Abstract: The apparatus includes two tools for forming holes in the subsoil without excavating it, which tools being coaxially mounted on a drill column. To the end of the drill column there is attached a hollow tool which is concealed when a skirt is in a lower position and exposed when the skirt is in an upper position. A soil displacing body is mounted on the drill column and above the tool. The soil displacing body is a hollow structure and has an upper opening wherethrough its inner space communicates with a concrete feeding tube and a lower opening closable by the skirt in its upper position. To construct a tubular pile the apparatus is driven into the subsoil whereby a design hole is formed, then the apparatus is withdrawn from the hole with a simultaneous filling of the hole with a concrete mix through the concrete feeding tube, the soil displacing body, and the lower opening provided therein.

Abstract: A tool comprises two coaxial casings, a leading and a trailing ones, connected by a tubular element provided with ports for discharging a fixing material into a hole. The leading casing comprises a cylindrical portion, and frontal and rear conical tips provided with spiral tapered surfaces intended for consolidating soil. The trailing casing has a cylindrical portion of a greater diameter than that of the cylindrical portion of the leading casing. In the trailing casing there is provided an axial duct communicating with a cavity of the coupling element for supplying a fixing material. A method of forming holes having fixed walls includes formation of a pilot hole using the leading casing, and subsequent formation of a hole of a predetermined diameter using the trailing casing in the advancing sinking of a pilot hole.

Abstract: A tool for the formation of holes without extracting the soil comprises a body having a cylindrical calibrating portion, coaxial portions with surfaces for the compaction of the soil and radii decreasing stepwise in the direction away from the calibrating portion, and terminating in an end piece. The body has also transition portions with surfaces for the compaction of the soil, forming a smooth transition from a coaxial portion with a larger radius to an adjacent coaxial portion with a smaller radius. The surface for the compaction of the soil of each coaxial portion is a conical surface having the configuration of a ribbon wound from the calibrating portion to the end piece and comprising the transition portions.

Abstract: A tool comprises a body having coaxial portions radially defined by soil compaction surfaces of step-down radii from the sizing portion to the tool tip. The soil-compaction surface of each portion is a cylindrical surface generated by a generatrix of a predetermined length extending parallel to the tool axis and bounded by two parallel helices of one and the same helix angle. These surfaces are successively conjugated by transition portions defined by a cylindrical surface whose generatrix is parallel to the tool axis and uniformly approaches the same axis to thereby form a smooth transition from the surface of the body portion of a greater radius to that of an adjacent body portion of a smaller radius. A method of forming a hole by the same tool is also described.