Discontinuous hydromechanical modelling of concrete dam foundations

Abstract

The analysis of the hydromechanical behaviour of concrete dam foundations requires coupled models which account for the role of deformation in fluid flow and the stability of the rock mass. In this study the hydromechanical analysis is performed by means of an explicit time stepping small displacement algorithm, Parmac3D-Fflow, based on a discrete representation of the discontinuities. In order to evaluate the practical importance of stress-sensitive fluid flow in rock mass discontinuities a case study is presented of an arch-gravity dam, 83 m high. Especial attention is given to boundary conditions, drainage system simulation and sets of mechanical and hydraulic parameters that may control flow and stress behavior. This paper presents the results of the application of a 3D discontinuum hydromechanical model for the analysis of the behaviour of the dam foundation. In this hydromechanical model the hydraulic behaviour is simulated assuming that seepage takes place along channels located at the edges of the triangular interface elements which simulate the various discontinuities. In the study presented here the main emphasis is on the simulation of the drainage system and on the results of sliding stability analysis. Conclusions are drawn regarding the safety factors obtained using the traditional method of strength reduction and other methods in which the hydrostatic load is gradually increased.