• Tunnel and Underground Space
• /
• v.31 no.6
• /
• pp.593-609
• /
• 2021

We proposed a numerical method for the thermo-mechanical behavior of rock fracture using a grain-based distinct element model (GBDEM) and simulated thermally induced fracture slip. The present study is the benchmark simulation performed as part of DECOVALEX-2023 Task G, which aims to develop a numerical method to estimate the coupled thermo-hydro-mechanical processes within the crystalline rock fracture network. We represented the rock sample as an assembly of Voronoi grains and calculated the interaction of the grains (blocks) and their interfaces (contacts) using a distinct element code, 3DEC. Based on an equivalent continuum approach, the micro-parameters of grains and contacts were determined to reproduce rock as an elastic material. Then, the behavior of the fracture embedded in the rock was characterized by the contacts with Coulomb shear strength and tensile strength. In the benchmark simulation, we quantitatively examined the effects of the boundary stress and thermal stress due to heat conduction on fracture behavior, focusing on the mechanism of thermally induced fracture slip. The simulation results showed that the developed numerical model reasonably reproduced the thermal expansion and thermal stress increment, the fracture stress and displacement and the effect of boundary condition. We expect the numerical model to be enhanced by continuing collaboration and interaction with other research teams of DECOVALEX-2023 Task G and validated in further study experiments.

• Composites Research
• /
• v.30 no.3
• /
• pp.193-201
• /
• 2017

Molecular dynamics simulation and the Mori-Tanaka micromechanics study are performed to investigate the effect of the covalent grafting between CNT and polyester on the mechanical behavior and load transfer of nanocomposites. The transversely isotropic stress-strain curves are determined through the tension and shear simulations according to the covalent grafting. Also, isotropic properties of randomly dispersed nanocomposites are obtained by orientation averaging the transversely isotropic stiffness matrix. By addressing the grafting, the transverse Young's modulus and shear moduli of the nanocomposites are improved, while the longitudinal Young's modulus decreases due to the degradation of the grafted CNT.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.6
• /
• pp.1319-1327
• /
• 1994

Since fatigue cracks in rail can be the source of fractures and subsequent derailments, quantitative evaluation of the fatigue behavior and fracture properities due to the analysis results of laboratory test are drawn on the basis for predicting fatigue life and making a decision of safe inspection interval. Charpy V-notch and fracture toughness behavior were evaluated from the results of Charpy impact test. Fatigue test was performed by using CT type specimen under constant amplitude loading, and finally the effects of the following parameters; crack orientation, temperature, and stress ratio, on the fatigue crack growth behavior were studied.

• Tunnel and Underground Space
• /
• v.21 no.1
• /
• pp.50-65
• /
• 2011

Analysis of correlation and behavior characteristics at elastic wave velocity have studied on Korean rock data after checking population size and Chi-square method. Behavior characteristics are quite different from each rock and mechanical parameters at elastic wave velocity. This study shows it is necessary to analize correlation to rock behavior characteristics for correct answer from natural rock.

• Journal of Biomedical Engineering Research
• /
• v.24 no.4
• /
• pp.329-337
• /
• 2003

Blood in congenital or acquired AY fistula(arteriovenous fistula) flows from arteries directly to veins. detouring peripheral micro-circulation. This makes a great effect on the hemodynamics of human cardiovascular system. In this study, a computational method using lumped parameter mode) was proposed to simulate the cardiovascular hemodynamics of patients with acute AV fistula The cardiovascular system model with a fistula compartment in left lower limb was built using 17 standard lumped compartments. Using fourth order Runge-Kutta method. we solved numerically the unsteady linear set of the ordinary differential equations resulting from application of Kirchhoff's law to the lumped parameter hemodynamic model. The baroreceptor reflex system was implemented to explain the auto-regulation effect of the cardiovascular system with acute AV fistula.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.7
• /
• pp.47-54
• /
• 2009

Better understanding of in-situ mechanical behavior of pavement foundations is very important to predict long-term effects on the system performance of transport infrastructure. For this purpose resilient stiffness characterization of geomaterials is needed to properly adopt such mechanistic analysis under both traffic and environmental loadings. In this paper in-situ monitoring data from KHC test road were used to analyze the non-linear response using finite element method for a selected constitutive model of foundation geomaterials, and the results were compared with the field data.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.3
• /
• pp.152-159
• /
• 2010

Recently, the public interest in eco-friendly material and structure has been increasing and many Hwang-toh researches are being actively performed. Hwang-toh is one of the traditional environment friendly construction materials used as a construction and plastering material. Hwang-toh has many advantages as construction material due to its high heat storage capacity, auto-purification, antibiotic ability, and infrared ray emission characteristics. But, currently it has not been developed into construction material and used in modern construction due to its low strength and dry shrinkage cracking prone characteristics. According to the recent researches and study results, Hwang-toh can be used as a natural pozzolanic material like fly-ash or pozzolan. In this study, mechanical properties and structural flexure behavior experiments of slag, recycled PET fiber, and Hwang-toh added concrete are carried out. The test results showed that drying shrinkage of concrete mixed with Hwang-toh has lower compressive strength and elastic modulus than those of control cement concrete specimen, but it has the similar flexural behavior in reinforced concrete beams.

• Magazine of the Korea Concrete Institute
• /
• v.3 no.2
• /
• pp.77-86
• /
• 1991

철근 콘크리트 부재의 부착거동은 철근 콘크리트 구조물을 역학적 거동을 규명하는데 매우 중요한 요소가 된다. 본 논문에서는 이러한 철근 콘크리트의 부착거동을 서술할 수 있는 이론모델을 유도하여 제시하였다. 본 해석모델은 철근 콘크리트부재의 위치에 따라 다랄지는 국부 부착응력과 부착슬립의 관계를 나타내주고 있으며, 이에 대한 실험결과를 잘 설명하고 있음을 보여주고 있다. 본 부착해석모델은 철근콘크리트 구조물의 좀더 정확한 해석과 설계를 가능케 할 것으로 사료된다.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2000.09a
• /
• pp.105-115
• /
• 2000

As large underground projects such as radioactive waste disposal, hot water and heat storage, and geothermal energy become influential, the study, which consider all aspects of thermics, hydraulics and mechanics would be needed. Thermo Hydro-Mechanical coupling analysis is one of the most complex numerical technique because it should be implemented with the combined three governing equations to analyze the behavior of rock mass. In this study, finite element code, which is based on Biot's consolidation theory, was developed to analyze the thermo-hydro-mechanical coupling in continuum rock mass. To verify the implemented program, one-dimensional consolidation model under the isothermal and non-isothermal conditions was analyzed and was compared with the analytic solution. The parametric study on two-dimensional consolidation was also performed and the effects of several factors such as poisson's ratio and hydraulic anisotropy on rock mass behavior were investigated. In the future, this program would be revised to be used for analysis of general discontinuous media with incorporating discrete joint model.

• Tunnel and Underground Space
• /
• v.10 no.3
• /
• pp.355-365
• /
• 2000

As large underground projects such as radioactive waste disposal, hot water and heat storage, and geothermal energy become influential, the study, which consider all aspects of thermics, hydraulics and mechanics would be needed. Thermo-Hydro-Mechanical coupling analysis is one of the most complex numerical technique because it should be implemented with the combined three governing equations to analyze the behavior of rock mass. In this study, finite element code, which is based on Biot's consolidation theory, was developed to analyze the thermo-hydro-mechanical coupling in continuum rock mass. To verify the implemented program, one-dimensional consolidation model under the isothermal and non-isothermal conditions was analyzed and was compared with the analytic solution. The parametric study on two-dimensional consolidation was also performed and the effects of several factors such as poisson's ratio and hydraulic anisotropy on rock mass behavior were investigated. In the future, this program would be revised to be used for analysis of general discontinuous media with incorporating discrete joint model.