Resistivity imaging technique to delineate shallow subsurface cavities associated with old coal working: a numerical study

Das, Prasenjit; Mohanty, Priya Ranjan

doi:10.1007/s12665-016-5404-0

Cited by 15 publications

(6 citation statements)

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“…The detection of subsurface structure using the resistivity method is mainly dependent on resistivity contrast, which may constrain the inverted model resolution [16]. We used different resistivity perturbations (±20%, 40%, 60%, and 80%) to examine array (DD, PD, WS, and PP) sensitivities.…”

Section: Sensitivity To Resistivity Contrastsmentioning

confidence: 99%

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Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities

2021

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We examined the uncertainty of the two-dimensional (2D) resistivity method using conceptual cavity models. The experimental cavity study was conducted to validate numerical model results. Spatial resolution and sensitivity to resistivity perturbations were also assessed using checkerboard tests. Conceptual models were simulated to generate synthetic resistivity data for dipole-dipole (DD), pole-dipole (PD), Wenner–Schlumberger (WS), and pole-pole (PP) arrays. The synthetically measured resistivity data were inverted to obtain the geoelectric models. The highest anomaly effect (1.46) and variance (24,400 Ω·m) in resistivity data were recovered by the DD array, whereas the PP array obtained the lowest anomaly effect (0.60) and variance (2401 Ω·m) for the shallowest target cavity set at 2.2 m depth. The anomaly effect and variance showed direct dependency on the quality of the inverted models. The DD array provided the highest model resolution that shows relatively distinct anomaly geometries. In contrast, the PD and WS arrays recovered good resolutions, but it is challenging to determine the correct anomaly geometries with them. The PP array reproduced the lowest resolution with less precise anomaly geometries. Moreover, all the tested arrays showed high sensitivity to the resistivity contrasts at shallow depth. The DD and WS arrays displayed the higher sensitivity to the resistivity perturbations compared to the PD and PP arrays. The inverted models showed a reduction in sensitivity, model resolution, and accuracy at deeper depths, creating ambiguity in resistivity model interpretations. Despite these uncertainties, our modeling specified that two-dimensional resistivity imaging is a potential technique to study subsurface cavities. We inferred that the DD array is the most appropriate for cavity surveys. The PD and WS arrays are adequate, while the PP array is the least suitable for cavity studies.

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Section: Sensitivity To Resistivity Contrastsmentioning

confidence: 99%

“…Several geophysical methods are applied in order to determine the size, position, and depth of the subsurface cavities. Among the geophysical methods, resistivity imaging is a commonly used technique to identify cavity structures [12,[14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities

2021

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“…The literature published in the past revealed that various researchers used the ERT technique very effectively to delineate sinkholes, potholes, old abandoned goaves, cavities, voids, underground galleries/workings and so on (Abu-Shariah, 2009;Das & Mohanty, 2016;Das et al, 2017;Ortega et al, 2010;Van Schoor, 2002;Zhou et al, 2004;Bharti, Pal, Priam, Kumar, et al, 2016;Bharti, Pal, Priam, Pathak, et al, 2016;Bharti et al, 2016c;Arjwech et al, 2021;Barbosa et al, 2020;Bharti et al 2021;Bhattacharya & Shalivahan, 2016;Fargier et al, 2017;Nthaba et al, 2020;Prosdocimi et al, 2019;Samanlangi, 2018;Bharti, Prakash, et al, 2022). A recent study by Saurabh et al (2020) is worth mentioning as it relates to old mine belowground workings across railway tracks in Eastern Coalfields Ltd.…”

Section: Introductionmentioning

confidence: 99%

Electrical resistivity tomography technique coupled with numerical modelling: A case study for stability analysis

Bharti

Singh

Pal

et al. 2023

Geophysical Prospecting

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Cavity due to underground old mine workings is one of the major threats to the coal mines and the overlying subsurface and surface properties, which need to be protected. The detection of old mine workings and stability assessment of overlying strata are common problems in most of the Indian coalfields. Several coal mines in India are loss‐making, mainly due to different types of mine hazards. Khandra mine is one such mine at Raniganj Coalfield, Eastern Coalfields Ltd., a subsidiary of Coal India Limited. In the present study, 2‐dimensional and 3‐dimensional electrical resistivity tomography were carried out for detailed subsurface characterization. It supports delineating underground workings, including the nature of voids/cavities (air or water‐filled). Excessive distortions were reported in electrical resistivity tomography application, especially at the near‐surface, owing to large resistivity variations. Refinement of the model by half‐unit electrode spacing was attempted here to reduce the distortions with minimum possible absolute errors. 3‐Dimensional resistivity volumetric model was also developed with the help of five electrical resistivity tomography parallel profiles for better apprehension of the subsurface. Analysis provided important inputs for stability analysis using 3‐dimensional numerical modelling. The physico‐mechanical properties of the overlying strata, pre‐excavation in situ stresses, boundary conditions and the mine geometry simulation were incorporated for understanding the stability analysis. Stability analysis was carried out using the finite difference technique. The analysis of 3‐dimensional numerical modelling indicated that two distinct layers comprising (i) laterite/part of the course to medium‐grained sandstone and (ii) developed galleries of R‐IX seam exhibited a very low safety factor below 1.0, indicating potholing/subsidence susceptibility. The other three layers comprising parts of fine‐grained sandstone exhibited a relatively higher safety factor of around 2.0, indicating moderately stable zones, but not on a long‐term basis. Parts of Siduli stream embankments need suitable retaining walls to avoid water inundation for the stability of the area.

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“…e mining subsidence and surface damage in this gully area are dynamic and changing. Understanding the mechanisms involved in gully slope landslides, subsidence, and other geological disasters under the conditions in this large mining area is critical for predicting surface damage and developing methods for controlling these disasters [36][37][38]. Compared with other coal seam mining areas, the bedrock in the gully area is thinner and the cementation is poor.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Changes in Surface Damage Induced by High‐Intensity Mining of Shallow, Thick Coal Seams in Gully Areas

2020

Advances in Civil Engineering

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is study proposes a novel approach to study the mechanism of mining and dynamic changes in surface subsidence and geological hazard-prone regions caused by shallow, thick coal seam mining in gully areas. is approach combines field observation, threedimensional modeling, numerical simulation, and theoretical analysis based on the conditions of the Chuancao Gedan coal mine. e in situ stress field of coalbeds is influenced by the gully terrain. Shear stress becomes concentrated on the surface, causing geological disasters such as landslides and collapse of gully slopes. High-intensity mining activities increase the concentration and are more likely to cause such geological disasters. e influence area and severity vary dynamically with the expansion of the excavation area. With the continuous expansion of coal seam mining, the amplification ratio η (the ratio of the maximum impact range of surface subsidence and the mined-out area) first increased to 3.35, then decreased, and finally reached a constant value of 2.1. e principle of road line selection is proposed based on an analysis of surface subsidence and gully slope stability on the goaf edge. e principle of subsection reinforcement of the gully slope under the dynamic influence of coal seam mining is also determined.

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Resistivity imaging technique to delineate shallow subsurface cavities associated with old coal working: a numerical study

Cited by 15 publications

References 50 publications

Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities

Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities

Electrical resistivity tomography technique coupled with numerical modelling: A case study for stability analysis

Dynamic Changes in Surface Damage Induced by High‐Intensity Mining of Shallow, Thick Coal Seams in Gully Areas

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