The effect of stress path on the deformation and consolidation of London clay
Theoretical and experimental investigations have been carried
out to study the influence of stress path on the deformation and consolidation
of over-consolidated clays - with particular emphasis on
London clay - in relation to settlement of structures. It is shown
that for a proper understanding of the deformation of a soil beneath
a foundation the soil should be tested in the laboratory under the
same set of effective stresses that it will undergo in the field and
that the influence of lateral stresses cannot be ignored.
The stresses and displacements in non-homogeneous soil media,
beneath circular and strip footings, have been calculated from
Gibson's analytical solutions. A numerical method is suggested for
determining the "immediate" (elastic) settlement of structures founded
on a medium whose modulus of elasticity varies with depth.
The influence of lateral stresses on the deformation characteristics
of undisturbed London clay has been studied from both oedometer
and triaxial tests while the stress path for one-dimensional
compression is determined from specially designed oedometers. The
effect of small pressure increments on the compressibility of London
clay is also studied in the oedometer.
The experimental results are examined in the light of their
influence on the settlement of structures and a method of settlement
analysis is proposed that takes into account the stress path
of the elements of soil beneath a foundation: comparisons are made
with the existing methods of analysis.
The pre-consolidation pressures of London clay are determined
from the stress deformation characteristics of samples loaded to
high effective stresses.