Influence of permeability on the stability of dual-structure landslide with different deposit-bedding interface morphology: The case of the three Gorges Reservoir area, China

Abstract

The construction of the Three Gorges Reservoir (TGR) has considerably increased landslide hazard due to the 30-m annual fluctuating reservoir water level. In this study, the influence of permeability on the stability of dual-structure landslide with different deposit-bedding interface (DBI) morphology were comprehensively investigated. A landslide database including 560 recorded dual-structure landslides was built for the statistical analysis. The DBI morphology, the slope structure and the permeability were classified and presented. The statistical analysis of the DBI morphological parameters indicates that the armchair type (AT) is the most popular in over-dip landslide, the curved type (CT) is very widespread in anaclinal landslide, the stepped type (ST) is the most common DBI morphology in over-dip landslide, and the linear type (LT) could be found widely at the under-dip landslide. Two conceptual models, downslide-locked model and locked model, were proposed according to the change rules of the dip angle of the DBI. The stability for these two conceptual models were analyzed and modeled as well as verified by specific case studies. The numerical results manifest that the permeability and the DBI morphology could pose significant impacts on the stability of the dual-structure landslide. Deepening our understanding of the effect of the fluctuating reservoir water level on the factor of safety (FOS) of the defined conceptual models, which are of paramount importance to improve the design of mitigation countermeasures and, consequently, to reduce fatalities and property losses in the TGR and many other analogous reservoir areas.