• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.487-494
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• 2005

In order to estimated a reason of soil slope failure new measurement technology is demanded to measure a variation of volumetric water content which is a key physical parameter for understanding the slope failure in the field. In this study a laboratory soil tank test were conducted to use RDB and ADR measurement probes for measuring the variation of volumetric water content. These experiments were compared with two physical parameters as volumetric water content and pressure water head which are estimated to the compacted weathered granite soil under the artificial rainfall, 7.5mm/hour, in the whole of two stages. From the results the variation of volumetric water content and pressure water head is represented to nearly similar travel time.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.5-10
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• 2004

The earth pressure coefficient at rest for clayey soils in the one-dimensional state, $K_0$ obtained from the triaxial test is not correct in principle because the seepage flow is radial and the displacement of soil elements is three-dimensional. Measurements of the earth pressure and the pore water pressure during one-dimension consolidation in the consolidometer ring are presented. The earth pressure and pore water pressure are measured directly by a circular part of the consolidometer ring of a floating type at its mid height. A plastic clay showed $K_0$=0.5 irrespective of pressure in the consolidometer ring.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.71-76
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• 2005

The subject of this paper is research into the application of resistivity/SP monitoring to detecting the water leakage of water utilization facilities. For this purpose, we installed a comprehensive monitoring system consisting of resistivity/SP measurement, inclinometer, piezometer, and water gauge at an embankment, Using this monitoring system, we monitored the various kinds of measurement data and compared the resistivity structures and SP variations that of hydrological and engineering data in order to investigate the water leakage and stability of the embankment. The variations of resistivity and SP at the embankment were provided from the monitoring data and we could accurately locate the portions of which resistivities and SP have sharply changed, Furthermore, we could estimate the stability of the embankment more effectively and quantitatively by jointly interpreting the monitoring data of resistivity and SP, water level, pore water pressure, and subsurface displacement. The monitoring experiments in this study led us to the conclusion that for the efficient maintenance of the water utilization facilities, monitoring the resistivity and SP data would be much more preferable to performing the just one-time measurements.

• Journal of the Korean Geosynthetics Society
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• v.21 no.1
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• pp.23-32
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• 2022

This study is conducted to minimize the problems caused by the difference between the settlement and settlement time of the one-dimensional consolidation analysis by the Terzaghi's consolidation theory, which is generally used in domestic soft soil design, from the settlement and settlement time measured at the field site. Consolidation-time factor considering the field site characteristics can be determined using the relationship among the degree of consolidation, settlement time, and time factor, the time-settlement curve measured at the field is reverse- analysis using a numerical-analysis technique to reproduce the same consolidation behavior as in the field. Time-settlement and time-excessive pore water pressure data when the same consolidation behavior as the site is reproduced Consolidation-time factor of the soil of Songsan Green City by settlement and excess pore water pressure was calculated using the settlement and excess pore water pressure for each settlement time. If the results of this study use the Terzaghi consolidation-time factor, which does not consider the consolidation characteristics of the soft ground target area, it is difficult to determine the end time of the soft ground during construction. It is necessary to use the established settlement-time factor.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1181-1187
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• 2009

과잉간극수압의 소산 속도는 일반적으로 압밀방정식에서 정의하는 압밀계수에 의해 결정 되는데, 이 압밀계수는 투수계수와 체적압축계수의 관계로 얻어지는 흙이 특성이며 동일한 성질의 지반에서라도 측정위치에 따라 그 값의 편차가 심한 특성을 보인다. 이에 본 연구에서는 위치적 이질성이 있는 점성토 지반의 압밀과정이 균질한 지반에서의 압밀과 어떤 차이를 보이고, 위치적 이질성으로 인한 불확실성이 압밀소요시간이나 압밀속도에 미치는 영향에 대해 유한차분법을 이용한 수치적인 방법으로 고찰하였다.

• Journal of the Korean Geotechnical Society
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• v.30 no.5
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• pp.55-65
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• 2014

Most shield tunnels are designed based on the assumption of a undrained condition. But they are operated as drained tunnels in which underground water flows and passes through a drainage facility. Therefore, it is necessary that the drainage condition be considered in the shield tunnel design. In this research, new testing device which can simulate the underground tunnel located below ground water level, was developed. Total stress and pore water pressure were examined and an inflow water into an inner pipe was measured using the testing device. Test results showed that the total stress, which was the sum of effective stress and pore pressure, increased more in an undrained condition and an inflow water into an inner pipe was proportional to the water pressure but inversely proportional to the loading stress. Consequently, if the drainage is considered in the shield tunnel design, the more economical design can be expected because of the stress reduction of the lining.

• Journal of the Korean Geosynthetics Society
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• v.21 no.1
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• pp.1-10
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• 2022

In this study, a model parameter evaluation method using relative density was proposed to utilize applicable UBC3D-PLM for liquefaction behavior. In addition, dynamic effective stress analysis, that is, liquefaction analysis, was performed on the case of the liquefaction occurrence region where acceleration and pore water pressure were measured, and compared with the actual measurement and the existing Finn analysis results. Through this study, it was found that the proposed method can easily evaluate the necessary parameters required by the related model and predict the pore water pressure behavior in the region where liquefaction occurs. In addition, in the case of the study area, both measurements and numerical analysis showed that liquefaction occurred when a certain amount of time elapsed after the earthquake acceleration reached the maximum value. In the case of UBC3D-PLM applied in this study, the excess pore water pressure behavior similar to the actual measurement was predicted, and the occurrence of liquefaction was evaluated in the same way as the actual measurement. In particular, although the excess pore water pressure in the sand layer was greater, the phenomenon in which liquefaction occurred in the silt layer was accurately realized. It is expected that the proposed model parameter evaluation method and finite element analysis applying UBC3D-PLM can be used to select the liquefaction reinforcement region in the future seismic design and reinforcement by evaluating the liquefaction occurrence region similarly to the real one.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.1-12
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• 2016

In this study, the impact of sand and weathered granite soil is analyzed by changing the internal temperature from $20^{\circ}C{\sim}70^{\circ}C$C by installing a heating coil inside the triaxial cell. To check the effect on weathered granite soil due to increase of temperature and number of heating-coiling cycles are analyzed by measuring the temperature by using thermometer installed inside the triaxial cell and due to that deviator stress also occurred during the consolidated undrained test. To analyze the effect of weathered granite soil with change of temperature during undrained testing. The deviator stress and pore pressure is measured. As a result, pore pressure increases and the deviator stress decreases with rise of temperature.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.177-183
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• 2005

The subject of this paper is research into the application of electrical resistivity monitoring to detecting the water leakage of water utilization facilities. For this purpose, we installed a comprehensive monitoring system consisting of resistivity measurement, inclinometer, piezometer, and water gauge at an embankment. Using this monitoring system, we monitored the various kinds of measurement data and compared the resistivity structures and that of hydrological and engineering data in order to investigate the water leakage and stability of the embankment. The variant images of electrical resistivity at the embankment were provided from the monitoring data and we could accurately locate the portion of which resistivities have sharply changed. Furthermore, we could estimate the stability of the embankment more effectively and quantitatively by jointly interpreting the monitoring data of resistivity, water level, pore water pressure, and subsurface displacement. The monitoring experiments in this study led us to the conclusion that for the efficient maintenance of the water utilization facilities, monitoring the resistivity data and hydrological data would be much more preferable to performing the just one-time measurements.

• Journal of the Korean Geotechnical Society
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• v.22 no.9
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• pp.61-68
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• 2006

Recently the large scale civil engineering projects are being implemented by reclaiming the sea or utilizing seashore and river embankment areas. The reclaimed land and utilized seashore are mostly soft ground that doesn't have sufficient bearing capacity. This soft ground consists of fine-grained soil such as clayey and silty soils or large void soil like peat or loose sand. It has high ground water table and it may cause the failure and crock of building foundation by uplift pressure and ground water leakage. In this study, the permittivity and the transmissivity were evaluated with the applied normal pressure in the laboratory. The laboratory model tests were conducted by utilizing geocomposite drainage system for draining the water out to release the uplift pressure. The soil used in the laboratory drainage test was dredged soil from the reclaimed land where uplift pressure problems can arise in soil condition. Geocomposite drainage system was installed at the bottom of apparatus and dredged soil was layered with compaction. Subsequently the water pressure was supplied from the top of specimen and the quantities of drainage and the pore water pressure were measured at each step water pressure. The results of laboratory measurements were compared with theoretical values. For the evaluation of propriety of laboratory drainage test, 2-D finite elements analysis that can analyze the distribution and the transferring of pore water pressure was conducted and compared with laboratory test results.