Browsing by Author "Sridhar, G."

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A Critical Analysis of Curve Fitting Procedures Used in Evaluating Co-Efficient of Consolidation of Soils
(Springer Science and Business Media Deutschland GmbH, 2025) Athira, S.; Sridhar, G.
Consolidation settlement is the time-dependent phenomenon. Coefficient of consolidation is essential to estimate the rate of settlement of structures founded on saturated fine-grained soil. One of the common methods used to determine the coefficient of consolidation is through curve-fitting procedure. These procedures involve fitting a theoretical model to experimental data obtained from laboratory tests, such as the oedometer test. The Casagrande log t method and Taylorâ€™s root t method are the standard methods to find the vertical coefficient of consolidation (cv). To design vertical drains, Barronâ€™s theory is commonly used which requires coefficient of radial consolidation (cr). Over the past decade, several curve-fitting procedures namely the inflection method, rectangular hyperbola method, one-point method, early-stage log t method and many more, have been developed to determine either vertical or radial coefficients of consolidation. This paper provides a comprehensive review of procedures used for computing the vertical and radial coefficient of consolidation, offering a comparative analysis with advantages, limitations, and practical use of each method. Also, cv and cr of kaolin clay are determined through various methods. This assessment will be helpful to both academics and working engineers in accurately choosing the appropriate method for estimating the rate of settlement in saturated fine-grained soils. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
A Critical Review on Potential Use of Waste Foundry Sandin Geotechnical and Pavement Applications
(Springer Science and Business Media Deutschland GmbH, 2024) Basayya Balulmath, A.; Sridhar, G.; Saranya, P.
In recent years, industrial recycled and waste materials have been utilized considerably in various civil engineering applications. To aid the metal casting process, metal foundries throughout the world use about 105 million tons of foundry sand annually. When the sand becomes unfit for molding, it is discarded in the landfill as waste foundry sand (WFS). India produces around 3 million tons of foundry sand annually. US Environmental protection Agency (EPA) has estimated that applications of WFS in construction works could prevent 20,000 tons of CO2 emissions and save 200 billion BTU of energy. Sustainable reuse of WFS can furnish an economical and environmentally beneficial solution to conserve landfills and virgin sands. This paper presents a state-of-the-art review of the reuse potentials and engineering properties of WFS as a suitable material in various geotechnical and pavement applications. This study discusses available information on WFS from a geotechnical perspective. Evaluation and characterization of geotechnical behavior and environmental properties of WFS may necessitate its effective utilization in the construction industry. Some existing recovery processes of WFS and its uses are also discussed. Large-scale application of WFS in various civil engineering works may significantly reduce the quantity of waste generated in the state. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Comparative Study of Settlement Performance of Stone Column and Vertical Drains: A Review
(Springer Science and Business Media Deutschland GmbH, 2025) Kapile, P.; Sridhar, G.
The process of building stone columns through weak soils, specifically soft and ultra-soft clays, is known as â€œvibro replacement.â€ An integrated foundation support system with reduced compressibility and enhanced load bearing capacity is formed by the stone column and the intervening soil. Stone columns in cohesive soils easily discharge excess pore water pressure, causing settlement to occur more rapidly than in clay without stone columns. Literature has shown that stone column has the tendency to bulge due to less in-situ lateral stress of soil which results in reduced effectiveness and increased settlement of stone column. Surcharging, a prevalent preloading method for strengthening weak ground, involves applying additional load through soil embankments. In the context of ground improvement, surcharge preloading is commonly used. Prefabricated vertical drains play a crucial role in expediting the consolidation process of soft clay deposits when employing preloading as a ground improvement technique. This paper presents a critical review of the settlement performance of stone column and preloading with prefabricated vertical drains as it is of utmost importance in ground improvement works. A case study comparing the settlement performance of stone column and preloading with prefabricated vertical drains revealed that latter technique is more suitable for extremely soft soil. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
Critical Review and Finite Element Analysis of Smear Zone in Soft Clay Improved by Prefabricated Vertical Drains
(Springer Science and Business Media Deutschland GmbH, 2025) Mahesh, D.; Sridhar, G.
Structures built on soft soils are often affected by settlement problems. Over the past decades, one of the best methods to accelerate the consolidation process is preloading technique with pre-fabricated vertical drains. However, while installing these drains the soil around the drain gets disturbed, which in turn reduces the permeability of soil in radial direction. This disturbance is known to be smear effect and the region of this disturbed soil is the smear zone. This paper presents a state-art-of-the review on analytical, laboratory, field and numerical studies on the smear zone behaviour. Pore pressure variation, water content and permeability in the smear and undisturbed zone are compared. Finite element modeling carried out for better understanding of consolidation behaviour of soft clay improved with PVD is also presented in this paper. The effect of smear is considered in the finite element model and the results from the finite element model are compared with laboratory test results. The soil behaviour is modelled using the modified cam-clay model and the ABAQUS finite element application is used for numerical modelling. Based on the results, the time-settlement data and pore pressure dissipation predicted by the numerical model were comparable with the laboratory results reported in the literature with a variation of upto 10%. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
Finite Element Modelling of Foundation on Soft Clay Improved by Geocell and Boulder-Sand Layer: A Comparative Study
(Springer Science and Business Media Deutschland GmbH, 2025) Rao, M.S.; Sridhar, G.
Rapid infrastructure development urges for sufficient competent ground, which is currently scarce. Thus, the major focus of geotechnical engineers is the development of techniques for improving poor soil. A variety of strategies are used to reduce post-construction settlement, increase the shear strength of the soil, enhance the bearing capacity of the soil system, and improve the stability of superstructures. Among these, soil replacement is the simplest and most widely used method, while geocell reinforcement has been found to be an effective methodology. The three-dimensional structure of geocell provides better lateral confinement to the infill soil, improving its ability to support loads. However, because of its intricate honeycomb structure, numerical modelling of geocell has always proven difficult. Thus, an attempt has been made to generate a three-dimensional model of geocell using PLAXIS 3D. Finite element model was validated using laboratory model test results. A numerical analysis of footing resting over unimproved soft soil and soft soil improved by boulder-sand replacement and geocell reinforcement has been carried out. It was found that by replacement and reinforcement techniques, the performance of the footing can be doubled. The influence of width and depth of the boulder-sand layer and depth of the first geocell layer on bearing capacity improvement has been studied. The effect of the depth of boulder-sand bed on the influence factor was found to be higher compared to the effect of width. Maximum improvement by the inclusion of geocell was observed when it was placed in the middle of the sand layer with an improvement factor of 2.25. Further, using soil investigation data from in situ and laboratory tests, the concept has been extended to a field problem. Â© Deep Foundations Institute 2025.
Influence of type of drainage boundary on coefficient of horizontal consolidation
(ICE Publishing, 2023) Sridhar, G.; Robinson, R.G.; Rajagopal, K.
Vertical drains are used widely to accelerate the consolidation of soft clay deposits when preloading is used as a ground improvement technique. One of the essential input parameters required in Barron's theory is the coefficient of horizontal consolidation, ch. The values of ch can be determined by the radial consolidation test, using either a central sand drain or a porous plastic peripheral drain. This paper presents the laboratory tests carried out to understand the reason for the difference in values of ch determined from inward and outward radial flow consolidations tests. A 150 mm wide instrumented consolidation cell was used to carry out the inward or outward radial consolidation tests. The total stress measurements during consolidation showed non-uniform stress distribution in clay with higher effective stress values close to the drainage boundary. This stiffening of the clay close to the drain retards the consolidation rate resulting in reduced values of ch. As a result, the ch values determined by radially outward consolidation tests with a larger drainage boundary area are lower to those obtained by inward radial flow tests. The pore water pressure measurements showed significantly higher undissipated pore water pressure away from the drainage boundary for the outward flow tests. © 2023 Emerald Publishing Limited: All rights reserved.
Response of Offshore Wind Turbine Monopile Foundation Under Action of Wind Load and Sea Waves: Numerical Analysis
(Springer Science and Business Media Deutschland GmbH, 2025) Sah, B.; Sridhar, G.
Offshore wind turbine, being one of the most important renewable energy sources globally, has witnessed the construction of numerous offshore wind farms. These are established in offshore areas due to the steadier and stronger winds compared to onshore environments. Among the diverse fixed offshore foundation systems utilized for wind turbines including gravity, caisson, tripod, monopile, jacket, and suction, the monopile foundation emerges as the predominant choice, especially well-suited for sea beds with depths up to 35Â m. However, understanding the behavior of monopile foundations under the combined influence of cyclic wind and sea waves remains limited. Throughout the 25 year lifespan of a turbine, cyclic loading continuously affects the foundation, potentially altering soil stiffness and system frequencies. To address this issue, numerical modeling using finite element method program is employed in this study. Through cyclic loading simulations, the response of monopile foundations to wind and sea waves is thoroughly investigated. Parametric studies also conducted to explore the impact of factors such as soil properties and loading conditions. The findings of this study contribute to a deeper understanding of monopile foundation behavior under dynamic environmental conditions, offering valuable insights for design and optimization of offshore wind energy projects. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.