Asymmetric input motion for accumulation of lateral ground deformation in laminar container shake table testing

Abstract

Due to seismic response, accumulation of permanent ground deformation (lateral spreading) is an important mechanism of much practical significance. Such deformations typically occur near a ground slope, behind retaining structures such as sheet-pile and quay walls, and in mildly sloping ground. In conducting a shake table test, the generation of permanent deformations further elucidates the underlying mechanisms and allows for related ground–foundation–structure response insights. In this paper, an approach for development of accumulated ground deformations is presented, in which asymmetric inertial loading results in a biased dynamic one-dimensional shear state of stress. As such, the proposed approach allows for further insights into the soil cyclic response and pore pressure build-up, with deformations accumulating in a preferred direction. To permit a virtually unlimited number of such loading cycles, focus is placed on motions that do not cause the shake-table actuator to accumulate displacement, in view of its possible limited stroke. Using this approach, representative experimental response is outlined and discussed. This experimental response can be used for calibration of numerical models to emulate the observed permanent strain accumulation profile and associated mechanisms. In addition to liquefaction-induced lateral spreading, this asymmetric shaking approach might be beneficial for a wide class of earthquake engineering shake table testing applications.