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Saturation of sand specimens during experimental investigations is important to correctly reproduce undrained shearing behavior, including liquefaction. Sand below the water table is often well saturated in situ because any gases trapped during deposition or compaction have had adequate time to dissolve or migrate through the sand. Reproducing this condition on a short time scale in the laboratory often requires use of backpressure or vacuum saturation. However, backpressure and vacuum saturation sometimes cannot be utilized, for example, in centrifuge models containing soils sensitive to the effects of vacuum. This paper focuses on development and validation of a water pluviation device to construct saturated sand levees during a centrifuge testing program for which backpressure and vacuum methods could not be utilized. P-wave velocity, Vp, measurements using an ultrasound system verified the degree of saturation achieved in the fill. Correlations between Vp and B values are discussed. The vacuum saturation system is shown to provide a high degree of saturation (Vp > 1500 m/s), whereas more traditional water pluviation techniques are shown to produce unsaturated fill.

Four large-scale centrifuge tests were performed at the NEES@UCDavis equipment site to study the cyclic behavior of levee structures resting atop soft organic peat. The model configurations using a non-liquefiable levee focused on the seismic deformation potential of peat during primary consolidation and secondary compression. The tests performed with a sandy levee studied the liquefaction potential of saturated loose sand fill overlying soft peat as well as the levee-peat-interaction under different loading conditions. The models were subjected to scaled ground motions representative of the Sacramento/San Joaquin Delta. System instrumentation consisted of linear potentiometers, pore pressure sensors and accelerometers. Slow data recorded at 1 Hz document the settlements during spin up, application of ground motions, and spin down. Fast data sampled at 4,167 Hz measured the dynamic response of the system, the excess pore pressure increase and immediate settlements. The project is archived at the NEES data repository under nees.org/warehouse/project/1161 .