• Title, Summary, Keyword: Resistivity

Search Result 3,830, Processing Time 0.05 seconds

A Study on the Correlation of Resistivity and Rock Quality (전기비저항과 암반등급의 상관관계에 대한 고찰)

  • 권형석;신중호;황세호;백환조;김기석;김종수
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.81-88
    • /
    • 2001
  • Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity is widely used in determination of rock quality in road and railway tunnel design. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test in laboratory, such as uniaxial compressive strength(UCS), p wave velocity, Young's modulus and electrical resistivity. We correlate each test results and we found out that electrical resistivity has exponentially related to UCS and P wave velocity and linearly related to Young's modulus. And we accomplished electrical resistivity survey in field site and carried out electrical resistivity logging at in-situ area. Also we peformed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to rock classification results. We found out that electrical resistivity logging data are highly correlate to RQD, Q and RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RQD, Q and RMR.

  • PDF

A Case Study for Rock Mass Classification using Geophysical Exploration (물리탐사에 의한 터널구간의 암반등급 산정)

  • 김기석;권형석;김종훈
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.119-137
    • /
    • 2003
  • Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity Is widely used In determination of rock quality in road and railway tunnel design. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test In laboratory, such as uniaxial compressive strength(UCS), P wave velocity, Young's modulus and electrical resistivity. We correlate each test results and we found out that electrical resistivity has exponentially related to UCS and P wave velocity and linearly related to Young's modulus. And we accomplished electrical resistivity survey in field site and carried out electrical resistivity togging at In-situ area. Also we performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to rock classification results. We found out that electrical resistivity logging data are highly correlate to RQD, Q and RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RQD, Q and RMR.

  • PDF

Electrical Resistivity Characteristic of Soils (흙의 전기비저항 특성)

  • Park, Sam-Gyu;Kim, Jung-Ho;Cho, Seong-Jun;Yi, Myeong-Jong;Son, Jeong-Sul
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • /
    • pp.847-854
    • /
    • 2004
  • The resistivity of soils depends on grains size, porosity, water saturation, pore fluid resistivity, caly contents and son on. It is very important to understand the relationship between resistivity and such physical properties of soils, in order to interpret and evaluate ground conditions by using resistivity data obtained from electrical resistivity prospecting. In this paper, to study the relationship between resistivity and physical properties of soils, the resistivity of glass beads and compacted soil samples both in saturated and unsaturated conditions is measured. As the results, the resistivity of saturated soils depends mainly on porosity and clay contents, while that of unsaturated soils is sensitive to compaction conditions, and decreases with increasing water content until the optimum water condition, that is the maximum dry density. But, the relationship between resistivity and water saturation for soils is unique, being independent of compaction energy. Also, the resistivity ratio decrease with increasing water saturation, followed by no significant change of resistivity ratio over 80 percent of water saturation (the optimum water content).

  • PDF

Response of coal rock apparent resistivity to hydraulic fracturing process

  • Song, Dazhao;Wang, Enyuan;Qiu, Liming;Jia, Haishan;Chen, Peng;Wei, Menghan
    • Geomechanics and Engineering
    • /
    • v.14 no.6
    • /
    • pp.581-588
    • /
    • 2018
  • In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

A Model Study on the Variation of Apparent Resistivity along with Electric Resistivity Change of Host Rock (모암(母岩)의 전기비저항(電氣比抵抗) 변화(變化)에 따른 외견비저항(外見比抵抗)의 변화양상(變化樣相)에 관(關)한 모형연구(模型硏究))

  • Min, Kyung Duck;Jun, Myoung Soon
    • Economic and Environmental Geology
    • /
    • v.13 no.3
    • /
    • pp.159-166
    • /
    • 1980
  • A model study was conducted for the investigation of apparent resistivity variation along with electric resistivity variation of host rock and dip variation of bed. Experiments were carried out for the cases of horizontal and dipping beds in a water tank by using Wenner and Schlumberger arrays and by changing salinity of water. The ratios of resistivity values of the bed to that of brine were 1 : 10, 1 : 50, 1 : 100 and 1 : 500. Natural coally-shale of $55cm{\times}35cm{\times}3.5cm$ was used as a bed for experimental model, and brine as a host rock. Equi-resistivity curves and characteristic curves were obtained for each case of the experiment. The equi-resistivity curve was drawn both on the cross section parallel to strike of bed and longitudinal section perpendicular to it. The characteristic curve was drawn on the cross section. In the case of dipping bed of different dips, the curves are parallel to the boundary of the bed in the upper part of the bed, and are inclined to the opposite direction with the same angle of the dip of bed in the lower part. We can deduce, from the equi-resistivity curves, the location, shape and dip of the bed. It is shown in the characteristic curves that when the ratio of resistivity value of bed to that of host rock increases, the slope of curves becomes steeper, location of low-resistivity zone lower, and the width of it narrower. The slope of curves also becomes steeper when dip of bed increases. We can deduce, from the characteristic curves, the ratio of resistivity values between adjacent beds. It was found out from the experiments that electric resistivity method could be applicable to prospecting for underground geology with an electric resistivity contrast of 1 : 10. This fact strongly suggests that distinction of coal from coally-shale could be possible in a certain field condition.

  • PDF

Variation of the Electrical Resistivity with ion Components of Pore Water in the Sand (사질토 간극수의 이온 성분들에 따른 전기비저항값의 변화)

  • Yu, Chan;Yoon, Chun-Gyeong;Lee, Young-Nam;Lee, Yong-Gil
    • Journal of the Korean Geotechnical Society
    • /
    • v.15 no.1
    • /
    • pp.185-196
    • /
    • 1999
  • A laboratory experiment was performed to examine the relationship between resistivity and ionic components in the pore water of a sand by using soil resistivity test box and STING-Rl. The resistivity measurement was performed with the concentration changes of ionic components. Also, the resistivity change was evaluated for multiple components. The results showed that the resistivity of Arsenic was less than other heavy metals. In the case of complex components, resistivity ranges depended on the resistivity of components existed in the pore water.

  • PDF

Time-lapse Resistivity Investigations for Imaging Subsurface Grout during Ground Stabilization

  • Farooq, Muhammad;Park, Sam-Gyu;Kim, Jung-Ho;Song, Young-Soo
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • /
    • 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.

  • PDF

A Study on the Correlation Between Electrical Resistivity and Rock Classification (전기비저항과 암반분류의 상관관계에 대한 고찰)

  • Kwon, Hyoung-Seok;Hwang, Se-Ho;Baek, Hwan-Jo;Kim, Ki-Seog
    • Geophysics and Geophysical Exploration
    • /
    • v.11 no.4
    • /
    • pp.350-360
    • /
    • 2008
  • Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity is widely used in determination of rock quality in support pattern design of road and railway tunnel construction sites. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test in laboratory, such as P wave velocity, Young's modulus, uniaxial compressive strength (UCS) and electrical resistivity. We correlate each test results and we found out that electrical resistivity has highly related to P wave velocity, Young's modulus and UCS. Next, we accomplished electrical resistivity survey in field site and carried out electrical resistivity logging at in-situ area. We also performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to RMR data. We found out that electrical resistivity logging data are highly correlate to RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RMR.

Permeability imaging in granitic rocks based on surface resistivity profiling

  • Sudo Hiroshi;Tanaka Toshikazu;Kobayashi Tsuyoshi;Kondo Tatsutoshi;Takahashi Toru;Miyamoto Masaharu;Amagai Mitsuru
    • Geophysics and Geophysical Exploration
    • /
    • v.7 no.1
    • /
    • pp.56-61
    • /
    • 2004
  • In order to image the distribution of permeability in granitic rocks, we carried out two-dimensional (2D) resistivity profiling, together with in-situ permeability tests, electrical logging of boreholes, and resistivity measurements of rock core samples in a laboratory. Based on the electrical logging and in-situ permeability data from boreholes, we obtained empirical equations which relate resistivity and permeability of the granitic rocks in the area studied. We then applied the empirical equation to a 2D resistivity section, to produce a 2D permeability section of the granitic rocks. In this paper, we present details of the field data and of the procedure for conversion from the resistivity section to a permeability section. The observed relationship between resistivity and permeability of the rocks is also discussed.

A Study on the Resistivity Structure in Central Myanmar Basin using DC Resistivity and Magnetotellurics (전기비저항 탐사와 자기지전류 탐사 자료를 이용한 미얀마 중앙분지 전기비저항 구조 연구)

  • Noh, Myounggun;Lee, Heuisoon;Ahn, Taegyu;Jang, Seonghyung;Hwang, InGul;Lee, Donghoon;Hwang, Seho
    • Geophysics and Geophysical Exploration
    • /
    • v.22 no.2
    • /
    • pp.62-71
    • /
    • 2019
  • We conducted DC resistivity and MT survey to obtain the resistivity structure of the central Myanmar basin. We tried to analyze the underground structure through the resistivity variation of Myanmar by performing representative geophysical survey methods because researches on the electrical resistivity structure are insufficient in Myanmar. The electrical resistivity is expected to be low considering the marine sedimentary rocks composed of shale and sandstone in this area. The DC resistivity and MT survey were carried out using SmartRho of Geolux Co., Ltd. and MTU-5A of Phoenix geophysics Ltd., respectively, to visualize the electrical resistivity structure of study area. DC resistivity and MT survey showed an electrical resistivity less than dozens of ohm-m within the depth of 100 m. In particular, MT survey data were almost similar to TM and TE modes in the frequency range above 1 Hz. The two-dimensional inversion of MT data showed a subsurface structure with low resistivity below 150 ohm-m divided into east-west direction. We confirmed that the inversions of DC resisitivity and MT data along an overlapped survey line represented similar results. In the future, considering the high electrical conductivity, it would be effective to perform DC resistivity and MT survey simultaneously to study the electrical resistivity structure of the central Myanmar basin.