BOREHOLE SHEAR TEST FOR STIFF SOIL

Borehold Shear Tests (BST) were performed at 3 sites in dense glacial till and at a fourth site in a much softer material (loess), using both conventional and modified shear plates. Characteristic properties are tabulated as well as the results of four comparison tests. Comparative studies of BST and triaxial shear results have been made with generally close agreement. The study concluded that where BST has been used in soft materials, results have been successfully used for analysis of landslides and design of footings. However, borehold shear tests using standard conventional shear plates do not appear to give reasonable results in all materials, particularly in stiff soils, where low values of cohesion accompanied by high values of friction angle are commonplace. The modified shear plates give more realistic and increasing its versitility. The plates and pulling strap are readily exchangeable with the conventional plates, and the rest of the apparatus remains unchanged. The conventional plates should continue to be used for routine testing in soft to medium soils because of the larger plate area (thus better sensitivity) and the time advantages in stage testing. Error from low cohesion is on the safe side for design. Where both types of plates are tried, the higher of the two shear envelopes should be used. Results should not be extrapolated beyond the pressure range tested and should be assumed to be on an effective stress i.e. drained basis.

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Filing Info

  • Accession Number: 00185429
  • Record Type: Publication
  • Source Agency: ASCE Journal of the Geotechnical Engineering Div
  • Report/Paper Numbers: ASCE 14125 Tech Note
  • Files: TRIS
  • Created Date: Mar 14 1979 12:00AM