Construction method and device for execution of a cast in-situ pile with multiple diameters decreasing with depth

A drilling device with continuous flights for execution of a cast in-situ pile into ground, the cast in-situ pile having a first section having a first diameter and at least one other section disposed below the first section and having a reduced diameter that is smaller than the first diameter, the drilling device comprising a first drilling tool, a second drilling tool, and a coupling-decoupling device that allows the first drilling tool to be fastened to the second drilling tool, and a gliding system;

• wherein the first drilling tool comprises an outer diameter that corresponds to the first diameter, a central continuous hollow space which allows insertion of at least the second drilling tool, a central spacer having a tubular shape disposed within the central continuous hollow space to act as a centering device for the second drilling tool within the central continuous hollow space and to allow soil excavated by the second drilling tool to be transported upwards, and a flange fixed onto an upper portion of the first drilling tool;
• wherein the second drilling tool comprises an outer diameter that corresponds to the at least one other section of the cast in-situ pile having a reduced diameter;
• and
• wherein the coupling-decoupling device comprises a mandrel having a tubular shape or a clamping profiled shape, an array of metallic wedges, a driving system acting on the array of metallic wedges by hydraulic or mechanical or electro-mechanical force that drives one or more blocking pads to fasten onto the second drilling tool;
• and
• wherein the one or more blocking pads are configured to slide through the gliding system over the flange.

A drilling device with continuous flights for execution of a cast in-situ pile into ground, the cast in-situ pile having a first section having a first diameter and at least one other section disposed below the first section and having a reduced diameter that is smaller than the first diameter, the drilling device comprising a first drilling tool, a second drilling tool, and a coupling-decoupling device that allows the first drilling tool to be fastened to the second drilling tool;

• wherein the first drilling tool comprises an outer diameter that corresponds to the first diameter, a central continuous hollow space which allows insertion of at least the second drilling tool, and a central spacer having a tubular shape disposed within the central continuous hollow space to act as a centering device for the second drilling tool within the central continuous hollow space and to allow soil excavated by the second drilling tool to be transported upwards;
• wherein the second drilling tool comprises an outer diameter that corresponds to the at least one other section of the cast in-situ pile having a reduced diameter;
• and
• wherein the coupling-decoupling device comprises a geared transmission that allows the drilling device to rotate the first drilling tool at a different speed rate compared to a rotation of the second drilling tool when the first drilling tool and the second drilling tools are coupled together and wherein the rotation of the first drilling tool can be in a same direction or an opposite direction as the rotation of the second drilling tool.