A COMPARATIVE FIELD STUDY OF ROCK STRESS DETERMINATION TECHNIQUES.
MINNESOTA UNIV MINNEAPOLIS SCHOOL OF MINERAL AND METALLURGICAL ENGINEERING
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Numerous different techniques have been developed for the determination of in-situ stresses in rocks. Generally, each system has been designed and calibrated or tested independently of the others. The purpose of this research was to make a comparative study of several different techniques under the same carefully controlled field conditions. A four foot square on a quarry floor was first instrumented and then relieved from any regional stresses by drilling four slots 4 ft. 6 in. long and 9 ft. deep at right angles around the instrumented region. The piece of rock isolated by this way was then restressed by means of flat jacks inserted in the slots. With this arrangement it was possible to compare the various techniques of rock stress determination in either uniaxial or biaxial stressfields generated by pressurizing the opposite pairs of flat jacks. Results strongly suggest that data obtained from current techniques of stress determination cannot be relied upon within plus or minus 20 to 30 of the mean values, even under carefully controlled conditions. Author
- Geology, Geochemistry and Mineralogy