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Hassan, Asem Ahmed. "Electrical resistivity method for water content characterisation of unsaturated clay soil." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10806/.
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This thesis presents an automated multi-electrode resistivity system which was developed for the water content characterisation of unsaturated clay soil. The system controls 64 electrodes in a fully automated procedure, offering continuous real-time data acquisition, which is one of the recent advances in resistivity instrumentation. The system was tested using a wide range of high precision reference resistors and different soils, and validated using commercial standard instruments. The results indicated a high precision, accuracy and resolution of the outputs, with a measurement error of 0.19% (maximum 0.80%) in a four-electrode method and 0.21% in an automated acquisition mode. Water content characteristics of mechanically compacted BIONICS clay soil was extensively investigated, with particular focus on the effect of wetting, drying and cracking on soil properties. It was found that the electrical resistivity of soil is sensitive to water content and compaction conditions. Experimental relationships that relate soil resistivity, volumetric water content and degree of saturation were developed. These relationships are useful to estimate the in situ water content. The resistivity behaviour of clay soils subjected to drying and wetting procedures was discussed. Soil water content and microstructure changes are key controlling parameters for resistivity behaviour. Numerical and experimental techniques were used to characterise cracking in clay soils. The results showed that cracks have anomalous high resistivity values that can be distinguished from the background, and changing cracking depth, length, width and orientation causes significant changes in soil resistivity. As the cracks form barriers that disturb the flow of electrical current, the depth and length of the crack have the major influence on soil resistivity. It was concluded that the degree of saturation or volumetric water content is a more reliable parameter than the gravimetric water content to calibrate in situ resistivity data against water content and soil resistivity can be used as a useful indicator for monitoring water content changes in clay soils subjected to drying and wetting cycles.
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Liu, Shuyun. "A sequential inverse approach for hydraulic tomography and electrical resistivity tomography: An effective method for site characterization." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279846.
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Hydraulic tomography (i.e., a sequential aquifer test) has recently been proposed as a method for characterizing aquifer heterogeneity. In this study a sequential inverse approach is developed to interpret results of hydraulic tomography. The approach uses an iterative geostatistical inverse method to yield the effective hydraulic conductivity of an aquifer, conditioned on each set of head/discharge data. To efficiently include all the head/discharge data sets, a sequential conditioning method is employed. Two-dimensional numerical experiments were conducted to investigate the optimal sampling scheme for the hydraulic tomography. The effects of measurement errors and uncertainties in statistical parameters required by the inverse model were also investigated. The robustness of this inverse approach was demonstrated through its application to a hypothetical, three-dimensional, heterogeneous aquifer. Two sandbox experiments were conducted to evaluate the performance of the sequential geostatistical inverse approach under realistic conditions. One sandbox was packed with layered sands to represent a stratified aquifer while the other with discontinuous sand bodies of different shapes and sizes to represent a more complex and realistic heterogeneous aquifer. The tomography was found ineffective if abundant head measurements were collected at closely spaced intervals in a highly stratified aquifer. While it was found beneficial when head measurements were limited and the geological structure was discontinuous. The sequential inverse approach for hydraulic tomography was extended for electrical resistivity tomography. Numerical experiments were conducted to demonstrate the robustness of this approach for delineating the resistivity distribution in the subsurface and to investigate effectiveness of different sampling arrays of the ERT: the surface, the down-hole, and the combination of the surface and down-hole array. Orientation of bedding was found to dictate the effectiveness of the ERT layout. Samples were collected to quantify spatial variability of the resistivity-moisture relationship in the field. Numerical experiments then illustrated how the spatially varying relationship exacerbated the level of uncertainty in the interpretation of change of moisture content based on the estimated change in resistivity. A sequential inverse approach was then developed to estimate water content with less uncertainty by considering the spatial variability of the resistivity-moisture relationship and incorporating point moisture measurements and ERT data sets.
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Gagliano, Michael Paul. "Assessment Of Electrical Resistivity Method To Map Groundwater Seepage Zones In Heterogeneous Sediments At Mirror Lake, NH." Master's thesis, Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/83757.
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GeologyM.S.
Temporal and spatial variability makes locating zones of seepage difficult using traditional point measurements. The goal of this project was to employ 2D electrical resistivity, 3D electrical resistivity, and time-lapse resistivity to improve our understanding of how small-scale heterogeneity controls seepage. We collected underwater electrical resistivity data along the southwest shore of Mirror Lake, NH, as part of a multi-year assessment of the utility of geophysics for mapping groundwater seepage beneath lakes. We found that resistivity could predict out-seepage. A line collected perpendicular-to-shore along the lake bottom starting 27-m off shore and continuing 27-m on shore (1-m electrode spacing) showed the water table dipping away from the lake, the steep gradient indicative of high out-seepage in this area. Resistivity could also broadly delineate high-seepage zones. An 80-m line collected parallel to shore using 0.5-m electrode spacing was compared with measurements collected the previous year using 1-m electrode spacing. Both data sets show the transition from high-seepage glacial outwash to low-seepage glacial till, demonstrating reproducibility. However, even the finer 0.5-m electrode spacing was insufficient to resolve the heterogeneity well enough to predict seepage variability within each zone. In two sections along this 80-m line, one over glacial outwash, the other over till, we collected 14 parallel lines of resistivity, 13.5-m long and spaced 1-m apart to form a 13.5 x 13-m data grid. These lines were inverted using two methods: 1) individually using a 2-D inversion program and then interpolated to create a 3-D volume and 2) they were jointly inverted to create a 3-D volume. Examination of resistivity slices through these volumes highlights the heterogeneity of both these materials, suggesting groundwater flow takes indirect flow paths. However, only when there was a strong contrast in resistivities (the till section) could a possible groundwater flow path be identified. Time-lapse resistivity was used to determine the effect of the top layer of fine sediments. A 13.5-m long time-lapse resistivity survey was completed in the glacial till using 0.5-m electrode spacing showed that disturbing only a few millimeters of superficial sediments produced up to a 6% change in resistivity. This change was accompanied by changes in seepage, indicating that the fine layer of sediments is a major control on seepage patterns. This project showed that combining several electrical resistivity methods provides a better understanding of subsurface heterogeneity and aids in the placement of point measurements. However, in such heterogeneous material the goal of predicting seepage variation still remains difficult.
Temple University--Theses
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Gandolfo, Otavio Coaracy Brasil. "Um estudo do imageamento geoelétrico na investigação rasa." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/44/44133/tde-25042008-142218/.
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Este trabalho trata do estudo detalhado e com profundidade das metodologias de aquisição, processamento e interpretação de dados de caminhamentos elétricos, sob o enfoque de investigações voltadas a objetivos rasos. Nas técnicas de aquisição 2D (caminhamentos) foram utilizados os arranjos dipolo-dipolo, pólo-dipolo, pólo-pólo e Wenner, permitindo comparações quanto à eficácia dos mesmos. Foi testada uma genuína aquisição 3D utilizando o arranjo pólo-pólo, avaliando-se suas potencialidades e limitações. O Schlumberger foi o arranjo empregado para a execução de SEVs que auxiliaram na interpretação e quantificação das seções geoelétricas 2D, principalmente no que se refere à distribuição vertical das resistividades. Os modelos geoelétricos 2D foram obtidos com um programa de inversão de dados (RES2DINV) que, em tese, é capaz de corrigir as distorções observadas nas pseudo-seções de resistividade elétrica aparente correspondentes aos diversos arranjos utilizados no trabalho. Estes modelos constituem imagens que apresentam uma melhor correspondência com a realidade geológica em subsuperfície, o que facilita a interpretação dos resultados. Procurou-se explorar o máximo as potencialidades do programa de inversão, visando a obtenção de imagens de boa qualidade. A interpretação geofísica foi sempre efetuada com base em informações diretas disponíveis (furos de sondagem, trincheiras, poços e afloramento). Em uma escala de investigação rasa, a resolução passa a ter uma importância fundamental. Procurou-se demonstrar que, quando são utilizados pequenos espaçamentos entre eletrodos (menores que quatro metros), particularmente no caso do dipolo-dipolo, é possível a execução de mais níveis de investigação em profundidade (superiores a oito) ainda com uma boa qualidade do sinal. Por outro lado, os arranjos dipolo-dipolo e pólo-pólo permitem um número muito maior de níveis de investigação sem a limitação das pequenas aberturas, mas com alguma perda em definição. Como conseqüência, tem-se um significativo aumento na quantidade de dados gerados na seção, o que contribui para o incremento da resolução bi-dimensional. Outro aspecto testado e avaliado foi o da utilização de múltiplos espaçamentos entre eletrodos sobre o mesmo perfil de levantamento. Este interessante procedimento garante, além de resolução nas porções rasas (graças aos espaçamentos pequenos), o alcance de maiores profundidades de investigação (devido aos espaçamentos maiores) em uma mesma seção. A eficácia desta prática foi verificada tanto na construção das pseudo-seções, como nos modelos geoelétricos gerados pela inversão dos dados (modelagem). A metodologia foi testada em três distintas áreas tendo por objetivo o mapeamento de um nível d´água raso, a determinação da profundidade e conformação de topo rochoso e o mapeamento de uma provável pluma de contaminação. Além de uma ampla revisão bibliográfica sobre o assunto, foi também abordado neste trabalho o controverso tema da profundidade de investigação que de fato se verifica com os arranjos de eletrodos comumente empregados em eletrorresistividade. Procurou-se, com esta tese, contribuir para um melhor entendimento acerca do tema \"imageamento geoelétrico\" e alguns tópicos a ele relacionados, quais sejam: arranjo de eletrodos, procedimentos para se conseguir um bom volume de dados na seção, utilização eficiente do programa de inversão que gera os modelos e, finalmente, a interpretação dos resultados sempre balizada por informações diretas disponíveis e por outros métodos ou técnicas geofísicas de apoio.This paper addresses a detailed, in-depth study on data aquisition, processing and interpretation methodologies for 2D electrical profilings, focusing on investigations oriented to shallow targets. Two-dimensional (electrical profilings) acquisition techniques were used on a wide range of arrays - dipole-dipole, pole-dipole, pole-pole and Wenner arrays - for efficiency comparison purposes. A real 3D acquistion was tested with the pole-pole array in order to check its potential use and limitations. Schlumberger was the array used for SEVs, which helped to interpret and quantify 2D geoelectrical sections, especially as to the vertical distribution of resistivity. The 2D geoelectrical models were generated with an inversion computer program (RES2DINV), which basically corrects any distortions found in the apparent resistivity pseudosections corresponding to the arrays included in this study. These models create images that better match the subsurface geological reality, therefore simplifying the interpretation of results. We tried to explore the full potential use of the inversion computer program for good quality images. The geophysical interpretation was always based on the subsurface information available (boreholes, trenches, wells and outcrop). Resolution is critical in a shallow investigation scale. This study tried to show that the use of small spacings between electrodes (less than four meters), particularly in dipole-dipole arrays, allows for more in-depth investigation levels (greater than eight) without compromising signal quality. On the other hand, dipole-dipole and pole-pole arrays allow for a larger number of investigation levels without small spacings limitations, but with a slight loss of definition. Consequently, there is a significant increase in the amount of data generated at the section, enhancing 2D resolution. Another aspect tested and assessed was the use of multiple spacings between electrodes on the same survey profile. In addition to resolution in shallow sections (thanks to small spacings), this interesting procedure allows deeper investigation levels (due to larger spacings) in the same section. The efficacy of this practice was verified both in the development of pseudo-sections and in the geoelectrical models generated by inversion modelling. The methodology was tested in three different areas in order to map a shallow water table, determine the depth and shape of the bedrock, and map a potential contaminant plume. In addition to the broad literature review available, this paper also covered the controversial topic of depth investigation actually present in electrode arrays typically used in electrical resistivity methods. This thesis tried to provide a better understanding of \"geoelectrical resistivity imaging\" and related topics such as: electrode array, procedures required to generate good volumes of data in the section, efficient use of the inversion computer program behind the models and, lastly, interpretation of results, always based on the subsurface information available and on other supporting geophysical methods or techniques.
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Yamakawa, Yousuke. "Use of an electrical resistivity method together with a combined penetrometer-moisture probe to survey hydrological properties of natural slopes." Kyoto University, 2011. http://hdl.handle.net/2433/142324.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16126号
農博第1862号
新制||農||989(附属図書館)
学位論文||H23||N4596(農学部図書室)
28705
京都大学大学院農学研究科森林科学専攻
(主査)教授 水山 高久, 教授 太田 誠一, 教授 谷 誠
学位規則第4条第1項該当
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Fejfarová, Marie. "Možnosti detekce obsahu vody v pórovitém prostředí metodou elektrické impedanční spektrometrie." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-233811.
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This doctoral thesis with the title “Possibilities of Detecting the Water Content in a Porous Medium Using the Method of Electrical Impedance Spectrometry introduces electrical impedance spectrometry (EIS) as an indirect electrical method of measurement and a tested apparatus for application in water management practice and in material engineering. A wide range of porous media in the area of water management have been narrowed within the preparation of this dissertation thesis to available samples of chiefly sandy soils and in material engineering to typical building materials, which are still solid burnt brick and timber. Measurement took place in the Laboratory of Water Management Research of the Department of Water Structures and in the Laboratory of the Department of Building Materials and Components at the Faculty of Civil Engineering of Brno University of Technology, in the Laboratory of Soil Mechanics of the company GEOtest, a.s. and in the Laboratory of the foreign university KU Leuven, KHBO in the City of Oostende, Belgium. The experiments performed required not only the production of special constructions of measuring probes and their connection, but also modifications of stations at which measurement was carried out. It is possible to use this doctoral dissertation thesis as a methodological manual of how to apply the measuring apparatus based on the EIS method in monitoring changes in the water content in selected porous media due to hydrodynamic stress imposed on it.
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Gimenez, Leandro Maria. "Relação da condutividade elétrica aparente com algumas propriedades físico-hídricas e com a variabilidade espacial dos solos." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/11/11152/tde-17122013-121535/.
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A variabilidade das propriedades físicas do solo apresenta impacto sobre o desempenho das atividades de produção agrícola. Métodos indiretos para obtenção de informações sobre as propriedades do solo com interesse agronômico são utilizados com o intuito de favorecer o uso de insumos de modo mais adequado. A condutividade elétrica aparente do solo (CEa) é influenciada por diversas propriedades, muitas delas interrelacionadas e com variabilidade em curta distância, sendo difícil a separação dos diversos fatores. As medidas de CEa são usualmente tomadas em superfície com arranjos de eletrodos para prospecção de um volume de solo proporcional à distância entre eles. Neste trabalho foi utilizada uma metodologia que permitiu identificar algumas das propriedades com maior impacto sobre a CEa, merecendo destaque aquelas relacionadas ao espaço poroso do solo. A caracterização detalhada da variação da CEa ao longo do perfil do solo e sua comparação com aquela obtida a partir da sondagem elétrica vertical permitiram identificar algumas limitações desta técnica. A presença de camadas com variação de diversas propriedades físicas e de umidade no perfil do solo alterou os valores observados em superfície. A relação entre a distância de separação dos eletrodos no arranjo com quatro pontas igualmente espaçadas, e a profundidade de prospecção, coeficiente k, oscilou entre 0,35 e 0,70 para os solos LVd, LAd e PVe avaliados. A sondagem elétrica empregada na caracterização de variabilidade espacial na horizontal e em profundidade em uma área com teores de argila oscilando entre 150 e 379 g kg-1 na camada 0 a 0,2 m e entre 225 e 326 g kg-1 na camada 0,6 a 0,8 m apresentou resultado satisfatório.The variability of soil physical properties has an impact on the performance of agricultural production activities. Indirect methods for obtaining information on the soil properties with agronomic interest are used to allow the use of inputs more appropriately. The apparent soil electrical conductivity ( ECa ) is influenced by several properties , many of them interrelated and presenting variability in short distances, being difficult to separate the various factors. ECa measures are usually taken in surface, using electrode arrangements for prospecting a soil volume proportional to the distance between them. In this work, a methodology was used that identified some of the properties with the greatest impact on the ECa, with emphasis to those related to soil porous space. The detailed characterization of the variation of ECw throughout the soil profile and its comparison with that obtained from the vertical electrical sounding was carried to identify certain limitations of this technique. The presence of several layers with varying physical properties and moisture in the soil profile changed values obtained from surface sounding. The relationship between the separation of the electrodes in the array with four points equally spaced, the Wenner array, and the depth of exploration, coefficient k, ranged between 0.35 and 0.70 for the soils LVd , LAd PVe and evaluated. A survey was done for the ECa characterization of spatial variability in the horizontal and along soil profile in an area with clay content ranging from 150 to 379 g kg - 1 in the layer from 0 to 0.2 m and between 225 and 326 g kg - 1 in layer 0, 6 to 0.8 m. The use of ECa for characterizing this variability showed satisfactory results.
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Shan, Chunling. "Natural and Controlled Source Magnetotelluric Data Processing and Modeling." Doctoral thesis, Uppsala universitet, Geofysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229917.
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In this thesis, four studies using different geophysical electromagnetic methods are presented. In the first study dealing with airborne measurements, the noise response due to the rotation of the aircraft and the aircraft itself as a metallic conductive body on the Earth's electromagnetic response in very low frequency and low frequency band was investigated. The magnetic fields are independent of the aircraft in the VLF band and part of the LF band. But at higher frequencies (above 100 kHz), the signals are more influenced by the aircraft. The aircraft also generates its own noise frequencies which are mixed with the radio transmitter signals. The second and third studies are applications of radio-, controlled source-magnetotellurics and electrical resistivity tomography methods at a quick-clay landslide site in southwest Sweden. The data are processed and modeled in 2D and 3D, and the models are compared with high-resolution seismic and geotechnical data. The obtained results were further validated and refined by performing synthetic tests in the second study. The third study shows that the 3D models provide larger and more continuous volume of the quick clay structure than traditional 2D models. Both studies have shown that integrated application of geophysical methods for landslides is ideal. Quick clays often overlie the coarse-grained layers showing an increase of resistivity values in the models. In the fourth study, a new audio magnetotelluric data acquisition technique is developed and is named moving magnetotellurics (MMT). In this new technique, the magnetic sensors are placed on the ground and only 15 to 20 minutes data are acquired for each station, which usually is enough to cover the frequency range 30-300 Hz. The new technique is more efficient and convenient than the traditional magnetotelluric method, and test measurements have shown that it is an applicable method in shallow depth studies.
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Xu, Biwen. "Development of electrical resistivity imaging methods for geological and archaeological prospecting." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5540/.
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Rodríguez, Fernández Jesús. "Variación térmica de la resistividad eléctrica en nuevos materiales metálicos: compuestos de tierras raras y aleaciones amorfas." Doctoral thesis, Universidad de Cantabria, 1987. http://hdl.handle.net/10803/22695.
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En la presente memoria se describe el método para la medida de la variación térmica de la resistividad entre 10 y 300 K que hemos puesto a punto en nuestros laboratorios de la Universidad de Cantabria. Dicho método es el de cuatro puntas con corriente alterna y detección síncrona. También se analizan, mediante el método de los elementos finitos, los efectos de la geometría de la muestra y posición de los contactos en la relación entre la resistividad observada experimentalmente y la resistividad real, haciendo hincapié en el caso de muestras anisótropas. Posteriormente aplicamos esta técnica al estudio de diversas series de materiales:
1) Los compuestos RPt que cumplen la Ley de De Gennes y en los que hemos podido determinar los valores de la masa efectiva m* y de la constante de canje.
2) Los compuestos RNi2Si2 en las que se puede observar una relación entre la resistividad magnética y las estructuras magnéticas.
3) Los compuestos CeyLa1-yNixPt1-x, en las que se estudia el efecto Kondo
4) Los amorfos metálicos (Co1-x(Fe5Ni5)x)75Si15B10 en los que se observa un mínimo en la resistividad a bajas temperaturas así como variaciones en lnT, T2 y T a temperaturas bajas, intermedias y altas respectivamenteThe present report describes the method for measuring the temperature dependence of the resistivity between 10 and 300 K that we have developed in our laboratories at the University of Cantabria. This is a four-probe method using ac current and synchronous detection. Also it is analyzed, using the finite element method, the effects of the sample geometry and contacts position in the relationship between the real resistivity and resistivity observed experimentally, even in the case of anisotropic samples. Subsequently we apply this technique to the study of different family of materials: 1) RPt compounds which follow the De Gennes Law, allowing us to determine the values of the effective mass m * and exchange constant. 2) The compounds RNi2Si2 in which it is possible to establish a relationship between the magnetic resistivity and the magnetic structures. 3) The compounds CeyLa1-yNixPt1-x, in which we study the Kondo effects. 4) The amorphous Co1-x(Fe5Ni5)x)75Si15B10 metals, in which there is a minimum in the resistivity at low temperatures as well as variations in LnT, T2 and T at low, intermediate and high temperatures respectively.
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Sayer, Suzanne. "Applications of Roll-Along Electrical Resistivity Surveying in Conjunction with Other Geophysical Methods for Engineering and Environmental Site Characterization." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-01252008-161612/.
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Baines, Christopher David. "Electrical resistivity ground imaging (ERGI), field experiments to develop methods for investigating fluvial sediments." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65086.pdf.
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Khatibi, Asfanjani Danial. "Determination of Homogeneity and Isotropy of Soil Using Geophysical Methods." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171849.
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Cognition of the hydraulic properties of soils is important in civil and environmental projects such as for water supply, geotechnical investigations and evaluation of pollutant spreading. This pilot project aims to develop and test a new method for characterization of the homogeneity and isotropy of different soils by using geophysical measurements. The method is based on geoelectrical (resistivity) measurements using a radial array. Using a radial array with electrode lines in various orientations crossing a midpoint at which water was infiltrated, it was possible to build a 3D-block model showing the water penetration into a soil body. Based on the infiltration pattern it was possible to evaluate the hydraulic heterogeneity and anisotropy of the material. Several common Swedish types of soils were tested. Measurement and evaluation techniques including software were developed. The project shows that geoelectrical measurements using a radial array and geoelectrical instruments available on the market can be used for rapid evaluation of the hydraulic heterogeneity and anisotropy of soils and rock.
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Bäckström, Ann. "Investigation of the correlation of fracture frequency and electric resistivity in impact craters in crystalline rocks." Licentiate thesis, KTH, Land and Water Resources Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1725.
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Impact craters are formed when a large meteorite or comethits the Earth. At the impact a shock wave is released causingabundant fracturing in the surrounding bedrock. This type offracturing is intense and occurs throughout a very large volume(>100 km3) of the bedrock. Fractures of this type have beenobserved in deep drilling, to 5 km depth, in thePuchezh-Katunki Impact Crater. At theses depths the ambienttemperature is high. Thus impact structures are candidates forpotential heat-exchange sources for extraction of geothermalenergy.
There is a relation between fracture intensity and electricresistivity in bedrock predominated by impact-generatedfractures. In crystalline bedrock changes in electricresistivity is mainly due to fracturing which is the mainsource of porosity in these rocks. Electric resistivity methodsare highly sensitivity to porosity. Furthermore highfracture-intensities have generally been associated with lowelectric resistivity. Electro-magnetic methods like Very LowFrequency Resistivity (VLF-R) and Magnetotellurics (MT) canindirectly measure electric resistivity to relatively largedepths in the bedrock.
This study will quantify the relationship between fractureintensity and electric resistivity which can be used as aprospecting tool for geothermal energy resources at largedepth.
To meet that end, a method for fracture mapping on outcropsin Swedish terrain and a method to calculate thethree-dimensional fracture frequency from two-dimensionalfracture data has been developed. The fracture traces measuredin two dimensions on outcrops are assumed to represent avertical surface and must be converted to a three-dimensionalmeasure of the fracture frequency per unit volume. Spacing, dipand trace length of fractures have been accounted for. Thebiases associated with the mapping method have also beenaccounted for (II).
The correlation between impact-induced fracturing andelectric resistivity in crystalline rocks in the Lockne Areashows that the extent of impact fracturing in crystalline rockscan be measured with electro-magnetic or electric techniques.In addition the electric resistivity of crystalline basementand impact generated Tandsby Breccia from the Lockne Craterwere determined (I).
The relation between fracture frequency and electricresistivity in fresh water conditions using the VLF-R method isestablished from data collected from both two drill holes andfrom numerous outcrops in the Björkö region. Apreliminary quantification of the fracture frequency has beenmade. The MT resistivity models, related to the two drillholes, show that porosity and mineral-conductivity variationsof the bedrock affect this relation more than the salinityvariations in the bore-hole fluid. Further research is neededto establish a firm relation between fracture frequency,salinity of rock fluid, conductivity and porosity in order tovalidate the MT resistivity models (III).
Keywords:Electric resistivity, Fracture frequency,Impact generated fractures, Electro-magnetic techniques, VLF-Rmethod, MT method, Window-mapping technique, Three-dimensionalfracture calculations, heat-exchange structure, geothermalenergy.
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Greenwood, Wm Jason. "Mapping porewater salinity with electromagnetic and electrical methods in shallow coastal environments, Terra Ceia, Florida." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000352.
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Gannon, John P. "Evaluation of Fracture Flow at the Coles Hill Uranium Deposit in Pittsylvania County, VA using Electrical Resistivity, Bore Hole Logging, Pumping Tests, and Age Dating Methods." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35179.
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The Coles Hill uranium deposit in Pittsylvania County, VA, is the largest un-mined uranium deposit in the United States. The deposit is located in the Virginia Piedmont in a geologic unit located immediately west of the Chatham Fault, which separates the granitic rocks of the Virginia Piedmont to the west from the metasediments of the Danville Triassic basin to the east. Groundwater at the site flows through a complex interconnected network of fractures controlled by the geology and structural history of the site. In this study groundwater is characterized in a small study area just south of the main deposit. Methods used in this investigation include electrical resistivity profiling, bore hole logging, a pumping test, and age dating and water chemistry. In this thesis groundwater flow is confirmed to occur from the Piedmont crystalline rocks across the Chatham Fault and into the Triassic basin at the study area as evidenced by pumping test data and static water-level data from observation wells. Well logs have identified fractures capable of transmitting water in the granitic rocks of the Piedmont, the Triassic basin metasediments and the Chatham Fault but the largest quantities of flow appear to occur in the Triassic basin. A definable recharge area for the groundwater present at Coles Hill can not yet be determined due to the complexity of the fracture system, but age dating confirms that groundwater is composed of both young and old (>60 years) components, indicating that at least a portion of groundwater at Coles Hill originates from a more distant area.Master of Science
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Tufekci, Sinan. "Combined Surface-Wave and Resistivity Imaging for Shallow Subsurface Characterization." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1250891786.
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Cooper, Marie. "INTEGRATED GEOPHYSICAL METHODS IN INVESTIGATION OF CLAIBORNE AQUIFER HYDROSTRATIGRAPHY, JACKSON PURCHASE, KENTUCKY." UKnowledge, 2016. http://uknowledge.uky.edu/ees_etds/37.
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Increased groundwater withdrawals associated with agricultural irrigation in the Jackson Purchase have prompted questions related to groundwater availability and sustainability. Key factors in addressing these questions are understanding the extent and variation in thickness of the local hydrostratigraphic system, which is the upper part of the Mississippi Embayment aquifer system. Correlations of 70 gamma-ray well logs, and 49 resistivity logs were made across parts of the Jackson Purchase in Fulton and Hickman Counties in order to delineate the upper Claiborne aquifer and middle Claiborne confining unit. Commercial software (i.e. Petra 3.8.3) was used to generate cross sections, structure and isopach maps of the upper Claiborne aquifer, middle Claiborne confining unit, and middle Claiborne aquifer. The structure and isopach maps show the upper Claiborne aquifer and middle Claiborne confining unit thickening and dipping southwest into the embayment. In an effort to test different methods for mapping these hydrostatic units in the shallow sub-surface, surface electrical resistivity and a seismic walkaway sounding were acquired and compared with downhole geophysical logs at two well-constrained sites to test their limits for resolving these hydrostratigraphic units. Both electric resistivity and seismic geophysical methods were best able to image the Claiborne aquifer system when used together.
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Derie, Bereket Mebrahtu. "Integration of geophysical methods for groundwater exploration in hard rock areas : application to Alla Valley, Eritrea, NE Africa." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/12616.
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The integrated use of Electromagnetic Ground Conductivity, Ground Electrical Resistivity and Seismic Refraction geophysics methods was made in Alia valley, Eritrea for the aim of developing a methodology best suited for ground water exploration in hard rock areas with limited professional and financial resources. A total area of 25 square kilometer was covered with the geophysical surveys. The effective use of information from wells and geological information from outcrops and existing literature helped to create a preliminary conceptual hydrogeologic model that in turn provided a general picture of the research site in terms of its groundwater potential and related factors. The optimum configuration of the geophysical methods and their interpretation was researched by the use of synthetic mathematical models and experimental surveys in areas of known hydrogeological characteristics like lithology and depth of water table. Two approximately parallel electromagnetic ground conductivity profile lines crossed the survey area in approximately north-south direction to assess the variation in the electrical conductivity of the major geological structures. Vertical electrical sounding (VES) surveys were conducted close to existing wells with lithological information and at some selected sites. Survey sites for the two dimensional electrical resistivity imaging and the seismic refraction surveys were selected based on the results from the electromagnetic ground conductivity surveys. The formal geophysical surveys results were correlated with nearby boreholes and with each other. The responses of the different geophysical methods for each lithological layer were recognized. In addition, the location and characteristics of the major geological structures of the area were studies based on the information from the geophysical surveys and other available information. At the end of the research, parts of the research area with better groundwater potential were identified. As a result of the research, an efficient and cost effective geophysical approach was developed for groundwater exploration in hard rock areas of Eritrea and similar places of the world. Recommendations were made on the wider and effective use of the approach with due consideration for the limited financial, human resource and material capacities available for ground water exploration in most countries of Africa and other countries of the world.
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Bhamidipati, Raghava A. "Use Of Laboratory Geophysical And Geotechnical Investigation Methods To Characterize Gypsum Rich Soils." UKnowledge, 2016. http://uknowledge.uky.edu/ce_etds/45.
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Gypsum rich soils are found in many parts of the world, particularly in arid and semi-arid regions. Most gypsum occurs in the form of evaporites, which are minerals that precipitate out of water due to a high rate of evaporation and a high mineral concentration. Gypsum rich soils make good foundation material under dry conditions but pose major engineering hazards when exposed to water. Gypsum acts as a weak cementing material and has a moderate solubility of about 2.5 g/liter. The dissolution of gypsum causes the soils to undergo unpredictable collapse settlement leading to severe structural damages. The damages incur heavy financial losses every year.
The objective of this research was to use geophysical methods such as free-free resonant column testing and electrical resistivity testing to characterize gypsum rich soils based on the shear wave velocity and electrical resistivity values. The geophysical testing methods could provide quick, non-intrusive and cost-effective methodologies to screen sites known to contain gypsum deposits. Reconstituted specimens of ground gypsum and quartz sand were prepared in the laboratory with varying amounts of gypsum and tested. Additionally geotechnical tests such as direct shear strength tests and consolidation tests were conducted to estimate the shear strength parameters (drained friction angle and cohesion) and the collapse potential of the soils.
The effect of gypsum content on the geophysical and geotechnical parameters of soil was of particular interest. It was found that gypsum content had an influence on the shear wave velocity but had minimal effect on electrical resistivity. The collapsibility and friction angle of the soil increased with increase in gypsum. The information derived from the geophysical and geotechnical tests was used to develop statistical design equations and correlations to estimate gypsum content and soil collapse potential.
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Yeboah-Forson, Albert. "Hydrogeophysical Characterization of Anisotropy in the Biscayne Aquifer Using Geophysical Methods." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/919.
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The anisotropy of the Biscayne Aquifer which serves as the source of potable water for Miami-Dade County was investigated by applying geophysical methods. Electrical resistivity imaging, self potential and ground penetration radar techniques were employed in both regional and site specific studies. In the regional study, electrical anisotropy and resistivity variation with depth were investigated with azimuthal square array measurements at 13 sites. The observed coefficient of electrical anisotropy ranged from 1.01 to 1.36. The general direction of measured anisotropy is uniform for most sites and trends W-E or SE-NW irrespective of depth. Measured electrical properties were used to estimate anisotropic component of the secondary porosity and hydraulic anisotropy which ranged from 1 to 11% and 1.18 to 2.83 respectively. 1-D sounding analysis was used to models the variation of formation resistivity with depth. Resistivities decreased from NW (close to the margins of the everglades) to SE on the shores of Biscayne Bay. Porosity calculated from Archie's law, ranged from 18 to 61% with higher values found along the ridge. Higher anisotropy, porosities and hydraulic conductivities were on the Atlantic Coastal Ridge and lower values at low lying areas west of the ridge. The cause of higher anisotropy and porosity is attributed to higher dissolution rates of the oolitic facies of the Miami Formation composing the ridge. The direction of minimum resistivity from this study is similar to the predevelopment groundwater flow direction indicated in published modeling studies. Detailed investigations were carried out to evaluate higher anisotropy at West Perrine Park located on the ridge and Snapper Creek Municipal well field where the anisotropy trend changes with depth. The higher anisotropy is attributed to the presence of solution cavities oriented in the E-SE direction on the ridge. Similarly, the change in hydraulic anisotropy at the well field might be related to solution cavities, the surface canal and groundwater extraction wells.
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Magnusson, Mimmi K. "Geoelectrical imaging for interpretation of geological conditions affecting quarry operations." Licentiate thesis, KTH, Land and Water Resources Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9325.
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Determination of the subsurface geology is very important for the rock quarry industry. This is primarily done by drilling and mapping of the surface geology. However in Sweden the bedrock is often completely covered by Quaternary sediments making the prediction of subsurface geology quite difficult. Incorrect prediction of the rock-mass quality can lead to economic problems for the quarry. By performing geophysical measurements a more complete understanding of the subsurface geology can be determined. This study shows that by doing 2D-parallel data sampling a 3D inversion of the dataset is possible, which greatly enhances the visualization of the subsurface. Furthermore the electrical resistivity technique together with the induced polarization method proved to be very efficient in detecting fracture frequency, identification of major fracture zones, and variations in rock-mass quality all of which can affect the aggregate quality. With this technique not only the rock-mass quality is determined but also the thickness of the overburden. Implementation of geophysics can be a valuable tool for the quarry industry, resulting in substantial economic benefits.
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Mokoena, Portia Leah. "Novel approach of using Hydrogeochemistry, Hydrogeologic and Hydrostratigraphic techniques in evaluating coastal aquifers in Heuningnes catchment, South Africa." University of the Western Cape, 2019. http://hdl.handle.net/11394/7960.
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Philosophiae Doctor - PhDThe increasing population in search for better social and economic development in coastal areas puts groundwater resources under pressure because of the high fresh water demand for domestic and agriculture use. Seawater intrusion is widely recognised as major concern in coastal aquifers across the globe and is influenced by multiple factors, being climate variation which is projected to adjust recharge of groundwater because of decreased precipitation patterns and to increase sea level variations and over-abstraction due to high freshwater demand as a result of increased population and agricultural practices, thereby inducing salinization in groundwater. The coastal aquifer in Heuningnes Catchment is not exempted from these issues and salinization is a major concern in the area affecting groundwater quality. In Heuningnes Catchment and South Africa in general there is limited knowledge on the application of integrated approach for assessing groundwater quality especially salinization mechanism in coastal aquifers. The main goal of this research is to test and demonstrate the viability of using joint interpretation approach of geophysics, geochemical and geological information to investigate groundwater quality in coastal aquifers thus improving on the understanding of using such approach. This work offers the initial thorough assessment of groundwater quality and understanding of the salinity sources and hydro-geochemical processes governing the chemical composition of groundwater in the region. Thus provide advice on the fitness of this water for consumption and irrigation purposes. Thirty-two groundwater samples were collected and analysed for (Mg2+), (Ca2+), (Na+), (K+), (Cl-), (SO42), (HCO3-), (pH, TDS and EC). To estimate fitness of groundwater quality for consumption purposes WHO (2011) and SANS241 guideline were used and for irrigation utilization the water quality indices (EC), (Na+%), (SAR), (RSC), (KR) and (MR) were used. Statistics approaches were employed to ascertain the primary geochemical processes governing the chemical composition of groundwater in the research region. Lastly, the spatial distribution maps were created by means of ArcGIS. Electrical resistivity method was used to map the extent of saline distribution within the subsurface. The findings of this study revealed that groundwater in the region is alkaline type and TDS, EC, Na+, Cl- exceeded WHO and SANS241 guidelines for consumption water. The geophysical investigation revealed that the sandy clay/clayey sand, fine sand and fractured sandstone units make up the coastal aquifer systems within the area. Further, revealed that these aquifers were saturated with fresh, saline or brackish water depending on the subsurface layer. The presence of saline and brackish was confirmed by the chemical results which indicated a Na+-Cl- type as a dominant water type. Also classifying groundwater based on EC and TDS supports these findings. The foremost hydro-geochemical processes that controls the salinity and quality of groundwater in the study region as indicated by Gibbs plot are water-rock interaction followed by evaporation process. Furthermore, analysis of hydrochemical data also proposes that weathering of silicate minerals, ion-exchange and dissolution of carbonate minerals amended ion concentration in groundwater thus influencing salinisation in certain parts of the study region. Also assessment of ionic-ratios displays influences of marine sprays as well as seawater, on the chemical structure of groundwater within the Heuningnes Catchment aquifer. Valuation of groundwater quality and its fitness for ingestion and irrigation purposes, the results indicated that shallow groundwater in the area is not suitable for any use; however, groundwater from deeper boreholes was found fresh and appropriate for irrigation and household purposes. Findings of this study indicated that salinity is the major groundwater quality issue for this area and that monitoring of groundwater quality in Heuningnes Catchment is limited. The absence of consistent monitoring program on groundwater quality makes it difficult to ascertain long term trends on groundwater quality parameters. Therefore, this study emphasizes the need for regular groundwater quality monitoring to assess the trends of these parameters in order to make an informed decision as to what can be done for mitigation purposes.
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Ghorbel, Nabil. "Etude sismique et magneto-tellurique du socle et de la couverture sedimentaire dans la partie sud de l'anomalie magnetique du bassin de paris , le val de loire et le nivernais." Paris 6, 1987. http://www.theses.fr/1987PA066395.
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Cette etude permet de distinguer deux types de socle. A l'est de la loire, un type granitique, un profil transversal entre villequiers et beffes montre qu'au passage de l'anomalie le socle forme un horst dont le toit est situe a 1000 m de profondeur environ. A l'ouest de la loire, un socle probablement metamorphique
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Maly, Mascimiliano de Los Santos. "Avaliação da técnica de eletrorresistividade no mapeamento de sedimentos rasos associados a ocorrência de gás no Saco do Mamanguá e na Enseada de Paraty-Mirim." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/21/21136/tde-10102017-174424/.
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A constante pressão exercida sobre os ambientes costeiros por parte das diferentes atividades humanas, em conjunto com novas necessidades relacionadas a estudos ambientais particularmente no que diz respeito à geração de gases de efeito estufa em sedimentos marinhos, têm gerado uma crescente demanda por conhecimento dos processos de geração, acúmulo e liberação desses gases. Dado esse desafio, torna-se necessário o desenvolvimento de novas aplicações de ferramentas geofísicas que forneçam informações além das propriedades acústicas do meio. Dessa forma, o presente trabalho tem como objetivo a avaliação do método eletrorresistivo no mapeamento estratigráfico e na detecção de feições geoelétricas indicativas da presença de gás em sedimentos rasos. Para isso, foram analisadas seções geoelétricas adquiridas no Saco do Mamanguá e na Enseada de Paraty-Mirim por meio da comparação com perfis sísmicos de alta resolução e da medição de resistividade em amostras de sedimentos. Nessas amostras foi simulada a presença de bolhas de gás e analisada a variação da resistividade com a diminuição da salinidade da água intersticial. Observou-se que um volume de bolhas de 0,20% do volume total é suficiente para aumentar em um fator de 1,8 a resistividade de uma amostra saturada em água do mar. Também verificou-se que a resistividade medida é dependente da resistividade da água intersticial. Medidas de susceptibilidade magnética mostraram, neste local, que a variação da resistividade não é devida a variações mineralógicas. As seções geoelétricas mostraram boa correlação com os perfis sísmicos até 9 m de profundidade a partir da superfície da água, onde ocorre uma camada geoelétrica de resistividade <0,35 Ohm.m. Nessa profundidade, observa-se uma interface entre camadas de resistividade elétrica possivelmente causada por uma mudança no teor de água ou de matéria orgânica. Essa interface coincide com o topo da turbidez acústica produzida pela presença de gás.Given the constant pressure exerted over coastal environments by different human activities, in addition to the need for more knowledge concerning environmental issues, particularly with respect to greenhouse gases generation in marine sediments have generated an increasing demand for more information regarding the generation, accumulation and seepage of these gases. Faced with this challenge, there is a necessity to develop new applications to geophysical tools that provide more information than merely the acoustic properties of the medium. This work aims to the evaluation of the geoelectric method in stratigraphic mapping and the detection of geoelectric features of shallow gas. For that purpose, geoelectric sections acquired in the ria of Saco do Mamanguá and Paraty-Mirim were compared with high resolution seismic profiles and resistivity measurements in sediment samples. Presence of gas bubbles inside the sedimentary matrix was simulated and resistivity variation analyzed against the decrease of interstitial water salinity. It was observed that a bubble volume of 0.20% of the total volume is sufficient to increase the resistivity by a factor of 1.8. It was also confirmed that the sample resistivity is dependent on interstitial water resistivity. Magnetic susceptibility measurements showed that resistivity variation is not due to mineralogical variations. The geoelectric sections showed good correlation with the seismic profiles up to 9 m depth from the water surface, where occurs a geoelectric layer of resistivity <0.35 Ohm.m. At this depth, it is observed an interface between resistivity layers possibly caused by a change in water or organic matter content. This interface matches the top of the acoustic turbidity produced by shallow gas occurrences.
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Boubaki, Nerouz. "Détection de cavités par deux méthodes géophysiques : radar de sol et mesures de résistivités électriques." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00855987.
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La détection de cavités en milieu urbain est importante pour prévenir différentes causes d'accidents liés à des possibles effondrements. Les cavités sont aussi des cibles d'intérêts pour les archéologues, car les cavités oubliées sont de potentielles sources de matériel révélant des usages passés. Ces cavités sont de tailles différentes, d'origine anthropique ou non, en milieu extérieur ou sous des bâtiments. Leur taille, ainsi que les propriétés physiques du milieu extérieur dans lequel elles se situent, permettent l'utilisation de différentes méthodes géophysiques. Nous nous sommes concentrés sur l'utilisation de deux méthodes géophysiques, le radar de sol et la tomographie par mesures de résistivité électrique, pour localiser et déterminer les cavités métriques à sub-métrique dans le proche sous-sol (6 premiers mètres). Les mesures de radar de sol sont sensibles aux variations de permittivité diélectrique entre la cavité et le milieu extérieur. Nous montrons par des modélisations numériques un effet sur l'amplitude de la réfléchie en fonction du déport qui permet de discriminer entre une cavité vide et une cavité pleine d'eau. Nous étudions aussi l'amplitude de la réfléchie à incidence normale sur le toit d'une cavité à section carrée en fonction de sa profondeur et de sa taille. Nous mettons en évidence une relation logarithmique profondeur versus taille de cavité pour laquelle l'amplitude de la réfléchie est maximum pour les fréquences de prospection typiques du radar de sol. Par ailleurs nous confirmons qu'alors que les mesures radar permettent de déterminer avec précision les dimensions d'une anomalie dans un sous-sol homogène et peu conducteur, les mesures de résistivité électrique permettent elles de déterminer des zones de hautes résistivités à l'emplacement des cavités. Nous couplons ces deux méthodes géophysiques dans deux études de cas, en utilisant la profondeur des interfaces déterminées sur des radargrammes pour contraindre les modèles de résistivité inversés par l'ajout d'information a priori.
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Yang, Kuang-Chen, and 楊光程. "3D Effect Study of 2D Electrical Resistivity Tomography Method." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/59763127962308352195.
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碩士國立交通大學
土木工程學系
98
Numerical simulation and case study are performed in different 3D earth structures to investigate the possible errors caused by 3D effect. Commercial softwares (EarthImager 3D MOD and EarthImager 3D INV) developed by AGI Ltd. are aimed to simulate the data acquisition and to invert the acquired data. At first, earth models with different situations and alignments were simulated to examine the possible influence caused by 3D effect and to figure out the possible influencing range. Further, a real case was presented to verify the finding from simulations. According to the results of numerical simulations, 3D effect can be observed when the survey line is not perpendicular or parallel to the strike of faults. The main influence is in the ground with high resistivity. With increasing the angle between survey line and the strike of a fault, the influence of 3D effect decreases and can be ignore if the angle is larger than 45 degrees. When the survey line is parallel to the strike of faults, the influencing distance of 3D effect is no more than 3 meters if the survey line is in the ground with lower resistivity, while it is no more than 6 meters if the survey line is in the ground with higher resistivity.
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Wu, In-Gin, and 吳映錦. "Study of Electrical Resistivity Method for Ground Water Table Monitoring." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/c92qs8.
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碩士國立交通大學
土木工程系所
107
The main purpose of this study is to implement electric resistivity technique as a non-destructive geophysical method to investigate the groundwater table level of the unconfined aquifer. Current literatures revealed that the most adopted electric resistivity technique in groundwater table (GWT) investigation is the two-dimensional electric resistivity tomography (2D-ERT) method. However, the inversion scheme used in 2D-ERT may induce various uncertainties during the GWT determination, and the value discrepancy between the inverted apparent resistivity and actual resistivity may be large and unrealistic. On the other hand, the one-dimensional vertical electrical sounding (1D-VES) allows the variations of thickness and resistivity values of each assumed layers, which forms an advantage for this method in the GWT investigation. This study focused at the feasibility assessment of VES in the GWT level monitoring and proposed appropriate inversion parameters according to the study outcomes. This study tackled this issue using numerical simulation, by first defining the scope for a case, where the simulated model consist of a homogeneous layer with GWT at 2.5m. The GWT depth detection performances of both the 2D-ERT and 1D-VES are evaluated through numerical simulation, in order to verify the potential advantage of 1D-VES in this specific task. Upon confirming the forte of 1D-VES, multi-layered strata was next simulated for application testing. However, it was found that for scenarios with numerous local minimums, the resultant outcome from 1D-VES is highly dependent on the given initial parameters, if the commonly used 1D-VES linear inversion approach is adopted for the GWT detection. This led to the difficulty in GWT interface determination and impacted the robustness of 1D-VES. Based on this premise, this study pivoted to a global non-linear inversion algorithm to minimize impact arising from local minimums in conventional 1D-VES. This study adopted simulated annealing optimization approach as the global optimization algorithm in the GWT layer detection. This is performed through forward-modelling the electrical resistivity data and process the simulated data using simulated annealing in Matlab. Four soils with different capillary degree was simulated in this study and appropriate inversion parameters (such as initial guess and search range) were obtained through thorough examination. From the numerical simulation, the impact of capillary phenomenon towards the inverted outcome increases as the GWT becomes shallower. This study therefore sets the simulated GWT level as 2.5m deep for all four simulated soil models. This study attempted to increase the amount of inverted layers in order to mimic the soil resistivity change due to capillary effect. Theoretically, as the inverted layer increases, the capillary phenomenon from above the GWT should be better simulated and resulted in lower error. However, the optimization stability of simulated annealing approach was severely impacted as the amount of inverted layer and inverted parameters increases. Based on the simulated outcome, 3 layers were found as the optimal number of inverted layers, which would reduce inversion error effectively and enhance the outcome stability concurrently. Since simulated annealing approach is computationally expensive and the increment of inverted layers may render this algorithm unstable, this study recommended that the computation enhancement this optimization algorithm could be further improved and other global optimization method could also be evaluated.
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CHEN, CHIH-HUNG, and 鄭智鴻. "Application of Electrical Resistivity Tomography Method to Investigate a DNAPLs Contaminated Site." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/94847133018539514409.
Full textAbstract:
碩士清雲科技大學
空間資訊與防災研究所
100
This study reports the results of using Electrical Resistivity Tomography method to investigate the groundwater and soil in an industrial estate. Chlorinated solvent is one of the raw materials being widely used in the manufacture process of the electronic products for most of the factories located in this industrial estate.Chlorinated solvent is well known to be a Dense Non-Aqueous Phase Liquids (DNAPLs) and may be carcinogenic. So, it is necessary to detect DNAPLs plume in this study area.The purpose of this study is to investigate the situation of contaminated subsurface and to provide the anomalous zones having DNAPLs contamination; simultaneously, combining the ERT results with the groundwater samplings, the distribution and flow direction of pollutants can be recognized. Thus the possible contaminated marker can be pointed out. Fifteen ERT survey lines were conducted around the study site. In addition to 6 previous monitoring contaminated wells, fifteen possible contaminated locations were pointed out and verified by later water samples obtained by well drilling. The highest concentration of trichlorethylene and dichloroethylene in the groundwater sample was over seven times and three times of the maximum levels respectfully. The result indicated that the ERT method could be an effective way to detect the DNAPLs contamination at this site.
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Chiang, Kai-Sheng, and 江凱勝. "Using Electrical Resistivity Imaging method to Investigate Main Hydrogeology in Taichung Basin." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2z947e.
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碩士國立中央大學
地球科學學系
105
This research used Electrical Resistivity Imaging (ERI) method and near geological drilling data to investigated hydrogeology between Datu-Wurih area to Wufong area in the Taichung Basin. The sediments are consisted of unconfined Holocene conglomerate and compact Pleistocene conglomerate in the uppermost 200 m in the Taichung Basin from the drilling data of the Central Geological Survey. We used the Wenner-Schlumberger array in the Taiping alluvial fan and Wurih alluvial fan. We conducted 23 2D Electrical Resistivity Imaging(ERI) measurements and investigated 60m of depth. Compared with near geological drilling data from the observation wells, we found that there was a mud layer with a resistivity lower than 40 Ωm in Taiping alluvial fan near Wurih and Wufong observation wells. On the other hand, in the region with thick conglomerates exhibits resistivity values that are higher than 300 Ωm. In order to delineatethe recharge area which has no insulating mud layers from the resistivity measurements, we used 1D electrical resistivity data for geostatistical spatial modeling, including the krigging and inverse-distance modeling. We compared the 2D resistivity model with drilling data in the basin to show the possible recharge area with thick gravel and conglomerates. The results show that sporadic mud layers only located from the surface to a depth of 60m near the Wurih and Wufong area. Therefore, the majority of the sediments in the Taichung Basin may be consisted of the unconfined conglomerate and serve as the unconfined aquifer in the Taichung basin. The thicker unconfined aquifer where can be natural groundwater recharge area. It can be the alternative water resources for the domestic usage in the future.
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Wu, Ping-Yun, and 吳秉昀. "Investigating Biological Reefs in Guanyin, Taoyuan, by Using Electrical Resistivity Tomography Method." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/z5867h.
Full textAbstract:
碩士國立中央大學
地球科學學系
105
The biological reefs located along the coastal line of Guanyin and Xinwu districts in Taoyuan city is consisted of algal reefs and coral reefs, and also regarded as a big and complete biological reef area in Taiwan. Algal reefs build up extremely slow and expand only 0.9 to 2.3 mm every month; as a result, any investigation in the algal reef area must be implemented very carefully to reduce potential influence in the environment. Because of special electrical property of reefs, it is suitable for applications of electrical exploration methods. The Electrical Resistivity Tomography (ERT) is a fast, non-destructive, and inexpensive surficial geophysical survey method, and therefore it is widely used to investigate reefs. In this study, the location, distribution area and depth of algal reefs were investigated by ERT method to provide a reliable reference of coastal engineering and the establishment of ecosystem refuge. The study area is from the south coast of Fulin river to the south coast of Guanyin river. There are four ERT survey lines, three of them are 960m long and parallel to the shoreline, and the other one is 240m long and perpendicular to others. According to the Archie's Law, the porosity was calculated from the resistivity profile to estimate the depth of reefs beneath each survey line and verify the estimates with the data obtained from borehole core. The results show that the upper boundary of the reefs is 0-1.5m deep (there are sands layer above), and the lower boundary is 4-6m deep (there are conglomerates layer below) in the study area. In addition, all profiles obtained from the north-south survey lines show that the depth of reefs becomes shallower in the range of 100 m in the southernmost end, indicating the southern boundary of the reef distribution in the study area.
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Shieh, Jyh-Shyan, and 謝志賢. "A study of electric structure and depositional environment in Chiayi Coastal Plain by electrical resistivity method." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/58705471078345762099.
Full textAbstract:
碩士國立中央大學
地球物理研究所
87
The direct current resistivity method was used in this study. Two hundred and thirty eight VES wewe carried out between the Peikangchi and the Pachangchi in Chiayi region. Incorporating of the sounding data with the lithological data of wells, the electric characteristics of the formations and the depositional environment are investigated. According to the results, several conclusions are drawn as follows: 1. The results indicate that the study area can be divied into six regions and the strata can be divided into three electric units depending on the electrostratigraphic property. 2. Except the area where close to the foot hills , most of the region was covered by seawater. 3. According to the electrical resistivity, the basal surface of the Holocene formations is induced. The depth to the basal surface ranges from 45 to 55m between Chiayi City and Shinpyi. The depth to the basal surface ranges from 55 to 80m, 80 to 110m, between Shinpyi and Shijou, Shijou and Yihjwu. The depth to the basal surface in Diingtarn ranges from 70 to 85m. 4. Althought the depositional environment of the formations in Pleistocene are similar to that of Holocene. The resistivity of the strata deposited in Pleistocene is higher than that deposited in Holocene in some place. 5. The formations deposited in Holocene have resistivity lower than 20Ω-m indicating which were formed in the marine depositional environment. The resistivity ranges from 20-34Ω-m indicating the formations were formed in the estuarine depositional environment. The resistivity which is higher than 34Ω-m indicates that the formations were formed in the land depositional environment. 6. Most of the study area was belong to estuarine environment for the formations deposited in Holocene . Shoreface and upper shoreface wewe around the Diingtarn,Pwutzzy and Liowjeau areas at that time. Minshyong and Dahlin had been covered by seawater. 7. The position of peikangchi and pachangchi does not differ greatly from that of pre-Holocene.
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chiou, you-hua, and 邱祐華. "Electrical Resistivity Determination of Cement-Based Binder Using Embedded Four-Terminal Probe Method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/05616225872235045354.
Full textAbstract:
碩士國立高雄應用科技大學
土木工程與防災科技研究所
99
This paper uses embedded four-terminal probe method to study the electrical resistivity of cement binders. There are four kinds of materials being investigated including pure cement binders, 15% weight of fly ash mixed, 30% weight of slag mixed, and 1% volume of graphite added cement binders. The resistivities of the cement-binder specimens are measured under unloaded and statically loaded states. For the unloaded tests, the measured volumetric resistivity and the corresponding polarization history are used to observe the hydration degree and early age of the cement-binders. For the statically loaded tests, the resistivity measurements are used to identify the occurrence of fatal damages when specimens are under compressive and flexural loads. The experimental results have shown that the polarization effect would be induced by a constantly applied external electric field, in this study the direct current (DC) input over the outermost electrodes. This effect is prominent at the early age (1 day) of the cement binders and becomes moderate after 7 days of age. It is also observed that the resistivity measurement of cement binders is more consistent after the polarization has reached a plateau, and the saturation period of polarization would decrease with the age of cement binders. Basically, the electrical resistivity also grows with the materials’ age due to hydration process. By adding conductive particles such as graphite powders into the cement mixtures, the resistivity can be effectively lowered. Furthermore, the loading test results have reveal that the materials’ volumetric resistivity would experience a subtle change before any severe damage is induced, and intensively fluctuate when fatal cracks occur. This phenomenon holds true for both the compressive and flexural loading tests.
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Hsu, Fang-Ming, and 許芳鳴. "Use Electrical Resistivity Imaging(ERI) Method to Study the Relationship between Resistivity Structure and Environmental Factors on a Potential Landside Body." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/97y474.
Full textAbstract:
碩士國立中央大學
地球科學學系
103
Because Electrical Resistivity Tomography(ERT) is fast, cheap and accuracy is used to resource exploration and engineering survey, especially disaster prevention. Electrical resistivity survey was carried out continuously for three months to monitor a hazardous hillslope at Jieshou Junior High School in Taoyuan. The monitor site is located at hillslope between the school building and playground. The length of survey line is 67.5 m. The electrode array is alternate array, which is different from traditional array like Wenner array or Dipole-Dipole array. The instrument will measure automatically every day. The study analyzed the data from 2014 June 5 to 2014 September 29. Except ERT profiles of different dates, also calculates the rate of change of resistivity between base model and monitor data, to observe the weak change. Then refer the data from Central Weather Bureau, to discuss the relation between the observed values, rainfall and air temperature. We can observe after heavy rainfall, observed value would decrease, but no obvious change as air temperature change. Through the comparison of inverted sections and rate of change of different time, and comparison of inverted section of real data and synthetic model, we can know the route of infiltration at horizontal coordinate 35 to 45 meters.
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Huang, Chuan-Liang, and 黃傳良. "Electrical Resistivity Method Used to Detect Groundwater Flow – A Case Study of Old Tribe in Lishan." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/3xae76.
Full textAbstract:
碩士國立中興大學
土木工程學系所
100
The substance of this experiment is to estimate the change of groundwater by the change rate of resistivity. Regarding to this experiment, the landslide of Old Tribal in Lishan is inferred from the groundwater. Therefore, owing to the distinguished results of researching the groundwater of the electrical resistivity method, this research is practiced the resistivity in upslope and downslope of drainage well which is made by Soil and Water Conservation Bureau in this area. In this research, to understand the location of groundwater through the cross section, we measured test line of vertical aspect by resistivity in the same lines. There are two differences of test line, one is the changes of amount of rainfall before the construction of drainage well, the other is to observe groundwater in each procedure of construction. Through the differences caused by the results of measuring and the data of investigation of this area then compare with the resistivity to get the route of groundwater and the benefit of project of drainage well. We proved these result, electrical resistivity method is applicable to groundwater research and drainage well effect. Comparing 1D exploration with 2D exploration is better for data interpretation.
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Ding, Yi, and 丁逸. "A study of coastline and stream channels in the north of Tainan by electrical resistivity method." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/73139220136770005833.
Full textAbstract:
碩士國立中央大學
地球物理研究所
87
The locations of the paleo-coastline,the paleo-lagoons and the changes of stream channels in the area between the Pachangchi and the Tsengwenchi streams in northern Tainan are studied in this research by using the direct current resistivity method. Three hundred and sixty-eight vertical electric soundings with the Schlumberger array were conducted in the area between the Peikangchi and the Erhjenchi streams in the Chianan coastal plain .The sounding data were interpreted by the 1-D inversion method . According to the results, several conclusions are drawn as follows: 1. The zone of 10-15 ohm-m is consistent with the zone of steepest gradient of resistivity and salinity. This zone can be regarded as littoral zone. A marine transgression and regression can be recognized by the changes of this zone with depth. 2. A marine transgression occurred from early Holocene till middle Holocene (6-5.3 ka). At the peak of the marine transgression, the coastline reached a line connecting Yensheui, Suchu, Shinghua, and the west of Guanmiauo. The west of the coastline was a paleo lagoon, named the "Chianan Inland Sea" temporarily. The Tzengwenchi stream had been developing westwardly and finally divided the Chianan Inland Sea into two, the Taichiang and the Daufuong Inland Seas, since 6-5.3 ka till recently. 3. The Tzengwenchi stream flowed southwestward through the southern part the Chianan coastal plain as it passed the western foot hills at Guantien, and then flowed into the Chianan Inland Sea in early Holocene. The sedimentation rate in the Daufuong Inland Sea of sediments carried by the Pachang-chi is faster than the Taichiang Inland Sea since 2 ka. From 6-5.3 ka till recently, the Tzengwenchi stream developed westward at the place near Suchu and then developed southwestward forming the recent channel . 4.The development of the Tainan coastal plain,the area between Chishuichi and Yenshuichi streams is mainly influenced by the Tzengwenchi stream since thousands of years ago.
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Jui-ChiLin and 林瑞騏. "Application of Resistivity Image Profiling Method to Understand the Underground Electrical Distribution of Chihshang Fault at Tien-Kuang." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/43802256375806839883.
Full textAbstract:
碩士國立成功大學
地球科學系
102
Taiwan is located between the Eurasian Plate and the Philippine Sea plate, Longitudinal Valley Fault in Taiwan is a common geological structure. Because of creep characteristic, most of geological surveys in this area to date. Chihshang Fault probably has more than one fault line like different branches and small faults. We use “Resistivity” to describe the electrical properties of material and matters. In this study we use digital ground resistivity meter to detect the area at Tien-Kuang in Chihshang in Taitung. Input this survey data, we use an iterative program to output the resistivity model, finally produce resistivity image profile,RIP. We set three lines at Tien-Kuang in this study. Bounded by rupture observed in ditches, in the north is line 107 and 108, the south is line 101. Through the program processing, the thickness of the alluvial layer with high resistivity is about 30 meters in this area. Under this layer is a low resistivity layer. The thickness is about 100 meters. There is an electrical discontinuity about 50 to 60 meters in the west side of this survey lines. These surface rupture should be producing by Chihshang fault when acting.
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Chang, Liang-Chih, and 張良誌. "The investigation of lake-bottom structures with Electrical Resistivity Imaging Method in the Da-hu Lake of Ilan, Taiwan." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/80879045580292523034.
Full textAbstract:
碩士國立臺灣海洋大學
應用地球科學研究所
101
In this study, we used the electrical resistivity method for imaging subsurface structures of the lake bottom sediments in the Da-hu Lake in Ilan, Taiwan. Floating passive electrodes were utilized for the surveys in the study area. We deployed 24 survey lines across the lake, and executed the survey with Schlumberger and Wenner array. There are two geological cores, DH-7A and DH-7B, located at different locations in the Da-hu Lake. The cores were carefully collected for the purpose of the sediment and dating analysis, as well as the geochemical testing for the studies of climate change in the past 10000 years. The inverted images provide good understanding for the spatial relationships of the sediment and basement structures. The sediments above the resistive rock basement are consisted of the sand sediments (from 45 to 60 ohm-m) and mud sediments (20 to 25 ohm-m). The results show that a sandy layer with resistivity of 45 to 60 ohm-m is located at 3 to 8m under the water surface in the east part of the lake, and the outcomes confirm the findings from the DH-7A core data. The resistivity spatial distribution suggests that this sand layer is possibly brought in the lake from the East. We found that a high resistivity layer (>200 ohm-m) at about 5m under the water surface in the south part of the lake, according to outcrops of southern station, that might be the detrital sediments from lakeside to the lake. A sharp linear resistivity structure was found in the west part of the lake. Its strike is consistent to the observations from the surface outcrops of normal fault near the west part of the lake. Consequently, we infer that this structure line might be a stretch of the normal fault and the two cores are located at the hanging wall as well. In addition, the results show we could use the electrical resistivity imaging method with floating passive electrodes to investigate the lake-bottom in details.
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Puntu, Jordi Mahardika, and 嚴精明. "Using Electrical Resistivity Imaging Method to Estimate the Water Table and the Specific Yield of the Unconfined Aquifer: A Case Study along the Wuxi River in the Taichung-Nantou Basin, Central Taiwan." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6e3992.
Full textAbstract:
碩士國立中央大學
地球科學學系
107
The Taichung-Nantou Region is the area with savings of the groundwater, and also with good recharge sources among the groundwater provinces in Taiwan. However, there are only limited observation wells for monitoring the groundwater quantity and quality in the region. In order to provide supplementary measurements for the area, we conducted Electrical Resistivity Imaging (ERI) surveys for time-lapse monitoring of the groundwater level, and also attempt to estimate the hydrogeological parameter. We deployed eleven ERI survey lines with both Wenner and Schlumberger array configurations and conducted the time-lapse measurements 5 times during the year of 2018. Based on the Archie’s Law, we first estimate the relative saturation with the ERI results, then calculate the VG parameters for identifying the water table using the Soil Water Characteristic Curve (SWCC). Lastly, we estimate the theoretical specific yield (Sy) based on the VG model. Our results show that the groundwater level varies between 22.85-m to 51.44-m in the area. In addition, the difference of groundwater level against that measured ones in February is ranging from 1.64-m to 6.52-m. The highest groundwater level took place in July (the wet season) and the lowest groundwater level appears to be in February (the dry season). Moreover, we found that the Sy values are about 0.20-0.26 in the study area, and the lowest Sy value is in the WS02 line.
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Lan, Ping-Hsui, and 藍秉修. "Combined electrical resistivity and ground penetrating radar methods to detect underground pipes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/71545655197773290844.
Full textAbstract:
碩士健行科技大學
土木工程系空間資訊與防災科技碩士班
104
The sewage pipe buried projects were executed in many metropolitan areas to improving economic development and people''s quality of life. Due to the exiting underground pipelines configuration is very complex, we have to determine the correct position of the sewage pipes laying in advance in order to avoid possible damage of the exiting underground pipelines. This study will delineate the distribution of underground pipes by ground penetrating radar and resistivity surveys in the Bade and Taoyuan districts, and figure out the possible misinterpretation the survey results by referring the actual excavation at these sites by the Taiwan Water Supply Corporation, then with the aid of the map data information provides by the pipeline management units, it will reduce the risk of pipeline damage in road excavation. It also provide an available space to installation a new sewage pipe which can reduce the budget of the construction units.
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Shabro, Vahid. "Pore-scale numerical modeling of petrophysical properties with applications to hydrocarbon-bearing organic shale." 2013. http://hdl.handle.net/2152/22902.
Full textAbstract:
The main objective of this dissertation is to quantify petrophysical properties of conventional and unconventional reservoirs using a mechanistic approach. Unconventional transport mechanisms are described from the pore to the reservoir scale to examine their effects on macroscopic petrophysical properties in hydrocarbon-bearing organic shale. Petrophysical properties at the pore level are quantified with a new finite-difference method. A geometrical approximation is invoked to describe the interstitial space of grid-based images of porous media. Subsequently, a generalized Laplace equation is derived and solved numerically to calculate fluid pressure and velocity distributions in the interstitial space. The resulting macroscopic permeability values are within 6% of results obtained with the Lattice-Boltzmann method after performing grid refinements. The finite-difference method is on average six times faster than the Lattice-Boltzmann method. In the next step, slip flow and Knudsen diffusion are added to the pore-scale method to take into account unconventional flow mechanisms in hydrocarbon-bearing shale. The effect of these mechanisms is appraised with a pore-scale image of Eagle Ford shale as well as with several grain packs. It is shown that neglecting slip flow in samples with pore-throat sizes in the nanometer range could result in errors as high as 2000% when estimating permeability in unconventional reservoirs. A new fluid percolation model is proposed for hydrocarbon-bearing shale. Electrical conductivity is quantified in the presence of kerogen, clay, hydrocarbon, water, and the Stern-diffuse layer in grain packs as well as in the Eagle Ford shale pore-scale image. The pore-scale model enables a critical study of the [delta]LogR evaluation method commonly used with gas-bearing shale to assess kerogen concentration. A parallel conductor model is introduced based on Archie's equation for water conductivity in pores and a parallel conductive path for the Stern-diffuse layer. Additionally, a non-destructive core analysis method is proposed for estimating input parameters of the parallel conductor model in shale formations. A modified reservoir model of single-phase, compressible fluid is also developed to take into account the following unconventional transport mechanisms: (a) slip flow and Knudsen diffusion enhancement in apparent permeability, (b) Langmuir desorption as a source of gas generation at kerogen surfaces, and (c) the diffusion mechanism in kerogen as a gas supply to adsorbed layers. The model includes an iterative verification method of surface mass balance to ensure real-time desorption-adsorption equilibrium with gas production. Gas desorption from kerogen surfaces and gas diffusion in kerogen are the main mechanisms responsible for higher-than-expected production velocities commonly observed in shale-gas reservoirs. Slip flow and Knudsen diffusion marginally enhance production rates by increasing permeability during production.text
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Ciou, Jheng-Tang, and 邱正唐. "Application of Electric Resistivity Method to Landslide Survey at University Gulley in Chitou." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/48856957400265223657.
Full textAbstract:
碩士國立臺灣大學
森林環境暨資源學研究所
96
The aim of this study is to investigate the colluvium characteristics using electric resistivity method at University gulley in Chitou. The resistivities and the layer depths can figure the geological and hydraulic condition in this area. The offset errors by the arranged arrays can estimate the lateral resistivity effects in the landslide site. The findings are as follows: 1. Analyzing the resistivity tomography, the accumulated composition in the colluvium is discontinuous and loose. 2. The low resistivity layers, says the subsurface flow or clay layers, found in dry and wet periods may endanger this site in the rain seasons. 3. Investigating from the upper to the lower slopes, the resistivity tomographies and the offset errors show the geological characteristics of debris flow. 4. The offset errors indicate the influence of the heterogenic to the survey is large.
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Ling-RongLiao and 廖伶榕. "Imaging mud fluid conduits of the Gunshuiping mud volcano with Electric Resistivity Methods." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/9g96zm.
Full textAbstract:
碩士國立成功大學
地球科學系
104
We conducted the resistivity survey at the Gunshuiping mud volcano and produced a 3D model in order to delineate the mud-fluid conduits in the mud volcano system. The Gunshuiping mud volcano is located in a 175-m × 90-m platform in Southwest of Taiwan. There are three main mud-volcano craters： craters 1, 2 and 3. Crater 3 is active and the others are inactive. We conducted thirteen survey lines using the Wenner configuration to obtain the resistivity profile images. The lengths of the lines are about 155 m and 60 m, which can resolve the resistivity image down to 30 m and 10 m in depth, respectively. The results showed that there is a vertical structure under the crater 3, and we suggest that it is the mud-fluid conduit. There is a chamber at a depth between 3 and 14 m, and we interpreted that is the temporary storage of mud fluid during the erupting process. Beneath the craters 1 and 2, there is a near-surface, horizontal conduit connecting the craters 1 and 2. At depth between 5 and 12 m, the vertical conduit beneath the north of crater 3 and the horizontal conduit beneath the craters 1 and 2 are connected. The resistivity images clearly delineate the conduit underneath the craters and suggest that the crater 3 is the main erupting conduit, which is consistent to the surface features, in the Gunshuiping mud volcano system.
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Cheng, Hsin-Ju, and 成信儒. "An Analysis of the Spatial Resolution and Resolving Ability of the Surface-Borehole Electrical Resistivity Methods." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/24hjje.
Full textAbstract:
碩士國立中央大學
地球科學學系
107
The non-destructive geophysical investigation methods are widely used in geological surveys, engineering surveys or the composition of the subsurface materials. Especially, because of the high sensitivity of electrical structure, the electrical resistivity tomography method （ERT） has been widely used in near-surface geological surveys, such as hydrogeology groundwater exploration, tunnel engineering, and underground pipelines surveys. Also, combining the surface-borehole electrical resistivity tomography, we will gain more detail of subsurface information from the measured resistivity data. We operated the cross-borehole ERT measurement with the electrode configuration “Hybrid array” at Dapo elementary school locates at Taiwan, Taitung, Chihshang. With 20 electrodes at the surface and the subsurface electrodes of Dapo#2 and Dapo#6. The total data is 3129 and leaves 2300 data after removing the noisy data. Although we get better information at shallow subsurface after the data processing, the information of deeper subsurface is still hard to identify. In order to understand the spatial resolution and resolving ability of ERT method, especially cross-borehole ERT measurement, we should quantify the electrode array and survey parameters before we go field working. So we could efficiently avoid producing the artificial image. This research follows the checkerboard analysis to evaluate the accuracy of inversion results. The forward modeling method and inversion are operated by the ERT software, EarthImager 2D. We choose the electrode configurations Pole-Pole array and Dipole –Dipole array to analyze the spatial resolution and inversion results of surface-borehole ERT. The controlling measure parameter includes electrode spacing, number of wells, the distance of two wells, the grid size of checkerboard, and the structure types.
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Shahroodi, Ahmad. "Development of Test Methods for Assessment of Concrete Durability for Use in Performance-based Specifications." Thesis, 2010. http://hdl.handle.net/1807/25796.
Full textAbstract:
Many Ministry of Transportation of Ontario (MTO) projects consist of construction and maintenance of reinforced concrete structures. Where appropriate test methods exist, MTO has been moving towards use of performance-based specifications for durability control of concrete. MTO currently uses ASTM C1202 (RCPT) coulomb values to assess concrete durability. This test requires taking cores, so replacing this test with a faster non-destructive technique is important.
The main focus of this program was to study the Wenner probe surface resistivity as a non-destructive test device and evaluate the potential for replacement of RCPT with the Wenner resistivity.
This research program consists of the determination of RCPT values, water sorptivity coefficients and electrical resistivities (bulk and surface) of nine concrete mixtures.
In addition, the development of the Wenner probe instrument was studied. As well, correlations between resistivity and ASTM C1202 and C1585 are provided followed by technical recommendations for improving the Wenner test.
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DUBEC, Štěpán. "Analýza průběhu podpovrchových struktur v reprezentativních řezech výzkumných povodí." Master's thesis, 2014. http://www.nusl.cz/ntk/nusl-174240.
Full textAbstract:
This theses is focused on the description of subsurface in the area of interest - Kopaninský and Jenínský stream catchment - and consequently thy most accurate interpretation depth of impermeable bedrock. Geophysical multicable metod (ERT - electrical resistivity tomography") was selected for field measurements. This method of geophysical survey provides the information on subsurface structures, verifies hypotheses and brings new information on the lithological and structural conditions below the surface. ERT measurements were performed automatically by geoelektrical ARES device in combination with inteligent electrodes. The data obtained by field measurements were plotter in the form of resistive sections (using ReS2DInv software) which were used for the later interpretation. The given results determine the depth and process of impermeable bedrock which are important for more accurate data inputs like for modeling rainfall-runoff processes especially in the field of calibration and validation of each adjustment of models as well as for the next other hydrogical analyzes and studies carried out in the research projects. The purpose of this work is to determine the depth of impermeable bedrock and could serve as a data input for MIKE SHE hydrological modeling.
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Vianden, Mitja Johannes. "Zerstörungsfreie Wurzelortung mit geophysikalischen Methoden im urbanen Raum." Doctoral thesis, 2013. http://hdl.handle.net/11858/00-1735-0000-0001-BBD1-B.
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