... strength. The numerical model was calibrated with Obert and Duvall empirical pillar strength equation. A multi-variant regression has been used to established relationship between the modulus of deformation of the rock mass and the pillar strength for various pillar shapes and sizes. It can be concluded...

... show a satisfactory agreement with the general Obert and Duvall empirical equation. A major limitation of using Obert and Duvall empirical equation was revealed and a methodology was proposed to address this shortcoming. In conclusion, an empirical pillar strength equation has been proposed to evaluate...

... was made on the basis of the work of Obert et al, who in 1976 had documented the large increase in the normal stress on joints during shear tests under controlled transverse stiffness, as opposed to shear tests under controlled normal stress (Obert et al, 1976). Reservoir Characterization explosion...

... and burst occurrence. Dramatic advances in the field of digital computing have led to a resurgence in microseismics, the study of rock noises, as a method of inferring how mine strata respond to the stresses generated by mining. Microseismic monitoring had its beginnings in 1938 when Obert (1939) discovered...

... location obert emission acoustic emission activity transducer ACOUSTIC EMISSION AS APPLIED TO ROCK & SOIL ITS HISTORY, BASIC THEORY AND SEVERAL CASE STUDIES JAMES D. LEAIRD Applications Engineer Acoustic Emission Technology Corporation 1812J Tribute Road Sacramento, California 95815 MARCH 1980 615...

...Chapter 9 SUMMARY OF STRESS DETERMINATIONS MADE IN THE PROXIMITY OF UNDERGROUND OPENINGS by Leonard Obert Before 1957 a number of investigators reported stress determinations made on or near the surface of underground excavations. The usual procedure was to measure surface strains and to calculate...