Saturated shear strength behavior of granitic residual soil grade VI / Noraida Mohd Saim … [et al.]

Tropical residual soils are widespread in Malaysia due to its location in a hot and humid tropical region. More than 75%
of the land area in Peninsular Malaysia is occupied by residual soil that formed by the weathering process of granitic,
sedimentary and metasedimentary (metamorphic) rocks. Since the feature of tropical residual soil is prominent in
engineering construction work such as highway cut-slopes, dam site excavations and is also widely used as construction
fill materials for highway embankments, earth dam, and fill-platforms for housing development, the properties and the
behavior of the residual soils needs to be investigated The main difficulty of the residual soils is associated with rainfall
distribution and the effect of the infiltration of the surface run off on the earth. This is due to the slope failure cases on
residual soil in the tropics are triggered by the infiltration of the surface run off that occurs during heavy rainstorm
that caused damages and deaths. In this study, the shear strength characteristics of residual soil were assessed using
consolidated drained (CD) triaxial tests for saturated soil specimens. Curve Surface Shear Strength Envelope Model
(CSSEM) was used to interpret the test results. The test results shows that the failure envelope forms a non-linear shape
at low stress levels that shows the soils exhibits drop in shear strength as effective stress approaches zero in saturated
specimens. This is mean that shear strength vanished drastically as the soil gets closer to the ground surface and when it
is wetted by the infiltrated water. Furthermore the application of Curve Surface Shear Strength Envelope Model (CSSEM)
is useful to avoid the problem of overestimating and under estimating of shear strength behavior.