situ in a borehole. As the auger shafts of the multi-shaft auger machine penetrate the soil, a plurality of lateral support structures shear soil and provide additional lateral support. The plurality of lateral support structures are spaced vertically by a length no greater than thirty feet. Additionally, soil fragmentation members attached to the lateral support structures fragment soil reconsolidations to aid in mixing of soil. The soil fragmentation members have a length no greater than the difference between the radius of at least one auger blade and the radius of the shaft and no less than one-third the difference between the radius of at least one auger blade and the radius of the shaft.

Abstract: Methods are provided for the constructing of subterranean soil-cement structures in situ. The methods utilize techniques designed to prolong the period of time in which an auger machine can operate in a bore hole without encountering difficulty due to the hardening of the soil-cement mixture. The techniques utilized include a preparatory drilling phase during which a lubricating slurry may be injected. This preparatory drilling serves to break up the soil and particularly if a lubricating slurry is used, reduce friction so that final drilling may progress more quickly. After preparatory drilling, final drilling takes place. Final drilling is divided into a downward and an upward phase. Either hardening or non-hardening slurry may be introduced and consolidated with the soil during the downward phase, but only hardening slurry is typically utilized during the upward phase of final drilling.

Abstract: An apparatus for constructing subterranean structures, soil-chemicals mixture or soil-agents mixture by using a multi-shaft auger machine to mix soil with a chemical hardener in situ. As the auger shafts of the multi-shaft auger machine penetrate the soil, spiral flights attached to the auger shaft above the initial auger blades assist soil in passing by supporting structures located between adjacent auger shafts. The spiral flights both assist in raising the soil beyond the supporting structures and also prevent reagglomeration of the soil prior to passing by the supporting structures. The spiral flights have a diameter less than that of the auger blades attached to the shaft below the spiral flights and have a connection ranging from 360 degrees to 720 degrees around the shaft.