Abstract:
A new non linear approach to annlysis nnd design of unreinforced
and reinforced unpaved roads on clny subgrade is developed. These
are based on the non linear stress strain behaviour generally
exhibited by the clay subgrade soils as well as geosynthetic and
natural fibre reinforcing elements.
The newly developed design method is based on closed form
solution of the plane strain analysis of the deformation track
produced under wheel loading, which consider the compatibility of
deformation (rutting) between the constituent materials, clay
subgrade and reinforcing element.
Appropriate constitutive laws, for monotonic and repeated loading
conditions, for the subgrade clay and reinforcing elements are
developed and used to predict the behaviour under quasi-static
and traffic loading conditions. The equivalent material approach
is used to simulate the weakening of tI,e system under traffic
loading condition. Special test setup are fabricated and
installed to estnblish these COllslilutive relations.
The settlement behaviour of clay subgrade is analysed using the
fundamental approach suggested by Praknsh, Sharan and Saran
(1984), using non linear constitutive relation. The out of the
plane load deformation behaviour of reinforcing elements are
determined by assuming the deformation track to be of parabolic
shape.
Design charts are produced to show the npplicability of the new
methodology for a silty clay subgrade and a woven tape
polyethylene geotextile reinforcing element. A comparison of the
proposed method with the conventional Giroud and Noiray (1981)
method is also produced which show lhe lalter method to yield
unsafe results specially under low deformation (rutting)
conditions.
As part of developed in the research FORTRAN. a number of computer program are
