Faculty Publications

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Author: search.filters.author.Kumar, A.Subject: search.filters.subject.correlation

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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.
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    Effect of soil parameters on modulus of resilience based on portable falling weight deflectometer tests on lateritic sub-grade soils
    (Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) George, V.; Kumar, A.
    The use of portable falling weight deflectometers (PFWDs) has gained prominence among pavement engineers in the characterisation of soil sub-grade based on modulus of stiffness. The values of modulus of resilience and the corresponding values of the rebound deflection measured using the PFWD are largely influenced by the soil stiffness. The focus of the present investigation is on the study of the effect of soil parameters such as grain size distribution, maximum dry density (MDD) and optimum moisture content (OMC) on the values of modulus of stiffness (E PFWD) obtained using the PFWD for tests performed on lateritic soil blends. Tests were conducted on various blends of lateritic soil samples compacted to MDD at moulding water contents set to the optimum moisture content (OMC), dry-side of optimum at OMC?3% and wet-side of optimum at OMC+3%. The regressions developed between the values of E PFWD and the percentage of fines and the percentage of sand for lateritic and lithomargic soils indicate a strong linear relationship between these variables for tests on un-soaked and soaked soils. The regressions developed will be of immense benefit to pavement engineers in estimating the values of the modulus of resilience for lateritic soils for the design of pavement sub-grades and embankments. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.