ARGO-E GROUP staff has co-authored a new article  published in the American Society of Civil Engineers Journal of Geotechnical and Geoenvironmental Engineering. In this publication, titled “The Role of Liquefaction on the Seismic Response of Quay Walls during the 2014 Cephalonia, Greece, Earthquakes”, Dr. George Zalachoris, and Prof. Dimitrios Zekkos (of ARGO-E GROUP and UC Berkeley) along with co-authors Prof. Adda Athanasopoulos-Zekkos (University of California at Berkeley) and Prof. Nikos Gerolymos (National Technical University of Athens) showcase a well-documented case history of liquefaction of gravelly fills, by performing fully-coupled dynamic numerical analyses of the port quay walls in the island of Cephalonia, Greece.

The ports of Lixouri and Argostoli exhibited ground cracking and coarse-grained soil ejecta as well as lateral ground displacements ranging from 0.1 to 1.5 m, as a result of the Cephalonia, Greece, 2014 earthquake sequence (M_w6.1 and M_w6.0). Three different constitutive models were used in the numerical analyses and were calibrated based on in-situ site characterization data, while the computed dynamic response of the structural systems was compared to the observed response of the quay walls, as documented by post-event reconnaissance missions.

The findings of the study are particularly insightful on the complexities of liquefied soil-structure interaction issues associated with port quay walls, as well as their response on ground motions that are affected by directivity.

The abstract of the article reads:

“Following the Cephalonia, Greece, 2014 earthquake sequence (Mw=6.1 and Mw=6.0), liquefaction of gravelly earthfill materials at the ports of Lixouri and Argostoli resulted in the manifestation of ground cracking and coarse-grained soil ejecta, while the quay walls in these ports exhibited lateral ground displacements ranging from 0.1 m to 1.5 m. To evaluate the seismic performance of the port quay walls, numerical analyses using the Finite Difference method were performed and the results are compared to the observed response. Three commonly used constitutive models (PM4Sand, UBCSand, and URS/ROTH), calibrated based on in-situ site investigation data, were considered in modeling the liquefiable earthfills. The results of the numerical analyses at both ports, using the best-estimate parameters, indicate that taller walls exhibit smaller lateral ground displacements, something that is in line with field observations. For the shorter walls, liquefaction induced lateral spreading played an important role in the observed response, while for the taller walls, the seismic behavior is dominated predominantly by the dynamic response of the structural system. PM4Sand and UBCSand models seem to yield very similar deformational results, while the URS/ROTH model, which assigns residual shear strength parameters once liquefaction is triggered, resulted in horizontal displacements that are closer to the observations for short wall geometries, but over-predict the response when the effect of liquefaction on the overall displacements is small. Finally, the numerical analyses demonstrate the strong influence of the pulse-like characteristics, as well as the polarization of the input motion on the seismic response of the Lixouri quay walls, indicating that forward directivity contributed significantly to the observed quay wall deformations.”

You can find the published journal article here!