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Rensselaer Polytechnic Institute August 20 th , 2007

NEES-Pile: Experimental and Computational Study of Pile Foundations Subjected to Liquefaction-Induced Lateral Spreading Topic for Wrap-up Discussion Day 1: Free field tests LG-0 and SG-1. Rensselaer Polytechnic Institute August 20 th , 2007. Wrap-up discussion.

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Rensselaer Polytechnic Institute August 20 th , 2007

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  1. NEES-Pile: Experimental and Computational Study of Pile Foundations Subjected to Liquefaction-Induced Lateral SpreadingTopic for Wrap-up DiscussionDay 1: Free field tests LG-0 and SG-1 Rensselaer Polytechnic Institute August 20th, 2007

  2. Wrap-up discussion • Submission of internal reports for analysis of test SG1 (Nov 1st, 2007) and 3D Viewer (Nov 1st, 2007). 4 reports (Co’PIs) + 1 report mechanics lateral spreading (Raghu, Medina, Bennett). DEM, FEM + Centrifuge group: combine report on LG-0 and SG1 • If we are going to publish different papers and refer them between each other. Shouldn’t we go with the same units and time scale? International system and t = 0 to 8.5 sec • Which kind of sand are we dealing with? Contractive? Dilative? Get Theva’s PDF’s with results of triaxial tests and steady-state properties of sand (it will be sent to the whole group). New triaxial tests at Buffalo using wet pluviation (Theva). Take advantage of tests to be done by Vucetic? (Dobry)

  3. Wrap-up discussion • Data suggest lateral spreading begins when soil is not yet fully liquefied. New way to describe liquefaction and lateral spreading in terms of micromechanics approach? Coordination number? Relation to dilative response? (include in DEM and lateral mechanism reports) • From displacement data there are “2 CLEAR” events of sliding when driving force is minimum (max positive acceleration). Can we predict at which specific depth(s) will sliding happen? Is it related to the time of sliding initiation and hence to type of shaking input? Why does sliding start at time t is minimum? (to be included in lateral mechanism report)

  4. Wrap-up discussion • Issue of tflow/s’vo = 0.08 depending to the slope of the box and not on soil properties? Different if we change the inclination of the box? • Compute plots of tf = Sr vs time at different elevations or sliding planes (include in lateral mechanism reports) • Include appropriate target in each ring for future tests at Buffalo. Install potentiometers in each ring if possible • Different Vs profile for Centrifuge and 1g test. Also, large amplification NDS in Buffalo (frequency close to resonance?). Therefore more acceleration input has been needed in centrifuge tests. We need: • Study dynamic amplification effects in both SG-1 and centrifuge in NDS. Shake, FEM? To predict output (Gonzalez and Raghu in reports) • Repeat centrifuge simulation of SG-1 with wet pluviated sand? To be decided after seeing results of new triaxial tests at Buffalo

  5. Wrap-up discussion • Repeat SI of centrifuge and SG-1 for Vs, making sure we are consistent, including inertia of rings above ground surface (Gonzalez) • Repeat DEM run of SG-1 with 2 degrees and seepage parallel to slope. Objective: try to get a “working DEM model” of SG-1 (El Shamy) • Repeat FEM runs of SG-1 and LG-0 until we have “working FEM model” of SG-1 and LG-0 (Medina and Elgamal)

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