S.n. Moghaddas Tafreshi, A. Asakereh,
Volume 5, Issue 4 (December 2007)
Abstract
Conventional investigations on the behavior of reinforced and unreinforced soils are often
investigated at the failure point. In this paper, a new concept of comparison of the behavior of
reinforced and unreinforced soil by estimating the strength and strength ratio (deviatoric stress of
reinforced sample to unreinforced sample) at various strain levels is proposed. A comprehensive set
of laboratory triaxial compression tests was carried out on wet (natural water content) non-plastic
beach silty sand with and without geotextile. The layer configurations used are one, two, three and
four horizontal reinforcing layers in a triaxial test sample. The influences of the number of
geotextile layers and confining pressure at 3%, 6%, 9%, 12% and 15% of the imposed strain levels
on sample were studied and described. The results show that the trend and magnitude of strength
ratio is different for various strain level. It implies that using failure strength from peak point or
strength corresponding to the axial-strain approximately 15% to evaluate the enhancement of
strength or strength ratio due to reinforcement may cause hazard and uncertainty in practical
design. Hence, it is necessary to consider the strength of reinforced sample compared with
unreinforced sample at the imposed strain level. Only one type of soil and one type of geotextile
were used in all tests.
A. Asakereh, S.n. Moghaddas Tafreshi, M. Ghazavi,
Volume 10, Issue 2 (June 2012)
Abstract
This paper describes a series of laboratory model tests on strip footings supported on unreinforced and geogrid-reinforced sand
with an inside void. The footing is subjected to a combination of static and cyclic loading. The influence of various parameters
including the embedment depth of the void, the number of reinforcement layers, and the amplitude of cyclic load were studied.
The results show that the footing settlement due to repeated loading increased when the void existed in the failure zone of the
footing and decreased with increasing the void vertical distance from the footing bottom and with increasing the reinforcement
layers beneath the footing. For a specified amplitude of repeated load, the footing settlement is comparable for reinforced sand,
thicker soil layer over the void and much improved the settlement of unreinforced sand without void. In general, the results
indicate that, the reinforced soil-footing system with sufficient geogride-reinforcement and void embedment depth behaves much
stiffer and thus carries greater loading with lower settlement compared with unreinforced soil in the absent of void and can
eliminate the adverse effect of the void on the footing behavior. The final footing settlement under repeated cyclic loading becomes
about 4 times with respect to the footing settlement under static loading at the same magnitude of load applied.
