Centrifuge test RNK01 on prefabricated vertical drains for liquefaction remediation

This is the second test in a series of three dynamic centrifuge tests designed to evaluate the effectiveness of prefabricated vertical drains in mitigating liquefaction. Centrifuge testing was performed using the 9-m radius centrifuge at the NEES@UCDavis Center for Geotechnical Modeling. The centrifuge model consisted of sloping ground with liquefiable sand overlain by a low-permeability crust. Water was used as the pore fluid. A centrifugal acceleration of 15g was applied.

The centrifuge model featured two mildly sloping (3 degree) soil profiles separated by a central channel. The soil profiles consisted of a drain-treated area and an untreated area with non-draining tubes. Each slope was comprised of a 4 to 5 m thick (prototype scale) layer of liquefiable sand overlain by a 1 m thick (prototype scale) clay cap.

The model was subjected to 18 shaking events. The first shaking event was a 0.05 g step wave. The next 15 shaking events were earthquake motions ranging in PGA from 0.018 to 0.88 g. Two earthquake acceleration-time histories were used for these input motions. These input motions are outcrop motions recorded during the 1994 Northridge earthquake (PAC175) and the 1974 San Fernando earthquake (PSL180). Finally, two sine wave input motions with 20 cycles of motion at a frequency of 2 Hz (prototype scale) with PGAs of 0.26 g and 0.56 g were applied to the model.

***Final data report - now available at the 'documentation' tab.***