Influence of Matric Suction on Short Term Stability Analysis of Unsaturated Slopes


Short term stability analysis of slopes and embankments made up of fine grained soils are often carried out based on undrained shear strength determined from laboratory unconfined compressive test. In an unconfined compression test, it is primarily assumed that the test is conducted on a fully saturated soil specimen under undrained conditionIt is generally seen that the usual water content in field is below the shrinkage limit of the soil; hence the soil is not always fully saturated. This causes a deviation in the results obtained from unconfined compression test where friction angle is assumed zero. The deviation is caused by the phenomena of suction pressure or matrix suction. Thus, the shear strength now depends upon two stress variables, one is normal stress and other is the matrix suction. In this study, interpretation of matrix suction theory is applied to unconfined compression test to study the safety of slopes.

In International Conference on Sustainable Civil Infrastructure, Hyderabad, India pp.437-442