Measuring device and system for the geomechanical characterization of a soil, and corresponding measuring method

Orbital drilling device (1) comprising, on the same frame (10):

• a motor (11),
• a cutting tool (12) rotated by said motor (11), about a rotation axis (A12),
• a first, inner, eccentric (13), comprising a hollow cylindrical body receiving said motor (11), said first eccentric (13) being configured to be mounted so as to be able to rotate with respect to the motor (11), said motor (11) being configured to be mounted substantially rotationally immobile with respect to the frame (10) about the axis (A12) of rotation of the cutting tool (12) on itself, the first eccentric (13) comprising an internal cylindrical wall (13i) of axis (A13i) and an external cylindrical wall (13e) of axis (A13e), the axis (A13i) of the internal cylindrical wall (13i) being offset by a distance (E13) with respect to the axis (A13e) of the external cylindrical wall (13e),
• a second, outer, eccentric (14), comprising a hollow cylindrical body receiving the first eccentric (13), mounted so as to be able to rotate with respect to the second eccentric (14), the second eccentric (14) comprising an internal cylindrical wall (14i) of axis (A14i) and an external cylindrical wall (14e) of axis (A14e), the axis (A14i) of the internal cylindrical wall (14i) being offset with respect to the axis (A14e) of the external cylindrical wall,
• a reference body (15), secured to the frame (10), comprising an internal cylindrical wall (15i) of axis (A15), receiving the second eccentric (14), mounted so as to be able to rotate with respect to the reference body (15),
• a first drive means (130) configured to rotate the first eccentric (13) with respect to the frame (10), at a rotation speed ω13,
• a second drive means (140) configured to rotate the second eccentric (14) with respect to the frame (10), at a rotation speed ω14, simultaneously with the rotation of the first eccentric (13) with respect to the frame (10),
• control means configured for producing a drilling to the required shape and dimensions through the following of a given path (T) by the cutting tool (12), by implementing the following steps:
• rotation of the cutting tool (12) on itself about the rotation axis (A12) thereof,
• continuous and simultaneous rotations of the first eccentric (13) with respect to the frame (10) at a rotation speed ω13, and of the second eccentric (14) with respect to the frame (10) at a rotation speed ω14 so that the cutting tool (12) also performs a rotation (R12) about the axis (A15) of the reference body (15) with a radius (D12) corresponding to the distance separating the axis (A15) of the reference body (15) from the axis (A12) of rotation of the cutting tool (12) on itself, and
• continuous and simultaneous control of the angular position θ13 and of the rotation speed ω13 with respect to the frame (10) of the first eccentric (13), and of the angular position θ14 and of the rotation speed ω14 with respect to the frame (10) of the second eccentric (14), so that the cutting tool (12) follows said given path (T), situated in a zone (Z12) defined between the circle (C) centered on the axis (A15) and of radius |E13-E14|, and the circle (C′) centered on the axis (A15) and of radius E13+E14,
• and wherein said control means are suitable for reproducing any path (T) of the cutting tool (12) in said zone (Z12) by continuous control during the drilling of the angular offset (θ14-θ13) between the angular position θ13 with respect to the frame (10) of the first eccentric (13) and the angular position θ14 with respect to the frame (10) of the second eccentric (14).