EFFECT OF IRREGULAR TIME-HISTORY ON THE CYCLIC RESISTANCE OF SAND

The liquefaction behaviors of sandy soils are generally investigated using stress or strain controlled dynamic tests in the laboratory.  In terms of ease and applicability of analysis, uniform loading patterns are usually preferred. However, irregular wave forms with different amplitudes and frequencies are generated throughout the soil layers during seismic excitations. In this study, a comprehensive series of cyclic tests have been performed on clean sand samples. Conventional uniform loading and ground-motion records scaled to different cyclic stress ratios were applied to identically prepared specimens. The pore pressure build-up and accumulated strain effects are investigated regarding the effect of the loading type and cyclic stress ratio. The outcome of test series aimed to provide further improvement on dynamic strength approaches for liquefaction assessment, in order to expand its use in current engineering practice.

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