CS26A - Concurrent Session 26A: 130th Anniversary of the Bouzey Dam Failure –The Importance of Internal Uplift Pressure in Stability Design of Gravity Dams

Abstract Description: Bouzey Dam was a 74-foot-high (22.7 meters), 1720-foot-long (525 meters), stone masonry gravity dam located near Epinal, France. The construction of the dam was started in 1876 and completed in 1881. On March 14, 1884, when the water depth reached 63.6 feet (19.4 meters), a large section of the dam slid up to one foot (0.35 meters) downstream. Even though this incident should have raised concerns for the owner and engineers, no serious actions were taken to mitigate the issue. In fact, the reservoir depth was further increased to 64.3 feet (19.6 meters) and the dam was kept in service for 18 months in this condition. Between 1885 and 1889, the dam was drained to facilitate repair of the structure including sealing of the upstream base of the dam, construction of a downstream embankment berm, adding foundation drains at the base of the dam, and filling vertical cracks with cement mortar/grout. Refilling of the reservoir began in 1889, and by May 1890, the water depth reached 70.9 feet (21.6 meters) and remained around the same level for the subsequent years.

On Saturday, April 27, 1895, at 5:45 AM, a 591-foot-long (180 meters) by 33-foot-high (10 meters) section of the dam collapsed. The resulting flood killed 85 people and caused extensive downstream damage. Key factors contributing to the failure included poor design and poor construction practices. Over time, horizontal cracks formed approximately 33 feet (10 meters) below the reservoir level, and full internal uplift pressure developed within the body of the dam leading to sudden overturning failure.

This presentation will discuss the lessons learned from the poor design and construction practices that led to the development and extension of cracking, the importance of considering internal uplift pressure in design of gravity dams, and the overturning failure mechanism with a focus on the failure of Bouzey Dam. We will also discuss the significance of this specific case study as it relates to major improvements in subsequent design of gravity dams including: 1) tension shouldn’t be allowed to develop at any horizontal section of the dam under usual load case, 2) the middle-third rule should be considered in the design, 3) a concrete compressive strength should not be exceeded, 4) sliding stability criteria should be met, and 5) construction techniques and quality of materials should be improved.