Shaking Table Experiments to Evaluate the Boundary Effects on Seismic Response of Saturated and Dry Sands in Level Ground Condition

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The laminar shear boxes (LSBs) are commonly preferred for geotechnical physical modeling over the fixed wall boxes; the latter may suffer from problems associated with wave reflection. This paper mainly describes the seismic response of a uniform layer of loose saturated and dry sands in rigid and flexible boundary conditions. A lightweight LSB was recently designed and fabricated by the authors for physical modeling of geotechnical earthquake engineering problems. To investigate the boundary effect on the seismic response of level ground, a series of shaking table tests were conducted with both LSB and rigid wall containers in identical conditions. The seismic performance of the free-field ground in the experiments is evaluated in terms of time histories, shear stress–strain hysteresis loop, and dynamic soil properties. The dynamic movements of all layers in the LSB, captured by image processing techniques, are compared with that of the rigid end-wall condition. The results demonstrate that acceleration and settlement of the ground surface are highly affected by artificial boundaries in both dry and saturated sands. It is shown that the hysteresis loops estimated from the LSB tests are more compatible with the cyclic behavior of sands, compared with those of the rigid box tests.