Faculty Publications

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    Geohazard Investigation and Management: An Introduction
    (Springer Science and Business Media Deutschland GmbH, 2022) Adhikari, B.R.; Menon, V.; Kolathayar, S.
    The understanding of the systemic risk posed by multi-hazard is becoming a new area of research and adopted by the different global and national frameworks. This chapter summarizes the contents of the book titled geohazard mitigations, which contains thirty-eight chapters. These chapters are divided into three sections namely: multi-hazard assessment, landslide hazard assessment and mitigation, and geotechnical engineering. This chapter also includes basic definitions and introduction to geohazard investigation and management. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    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.
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    Computer aided slope stability analysis
    (2006) Sastry, V.R.; Ram Chandar, K.; Santosh, M.
    Primary purpose of slope stability analysis in most of the engineering applications is to provide safe and economic design of slopes that prevent failure. The analysis technique chosen depends on both site conditions and potential mode of failure which depends upon the rock mass characteristics. Various slope stability analysis techniques include physical, numerical and analytical methods. Physical modeling is a time consuming process and a costly affair, while analytical method involves past experiences, it is site specific and depends upon various parameters which are difficult to quantify. Numerical analysis with sophisticated softwares provides an accurate solution within short duration. This paper presents an in-house developed software package called "V-slope" to analyze and interpret the slope with options for suggesting suitable safety measures based on the nature of slope. Slip circle and tension crack techniques were considered for analysis. The slope profile for different factor of safety (FOS) values will be displayed on the screen for easy understanding. In case the FOS is lower than the required, the V-slope gives suggestive measures. In case of temporary slopes the only way by which slope failure can be prevented is by decreasing the slope angle and in such cases the program gives additional volume of material to be excavated and the likely additional cost incurred for various slope angle options. For permanent slopes, option is provided for designing the soil nails, i.e. number of bolts required, length, diameter and spacing of the bolts etc. Finally the V-slope is compared with a comprehensive commercial software package Slide and the results were found very much satisfactory.
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    Performance of stone columns with circumferential nails
    (2011) Nayak, S.; Shivashankar, R.; Dheerendra Babu, M.R.D.
    Stone columns are often used as an effective technique for improving the performance of soft ground. Stone columns derive their load-carrying capacity due to lateral confinement from the surrounding soil. Very soft soils offer very low lateral confinement, leading to large settlements and low load-carrying capacities. In this paper, an alternative method of enhancing the performance of stone columns in soft soils by reinforcing the stone columns with circumferential nails driven vertically is suggested. The method was developed in laboratory-scale model tests and a series of plate load tests were performed in unit cell tanks to investigate the performance of stone columns reinforced with circumferential nails. The investigation was carried out by varying the depth of nails below ground level, the number of nails and the diameter of nails with different diameter stone columns and area ratios (orspacing). It was found that the circumferentially reinforced stone columns have much higher load-carrying capacity with a significant reduction in settlement and less lateral bulging in comparison with plain stone columns.
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    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.
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    A Numerical Study on the Shear Strength of Pervious Concrete Column in Weak Ground
    (Southeast Asian Geotechnical Society, 2022) Rashma, R.S.V.; Jayalekshmi, B.R.; Shivashankar, R.
    In this study, the response of pervious concrete column-treated ground under shear loading is examined by employing a series of numerical analyses. The shear behaviour of pervious concrete column-treated ground is compared with stone column-treated ground and weak ground. Two types of analyses were carried out to assess shear strength of the composite ground. Conventional direct shear test model and large shear test models were evaluated using ABAQUS software. The pervious concrete column-treated ground is observed to have greater shear strength than the mere stone column-treated ground. The lateral deflection pattern of the pervious concrete column is also noticed to be very much lesser than conventional stone columns under static shear loading. The overall shear performance of the pervious concrete column-treated ground is found to be improved than the typical stone column-treated ground. © 2022, Southeast Asian Geotechnical Society. All rights reserved.
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    Influence of Separation Layer Properties on Seismic Response of Modified Piled Raft Foundations
    (Springer, 2025) Amalu, P.A.; Jayalekshmi, B.R.
    Conventional piled raft foundations, with the raft and piles interconnected, severely restrict lateral movement, especially during seismic events. These constraints result in substantial stresses at the connection, posing a risk of potential breakage. Therefore, in seismic-prone areas, where transient lateral loadings of larger magnitudes are expected, conventional piled raft foundations are not feasible. Providing a separation layer between the raft and pile foundations is a viable solution to improve the performance of conventional piled raft foundations. The performance of such a modified piled raft system depends largely on the properties of the separation layer introduced. However, limited studies have been conducted to evaluate the seismic performance of these separation layers by considering the effect of soil–structure interactions. The present study thus aims to investigate the performance of modified piled raft systems by comparing them with their conventional counterpart. The existing conventional piled raft foundation of the Treptower building has been chosen as the prototype and is numerically analysed for static and dynamic loading conditions. Further, a separation layer has been introduced between the pile and raft, and the performance of the modified piled raft foundation is analysed under similar loadings. The results of these analyses are comprehensively compared to ascertain the performance of modified piled rafts under seismic excitation. It is found that the modified piled raft foundation with PE foam in the separation layer is advantageous in damping the propagation of seismic waves to the superstructure, reducing settlement and lateral displacements, and thereby decreasing the potential risk of failure of superstructures in seismic-prone areas. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.