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CEE Seminar - An Alternative Approach to Dynamic Earth Pressure Coefficients to Improve the Seismic Limit State Design of Earth Retaining Structures

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Friday, February 09, 2024
12:00 pm - 1:00 pm
Dr. Srikanth Madabhushi, Associate Professor, Geotechnical Engineering & Geomechanics, University of Colorado Boulder
CEE Spring Seminar Series 2024

Dynamic earth pressure coefficients are widely used in the seismic engineering design of earth retaining structures. Nevertheless, there remains confusion about their validity, with past studies conflictingly arguing that the same estimates can be either conservative or un-conservative. In this seminar, a combination of centrifuge and numerical modeling is used to explore the dynamic response of simple and complex earth retaining systems.

The complex case of dual row retaining walls is initially studied to investigate their potential use as tsunami defence against multi-hazard events, e.g., combined earthquake and tsunami loading and liquefaction of the foundation soil. The combination of dynamic centrifuge modeling and numerical analyses informed the different mechanisms governing the dynamic response when the system was founded in dry and liquefiable soils. Insights made into the dynamic response of the retained soil highlighted the importance of soil rocking under horizontal shaking. This hinted at a solution to the past confusion surrounding the seismic limit state of retained soil.

A simpler case of a level bed of retained soil is used to generalize the findings from the dual row walls. The combination of dynamic centrifuge modeling and numerical analyses exposes the importance of dynamic normal vertical effective stresses. This allows for a more fundamental interpretation of the limiting dynamic stress state of geomaterials. Finally, simplified analytical methods to estimate the limiting distribution and time histories of stresses in retained soil are proposed. Validation of these against the numerical predictions illustrates a path forward to estimate the limiting horizontal stresses, and thus forces, for the improved seismic limit state design of earth retaining structures.

Contact: Nicolle Hinz