Faculty Publications

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Author: search.filters.author.Bhasi, A.Subject: search.filters.subject.geosynthetics

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    Numerical study of basal reinforced embankments supported on floating/end bearing piles considering pile-soil interaction
    (Elsevier Ltd, 2015) Bhasi, A.; Rajagopal, K.
    Construction sites consisting of soft soils may require ground improvement to prevent excessive settlements or bearing capacity type failures and shear movements, which results in construction delays and premature failures. Among the various ground improvement techniques, the Geosynthetic Reinforced Piled Embankment Systems (GRPES) provide a practical and efficient solution due to the low cost and short construction times. Most of the piled embankments are constructed on end bearing piles. At large depths of foundation soil, floating piles are more economical and technically feasible than the end bearing piles. The design of floating piles involves complex soil-structure interaction and there are no clear uniform guidelines available for the design of embankments supported on floating piles. This paper presents the results of numerical investigation into the performance of geosynthetic reinforced embankments supported on end bearing as well as floating piles considering the pile-soil and geosynthetic-soil interaction. 3-D Column models are employed to carry out the parametric studies on factors such as the development of arching, skin friction distribution along the pile length and axial force distribution. Full three-dimensional analyses are carried out to study the overall behavior of the GRPES system and the results obtained from the analyses were compared with those from British Standard BS8006-2010. The results indicated that the use of floating piles could considerably reduce the settlements and the embankment load transferred through the piles to the foundation soil is found to depend very much on the length of the piles. This aspect needs to be accounted for while calculating the arching factor in the empirical equations. © 2015 Elsevier Ltd.
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    Three dimensional analyses of geocell reinforced encased stone column supported embankments on lithomargic clay
    (Taylor and Francis Ltd., 2023) Vibhoosha, M.P.; Bhasi, A.; Nayak, S.
    Geocells are a superior form of reinforcement due to their cost-effectiveness and three-dimensional confining properties. However, numerical modeling of geocell is always challenging due to its three-dimensional honeycomb structure. The limitations of the equivalent composite approach (ECA) led to the recent development of full 3D numerical models, which consider geocell-infill material interaction. This paper discusses the time-dependent performance of geocell-reinforced encased stone column-supported embankment considering the actual 3D nature of geocells using the finite element program ABAQUS. Parametric studies were carried out to study the stress transfer mechanism, vertical deformation of the foundation soil, and stress-strain variation inside the geocell pockets. It is found from the analyses that with the provision of a geocell layer on top of Geosynthetic Encased Stone Columns (GESC), the stress concentration ratio improved by 47% at the end of consolidation compared to GESC alone. Also, an 80% reduction in foundation surface settlement is observed with geocell-sand mattresses. The geocell-sand mattress decreased the bulging of the stone columns, and almost 80% of the stone column bulging occurred by the end of the embankment construction. The proposed model’s numerical results show that the equivalent composite approach overestimated the stress concentration ratio and bearing capacity. The tensile stresses are non-uniformly distributed in the geocell pockets, and the maximum tensile force was mobilised at the geocell mid-height. Among the various geocell infill materials analysed, the aggregates were best suited considering the stress concentration ratio and vertical settlement. The numerical results supported the idea that encased stone columns with geocells at the embankment base can perform similarly to a geosynthetic reinforced piled embankment system, which is costlier but very efficient. When the modular ratio is more than 40, geocell-reinforced encased stone column-supported embankment is similar to GRPES. © 2022 Informa UK Limited, trading as Taylor & Francis Group.