• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.3-11
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• 2005

The structural analysis considering the soil-structure interaction is very important in the design process of underground structures located on the site with various soil conditions. In practice, simplified modelling techniques to obtain the approximate solution are used in accordance with the specifications. However, their details are insufficient for practical engineers to obtain the stable solutions and the analysis results of each engineer occasionally my be different in spite of the same problem. In this study, the sensitivity of structural behaviour on the underground structures is analyzed according to the structural modelling techniques of existing specifications. It is performed to obtain the fundamental informations to establish the guide to obtain the stable solutions in practical analysis of the underground structures such as subway structures.

• Advances in environmental research
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• 제3권2호
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• pp.117-129
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• 2014

Groundwater contamination is seeking a lot of attention due to constant degradation of water by landfills and waste lagoons. In many cases heterogeneous soil system is encountered and hence, a finite element model is developed to solve the advection-dispersion equation for layered soil system as FEM is a robust tool for modelling problems of heterogeneity and complex geometries. Recently developed Meshfree methods have advantage of eliminating the mesh and construct approximate solutions and are observed that they perform effectively as compared to conventional FEM. In the present study, both FEM and Meshfree method are used to simulate phenomenon of contaminant transport in one dimension. The results obtained are agreeing with the values in literature and hence the model is further used for predicting the transport of contaminants. Parametric study is done by changing the dispersion coefficient, average velocity, geochemical reactions, height of leachate and height of liner for obtaining suitability.

• Coupled systems mechanics
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• 제12권5호
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• pp.461-479
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• 2023

The paper deals with the finite element modelling of the free vibration and structural behavior of a particular four-floor reinforced concrete structure subjected to static equivalent seismic loads and supported by a shallow foundation system called SNSF (Spider Net System Footing). The two FE models are a simple 2D Matlab model and a detailed 3D model based on solid elastic elements using Altairworks (Hypermesh and Optistruct). Both models can simulate the soil structure interaction. We concentrate on the behavior of a representative cell involving two columns on five levels. The influence of the boundary conditions on the external vertical planes of the domain are duly studied. The Matlab model appears relevant for a primary estimation of frequencies and stiffness of the whole structure under vertical and lateral loads.

• Geomechanics and Engineering
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• 제2권1호
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• pp.1-18
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• 2010

The analysis of structure response and design of buried structures subjected to dynamic destructive loads have been receiving increasing interest due to recent severe damage caused by strong earthquakes and terrorist attacks. For a comprehensive design of buried structures subjected to blast loads to be conducted, the whole system behaviour including simulation of the explosion, propagation of shock waves through the soil medium, the interaction of the soil with the buried structure and the structure response needs to be simulated in a single model. Such a model will enable more realistic simulation of the fundamental physical behaviour. This paper presents a complete model simulating the whole system using the finite element package ABAQUS/Explicit. The Arbitrary Lagrange Euler Coupling formulation is used to model the explosive charge and the soil region near the explosion to eliminate the distortion of the mesh under high deformation, while the conventional finite element method is used to model the rest of the system. The elasto-plastic Drucker-Prager Cap model is used to model the soil behaviour. The explosion process is simulated using the Jones-Wilkens-Lee equation of state. The Concrete Damage Plasticity model is used to simulate the behaviour of concrete with the reinforcement considered as an elasto-plastic material. The contact interface between soil and structure is simulated using the general Mohr-Coulomb friction concept, which allows for sliding, separation and rebound between the buried structure surface and the surrounding soil. The behaviour of the whole system is evaluated using a numerical example which shows that the proposed model is capable of producing a realistic simulation of the physical system behaviour in a smooth numerical process.

• Geomechanics and Engineering
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• 제11권1호
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• pp.1-39
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• 2016

The finite element method (FEM), discrete element method (DEM), and Discontinuous deformation analysis (DDA) are among the standard numerical techniques applied in computational geo-mechanics. However, in some cases there no possibility for modelling by traditional finite analytical techniques or other mesh-based techniques. The solution presented in the current study as a completely Lagrangian and mesh-free technique is smoothed particle hydrodynamics (SPH). This method was basically applied for simulation of fluid flow by dividing the fluid into several particles. However, several researchers attempted to simulate soil-water interaction, landslides, and failure of soil by SPH method. In fact, this method is able to deal with behavior and interaction of different states of materials (liquid and solid) and multiphase soil models and their large deformations. Soil indicates different behaviors when interacting with water, structure, instrumentations, or different layers. Thus, study into these interactions using the mesh based grids has been facilitated by mesh-less SPH technique in this work. It has been revealed that the fast development, computational sophistication, and emerge of mesh-less particle modeling techniques offer solutions for problems which are not modeled by the traditional mesh-based techniques. Also it has been found that the smoothed particle hydrodynamic provides advanced techniques for simulation of soil materials as compared to the current traditional numerical methods. Besides, findings indicate that the advantages of applying this method are its high power, simplicity of concept, relative simplicity in combination of modern physics, and particularly its potential in study of large deformations and failures.

• 한국작물학회지
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• 제51권4호
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• pp.362-368
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• 2006

A pot experiment was conducted to investigate the effects of soil burial depth on seedling emergences of rice (Oryza sativa) and Echinochloa spp. and to model such effects for mathematical prediction of seedling emergences. When the Gompertz curve was fitted at each soil depth, the parameter C decreased in a logistic form with increasing soil depth, while the parameter M increased in an exponential form and the parameter B appeared to be constant. The Gompertz curve was combined by incorporating the logistic model for the parameter C, the exponential model for the parameter M, and the constant for the parameter B. This combined model well described seedling emergence of rice and Echinochloa species as influenced by soil burial depth and predicted seedling emergence at a given time after sowing and a soil burial depth. Thus, the combined model can be used to simulate seedling emergence of crop sown in different soil depths and weeds present in various soil depths.

• 한국토양환경학회지
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• 제5권1호
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• pp.25-32
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• 2000

동전기적 제염 장치를 제작하여 $Sr^{2+}$ 으로 오염된 Kaolin Clay토양을 제염하여 제염후의 셀토양 내의 잔류 농도를 XRF로 측정하여 동전기적 방법에 의한 제염효율을 분석했다. 또한, 이 동전기적 토양제염을 모델링하기 위해 새로운 수치모델을 개발하였고 이 모델에 의한 예측값과 제염실험값을 서로 비교하여 개발한 수치모델을 검증했다. 한편 셀 가장자리에 위치한 전극의 전위차를 높이며 전위차에 따른 토양제염 특성을 분석했다. 동전기적 제염 장치에 의한 오염토양의 제염결과 3일 경과 후 40V하에서 실험셀 앞부분 토양 내의 $Sr^{2+}$은 거의 제염되었고 중간부분은 제염비율의 변화가 거리에 따라 매우 심하게 나타났다. 그러나 뒷부분은 거의 제염되지 않았다. 그래서 셀토양 내의 $Sr^{2+}$의 총제염 비율은 약 42.6% 였다. 제염실험 6일 경과후 셀토양 내의 총제염 비율은 약 84.8% 였다. 또한, 개발된 수치 모델에 의한 예측치는 제염실험값과 상당한 일치를 보였다. 한편 셀 가장자리에 위치한 전극의 전위차를 10V, 20V, 40V로 높이며 토양제염 특성을 분석한 곁과 총제거율은 전위차가 높아짐에 따라 약 21.9%, 43.3%, 84.8%로 높아지는 것으로 나타났다.

• 한국지반공학회논문집
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• 제31권1호
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• pp.25-35
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• 2015

서남해안 지역의 중간조밀한 실트질모래 지반에서 버켓기초 스커트벽체의 압입저항력을 원심모형실험을 통하여 분석하였다. 압입저항력은 석션을 작용하지 않고 버켓기초를 지반에 관입시킬 때 발생하는 저항력으로서 자중관입 깊이와 직접적으로 관계된다. 스커트벽체의 주면저항력에 의한 지반의 응력증가 효과를 고려하는 방법(Houlsby and Byrne, 2005) 을 기반으로 실험 결과와 유사한 압입저항력을 산정할 수 있었다. 압입저항력 산정에 이용되는 수평토압계수, 스커트 벽체와 지반간의 경계면 마찰각 등의 주요 물성값의 산정 방법에 대하여 기술하였다. 또한, 응력증가 효과의 고려 여부와 물성값의 변화가 압입저항력 산정 결과에 미치는 영향과 실험을 통해 계측된 압입시 지반거동에 대하여 분석하였다.

• 지질공학
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• 제29권4호
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• pp.383-391
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• 2019

Bio-grouting based on microbial-induced calcite precipitation (MICP) is recently emerging as a novel and environmentally friendly technique for improvement of coarse-grained ground. To date, the mechanical behaviour of bio-grouted coarse-grained soil with different calcite contents and grain sizes still remains poorly understood. The primary objective of this study is to investigate the influence of calcite content on the mechanical properties of bio-grouted coarse-grained soil with different grain sizes. This is achieved through an integrated study of uniaxial loading experiments of bio-grouted coarse-grained soil, 3D digitization of the grains in conjunction with discrete element modelling (DEM). In the DEM model, aggregates were represented by clump logic based on the 3D morphology digitization of the typical coarse-grained aggregates while the CaCO₃ was represented by small-sized bonded particle model. The computed stress-strain relations and failure patterns of the bio-grouted coarse-grained soil were validated against the measured results. Both experimental and numerical investigation suggest that aggregate sizes and calcite content significantly influence the mechanical behaviour of bio-cemented aggregates. The strength of the bio-grouted coarse-grained soil increases linearly with calcite content, but decreases non-linearly with the increasing particle size for all calcite contents. The experimental-based DEM approach developed in this study also offers an optional avenue for the exploring of micro-mechanisms contributing to the mechanical response of bio-grouted coarse-grained soils.

• Geomechanics and Engineering
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• 제17권1호
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• pp.31-45
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• 2019

In this study the spatial variability of soils is substantiated physically and numerically by using random field theory. Heterogeneous samples are fabricated by combining nine homogeneous soil clusters that are assumed to be elements of an adopted random field. Homogeneous soils are prepared by mixing different percentages of kaolin and bentonite at water contents equivalent to their respective liquid limits. Comprehensive characteristic laboratory tests were carried out before embarking on direct shear experiments to deduce the basic correlations and properties of nine homogeneous soil clusters that serve to reconstitute the heterogeneous samples. The tests consist of Atterberg limits, and Oedometric and unconfined compression tests. The undrained shear strength of nine soil clusters were measured by the unconfined compression test data, and then correlations were made between the water content and the strength and stiffness of soil samples with different consistency limits. The direct shear strength of heterogeneous samples of different stochastic properties was then evaluated by physical and numerical modelling using FISH code programming in finite difference software of $FLAC^{3D}$. The results of the experimental and stochastic numerical analyses were then compared. The deviation of numerical simulations from direct shear load-displacement profiles taken from different sources were discussed, potential sources of error was introduced and elaborated. This study was primarily to explain the mathematical and physical procedures of sample preparation in stochastic soil mechanics. It can be extended to different problems and applications in geotechnical engineering discipline to take in to account the variability of strength and deformation parameters.