Embankment Dam on Liquefiable Foundation-Dynamic Behavior and Densification Remediation

Earthquake-induced liquefaction is a major concern for embankment dam safety. Many liquefaction-induced earth embankment failures or near failures have been reported around the world during various earthquakes. Such embankment damages were particularly destructive when the underlying saturated granular soils liquefied, resulting in cracking, settlement, lateral spreading, and slumping of the embankment. Through a series of four highly instrumented geotechnical centrifuge model tests, seismic behavior of a zoned embankment dam with saturated sandy soil foundation was studied under moderate earthquake conditions. The beneficial effects of foundation densification were investigated. Valuable insights into the dynamic behavior of the employed embankment-foundation systems are provided. Test results suggest that there may be an optimum depth of densification treatment beneath an earth dam beyond which the reduction of the earthquake-induced deformations are relatively minor and that relatively small and isolated zones (e.g., at depth) of loose material within a densified volume of soil may not impair the overall effectiveness of treatment and do not necessarily result in damaging displacements.