Abstract:
A simple nonlinear soil model is presented based on an initial
small strain stiffness, a yield pressure and an index 'n' that
controls nonlinearity. This model first proposed by Pender and
implemented by Carter was developed to simplify the
specification of p-y curves. Using this model a finite element
program was written by Carter based on the concept of Winkler
springs. It has been the aim of this thesis to use the computer
program to back analyse the observed behaviour of full scale field
test on lateral load behaviour of piled foundation to determine
how well the soil model presented can predict behaviour measured
in field. Results of back analysis of twenty eight piles have
shown that the soil model, although not as intricate as the p-y
curves, is able to predict the deformation characteristic with a
similar degree of accuracy.
The effect of changes in pile width on the initial small strain
stiffness is investigated. The best agreement between measured
and computed pile response is obtained using a linear relationship
between the modulus and the pile width.
Various authors have proposed a limiting reaction pressure that
can be mobilised by the soil. For cohesionless soils a limiting
pressure distribution which increases at a rate of 5KpL gave the
closest match. For cohesive soils ultimate pressures which
increases iinearly from 5s, at the surface to 12s, at depth is
most appropriate.
The versatility of the above soil model has been clearly
demonstrated in this thesis.