Investigation of the Failure Modes of Concrete Dams - Physical Model Tests

This report describes the design and testing of physical models of concrete arch dams. Two series of models are included. In the first series, a planar, two-dimensional model which represents a 1/50 scale model of the Koyna Dam in India is tested. The model is tested without water behind the dam to utilize conditions as simple as possible for comparison with numerical modeling. Cracks formed in the test are similar to cracks which resulted on the Koyna Dam following an actual earthquake event.

The second series of models are approximately 1/150 scale of a typical wide canyon dam. Material properties are adjusted to the model scale, a reservoir and foundation are included. The models utilize different joint patterns of a monolith, single horizontal and vertical joints, and multiple vertical and horizontal joints. Models are tested to collapse of the structure. Conclusions are that initial cracking of the structure is not influenced by the joints. Final collapse is a push through of sections of the dam downstream and is controlled by the joints both with the pattern of the failure and with the acceleration required to fail the structure. Water is observed as passing through the model during the loading