Location

San Diego, California

Session Start Date

5-24-2010

Session End Date

5-29-2010

Abstract

The effect of earthquakes on the behavior of soil and/or structures is usually investigated using earthquake-like signals as input for loading. This holds true for most of numerical and experimental simulations. In contrast to those approaches sinusoidal excitation was used here. The benefit of this type of excitation is an increased observability of the system, which is a precondition for a systematic investigation. Since sinusoidal excitation allows a gradually, step by step increase of the applied loading, the state of the soil (density and effective stress) as well as pore water pressure are transient. Therefore they are varying slowly and the modes of vibration are changing with time accordingly. The modes can be identified by regarding the contour of a soil column for instance. The evolution and distribution of pore water pressure (up to liquefaction) has to be captured simultaneously. A further advantage of this method is that asymptotic behavior can be investigated for the evolutions of pore water pressure and settlement of the surface with an increasing number of cycles. On the base of a numerical study some test in a shake-box will be shown using the described concept. Numerical modeling of soil behavior under cyclic respectively dynamic loading requires the application of nonlinear constitutive laws. With the used FE-model it is possible to observe the dependence of excitation amplitude, frequency and initial state on the transient amplification of the sinusoidal input signal up to an onset of liquefaction. The appropriate experimental investigations confirm the numerically observed behavior. Therefore a shake-box under 1-g conditions with smooth boundaries is used for the tests. They were performed with a homogeneous soil column (about 0.8m length, 0.6m width, 2.1m height) from medium-grained quartz sand under saturated conditions.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fifth Conference

Publisher

Missouri University of Science and Technology

Publication Date

5-24-2010

Document Version

Final Version

Rights

© 2010 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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May 24th, 12:00 AM May 29th, 12:00 AM

Numerical and Experimental Investigation of Soil Behaviour Under Stationary Excitation

San Diego, California

The effect of earthquakes on the behavior of soil and/or structures is usually investigated using earthquake-like signals as input for loading. This holds true for most of numerical and experimental simulations. In contrast to those approaches sinusoidal excitation was used here. The benefit of this type of excitation is an increased observability of the system, which is a precondition for a systematic investigation. Since sinusoidal excitation allows a gradually, step by step increase of the applied loading, the state of the soil (density and effective stress) as well as pore water pressure are transient. Therefore they are varying slowly and the modes of vibration are changing with time accordingly. The modes can be identified by regarding the contour of a soil column for instance. The evolution and distribution of pore water pressure (up to liquefaction) has to be captured simultaneously. A further advantage of this method is that asymptotic behavior can be investigated for the evolutions of pore water pressure and settlement of the surface with an increasing number of cycles. On the base of a numerical study some test in a shake-box will be shown using the described concept. Numerical modeling of soil behavior under cyclic respectively dynamic loading requires the application of nonlinear constitutive laws. With the used FE-model it is possible to observe the dependence of excitation amplitude, frequency and initial state on the transient amplification of the sinusoidal input signal up to an onset of liquefaction. The appropriate experimental investigations confirm the numerically observed behavior. Therefore a shake-box under 1-g conditions with smooth boundaries is used for the tests. They were performed with a homogeneous soil column (about 0.8m length, 0.6m width, 2.1m height) from medium-grained quartz sand under saturated conditions.