NON LINEAR FINITE ELEMENT ANALYSIS OF GRAVITY DAM SECTIONS

Abstract

The evaluation of the safety factors of old dams under higher flood levels in the last few years has been investigated under the assumptions of fracture mechanics. The extensive need for research in this field was recognized by the U. S. Army Corps of Engineers that now requires a fracture mechanics investigation prior to the rehabilitation of cracked massive concrete structures. In large structures, such as dams, because of the smaller size of the fracture process zone with respect to the structure size, limited errors should occur under the assumptions of Linear Elastic Fracture Mechanics (LEFM). But is assumed only for the sake of simplification. Fracture behaviours of concrete and other quasi-brittle material cannot be investigated under the assumptions of LEFM. Nonlinear Fracture Mechanics should be used for such type of problem. In this thesis a parametric study has been performed under the assumptions of LEFM on a triangularly shaped gravity dam having a horizontal crack at the dam / foundation interface and some approximate equations have been given for evaluating Stress Intensity Factors. Height of the dam (D), Downstream slope (m), Normalized crack length (a), E~/Ef ratio have been taken as a parameters. Finally an attempt has been made to study the fracture behaviour of concrete gravity dam under the assumptions of NLFM. Principal stress variations along the nonlinear zone (FPZ) for different softening models of concrete which, in turn, would provide a more rational basis for the design.