Browsing by Author "Nayak, S."

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3D Finite Element Analysis of Anti-slide Pile Performance for Slope Stabilization
(Springer Science and Business Media Deutschland GmbH, 2025) Jose, D.; Kolathayar, S.; Nayak, S.
The stability of the slope plays a significant role in the formation and development of landslides. Among numerous slope stabilizing techniques, the reinforcement using anti-slide piles is an efficacious method for mitigating slope failures. These piles are usually installed in a row with uniform spacing, which will anchor the unstable zone to the deeper stable strata, thus maintaining the stability of the slope. In this study numerical analysis of the pile reinforced was carried out using the finite element software PLAXIS 3D to appraise the performance of anti-slide piles for controlling landslides. The variation of the factor of safety with the pile position, pile spacing, pile length, and shape of the pile was identified based on the safety analysis using the strength reduction method. The anti-slide pile effectively stabilized the slope and enhanced the safety factor by 1.4 times. The fixity of the pile head influences the performance of anti-slide piles, and fixed-head piles excels than free-head piles. The optimum position for placing the pile was observed as the middle of the slope for fixed head piles and near the toe of the slope for free head piles. The optimum spacing between the piles is recommended to be five times the diameter of the pile. A critical pile length of 0.8 times the height of the slope is suggested for attaining the maximum factor of safety and effective anchoring, and square-shaped piles are recommended. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
A Critical Review of Construction, Analysis and Behaviour of Stone Columns
(Kluwer Academic Publishers, 2013) Dheerendra Babu, M.R.; Nayak, S.; Shivashankar, R.
Stone columns have been used as an effective technique for improving the engineering behaviour of soft clayey grounds and loose silt deposits. The soil improvement via stone columns are achieved from accelerating the consolidation of weak soil due to shortened drainage path, increasing the load carrying capacity and/or settlement reduction due to inclusion of stronger granular material. This paper discusses the techniques, methods of construction of stone columns, mechanisms of stone column behaviour under load and associated design philosophies along with some practical findings from recent research programs. © 2012 Springer Science+Business Media B.V.
A Review on Methods for Analysis of Laterally Loaded Piles
(Springer Science and Business Media Deutschland GmbH, 2022) Babu, A.; Nayak, S.
Pile foundations are often subjected to lateral loads and moments due to forces such as wind, waves and earthquake. The lateral response of a single pile is one among the main complex soil-structure interaction problems in foundation engineering. The behavior of the soil-pile system is mainly nonlinear, making the problem more complicated. The lateral load resistance of pile is influenced by the soil pile interaction, which in turn depends on soil properties, pile material, diameter of the pile, pile length, loading type etc. Several methods have been used for the analysis of vertical piles subjected to lateral loads, some of which have gained significant experience in applying the theory to practical situations. Realistic soil-pile interaction and pile behavior under lateral load can be simulated using software based on finite element analyses. A comprehensive literature review of different methods for the analysis of laterally loaded piles is discussed in this paper. The applicability, advantages, limitations and comparison of various methods are also included in the study. For the better understanding the entire review is segregated into different subsections on the basis of nature of analyses. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
A Review on the Design, Applications and Numerical Modeling of Geocell Reinforced Soil
(Springer Science and Business Media Deutschland GmbH, 2021) Vibhoosha, M.P.; Bhasi, A.; Nayak, S.
For improving the stability and load carrying capacity of weak subgrade, strengthening methods are to be followed in the field. Among the various approaches, geocells have been identified as an effective soil reinforcement technique for improving soft subgrade behaviour. The three-dimensional honeycomb structure of geocell offers more lateral confinement to the infill soil resulting in improved load carrying capacity. This led to the widespread use of geocells for different geotechnical applications like pavements, foundations, embankments, slope protection, erosion control etc. Many researchers in the past have confirmed the suitability of geocell reinforcement through their experimental, numerical and field studies. In this paper, a comprehensive review of the reinforcement mechanisms, design aspect and numerical modelling techniques of geocell reinforced soil is provided. In addition, this paper highlights the various field application scenarios where different types of geocells have been used and explores the research challenges and scope for further research in this field. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
A Study on the Behaviour of Stone Columns in a Layered Soil System
(Springer, 2020) Nayak, S.; Balaji, M.; Preetham, H.K.
Stone columns are one of the cost-effective and efficient methods for improving the ground which strengthen the soil and reduce the settlements. The study of the behaviour of stone columns in layered soils is of great importance. In this paper, results obtained from the experiments done on the stone columns with varying thickness of clayey silt soil (lithomargic clay) at bottom and the lateritic soil at the top are discussed. The lateritic layers are varied from top for a depth of 1D to 5D where D is the stone column diameter. Experiments were performed on untreated soils alone, soil with the ordinary stone column, geogrid encased stone column with and without additional horizontal reinforcement called basal layer to geogrid encased stone column in lithomargic clay. Similar experiments were conducted using lateritic soil. By considering layered combination of these two soils, experiments were also performed on ordinary stone column, geogrid encased stone column and geogrid encased stone column with basal layer. Laboratory tests were conducted in a unit cell on the floating stone column of diameter 60 mm. The load capacity of the stone column and bulging characteristics are significantly affected with the increase in the layers of lateritic soil. The encasement of stone column enhances the stone column’s capacity and reduces the bulging. The additional horizontal reinforcement layer also showed a significant impact on the load capacity of the stone column. Experiments conducted were modelled and analysed using PLAXIS 2D software package. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
An Alternative Method to Estimate Fundamental Period of Layered Soil Deposit
(2015) Vijayendra, K.V.; Nayak, S.; Prasad, S.K.
There are several approximate methods available for the estimation of fundamental period of layered soil deposits. Approximate methods based on weighted average of shear wave velocities of the layered soil profile are most widely employed in practice. On the other hand, methods which are more accurate are tedious and iterative in procedure; hence they are unpopular for quick estimation of fundamental period of soil deposits. A new method for computing the fundamental period of multilayered soil deposit is proposed in the present study. In this method, layered shear wave velocity profile is replaced with an equivalent linearly varying profile. Subsequently, based on analytical solution for fundamental period of the deposit with linearly varying shear wave velocity profile, an equation to estimate the fundamental period of the actual layered soil deposit is proposed. The efficiency of the proposed method and other available methods is relatively verified by comparing their results with values computed from recorded earthquake accelerograms of instrumented geotechnical downhole arrays. This comparative study, establishes accuracy and consistency of the proposed method vis- -vis exact methods. 2014, Indian Geotechnical Society.
An Alternative Method to Estimate Fundamental Period of Layered Soil Deposit
(Springer India sanjiv.goswami@springer.co.in, 2015) Vijayendra, K.V.; Nayak, S.; Prasad, S.K.
There are several approximate methods available for the estimation of fundamental period of layered soil deposits. Approximate methods based on weighted average of shear wave velocities of the layered soil profile are most widely employed in practice. On the other hand, methods which are more accurate are tedious and iterative in procedure; hence they are unpopular for quick estimation of fundamental period of soil deposits. A new method for computing the fundamental period of multilayered soil deposit is proposed in the present study. In this method, layered shear wave velocity profile is replaced with an equivalent linearly varying profile. Subsequently, based on analytical solution for fundamental period of the deposit with linearly varying shear wave velocity profile, an equation to estimate the fundamental period of the actual layered soil deposit is proposed. The efficiency of the proposed method and other available methods is relatively verified by comparing their results with values computed from recorded earthquake accelerograms of instrumented geotechnical downhole arrays. This comparative study, establishes accuracy and consistency of the proposed method vis-à-vis exact methods. © 2014, Indian Geotechnical Society.
An Analysis of Piled Slope with Single Row of Piles Using 2D Finite Element Analysis
(Springer Science and Business Media Deutschland GmbH, 2024) Jose, D.; Kolathayar, S.; Nayak, S.
The increased frequency of landslides and the associated damages emphasize the need to develop novel techniques for landslide mitigation. Among numerous methods developed till today, an anti-slide pile is an effective tool for controlling slides in landslide-prone areas. The present study assesses the suitability of 2-D FE analysis using the strength reduction method for analyzing a slope stabilized with anti-slide piles. A detailed parametric study was carried out to explore the influence of the position and length of the pile on the factor of safety of pile-reinforced slopes, and the failure mechanism was studied in detail. Fixed head piles improved the safety factor compared to free head piles, and an improvement of 1.5 times was obtained compared with unreinforced slope. Piles located at the crest and toe of the slope were not significantly improving compared to other locations. For fixed head piles, the length of the pile does not affect the factor of safety, and for free head piles, the factor of safety improves with an increase in the length of the pile. For the slope considered in the study, the optimum position of the pile is between the crest and middle portion of the slope, and the optimum length is found to be 20Â m for free head piles and 10Â m for fixed head piles. The failure mechanism of the piled slope is also explained in detail for each case. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
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.
Analysis of Geocell-Reinforced Stone Column-Supported Embankment Considering Soil-Structure Interaction
(Springer, 2022) Vibhoosha, M.P.; Bhasi, A.; Nayak, S.
Geocells are a superior form of reinforcement due to their cost-effectiveness and three-dimensional confining properties. The effect of the basal geocell layer on the performance of the stone column-supported embankment was evaluated in this paper by carrying out time-dependent coupled analyses considering the geocell-infill soil interactions. The various parameters, such as arching, stress concentration ratio, surface settlement, column bulging characteristics, and the influence of various types of infill materials and drainage blanket thickness on column-supported embankment behavior, were analyzed. The load transfer mechanism was quantified using the term stress concentration ratio, and with the use of geocell mattress above stone columns, the stress concentration ratio increased by 1.5 times that of ordinary stone columns. Also, it was observed that compared to ordinary stone column-supported embankment, the combination of stone columns with geocell-sand mattress resulted in a further reduction of the foundation settlement by 15%. Analysis results showed that the arching behavior is not predominant in geocell-reinforced columnar structures. The various analytical methods like Guido et al. (1987), Low et al. (1994), and Abusharar et al. (2009), which were developed for geosynthetic reinforced columnar embankments, were found to significantly under-predict the stress reduction ratio values with geocells. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Anti-diarrheal potential of Aegle Marmelos Corr. root bark extract in rats
(2007) Vrushabendra, S.B.M.; Nataraj, K.S.; Jayaveera, K.N.; Gopkumar, P.; Nayak, S.; Kumar, G.S.; Umachigi, S.P.
A study was undertaken to evaluate the effect of methanolic extract of the rootbark of Aegle marmelos Corr. (MAMC) against several experimental models of diarrhoea in rats. MAMC treated animal's showed significant inhibitory effect against castor-oil induced diarrhea and PGE2 induced enteropooling in rats. The extract also showed a significant reduction in gastrointestinal motility in the charcoal meal test in rats. The results obtained to establish the efficacy and substantiate the folkare claim as an anti-diarrhoeal agent.
Anti-diarrheal potential of Aegle Marmelos Corr. root bark extract in rats
(2007) Vrushabendra Swamy, S.B.M.; Nataraj, K.S.; Jayaveera, K.N.; Gopkumar, P.; Nayak, S.; Kumar, G.S.; Umachigi, S.P.
A study was undertaken to evaluate the effect of methanolic extract of the rootbark of Aegle marmelos Corr. (MAMC) against several experimental models of diarrhoea in rats. MAMC treated animal's showed significant inhibitory effect against castor-oil induced diarrhea and PGE2 induced enteropooling in rats. The extract also showed a significant reduction in gastrointestinal motility in the charcoal meal test in rats. The results obtained to establish the efficacy and substantiate the folkare claim as an anti-diarrhoeal agent.
Assessment of the Geotechnical Properties of Red Earth Stabilized Using Quarry Dust and Cement
(Springer Science and Business Media Deutschland GmbH, 2022) Nayak, S.; Preetham, H.K.; Prakash, S.D.
The present investigation aims at improving the engineering properties of red earth by incorporating quarry dust (QD) and analyze the results thus obtained by conducting a comparative study with the basic soil. Red earth is widely spread over a large part of peninsular India. Red earth/red soil could yield better results by the addition of rough-textured granular quarry dust and a hydraulic binder like cement. QD is the output from the rubble crushing units. Red earth was replaced with different proportions of quarry dust by dry mass of the soil: QD (5â€“30%, with an increment of 5%) with cement (2â€“6%) for the optimum QD-soil mix. The geotechnical properties like specific gravity, consistency limits, compaction, unconfined compressive strength (UCS), and triaxial compression test were performed on the red earth as well as on the mixes as per Indian Standard Codal provisions. UCS test results conclude that an optimum percentage of replacement of red earth by QD is 10% which yielded maximum strength than other mixes. It was observed that on replacement of red earth by granular quarry dust and cement, the shear strength properties and other geotechnical properties were improved. Thus, the utilization of granular industrial by-products has proven to be socially and economically beneficial. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Characterization of climatic parameters in the perspective of irrigated agriculture in Uttar Kannada district of Karnataka, India
(India Meteorological Department mausamps@gmail.com, 2020) Yallurkar, S.; Nayak, S.; Nandagiri, L.
A rainfall and potential evapotranspiration characteristics together determine the agro-meteorological regime of a region and influences decision concerning the magnitudes and timing of irrigation application. In the present study, historical rainfall and climate data pertaining to the study area, Uttar Kannada district, Karnataka, was analyzed with a view to characterizing irrigation water requirements. In addition to rainfall input, an important aspect of the water balance model is the crop evapotranspiration (ETcrop), which is the main factor in determining the irrigation schedule. ETcrop could be estimated by reference evapotranspiration (ET0) and crop coefficient. Atmospheric demand for water is represented by ‘potential evapotranspiration’ (PET) and calculated from climatic variables which is crucial for irrigation planning. It has been reported that the Penman-Monteith method gives more consistently correct ET0 estimates to other ET0 methods. While recognizing the importance of both rainfall and PET, an effective measure is known as the ‘Moisture Availability Index’ (MAI), which is computed as the ratio of 75% dependable rainfall and potential evapotranspiration. An MAI value of 1.00 indicates that dependable precipitation is equal to potential evapotranspiration. An MAI value of 0.33 or less for one month during the crop growing season is considered to be a signal of water deficit resulting reduction in crop yield. The findings of this study on MAI are used to decide the selection of the sowing period of crops so as to avoid water stress during the critical harvesting period. © 2020, India Meteorological Department. All rights reserved.
Characterization of small-scale groundwater irrigation schemes in a humid coastal region of southern India
(2009) Nayak, S.; Nandagiri, Lakshman
Small-scale groundwater irrigation schemes involving large diameter wells are prevalent in the coastal district of Uttara Kannada, Karnataka State, India. A study was conducted to assess the characteristics of these large diameter open wells and the hydraulic properties of shallow aquifers. Field tests were conducted in 19 wells to assess their potential to supply irrigation water requirements of the region. Constant discharge pump tests indicated significant spatial variations in aquifer transmissivity (5.60 to 64.55 m2 day-1) and specific yield (0.063 to 0.95). Low transmissivity values signify poor potential of the aquifer to supply irrigation water needs. Exponential prediction models linking transmissivity and well specific capacity gave a good fit. Implications of spatial variability in aquifer parameters on irrigation development in the region are highlighted.
Characterization of small-scale groundwater irrigation schemes in a humid coastal region of southern India
(2009) Nayak, S.; Nandagiri, L.
Small-scale groundwater irrigation schemes involving large diameter wells are prevalent in the coastal district of Uttara Kannada, Karnataka State, India. A study was conducted to assess the characteristics of these large diameter open wells and the hydraulic properties of shallow aquifers. Field tests were conducted in 19 wells to assess their potential to supply irrigation water requirements of the region. Constant discharge pump tests indicated significant spatial variations in aquifer transmissivity (5.60 to 64.55 m2·day-1) and specific yield (0.063 to 0.95). Low transmissivity values signify poor potential of the aquifer to supply irrigation water needs. Exponential prediction models linking transmissivity and well specific capacity gave a good fit. Implications of spatial variability in aquifer parameters on irrigation development in the region are highlighted.
Determination of displacement-related passive earth pressure
(2004) Rao, K.S.S.; Nayak, S.; Choudhury, D.
The mobilisation of earth pressure depends on the magnitude of displacement. Large displacements are required for the full mobilisation of the passive earth pressure compared to that required for full mobilisation of the active earth pressure. In this paper, a semi-empirical approach for the determination of displacement-related passive earth pressure is presented. The approach is based on the establishment of mobilised friction angle for any wall movement. The experimental observations made by earlier researchers are analysed for three modes of rigid body movements, namely, translation, rotation about the top (RT) and rotation about the bottom (RB). Using tables from Kerisel and Absi to estimate the mobilized friction angles, equations are developed for the conservative estimate of passive earth pressure for all modes of wall movements, which can be used to get displacement related passive earth pressure. An illustrate example shows the use of the proposed equations for obtaining the displacement-related passive earth pressure distribution for all the three kinds of rigid wall movements. The suggested semi-empirical approach is applied to a retaining wall problem demonstrating its rationality and cost effectiveness.
Effect of Cement and Quarry Dust on Shear Strength and Hydraulic Characteristics of Lithomargic Clay
(2012) Nayak, S.; Sarvade, P.G.
The lithomargic clay constitutes an important group of residual soils existing under lateritic soils. This soil is found on the western and eastern coasts of India over large areas. This soil is a problematic one and is very sensitive to water and loses a greater part of its strength when becomes saturated. These high silt deposits have invited many problems such as slope failures, foundation failures, embankment failures, uneven settlements etc. In this investigation an attempt is made to study the effect of cement and quarry dust on shear strength and hydraulic characteristics of the lithomargic clay after the stabilization. Microfabric and mineralogical studies were carried out to find out the reason for the strength development of the stabilized soil using SEM and XRD analysis. The results indicated that there is an improvement in the properties of the lithomargic clay with the addition of cement and quarry dust. The XRD results indicated the formation of CSH and CAH, which are responsible for strength development in the stabilized soil. 2011 Springer Science+Business Media B.V.
Effect of Cement and Quarry Dust on Shear Strength and Hydraulic Characteristics of Lithomargic Clay
(2012) Nayak, S.; Sarvade, P.G.
The lithomargic clay constitutes an important group of residual soils existing under lateritic soils. This soil is found on the western and eastern coasts of India over large areas. This soil is a problematic one and is very sensitive to water and loses a greater part of its strength when becomes saturated. These high silt deposits have invited many problems such as slope failures, foundation failures, embankment failures, uneven settlements etc. In this investigation an attempt is made to study the effect of cement and quarry dust on shear strength and hydraulic characteristics of the lithomargic clay after the stabilization. Microfabric and mineralogical studies were carried out to find out the reason for the strength development of the stabilized soil using SEM and XRD analysis. The results indicated that there is an improvement in the properties of the lithomargic clay with the addition of cement and quarry dust. The XRD results indicated the formation of CSH and CAH, which are responsible for strength development in the stabilized soil. © 2011 Springer Science+Business Media B.V.
Effect of Column Configuration on the Performance of Encased Stone Columns with Basal Geogrid Installed in Lithomargic Clay
(2019) Nayak, S.; Vibhoosha, M.P.; Bhasi, A.
Lithomargic clay is extensively found along the Konkan belt in peninsular India and serves as a foundation for most of the structures. The reduction in strength under saturated conditions makes this soil problematic causing a lot of engineering problems such as uneven settlements, erosion, slope failures, and foundation problems. This paper presents the effect of column configuration (i.e. equivalent number of columns with reduced diameter for the same surface area) on the performance of lithomargic clay reinforced with geogrid encased stone columns and basal geogrid layer. The investigations were performed both experimentally through small-scale models and through finite element analyses. The results were compared with the performance of lithomargic clay reinforced with ordinary and encased stone columns. A single geogrid encased stone column with a basal geogrid layer improved the load-carrying capacity of lithomargic clay by 180% while the percentage of increment in the case of a group of three geogrid encased stone column with basal geogrid layer having the same surface area was 210%. It was also observed that the geogrid encasement of stone columns reduced the maximum column bulging by 38%, whereas geogrid encased stone columns along with basal geogrid layer reduced the bulging by 82% compared to ordinary stone columns. 2019, Springer Nature Switzerland AG.