Back-calculating strength parameters and predicting displacements of deep-seated sliding surface comprising weathered rocks

A cost- and time-effective procedure for back-calculating the strength and deformation properties of natural slopes consisting of highly weathered or jointed rocks is of high practical importance. A novel procedure is proposed which incorporates a limit-equilibrium-based slice method to derive strength parameters for soils and weathered rocks and a force-equilibrium-based finite displacement method (FFDM) to derive the displacement-related material parameters for a deep-seated sliding mass. Various failure criteria for soils and rocks are used in back-calculating the strength parameters for a studied slope. First, the displacement-related parameters are back-calculated based on the measured slope displacement triggered by an intensive rainfall. These back-calculated strength and displacement parameters are then used to predict slope displacements induced by subsequent events of rainfall. The effectiveness of the proposed procedure is verified based on the case history of a natural slope subjected to periodic rainfall-induced slope movements.