A parametric study on seismic performance of piles embedded in two-layered liquefiable ground

Amin Rahmani, Ali Pak

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Earthquake Engineering & Geophysics

ABSTRACT: In this paper, fully coupled three-dimensional dynamic analysis is carried out to investigate the dynamic behaviour of pile foundations in liquefied ground. The critical state bounding surface elastic-plastic constitutive model, Dafalias and Manzari (2004) is used, while a fully coupled (u-P) formulation is employed to analyze soil displacements and pore water pressures. Furthermore, variation of permeability coefficient during liquefaction is taken into account. Seismic response of a single pile in liquefiable soil layers is compared with the results of a centrifuge test, and it is found that there is a good agreement between the test results and the computed data. Then, the verified model is used for a parametric study by varying pile length, thickness of liquefying soil layer, relative density of liquefying soil layer and frequency of input motion. The parametric study is carried out for a single pile embedded in a two-layered ground: the upper layer is liquefiable while the lower layer is not. In general, the parametric study demonstrates that thickness of liquefying soil layer and frequency of input motion are the most critical parameters which considerably affect pile performance in liquefied grounds. Therefore, these parameters should be of higher concern during designing pile foundations in liquefiable soil strata. R…SUM… Dans ce document, l'analyse dynamique tridimensionnelle enti‘rement coupl”e est effectu”e pour ”tudier le comportement dynamique des bases de pile en sol liqu”fi”. Le mod‘le d'”lastique-plastique ext”rieur d'”tat critique, le Dafalias et Manzari (2004) constitutifs de bondissement est employ”, et en addition, une formulation enti‘rement coupl”e est utilis”e pour analyser des d”placements de sol et des pressions d'eau interstitielle. En outre, la variation du coefficient de perm”abilit” pendant la liqu”faction est prise en consid”ration. La r”ponse s”ismique d'une pile simple dans des couches liqu”fiables de sol est compar”e aux r”sultats d'un essai de centrifugeuse, et il est possible de constater qu'il y a une bonne concordance entre les r”sultats d'essai et les donn”es calcul”es. Par la suite, le mod‘le v”rifi” est employ” pour une ”tude param”trique en variant la longueur de pile, l'”paisseur d'une couche de liqu”faction de sol, la densit” relative d'une couche de liqu”faction de sol et la fr”quence du mouvement d'entr”e. L'”tude param”trique est effectu”e pour une pile simple incorpor”e dans un sol ‹ deux couches : la couche sup”rieure est liqu”fiable alors que la couche inf”rieure ne lÕest pas. G”n”ralement l'”tude param”trique d”montre que l'”paisseur d'une couche de liqu”faction de sol et la fr”quence du mouvement d'entr”e sont les param‘tres les plus critiques qui affectent consid”rablement la performance de piles en r”gions liqu”fi”s. Par cons”quent, ces param‘tres devraient ’tre davantage consid”r”s pendant la conception des bases de pile dans les strates liqu”fiables des sols.

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Cite this article:
Amin Rahmani; Ali Pak (2011) A parametric study on seismic performance of piles embedded in two-layered liquefiable ground in GEO2011. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GEO11Paper122,author = Amin Rahmani; Ali Pak ,title = A parametric study on seismic performance of piles embedded in two-layered liquefiable ground ,year = 2011}