Method and apparatus for constructing reinforced concrete walls in the earth

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. The material of the backfill is washed out of alternate pipes (water is injected in one, soil and water exits from the next pipe). As the wall section is lowered, the next concrete wall section is formed and concreted in sequence. As each wall section is formed, the next pipe sections are coupled to the protruding sections and the next reinforcing elements are secured to the protruding reinforcing bars of the element that has been lowered. The sequence continues until the whole structure has reached the design depth, or a bearing stratum or rock. Finally, as the structure reaches the design depth, the pipes can be used as grout pipes to extend a drill curtain below the bottom, fill the contact between the structure and the rock and grout any voids left around the structure by washing of the backfill.

Dependencies are inferred from the claim text.