Scale Model Shake Table Testing of an Underground Tunnel Cross Section in Soft Clay

Abstract

Underground structures exist in many active earthquake regions, but empirical data of the seismic behavior of these structures is very limited. This research works toward filling that empirical data gap with scale model shake table testing. Underground seismic soil-structure interaction (USSSI) effects were investigated for a stiff tunnel embedded within soft clay. Young Bay mud was used as a prototype soil for developing a scale model soil mixture. A Bay Area Rapid Transit (BART) cut-and-cover subway tunnel was used as the prototype for the one-tenth scale model subway cross section. The flexible wall test container in these tests allowed the soil to deform in simple shear. Similitude analysis scaled critical variables to properly capture prototype behavior at the model scale subjected to 1-g shake table testing. The measured horizontal “racking” distortions of the model structure compared to numerical analyses suggest that current simplified design methods may overestimate distortions in soft-soil/stiff-structure situations.

Multi-point shaking table test of the free field under non-uniform earthquake excitation

“…Based on the theory, Meymand (1998) designed the scale-model clay, which was used in the shaking table test of soil-pile-structure model. Moss and Crosariol (2013) developed model soil and model tunnel for shaking table test following the similitude theory. Iai (1989) derived a similitude relation for a 1 g shaking table test of saturated soil-structure-fluid model.…”

“…It is introduced that energy absorption material was used on boundary of rigid model boxes (Moss and Crosariol, 2013;Lombardi, et al, 2015). In this test, a number of 200-mm-thick polystyrene foam boards were stuck to inner sidewalls of all twelve model boxes.…”

Experimental Assessment of the Effect of Vertical Earthquake Motion on Underground Metro Station

“…Based on the capability of the existing facility and equipment, the similitude ratio design of the experiment was accomplished on the basis of the dimensional analysis, which was adopted extensively in the design of the shaking table tests by other researchers. Meymand [26] designed and performed a series of scale model shaking table testing of the piles in clay in a 1 g scale model environment [27], in which he summarized that the method of the governing equations involved the differential equation describing the process and the formation of the similarity variables that related the model to the prototype. The similitude ratio design for this research herein closely follows the aforementioned method.…”

Experimental Study on Seismic Response of a Large‐Span and Column‐Free Subway Station in Composite Strata

“…Che et al [8] conducted a shaking table test on buried culvert and found that the culvert was largely subjected to lateral earth pressure during an earthquake. Moss and Crosariol [9] performed a series of shaking table tests on the basis of tunnels in the Bay Area Rapid Transit System in San Francisco and compared the test results with the numerical analysis results, concluding that the existing design method overestimates the racking distortion of soft soil-rigid structures.…”