• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.70-79
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• 1999

The lower ground of structure, in which the strip loads, such as earth dams and embankments , are signiificantly working on , is required to be interpreted as a state of plane strain where the strain of intermediated principal stress direction is put '0' . The plane strain state is frquently observed in actural soil engineering case. For those case, drained stress-strain and strength behavior of Iksan weathered granite soil prepared in cubical specimens with cross-anisotropic fabric was studied by conventional triaxial compression, plane strain and cubial triaxial tests with independent control of the three principal stress. All specimens were loaded under conditions of principl stress directions fixed and aligned with the directions of the material axes. As a result of research , when a ground condition is analyzed under plane strain state, the shear strength obtained from the conventional triaxial compression test can be understimated.

• Journal of Industrial Technology
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• v.17
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• pp.119-124
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• 1997

This thesis is an experimental research of shear behavioral characteristics and shear behavioral coefficient of weathered residual soil which is mostly contained in soil of Korea. Using the weathered residual soil from mountain near Kangwon National University, this experimental research were contained the physical properties of sample in term of the basic test method such as specific gravity, plastic and liquid limit, grain-size distribution, density and water content. Experimental results obtained from direct shear test sand triaxial compression tests show that according to step loading, linear strain and linear stress increase continually and angle of internal friction decreases just little according to incresing of water content in case of ignoring the cohesion, and angle of internal friction appears the maximum angle near a optimum moisture content in case of considering the cohesion.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.5
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• pp.132-144
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• 2001

Iln order to figure out criteria of bentonite for using as impervious material of waste landfill, laboratory experiments were performed to reveal the geotechnical properties of soil-bentonite mixtures such as compaction test, direct shear test, unconfined compression test, triaxial compression test, consolidation test and permeability test. The results of the study are summarized as follows ; 1. Based on the compaction test, optimum moisture content increased with the increase of bentonite content, but maximum dry density decreased. 2. In unconfined compression test, the maximum strength of the soil-bentonite mixtures appeared at 10% bentonite content. The correlation equation between stress($\sigma$) and strain($\varepsilon$) of the soil-bentonite mixtures is given by ; $\sigma=\frac{a\cdot\varepsilon}{\varepsilon^n+b}$ 3. In shear test of the mixtures. the shear strength showed an increasing trend with increase of bentonite content and the maximum shear strength appeared at 10% bentonite content. 4. In consolidation test, the coefficient of compressibility $(a_v)$$(m_v)$$(C_v)$

• Geomechanics and Engineering
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• v.18 no.5
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• pp.503-513
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• 2019

In the present, the liquefaction potential of fiber-reinforced sandy soils was investigated through the energy-based approach by conducting a series of strain-controlled cyclic simple shear tests. In the tests, the effects of the fiber properties, such as the fiber content, fiber length, relative density and effective stress, and the test parameters on sandy soil improvement were investigated. The results indicated that the fiber inclusion yields to higher cumulative liquefaction energy values compared to the unreinforced (plain) ground by increasing the number of cycles and shear strength needed for the liquefaction of the soil. This result reveals that the fiber inclusion increases the resistance of the soil to liquefaction. However, the increase in the fiber content was determined to be more effective on the test results compared to the fiber length. Furthermore, the increase in the relative density of the soil increases the efficiency of the fibers on soil strengthening.

• Journal of the Korean Geotechnical Society
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• v.26 no.8
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• pp.5-14
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• 2010

To simulate two-dimensional plane-strain conditions in the laboratory model test, the side frictional resistance between the soil and thick glass or plastic sheet of the soil container should be reduced as much as possible. However, in fact this side friction cannot be removed completely. In this paper, the ground model simulated as a multi-sized aluminium rod mixture was introduced to get rid of the side frictional resistance and applied to the laboratory shear box test. In addition, an application of the close range photogrammetric technique to the shear box test was validated. As a result, it was found that a mean value of dilation angle from the close range photogrammetry was close to the dilation angle defined by the curve of shear strain vs. volumetric strain.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.175-183
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• 1999

Recently, problems related to vibrations of decomposed granite soils have acquired increasing attention in Korea because those soils cover approximately one third of the country. Both resonant column and cyclic triaxial test were performed to investigate deformation characteristics of unsaturated and cement-mixed decomposed granite soils in Suwon region. The important soil parameters in this respect are the shear moduli, dynamic moduli of elasticity and damping ratios. The dynamic parameters are influenced by variables such as strain amplitude, ratio of loading cycles, and degree of saturations, etc. Test results and data have shown that the optimum degree of saturation to the maximum shear modulus due to a capillary menisci effect was about 17~18 % at low strain amplitude and 10~15 % at intermediate strain amplitude. This paper suggests the range of threshold strain and mean shear modulus of decomposed granite soils in Suwon region. It also proposed the empirical relationship between the dynamic parameters for cement-mixed and non-mixed decomposed granite soils.

• Journal of the Korean Geotechnical Society
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• v.34 no.2
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• pp.5-17
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• 2018

In this study, the in-situ stress, strength and stress-strain characteristics with shear parameters (UU, CU, ${\bar{CU}}$) are analytically evaluated and the stability analyses are carried out under loading/unloading conditions. The in-situ stress and the stress-strain behaviour may become different according to input shear parameters in finite element analyses with construction step, Especially, if the internal friction angle in Mohr-Coulomb model is set to zero, the in-situ stress and the stress-strain behaviour might not be properly predicted. The results from CU parameter of total stress analysis have no significant difference with the results from CU of effective stress analysis. Therefore, in the numerical analysis for soft ground, CU parameters can be applied to predict in-situ stress and stress-strain behaviors. In addition, the calculation method was proposed to determine the shear parameter of Mohr-Coulomb model, which is corresponding to the shear strength equivalent to that of in-situ soil.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.79-91
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• 2019

Renewed interest in the long-term pile foundations has been driven by the increase in offshore wind turbine installation to generate renewable energy. A monopile subjected to repetitive loads experiences an evolution of displacements, pile rotation, and stress redistribution along the embedded portion of the pile. However, it is not fully understood how the embedded pile interacts with the surrounding soil elements based on different pile geometries. This study investigates the long-term soil response around offshore monopiles using finite element method. The semi-empirical numerical approach is adopted to account for the fundamental features of volumetric strain (terminal void ratio) and shear strain (shakedown and ratcheting), the strain accumulation rate, and stress obliquity. The model is tested with different strain boundary conditions and stress obliquity by relaxing four model parameters. The parametric study includes pile diameter, embedded length, and moment arm distance from the surface. Numerical results indicate that different pile geometries produce a distinct evolution of lateral displacement and stress. In particular, the repetitive lateral load increases the global lateral load resistance. Further analysis provides insight into the propagation of the shear localization from the pile tip to the ground surface.

• Geotechnical Engineering
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• v.11 no.1
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• pp.113-126
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• 1995

Both resonant column (RC) and torsional shear(TS) tests were performed at small to intermediate strain levels to investigate deformational characteristics of cohesive soils. The effects of variables such as strain amplitude, loading frequency, and number of loading cycles were studied. Plasticity index was found to be an important variables in evaluating these effects. Soils tested include undisturbed silts and clays and compacted subgrade soils. At small strains below the elastic threshold, shear modulus is independent of number of loading cycles and strain amplitude. Small strain material damping exists wi th ranges be tween 1.1% and 1.7% for 75 tests. The elastic threshold strain increases as confining pressure and plasticity index increases. Above the cyclic threshold strain, the modulus of cohesive soil decreases with increasing number of cycles while damping ratio is almost independent of number of load cycles. Moduli and damping ratios of cohesive soils obtanined by RC test are higher than those from 75 test because of the frequency effect. Shear modulus of cohesive soil increases linearly as a function of the logarithm of loading frequency.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.51-58
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• 2008

The objective of this study was to investigate the mechanical characteristics of fiber-reinforced lightweight soil using waste fishing net or monofilament for recycling both dredged soils and bottom ash. Reinforced lightweight soil consists of dredged soil, cement, air foam, and bottom ash. Waste fishing net or monoiament was added the mixture in order to increase the shear strength of the lightweight soil. Test specimens were fabricated with various mixing conditions, including waste fishing net content and monofilament content. Several series of unconfined compression tests and direct shear tests were carried out. From the experimental results, it was found that the unconfined compressive strength, as well as the stress-strain behavior of reinforced lightweight soil was strongly influenced by mixing conditions. In this study, the maximum increase in shear strength was obtained with either a 0.5% content of monofilament or 0.25% waste fishing net. The unconfined compressive strength of reinforced lightweight soil with monofilament was greater than that of reinforced lightweight soil with waste fishing net.