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dynamic behavior of sand with nanoparticles

Dynamic Behavior of Sand with NanoParticles Comportement dynamique de Sable avec Nanoparticules Felipe Ochoa-Cornejo Civil Engineering Department University of Chile Chile fochoa ing uchile cl ABSTRACT This work presents an experimental investigation to examine the e ?ect of Laponite -a synthetic nanoclay with high plasticity- on the dynamic behavior of sands The experimental program considers cyclic triaxial and resonant column tests on specimens of pluviated sand and Laponite Microstructure observation address the granular fabric and the sand- Laponite interactions Cyclic triaxial tests show that of Laponite impacts the cyclic behavior improving the liquefaction resistance over one order of magnitude compared to clean sands Resonant column tests show that the small strain sti ?ness of the sand G increases with of Laponite The overall results show that Laponite extends the linear threshold of deformation reduces sti ?ness degradation and delays excess pore pressures Microstructure observations suggest that Laponite reduces sand particle mobility by the formation of a pore uid with solid-like properties RÉSUMÉ Ce travail présente une étude expérimentale pour examiner l'e ?et de la Laponite -une nanoargille synthétique avec une plasticité élevée- sur le comportement dynamique des sables Le programme expérimental envisage des essais triaxiaux cycliques et de colonne résonnante sur des échantillons de sable pluvié et de Laponite L'observation de la microstructure concerne le tissu granulaire et les interactions sable-Laponite Les essais triaxiaux cycliques montrent que de Laponite a ?ecte le comportement cyclique améliorant la résistance à la liquéfaction sur un ordre de grandeur par rapport aux sables propres Les essais de colonnes résonantes montrent que la rigidité à faible déformation du sable G augmente de plus de avec de Laponite Les résultats globaux montrent que la Laponite prolonge le seuil linéaire de déformation réduit la dégradation de la rigidité et retarde les pressions de pores en excès Les observations de microstructures suggèrent que la Laponite réduit la mobilité des particules de sable par la formation d'un uide poreux à propriétés solides KEYWORDS Nanoparticles Liquefaction Cyclic Triaxial Tests Resonant Column Tests Microstructure INTRODUCTION Liquefaction is a large-strain phenomenon occurring in saturated loose sand deposits during earthquakes causing large ground deformations and signi ?cant damage to civil and industrial infrastructure Ochoa-Cornejo et al Youd et al Liquefaction occurs as cyclic shear induces particle mobility as undrained conditions prevail during earthquakes excess pore water pressures generate decreasing the e ?ective stresses with each cycle of loading Eventually a transient condition of zero e ?ective stress is reached initiating liquefaction large deformations and ground failure Castro Ishihara Liquefaction and its catastrophic damage were ?rst observed in in the Alaska and Niigata Earthquakes both of magnitude higher than Mw Youd causing settlement and collapse of urban industrial structures on saturated loose sand deposits Liquefaction has also been observed in earthquakes such as El Maule Christchurch and Tohoku Bhattacharya et al Bradley Verdugo Liquefaction research initially focused on clean sands and the factors controlling the behavior and resistance of sands against this phenomenon Castro and Poulos Seed and Lee Seed et al These studies