• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.386-394
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• 2019

In this study, according to drainage condition (undrained and drained) in ground, the settlement and horizontal displacement of caisson quay wall and apron in Yeongilman port due to excess pore water pressure in ground induced by the magnitude 5.4 earthquake in Pohang on November 15, 2017. In general, seismic response analysis was carried out under undrained drainage condition, but in this study, drain drainage analysis was conducted to estimate displacement during earthquake as well as an additional displacement due to dissipation of excess pore water pressure after earthquake. The result of after earthquake can not be known under undrained drainage condition. Results cleary showed that the behavior of structure and ground was dependent on drainage condition in ground. Especially, based on the drained drainage condition, the additional displacement was clearly detected due to dissipation of excess pore water pressure after earthquake. Which indicates that both results are different to drainage condition in ground, and therefore, drainage condition analysis is necessary to accurately estimate the behavior of ground and structure in seismic response analysis.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.349-360
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• 2004

This study calculated the pore water pressure, the depth of seepage, the constant of the strength in accordance with the slope inclination and the rainfall intensity over the slope built by the weathered granite soil (SP, SM). And, the change of the shear strength in accordance with the rainfall has been compared and analyzed by applying the shear strength formula of the unsaturated soil. As a result, the rainfall intensity is stronger and the slope inclination is gentler the seepage speed in accordance with the rainfall became faster proportionally. As a result of comparing and analyzing both the theoretical value of Lumb and the actual value of the model, it can be said that the actual value is faster. Since SM shows the bigger shear strength than SP, it can also be said that as the granules increase, the coefficient of permeability becomes smaller; and as the seepage rate became smaller, it affects the seepage speed. Likewise, the shear strength within the slope displays the smallest shear strength at the inclination of 1:1.5 the reason of its decrease turned out that it was due to the increase of the pore water pressure.

• Journal of the Korean Geotechnical Society
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• v.37 no.8
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• pp.5-13
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• 2021

Liquefaction behaviors of two natural silty samples containing fines including clay of 50% or more (Sample No.1 was silt 44.1% and clay 8.8%, sample No.2 was silt 57.2% and clay 12.4%) were examined by a cyclic triaxial test. According to the results on samples containing 50% or more of fine particles, an increase in the fine content decreases the liquefaction resistance of the sample. In other words, when the fine content increases, the liquefaction state of sample is reached with a small number of cyclic loads. In the relationship between the excess pore water pressure ratio and the number of cycles, the slope of the excess pore water pressure ratio increases more steeply as the fine content increases. As a result of analyzing the liquefaction behavior of the two silts with the content of clay contained in the fines, liquefaction occurred more easily in the No.2 silt with high clay content. This result shows that the clay contained in the fines affects the liquefaction behavior of the silt.

• Journal of the Korean Geotechnical Society
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• v.24 no.5
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• pp.107-115
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• 2008

This paper is performed to examine the effect of creep during the primary consolidation and the applicability of the Yin's EVP (Elasto-Visco-Plastic) model. In ordinary consolidation theories using the elastic model, the primary consolidation process can be expressed but the secondary consolidation process cannot. It is due to the viscosity, which can express the secondary consolidation, and is sometimes related to the scale effect (difference of the thickness of clay layer between laboratory sample and field condition) such as hypotheses Type A and Type B shown by Ladd et al. (1977). Usually, the existence of the creep during the primary consolidation has been conformed and the Type B is well acceped. On the other hand, from the large-scaled consolidation tests the intermediate characteristic between Type A and Type B was proposed as Type C by Aboshi (1973). In this study, to clarify the effect of creep on the settlement-time relation during the primary consolidation in detail, Type B consolidation tests were performed using the separate-type consolidation test apparatus for a peat and clay. Then the test results were analyzed by using Yin's EVP Model (Yin and Graham, 1994). In conclusion, followings were obtained. At the end of primary consolidation, the compression for the subspecimens should not be the same because of the difference of the excess pore water pressure dissipation rate. And the average settlement measured by the separate-type consolidometer coincides with the analyzed one using the Yin's EVP model. As for the dissipation of the excess pore water pressure, however, the measured excess pore water pressure dissipates faster compared with the Yin's model.

• Journal of the Korean GEO-environmental Society
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• v.24 no.8
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• pp.5-11
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• 2023

Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

• Geotechnical Engineering
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• v.9 no.1
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• pp.45-58
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• 1993

Paper drain method is one of the methods used for the improvement of soft clay as hydraulic fill sites or the seaside industrial complex. This method adopts a card board as the drain materials instead of sand piles in sand drain method. In this paper 3 types of drain board are used to fond out the characteristics of consolidation by vacuum consolidation model test. So does the no drain board test. This test causes the reduction of pore water pressure to promote the settlement without change of ground water level. Conclusively, the vacuum consolidation shows 3-dimensional behaviors and pore water pressure reaches a negative value in a short time. In addition, it is expected to have a comparatively good consolidation effect using non -woven board, and vacuum loading results in increasing the shear strength at the bottom and top of call layers.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.493-504
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• 2011

This study was carried out to safety evaluation, the practical application and improvement of design method of the agricultural reservoir due to raising embankments. Also, it was to compare and analyze the pore water pressure (PWP), seepage (leakage) quantity and piping phenomenon according to high water table and rapid drawdown. The seepage analysis by finite element analysis was used for steady state and transient condition. The pore water pressure distribution for steady state and transient condition showed positive(+) PWP on the upstream slope, it was gradually changed negative(-) PWP on the downstream slope. The PWP in the core ranged from 100 ~ -33 kPa, the seepage line in the incline-type core suddenly decreased towards the lower levels from the higher levels. The PWP according to rapid drawdown is remained in the vicinity of the upstream slope, therefore, it is investigated to be in an unstable state by the slope stability analysis. The PWP after raising embankments showed smaller than in the before raising embankments. It was likely to be the piping phenomenon because the gradients in the before raising embankments showed largely at downstream slope, and the stability for piping in the after raising embankments increased stable state. The seepage quantity per 1 day and the leakage per 100m for the steady state and transient condition appeared to be safe against the piping. It reduced slightly regardless of the transient condition before the raising embankments and it decreased largely about 2.4 times in the early days after the raising embankments.

• Journal of the Korean Geotechnical Society
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• v.33 no.4
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• pp.5-15
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• 2017

Three-hinge failure occurs in a jointed rock slope with a joint set parallel with slope and a conjugate joint set. Limit Equilibrium Method (LEM) and Finite Element Method (FEM) which are commonly used for slope design, are not suitable for evaluating stability against three-hinge failure, and this study performed parametric study to analyze the failure mechanism and to find influence factors causing three-hinge failure using UDEC which is a commercial two-dimensional DEM based numerical program. Numerical analyses were performed for various joint structural conditions and joint properties as well as ground water conditions. It was found that pore water pressure is the main factor triggering the three-hinge failure and the mode of failure depends on friction angle of basal joint and bedding joint set. The results obtained from this study can be used for adequate and economic footwall slope reinforcement design and construction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.136-145
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• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.1
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• pp.17-24
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• 2007

An experimental investigation was carried out for 4 different types of the aluminum foam heat sinks which were inserted into the annulus. The purpose of this study is to examine the feasibility of a heat sink with high performance forced convective water cooling in the annulus. The local wall temperature distribution, inlet and outlet pressures and temperatures, and heat transfer coefficients were measured for heat flux of 13.6, 18.9, 25.1, 31.4 $kW/m^2$ and Reynolds number ranged from 120 to 9,000. Experimental results show that the departure from the Darcy's law is evident from the pressure loss and the friction factor is much higher while the significant enhancement in Nusselt number is obtained, and average Nusselt number of aluminum foam with high pore density is much higher than that of aluminum foam with low pore density. Correlations for the friction factor is proposed and used for design of thermal applications.