The stress-strain behaviour of granular soils under
monotonic and cyclic loading conditions and small lateral
strains was studied in this work. A simple cubic triaxial
apparatus (SCTA), originally developed at Leeds University for monotonic stress-strain studies of sand under controlled
and small lateral strains, was used in this investigation.
The three principal stresses and strains can be independentLy controlled and measured in this apparatus. The
SCTA was modified and further developed to allow cyclic
stress-strain studies of granular soils-to be performed.
To increase the stress-strain data available on
granular soils similar tests to those previously carried out
on the medium sand, were performed on fine and coarse
sands under monotonic loading conditions. The samples tested
were cubic of 150 mm side length and prepared with ranges of
initial porosities in a dry condition.
To study the cyclic stress-strain behaviour of sand at
small strains, a series of new tests on similar cubic
samples of the medium sand were performed under cyclic
loading conditions. Cyclic loads with different frequencies,
amplitudes and number of cycles were applied and the
samples were prepared dry at the loosest and densest
conditions.
Values of the coefficients of active pressure, earth
pressure at rest, constrained secant modulus, Young's
modulus and Poisson's ratio for the fine, medium and coarse
sands were obtained and compared for different conditions.
The relationships between vertical and lateral stresses are
found and the volume change behaviour of sands in different
conditions are studied. Finally some comparisons are made
between the results obtained from monotonic and cyclic
loading conditions.