Groundwater-table-induced slope displacement analyses using different failure criteria

A force-equilibrium-based finite displacement method (FFDM) incorporating Mohr-Coulomb (M-C) and Hoek-Brown (H-B) failure criteria is used to compute displacements of a monitored slope undergoing rainfall-induced groundwater table (GWT) fluctuations. The analytical method consists of back-calculating strength and displacement parameters using recorded displacements and groundwater table (GWT) in the 1st event of a series of rainfall-induced GWT changes and predicting slope displacements for other events of GWT changes. Results of analyses for the studied slope indicate that (1) despite various sets of back-calculated strength and displacement parameters are obtained, the accuracy of slope displacement prediction is not affected by using various sets of back-calculated parameters; (2) the accuracy of slope displacement prediction is not affected by the use of different failure criteria (M-C or H-B). To simulate a sliding with variable displacements along the slip surface, a displacement diagram associated with an operational dilatancy angle (ψ) is used, i.e., a negative value of ψ is selected to approximate a sliding mass undergoing a volume contraction. Results of a comparative study preliminarily shows good agreement between the calculated and the measured displacements of the slope. However, further validation for this technique using more observed data are necessary.