scholarly journals Integration of ERT, IP and SP Methods in Hard Rock Engineering

2021 ◽  
Vol 11 (22) ◽  
pp. 10752
Author(s):  
Peng Shao ◽  
Yanjun Shang ◽  
Muhammad Hasan ◽  
Xuetao Yi ◽  
He Meng
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Flow ◽  
Hard Rock ◽  
Geophysical Methods ◽  
Clay Content ◽  
Geophysical Method ◽  
Site Model ◽  
Geotechnical Investigations ◽  
Engineered Structures ◽  
Well Data

Investigation of a hard rock site for the development of engineered structures mainly depends on the delineation of weathered and unweathered rock, and the fractures/faults. Traditionally, borehole tests are used in such investigations. However, such approaches are expensive and time-consuming, require more equipment, cannot be conducted in steep topographic areas, and provide low coverage of the area with point measurements only. Conversely, geophysical methods are non-invasive, economical, and provide large coverage of an area through both vertical and lateral imaging of the subsurface. The geophysical method, electrical resistivity tomography (ERT), can reduce a significant number of expensive drilling tests in geotechnical investigations. However, a geophysical method alone may provide ambiguity in the interpretation of the subsurface, such as electrical resistivity cannot differentiate between water and clay content. Such uncertainty can be improved by the integration of ERT with induced polarization (IP). Similarly, self-potential (SP) can be integrated with other geophysical methods to delineate the groundwater flow. In this contribution, we integrated three geophysical methods (ERT, IP and SP) to delineate the weathered and unweathered rock including the weathered/unweathered transition zone, to detect the fractures/faults, and to map the groundwater flow. Based on ERT, IP and SP results, we develop a geophysical conceptual site model which can be used by site engineers to interpret/implement the findings for build-out. Our approach fills the gaps between the well data and geological model and suggests the most suitable places for the development of engineered structures in the hard rock terrains.

scholarly journals Empirical Correlation between Geotechnical and Geophysical Parameters in a Landslide Zone (Case Study: Nargeschal Landslide)

2018 ◽  
Vol 22 (3) ◽  
pp. 195-204 ◽  
Author(s):  
Sadegh Rezaei ◽  
Issa Shooshpasha ◽  
Hamed Rezaei
Keyword(s):  
Electrical Resistivity ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Geophysical Methods ◽  
Field Investigation ◽  
Least Square ◽  
Geotechnical Investigations ◽  
Geophysical Techniques ◽  
Landslide Zone

Today, geotechnical and geophysical techniques are used for landslide evaluation. Geotechnical methods provide accurate data, but are time consuming and costly. Geophysical techniques, however, are fast and inexpensive, yet their accuracy is lower than that of the geotechnical methods. Therefore, simultaneous use of geotechnical and geophysical methods provides a suitable solution for landslide evaluation. Availability of geotechnical and geophysical data makes it possible to investigate correlation between different parameters. Correlating geotechnical and geophysical parameters ends up lowering field investigation costs and enhancing subsurface survey speed in a landslide zone. In the present study, in order to evaluate Nargeschal landslide in Iran, ambient noise measurement, ERT survey, and geotechnical investigations were used. Once finished with data processing, the data obtained from geotechnical and geophysical investigations were correlated. These included SPT-N – electrical resistivity, soil moisture content – electrical resistivity, and SPT-N – shear wave velocity correlations. The correlations were examined using two methods, namely Spearman’s coefficient test and least square regression analysis. The results obtained from the two methods were in good agreement with one another. The correlations obtained in this study were of moderate to very strong strength and fell in the range of the results of previous studies. Investigation of the results indicated significant influences of ground water on electrical resistivity and soil stiffness on shear wave velocity. Results of this study can be used for soil classification and determination of mechanical and seismic characteristics of soil across various areas.

scholarly journals Geophysical and Geotechnical Investigation for Post Foundation Studies, Faculty of Social Sciences and Humanities, Federal University Oye Ekiti

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Akindeji Fajana ◽  
Olayiwola Olaseeni ◽  
Odunayo Bamidele ◽  
Oladunjoye Olabode
Keyword(s):  
Geophysical Methods ◽  
Low Frequency ◽  
Clay Content ◽  
High Concentration ◽  
Very Low Frequency ◽  
Social Sciences And Humanities ◽  
Building Foundation ◽  
Geological Features ◽  
Geotechnical Investigations ◽  
Clay Formation

A combined geophysical methods involving very low frequency-electromagnetic, electrical resistivity, magnetics prospecting method and geotechnical investigations were used in delineating the causes of cracks on the buildings of Faculty of Social Science and Humanities, Federal University Oye- Ekiti. Five (5) Very Low Frequency-Electromagnetic traverses, Twenty-one (21) Vertical Electrical Soundings and three (3) magnetic profiles were occupied and investigated around the distress building. Two (2) locations were also occupied for geotechnical investigations. Three major layers were delineated in the study area which includes the topsoil, weathered/fractured layer and fresh basement. The VES curve types obtained were A, H, K and Q curves. The buildings were found to be situated within the area of a fairly high concentration of fractures that can aid subsidence in the area and relatively low resistivity zones typical of incompetent clay formation. The geotechnical results also show that the soil has relatively high clay content. Based on the consistency limits. The soils within the area is classified as medium plasticity, hence, the soils are expected to exhibit medium swelling potential. It can however be concluded that the subsoils on or within which buildings are founded within the study area are not competent. From the result, the building failure observe as cracks and foundation subsidence may have been caused by the foundation soils that made up of incompetent materials (clay) which could compress on imposing loads by differential settlement. It is noteworthy that geological features such as fractures/faults delineated within the bedrock is also inimical to the building foundation.

scholarly journals DELINEATION OF AQUIFEROUS ZONES USING GEOPHYSICAL METHODS AND CONTAMINANT FLOW DIRECTION -A case study of dumpsite at Cassidy, Okokomaiko, LASU-Badagry Expressway, Lagos State, Nigeria

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Rafiu Adegbola ◽  
Olanike Abidoye ◽  
Ibrahim Adaranijo
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Flow ◽  
Flow Direction ◽  
Geophysical Methods ◽  
Electrode Array ◽  
Unconfined Aquifer ◽  
Near Surface ◽  
The North ◽  
Lagos State ◽  
Groundwater Flow Direction

Introduction: Cassidy area, of Okokomaiko, Ojo, Lagos State, is a rapidly developing area with attendant growing population arising from the presence of University, financial institutions and popularly known Alaba market. Unfortunately, water supply by the water corporation is not readily available. The inhabitants only rely on the surface water and groundwater extracted from hand dug wells and boreholes. Aims: The study is to map the aquiferous zone and establish the groundwater flow direction, with a view to averting subsurface contamination emanated from dumpsite within the area. Materials and Methods: Twenty five (25) Vertical Electrical Sounding (VES) using Schlumberger electrode array, four (4) Electrical Resistivity imaging using Wenner Electrode Array were acquired at four different traverses. Manual groundwater flow direction was also conducted. Results: The identified unconfined aquifer was sand/sandy clay which is overlain by peat/clay soil that is loose and may allow downward migration of the contaminant plumes to deep groundwater. However, the confined aquifer observed to occur approximately at depth 18 m. The electrical resistivity distribution observed decreases upward, south and north. This implies increase in conductivity in such directions and as such indicating the contaminant could be more concentrated near-surface, north and south. Conclusion: The implication of the results obtained with respect to vulnerability to groundwater pollution is that the southern section of the aquifer is more susceptible to receive transported contaminants from the northern part of the study area. The study suggests the potential borehole should be sited in the north-eastern direction with the aid of geophysical survey.

scholarly journals Identification, Monitoring, and Assessment of an Active Landslide in Tavan-Hauthao, Sapa, Laocai, Vietnam – A Multidisciplinary Approach

2021 ◽  
Vol 16 (4) ◽  
pp. 501-511
Author(s):  
Manh Duc Nguyen ◽  
Nguyen Van Thang ◽  
Akihiko Wakai ◽  
Go Sato ◽  
Jessada Karnjana ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Geophysical Methods ◽  
Standard Penetration Test ◽  
The Road ◽  
Geotechnical Characteristics ◽  
Ground Survey ◽  
Geotechnical Investigations ◽  
Active Landslide ◽  
Ancient Rock ◽  
Geologic Condition

The active landslide located in the Tavan-Hauthao, Sapa district, Laocai province, Vietnam was investigated using geophysical methods (2D Electrical Resistivity and Tomography), geotechnical investigations, and a ground survey to assess the geologic condition of the sliding block and surrounding ground. Landslide displacement was measured using 15 surface monitoring points. Numerical modeling was done to assess the behavior of an active landslide. This multi-disciplinary approach helped in interpreting landslide stratigraphy, geotechnical characteristics of the sliding groundmass, depth, and nature of the sliding plane. The surface area of the slide is approximately 1200 m2. Studying this active landslide is important as it affects the road No. 152, which is an important road connecting the Sapa Ancient Rock Field. This study involved surface topographical survey, surface and sub-surface geological, and geotechnical investigations including Standard Penetration Test and Electrical Resistivity Tomography. Geologic and geotechnical data were used to characterize an active landslide block, which is composed of different soil layers underlaid by granitic rock. The surface electrical-resistivity measurements across the Sapa landslide resulted in inverted-resistivity sections with distinct resistivity contrasts that correlated well with the geology and geo-hydrology observed in boreholes.

scholarly journals Geophysical methods to assess soil characteristics

2021 ◽  
pp. 139-174
Author(s):  
Ho-Chul Shin ◽  
◽  
Guillaume Blanchy ◽  
Ian Shield ◽  
Peter Fruen ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Organic Matter ◽  
Agricultural Soils ◽  
Geophysical Methods ◽  
Organic Matter Content ◽  
Clay Content ◽  
Soil Characteristics ◽  
Matter Content ◽  
Soil Physical Characteristics ◽  
Seismic Coupling

This chapter explores the use of geophysical methods to assess soil physical characteristics. The chapter begins by reviewing the geophysical properties of soil, such as clay content and organic matter content. It then moves on to discuss the electromagnetic induction method and its application, then examines electrical resistivity and its application. Acoustic-to-seismic coupling is also reviewed in terms of creating a model and its application. The chapter concludes by providing an overview of the several geophysical methods that can be used to measure various characteristics of agricultural soils.

Geotechnical investigation through SP, Electrical Resistivity and GPR geophysical methods

Geotecnia ◽  
2016 ◽  
Vol 137 ◽  
pp. 141-155
Author(s):  
Herson Oliveira da Rocha ◽  
◽  
Lúcia Maria Costa e Silva ◽  
João Andrade dos Reis Júnior ◽  
◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Geophysical Methods ◽  
Geotechnical Investigation

scholarly journals Characterization of a Shallow Coastal Aquifer in the Framework of a Subsurface Storage and Soil Aquifer Treatment Project Using Electrical Resistivity Tomography (Port de la Selva, Spain)

2021 ◽  
Vol 11 (6) ◽  
pp. 2448
Author(s):  
Alex Sendrós ◽  
Aritz Urruela ◽  
Mahjoub Himi ◽  
Carlos Alonso ◽  
Raúl Lovera ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Water Reuse ◽  
Electrical Resistivity Tomography ◽  
Groundwater Modeling ◽  
Geophysical Methods ◽  
Soil Aquifer Treatment ◽  
Modeling Tools ◽  
Resistivity Tomography ◽  
Implicit Modeling ◽  
The Difference

Water percolation through infiltration ponds is creating significant synergies for the broad adoption of water reuse as an additional non-conventional water supply. Despite the apparent simplicity of the soil aquifer treatment (SAT) approaches, the complexity of site-specific hydrogeological conditions and the processes occurring at various scales require an exhaustive understanding of the system’s response. The non-saturated zone and underlying aquifers cannot be considered as a black box, nor accept its characterization from few boreholes not well distributed over the area to be investigated. Electrical resistivity tomography (ERT) is a non-invasive technology, highly responsive to geological heterogeneities that has demonstrated useful to provide the detailed subsurface information required for groundwater modeling. The relationships between the electrical resistivity of the alluvial sediments and the bedrock and the difference in salinity of groundwater highlight the potential of geophysical methods over other more costly subsurface exploration techniques. The results of our research show that ERT coupled with implicit modeling tools provides information that can significantly help to identify aquifer geometry and characterize the saltwater intrusion of shallow alluvial aquifers. The proposed approaches could improve the reliability of groundwater models and the commitment of stakeholders to the benefits of SAT procedures.

scholarly journals Innovative Hydrogeophysical Approaches as Aids to Assess Hungarian Groundwater Bodies

2021 ◽  
Vol 11 (5) ◽  
pp. 2099
Author(s):  
Péter Szűcs ◽  
Norbert P. Szabó ◽  
Mohammad Zubair ◽  
Sándor Szalai
Keyword(s):  
Geophysical Methods ◽  
Shallow Groundwater ◽  
Clay Content ◽  
Management Plan ◽  
Statistical Interpretation ◽  
Multivariate Statistical ◽  
Joint Application ◽  
Shallow Groundwater Table ◽  
Horizontal Variations ◽  
Resistivity Log

The Hungarian water management plan has lately identified 185 groundwater bodies based on the concepts given by the European Water Framework Directive. Achieving and maintaining the good quantitative and chemical status of these groundwater bodies is of primary importance. It is demonstrated how innovative hydrogeophysical methods can be applied successfully to assess the Hungarian or other international groundwater bodies. By applying geoelectric methods, horizontal layering or large uniform rock units can be well characterized by Wenner–Schlumberger array, also enabling accurate depth determination of the shallow groundwater table. Horizontal variations in the rock type or its state can be well described by dipole–dipole array or, even better, by the newly developed quasi-null arrays. Their joint application may be very straightforward to investigate different aquifer types by giving high-resolution resistivity images as input for hydrogeological modeling. In the identification of porous formations, multivariate statistical interpretation of wireline logs using cluster analysis allows reliable lithological separation of potential aquifers. Their clay content is estimated by robust factor analysis, while their hydraulic properties are directly derived from the resistivity log. For a more effective interpretation, a combination of surface and borehole geophysical methods can be recommended for meeting challenges in hydrogeology and groundwater management.

Investigating the Effective Resistivity of Reinforced Concrete Waste Storage Tanks at the Hanford Site

Geophysics ◽  
2021 ◽  
pp. 1-50
Author(s):  
Allan Haas ◽  
Dale F. Rucker ◽  
Marc T. Levitt
Keyword(s):  
Electrical Resistivity ◽  
Reinforced Concrete ◽  
Geophysical Methods ◽  
Underground Storage ◽  
Storage Tanks ◽  
Hanford Site ◽  
Underground Storage Tanks ◽  
Effective Resistivity ◽  
Geophysical Surveys ◽  
Wide Range

Industrialized sites pose challenges for conducting electrical resistivity geophysical surveys, as the sites typically contain metallic infrastructure that can mask electrolytic-based soil and groundwater contamination. The Hanford site in eastern Washington State, USA, is an industrialized site with underground storage tanks, piping networks, steel fencing, and other potentially interfering infrastructure that could inhibit the effectiveness of electrical resistivity tomography (ERT) to map historical and monitor current waste releases. The underground storage tanks are the largest contributor by volume to subsurface infrastructure and can be classified as reinforced concrete structures with an internal steel liner. Directly measuring the effective value for the electrical resistivity of the tank, i.e., the combination of individual components that comprise the tank’s shell, is not reasonably possible because they are buried and dangerously radioactive. Therefore, we indirectly assess the general resistivity of the tanks and surrounding infrastructure by developing synthetic ERT models with a parametric forward modeling study using a wide range of resistivity values from 1×10−6 to 1×104 ohm-m, which are equivalent to steel and dry rock, respectively. The synthetic models used the long-electrode ERT method (LE-ERT), whereby steel cased metallic wells surrounding the tanks are used as electrodes. The patterns and values of the synthetic tomographic models were then compared to LE-ERT field data from the AX tank farm at the Hanford site. This indirect method of assessing the effective resistivity revealed that the reinforced concrete tanks are electrically resistive and the accompanying piping infrastructure has little influence on the overall resistivity distribution when using electrically based geophysical methods for characterizing or monitoring waste releases. Our findings are consistent with nondestructive testing literature that also shows reinforced concrete to be generally resistive.

scholarly journals Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1685-1705
Author(s):  
Silvia Salas-Romero ◽  
Alireza Malehmir ◽  
Ian Snowball ◽  
Benoît Dessirier
Keyword(s):  
Large Scale ◽  
Geophysical Methods ◽  
Hydrological Modelling ◽  
P Wave ◽  
Coarse Grained ◽  
Near Surface ◽  
Reflection Seismic ◽  
Geotechnical Investigations ◽  
Quick Clay ◽  
Near Surface Geophysics

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

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