The effect of seismic preshaking history on the liquefaction resistance of granular soil deposits

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Authors
El-Sekelly, Waleed E.
Issue Date
2014-12
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Electronic thesis
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ENG
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Civil engineering
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The research incorporated data from both the field, and centrifuge and full-scale experiments. State of the art tools and sensors were used in the tests in order to capture as precisely as possible the response of the soil and connect it to the field. The work included three centrifuge tests performed at RPI (Experiment 1-3) and a full scale test performed at University at Buffalo, UB (Experiment 4). The tests simulated the effect of several decades to several centuries of earthquake events on a 5-6 m uniform clean or silty sand horizontal deposit, including both events that liquefied the deposit and others that did not liquefy it. The experimental program involved testing different shaking sequences, in order to explore the complex relation in the field between preshaking seismic events that increase the liquefaction resistance of young deposits, and liquefying events that may decrease it totally or partially. Different shaking sequences were applied in the four experiments. However, all deposits were subjected to three or four basic event types: Events A, B and C (or D). An Event A was defined as 5 sinusoidal cycles of a peak base acceleration, apb ≈ 0.035-0.045 g; an Event B was defined as 15 sinusoidal cycles of a peak base acceleration, apb ≈ 0.04-0.05 g; and an Event C (or D) was defined as 15 sinusoidal cycles of a peak base acceleration, apb ≈ 0.1-0.25 g, all in prototype units. The prototype frequency in all cases was 2 Hz. The 15-cycle duration of Events B, C and D corresponds approximately to an earthquake of moment magnitude, Mw ≈ 7.5; while the 5-cycle duration of the Events A correspond to Mw ≈ 6. An Event A represents a mild to moderate earthquake shaking; an Event B represents a mildly strong earthquake shaking; and an Event C (or D) represents a strong to very strong extensive liquefaction shaking in the field.
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December 2014
School of Engineering
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Rensselaer Polytechnic Institute, Troy, NY
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