• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.39-47
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• 1985

In this paper, a FEM analysis model was developed to solve the consolidation phenomena of embankment on the soft foundation. The developed FEM model was based on the Biot's consolidation equation which was coupled with one of three stress-strain constitutive relationships. In order to check the validity of the newly developed FEM model, the program input data were used by a test embankment which had been already constructed at Cubzac-les-ponts in France by Magnan et al. The FEM results compared to the experimental and analytical results which were obtained by the Magnan's group at Cubzac-les-ponts. The results compared showed that the consolidation phenomena were well explained by the author's FEM model which results were more accurate than the others. As for the pore water pressure, Christian-Boehmer's method used in this paper was considered preferable to Sandhu-Wilson's used by Magnan.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.425-432
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• 2020

The appearance of Korean traditional roof tiles is beautiful and excellent in water resistance, fire resistance and durability, but a high sintering temperature of 1,200℃ or higher is required. Therefore, due to the economical and heavy weight problem, the current trend is to use different roof finishing materials than Korean traditional roof tiles. By adding nanoaluminosilicate to clay and kaolin, which are the materials of the clay roof tiles, the sintering temperature is sintered at a low temperature of 1,000℃ or less, and the optimal mixing and material process is designed to satisfy the characteristics required as a Korean traditional roof tile. The results of this study again demonstrate the superiority of Korean traditional tiles with roof finishing materials using nanoaluminate. The properties of Korean traditional roof tiles that satisfy the criteria of KS F 3510 by applying fire resistance of natural minerals and nanoparticle technology to flexural strength of 2800N, Bulk specific gravity of 2.0g/㎤ and absorption rate of less than 10.0%, through which and researched materials development.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.175-182
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• 2023

In general, the design of structures and its construction processes are fundamentally dependent on their foundation and supporting ground. Thus, it is imperative to understand the behavior of the soil under certain stress and drainage conditions. As it is well known that certain characteristics and behaviors of soils with fines are highly dependent on water content, it is critical to accurately measure and identify the status of the soils in terms of water contents. Liquid limit is one of the important soil index properties to define such characteristics. However, liquid limit measurement can be affected by the proficiency of the operator. On the other hand, dynamic properties of soils are also necessary in many different applications and current testing methods often require special equipment in the laboratory, which is often expensive and sensitive to test conditions. In order to address these concerns and advance the state of the art, this study explores a novel method to determine the liquid limit of cohesive soil by employing video-based vibration analysis. In this research, the modal characteristics of cohesive soil columns are extracted from videos by utilizing phase-based motion estimation. By utilizing the proposed method that analyzes the optical flow in every pixel of the series of frames that effectively represents the motion of corresponding points of the soil specimen, the vibration characteristics of the entire soil specimen could be assessed in a non-contact and non-destructive manner. The experimental investigation results compared with the liquid limit determined by the standard method verify that the proposed method reliably and straightforwardly identifies the liquid limit of clay. It is envisioned that the proposed approach could be applied to measuring liquid limit of soil in practical field, entertaining its simple implementation that only requires a digital camera or even a smartphone without the need for special equipment that may be subject to the proficiency of the operator.

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.17-28
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• 2009

When embankments are constructed on soft clay deposit, unsymmetrical surcharges due to embankments may generate the excessive vertical settlement and lateral deformation of soft clay foundation. The excessive deformations in soft grounds cause not only stability problem of the embankment itself but also that of the adjacent structures. The objectives of this research are to study the deformational behavior of soft ground due to the embankment load with different loading and soil conditions. Five model tests are carried out with different test conditions. From the results of the model tests, it is concluded that the lateral displacement induced by the embankment load occurs in the range of two times of the embankment width from a toe. In addition, the relationship between loading rate, v, and the vertical settlement of the soft ground, ${\Delta}s$, and the lateral displacement at the toe of embankment, ${\Delta}y_m$, is investigated based on the model test results.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.33-40
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• 2008

This paper describes the performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area composed of soft marine clay with high water content and high compressibility. From field monitoring results, excessive ground settlement compared with predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared with field monitoring results after additional surcharge was applied. It might be used for verification of recalculated results.

• Advances in concrete construction
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• v.17 no.2
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• pp.111-126
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• 2024

During the clinkering stages of cement production, the chemical composition of fine raw materials such as limestone and clay, which include iron oxide (Fe₂O₃), silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃), significantly influences the quality of the final product. Specifically, the chemical interaction of Fe₂O₃ with CaO, SiO₂ and Al₂O₃ during clinkerisation plays a key role in determining the chemical reactivity and overall quality of the final cement, shaping the properties of the concrete produced. As an extension, this study aims to investigate the physical effects of incorporating nanosized Fe₂O₃ particles as fillers in concrete matrices, and their impact on concrete structures, namely slabs. To accurately model the reinforced concrete (RC) slabs, a refined trigonometric shear deformation theory (RTSDT) is used. Additionally, the stochastic Eshelby's homogenization approach is employed to determine the thermoelastic properties of nano-Fe₂O₃ infused concrete slabs. To ensure comprehensive coverage in the study, the RC slabs undergo various mechanical loads and are exposed to temperature fields to assess their thermo-mechanical performance. Furthermore, the slabs are assumed to rest on a three-parameter viscoelastic foundation, comprising the Winkler elastic springs, Pasternak shear layer and a damping parameter. The equilibrium governing equations of the system are derived using the principle of virtual work and subsequently solved using Navier's technique. The findings indicate that while ferric oxide nanoparticles enhance the mechanical properties of concrete against mechanical loading, they have less favorable effects on its performance against thermal exposure. However, the viscoelastic foundation contributes to mitigating these effects, improving the concrete's overall performance in both scenarios. These results highlight the trade-offs between mechanical and thermal performance when using Fe₂O₃ nanoparticles in concrete and underscore the importance of optimizing nanoparticle content and loading conditions to improve the structural performance of concrete structures.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.149-160
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• 2008

Offshore pile foundations are prone to lateral soil pressures resulting from embankment construction for the reclamation on deepwater soft clay. Since the 1990s, offshore reclamation has actively progressed in Korea, connecting with the development of Songdo newtown, Incheon newport, and Busan newport representatively. Special attention has been given to lateral soil-structure interaction problems related to passively-loaded offshore pile foundations. Based on a plane strain large deformation finite element (LDFE) approach, this paper presents the results of investigation into undrained (short-term) and drained (long-term) behavior of passively-loaded offshore pile foundations. This study examines the effects of major factors, such as soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. The results allowed quantification of differences in the magnitude of lateral soil pressure acting on the piles between undrained and drained phases.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.99-114
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• 2005

In Part I of this paper, a conceptual approach of the stress path method was newly proposed for a rational estimation of settlements of saturated clay deposits. A detailed procedure for effective evaluation and use of settlement-related characteristic deformation behaviors was developed in order to provide practicality to the new approach. In this Part II, on the basis of the results of Part 1, the concept of the new approach was embodied in the form of a detailed settlement estimation procedure. The applicability and usefulness of the new procedure were strongly supported by various application examples. In addition, possible errors of other conventional settlement estimation methods were investigated by comparing with the new procedure. Because of its flexible applicability for wide range of field conditions, the new procedure will have great usefulness in the practical side. For example, a reasonable foundation design based on allowable settlement criteria can be easily performed and modification of design factors can be readily reflected even during the subsequent construction stage. Especially, the new procedure will be of great use for preliminary work in a large scale construction site where various structures are planned to be constructed on a nearly identical ground condition.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.711-719
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• 2006

A series of geotechnical centrifuge model tests and numerical modelling have been performed to study engineering characteristics of the composite ground reinforced by both the Sand Compaction Piles(SCPs) and the deformation-reducing sheet piles. The research has covered several key issues such as the load-settlement relation, the stress concentration ratio and the final water content of the ground Totally three centrifuge tests have been conducted by changing configuration of the sheet piles, i.e., a test without the sheet pile, a test with the sheet pile at a single side and a test with the sheet piles at the both sides. In the model tests, a vertical load was applied in-flight on the ground surface. On the other hand, class-C type numerical modelling has been performed by using the SAGE-CRISP to compare the centrifuge test results using an elasto-plastic model for SCPs and the Modified Cam Clay model for the soft clay. It has been found that the sheet piles can restraint failure of foundation, thereby increasing yield stress of the ground. The stress concentration ratio was in the range of $2{\sim}4$. In addition, numerical analysis results showed reductions both in the ground heave($20{\sim}30%$) and in the horizontal movement($28{\sim}43%$), demonstrating the deformation-reducing effect of the sheet piles.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.349-356
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• 1999

In general, the term soft ground includes clayey soils, which have large compressibility and small shear resistance due to the external load. All process of consolidation in compressible soils can be explained in terms of a transfer of load from an incompressible pore-water to a compressible soil structure. Therefore, one of the most important subjects about the characteristics of the time-dependent consolidation of the clay foundation by the change of load may be the presumption of the final settlement caused by consolidation and the degree of consolidation according to the time. The problems of discontinuous layer interface are very important in the algorithm and programming for the analysis of multi-layered soils using a numerical analysis, finite difference method. Better results can be obtained by the Process for discontinuous layer interface, since it can help consolidation analysis to model the actual ground. The purpose of this paper Provides an efficient computer algorithm based on numerical analysis using finite difference method(F.D.M.) which account for multi-layered soils to determine the degree of consolidation and excess pore pressures relative to time and positions more realistically.