Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles

Extensive damage to buildings and infrastructure observed during past earthquakes resulting from the liquefaction of shallow saturated soil deposits underneath structures has demonstrated necessity for further research in area liquefaction-induced ground movement effects. This study explores utilizing helical piles as a countermeasure reduce foundation settlement investigates their seismic performance liquefiable grounds. Two large-scale shake table test series, one without any mitigation measures using piles, were conducted facility at University California, San Diego. During each superstructure models extensively instrumented subjected two consistently applied shaking sequences. The model included layer aimed replicating subsurface conditions New Zealand, Japan, Turkey. Liquefaction-induced mechanisms are broadly categorized follows: (1) shear-induced, (2) volumetric-induced, (3) ejecta-induced. In first series (referred Baseline hereafter), all these three components realistically reproduced, while second Helical Pile hereafter) volumetric ejecta-induced mainly mitigated, significant reductions settlement. Results (i.e., test) indicated that flow velocity due hydraulic transient gradient displayed an upward loose layer, which explains sand ejecta. tests resulted average total 28 cm 42.7 measured settlements compared estimated obtained Liu Dobry [1997] Bray Macedo’s [2017] simplified procedures. generally higher than values. identical setup was used except group four attached mitigate settlements. this tests, reduced excess pore-water pressure generation around is attributed increased relative density zone influence result installation. supported on underwent almost no differential tilt. A reduction achieved series. project experimental reproduced key mentioned above including effects sediment ejecta, have not been captured prior studies. addition, provides unique benchmark calibration numerical procedures reliably estimate building Although introduced reliable highly efficient measure tilt settlement, proper design nd application areas still need thorough investigation possible amplified response.