Method and system for measuring three-dimensional displacement

A method of measuring three-dimensional displacement of a mass having an end surface, comprising the steps of:

• providing a displacement indicating means on the end surface of the mass for indicating at least a fraction of three-dimensional displacement of the mass;
• arranging a measuring means for measuring displacement so as to be free to displace relative to the mass and in opposition to the displacement indicating means;
• measuring relative three-dimensional displacement of the mass by detecting displacement of the displacement indicating means relative to the measuring means with the measuring means;
• wherein the displacement indicating means comprises a concave surface formed by a curved surface that converges from an opening end to a bottom end;
• wherein the displacement measuring means comprises a displacement measuring device arranged opposite to the concave surface that, in said step of measuring, measures the relative distance to the concave surface along a circumferential trace by rotating about a center axis of the concave surface while maintaining a tilt angle relative to the center axis so as to circumferentially scan the concave surface;
• analyzing the displacement of the circumferential trace on the concave surface associated with the displacement of the mass on the basis of the relative distance measured by the displacement measuring device;
• wherein the mass comprises a first cylindrical member arranged at one side of a discontinuous surface in a bore hole formed across the discontinuous surface, and the displacement measuring device comprises a second cylindrical member positioned at the other side of the discontinuous surface, the displacement measuring device measuring the displacement of the first cylindrical member relative to the second cylindrical member across the discontinuous surface;
• and
• wherein the discontinuous surface is a crack in a rock, the displacement of the rock at the crack being measured by measuring the displacement of the first cylindrical member relative to the second cylindrical member.

A three-dimensional displacement measuring system for measuring displacement of a mass, comprising:

• a displacement indicating means on an end surface of the mass for indicating at least a fraction of three-dimensional displacement of the mass;
• a measuring means arranged so as to be free to displace relative to the mass and in opposition to said displacement indicating means for measuring relative three-dimensional displacement of the mass by detecting displacement of said displacement indicating means relative to said measuring means with said measuring means;
• wherein said displacement indicating means comprises a concave surface formed by a curved surface that converges from an opening end to a bottom end;
• wherein said displacement measuring means comprises a displacement measuring device arranged opposite to said concave surface for measuring the relative distance to said concave surface along a circumferential trace by rotating about a center axis of said concave surface while maintaining a tilt angle relative to the center axis so as to circumferentially scan said concave surface;
• means for analyzing the displacement of the circumferential trace on said concave surface associated with the displacement of the mass on the basis of the relative distance measured by said displacement measuring device;
• wherein the mass comprises a first cylindrical member arranged at one side of a discontinuous surface in a bore hole formed across said discontinuous surface, and said displacement measuring device comprises a second cylindrical member positioned at the other side of said discontinuous surface;
• and
• wherein said bore hole is formed in a rock and said discontinuous surface is a crack in the rock.