Marine resistivity tomography for coastal engineering applications in Greece

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. B97-B105 ◽  
Author(s):  
G. Apostolopoulos
Keyword(s):  
Loose Material ◽  
Saline Water ◽  
Coastal Engineering ◽  
High Resistivity ◽  
Geophysical Investigation ◽  
Engineering Applications ◽  
Resistivity Tomography ◽  
Construction Company ◽  
Drilling Data ◽  
Tomography Method

The marine resistivity tomography method can be useful for coastal engineering applications through the use of immersion cables, laid on the water bottom, thus achieving a deeper and more detailed detection of the formations underneath. Careful positioning of the profiles related to the available geologic, geomorphological, bathymetric, and drilling data and to the requirements of engineers, can give thicknesses of loose material as well as the bedrock relief. The formations and their interfaces are clearly defined either by calibration with available drilling data or by high resistivity changes which indicate discontinuities with resistivity values related to permeability and saline water presence. Two case studies are under examination. The first concerns the preservation of an old iron bridge in Lavrion Port with reinforcement and new foundations. Here, the geophysical investigation detects the formation on which the bridge was founded, as well as the loose material above it. The second case study concerns geophysical investigation asked by a construction company for the marine excavation work needed in the new Mesta port. Here, the geophysical measurements with the detected formations give valuable information with respect to the volume of material, equipment, time and cost of excavation as well as where the foundations will be laid for new constructions.

Geological and Geophysical Study in Udheri Khola Area, Nalgad Hydroelectric Project, Jajarkot District, Lesser Himalaya, Western Nepal

2020 ◽  
Vol 22 ◽  
pp. 11-16
Author(s):  
Indra Lamsal ◽  
Subesh Ghimire ◽  
Kamala Kant Acharya
Keyword(s):  
High Resistivity ◽  
Lesser Himalaya ◽  
Geophysical Investigation ◽  
Resistivity Tomography ◽  
Engineering Construction ◽  
Hydroelectric Project ◽  
Geophysical Study ◽  
Karst Feature ◽  
Very High ◽  
Surface Collapse

Subsidence in carbonate rock is one of common and challenging action in terms of engineering construction. Geological study and geophysical investigation carried out in the intake area of Nalgad Hydroelectric Project Jajarkot, western Nepal Lesser Himalaya. The main objective was to identify the cause of subsidence in the intake area of Nalgad Hydroelectric Project, Jajarkot. Geological study of the area was carried to understand the lithology, thickness and structure of the area. The study area comprises two distinct rock units, namely, Dolomite Unit followed up by the Slate Unit. The Dolomite Unit is composed of light grey to grayish white stromatolitic dolomite which is thrusted over the Slate Unit near to Laikham village and Sepu Khola area. The Slate Unit is made up of grayish black to graphitic slate. A thin prominent calcareous horizon wasconfined between Slate Unit. 2D-Electric Resistivity Tomography (ERT) measurements were deployed in four different lines to investigate the cause of the subsidence in the carbonate terrain. A concentric very high resistivity patch shown by Tomogram ER-D-01 survey line was identified and interpreted as dry cavity. The result of the 2D- ERT survey was correlated with core log data of geotechnical exploration in the suspicious point to ensure the presence of karst in the Dolomite Unit at right bank of Nalsyagu Khola near dam axis of Nalgad Hydroelectric Project. The 2D – ERT survey together with geotechnical investigation is capable of identifying subsurface karst feature as the cause of surface collapse in the area.

SIMULATION OF ELECTRICAL MONITORING OF DAMS WITH LEAKAGE WITH A TRANSVERSE PLACEMENT OF THE MEASURING INSTALLATION

2020 ◽  
Vol 8 (4) ◽  
pp. 69-82
Author(s):  
D.S. Rakisheva ◽  
◽  
B.G. Mukanova ◽  
I.N. Modin ◽  
◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Water Level ◽  
Electrical Resistivity Tomography ◽  
Resistivity Tomography ◽  
Measuring Installation ◽  
Basic Functions ◽  
Tomography Method ◽  
Dam Monitoring ◽  
The Mathematical Model ◽  
Measurement Line

Numerical modeling of the problem of dam monitoring by the Electrical Resistivity Tomography method is carried out. The mathematical model is based on integral equations with a partial Fourier transform with respect to one spatial variable. It is assumed that the measurement line is located across the dam longitude. To approximate the shape of the dam surface, the Radial Basic Functions method is applied. The influence of locations of the water-dam, dam-basement, basement-leakage boundaries with respect to the sounding installation, which is partially placed under the headwater, is studied. Numerical modeling is carried out for the following varied parameters: 1) water level at the headwater; 2) the height of the leak; 3) the depth of the leak; 4) position of the supply electrode; 5) water level and leaks positions are changing simultaneously. Modeling results are presented in the form of apparent resistivity curves, as it is customary in geophysical practice.

Pneumatic pulsator design as an example of numerical simulations in engineering applications

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Krzysztof Wołosz ◽  
Jacek Wernik
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Cast Iron ◽  
Numerical Simulations ◽  
Stress Analysis ◽  
Aluminium Alloy ◽  
Loose Material ◽  
Engineering Applications ◽  
Pressure Losses ◽  
Pneumatic Impact

AbstractThe paper presents the part of the investigation that has been carried out in order to develop the pneumatic pulsator which is to be employed as an unblocking device at lose material silo outlets. The part of numerical simulation is reported. The fluid dynamics issues have been outlined which are present during supersonic airflow thought the head of the pulsator. These issues describe the pneumatic impact phenomenon onto the loose material bed present in the silo to which walls the pulsator is assembled. The investigation presented in the paper are industrial applicable and the result is the working prototype of the industrial pneumatic pulsator. The numerical simulation has led to change the piston shape which is moving inside the head of the pulsator, and therefore, to reduce the pressure losses during the airflow. A stress analysis of the pulsator controller body has been carried out while the numerical simulation investigation part of the whole project. The analysis has made possible the change of the controller body material from cast iron to aluminium alloy.

scholarly journals Enhancing Electrical Contact with a Commercial Polymer for Electrical Resistivity Tomography on Archaeological Sites: A Case Study

2020 ◽  
Author(s):  
Marco D. Vásconez-Maza ◽  
Pedro Martínez-Pagán ◽  
Hasan Aktarakçi ◽  
María C. García-Nieto ◽  
Marcos A. Martínez-Segura
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Electrical Contact ◽  
Archaeological Sites ◽  
Resistivity Tomography ◽  
Tomography Method ◽  
Electrical Data

This communication reports an improvement of the quality of the electrical data obtained from the application of electrical resistivity tomography method on archaeological studies. The electrical contact between ground and electrode enhances significantly by using carbomer-based gel during the electrical resistivity tomography measurements. Not only does the gel promote the conservation of the building surface under investigation, but it also virtually eliminates the necessity of conventional spike electrodes, which in many archaeological studies are inadequate or not permitted. Results evidenced an enhancement in the quality of the electrical data obtained in the order of thousands of units compared with those without using the carbomer-based gel. The potential and capabilities of this affordable gel make it appropriate to be applied to other geoelectrical studies beyond archaeological investigations. Moreover, it might solve corrosion issues on conventional spike electrodes, and electrical multicore cables usually provoked for added saltwater attempting to improve the electrical contact.

scholarly journals Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion

Solid Earth ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 75-94 ◽  
Author(s):  
Siobhan F. Killingbeck ◽  
Adam D. Booth ◽  
Philip W. Livermore ◽  
C. Richard Bates ◽  
Landis J. West
Keyword(s):  
Electrical Resistivity ◽  
Saline Water ◽  
Radar Data ◽  
High Resistivity ◽  
Transient Time ◽  
Fractured Bedrock ◽  
Transient Electromagnetic ◽  
Seismic Shear ◽  
Time Domain Electromagnetic ◽  
Ground Penetrating

Abstract. Subglacial water modulates glacier-bed friction and therefore is of fundamental importance when characterising the dynamics of ice masses. The state of subglacial pore water, whether liquid or frozen, is associated with differences in electrical resistivity that span several orders of magnitude; hence, liquid water can be inferred from electrical resistivity depth profiles. Such profiles can be obtained from inversions of transient (time-domain) electromagnetic (TEM) soundings, but these are often non-unique. Here, we adapt an existing Bayesian transdimensional algorithm (Multimodal Layered Transdimensional Inversion – MuLTI) to the inversion of TEM data using independent depth constraints to provide statistical properties and uncertainty analysis of the resistivity profile with depth. The method was applied to ground-based TEM data acquired on the terminus of the Norwegian glacier, Midtdalsbreen, with depth constraints provided by co-located ground-penetrating radar data. Our inversion shows that the glacier bed is directly underlain by material of resistivity 102 Ωm ± 1000 %, with thickness 5–40 m, in turn underlain by a highly conductive basement (100 Ωm ± 15 %). High-resistivity material, 5×104 Ωm ± 25 %, exists at the front of the glacier. All uncertainties are defined by the interquartile range of the posterior resistivity distribution. Combining these resistivity profiles with those from co-located seismic shear-wave velocity inversions to further reduce ambiguity in the hydrogeological interpretation of the subsurface, we propose a new 3-D interpretation in which the Midtdalsbreen subglacial material is partitioned into partially frozen sediment, frozen sediment/permafrost and weathered/fractured bedrock with saline water.

scholarly journals Geophysical study on moraine dam of Imja Glacial Lake in Eastern Nepal using Electrical Resistivity Tomography Method

2018 ◽  
Vol 55 (1) ◽  
pp. 15-22
Author(s):  
Pushpa Raj Dahal ◽  
Kabi Raj Paudyal ◽  
Sudhir Rajaure
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Maximum Depth ◽  
Glacial Lake ◽  
Resistivity Tomography ◽  
Electrical Resistivity Survey ◽  
Geophysical Study ◽  
Glacier Ice ◽  
Tomography Method ◽  
Seepage Channel

Glacial Lake Outburst Flood (GLOF) is one of the potential disaster of Nepal. The Imja glacial lake is considered as one of the fastest growing glacial lake with high risk of GLOF. The internal structure of moraine dams, especially the distribution of buried ice blocks and permafrost materials is key factors in assessing GLOF risk. This study covers exploration and assessment of subsurface conditions of the moraine material such as quantification of buried ice, seepage channel and permafrost material distribution. The geophysical study of dam was carried out by using Dipole–dipole array of Electrical Resistivity Tomography (ERT) method. This study presents the results regarding use of electrical resistivity survey for assessment of the subsurface buried glacier ice and permafrost zones within the dam of the Imja glacial lake. The interpretation of resistivity data at end moraine of Imja glacial lake is based not only on specific resistivity values, but also with field observations and correlation with previous studies. The maximum depth of information obtained from the modeling is about 25 m and; highest and lowest values of resistivity ranges from 117 Wm to 2682240 Wm. The distribution of major subsurface materials from lowest resistivity value to highest resistivity values are classified as saturated moraine (<5000 Wm), frozen moraine (5000 Wm to 20000 Wm) and dead ice (>20000 Wm). The distribution of dead buried ice in moraine dam is found to be heterogeneous. The minimum and maximum depth of dead ice from surface is about 0 m to 20 m at various locations. Based on the information of this study, an open channel was cut through the lake to lower its level and the result is found to be successful. 

Abandoned mine galleries detection using electrical resistivity tomography method over Jharia coal field, India

2017 ◽  
Vol 90 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Prasenjit Das ◽  
S. K. Pal ◽  
P. R. Mohanty ◽  
Piyush Priyam ◽  
Abhay Kumar Bharti ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Abandoned Mine ◽  
Coal Field ◽  
Resistivity Tomography ◽  
Tomography Method ◽  
Jharia Coal

scholarly journals Electrical resistivity tomography applied to geologic, hydrogeologic, and engineering investigations at a former waste-disposal site

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B231-B239 ◽  
Author(s):  
Jonathan E. Chambers ◽  
Oliver Kuras ◽  
Philip I. Meldrum ◽  
Richard D. Ogilvy ◽  
Jonathan Hollands
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Site Investigation ◽  
High Resistivity ◽  
Potential Zone ◽  
Resistivity Tomography ◽  
L2 Norm ◽  
Resistivity Model ◽  
2D And 3D ◽  
2D Resistivity

A former dolerite quarry and landfill site was investigated using 2D and 3D electrical resistivity tomography (ERT), with the aims of determining buried quarry geometry, mapping bedrock contamination arising from the landfill, and characterizing site geology. Resistivity data were collected from a network of intersecting survey lines using a Wenner-based array configuration. Inversion of the data was carried out using 2D and 3D regularized least-squares optimization methods with robust (L1-norm) model constraints. For this site, where high resistivity contrasts were present, robust model constraints produced a more accurate recovery of subsurface structures when compared to the use of smooth (L2-norm) constraints. Integrated 3D spatial analysis of the ERT and conventional site investigation data proved in this case a highly effective means of characterizing the landfill and its environs. The 3D resistivity model was successfully used to confirm the position of the landfill boundaries, which appeared as electrically well-defined features that corresponded extremely closely to both historic maps and intrusive site investigation data. A potential zone of leachate migration from the landfill was identified from the electrical models; the location of this zone was consistent with the predicted direction of groundwater flow across the site. Unquarried areas of a dolerite sill were imaged as a resistive sheet-like feature, while the fault zone appeared in the 2D resistivity model as a dipping structure defined by contrasting bedrock resistivities.

scholarly journals DC resistivity investigation in a fractured aquifer system contaminated by leachate from an old dump

2017 ◽  
Vol 56 (4) ◽  
Author(s):  
César Augusto Moreira ◽  
Carolina Gonçalves Leandro ◽  
Camila Trindade Lopes ◽  
Lenon Melo Ilha
Keyword(s):  
Federal Law ◽  
Fractured Aquifer ◽  
Geophysical Investigation ◽  
Resistivity Tomography ◽  
Aquifer System ◽  
Monitoring Wells ◽  
Sanitary Landfills ◽  
3D Processing ◽  
Environmental Agencies ◽  
2D And 3D

The dumps are areas of final disposal of solid wastes directly into the soil, with no technical criteria or collecting systems of gases or liquids. A large part of Brazilian municipalities have used this extreme damaging alternative to the environment up to the year 2010, when a federal law made compulsory the installation of sanitary landfills. However, large parts of the dumps were simply abandoned, although some eventually go through treatment after assessments of the state environmental agencies. This work presents the results of a geophysical investigation in a dump deactivated in 2004 in a small city in southern Brazil, where previous investigations have revealed contamination of soil and groundwater by leachate. Structural analyzes in the area of study combined to geological data from monitoring wells indicate the presence of contaminants in fractured granite, with a wide variation in the thickness of soil, saprolite and groundwater level. The integration of chemical analyses of the groundwater with electrical resistivity tomography (ERT) in 2D and 3D processing, revealed the existence of large contaminated areas within the limits of the dump flowing into the aquifer partially free up to 5m depth. Such areas may decrease gradually with the increase in depth and between 9m and 19m contaminated zones clearly predominate, associated with the flow in the fractured aquifer. The indication of restricted and oriented zones suggests the targeting and accumulation of contaminants in two systems of preferential fractures. The discovery of these zones is fundamental for planning and the installation of pumping and decontamination systems of groundwater, considering a declining production of leachate since the closure of the dump.

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