Hydraulic fracturing is defined as the formation of cracks in soil by the application of hydraulic pressure greater than the minor principal stress at that point. At present, it is believed that the pressure at which a crack not opens but closes in a decreasing pressure situation more nearly defines the minor principal stress across the crack. As the crack closes there is an abrupt change in flow since there will be no flow in the crack & the permeability of the soil governs. This method eliminates two variables associated with the crack opening process: (1) outward movement of the soil before cracking, and (2) irregular flow from the source and in the crack. One other important variable, loading history, affects both methods of determining the ratio of horizontal to vertical effective stress, K sub o, for design. For an overconsolidated condition, the minor principal stress would approximate the vertical (overburden) stress instead of the lateral stress, thereby negating obtaining a K sub o ratio. There is evidence that there is disagreement of values obtained by different methods (conventional laboratory, pressuremeter, vane shear, etc.) of determining minor stresses and it is suggested that fracturing is just another tool that helps to define a range of values. While there are reservations concerning hydraulic fracturing as a means for determination of lateral stresses, the technique can still be used for determining in situ total stress and permeability at a point in a cohesive soil.

  • Availability:
  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    3909 Halls Ferry Road
    Vicksburg, MS  United States  39180-6199
  • Authors:
    • Leach, R E
  • Publication Date: 1977-3

Media Info

  • Features: Appendices; Figures; References;
  • Pagination: 26 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00153348
  • Record Type: Publication
  • ISBN: CWIS 31173
  • Report/Paper Numbers: Miscel Paper S-77-6 Final Rpt.
  • Files: TRIS
  • Created Date: Aug 15 1977 12:00AM