Determination of Residual Shear Strength from Reversal Direct Shear test: Analysis and Recommendation

Reversal Direct Shear test is used for the determination of residual strength of soil sample. This test was conducted on the undisturbed and remolded sample of embankment slope of Pa Bon Dam, Thailand that had failed after its operation for 10 years. The undisturbed sample was taken from the downstream slope (non-failure zone) while the remolded sample was taken from the upstream slope (failure zone). The results yielded the identical values of residual strength parameters. On the basis of laboratory test, various recommendations are proposed for the conduction of this test in future.