Challenges in Assessing a Hydraulic Fill Dam Built in the 1920s for Liquefaction and Piping Potential

ABSTRACT: The unsatisfactory performance of the hydraulic fill dams in seismically active areas is well known. Hydraulic fill placement technique usually results in loose fills that are susceptible to liquefaction under earthquake loading. Hydraulic fill placement technique was used during the original construction of a dam built in the 1920s in Alberta, Canada. This dam is partially founded on alluvium, which may also be prone to liquefaction. The earthfill embankments have zonation with core, transition zones and shells but without any filter zones or clear boundaries between the zones because of the hydraulic fill placement technique used during construction. The variable material composition and grain size from fine-grained to gravel make the assessment of liquefaction difficult as appropriate and multiple in-situ testing techniques and laboratory testing are required to assess their liquefaction potential. The absence of well-defined engineered filters and the variable grain size of the dam fills and foundation materials make the dam prone to internal erosion and piping also. This paper presents the challenges in assessing the liquefaction and piping potential of the hydraulic fill dam.