Abstract: A method and apparatus for constructing large vertical boreholes and underground cut-off walls is disclosed. A drill rig assembly with double rotary heads drives a small diameter drill string and a much larger diameter drill string which is concentric with the smaller drill string and has a donut shaped drill bit configuration at the lower end thereof. Preferably, a steerable mud motor/drill is provided on one end of the small drill string and is guided to make as vertical a borehole as possible. In a preferred embodiment, the small inner drill is advanced to the full depth using the steerable mud motor/drill to achieve a high degree of verticality and a slight smaller casing is installed and used as a verticality guide for the much larger diameter outer drill string. In a further embodiment, the inner drill string is advanced a predetermined distance, then the outer string is advanced using the inner string as a verticality guide, these steps being repeated in alternating fashion to the final depth.

Abstract: A method and apparatus for constructing large vertical boreholes and underground cut-off walls is disclosed. A drill rig assembly with double rotary heads drives a small diameter drill string and a much larger diameter drill string which is concentric with the smaller drill string and has a donut shaped drill bit configuration at the lower end thereof. Preferably, a steerable mud motor/drill is provided on one end of the small drill string and is guided to make as vertical a borehole as possible. In a preferred embodiment, the small inner drill is advanced to the full depth using the steerable mud motor/drill to achieve a high degree of verticality and a slight smaller casing is installed and used as a verticality guide for the much larger diameter outer drill string. In a further embodiment, the inner drill string is advanced a predetermined distance, then the outer string is advanced using the inner string as a verticality guide, these steps being repeated in alternating fashion to the final depth.

Abstract: A novel underground impervious barrier is constructed by excavating a trench or slot along the desired line of the impervious barrier in the presence of a bentonite slurry. A double layered plastic film or sheet joined or folded at the bottom of the trench to form a sheath or envelope and open at the top and of sufficient vertical extent to extend above the ground and drape on both sides of the trench is installed in the trench and as the plastic sheath or envelope is installed in the trench it is hydraulically backfilled between the two facing surfaces thereof with a backfilling material having a greater density than the density of the bentonite slurry to sink the double layer plastic film or sheet to the bottom of the trench and displace the bentonite slurry forward in the trench toward the end being excavated.

Abstract: Improvement on the method and apparatus for forming reinforced concrete walls with continuous steel reinforcements is disclosed in Veder U.S. Pat. No. 3,310,952. The process includes the forming of a plurality of concrete panels, each panel having a reinforcing cage extending to proximate the joint between the concrete panels and one or more expansible joint reinforcing cages bridging the gap between the reinforcing cages in the adjoining panels. The expansible joint reinforcing cages are carried in carriers in an end stop pipe. Each expansible joint reinforcing cage is comprised of a vertical support bar having secured thereto a plurality of horizontally extending concrete anchor members rigidly secured to one surface of the vertical support bar.

Abstract: A system for constructing narrow underground walls utilizing the slurry trench method is disclosed wherein a first apparatus excavates from one end of a slurry filled trench and a second apparatus is utilized for filling the trench with a wall forming material and at least a part of the excavating and/or filling apparatus is floated on the slurry in the trench. In one disclosed embodiment, narrow cut-off walls are formed by excavating from one end of a slurry filled trench and backfilling the trench at the opposite end by depositing therein a mixture of excavated soil and bentonite slurry from the trench, and includes a relatively large float adapted to be immersed in the slurry to prevent loading on the trench walls and stabilizing the apparatus for excavating purposes.

Abstract: This invention relates to slurry method and apparatus for forming panelized concrete walls with a positive seal between joints. The invention is basically an improvement on the process disclosed in Veder U.S. Pat. No. 3,310,952. The slurry method or process includes the formation of a plurality of overlapping trench sections in the presence of a slurry, typically a thixotropic bentonite, with the overlapping ends between trench sections being maintained open by a hollow tubular pipe member. The joint between the concrete panels include a positive seal member bridging the gap between the adjoining panels. Portions of the positive seal members according to this invention are carried furled or folded in slots in the end stop pipe. Each furled seal portion is comprised of a vertical support bar having sealingly secured thereto a plurality of horizontally extending anchor and seal portions rigidly secured to one surface of the vertical support bar where the concrete is to be poured in a panel section.

Abstract: Reinforced concrete walls, particularly circular shafts are constructed in difficult and rocky ground by casting a pair of guide walls spaced apart a distance larger than the nominal thickness of the final wall structure and the trench excavation for the wall is carried out between the two guide walls. Initially, backfilling is of a plastic erodable mixture such as cement-bentonite, sand-cement-bentonite, which have no large aggregates. At the surface above the guide walls, forms are set for casting the reinforced structures which are to form the concrete wall per se and hollow pipes are embedded in the structure at spaced intervals, each with pipe couplings extending out of the concrete, along with the vertical runs of the steel reinforcing bars, for the next succeeding section. Water is then injected into the pipes gradually washing the erodable backfill material and facilitating the descent of the cast concrete section, which is lowered by jacks anchored to the guide walls.