Dynamic centrifuge testing of a temporary braced excavation in dry sand

Today, most of the world's population lives in cities, where subway systems offer a sustainable means of public transportation. In many cases, underground transportation infrastructure is built near tall buildings with multistory basements. Although such buildings have the potential to alter ground motions in their vicinity and transmit forces to adjacent underground structures during earthquakes, these impacts are not well understood. Centrifuge testing combined with nonlinear numerical analyses are being employed to evaluate the seismic performance of interacting soil, structure, and underground structure systems. Two initial, baseline centrifuge tests involved permanent and temporary cut-and-cover box structures with no adjacent building present. This paper summarizes the planning and design of the baseline experiment on the seismic response of a temporary braced excavation (Test-2). An overview of the test setup, model construction, and instrumentation layout is provided, followed by a brief discussion of preliminary test results in terms of accelerations, racking deformations, and lateral earth pressures on the model structure during a series of broadband earthquake shaking events.