INFLUENCE OF MATRIC SUCTION ON INSTABILITY OF UNSATURATED SILTY SOIL IN UNCONFINED CONDITIONS
Keywords:
Slope failure, Water infiltration, Suction, Shear strength, UnconfinedAbstract
Rainfall has been recognized as one of the main causes of natural or manmade slope failure in
many tropical areas of the world. In order to reduce and mitigate rainfall-induced slope failures, there is a need
to develop an understanding of reduction in shear strength of soil due to water infiltration. This research aimed
at understanding the influence of matric suction on water infiltration and transformation of shear strength in
unsaturated soil in unconfined condition. In the present study, two types of test series have been performed
using modern triaxial test apparatus: (1) shear-infiltration test, and (2) pre-wetting shear test. From test results,
it was concluded that water infiltration causes the excessive deformations and softening which decreases the
cohesion and hence reduces the shear strength of the soil. The more decrease in shear strength was witnessed
in case of pre-wetting shear tests and maximum reduction observed was 85% against 36cm3 of infiltrated water.