Faculty Publications
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Item Effect of pH on the geotechnical properties of laterite(2006) Sunil, B.M.; Nayak, S.; Shrihari, S.Environmental Geotechnology has emerged as an interdisciplinary science, aiming and forecasting, analyzing and solving the geotechnical problems involving the influence of environmental factors. Lateritic soil of west coast region of India was studied to investigate the effect of soaking on the engineering properties and chemical characteristics of soil, soaked in different pH solutions (pH = 5.0, pH = 7.0, pH = 8.0). 12 N hydrochloric acid and 15 M ammonia solution were used to monitor the pH of the solution for about ninety days. Results showed that the pH of the solution has strong influence on the chemical characteristics of lateritic soil. The engineering properties of soil are altered when compared with the initial characteristics of the soil. The reason for this observed behavior of the soil is addressed in this paper. © 2006 Elsevier B.V. All rights reserved.Item Interactions Between Soils and Laboratory Simulated Electrolyte Solution(2010) Nayak, S.; Sunil, B.M.; Shrihari, S.; Sivapullaiah, P.V.To study the impact of salt water intrusion on two types of soils from west coast region of India were investigated in the laboratory. The key characteristics evaluated included Atterberg limits, compaction characteristics, hydraulic conductivity and chemical characteristics of selected soils. The sea at this coast receives effluent from different points and hence the characteristics change with time and locality. Therefore, to maintain uniform composition, 0.5 N sodium chloride solution (NaCl) was prepared in the laboratory and batch tests were used to determine the immediate effect on soils. Soil specimens were prepared by mixing the soils with 0.5 N NaCl in the increments of 0, 5, 10 and 20% by weight to vary the degree of contamination. Experimental results of soils mixed with 0.5 N NaCl showed that the maximum dry density increases and the optimum moisture content (OMC) decreases with increasing sodium chloride concentration. The study also revealed that the hydraulic conductivity of the soils tested increases with increase in sodium chloride concentration. The Atterberg limits of contaminated specimens show a remarkable change when compared with uncontaminated specimens. © 2010 Springer Science+Business Media B.V.Item Geotechnical characteristics of lithomargic clay blended with marine clay as landfill liner material(CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2012) Allamaprabhu, K.; Sunil, B.M.; Nayak, S.; Fernandes, S.; Zafar, M.This paper reports a series of laboratory tests conducted on lithomargic clay (shedi soil), which is widespread over part of southwest coast of India, to assess whether it could be used as compacted clay liner for hydraulic barriers in engineered landfill. In order to assess the suitability of lithomarge as a barrier material, following tests such as index properties, compaction characteristics, hydraulic conductivity and unconfined compressive strength of the soil were conducted in the laboratory. From the studies, it is found that lithomargic soil is near to the recommended specifications for soils to be used as liner material. Suitable materials for soil liners are then obtained by blending different types of locally available soils to achieve the required low hydraulic conductivity and good strength. To achieve specifications for the liner material lithomargic clay is blended with 15% and 20% marine clay by weight of lithomargic clay. From standard compaction control, the blended soil shows hydraulic conductivity lower than the 1x10-7 cm/s. Acceptable zones (AZ) are constructed on the compaction plane to meet design objectives for hydraulic conductivity. It's strength properties show that the soil possesses higher strength than the recommended minimum strength of 200kPa, to support the overburden pressure imposed by the waste body. From the laboratory test results, it can be concluded that lithomargic clay blended with marine clay satisfies the requirements for a good soil liner material. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Performance of granular columns in dispersive soils(Thomas Telford Services Ltd ttjournals@ice.org.uk, 2014) Nayak, S.; Dheerendra Babu, M.R.; Shivashankar, R.; James, N.The soils found abundantly along the Konkan belt in peninsular India are lateritic soils and lithomargic clays. The locally available lithomargic clayey soils are problematic in the sense that their strength reduces drastically under saturation conditions, which is typical behaviour of the dispersive type of soil. Most foundations are placed on this soil layer. This paper presents results from a series of laboratory plate load tests carried out in unit cell tanks to investigate the behavior of granular columns in these weak (lithomargic clay) grounds. Tests are carried out with two types of loading: with the entire area in the unit cell tank loaded, to estimate the stiffness of the improved ground; and with only the granular column area loaded, to estimate its limiting axial capacity. Investigations were carried out by varying the area ratio (or spacing), diameter of granular columns, end condition and column configuration. The load-settlement behaviour, stiffness and bulging behaviour of granular columns are analyzed. It is found that the ground treated with granular columns exhibits a high load-carrying capacity and stiffness, and a significant reduction in settlement, compared with the untreated ground. © Ice publishing: All rights reserved.Item SEM and XRD investigations on lithomargic clay stabilized using granulated blast furnace slag and cement(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) C. Sekhar, D.; Nayak, S.Lithomargic clay soil is found along the western coast of southern India extending from Cochin to Goa below hard lateritic soil varying in large depths. This soil is problematic as it loses its strength upon saturation and is mainly consisting of silt size particles. Granulated blast furnace slag is a by-product from the iron industry available in large quantities. Since it has high percentage of CaO (i.e. 30–45%), it has latent hydraulic properties. Laboratory experiments were conducted to improve the strength properties of lithomargic clay by replacing soil with varying percentages of GBFS. Lithomargic clay stabilised with 25% GBFS was found to be the optimum. Further addition of 2 and 4% cement to the optimised slag–soil mix improves the strength properties significantly. SEM and XRD analyses were carried out to observe the microstructural changes in the stabilised soil. The reason for the improvement in strength was established through SEM and XRD. C-S-H, C-A-S-H and few other similar compounds were responsible in improving the strength properties by filling the voids between the soil particles. From the quantitative EDS analysis, it was concluded that the strength improvement was due to the increase in Ca:Si ratio and decrease in Al:Ca ratio. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.Item Experimental Studies and its Application using PLAXIS-2D for Lithomargic Clay Stabilized by GBFS and Lime(Springer Science and Business Media Deutschland GmbH, 2021) Mahesh Bhat, K.; Nayak, S.Lithomargic clay is found along the Eastern and Western coasts of Southern India. Presence of weak soils like lithomargic clay below the foundations, cause serious problems when they come in contact with water, and non-availability of stronger fill materials locally, to replace them is a challenge to foundation engineers. An attempt has been made in this paper to improve the strength of lithomargic clay by chemical stabilization using Lime and Granulated Blast Furnace Slag (GBFS). Disposal of massive amounts of industrial waste, GBFS, has become an environmental problem and utilization of the same for soil stabilization would be a sustainable solution for disposal. To optimize the use of lime and understand the mechanism behind the gain in strength, laboratory experiments were conducted on lithomargic clay, by replacing it with varying amounts of GBFS and addition of different percentages of lime. The optimum lime and GBFS content were found to be 4% and 20% respectively. Further optimization was done by mixing lithomargic clay with 4% lime and 20% GBFS and a significant strength improvement was observed. SEM and XRD analyses were conducted on the stabilized soil and the increase in strength was established from structural changes and formation of compounds like CSH and CASH. PLAXIS 2D was used to understand the settlement behavior of both the unstabilized and stabilized soils below strip foundations of varying widths. From load settlement analysis, it was observed that the net allowable pressure increases with increase in GBFS content and further increases with addition of lime to soil stabilised with optimum GBFS. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.