Faculty Publications
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Item Comparative study on bearing capacity of bottom ash-stabilized soil mixed with natural and synthetic fibers(ASTM International service@astm.org, 2020) Prasannan, S.; Kolathayar, S.; Sharma, A.K.This article assesses the strength behavior of bottom ash (BA)-stabilized soil mixed with different fibers through a series of laboratory tests. Optimum BA and fiber percentage were obtained by small scale lab tests like compaction tests and unconfined compressive strength (UCS) tests. From compaction tests with varying proportions of BA (10, 20, 30, and 40 %), the optimum BA content was found to be 30 %. With this optimum BA content, UCS tests were conducted on soil-BA mix with different fibers (coir, areca, sisal, and polyvinyl alcohol) at various percentages (0.5, 1, 1.5, and 2 %) to find the optimum fiber content. A set of model footing tests were done to check the credibility of using fibers as a strengthening material beneath footing to upgrade the engineering properties of soil to make a reasonable subsoil for the foundation. A total of six model footing tests were performed on raw soil, on soil with optimum BA content, and on BA-stabilized soil mixed with different fibers in their optimum percentage (1.5 %). The bearing capacity of unstabilized unreinforced soil was found to increase significantly with the inclusion of fibers. © © 2020 by ASTM InternationalItem Performance of Footing on Clay Bed Reinforced with Coir Cell Networks(American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2020) Kolathayar, S.; Narasimhan, S.; Kamaludeen, R.; Sitharam, T.G.Geocells are three-dimensional polymeric hexagonal pockets that provide lateral confinement to the soil, thereby increasing the bearing capacity of the soil bed. This paper briefly reviews past studies on geocell reinforcement of soil and presents a new product, cells made out of natural coir fiber, as an alternative to commercially available high-density polyethylene (HDPE) geocells. A series of model plate load tests were conducted on unreinforced soil and on soil reinforced with coir geocells to understand the soil reinforcement mechanism. It was observed that with the introduction of coir geocells, the load-bearing capacity of the soil bed increased up to three times and a significant reduction in the settlement was observed in the underlying weak soil bed. The study also presents a comparative performance evaluation of the natural coir cell-reinforced soil with conventional HDPE geocell-reinforced soil. Further, this paper analytically demonstrates the influence of the lateral resistance effect and vertical load dispersion effect incorporated by coir cells in strengthening the soil bed. © 2020 American Society of Civil Engineers.Item Comparative Study for Performance of Soil Bed Reinforced with Jute and Sisal Geocells as Alternatives to HDPE Geocells(Springer Science and Business Media Deutschland GmbH, 2020) Kolathayar, S.; Sowmya, S.; Priyanka, E.This paper presents the performance of soil bed reinforced with jute and sisal geocells compared to HDPE geocells. The bearing pressure–settlement behaviour of the soil bed reinforced with natural geocells, soil bed reinforced with HDPE geocells and of unreinforced soil bed are discussed. The soil bed reinforced with jute cell and sisal cell showed a uniform increase in the settlement with increase in the applied pressure. The soil reinforced with HDPE geocell, however, showed a sudden rise in the settlement at higher pressure. Sisal mat used for developing the geocell was found to have greater tensile strength, followed by jute mat over HDPE material. Soil reinforced with sisal cells could bear larger stresses at lower strain compared to HDPE geocell. Analytical studies on jute and sisal geocells also were carried out considering the load transfer mechanism of geocell-reinforced soil. © 2020, Springer Nature Switzerland AG.Item Near-surface seismic refraction tomography and MASW for site characterization in Phuentsholing, Bhutan Himalaya(Springer Nature, 2021) Sarkar, R.; Kolathayar, S.; Drukpa, D.; Choki, K.; Rai, S.; Tshering, S.T.; Yuden, K.It is essential to understand the soil characteristics of the subsurface layers for any engineering construction. In difficult terrains like hilly areas, conventional methods of investigation are expensive and difficult to conduct. It calls for nondestructive testing methods to get reliable estimates of subsurface properties. In the present study, seismic refraction tomography (SRT) technique and multichannel analysis of surface waves (MASW) methods were carried out along five selected profiles in Phuentsholing region of Bhutan Himalaya. The profile length ranges from 37 to 81.5 m, and depth of imaging down to 10 m. While the SRT data imaged the P-wave velocity (Vp) structures, the MASW imaged the shear wave velocity (Vs) structures. The P-wave images provide a fair knowledge of geological layers, while the MASW images provide S-wave velocity structures (Vs). These results are useful to estimate soil parameters, like the density, Poisson’s ratio, Young’s modulus, shear modulus, N-value and the ultimate bearing capacity. The seismic images reveal the presence of sand, sandy clay, gravels and shale layers below the selected sites. Bhutan Himalayas being seismically vulnerable, the obtained results in terms of shear wave velocity were accustomed to categorize the sites as per NEHRP site classes, and a ground response analysis was performed to determine the reliable amplification factors. From the study, it is suggested that the engineering construction is feasible at all the sites except in one site, where an indication of saturated soil is observed which is vulnerable for liquefaction, and ground needs to be improved before construction at that site. © 2021, The Author(s).Item Model Footing Tests and Analytical Studies on Clayey Soil Bed Reinforced with Coconut Shell Mat(Springer Science and Business Media Deutschland GmbH, 2022) Kolathayar, S.; Gadekari, R.S.The cellular confinement systems are becoming popular in ground improvement because of their efficiency in improving the bearing capacity of soil due to the lateral confinement effect. The commercially available geocells are made from polymer materials and they are costly. This study presents the performance evaluation of coconut shell mat as a cellular confinement system in clayey soil. It is the first of its kind application of coconut shells for soil reinforcement through a lateral confinement mechanism. This soil reinforcement system using coconut shells is termed “Geococoshell” by the authors. A series of model plate load tests were conducted on unreinforced soil, soil reinforced with High-Density Polyethylene (HDPE) geocells, and soil reinforced with coconut shell mats to evaluate the performance of coconut shell mat reinforced soil bed. The results of the experiments showed that coconut shells reinforced clayey soil improved bearing capacity up to 1.5 times compared to HDPE geocell reinforced clayey bed. The effect of different patterns of placing coconut shell mat was also studied and discussed in the paper. The analytical studies have been conducted considering the reinforcement mechanisms of coconut shell mat embedded in the soil bed. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Lateral Resistance of Finned-Piles in c– ϕ Soils: Experimental Investigations and Numerical Studies(Springer, 2023) Bariker, P.; Kolathayar, S.; Chandrasekaran, S.S.Finned pile foundation systems are advantageous at resisting lateral loads, particularly for offshore foundations. They can replace large-dimension monopiles. This paper evaluates the lateral load resistance of finned piles for onshore foundation applications. The dimensionless factor fin-efficiency is used to quantify the improvements in the resistance caused by the fins. This study performed a series of small-scale model experiments for long piles embedded in c– ϕ soil. The numerical studies were performed with finite element approach. The paper presents the influence of fin-factors such as fin-position, width, length, orientation, embedment in pile cap, and eccentric loading on lateral resistance of finned pile. This study also suggests the optimum fin parameters that help increase the lateral resistance to the maximum possible. The study on effect of fin-embedment in pile cap shows that finned piles with fin embedded in pile cap (FP-FEPC) perform better than those without fin embedment (FP-WFE). The material cost-benefit study supported the economy of the construction with the finned pile, utilizing only 55% of the material used by the regular pile. © 2023, The Author(s), under exclusive licence to Indian Geotechnical Society.Item An Appraisal of the Mechanism and Research Development Status of Anti-slide Piles as Effective Technique for Landslide Risk Reduction(Springer, 2024) Jose, D.; Kolathayar, S.; Nayak, S.The increased frequency of landslides and associated devastations necessitates developing sustainable mitigation measures. The present paper aims to appraise the research developments in enhancing slope stability using anti-slide piles for landslide mitigation. The previous researchers made an immense effort to identify the soil–structure interaction of the anti-slide pile. The soil arching between the piles was identified as the soil–pile interaction mechanism. A detailed review of the soil arching between the piles is performed, and the observations are presented in detail. Recently, different sustainable methods for the analysis and design of anti-slide piles have been developed. An attempt was made to carry out a comprehensive review of the analysis methods and their critical features, and the observations are provided. The parameters affecting the performance of the anti-slide piles were identified, and the influence of those parameters on the behavior of piles is also discussed. Finally, the novel designs developed by researchers to overcome the limitations of conventional anti-slide piles and the utilization of sustainable materials as anti-slide piles were appreciated. The authors like to highlight that anti-slide piles are an effective solution for landslide risk reduction, and there is further scope for research in this field. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.Item Optimizing nailing parameters for hybrid retaining systems using supervised learning regression models(Springer Science and Business Media B.V., 2024) Menon, V.; Kolathayar, S.The work focuses on creating a hybrid retaining wall using geocell, geogrid, and soil-nailing techniques for a road embankment in Mangalore, India. Soil nailing reinforces the soil, geogrids give extra support, and geocell serves as a protective facia against external weathering impacts, decreasing the requirement for conventional shotcreting and lowering the carbon footprint of concrete. This promotes the United Nations’ Sustainable Development Goals (SDGs). The usage of concrete and steel in soil nailing can be minimized using supervised learning regression models (SLRMs), a branch of machine learning (ML). The soil properties in the site were collected by standard penetration tests (SPT). From the limit equilibrium method (LEM) study, 600 iterations are carried out to estimate the factor of safety (FoS), which serves as input training and testing data for the ML model. The surrogate model produces findings for the entire site to identify ideal nail parameters. The random forest (RF) model was found to be useful with a mean square error (MSE) value of 0.009. The finite element method analysis (FEM) yields a modest overestimation of roughly 4.5% while validating the results of the RF model in a typical slope. This study demonstrates the practical application of sustainable methodologies and machine learning to meet crucial development goals, explicitly improving slope stability and road development in the study area through environmentally conscious engineering practices. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Debris flow in c-? soil: experimental analyses of pore pressure variations, crack percentage, digital image correlation (DIC) and particle image velocimetry (PIV)(Springer, 2025) Menon, V.; Kolathayar, S.Debris flow is the aftermath of soil losing its strength due to an increase in moisture content, which is initiated by Rainfall. This study investigates rainfall-induced debris flow in c-? soil predominantly found in the Western Ghats, India. The experimental setup utilised the tilting flume technique to simulate a 45-degree slope, replicating field conditions in terms of field density and natural moisture content. Excess pore water pressure (EPWP) variations were monitored during simulated rainfall events with an intensity of 30 mm/h. The findings indicate that the decrease in EPWP observed during the experiments Following a peak value and coincides with the initiation of soil movement, which occurs after the formation of shear cracks on the soil surface. To substantiate these observations, a masking algorithm based on OpenCV was employed to analyse fluctuations in crack percentage. Particle image velocimetry (PIV) and Digital Image Correlation (DIC) quantified particle velocity-displacement dynamics using high-definition camera imagery over time, which validated the initiation of landslides. It was observed that the rapid decline in EPWP serves as a critical precursor to potential landslide occurrences, underscoring the pivotal role of these metrics in early landslide prediction and risk assessment. This research contributes valuable insights into understanding landslide mechanics under controlled laboratory conditions, with implications for early landslide detection and hazard mitigation strategies in landslide-prone regions. © Indian Academy of Sciences 2025.