Rapid drawdown in embankment dams

Abstract

The work presented in this chapter focuses on the third group of movements: slides that move on a shearing surface with a relatively light degradation of the mobilized body.1.1 Reservoir level and landslide riskReservoir operation implies two unfavourable effects for the stability of banks and slopes:a. The submergence of the toe of a potential landslideb. The rapid drawdown conditionRegarding the first point, considerer a slope partially submerged. The groundwater profile will be affected by the position of the reservoir water1 INTRODUCTIONIn the design, construction and operation of dams and reservoir sites, instabilities of banks and ancient landslides by reservoir impoundment are one of most important issues to face. Most of dams and reservoirs are located in natural valleys frequently resulting from fluvial or glacial erosion whose banks are potentially unstable. There is a risk that engineering projects activate or reactivate landslides. In addition, it is common to find valleys whose geologic structure is a syncline involving stratification layers parallel or subparallel to the topographic slope. This situation favours the motion of landslides into reservoirs. In these cases, potential sliding planes are generally located in layers, faults or shearing zones that exhibit smaller shear strength than the surrounding strata.