Comparison of Liquefaction Triggering Analysis Approaches for an Embankment Dam and Foundation

Success Dam is located on the Tule River, near the city of Porterville, California. The dam is a rolled earth-fill embankment approximately 145 feet high and 3,400 feet long. The embankment is comprised of a central impervious core protected by upstream and downstream outer pervious zones. A majority of the dam is founded on potentially liquefiable Holocene alluvium. Several analytical techniques of varying complexity have been used to determine the liquefaction potential of the foundation Holocene alluvium and the pervious embankment shells. The following analytical techniques were used on the Success Dam Remediation Project: (1) cyclic stress ratio (CSR) evaluation using peak shear stresses obtained from QUAD4M equivalent linear seismic response type analyses, (2) evaluation of QUAD4M element shear stress time histories using a cycle counting approach to approximate the potential excess pore water pressure ratios, and (3) more advanced non-linear dynamic FLAC analyses using UBCSAND to evaluate excess pore water pressure ratios for potentially liquefiable materials. This paper discusses the approaches taken to evaluate the liquefaction potential for the seismic assessment and remediation design of the existing dam. This paper also summarizes the advantages and limitations of each of each analytical approach used to evaluate liquefaction potential of the dam and foundation materials