Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques

Cassidy, Nigel J.; Eddies, R.; Dods, S. D.

doi:10.1016/j.jappgeo.2011.06.003

Cited by 91 publications

(32 citation statements)

References 21 publications

(24 reference statements)

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“…Acoustic Imaging (sound and ultrasound waves) can be used at similar scales to x-ray imaging, and has the advantage of not needing a potentially hazardous source behind any surface to be investigated [33]. Imagery can be obtained over a larger area more rapidly than x-ray imaging, is typically good to centimetres and decimetres but requires careful…”

Section: Engineering Anthropology/archaeology Nondestructive Methodsmentioning

confidence: 99%

Search protocols for hidden forensic objects beneath floors and within walls

Ruffell¹,

Pringle²,

Forbes³

2014

Forensic Science International

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The burial of objects (human remains, explosives, weapons) below or behind concrete, brick, plaster or tiling may be associated with serious crime and are difficult locations to search. These are quite common forensic search scenarios but little has been published on them to-date. Most documented discoveries are accidental or from suspect/witness testimony. The problem in locating such hidden objects means a random, or chance-based approach is not advisable. A preliminary strategy is presented here, based on previous studies, augmented by primary research where new technology or applications are required. This blend allows a rudimentary search workflow, from remote desktop study, to non-destructive investigation through to recommendations as to how the above may inform excavation. Published case studies on the search for human remains demonstrate the problems encountered when trying to find and recover sealed-in and sealed-over locations. Established methods include desktop study, photography, geophysics and search dogs: these are integrated with new technology (LiDAR and laser scanning; photographic rectification; close-quarter aerial imagery; ground-penetrating radar on walls and gamma-ray/neutron activation radiography) to propose this possible search strategy.3

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Section: Engineering Anthropology/archaeology Nondestructive Methodsmentioning

confidence: 99%

Search protocols for hidden forensic objects beneath floors and within walls

Ruffell¹,

Pringle²,

Forbes³

2014

Forensic Science International

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“…An increase of the signal amplitude will be observed corresponding to the presence of cracks. Basing on this, it is possible to extract the spatial geometry of a crack from a GPR tomography …”

Section: Crack Inspectionmentioning

confidence: 99%

Comprehensive investigation of leakage problems for concrete gravity dams with penetrating cracks based on detection and monitoring data: A case study

2017

Struct Control Health Monit

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Summary The leakage amount is an important indicator evaluating the seepage behavior of a dam. Due to the complex behavior, crack development judgment and leakage behavior identification for concrete gravity dams remain a challenging task. The paper is concerned with comprehensive investigation of leakage problems for concrete gravity dams with penetrating cracks. A case study on Shimantan Reservoir Dam was taken to examine the utilization of the comprehensive investigation method. Deficiency investigations were undertaken to identify the nature and sources of defects responsible for the serious leakage. Based on the information acquired from field visual inspections and ground‐penetrating radar tests, it is apparent that several transverse cracks penetrate the dam crest and propagate downward into the dam body. The results of the remedial grouting, X‐ray diffraction analyses and water injection tests reflect the appearance of penetrating leakage paths in the dam body. Subsequently, 2 behavior models including the special hydrostatic‐seasonal‐time model and the inverse analysis model were conducted to distinguish the contribution of penetrating cracks to leakage amount. The special hydrostatic‐seasonal‐time model was modified to address the influence of leakage flow in real microcracks in concrete dams based on the Navier–Stokes equation. The result shows that the proposed models provide an acceptable accuracy in analyzing leakage monitoring data for gravity dams with penetrating cracks. Leakage flow in penetrating cracks plays a dominant role in the dam seepage field. The execution flow in this paper could be readily employed in investigations of similar problems of concrete dams.

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“…In our present research, this mechanism is used to study underground water leakages. GPR also allows efficient and high‐resolution assessment of hazards like subsurface voids and washouts (e.g., Cassidy, Eddies and Dods ; Lai, Chang and Sham ; Nobes ). This is because the physical contact between the sensors and the objects is not required in GPR, in contrast to some acoustic methods such as leak noise correlator or pipe cable detectors (Liu and Kleiner ).…”

Section: Introductionmentioning

confidence: 99%

“…GPR has been used on different pavement materials including asphalt, concrete pavements and block pavements in road networks in most densely populated cities (e.g., Loizos and Plati ; Cassidy et al . ; Shangguan et al . ; Yehia et al .…”

Section: Introductionmentioning

confidence: 99%

Field validation of water‐pipe leakage detection through spatial and time‐lapse analysis of GPR wave velocity

Cheung

Lai

2019

Near Surface Geophysics

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Detection of leakage in a buried water pipe is a crucial issue, as underground pipes become aged and these pipes are often used as pathways for aggressive chemical agents. Non‐destructive geophysical methods for identifying such underground leakages are of vital importance. Leakage detection in buried water pipes is sometimes carried out through specific acoustic methods. In this research, we have used ground‐penetrating radar as an alternative to such acoustic methods, because of the high sensitivity of electromagnetic waves to the presence of water in soil. This paper presents a methodology, illustrated by field‐scale ground‐penetrating radar experiments. Four water leakage points in a buried, ductile, iron, main‐water pipe were pre‐designed within a full‐scale (20 m long × 10 m wide) experimental set up. This facility was paved half by reinforced concrete and half by other pavement blocks. Four ground‐penetrating radar antennae with five nominal frequencies 200, 250, 400, 600 and 900 MHz were tested. Using a modified algorithm for common offset ground‐penetrating radar antennae, in this work, we measure the changes in electromagnetic wave velocity and wave reverberation, which sense upward and downward leakages, respectively. Leakages could be identified most clearly in the 600 MHz ground‐penetrating radar data. Our result suggests two potential applications in terms of detecting and defining the extent of multiple leakages in old water pipes, and testing and commissioning new pipes before and after pressurized tests.

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Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques

Cited by 91 publications

References 21 publications

Search protocols for hidden forensic objects beneath floors and within walls

Search protocols for hidden forensic objects beneath floors and within walls

Comprehensive investigation of leakage problems for concrete gravity dams with penetrating cracks based on detection and monitoring data: A case study

Field validation of water‐pipe leakage detection through spatial and time‐lapse analysis of GPR wave velocity

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