USE OF THE RESISTIVITY DIPMETER FOR DISCONTINUITY ASSESSMENT AND STABILITY DESIGN OF A MAJOR CUTTING

The slope stability assessment and design of a deep cutting for the planned A38 trunk road in East Cornwall, England, is discussed. The Grey Mare Plantations cutting was up to 23m deep, in Devonian strata with metamorphosed sandstones, siltstones, and mudstones. To classify the rock weathering, a grading system was devised, based on scales I to VI of British Standard BS5930. In such ground, mechanical downhole techniques would produce sparse unreliable information, so that a 4.5m long resistivity dipmeter was used instead. The dipmeter was used to analyse 17 of the 23 boreholes drilled in the area, to supplement and correlate with the results of a structural mapping survey of surface outcrops and borehole core logs. It was operated from an all-terrain vehicle, in which a personal computer and its printer produced the logs as the test proceeded. Strength tests were conducted on the cutting rock, which had many discontinuities. The structure, discontinuities, and permeability of the cutting rock were investigated. The dipmeter results were compared with those of the borehole logs. Failure mechanisms in the rock are discussed. Four techniques, to measure the dip and orientation of the discontinuities, were reviewed. For the covering abstract see IRRD 883023.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0727725130
• Corporate Authors:

  Thomas Telford Limited

  London,   United Kingdom 
• Authors:
  • GUY, D G
  • O'CALLAGHAN, D A
• Conference:
  • ADVANCES IN SITE INVESTIGATION PRACTICE. PROCEEDINGS OF THE INTERNATIONAL CONFERENCE HELD IN LONDON ON 30-31 MARCH 1995
• Publication Date: 1996

Language

• English

Media Info

• Features: References;
• Pagination: p. 762-73

Subject/Index Terms

• TRT Terms: Boreholes; Classification; Conferences; Cutting (Earthwork); Data collection; Design; Digital computers; Evaluation and assessment; Failure; Maps; Measurement; Measuring instruments; Permeability; Resistance (Electricity); Rocks; Sandstones; Slope stability; Standards; Strength of materials; Test procedures; Weathering
• Uncontrolled Terms: Site investigation
• Geographic Terms: United Kingdom
• ITRD Terms: 6155: Apparatus (measuring); 5711: Bore hole; 8513: Classification; 8525: Conference; 2812: Cutting (earthworks); 8623: Data acquisition; 9011: Design (overall design); 8673: Digital computer; 9020: Evaluation (assessment); 5520: Failure; 4074: Map; 6136: Measurement; 5921: Permeability; 6916: Resistance (electr); 4154: Rock; 4104: Sandstone; 5722: Site investigation; 5783: Slope stability; 187: Specification (standard); 5544: Strength (mater); 6288: Test method; 8119: United Kingdom; 5281: Weathering
• Subject Areas: Design; Geotechnology;

Filing Info

• Accession Number: 00729299
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• ISBN: 0-7277-2513-0
• Files: ITRD
• Created Date: Dec 12 1996 12:00AM