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About Us: NEES @ UC Davis
Center for Geotechnical Modeling

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THE NEES GEOTECHNICAL CENTRIFUGE FACILITY AT DAVIS

The centerpiece of the University of California, Davis NEES site is a 9-m, 75 g geotechnical centrifuge that is used for static and dynamic testing of soil and soil-structure models. Geotechnical centrifuges enable realistic physical modeling of the nonlinear static and dynamic responses of soil and soil-structure systems (see Principles of Centrifuge Modeling).

The UC Davis centrifuge has the largest radius and platform area of any geotechnical centrifuge in the US and is among the largest in the world. The centrifuge can carry 5 ton payloads to 75 g at its effective radius of 8.5 m. The large size and available resources allow researchers to perform experiments of complete geotechnical engineering systems with a level of detail and complexity that is not possible with smaller scale centrifuges.

NEES enhancements to the facility capitalized on the size of the centrifuge and revolutions in instrumentation and information technology to enable generation of higher resolution information (control, sensors, and images) and more realistic physical models, providing unique experimental data for assessing Model Based Simulation theories. The centrifuge is a shared-use facility in the NEES laboratory. Researchers are invited to take advantage of the centrifuge facilities and centrifuge test data available at UC Davis.

The shaking table mounted on the centrifuge is used to simulate ground motions comparable to those from micro-tremors to great earthquakes, in either biaxial (horizontal-vertical) or uniaxial (horizontal) shaking modes.

A high-speed data acquisition system records data from up to hundreds of sensors in a single test. Dense sensor arrays can be used to study the spatial patterns of wave propagation, the diffusion of excess pore pressures generated by earthquake shaking, or to quantify the internal deformations of the soil profile at resolutions that were previously impossible.

Other capabilities include: high-speed video cameras that can be used to image the surface of models and track deformations during shaking events; bender element arrays that can be used to measure shear-wave velocity distributions; and an electrical resistivity tomography system that can create images of internal resistivity distributions that can be correlated to porosity distributions. The various independent systems are interconnected in the data acquisition network. The network structure can accommodate future growth or custom data acquisition systems developed on a project-specific basis. A new 470 square meter building houses the visualization and control room, where we use 3-D software and our Geowall stereo display to explore data from hundreds of sensors collected in simulated earthquake events. The room is also outfitted with video conferencing and telecollaboration equipment so that remote researchers can interact with local staff during experiments.

The UC Davis NEES Operations team currently consists of - PI: Ross Boulanger (Center Director) and Co-PI: Dan Wilson (Associate Director). Past Directors of the Center for Geotechnical Modeling include Professors Jim Cheney (Founding Director 1977-1989), I. M. Idriss (1989-1996), and Bruce L. Kutter (1996-2009).