Impact of structural cracks on the stability and failure behaviour of concrete buttress dams

While cracks are commonly found in concrete dams, their potential impact on failure modes is not yet fully understood. Since cracks may compromise safety, this study investigates their effect on dam stability. The failure behaviour of a concrete buttress dam was examined using physical model tests, conventional analytical methods, and finite element (FE) simulations. The dam monolith was studied intact and with two typical crack types: a thermal crack and a toe crack. A thermal crack altered the failure mechanism, causing internal sliding along the crack, while a toe crack had no effect. Overturning only occurred when the toe was removed and sliding restrained, suggesting that this mode is unlikely unless the toe is severely degraded. The analytical Shear Friction Method (SFM) and Limit Equilibrium Method (LEM) predicted failure loads only in simple cases. In contrast, FE simulations captured failure loads and modes across all configurations. An alternative analytical method was proposed, combining rigid-body mechanics with the SFM, which improved the predictions where the other methods failed. These findings highlight limitations in conventional analytical tools and demonstrate the value of FE simulations and refined analytical approaches for dam stability assessment.