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Title: Fracture detection in crystalline rock using ultrasonic shear waves

Abstract

An ultrasonic shear wave reflection profiling system for use in the detection of water-filled cracks occurring within a crystalline rock mass is being tested in a laboratory environment. Experiments were performed on an irregular tensile crack induced approximately 0.5 m below one circular face of a 1.0-m-dia, 1.8-m-long granite cylinder. Good reflection data were obtained from this irregular crack with the crack either air filled or water filled. Data were collected that suggest a frequency-dependent S/sub H/ wave reflection coefficient for a granite-water interface. Waves that propagate along the free surface of a rock mass (surface waves) can severely hinder the detection of reflected events. Two methods of reducing this surface wave noise were investigated. The first technique uses physical obstructions (such as a slit trench) to scatter the surface waves. The second technique uses a linear array of receivers located on the free surface to cancel waves that are propagating parallel to the array (e.g., surface waves), thus enhancing waves with propagation vectors orthogonal to the linear array (e.g., reflected events). Deconvolution processing was found to be another method useful in surface wave cancellation.

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
OSTI Identifier:
6082110
Report Number(s):
LBL-7051; SAC-19
TRN: 79-019152
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 58 GEOSCIENCES; GEOLOGIC FISSURES; DETECTION; ROCKS; SEISMIC SURVEYS; CRACKS; GEOLOGIC DEPOSITS; RADIOACTIVE WASTE DISPOSAL; REFLECTION; SHEAR; ULTRASONIC WAVES; WATER; WAVE PROPAGATION; GEOLOGIC STRUCTURES; GEOPHYSICAL SURVEYS; HYDROGEN COMPOUNDS; MANAGEMENT; OXYGEN COMPOUNDS; SOUND WAVES; WASTE DISPOSAL; WASTE MANAGEMENT; 052002* - Nuclear Fuels- Waste Disposal & Storage; 580300 - Mineralogy, Petrology, & Rock Mechanics- (-1989)

Citation Formats

Waters, K H, Palmer, S P, and Farrell, W E. Fracture detection in crystalline rock using ultrasonic shear waves. United States: N. p., 1978. Web. doi:10.2172/6082110.
Waters, K H, Palmer, S P, & Farrell, W E. Fracture detection in crystalline rock using ultrasonic shear waves. United States. https://doi.org/10.2172/6082110
Waters, K H, Palmer, S P, and Farrell, W E. 1978. "Fracture detection in crystalline rock using ultrasonic shear waves". United States. https://doi.org/10.2172/6082110. https://www.osti.gov/servlets/purl/6082110.
@article{osti_6082110,
title = {Fracture detection in crystalline rock using ultrasonic shear waves},
author = {Waters, K H and Palmer, S P and Farrell, W E},
abstractNote = {An ultrasonic shear wave reflection profiling system for use in the detection of water-filled cracks occurring within a crystalline rock mass is being tested in a laboratory environment. Experiments were performed on an irregular tensile crack induced approximately 0.5 m below one circular face of a 1.0-m-dia, 1.8-m-long granite cylinder. Good reflection data were obtained from this irregular crack with the crack either air filled or water filled. Data were collected that suggest a frequency-dependent S/sub H/ wave reflection coefficient for a granite-water interface. Waves that propagate along the free surface of a rock mass (surface waves) can severely hinder the detection of reflected events. Two methods of reducing this surface wave noise were investigated. The first technique uses physical obstructions (such as a slit trench) to scatter the surface waves. The second technique uses a linear array of receivers located on the free surface to cancel waves that are propagating parallel to the array (e.g., surface waves), thus enhancing waves with propagation vectors orthogonal to the linear array (e.g., reflected events). Deconvolution processing was found to be another method useful in surface wave cancellation.},
doi = {10.2172/6082110},
url = {https://www.osti.gov/biblio/6082110}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 1978},
month = {Fri Dec 01 00:00:00 EST 1978}
}