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Author: search.filters.author.George, V.Subject: search.filters.subject.Soils

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Now showing 1 - 6 of 6
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    Effect of soil parameters on dynamic cone penetration indices of laterite sub-grade soils from India
    (2009) George, V.; Nageshwar Rao, Ch.; Shivashankar, R.
    The focus of this study was on correlating the effect of grain-size, maximum dry-density (MDD), field moisture content, and the void ratios on penetration measured using the dynamic cone penetrometer (DCP) for laterite soils blended with fines. Tests were performed on soil samples compacted to MDD for moulding water contents set to the optimum moisture content (OMC), dry of OMC, and wet of OMC un-soaked condition. The results indicated that an increase in the fines-content caused a decrease in the MDD, and an increase in the OMC and the DCP penetration. Regressions were developed correlating various parameters. © Springer Science+Business Media B.V. 2008.
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    Effects of soil parameters and moisture content on stiffness of unsaturated blended laterite using tri-axial tests for rural roads
    (2011) George, V.; Nageshwar Rao, C.; Shivashankar, R.
    Evaluation of subgrade strength and stiffness is essential in the design of pavements and construction of embankments for highways in order to ensure that roads perform their functions satisfactorily over a longer period. The grain size distribution and compaction moisture-content have an immense influence on the strength and stiffness of subgrades. Among the various laboratory tests for evaluation of shear strength parameters, and the modulus of elasticity of subgrades, the tri-axial test plays a major role in describing the geotechnical characteristics of the subgrade. This paper deals with an experimental investigation on unsaturated laterite soils blended with varying percentages of fines. It focuses on a study of the influence of various soil parameters on the stiffness and strength of soil samples compacted at optimum moisture content (OMC), at the drier side of OMC, and also at the wetter side of OMC, and the development of meaningful correlations. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.
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    A model study on accelerated consolidation of coir reinforced laterite and blended shedi soil with vertical sand drains for pavement foundations
    (2012) George, V.; Santosh, G.; Hegde, R.N.; Durga Prashanth, L.; Gotamey, D.; Ravi Sankar, A.U.
    Sub-grade soils of lateritic origin are frequently encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. Coir is a natural fiber that can be used in place of geosynthetics and geogrids, and it is biodegradable and environment friendly. This work deals with the accelerated consolidation of un-reinforced and coir-reinforced laterite and blended lithomargic soils, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50kg (0.0013 N/mm2) to 500kg (0.013N/mm2) using circular ferro-cement moulds. It was observed that at lower preloads up to 300kg, the relative increase in consolidation (Cr) for randomly reinforced soil with vertical drains was significantly higher than that of un-reinforced soil without vertical drains. Also, the Cr for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with values above 38.71%. However, in the case of higher preloads of 450kg and 500kg, the Cr for randomly reinforced soil with vertical drains was insignificant, and the Cr for un-reinforced soil with vertical drains remained slightly higher at around 9.59% for similar comparisons. The aspect-ratio of coir fibers used was 1: 275. © 2012 Cafet-Innova Technical Society. All rights reserved.
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    Accelerated consolidation of coir reinforced lithomargic laterite soil blends with vertical sand drains for pavements
    (2012) George, V.; Hegde, R.N.; Vardhana, M.V.; Santosh, G.; Gotamey, D.
    It is found that sub-grade soils of lateritic origin encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. This work deals with the accelerated consolidation of un-reinforced and coir-reinforced laterite and blended lithomargic soils, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50kg (0.0013 N/mm2) to 500kg (0.013N/mm2). Studies were performed using circular ferro-cement moulds. It was observed that at lower preloads of up to 250kg, the relative increase in consolidation (Rct) for randomly reinforced soil with vertical drains was significantly higher than that of un-reinforced soil without vertical drains. Also, the Rct for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with an average value of 20.84%. In the case of higher preloads the Rct values for randomly reinforced soil with vertical drains were moderate with an average value of 22.67%. An additional increase of up to 27% at lower pre-loads and 11.83% at higher pre-loads was observed due to the effect of random reinforcement when compared to use of vertical drains alone. © 2012 ejge.
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    Establishing relationships for strength characteristics of lateritic soils with varying silt fractions
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Kumar, A.; George, V.; Marathe, S.
    Design and construction of highway embankments constitute a major component of highway engineering science. Poor sub-grade strength, overloading due to traffic loads, and seismic vibrations can cause distress to pavement sub-grades and embankments. Inadequate compaction and poor sub soil drainage, in addition to low bearing strength of soils cause failure of embankments especially in submersible regions. The present study is focused on performing investigations on the engineering properties of lateritic and lithomargic soils and the effect of fines on soil strength. Tests such as California Bearing Ratio (CBR), tests for unconfined compressive strength (UCS), and tri-axial tests are carried to study the strength behavior of soil on addition of lithomargic soils. Additionally, the development of regressions will help field engineers in estimating the value of the CBR based on simple laboratory experiments such as Unconfined Compression strength test, and the Triaxial test. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Effect of Soil Parameters on Resilient Modulus Using Cyclic Tri-Axial Tests on Lateritic Subgrade Soils from Dakshina Kannada, India
    (Springer International Publishing, 2018) Kumar, A.; George, V.
    Resilient modulus (Mr) of a soil is used as a basic input in the analysis of sub-grade and sub-base in the mechanistic empirical design approaches. The present work focuses on evolving a cost effective approach for the determination of resilient modulus in the laboratory based on tests performed using the CBR method, and the DCP. Lateritic sub-grades in India exhibit wide-ranging variations in strength and stiffness due to varying fines content, and other characteristics. Additionally, soils of lateritic origin with a higher proportion of fines, also called as lithomargic soils, pose difficulties to pavement engineers due to the poor supporting strength. In order to investigate the strength and stiffness of a wide variety of lateritic soils, it was proposed to perform tests on lateritic soils blended with lithomargic fines in this study. The study focuses on correlating the effect of grain-size, maximum dry-density (MDD), and optimum moisture content (OMC) on the resilient modulus (Mr) measured using the cyclic tri-axial test for various blends of lateritic soils. Tests were performed on soil samples compacted to MDD for molding water contents set to the OMC, dry-side of OMC, and the wet-side of OMC. The results indicated that an increase in the fines-content resulted in an increase in the OMC, and a decrease in the MDD and Mr values. Regressions were developed correlating the fines content to the resilient modulus. This study is expected to provide the necessary basis for estimating the strength of a wide variety of lateritic sub-grades based on the fines content. © 2018, Springer International Publishing AG, part of Springer Nature.