Deformation Analysis for Seismic Retrofit of an Embankment Dam

Success Dam located in Southern California is seismically deficient and remediation design is currently in progress. The proposed remediation includes partial excavation of the existing embankment dam and construction of a buttressing embankment immediately downstream. Liquefiable alluvium will remain under the existing dam and will continue to affect the seismic response of the combined structure. In accordance with Corps of Engineers guidance, the design must be validated using a seismic deformation analysis. The deformation analysis was performed in steps of increasing complexity, starting with simplified procedures and continuing with more complex, state-of-the-art methods: (1) liquefaction assessment using the simplified procedure and QUAD4M coupled with limit equilibrium analyses assuming post-liquefaction residual strength in potentially liquefiable zones; (2) FLAC computer analysis using the decoupled effective stress constitutive model used by URS, and (3) FLAC analysis with the coupled effective stress model UBCSAND developed at the University of British Columbia, Canada.