tion should be reconsidered in order to save aggregate
Herner, R.C. (1955) Effect of base course quality on
material. Furthermore, the Mathcad spreadsheet as
load transmission through flexible pavement. In Pro-
ceedings, Highway Research Board, p. 224-233.
shown in Appendix A can be used to calculate the stress
reduction at depth below the rectangular loads.
Mathsoft (1998) Mathcad 8 Professional. Cambridge,
More important than wheel load shape is whether
Massachusetts: MathSoft Inc.
the aggregate that is placed on top of the geotextile
McMahon, T.F., and E.J. Yoder (1960) Design of a
can be accurately modeled as a linearly elastic mate-
pressure-sensitive cell and model studies of pressure
rial, and, therefore, whether the vertical stresses are
in a flexible pavement subgrade. In Proceedings, High-
reasonably approximated by the Boussinesq method
way Research Board, 39th Annual Meeting, National
Academy of Sciences-National Research Council,
(as the current design method assumes). Indeed, stress
Washington, D.C., p. 650-682.
concentrations in sand and in clay soil compared to
Boussinesq predictions have been noted. Thus, if low
Newmark, N.M. (1935) Simplified computation of
quality aggregate composed of rounded gravel, con-
vertical pressures in elastic foundations. University of
taining sand or fines, or both, must be used in geotextile
Illinois Bulletin, 33(4).
reinforcement of low-bearing-capacity soil, this ques-
Newmark, N.M. (1942) Influence charts for compu-
tion should be addressed.
tation of stresses in elastic foundations. University of
Illinois Bulletin, 40(12).
Sowers, G.F., and A.B. Vesic (1962) Vertical stresses
LITERATURE CITED
in subgrades beneath statically loaded flexible pave-
ments. In Stress Distribution in Earth Masses. High-
Barenberg, E.J., J. Hales, and J. Dowland (1975)
way Research Board Bulletin 342, NAS-NRC, Wash-
Evaluation of soil-aggregate systems with MIRAFI
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U.S. Army and U.S. Air Force (1995) Engineering
Bowles, J.E. (1988) Foundation Analysis and Design,
use of geotextiles. TM5-818-8/AFJMAN 32-1030,
4th edition. New York: McGraw-Hill, Inc.
Headquarters, Departments of the Army and the Air
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Yoder, E.J., and M.W. Witczak (1975) Principles of
parison of two design methods for use by the U.S.
Pavement Design, 2nd edition. New York: John Wiley
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and Sons.
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