Effects of Rock Foundation Roughness on the Sliding Stability of Concrete Gravity Dams Based on Topographic Surveys

Abstract

This paper investigates the effects of rock foundation roughness on the shear strength of dam–rock interfaces and dam sliding stability. For this purpose, bathymetric and light detection and ranging (LiDAR) surveys of existing rock foundation surfaces were carried out close to existing dam sites and processed to obtain realistic dam–rock interface geometries differing by their roughness. The generated rock profiles are implemented into nonlinear finite-element models to conduct stability analyses of two gravity dams differing by size. A detailed analysis of the nonlinear response of dam–rock interfaces is presented in terms of limit friction angles, sliding safety factors, dilation angles, apertures, dam displacements, and shear stresses. It is shown that global roughness along dam–rock interfaces can substantially increase their shear strength. Natural local shear keys at a dam–rock interface may greatly improve the sliding stability of gravity dams; however, their effect is found to be sensitive to dam size and rock mechanical properties. Roughness effects on shear strength are found to generally decrease for larger dams. The results also reveal that the influence of rock strength parameters is more significant when the rock foundation surface includes prominent natural shear keys.