Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Deformation or change in stress after fracture – cutting – or...
Patent
1983-02-17
1985-01-01
Myracle, Jerry W.
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Deformation or change in stress after fracture, cutting, or...
73784, E21B 4900
Patent
active
044910223
ABSTRACT:
The state of stress in a rock mass surrounding a borehole (21) can be estimated by measuring the initial dimensions of the borehole, cutting a cone-shaped opening extending outwardly from the borehole having a bottom wall (44), and cutting a conical slot (45) from the bottom wall (44) of the cone-shaped opening outwardly from the borehole at an angle to the axis of the borehole. The release of stress on the rock between the borehole and the conical slot results in a change in the dimensions of the borehole. An apparatus for carrying out the measurements includes one or more cutting arms (27) pivotally mounted to a main support housing (26) and capable of being rotated thereon while being pivoted outwardly to cut the cone-shaped opening. Extensible inner stems (41) fit within the cutting arms (27) and have cutting heads (40) at their ends such that when the inner stems are driven outwardly from the cutting arms (27) the cutting heads (40) will cut the conical slot to substantially relieve the stresses on the element of rock defined between the borehole (21), the bottom wall (44) of the cone-shaped opening and the slot (45). The displacements of points on the borehole wall are measured by displacement sensors 33 mounted to the main support housing at a position just below the position of the bottom wall (44).
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V. E. Hooker et al.: Improvements in the Three Component Borehole Deformation Gage and Overcoring Techniques, United States Department of the Interior, Bureau of Mines Report of Investigations 7894/1974.
W. G. Austin: Development of a Stress Relief Method With a Three-Directional Borehole Deformation Gage, United States Department of the Interior, Bureau of Reclamation Report REC-OCE-70-10, Mar. 1970.
Myracle Jerry W.
Wisconsin Alumni Research Foundation
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