Browsing by Author "Patel, R.M."

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A Study on the Seismic Behaviour of Embankments with Pile Supports and Basal Geogrid
(Springer, 2020) Patel, R.M.; Jayalekshmi, B.R.; Shivashankar, R.
For constructing the roads on soft grounds, basal geogrid-reinforced pile-supported embankments are a suitable solution over other conventional ground improvement techniques like preloading, embankment slope flattening, removing and replacing the soft soil, etc. Many studies are available on these basal geogrid-reinforced piled embankments to understand their behaviour under static loading conditions. But it is necessary to understand the behaviour of these geogrid-reinforced piled embankments under seismic excitations. Hence, finite element analysis of three-dimensional models of embankment having crest width of 20 m, height above ground of 6 m, with side slopes of 1V:1.5H consisting of pulverized fuel ash, overlying soft marine clay of 28 m thickness is carried out under seismic excitations corresponding to Zone III (IS:1893). Soft marine clay layer is improved by the addition of piles arranged in square grid pattern with 5.75% area replacement ratio. Geogrid with a tensile modulus of 4600 kN/m is used as the basal reinforcement. Initially, the embankment is analyzed without geogrid reinforcement and pile supports. Then, it is analyzed with (i) Basal geogrid (ii) With pile supports (iii) With basal geogrid and pile supports. The influence of various parameters of the embankment on maximum crest displacements, differential settlements at crest, toe horizontal displacements, stresses at pile head and foundation soil between piles and pile bending moment along the depth at peak acceleration are studied. Analysis of results shows that the embankment supported over piles with basal geogrid reinforcement will experience less crest settlements, differential settlements at crest and toe horizontal displacements due to earthquake load. © 2020, Springer Nature Singapore Pte Ltd.
Effect of Reinforcement Width on Dynamic response of Basal Geosynthetic-Reinforced Embankment
(Springer, 2022) Patel, R.M.; Jayalekshmi, B.R.; Shivashankar, R.
High compressibility and poor shear strength properties of soft clayey foundation soils are problems to be dealt with in the design and construction of embankments or roads. The inclusion of geosynthetic at the embankment base is one of the ground improvement techniques used to construct roads or embankments over soft clayey subsoils. This article aims to present the seismic behaviour of basal geosynthetic-reinforced embankments, and various parameters are analysed to identify the suitable width of basal geogrid using time-history analysis. Embankments of heights 4 to 10 m with varying side slope angles are studied. Analysis of results shows that the addition of basal geogrid not only improves the stability of the embankment under static loading conditions but also improves the seismic performance of the embankment. From the results of this study, it is found that the basal geogrid reinforcement of a total width equal to the embankment base width plus embankment height and with a high tensile modulus of 4000 kN/m is required to effectively withstand the seismic forces in seismic regions with peak ground accelerations up to 0.6 g. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Response Variation of Body-Reinforced Embankments Subjected to Seismic Load
(Springer Science and Business Media Deutschland GmbH, 2024) Patel, R.M.; Jayalekshmi, B.R.; Shivashankar, R.
At places where the land restrictions exist, the construction of embankments with flat side slope is an issue. During such circumstances, the embankment side slopes were steepened by providing the geosynthetic reinforcements to the embankment body. The stability of these body-reinforced embankments under static loading conditions is well explained in the literature. Though there are studies on their seismic behaviour, the analysis of these embankments supported on different foundation soils and provision of very steep slopes under seismic loading need to be studied. An attempt is made in this article to study the effect of embankment side slope and foundation soil property by performing the numerical analysis of body-reinforced embankments subjected to seismic excitations. The embankment body is reinforced with six layers of geogrid having 500Â kN/m tensile stiffness with 1Â m vertical spacing along the embankment elevation on both sides of the embankment slope. The crest centre accelerations, face lateral displacements and crest vertical displacements are observed. The analysis of results indicates that, though the reinforcements are provided at the side slope and not extended throughout the embankment body, the addition of reinforcement could reduce more than 80% of the lateral displacements at crest centre. The reduction of face horizontal displacements due to the inclusion of reinforcement is much effective in steep slopes than in shallow slopes. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Seismic Response of Basal Geogrid Reinforced Embankments Supported on a Group of Vertical and Batter Piles
(Springer Science and Business Media Deutschland GmbH, 2021) Patel, R.M.; Jayalekshmi, B.R.; Shivashankar, R.; Surya, N.R.
Basal geogrid reinforced embankments supported on vertical piles are proven to be a feasible and effective solution for constructing embankments over thick soft clay deposits and bridge approaching embankments. These solutions minimize the lateral displacements, total and differential settlements of embankment crest and toe by transmitting embankment loads into the deeper stratum through pile foundations and arching action of geogrid. Basal geogrid reinforcements provide good restraint against lateral spreading of the toe. Providing batter piles near the toe will further enhance this restraint against lateral spreading. Not many studies are available in literature on performance of batter piles below embankment toe, especially under seismic excitations. The present study aims to find the advantages of providing batter piles below embankment toe under seismic excitations. A 6Â m high basal geogrid reinforced embankment having 1Â V:1.5H side slope constructed over 28Â m thick soft clay is considered for the 3-Dimensional finite element analysis. The soft clay is stabilized with 22Â m long 300Â mm diameter vertical and batter piles spaced at three times the pile diameter. Embankment crest vertical displacements, toe horizontal displacements, maximum differential settlements at the crest and crest lateral accelerations are analysed for different batter angles of 0Â°, 5Â°, 10Â°, 15Â°. Analysis of results reveals that larger the batter angle more is the reduction of toe horizontal displacements. Â© 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Stress Distribution in Basal Geogrid Reinforced Pile-Supported Embankments Under Seismic Loads
(Springer, 2021) Patel, R.M.; Jayalekshmi, B.R.; Shivashankar, R.
Basal geosynthetic reinforced pile-supported embankments are proven as the more appropriate ground improvement technique for constructing embankments for roads over very soft clay deposits and approach roads or embankments to bridges. Numerous experimental and analytical works are available on the soil arching phenomenon of geosynthetic reinforced piled embankments subjected to static loading conditions. This study attempts to evaluate the stress distribution and soil arching in geosynthetic reinforced pile-supported embankments subjected to seismic excitations. Time-history analysis has been performed on the basal geogrid reinforced pile-supported embankments by varying the height of embankment and tensile modulus of geogrid. Analyses of results show that for ? (the ratio of height of embankment to pile centre to centre spacing) less than or equal to 4.5, a geogrid tensile modulus of 3000 kN/m is sufficient to withstand vertical stresses due to earthquakes. And for the considered embankment height and pile diameter when ? nearly equal to 4.5, differential settlements are very less irrespective of seismic excitations. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.