1 NEES-Pile: Experimental and Computational Study of Pile Foundations Subjected to Liquefaction-Induced Lateral Spreading Topic for Wrap-up Discussion Day 2: Current/Future Research and Other Project Activities Rensselaer Polytechnic Institute August 20 th, 2007

2 Wrap-up discussion Proposed set-up for new 1g laminar box: –Keep 2D feature with no external restriction but wider for better stability, and with appropriate protective measures (stoppers). –We propose a 6x6x6 box. It would be comparable in size with NIED E- Defense 8x8x5 box, but with capability for inclining it. –We propose to keep the concept of modular rings. This will serve several purposes. It is especially important for lateral spreading tests. In lateral spreading tests, the box would be wider and/or shorter for 2D tests, and longer and taller for 1D tests (adding lateral support).

3 Wrap-up discussion 1-g Pile Tests: –Start with flexible pile (low EI) instead of rigid pile, so as to have less boundary effects. Test will be similar to free field SG-1 test. –Keep angle 2 degrees. Build on understanding how this sand behave at 2 degree angle in free field. –Keep same non-destructive shaking and same transition cycles to compare with SG1, that is, keep same first 8.5 sec of SG1. –After 8.5 sec, continue with the originally planned input? Shortened version of original input? Implement appropriate protective measures: automatic actuators system stopper and physical stoppers for the box. –Explore possibility of FEM pile lateral spreading run(s) at UCSD simulating 1g Test 1B (low EI), so as to predict lateral displacement, pinning effect, etc. –Pile group tests? To be decide after results of high EI single pile test. Will also depend on dimensions of new laminar box.

4 Wrap-up discussion 1-g Pile Tests: –All SAA were lost, but they are part of the recovery cost budget. Four new SAA will have the right height and higher sampling rate. Possibility exists of buying more than 4 depending on needs of SI research at RPI. –Appropriate target will be installed on each ring, and North camera either has capability to increase frame rate over 30 frames/sec, or it may be replaced by a high speed camera with a higher frame rate: equal or larger than 100 frames/sec? Price of such camera about 3-5K. –Possible use of tactile pressure sensors to measure lateral soil pressure at pile near the surface. This could be challenging in terms of submerging and sealing this sensor.

5 Wrap-up discussion Centrifuge Pile Tests: –Marcelo’s Sept pile centrifuge test with reduced particle size and water shows dramatically the importance of compressibility. Compressibility coefficient m v (c v = k / (m v x  w )) seems to play a role as important as the permeability in terms of compressive/dilative response, formation of shear bands near pile, etc. The following laboratory and centrifuge tests should be considered: –Consolidation test with Buffalo sand at a void ratio of e = and similar hydraulic fill deposition method to get m v and compare it with Marcelo’s m v of reduced particle size at same void ratio used in Sept centrifuge test. (Theva/Raghu) –Explore repeating centrifuge test of SG-1 with a pile, using reduced particle size and void ratio that will give us compressible soil. Will we get same Vs profile as in Buffalo (Vs1 of about 90 m/sec?) Will we get now same free field response in the centrifuge? Will we get rebound of the pile and pile response qualitatively similar to what we expect in 1g pile test? (Gonzalez)

6 Wrap-up discussion DEM simulation: –We will try to have a “working DEM-Pile model” within this year (2007) (Dessaleng/Zeghal) –Once we have a “working DEM-Pile model” the following ideas will be considered for the first production run: (i) inclined deposit; (ii) base shaking; (iii) try to increase D pile /D 50 from 6 to something close to centrifuge tests (D pile /D 50 ~ 50?); and (iv) try to create a more compressible soil deposit by either artificially creating a looser deposit (using Medina’s unsaturated soil model?) or using non-spherical particles (clumping particle together) (Dessaleng/Zeghal) –Free field DEM runs should aim to: (i) try to match centrifuge as well as 1g SG-1 test; (ii) create base lines for pile runs. (El Shamy)

7 Wrap-up discussion FEM simulation: –Proposed meeting at RPI by end of September. (Elgamal meeting with RPI group.) –New graduate student working at UCSD in FEM-Pile simulations: Jose Ramirez. –Jose is close to replicating Liangcai He pile-runs of NIED 1g test, and getting ready to make parametric study with the existing FEM-Pile model used by He. –Parametric study with FEM-Pile model, will include variation of soil permeability. In addition, and after recent discussions in Workshop, parametric variation in soil compressibility will also be considered, although this is computationally more challenging.

8 Wrap-up discussion 3D Viewer: –New features: (i) Supports multiple open models; (ii) model editor; (iii) open files directly from NEES Central; and (iv) new simpler file format –New capabilities ready by end September 2007: (i) profile plots; (ii) sensor legends; and (iii) sensor orientation. –Future “possible” capabilities: (i) cross plotting stress-strain loops; (ii) coupling 3D-Viewer and GSI (Elmekati’s SI program)?; (iii) movie capability???