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

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

• Economic and Environmental Geology
• /
• v.33 no.5
• /
• pp.417-424
• /
• 2000

We applied SP monitoring and resistivity surveys using the pole-pole electrode array to seawater leakage problems in the Youngsan estuary dam and the Eoeun embankment to estimate and detect the zone of seawater leakage. The embankment is generally affected by tidal variation and has low resistivity characteristics due to the high saturation of seawater. For this reason, SP monitoring and the pole-pole array resistivity surveys, which are relatively more effective to the conductive media, were carried out to delineate the leakage zones of sea water through the embankment. We checked out electrical conductivity (EC) and temperature variations along the inner part of Youngsan estuary dam to detect the zone of seawater leakage and found that the measured EC value agreed to that of seawater in the leakage zone and the temperature was lower than that of the vicinity of leakage zone. SP monitoring results were coincided with tidal variations at each embankment. At the leakage zones in the Youngsan estuary dam and the Eoeun embankment, SP anomalies are in the range of -60~-85 mV and -20~-50 mV, respectively, and true resistivity values obtained by 2-D inversion are 3~15 ohm-m and below 0.3 ohm-m, respectively. Both SP monitoring and the pole-pole array resistivity method are found to be quite effective for investigation of seawater leakage zones in the embankment.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.5
• /
• pp.53-64
• /
• 2013

Resistivity monitoring is based on the fact that a change in the porosity leads to the changes in water content and fine particles, which alter the electrical resistivity. At every embankment dam, internal erosion always occurs as time passes. The internal erosion generally develops into piping over a long time by backward erosion and concentrated leak, and finally leads to dam failure. Resistivity is known to be very sensitive to the changes in porosity in embankment dams. Thus resistivity monitoring is a reasonable method to find out the leakage zone. However, resistivity is strongly influenced by seasonal variation of temperature, TDS of reservoir water and water level. In this paper. we first installed electrodes permanently at the center of the crest. The electrical resistivity monitoring data was acquired every 6 hours from Apr. 3, 2011 to July. 31, 2012. To analyze the characteristics of monitoring data, each resistivity data was calculated from up to 2,950 data sets. The result indicated a seasonal resistivity variation due to related temperature. Finally, a quantitative method to estimate porosities of the embankment dam from the resistivity monitoring data was analyzed. The applicability and reliability were verified and the importance of electrical resistivity monitoring for obtaining reliable result was emphasized.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2006.06a
• /
• pp.79-82
• /
• 2006

This paper presents to examine the ability of an electrical resistivity method to monitor the grouting effect at subsidence area. To monitor the changes in ground resistivity before and during the grout, series of electrical resistivity monitoring surveys have been conducted. Data has acquired in the form of grid making nine lines parallel to road and four lines traverse the road. Two kinds of electrode arrays modify pole-pole and dipole-dipole arrays were used during resistivity data acquisition. In this paper, the results show that electrical prospecting is an effective method to detect low resistivity imaging zone by grout during the ground reinforcement.

• Journal of the Korean earth science society
• /
• v.36 no.1
• /
• pp.59-67
• /
• 2015

An electrical resistivity survey is widely conducted for the safety management of embankment. In this study we investigated how a tidal variation affects the interpretation of electrical resistivity monitoring data of the embankment located in west coast. We monitored the variation of electrical resistivity on the coastal embankment where there was a high tidal variation for 3 days in every 3 hours. Electrical resistivity monitoring data showed a variation of resistivity distribution in specific area according to the time, which demonstrated some correlation with a tidal height variation. Therefore, we highly recommend that a tidal effect be considered when electrical resistivity survey is conducted on the embankment where there is a high tidal variation. For further study, we need a long term electrical resistivity monitoring and analyzing on tidal variation.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.241-244
• /
• 2007

Cement-grouts are injected into limestone cavities beneath the road in the project area, in order to improve strength and reduce permeability; the extent to which grout has penetrated in cavities need to be monitored in order to determined effectiveness of cement-grout. Geophysical approaches, offer great potential for monitoring the grout injection process in a fast and cost-effective way as well as showing whether the grout has successfully achieved the target. This paper presents the ability of surface electrical resistivity to investigate the verification of the grout placement. In order to image the cement-grout, time-lapse surface electrical resistivity surveys were conducted to compare electrical resistivity images before and after injection. Cement-grout was imaged as anomalies exhibiting low resistivity than the surrounding rocks. In accordance with field monitoring, laboratory study was also designed to monitor the resistivity changes of cement-grout specimens with time-lapse. Time-lapse laboratory measurements indicated that electrical methods are good tool to identify the grouted zone. Pre-and post grouting electrical images showed significant changes in subsurface resistivity at grouted zone. The study showed that electrical resistivity imaging technology can be a useful tool for detecting and evaluating changes in subsurface resistivity due to the injection of the grout.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.93-100
• /
• 2007

During tunnel excavation, drawdown of groundwater table or discharge from tunnel faces may not only reduce stability of tunnel and work efficiency but cause environmental problems. We have investigated the applicability of electrical resistivity survey for the establishment of the monitoring system for groundwater behavior and detecting flow channel of groundwater during tunnel excavation. The groundwater level was continuously measured at several points for 1 year. Survey was conduted at every 3 months using preinstalled electrical resistivity cables on site. The results show that observed changes in resistivity ratios in the area can be explained with observed changes in groundwater level. Thus, we believed that electrical resistivity analysed together with groundwater data can be applied for the monitoring of groundwater in tunnel area.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.10 no.4
• /
• pp.405-420
• /
• 2008

Resistivity survey is one of the widely used methods for the investigation of stability of the ground or bedrock around tunnel and is also used as an essential base data for stability and reduction of construction cost through first-hand approximation of rock quality at design step. Generally, the analysis of resistivity survey data is performed by single measurement. When distribution variation of groundwater around a tunnel over time is necessary for maintenance of a tunnel, resistivity monitoring is very useful survey method to grasp distribution variation of groundwater. So we performed the grid line resistivity survey to monitoring resistivity variation for six times. And we also tried to evaluate application possibility of the resistivity monitoring for construction safety through providing detailed information on fault zones.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.12a
• /
• pp.31-42
• /
• 2007

Dc resistivity monitoring has been increasingly used in order to understand the changes of subsurface conditions in terms of conductivity. The commonly adopted interpretation approach which separately inverts time-lapse data may generate inversion artifacts due to measurement error. Eventually the contaminated error amplifies the artifacts when reconstructing the difference images to quantitatively estimate the change of ground condition. In order to alleviate the problems, we defined the subsurface structure as four dimensional (4-D) space-time model and developed 4-D inversion algorithm which can calculate the reasonable subsurface structure continuously changing in time even when the material properties change during data measurements. In this paper, we discussed two case histories of resistivity monitoring to study the ground condition change when the properties of the subsurface material were artificially altered by injecting conductive materials into the ground: (1) dye tracer experiment to study the applicability of electrical resistivity tomography to monitoring of water movement in soil profile and (2) the evaluation of cement grouting performed to reinforce the ground. Through these two case histories, we demonstrated that the 4-D resistivity imaging technique is very powerful to precisely delineate the change of ground condition. Particularly owing to the 4-D inversion algorithm, we were able to reconstruct the history of the change of subsurface material property.