Automated 3-D analysis of Gravity Dam stability
- Computer Aided Engineering Associates, Woodbury, CT (United States)
The safety and stability of nonfederal hydroelectric project dams in the U.S. is a responsibility of the Federal Energy Regulatory Commission (FERC). FERC requires dam owners to reevaluate their structure`s stability every five years. In spite of the fact that FERC guidelines allow owners to use a variety of analytical approaches, millions of dollars are spent each year on safety modifications based on sometimes very conservative analysis methods. Analysis methods are often limited to hand calculations that assume a 2-D rigid body bending response of the dam or automated 2-D finite element analyses which can sometimes predict smaller safety factors than the rigid body analyses. Evaluation of dam stability using 3-D finite element analyses can sometimes reduce the conservatism in evaluating a dam`s stability even when conventional wisdom suggests that a 2-D analysis is sufficient. Significant increases in stability obtained from the 3-D analyses come primarily from the confining stresses from the dam abutments and the redistribution of load along the dam`s length. Even when the confining stresses are relatively small, large changes in sliding safety factors can be seen, since most dams, stability is extremely sensitive to variations in dam-rock interface cracks. The confining stresses reduce the propagation of cracks. The length of crack controls the magnitude of uplift loads applied to the bottom of the dam which in turn potentially leads to longer crack lengths. Both crack length and magnitude of uplift load directly effect the sliding stability factor of safety.
- OSTI ID:
- 220153
- Report Number(s):
- CONF-9507190--
- Country of Publication:
- United States
- Language:
- English
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