INTERPRETATION OF IN SITU PERMEABILITY TESTS ON ANISOTROPIC DEPOSITS

To calculate the permeability of a soil from the results of in situ constant- or variable-head tests, one must know the intake factor for the porous tip used. The intake factor for a cylindrical tip of a piezometer is a function of its length and diameter only. No rigorous relationship has yet been derived, but an accurate empirical formula based on the best fit and previously published numerical solutions expresses the intake factor in a dimensionless form as a function of the ratio of the length to diameter of the tip. When tests are carried out in a horizontally bedded cross-anisotropic deposit (e.g., a laminated lacustrine clay), the permeability, calculated by assuming isotropy, will have a value intermediately between the horizontal and vertical permeabilities. If the ratio of these permeabilities is known from laboratory or other tests, a correction factor may be applied to the permeability (assuming isotropy) to determine the coefficients of permeability in the horizontal and vertical directions. The correction factor, which is a function of both the ratio of intake length to intake diameter and the ratio of the coefficient of the permeability in the horizontal position to that in the vertical position, is presented in graphical form to enable quick determination of the directional permeabilities.

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 43-48
  • Monograph Title: FROST, MOISTURE, AND EROSION
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00099653
  • Record Type: Publication
  • ISBN: 0309023807
  • Files: TRIS, TRB
  • Created Date: Nov 5 1975 12:00AM