DESIGNING CRITICAL FOUNDATIONS ON SAND AND GRAVEL

The development of soil mechanics has left soils such as deep sand and gravel sequences (that underlie many waterfront sites) to be evaluated on the basis of what are only improved empiricisms. The relevant properties of intergranular soils depend solely on particular intergranular relationships within the deposit. The relative excellence of the intergranular arrangement within any deposit of cohesionless granular material can be expressed in terms of its relative density. When soils near the surface are in question, relative density may be determined by direct measurements in test pits or by correlation with plate bearing tests. The standard penetration test in the most commonly employed procedure for soils 10 ft or so below surface. Details are described of this in situ punching shear test. The relevant properties of granular soils are those which describe shear stength which determines ultimate beaming capacity, and some expression which will determine vertical deflection (or settlement) of the foundation under applied loads. The angle of internal friction (psi) and secant modulus of elasticity (E) are used for the purpose. A table is presented which shows the general relationships between N (number of blows required to drive standard spoon 1 ft. using 140-lb hammer falling 30 inches) and Dr (relative density). The settlement problem is dicussed in detail and a simple procedure for estimating settlements on sands and gravels in illustrated by curves developed by Terzaghi and Peck. The analytic approaches in determining settlements on sands and gravels are, almost without exception, based on analogies with elastic theory. A formula is presented which is a satisfactory expression containing all elements of the settlement problem on sands and gravel, and limitations on its use are discussed. Methods (hydraulic and nuclear) which may be used in the future are briefly considered.

  • Corporate Authors:

    Norwood Publications Limited

    Elm House, Elm Street
    London WC1X OBP,   England 
  • Authors:
    • Thorpe, W
    • Gitterman, H
  • Publication Date: 1965-10

Media Info

  • Features: Figures; References;
  • Pagination: p. 102-106
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00083793
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 29 1975 12:00AM