• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.499-502
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• 2003

The purpose of this study is to understand the sliding characteristics of the infilling-joint surface using the new devised shear test apparatus with changeable slope for the original infilling materials and the infilling materials experienced cyclic freezing-thawing processes. Three types of the mother rock classified as the igneous rock, the metamorphic rock and the sedimentary rock and the infilling materials were collected for laboratory test. The cohesion according to the slope change of the rock joint shows large variation within ${\pm}$5 degrees but the internal friction angle shows appears the linear decreasing tendency. It is confirmed that the affecting factor of slope change of rock joint at the behavior of rock mass is larger than that of the infilling thickness. Test results show that the cohesion and the internal friction angle in 100 times of cyclic freezing-thawing processes are decreased about 50 percent compared with original one. A further study using various infillings materials would lead to a better understanding of the failure mechanism of rock mass by slope change of rock joint.

• 한국전산유체공학회지
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• 제20권2호
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• pp.46-51
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• 2015

In this paper, we have developed numerical model for particulated flow through narrow slit using Eulerian-Granular method. Commercial software (FLUENT) was utilized as simulation tool and main focus was to identify the effect from various numerical options for modeling of solid particles as continuos phase in granular flow. Gidaspow model was chosen as basic model for solid viscosity and drag model. And lun-et-al model was used as solid pressure and radial distribution model, respectively. Several other model options in FLUENT were tested considering the cross related effect. Mass flow rate of the particulate through the slit was measured to compare. Due to the high volume density of the stacked particulates above the slit, effect from various numerical options were not significant. The numerical results from basic model were also compared with experimental results and showed very good agreement. The effects from the characteristics of particles such as diameter, angle of internal friction, and collision coefficient were also analyzed for future design of velocity resistance layer in solar thermal absorber. Angle of internal friction was found to be the dominat variable for the particle mass flow rate considerably. More defined 3D model along with energy equation for complete solar thermal absorber design is currently underway.

• 한국농공학회논문집
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• 제57권3호
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• pp.93-100
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• 2015

The object of this paper is to study the shear characteristics of the weathered granite soil. To this end, a series of consolidated undrained triaxial compression tests are carried out to investigate the shear parameters-cohesion and internal friction angle-for the degree of saturation and degree of weathering. From the results, it is found that the shear parameters of weathered granite soil are influenced on the degree of saturation, degree of weathering and disturbance. Especially, internal friction angle is more influenced on the upper factors than cohesion. And shear parameters are more acted on the degree of saturation than the degree of weathering in the test range. It is, therefore, recommended that must be considered the conditions of granite soil-degree of saturation, degree of weathering and disturbance etc-in case of the calculation of bearing capacity, stability analysis and other designs with shear parameters.

• Geomechanics and Engineering
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• 제13권4호
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• pp.701-714
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• 2017

The effect of nearby cohesionless sloping ground on the uplift capacity of horizontal strip plate anchor embedded in sand deposit with horizontal ground surface has been studied numerically. The numerical analysis has been carried out by using the lower bound theorem of limit analysis with finite elements and linear optimization. The results have been presented in the form of non-dimensional uplift capacity factor of anchor plate by changing its distance from the slope crest for different slope angles, embedment ratios and angles of soil internal friction. It has been found that the decrease in horizontal distance between the edge of the anchor plate and the slope crest causes a continuous decrease in uplift capacity of anchor plate. The optimum distance is that distance between slope crest and anchor plate below which uplift capacity of an anchor plate has been found to decrease with a decrease in normalized crest distance from the anchor plate in presence of nearby sloping ground. The normalized optimum distance between the slope crest and the anchor plate has been found to increase with an increase in slope angle, embedment ratio and soil internal friction angle.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.239-246
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• 2000

It has been generally much fine contents in West Coast of Korea. When cyclic shear stress causing liquefaction was estimated as using cyclic triaxial tests in these grounds, it didn't appear linear relations between deviator stress and confining stress where σ'₃ was more than 150 kpa. Namely, due to no normalization of cyclic shear stress ratio, the errors of this is increased. Therefore, more confining stress is increased, more increment of deviator stress is decreased. So, using linear relations between tanø'/sub d/ of dynamic internal friction angle and CSR where σ'₃ was less than 150 kpa, liquefaction of these grounds was evaluated. Also, as doing detail evaluation which had carried response analysis of earthquake, this appeared good results which was well compatible with empirical methods using N-value of SPT. It was thought that these result evaluated vulnerable liquefaction area more correct than existing methods. Also, characteristics of liquefaction in West Coast grounds was compared with clean sands, with analysis of behavior of pore pressure ratio and axial strain affected by fine contents, as cyclic loading was applied.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.862-870
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• 2010

This thesis has been researched on optimized design method for the total cross section of embankment considering the fact that the size of embankment cross section is directly related with economic efficiency when dam designing. In general, embankment cross section of fill dam is either determined by cohesion and angle of internal friction, a strength parameter of embankment materials or by permeability of embankment. Therefore the size of embankment cross section depending on strength parameter of embankment materials was determined by using MIDAS-GTS program through stress-seepage coupled analysis at the time of fill dam design. As a result, determination of embankment cross section was more affected by the size of central core and permeability rather than by slope stability by shear strength and it was revealed that in case of embankment height being over 20m, stability against infiltration and slope action could be secured only when embankment slope is at least over 1:2.5. In addition, it was also revealed that in case of making the size of central core exceeding specification standard, total cross section of embankment could be reduced considerably and at the time of embankment design, adequate size and appropriateness of embankment cross section could be determined with referring the table suggested by this study.

• Geomechanics and Engineering
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• 제20권6호
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• pp.497-503
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• 2020

In the Kingdom of Saudi Arabia, the shallower depth of the earth's crust is composed of loose dune or beach sand with soluble salts. The expansive behavior of salt bearing soil, fluctuation of ground water table and extreme environmental conditions offer a variety of geotechnical problems affecting safety and serviceability of the infrastructure built on it. Despite spending money, time and other resources on repair and rehabilitation, no significant attention is paid to explore the root causes of excessive differential settlement and cracking to these facilities. The scientific solution required to ensure safety and serviceability of the constructed infrastructure is to improve the strength and durability properties of the supporting ground. In this study, shredded plastic is employed as a low cost and locally available additive to improve strength characteristics of the desert sand. The study shows a remarkable increase in the shear strength and normal settlement of the soil. A seven (07) degree increase in angle of internal friction is achieved by adding 0.4 percent of the shredded plastic additive. The effect of different proportions and sizes of the plastic strips is also investigated to obtain optimum values. Such a long-lived solution will seek to reduce maintenance and repair costs of the infrastructure facilities laid on problematic soil along with reduction of environmental pollutants.

• Geomechanics and Engineering
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• 제23권4호
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• pp.301-311
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• 2020

In this study, shear strength behavior of fine-grained soils was investigated under unsaturated conditions. The samples in the unsaturated state were subjected to a net normal stress (σ-u_a) of 40 kPa and different matric suctions (u_a-u_w) of 50, 100 and 150 kPa. The matric suction values applied in the triaxial tests were selected according to the bubbling pressures determined from the SWC curves. The study was carried out on prepared re-constituted cylindrical samples by uniaxial consolidation of soil slurries. First, consolidated drained (CD) triaxial compression tests were performed on the saturated samples and the cohesion and angle of internal friction were determined. After that, drained triaxial compression tests under matric suctions were performed on the unsaturated samples. In order to obtain unsaturated test results, cohesion and internal friction angle values of saturated samples were used. The nonlinear surface representing the shear strength surface was approximated consisting of two planes (double planar surface). The reason for the nonlinear behavior of some soils is that the amount of sand content contained in it is relatively high and the bubbling pressure/permanent water content value is relatively low.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.136-145
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• 2009

Factors influencing shear behavior of granular material include particle size, shape, distribution, relative density, particle crushing, etc. In this study, these factors are characterized by viewpoint of shear behavior using numerical analysis based on DEM. Geometrical particle shape is represented by a combination of small circular particles and influence of particle shape on crushing is studied through relative comparisons between clump (uncrushable) and cluster (crushable) models which are modeled using DEM. Also, particle shape is quantified by the dimensionless parameters such as circularity and convexity. The results indicate that particle shape indexes have a negative association with internal friction angle. Also, internal friction angle becomes reduced and failure envelop curve becomes nonlinear due to the particle crushing. It is also found that numerical results are quite good agreement with the experimental test conducted in this study.

• 한국지반공학회지:지반
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• 제9권4호
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• pp.83-92
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• 1993

세 주응력을 서로 독립적으로 조절할 수 있는 입방체형삼축시험기를 이용하여 모래에 대한 일련의 배수삼축시험이 실시되었다. 실험결과 모래의 응력 -변형률거동과 강도는 중간주응력의 크기에 따라 각기 다른 특성을 보이는 것으로 나타났다. 우선 최소주응력이 일정한 상태에서 중간 주응력이 증가함에 따라 파괴시의 축변형률 e1은 감소하는 경향이 있으며 체적팽창현상은 증가 하는 것으로 나타나고 있다. 그리고 내부마찰각은 축차응력비 b가 증가함에 따라 증가하다 b가 1 부근에 접근하면서 약간 감소하는 경향을 보이고 있다. 한편 Mohrfoulomb규준은 모래의 파괴 강도를 과소산정하는 경향을 보이고 있으나 Lade의 파괴규준은 시험치와 좋은 일치를 보이고 있다.