• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.361-368
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• 2000

In other to examine the compressibility characteristics of cohesive soils in the mouth of the Nakdong river, the oedometer tests were peformed on undisturbed and reconstituted samples obtained by continuous boring typically at 3 different sites. It is meaningful to compare the consolidation behavior of natural clays with a reference state because the natural clays are depending on the stress history, sedimentary environment and geological history. In this study, the insitu state of the Pusan clays was investigated using the concepts of ISL(Nagaraj, 2000) and ICL and SCL(Burland, 1990). And for the purpose of confirming the existence of the underconsolidated clays, a standpipe type piezometer test and a dissipation test by piezocone were performed at their sites. Consequently, the Pusan clays were evaluated as normally consolidated clays.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.134-142
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• 1997

The stability of an embankment Impounding a water reservoir is highly depend upon the location of seepage line with the embankment. To evaluate the accurate safety factor of an embankment, it is important to illustrate the seepage phenomenon. Of particular interest is the stability following a rapid change (drawdown) of reservoir level Seepage forces in embankments are easily determined if frictional forces are expressed in relation to hydraulic gradient Ⅰ. If a piezometer is inserted into a body of embankment, the level to which free water rises is a measure of the energy at that point. From model test result, it is possible to calculate safety factors of earth embankment. To assure the validity of this research, tests were conducted with numerical experimental models. And the experiment models were constructed with slopes of 1:1.0, 1:1.5, 1:2.0, 1:2.5. Analysis of experimental results, seepage force was analyzed according to downstream time, internal friction angle and cohesion, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.2
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• pp.59-66
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• 2010

This study was performed to develop the embankment protection method that can reduce demage by prevention of embankment loss and collapse from overflow due to heavy rain and flood. For overflow test, model dam was prepared and embankment behaviors were monitored with the established piezometer and strain meter during overflow. As a result of overflow test for model dam, in case of embankment without waterproof mat, the lower end of embankment was collapsed within 40 seconds after beginning of overflow. On the other hand, in case of embankment with waterproof mat, embankment collapse didn't occurred during overflow. Accordingly, establishment of waterproof mat for embankment showed that be absolutely effective for the embankment protection during overflow in reservoir. Also, it showed that the minimum establishment range of waterproof mat to prevent embankment collapse in reservoir is from maximum storage level to the lower end of embankment.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.191-201
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• 2000

In this study, the earth retaining structure using a row of piles considering plastic flow of the ground is suggested for shallow excavation works instead of conventional anchored sheet-pile wall method in the marine clays with high groundwater level. The behavior of the earth retaining structure using a row of piles is precisely observed during excavation by inclinometer and piezometer installed in opposite to the excavation side. As a result of field measurement, it was found that the behaviors of the piles and the soil were influenced mainly by slope of excavation face, interval ratio of piles, fixity condition of pile head, and stability number, etc. The earth retaining structure using a row of piles is ascertained for workability, stability, and economical construction on the soft ground having no adjacent structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.34-44
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• 2012

Many kind of sensors in the dam produce a lot of data associated with the maintenance and safety of the dam. So it is important to measure the reliability of the sensor (or measured data). In this paper, the new method using modified coherence function is proposed to measure the reliability of the sensor remotely. To verify feasibility of proposed method in the field, proposed method was applied to data of piezometer and earth pressure cell. Through field applications, the potential of the proposed method was verified.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.277-281
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• 2006

A study on stream-groundwater exchange was performed using head and temperature data of stream water, streambed, and groundwater. Groundwater level and temperature were obtained from multi-depth monitoring wells in small-scale watershed. In the summer time, time series of temperatrue data at streambed and groundwater were monitored for three months. In the winter time, we measured the temperature gradient between stream water and streambed. The observed data showed three typical types of temperature characteristics. First, the temperature of streambed was lower than that of stream water; second, the temperature of streambed and stream water was similar; and last, the temperature of streambed was higher than that of stream water. The interconnections between the stream and the streambed were not homogeneously distributed due to weakly developed sediments and heterogeneous bedrock exposed as bed of the stream. The temperature data may be used in formal solutions of the inverse problems to estimate groundwater flow and hydraulic conductivity.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1173-1177
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• 2004

현재 다양한 분야에서 널리 사용되고 있는 지하투과레이더(Ground Penetrating Radar, GPR)를 이용하여 지하수면 및 함수량을 추정하였다. 비피압대수층 내에서의 얕은 포화대(saturated zone) 깊이을 산정하는 연구(livari and Doolittle, 1994, van Overmeeren, 1994)와 포화대 상부 습윤대(wetting fronts)의 거동를 조사한 연구(Vellidis et al, 1990) 등에 활용된 바 있는 GPR 기숙을 바탕으로 비피압대수층의 통기대와 포화대 내의 함수량 및 지하수면 추정을 위한 기초 실험을 수행하였다. 지하수면 및 함수량의 현장 적용성을 검증하기 위해서는 시간과 경제적인 면에서 비효율적인 점을 고려하여 사질토로 구성된 실험용 토조를 제작하여 건조시 획득된 GPR 자료, 지하수면의 변화에 따른 GPR 이미지를 비교하여 그 적용성을 검토하고 시${\cdot}$공간적 지하수면의 정확한 추정을 위해서 삼차원으로 비교${\cdot}$검토할 수 있도록 하였으며, GPR 자료의 정확성을 검증하기 위해서 토조 하부에 액주계(piezometer)를 설치하였다. 본 연구에서 적용된 GPR 실험은 획득된 이미지의 해석에 다소 어려움이 있지만 토양을 교란시키지 않고 비교적 간편하게 함수랑 및 지하수면의 위치를 파악하는데 매우 효과적이며, 추가적으로 GPR을 이용한 다양한 실험이 수행된다면 GPR 기술은 향후 기존 방법에서 쉽게 판단하기 어려운 시${\cdot}$공간적인 함수량 및 지하수의 분포 특성을 효율적으로 파악하는데 매우 큰 도움을 줄 수 있을 것이다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.361-369
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• 2008

Control of ground water is one of the most important factors for long-term operation of tunnel because most of tunnel is located in the ground. In case of leakage tunnel, there is no pore water pressure on the lining when the drainage system is properly working. After long-term operation, however, the pore water pressure can be developed on the lining due to the deterioration of the drainage system. The increased pore water pressure on the lining is termed here as 'residual pore water pressure'. Residual pore water pressure can be measured by piezometer, but it is generally not allowed because of damages of drainage system. Therefore, an indirect and nondestructive method is required for evaluating the residual pore water pressure. Moreover, understanding of pore water pressure is needed during healthy operation of the lining. In this study, a new method for evaluation of pore water pressure on the lining during operation is proposed using theoretical and numerical analysis. It is shown that the method is particularly useful for stability investigation of pore water pressure on the lining during operation using theoretical analysis with normalized pore water pressure curve.

• 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 Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.257-267
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• 2008

Tunnels acting as drains involve groundwater-related problems such as deterioration of drainage systems or leakage through the linings. Generally initial and minor leakage problems can not be recognized by naked eyes. When the leakage over the linings is noticed, damages to structures and facilities have already occurred and could be considerable. Therefore it is vital to recognize initial leakage as early as possible and provide appropriate measures. Detection of leakage under operation requires installing piezometer. However, that may cause destruction of water proofing sheet which is generally not allowed. In this study electric resistivity method, one of the geophysical surveys, was adopted to detect possible leakage through tunnel linings. Physical lining models were made in the laboratory. The electric response was monitored for varying hydraulic conditions. It is shown that the method is very useful to detect initial leakage and monitor the malfunction of drainage system. Furthermore the method can also be used to check the quality of any repairing works of linings.