Our paper on  ” Strains and Pore Pressures Generated during Cyclic Loading of Embankments on organic Soil”, published in the September 2017 issue of ASCE JGGE was selected as Editor’s Choice paper. Please find the paper here. Thanks Prof. Gabr and the JGGE editorial board!


The seismic response of a stiff levee structure placed on soft peat foundation soil is studied using centrifuge testing. The model levee was 5.1 m tall in prototype dimensions and rested atop 6.1 m of peat. The model was shaken with a suite of earthquake ground motions scaled to various intensities. Vertical and horizontal displacement records obtained from accelerometer arrays embedded in the peat were interpreted using bilinear quadrilateral interpolation to obtain in-plane components of the Cauchy strain tensor at each time increment. A direct-simple-shear-equivalent shear strain invariant, γ DSS,eq  was computed from the tensors. Values of γ DSS,eq  as high as 7% were observed for input accelerations of 0.52g 0.52g . Residual excess pore pressures were mobilized at shear strain amplitudes higher than 1%, reaching maximum residual pore pressure ratios near 0.2. The observed relationship between the residual excess pore pressure ratio and mobilized shear strain agrees reasonably well with results from a laboratory simple shear testing program. Vertical strains in the levee toe region were 2.5 times larger than beneath the crest attributable to levee rocking under seismic loading. These vertical strains contribute to γ DSS,eq   and therefore constitute an important demand on the underlying peat.

I had the great opportunity to join the GEER M7.1 Mexico earthquake reconnaissance team to assess Mexico City and surrounding areas. A few photos of our trip are posted in the Gallery section. Be sure to download the preliminary and final reconnaissance reports from the GEER website (here). Thank you Prof. Juan Villa & Students from UNAM for hosting us and investigating the City and neighboring regions with us. Despite the destruction and damage it was amazing to witness the  resilient spirit of the locals, the sense of community and belonging, and the help and support network. Joyful hearts (especially among the kids) in spite of the disaster. Interesting engineering observations, particularly relating to site effects and the effect on structure and infrastructure damage can be found in the report. It was fun to use the UAVs to explore less accessible areas – and seeing the Mexican kids full of fascination about the “flying machines”, as they put it. It was wonderful to make new friends and work alongside long time friends.



I am very proud of two of my students to secure high reward, competitive fellowships for their outstanding intellectual achievements and promising future as young researchers. Susana won the (18k) Henri Samueli Fellowship, and Lohrasb was awarded the prestigious, nationally competitive EERI-FEMA Fellowship award (12k). The one-year EERI  FEMA fellowship, underwritten with funds provided by the Federal Emergency Management Agency, is designed to foster the participation of capable individuals in working toward goals and activities of the National Earthquake Hazards Reduction Program. Both students work in earthquake engineering research within the structural and geotechnical area, respectively.