ASSESSING ROCK DISCONTINUITIES

The article describes the use of a Schmidt hammer and grid on a tunnel face to determine the Schmidt reduction index. The index has been shown to be related to excavation rates, while increases in these rates have been attributed to the fractured state of the rock mass. The authors consider that the relationships established for four fathom mudstone should apply to most sedimentary rocks, though the values of intercepts and gradients will vary from site to site. During the investigations, seismic methods were also used to evaluate the quality of a rock mass. The use of small, ultrasonic instruments was found to be unsuitable due to attenuation characteristics of fractured rock. /TRRL/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/0041414X
• Corporate Authors:

  Morgan-Grampian Limited

  30 Calderwood Street
  London SE18 6QH,   England 
• Authors:
  • Young, R P
  • FOWELL, R J
• Publication Date: 1978-6

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 45-48
• Serial:
  • Tunnels & Tunnelling International
  • Volume: 10
  • Issue Number: 5
  • Publisher: Progressive Media Markets, Ltd
  • ISSN: 0041-414X

Subject/Index Terms

• TRT Terms: Coefficients; Concrete tests; Evaluation and assessment; Excavation; Excavations; Hardness; Mass; Measurement; Measuring instruments; Mudstones; Pile hammers; Quality control; Rocks; Seismic prospecting; Test procedures; Tunneling; Tunnels; Ultrasonics
• Identifier Terms: Schmidt hammer
• Uncontrolled Terms: Discontinuity; Quality; Rock mass
• Old TRIS Terms: Seismoacoustic methods
• ITRD Terms: 6155: Apparatus (measuring); 6410: Coefficient; 9020: Evaluation (assessment); 5155: Excavation (process); 5914: Hardness; 9063: Quality; 4154: Rock; 6288: Test method; 3374: Tunnel; 6739: Ultrasonic
• Subject Areas: Bridges and other structures; Geotechnology; Highways; I43: Rock Mechanics;

Filing Info

• Accession Number: 00189526
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Files: ITRD, TRIS
• Created Date: Apr 12 1979 12:00AM