Deformation Analysis of Ritschard Dam: A Case Study of Rockfill Compression Induced Movements

Ritschard Dam was constructed from August 1993 to September 1995 by the Colorado River Water Conservation District. The dam is 125 feet high zoned embankment with a relatively thin clay core, downstream filters and drains, and rockfill shells composed of terrace gravels, shale, and clay. Changes to the design occurred as a result of conditions encountered during construction resulted in localized variability and reduced stiffness in the rockfill shell material. Since construction, the dam has experienced settlement of approximately 2.3 feet (approximately 1.8% of the dam height) and translation in the downstream direction of approximately 1.0 feet as measured at the dam crest. Deformation modeling was performed using the FLAC finite difference program to simulate the historic deformations of the dam and provide a tool that could be used to evaluate the mechanism for the movement and assess the performance implications of the deformations.