This concrete dam built in the 1940s includes a gated spillway section, powerhouse, and nonoverflow sections in the center of the dam with zoned fill embankment on the left and right sides of the concrete structures. Concrete core walls were constructed in the embankment wrap around areas to provide seepage control. Early in the service life of the facilty settlement in retaining walls on the crest and downstream rotational movement of the concrete core walls were observed. Retaining wall settlements on the order of several feet and core wall deformations on the order of 5 inches in the downstream direction were recorded. The objective of the project was to identify and fill data gaps related to dam performance, develop comprehensive models of the structures, identify causal mechanisms, and perform a field investigation to evaluate the conditions contributing to deformations and the current state of the dam related to risk driving Potential Failure Modes (PFMs)
Geosyntec’s Scope of Services
Geosyntec conducted an issue evaluation study (IES) for four risk-driving PFMs associated with the concrete/embankment wraparound sections of the dam. Geosyntec gathered data from the client’s libraries and the National Archives for research, analysis, and data gap evaluation. A soil structure interaction model in PLAXIS 2D and 3D was performed to investigate the causal mechanisms of observed lateral displacements of the core wall and settlements of the retaining wall. Additionally, an engineering analysis and calculation packages were completed summarizing the main findings.
Our team performed a causal evaluation and performance review to identify causal mechanisms that may have triggered the deformations and developed a comprehensive field investigation program to address project data gaps and inform the risk assessment.
Based on the evaluation study, engineering analysis, and results of numerical modeling, Geosyntec is performing a comprehensive field investigation to evaluate dam safety relative to the risk-driving PFMs in the next phase of the IES.
- Location: United States
- Client: Confidential
- Project Practice Areas: Environmental Management
- Services Provided: Issue Evaluation Study; Archival Records Review; Comprehensive Records Database; Potential Failure Modes Analysis; 2D & 3D Soil Structure Interaction Model; Facilitation of Technical Workshops; Engineering Analysis; Comprehensive Field Investigation Plan