• 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 GEO-environmental Society
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• v.13 no.11
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• pp.69-79
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• 2012

This pre-supported nail method is able to decrease ground displacements more than NATM because this method reinforces ground with grouted steels before tunnel excavation. Therefore this method has advantage of being able to increase the stability and workability. This study presents applicability of pre-supported nail method with case of site measurement for shallow tunnel composed with high groundwater level and unconsolidated soil, performs this research the mechanism of new supporting system is compared with the conventional existing supporting system in terms of soil reinforcement. NATM has characteristics that construction stage displacement of the apparent height difference is observed in the step of divided excavation processing. Otherwise it is analyzed that pre-supported nail method is not sensitive in the displacement problem of excavation processing in comparison to NATM. It is found that this method is very applicable in shallow depth tunnel such as portal area, tunnel in soil and weak zone without arching effect.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.71-81
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• 2008

Wall displacements caused by earth pressure, rainfalls, rise in ground water level, inappropriate deep excavation and structural defects of the wall may produce differential settlements to existing buildings, which often result in damages and/or collapses of the building structures. In this case, measures to protect the walls and nearby structures would be required. One of the recent measures to reduce differential settlements and protecting walls is to reinforce the ground using micro-piles. In this study physical model tests were carried out to evaluate the performance of the micro-pile method. It is revealed that reduction of the settlement was maximized when the length of micro-pile is twice of the foundation width, distance between piles is twice of the pile diameter and the distance to wall is one tenth of the foundation width. Based on the test results some design recommendations were made.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.927-932
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• 2010

본 연구는 치수효과가 높은 하천제방의 안전도 향상을 위한 관리 고도화 기술 개발을 위하여 수위, 유량이 제방의 안전에 미치는 영향을 규명하고 센서 기술 적용하여 실시간 제방 안전관리 모니터링 기술을 확보하는데 있다. 이를 위해, 국내외 기술동향 및 사례분석하고, 변위발생 및 안전성 모니터링을 위한 센서 기술 적용 방안, 센서 적용시 문제점 및 개선방안, 분석방법 등에 대해 정리하였으며, 대형 토조를 이용하여 집중강우 등에 의한 수위 및 유속의 증가에 따른 하천제방에 미치는 영향을 실험적으로 규명하고, 이를 센서 기술을 적용하여 실시간 모니터링을 통한 안전성 평가 방법을 제시하고자 하였다. 하천제방은 종방향으로 긴 구조적 특성을 갖고 있으며 이러한 특성상 모든 구간에 정밀한 계측 장비를 설치하여 운영 관리함에 있어 경제적, 효율적인 측면에 있어 문제가 있는 것으로 사료된다. 따라서 주요 하천시설물 중 구조물이 하천제방을 횡단할 경우 주요 구조물에는 집중형 센서인 FBG 타입을 도입하고, 제방 연통실험 등을 통해 조사 분석된 취약 구간에 대해서는 분포형 센서인 BOTDR 타입의 광섬유 센서를 적용하여 종합적인 관리가 가능하도록 시스템 구성이 필요한 것으로 판단된다.

• The Journal of Engineering Geology
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• v.31 no.2
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• pp.135-148
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• 2021

Ground subsidence risk ratings obtained from the site investigation during pre-excavation stages could be changed depending on the parameters revealed during construction activities. A method of correcting the pre-excavation ground subsidence risk ratings based on the site conditions observed in the field is suggested in this study. The elevation of groundwater table during the excavation may be different from the predicted value depending on the application of waterproofing methods and construction conditions. The drastic drawdown of groundwater table during the excavation could cause ground subsidence due to soil volume decrease related to consolidation or compression of the ground, whereas the rising of groundwater table caused by the intense rainfall may result in a high potential for ground subsidence due to heaving or boiling of the excavation bottom. Excessive displacements of retaining walls or ground settlements may cause ground subsidence, which also results in a high risk of ground subsidence caused by the destruction of buried pipelines. Reevaluation of ground subsidence risk ratings is suggested considering the fluctuation of groundwater table, condition of groundwater leakage, measured ground displacements, and soil types. Finally, the ground subsidence risk rating system is improved for better evaluation by using 12 factors in 5 categories.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.123-131
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• 2005

In the present study, laboratory pull-out tests with screw anchors are carried out to investigate behavior characteristics of the anchors used in foundation system of underground structures which are applied to uplifting seepage forces. Small scaled pull-out tests in sand under saturated condition and dry condition were carried out. For estimating the group effects of the anchors, the upward displacement and the pullout load varied with spacing of the anchor were observed. The test results were compared with theoretical equation for the ultimate pull-out force. Also, the result of tests can be used to the finite element analysis program, $PENTAGON^{2D}$.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.9-18
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• 2011

This paper described that the failure causes of reinforced slope are analyzed based on the effect of geological and rainfall. The analysis result confirmed that the rainfall has effects on the stability of reinforced slope. Therefore, it was applied to the dewatering method using collector well for slope stabilized, and then the analysis of seepage and slope stability were conducted on slope with the applied method. The results of seepage analysis are corresponded with failure cause by rainfall and the results of slope stability, which is applied to dewatering method, are satisfied with safety factor criterion. Therefore, it confirmed that the dewatering method using collector could be possible to apply in field and reasonable method for slope stabilized during heavy rainfall.

• The Journal of Engineering Geology
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• v.23 no.1
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• pp.19-27
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• 2013

Deformation of a slope at a coal waste depot and the natural slope under the depot was surveyed and investigated at Dogye village in Samcheock city, Gangwon Province. To investigate the behaviors of the slopes, wire sensors and a rain gauge were installed on the crest of the waste depot slope and inclinometers were installed in the natural slope. The results of deformation monitoring at the crest of the waste depot slope using wire sensors revealed increased deformation with increasing cumulative rainfall. The results of monitoring horizontal deformation of the natural slope revealed that maximum horizontal deformation was also affected by cumulative precipitation. However, the groundwater level at the natural slope showed no change with rainfall. These measurements confirm that deformation at coal mine waste depots is closely related to precipitation, indicating that self-loading at such depots increases with rainfall infiltration, thus causing deformation of the waste depot slope. In addition, increasing the self-load of the coal mine waste depot may cause deformation of the underlying natural slope.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.63-70
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• 2009

The optical fiber cable acting as a sensor was embedded in the underground research tunnel and portal area in order to monitor their stability and the spatial temperature variation. This system includes two types of sensing function to monitor the distributed strain and temperature along the line, where sensor cable is installed, not a point sensing. According to the results of one year monitoring around the KURT, there is no significant displacement or movement at the tunnel wall and portal slope. However, it would be able to aware of some phenomena as an advance notice at the tunnel wall which indicates the fracturing in rockmass and shotcrete fragmentation before rock falls accidently as well as movement of earth slope. The measurement resolution for rock mass displacement is 1 mm per 1 m and it covers 30 km length with every 1m interval in minimum. In temperature, the cable measures the range of $-160{\sim}600^{\circ}C$ with $0.01^{\circ}C$ resolution according to the cable types. This means that it would be applicable to monitoring system for the safe operation of various kinds of facilities having static and/or dynamic characteristics, such as chemical plant, pipeline, rail, huge building, long and slim structures, bridge, subway and marine vessel. etc.