Enhancing understanding of breakdown and collapse in the Yorkshire Dales using ground penetrating radar on cave sediments

Murphy, Phillip J.; Westerman, Anthony Robin; Clark, Roger A.; Booth, Adam; Parr, A.

doi:10.1016/j.enggeo.2007.11.015

Cited by 12 publications

(7 citation statements)

References 6 publications

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“…Inspection of Table 4 reveals that the computation of models with a total number of blocks greater than several thousands is very time consuming with a single 3 GHz processor, for example a CPU time of 138 h is required for the largest computer model (10). The obtained average number of iterations per time step, a measure of the efficiency of the numerical convergence and the adequacy of the selected numerical control parameters, is very reasonable.…”

Section: Results Of Numerical Analysismentioning

confidence: 91%

“…[18]] or collapse without preliminary warning with the failure zone breaking the ground surface [e.g. [10]]. …”

Section: Introductionmentioning

confidence: 99%

“…The collapse of underground karst caverns due to excessive spans or insufficient rock cover is a major geological hazard in rock masses that are prone to the risk of sinkhole development [1][2][3][4][5][6][7][8]; accordingly, much research has been conducted recently on the detection of karstic caverns at depth using different geophysical methods [9][10][11][12] with various levels of success. Analytical solutions for the stability of shallow underground caverns in blocky rock masses are rarely used because of the inherently discontinuous nature of the problem; instead, numerical approaches such as the finite element [13], discrete element [14], or hybrid [15] methods of analysis are typically employed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stability of shallow karstic caverns in blocky rock masses

Hatzor

Wainshtein

Mazor

2010

International Journal of Rock Mechanics and Mining Sciences

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Section: Results Of Numerical Analysismentioning

confidence: 91%

“…[18]] or collapse without preliminary warning with the failure zone breaking the ground surface [e.g. [10]]. …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stability of shallow karstic caverns in blocky rock masses

Hatzor

Wainshtein

Mazor

2010

International Journal of Rock Mechanics and Mining Sciences

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“…on changing the orientation of antennae with respect to the above-surface feature), because they would still destructively interfere on application of stacking. This parallels the approach of Murphy et al (2008), who used velocity-based methods to suppress air-wave energy reflected around the walls of a narrow cave, when reflections from underlying sediments were obscured.…”

Section: Noise Suppression Algorithmsmentioning

confidence: 77%

Multi‐offset ground penetrating radar methods to image buried foundations of a medieval town wall, Great Yarmouth, UK

Booth

Clark

Hamilton

et al. 2010

Archaeological Prospection

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In conventional common-offset (CO) usage, ground-penetratingradar (GPR) methodsmay be problematic where a target is hosted within a structurally complex subsurface, or where coherent noise energy obscures the response to that target. This often occurs when imaging archaeology in urban environments, where reflected and diffracted air-wave energy can be pervasive in the presence of cars, walls and other nearby features.To overcome such issues we show a multi-offset (MO) GPR approach to urban surveying. Multi-offset velocity analysis is used as a filter by which ground-propagating signal energy is separated from airborne arrivals, with the latter suppressed on application of normal moveout corrections and stacking. Pre-stack migration is applied and yields considerable improvement to target resolution compared with post-stack routines. The MO-derived model of GPR velocity can also show the subsurface distribution of archaeological layering. Methods are demonstrated for a 25-fold MO GPR profile acquired, using unshielded antennas of 200 MHz centre-frequency, over foundations of the medieval town wall of Great Yarmouth, UK. The buried foundations represent a vertical discontinuity in the ground, which truncates both natural geological and archaeologically prospective layers.In addition to this complexgeometry, whichitself hinders GPRimaging, coherent air-wave noise is problematic because there are numerous above-surface features (e.g. parked cars, abovesurface walls) in the immediate vicinity of the profile. The improvement offered by MO techniques is benchmarked against a conventional CO routine and compared with co-located borehole records for a comprehensive subsurface interpretation.Target foundations appear ca.1.5 m beneath the ground surface, and GPR data support artefactual evidence of the construction of a sixteenth century rampart on their interior side. Despite the increased survey effort, werecommend MOmethods at anylocationwhere CO data are dominatedwith coherent noise energy, andwhere complex subsurface geometries degrade the output from standard migration algorithms.

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“…Detection of hazardous cavities, subsidence sinkholes, and sagging in karst terrain as potential geohazard assessment is necessary particularly in populated sites. Recently, several studies have successfully applied the GPR method with other geophysical surveys and techniques in order to evaluate and predict the risk of sinkhole collapses in urban areas (Murphy et al, 2008;Delle Rose & Leucci, 2010;Gomez-Ortiz & Martín-Crespo, 2012;Carbonel et al, 2014;De Giorgi & Leucci, 2014;Pueyo-Anchuela et al, 2015). Karst cavities are also investigated by the GPR to prevent geohazards in mineral exploitation (Zajc et al, 2014;Zajc et al, 2015).…”

Section: The Ground Penetrating Radar Methodsmentioning

confidence: 99%

Search for an artificially buried karst cave entrance using ground penetrating radar: a successful case of locating the S-19 Cave in the Mt. Kanin massif (NW Slovenia)

Gosar¹,

Čeru²

2016

IJS

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Abstract:The S-19 Cave was with its explored depth of 177 m one of the most important caves of the Mt. Kanin massif, but after its discovery in 1974, a huge snow avalanche protection dyke was constructed across the cave entrance. To excavate the buried cave, the accurate location of the cave had to be determined first. Since the entrance coordinates were incorrect and no markers were available, application of geophysical techniques was necessary to do this. A Ground Penetrating Radar (GPR) with special 50 MHz rough terrain antennas was selected as the single suitable geophysical method for the given conditions where thick debris overlay a rugged limestone surface. Nevertheless, it was not possible to directly detect the relatively narrow cave entrance itself due to data resolution limits. However, a historical photo of the area showed that the cave entrance was located in a local depression, which therefore represented the main target of the GPR survey. Seven GPR profiles were measured across the rough and steep surface causing difficulties in traversing the area with sensitive research equipment. In all recorded radargrams a small depression was clearly imaged under debris, and recognized as a topographic feature with the cave entrance. Based on the GPR data interpretation, the exact location for digging was determined and the thickness of debris assessed at 6.5-7 m. A massive excavation by a dredger resulted in a successful opening of the cave entrance, confirming both its geophysically determined location and its estimated depth. The application of an advanced geophysical method was therefore proven successful in providing a solution to this specific case in karst exploration and an important cave was saved.ground penetrating radar, speleology, cavity detection, Mt. Kanin massif, S-19 Cave

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Enhancing understanding of breakdown and collapse in the Yorkshire Dales using ground penetrating radar on cave sediments

Cited by 12 publications

References 6 publications

Stability of shallow karstic caverns in blocky rock masses

Stability of shallow karstic caverns in blocky rock masses

Multi‐offset ground penetrating radar methods to image buried foundations of a medieval town wall, Great Yarmouth, UK

Search for an artificially buried karst cave entrance using ground penetrating radar: a successful case of locating the S-19 Cave in the Mt. Kanin massif (NW Slovenia)

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