• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.121-133
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• 2013

This paper presents the results of an investigation into the pull-out capacity characteristics of screw anchor piles. Theoretical background of screw anchor pile (SAP) was first discussed. A series of reduced-scale model tests were performed on a number of cases with different SAP geometries such as pitch and diameter of screw as well as relative density of the model ground. The applicability of the pull-out capacity prediction equations were also examined based on the test results. It was shown that the pitch of screw has negligible effect on the pull-out capacity, while the diameter of screw has relatively large effect on pull-out capacity under a given condition. Practical implications of the findings from this study are discussed in great detail.

• Journal of the Korean Geotechnical Society
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• v.31 no.2
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• pp.13-25
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• 2015

With the increasing usages of micropile, several researchers have been studying the bearing characteristics of micropile or micropile-raft system. But most cases of research were focused on the bearing capacity of micropile-raft system on sand layer. And it was not considered that the bearing capacity of micropile-raft system was affected by the failure mode of soil and pile installation conditions. Thereby this study conducted the numerical analysis to estimate the bearing capacity of micropile-raft system on sand or silt layer with different shear failure mode. It was found that the bearing capacity of micropile-raft system installed in positive or negative angle was larger than that of the system installed in vertical angle, in the case of the sand layer undergoing the general shear failure. In the case of silt layer undergoing the punching shear failure, the bearing capacity of micropile-raft system installed only in negative angle was larger than that installed in vertical or positive angle. And the bearing capacity of foundation system in positive angle was similar to the vertical micropile-raft system.

• Journal of the Korean Geotechnical Society
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• v.27 no.11
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• pp.27-37
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• 2011

A series of centrifuge model tests to investigate the suction pile pullout loading capacity in sand have been performed. The main parameters that affect the pullout loading capacity of a suction pile include the mooring line inclination angle and the padeye position of the suction pile. With respect to the padeye position, the maximum pullout loading capacity is obtained when the padeye position is near 75% of the pile length from the top. The direction of the pile rotation changes when the padeye position reaches somewhere near 50~75% for all mooring line inclination angles. The translation displacement of suction pile to develop the time of maximum pullout loading capacity decreased as the mooring line inclination angle increased. In addition, the vertical displacements of the center of a suction piles for all cases appeared to develop toward the ground surface.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.740-745
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• 2000

Effects of porous fences on the wind erosion of sand particles from a triangular pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Particle motion was visualized to see the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the fence porosity ${\varepsilon}$. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity ${\varepsilon}=30%$ was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.55-65
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• 2012

This study performs model test to propose the installation method of micro-pile appropriate to various soil conditions such as sand or silt soil. As a result, the crossed installation method (${\theta}$ < $0^{\circ}$) of micro-pile is effective in resisting a compression displacement of soil in the case of silt exhibiting the punching shear failure. And the inclined installation method (${\theta}$ > $0^{\circ}$ or ${\theta}$ < $0^{\circ}$) of micro-pile is effective in resisting a lateral displacement of soil in the case of sand to exhibiting the general or local shear failure.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.253-261
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• 2003

Mechanical behavior of composition pound improved by sand compaction pile (SCP) with low replacement area ratio could be more significantly affected by mechanical interaction between sand piles and clays than that of clay ground improved by SD or SCP with high replacement area ratio. It is essential to elucidate the mechanical interaction in the improved clay ground, in order to accurately estimate behavior in reducing settlement of the improved ground and increasing strength of clays. In this paper, through a series of model tests of composition ground improved by SCP with low replacement area ratio, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing behavior between sand piles and clays.

• Journal of the Korean Geotechnical Society
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• v.36 no.2
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• pp.29-42
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• 2020

In this study, centrifuge tests were performed to investigate the effect of the lateral load-moment combination on the p-y curves for 7 m-diameter monopiles installed in sand for offshore wind turbine. For the objectives, a centrifuge testing system was developed and tests were conducted at an acceleration of 68.83 g using well-instrumented model monopiles under two different lateral load-moment combinations simulated by different loading heights: 1 and 5 times monopile diameter from the ground surface. The sand was prepared as medium loose sand. Based on the centrifuge test results, the experimental p-y curves were evaluated and compared with previous literatures including API codes. The experimental results reveal that the p-y curves were little influenced by the combination of lateral load and moment. It was also found that the embedded length affects p-y curves.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1175-1184
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• 2000

Effects of porous wind fences on the wind erosion of particles from a triangular sand pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Flow visualization was carried out to investigate the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the particle size, fence porosity $\varepsilon$ and the height of sand pile. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity $\varepsilon$=30% was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles. With increasing the sand particle diamter, the threshold velocity was also increased. When the height of sand pile is lower than the fence height, threshold velocity is enhanced.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.45-50
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• 2005

Sand pile method, such as sand drain method and sand compaction pile method, has been popularly used as an improved method for soft clay grounds. The effect of accelerating consolidation of soft clay grounds has been evaluated with Barren's solution. The consolidation behavior of soft clay ground with sand piles strongly depends on both the nonlinear mechanical interaction between sand piles and surrounding clays and the degradation permeability of clays. In this paper a method of determining consolidation parameters of soft clay ground with sand drains by using Barren's solution was proposed through a series of numerical simulations. Through the method, the change in both volume compressibility and permeability during consolidation was reasonably evaluated.

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.37-49
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• 2021

Micropiles are widely used in construction field to enhance bearing capacity and reduce settlement of existing foundation. It has various benefits such as low construction expense, simple installation process, and small construction equipment. Recently, new microple equipped with the base expansion structure at the end has been developed to improve the foundation bearing capacity. The improvement of load capacity can be conceptually achieved by expanding the base expansion structure when a load is applied to the micropile. However, the expansion mechanism of the base expansion structure and the improvement of load capacity of the micropile were not yet experimentally validated. Therefore, in this study, a series of centrifuge model tests was performed to evaluate the effect of the base expansion structure on the improvement of load capacity. Two types of soil, sand and weathered rock, were prepared and the loading tests were performed using the real micropile with the base expansion structure. During the tests, the earth pressures surrounding the base expansion structure were monitored. As a result, when a load of 30 kN was applied to the micropile, the increase in the ratio of the horizontal to vertical pressure increment (∆σ_h/∆σ_𝜈) ranged from 0.4 to 0.58 in sand and ∆σ_h/∆σ_𝜈 = 0.19 in weathered rock, respectively. Therefore, it can be concluded that the increase in the horizontal earth pressure adjacent to the base expansion structure will improve the bearing capacity of the micropile.