• Geomechanics and Engineering
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• v.28 no.6
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• pp.559-571
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• 2022

Deep soil mixing, DSM technique has been widely used to improve the engineering properties of problematic soils. Due to growing urbanization and the industrial developments, disposal of brick dust poses a big problem and causes environmental problems. This study aims to use brick dust in DSM application in order to minimize the waste in brick industry and to evaluate its effect on the improvement of the geotechnical properties. Three different percentages of cement content: (10, 15 and 20%) were used in the formation of soil-cement mixture. Unlike the other studies in the literature, various percentages of waste brick dust: (10, 20 and 30%) were used as partial replacement of cement in soil-cement mixture. The results indicated that addition of waste brick dust into soil-cement mixture had positive effect on the inherent strength and stiffness of loose sand. Cement replaced by 20% of brick dust gave the best results and reduced the final setting time of cement and resulted in an increase in unconfined compressive strength, modulus of elasticity and resilient modulus of sand mixed with cement and brick dust. The findings were also supported by the microscopic images of the specimens with different percentages of waste brick dust and it was observed that waste brick dust caused an increase in the interlocking between the particles and resulted in an increase in soil strength. Using waste brick dust as a replacement material seems to be promising for improving the geotechnical properties of loose sand.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.33-40
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• 2005

Impact-echo test, a kind of simple and economical method to evaluate the integrity of drilled piles has some limitations to use because the stress wave can be generated only on the head of a pile and the wave propagation in the pile with surrounding soils are very complicated. Numerical analyses and model tests in the laboratory have shown that both the ratio of length to diameter of a pile and the stiffness ratio of pile to soil have influence on the resolution of testing results. Full scale testing piles which have artificial defects were used to verify the capability of impact-echo technique as a tool for the pile integrity evaluation. Behaviour of the reflected signal of stress wave was investigated according to the type of defects. Elastic modulus of the pile was calculated using the wave velocity in the pile and the unconfined strength of concrete specimen. Influences of the stiffness difference between the pile and the ground on the characteristics of a wave signal were also examined.

• Structural Engineering and Mechanics
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• v.36 no.4
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• pp.499-511
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• 2010

This paper examines the ice cover effects on the seismic response of concrete gravity dam-reservoir-foundation interaction systems subjected to a horizontal earthquake ground motion. ANSYS program is used for finite element modeling and analyzing the ice-dam-reservoir-foundation interaction system. The ice-dam-reservoir interaction system is considered by using the Lagrangian (displacementbased) fluid and solid-quadrilateral-isoparametric finite elements. The Sariyar concrete gravity dam in Turkey is selected as a numerical application. The east-west component of Erzincan earthquake, which occurred on 13 March 1992 in Erzincan, Turkey, is selected for the earthquake analysis of the dam. Dynamic analyses of the dam-reservoir-foundation interaction system are performed with and without ice cover separately. Parametric studies are done to show the effects of the variation of the length, thickness, elasticity modulus and density of the ice-cover on the seismic response of the dam. It is observed that the variations of the length, thickness, and elasticity modulus of the ice-cover influence the displacements and stresses of the coupled system considerably. Also, the variation of the density of the ice-cover cannot produce important effects on the seismic response of the dam.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.831-838
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• 2004

To study on mechanical characteristics of weathered granite masses are difficult because of undisturbanced sampling and in-situ test. Generally, pressuremeter test is widely used to investigate the behavior of weathered rock masses. However, it has many problems to get a limit pressure because of cavity collapse, membrane damage, ete. This study aims to evaluate the mechanical characteristics of weathered granite masses using in-situ pressuremeter test and numerical analysis depending on the ratio of length and diameter of the membrane(L/D=5, 8, 10, 15, 20). Test results and data are shown that strength parameters are reduced exponentially varing weathering degree, and numerical analysis results are approximately coincided with the test results. And the ratio of length and diameter of the membrane arc not affected the parameters such as modulus of pressuremeter, shear modulus, etc. But limit pressure is increased decreasing membrane length based on numerical analysis. On the other hand, increasing the membrane length, yield pressure is decreased and plastic radius is increased in the case of same weathering degree.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.55-64
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• 2010

Since various weathered soils are encountered in many domestic construction sites, it is necessary to estimate characteristics of natural weathered soils. However, the remolded sample of weathered soils are commonly used to estimate their characteristics because it is very difficult to sample weathered soils in undisturbed states. However, it is well known that the behavior of remolded sample is different from that of the undisturbed sample particularly in the dynamic response, because the particle structure of undisturbed sample maintains its original structure from the mother rock. Thus, to evaluate the influence of sampling method and preparation method on stress-strain behavior, the resonant column tests were performed on the block, tube samples, remolded samples with static compression and remolded samples with tamping of the weathered granite soils. The shear modulus of the remolded sample with tamping is larger than the other samples presumably due to the high tamping pressure enough to induce particle breakage. The tube samples show larger damping ratios than other samples. Furthermore, one-dimensional ground response analysis was performed to compare the results qualitatively.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.170-180
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• 2008

Successful design, construction and maintenance of NATM tunnel demands prediction, control, stability guidelines, the estimation pre-improvement support system and monitoring of surface settlement, gradient and ground displacement with high accuracy. Moreover, urban NATM tunnel under difficult geotechnical conditions is important the estimation and necessary of pre-improvement support system. Various strategies have been proposed for the quantitative estimation of pre-improvement support system. This paper was investigated and analysed an assessment technique for the quantitative estimation of pre-improvement support system on underground space, as mountain and urban tunnel, in detail. The analysis performed on design and construction stage with field database using the proposed stability estimation index by many researcher including the critical strain and the apparent Young's modulus concept.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.617-624
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• 2006

Site response analysis is widely used in estimating local seismic site effects. The soil behavior in the analysis is assumed to be Independent of the rate of the seismic loading laboratory results, however, indicate that cohesive soil behavior is greatly influenced by the rate of loading. A new equivalent linear analysis method is developed that accounts for the rate-dependence of soil behavior and used to perform a series of one dimensional site response analyses. Results indicate that while rate-dependent shear modulus has limited influence on computed site response, rate-dependent soil damping greatly filters out high frequency components of the ground motion and thus results in lower response.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.103-111
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• 2008

This study proposes a technique to estimate the material property of a paper by using an experimental methods and commercial CAE software. Under gravitation, if one side of the paper is attached to the ground, the opposite side of paper is largely deformed, and vibrates freely. Since the paper has an orthotropic characteristic due to its treatment, the deformations in two orthogonal directions of the dry paper are different. An experimental method to measure the static deformation of the paper introduces this phenomenon. And dynamic behavior, frequency of free vibration is measured. And then. virtual prototypes that can represent the static and dynamic behavior are modeled by using the commercial CAE software $RecurDyn^{MT}$/MTT3D, which has been widely used by the printer makers. While comparing the deformation and frequency from the experiment and simulation, a design optimization technique in the commercial CAE software of R-INOPL, $RecurDyn^{TM}$/AutoDesign is used to estimate the material property such as Young's modulus, shear modulus and density of the paper.

• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.5-15
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• 2005

A large diameter sampler that can take undisturbed samples from soft ground was developed by KICT. In order to compare the quality of samples taken by the sampler with those of the traditional piston sampler, a series of laboratory tests were performed. Samples were taken at different sites such as Incheon, Gimhae, Yangsan and Busan. The results showed that the values of unconfined compression strength, secant modulus, pre-consolidation pressure, undrained shear strength, and shear modulus exhibited higher in samples taken by the large scale sampler. Strains at shear failure and volumetric strains were low for the new sampler. It was proved from the comparison that better quality samples could be obtained by the KICT sampler.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3052-3060
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• 2013

When planning to construct adjacent structure by the side tunnel, the criteria of safety zone of tunnel have been proposed. There are no specific theoretical basis regarding load conditions and the distance of structure and the geological strata and the conditions of adjacent structure's location, and the conditions applied load. Two and three dimensional numerical analysis preformed to prove the deformation of the ground and structures caused by the tunnel excavation and evaluated the correlation and the suitability of the tunnel's safety zone regarding the location of adjacent structures and the changes in the modulus of deformation. This paper proposed the safety zone's range is getting bigger as the modulus of deformation is higher. Also, it seems that the possible range of construction under constraints in the diagram of revalued safety zone significantly expands as shear failure line appears on the invert extension line below the spring line.