• Geophysics and Geophysical Exploration
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• v.22 no.3
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• pp.160-167
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• 2019

Resistivity inversion result may be distorted if the seepage line fluctuation within central core with the change of reservoir water level as well as the conductivity of the reservoir water is not taken into consideration because the reservoir dike is composed of three-dimensional (3D) resistivity structure. Consequently, to accurately analyze the resistivity changes inside the reservoir dike according to the change of reservoir water level, 3D electrical resistivity modeling for the 2D survey line considering topography and physical properties of dam components was carried out. In addition, 2D inversion was performed with the simulated 2D resistivity data for a given 3D model in order to compare it with the inversion result of real field data. For 283 reservoirs in Korea, 2D inversion results for the simulated 2D data and field 2D resistivity data were compared. Finally, the reservoirs with an inversion ratio of 50% or less were selected as reservoirs that require further precise investigation.

• 한국지구물리탐사학회:학술대회논문집
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• 2001.09a
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• pp.122-140
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• 2001

We have applied the geophysical survey, mainly electric and electromagnetic (EM) methods, to a test site contaminated by hydrocarbon waste disposal and local spill. The multi-frequency, moving source & receiver EM survey along with ground penetrating radar (GPR) showed a fairly good performance in detection of buried metal pipes and objects. Magnetic survey measuring vertical and horizontal gradients were so sensitive to the small metallic objects spread over the surface that it's hard to discriminate the buried pipe. We chose electrical resistivity, EM and GPR survey to examine the soil contamination. Depth slices of resistivity distribution as the results of the inversion of resistivity and EM data coincided each other and closely matched the contaminated area determined by chemical analysis of the soil samples. GPR images did not show the reflection events related with contamination plume since there are no distinct spill in this site. We inferred the contamination using the penetration depth of the GPR energy, which could be used as auxiliary information to the resistivity and EM results. We summarized the applicability of each survey methods based on this results and proposed a desirable survey scheme for the determination of hydrocarbon contaminated site.

• Journal of the Korean Society of Groundwater Environment
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• v.3 no.2
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• pp.95-100
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• 1996

Schlumberger electrical soundings and Coincident loop time-domain electromagnetic soundings were made on the Nanji-do landfill to investigate the nature of fills and the subsurface structure. The measured data were transformed into apparent resistivity values and then inverted in terms of 1-D resistivity models. At 6 points, both measurements were carried out to check the validity of the interpreted subsurface electrical structures. Interpreted layered models from each method show a good agreement. Obtained models show that a conductive zone exist below the shallow resistive zone. Conductive zone, which is considered to be influenced by decomposition of organic waste materials and infiltration of precipitation, is terminated by resistive zone which is considered as basement. Considering the fact that conductive zone extends to the basement and there exist no barrier layers such as clay layers, contaminant plumes are likely to flow into the groundwater directly.

• Economic and Environmental Geology
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• v.39 no.5 s.180
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• pp.597-605
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• 2006

In this study, we examined the applicability of 3-D electrical resistivity survey to detect underground cavities within ground subsidence area at the field test site, located at Yongweol-ri, Muan-gun in Korea. Underground cavities are widely present within the limesilicate bedrock overlain by the alluvial deposits in the area of the test site where the ground subsidences have occurred in the past. The limesilicate cavities are mostly filled with groundwater and clays in the test site. Thus, cavities have low electrical resistivity compared to the surrounding host bedrock. The results of the study have shown that the zones of low resistivity correspond to the zones of the cavities identified in the boreholes at the test site, and that the 3-D electrical resistivity survey is very effective to detect underground cavities.

• The Journal of Engineering Geology
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• v.22 no.4
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• pp.409-416
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• 2012

In this study, an electrical resistivity survey and a drilling investigation were conducted at an animal carcass disposal site. Chemical analysis of leachate collected from the site was also performed (sampling times: May 2011 and June 2012). Five lines of dipole-dipole electrical resistivity surveys were carried out, along with drilling investigations at 3 points within the disposal areas and 11 points near the disposal site. Two-dimensional inverse modeling of the collected resistivity data was performed to evaluate the properties (size, depth, and form) of the disposal site. Leachate analysis showed that pH of leachate decreased from 7.4 to 6.7, while Eh changed from -358 mV to -48 mV over time. In addition, dissolved ions increased due to the progression of carcass decomposition. Results of the electrical resistivity survey indicated that low resistivity zones (minimum value, $0.64{\Omega}m$) existed at a depth of 8 m from the surface. Considering the bedrock location and carcass disposal depth, there was no evidence of bedrock contamination by leachate. The results of the electrical resistivity survey are consistent with those of the drilling investigation, which indicates that electrical resistivity effectively depicted the properties of the disposal site. This study demonstrates that electrical resistivity survey is a suitable technique for investigation of animal carcass disposal sites.

• Journal of the Korean Geophysical Society
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• v.5 no.4
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• pp.329-336
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• 2002

Electrical resistivity dipole-dipole, seismic refraction, and seismic reflection methods were performed to delineate the boundaries the Yongdong basin(Cretaceous) in terms of physical properties and to ultimately identify the margin architectures of the faults or unconformities. Higer resistivities (approximately >2000 ohm-m) most likely originate from the basement of the basin, contrasting with the lower resistivities from infilled sedimentary rocks. Faults at the eastern margin and unconformities at the western boundary are characterized as high-slope($70^{\circ}$) and gentle-slope($30^{\circ}$) gradients in the resistivity sections, respectively Such features for the boundaries are also suggested by the lower values of seismic velocity and resistivity for the western margin.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.21-36
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• 1999

Recently resistivity survey is widely used for site investigations in the field of civil engineering. Since such application area requires accurate interpretation tools especially in the area of complicated geology and rough terrain topography, we developed a three-dimensional (3-D) resistivity inversion code, which can reconstruct real earth structures. Furthermore, the inversion code gives resolution-enhanced images by applying the ACB(Active Constraint Balancing) method. With the help of this inversion code, 3-D resistivity survey is now used as new techniques for site investigations in civil engineering problem. By imaging the 3-D resistivity distribution, we could get useful informations such as depth distribution of basement rock, distribution of weak zone, fractures and cavities which is crucial to civil engineers.

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.126-132
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• 2002

• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.126-138
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• 2002

Designing the bridge with wider span is the present-day trends. Therefore, constructing the foundation on the suitable ground is one of the important factor for the safety of bridge. But, getting a subsurface information under the river is not easy problem. This paper shows results of electrical resistivity survey at the river. Electrical resistivity survey have revealed geoelectrical structure successfully. The result is well matched with boring and can provide useful information on the geological structure such as fault fracture zone for suitable location of foundation. It is expected that application of electrical resistivity survey at the river will be helpful in preventing modification of design due to unexpected ground condition during the construction, or water contamination and increment of costs accompanied with ground reinforcement.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.111-122
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• 1999

한반도 남동부 경상분지에 위치한 양산단층의 지전기학적 구조를 밝히기 위하여 경주시 이조리와 울산시 서하리, 양산시 삼감리와 회산리 사이에서 전기비저항 탐사를 수행하였다. 단층파쇄대는 낮은 전기비저항값을 가지며 단층파쇄대에 분포하는 풍화대는 남쪽으로 향할수록 두꺼워지는 것으로 나타났다. 풍화대의 깊이는 서하리와 회산리에서 약 100 m 이며 다른 지역에서는 약 50-70 m 정도이다. 단층파쇄대에 위치하는 풍화대의 전기비저항값은 회산리에서 얻어진 약 10 Ωm의 매우 낮은 값을 제외하고는 약 40-300 Ωm 정도이다. 연구지역 내에서는 풍화대 하부에 위치하는 기반암의 깊이가 양산단층을 따라 남쪽으로 향할수록 깊어지는 특징적인 변화 양상을 갖는 것으로 보인다. 수평탐사 결과는 양산단층에 가까워질수록 겉보기 비저항값이 감소함을 보여준다