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Geometric Relationship Between Geologic Structure and Ground Stresses Near Atlanta, Georgia.
NTIS: PB 190 973 :24 pages
An investigation of geologic structure on macroscopic, mesoscopic, and microscopic scales was conducted on near-surface igneous and metamorphic rocks in which the existing stress field was determined by in situ methods. A consistent ne-sw orientation of the maximum compressive stress in the horizontal plane at four of five test localities appears due to the intrusion of nw-trending diabase dikes. Structural features at the mesoscopic scale show no consistent directional relationship to determined stress directions. Petrofabric diagrams of open microfractures show preferred orientations, but these are not consistently related to the orientations of larger structural feature, such as joints, foliation, or mineralized shear zones. However, at five of six test sites the preferred direction of microfractures occurs nearly perpendicular to the maximum principal stress directions; an anomalous parallel relationship exists at a test site in an intrusive rock body. The results suggest that the open microfracture sub-fabric may provide a means for gaining information on the directional properties of stress fields. Such information can be obtained from oriented cores taken from holes which exceed the approximate 100-foot depth to which other in situ methods are presently limited.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 190 973
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division