Numerical analysis of liquefaction-induced lateral spreading phenomenon and investigation of the effect of ground slope and liquefiable soil thickness on lateral displacement

Omid Ghasemi Fare, 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: Lateral spreading of liquefied granular soils induces large displacements and because of that it is one of the destructive phenomena which causes great damages to the buildings, roads, pipelines, and piles. Maximum ground displacement most necessary parameters for seismic design of earthworks and foundations, so this paper focuses upon these parameters. In this paper after validating numerical simulation with experimental observation, the verified model is used for parametric study. For parametric study the ground surface inclination and thickness of the liquefiable soil are selected as variable parameters and their effects on maximum lateral displacements which occurs at the ground surface are investigated. This study shows that ground surface inclination is a very important parameter on lateral displacement, its increase leads to increase in the amount of lateral displacement; however the amount of normalized lateral displacement is independent of the value of ground surface inclination.

RÉSUMÉ: La propagation latérale des sols granulaires liquéfiés induit de grands déplacements et en raison de celle elle est l'un des phénomènes destructifs qui endommage grands les bâtiments, les routes, les canalisations, et les piles. Le déplacement au sol maximum et c'est variation par rapport à la profondeur sont les paramètres les plus nécessaires pour la conception séismique des terrassements et des bases, ainsi foyers de ce document sur ces paramètres. En ce document après validation de la simulation numérique avec l'observation expérimentale, le modèle vérifié est employé pour l'étude paramétrique. Pour l'étude paramétrique l'inclination et l'épaisseur extérieures au sol du sol liquéfiable sont choisies en tant que paramètres variables et leurs effets sur des déplacements latéraux maximum qui se produit sur la surface au sol sont étudiés. Cette étude prouve que l'inclination extérieure au sol est un paramètre très important sur le déplacement latéral, son augmentation mène pour augmenter dans la quantité de déplacement latéral ; cependant la quantité de déplacement latéral normal est indépendant de la valeur de l'inclination extérieure au sol. 1. INTRODUCTION The lateral movement of a liquefiable soil layer on gently slopes is the most visible and devastating type of liquefaction-induced ground failure. Occurrence of liquefaction in sloping grounds causes large deformations on ground surface, which may reach to several meters in some cases (Wang & Rahman 1999). Recent earthquakes have shown that this phenomenon causes severe damages to coastal structures, piers of bridges and life-lines, by exerting large lateral forces. Due to the significance of these failures during liquefaction, a number of research activities have been done in various categories such as physical tests, sliding block analysis, artificial neural networks, and numerical simulation. In the group of physical research, a wide range of centrifuge and shaking table tests have been employed. One of the most comprehensive and well-known experimental studies tests in this field is the laboratory tests conducted on Nevada sand by the Earth Technology Corporation in the course of Verification of Liquefaction Analysis by Centrifuge Studies (VELACS). Besides, Taboada and Dobry (1995), and Sharp and Dobry (1999) had investigated the effects of the important parameters on lateral displacement with experiments conducted at Rensselaer Institute of Technology. Also some researches like Cubrinovskiet al (2005) and Bethapudi (2008) simulated lateral spreading phenomenon by shaking table tests. Empirical methods utilize ground inclination and liquefiable ground layer thickness as the fundamental parameters that affect the amount of lateral displacement using regression data analysis. The amount of surface ground movement can be estimated with these formulas easily. Hamada et al (1986-1999), Bardet et al (1999), Youd et al (2003), and Valsamis et al (2010) proposed different relations based on data obtained from field observations. In addition to this, various numerical methods have been employed to simulate lateral spreading phenomenon. Here, some numerical studies are briefly explained: Uzuoka et al (1998) predicted the lateral spreading of liquefied subsoil based on fluid dynamics; they simplified the behaviour of liquefied soil with Bingham model, which is a model for viscous fluids. In this model shear stress has a linear relation with shear strain. Also, Hadush et al (2000) used similar methods for

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