METHOD AND DEVICE FOR ASSESSING EXTREME STRESSED CONDITION OF ROCK Russian patent published in 1998 - IPC

FIELD: mining industry. SUBSTANCE: this is aimed at ensuring structural stability of mine workings and safety performance of underground operations in mining and other industries. Method implies drilling of bore-hole from mine working in zone of support pressure, measuring of radial and axial displacements of rock, and interpretation of measurements. Bore-hole is drilled in zone of support pressure relative to stratum lying components, measured are radial and axial displacements of rock. Used as characteristics of stressed condition are first invariant of deformation tensor and second invariant of deformation deviator. Then, diagram is plotted for dependence of first invariant of deformation tensor versus time; and according to point of passing first invariant through maximum, determined is time moment of coming extreme condition of rock. Corresponding value of relative power strength of material is calculated according to certain formula. Instrument for measuring deformation of rock is provided with movable marker, additional converter for measuring displacements of rock along bore-hole axis with its core being connected to end of movable marker through movable head of instrument relative to bore-hole axis. Movable marker is located on bore-hole axis behind body of device. Additional converter is built in end of device. Movable marker and guide unit form together base of device at determined deformation of rock along bore-hole axis. EFFECT: higher efficiency. 3 dwg