Analysis of in-situ rock joint strength using digital borehole scanner images
- Univ. of California, Berkeley, CA (United States)
The availability of high resolution digital images of borehole walls using the Borehole Scanner System has made it possible to develop new methods of in-situ rock characterization. This thesis addresses particularly new approaches to the characterization of in-situ joint strength arising from surface roughness. An image processing technique is used to extract the roughness profile from joints in the unrolled image of the borehole wall. A method for estimating in-situ Rengers envelopes using this data is presented along with results from using the method on joints in a borehole in porphyritic granite. Next, an analysis of the joint dilation angle anisotropy is described and applied to the porphyritic granite joints. The results indicate that the dilation angle of the joints studied are anisotropic at small scales and tend to reflect joint waviness as scale increases. A procedure to unroll the opposing roughness profiles to obtain a two dimensional sample is presented. The measurement of apertures during this process is shown to produce an error which increases with the dip of the joint. The two dimensional sample of opposing profiles is used in a new kinematic analysis of the joint shear stress-shear deformation behavior. Examples of applying these methods on the porphyritic granite joints are presented. The unrolled opposing profiles were used in a numerical simulation of a direct shear test using Discontinuous Deformation Analysis. Results were compared to laboratory test results using core samples containing the same joints. The simulated dilatancy and shear stress-shear deformation curves were close to the laboratory curves in the case of a joint in porphyritic granite.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 10107663
- Report Number(s):
- LBL-36126; ON: DE95004684; TRN: AHC29505%%21
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
47 OTHER INSTRUMENTATION
54 ENVIRONMENTAL SCIENCES
REMOTE VIEWING EQUIPMENT
PERFORMANCE
GEOLOGIC FISSURES
ROCK MECHANICS
ROUGHNESS
IMAGE PROCESSING
SHEAR PROPERTIES
EXPERIMENTAL DATA
WELL LOGGING
BOREHOLES
580000
440400
540250
GEOSCIENCES
WELL LOGGING INSTRUMENTATION
SITE RESOURCE AND USE STUDIES