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GPR has emerged as one of the most relevant NDT technologies, which can be employed in various civil engineering (CE) applications. While the general applicability of GPR has been demonstrated, an objective evaluation of the limitations of GPR for qualitative inspection tasks is still missing. Therefore, the POD method, based on the “â vs. a” approach, was transferred to the application of GPR for...
Ballast material typically employed in rail track bed construction has been herein physically and electromagnetically characterized. Several ground-penetrating radar (GPR) tests have been carried out in a laboratory environment, wherein a proper set-up was realized. Four GPR systems comprising five different central frequencies of investigation have been used for the measurements. The impacts brought...
This paper studies the effects of relatively homogeneous (RHWD) and relatively inhomogeneous water distributions (RIWD) in soil compared by varying the water content through a wetting and drying cycle in a tank (1.85m long × 1.55m wide × 1m deep) filled with 750mm thick plant soil. During the cycle, a 900MHz antenna was regularly used to capture GPR radargrams on a buried steel pipe. Hyperbolic reflections...
We investigate the development of passive cooperative targets as sub-surface sensors interrogated by Ground Penetrating RADAR (GPR). Using piezoelectric substrates for converting the incoming electromagnetic pulse to an acoustic wave confined to the sensor surface (Surface Acoustic Wave transducer — SAW) allows for shrinking the sensor dimensions while providing sensing capability through the piezoelectric...
An ice road will be organized across bodies of water in winter to enable the movement of vehicles and people, thus creating the proper living and operating conditions for the local population and industry. Possible loads and measures necessary to ensure the rigidness of the ice must be considered when setting up such crossings. This article produces the results of research on the ice crossings using...
In the exploration and evaluation of the metalliferous veins, traditional geophysical inversion method can only get the indirect parameters of the target property, but cannot accurately reflect the geological parameters of ore veins media attributes. In order to get the intrinsic geological parameters and internal distribution of the metalliferous veins by means of inversion, in this paper, we construct...
In this paper, a vital sign feature (V SF) detection and search strategy using multiple UWB life-detection-radars with different locations is proposed. Firstly, the different VSFs from all single UWB life-detection radars placed on multiple radar observation points are categorized. Then, the proposed detection strategy is used for the different VSF categories. Finally, the target's spatial location...
Obtaining high quality and easy to interpret horizontal slices of the shallow subsurface depends on how a 3D ground penetrating radar (GPR) survey is acquired and processed. A field site containing three basic target geometries of linear pipes, curvilinear roots, and small objects serves as a testbed. High-density 250 and 500 MHz single channel GPR surveys covering 250m2 were acquired to evaluate...
This paper describes subsurface measurements using a singlehole directional borehole radar system that revealed the presence of a kind of guided wave propagating along the borehole. The radar system used dipole arrays for both the transmitter and receiver. In this case, all the antenna elements were located off the center axis of the borehole. Computer simulations confirmed that the off-center dipole...
This paper presents the results of an archaeological fieldwork project conducted by a pro-geophysics archaeologist (Atha) and two ‘archaeo-curious’ GPR specialists (Chang and Lai) at the San Tau backbeach site in Hong Kong. Previous small-scale test pitting suggested that the site might be a locally unique Tang dynasty cemetery, with probable later (Northern Song) activity, but grave definition was...
GPR has been used routinely in Saskatchewan, Canada, potash mines for nearly forty years. In general, the purpose of GPR surveys in potash mines is to map the salt-bed stratigraphy above and below the mined-out rooms. The stratigraphy in the Saskatoon, Saskatchewan area mines consists of a series of salt and potash beds separated by well-known and regionally distributed planar clay seams. The salt-beds...
We have developed 8Ch array GPR system “Yakumo” and have demonstrated the performance of the multistatic radar. At first, the effect of the antenna polarization and the antenna spacing to GPR signal in the multistatic GPR system was evaluated by a laboratory experiment. Using this multistatic GPR system, we can estimate the vertical profile of the electromagnetic wave velocity by CMP method at every...
GPR is a nondestructive detection method which has been widely applied to detect defects in concrete structures. In field geotechnical engineering cases, it is very hard to observe anomalies caused by longitudinal defects using ground-based GPR detection, which produces great difficulties in data processing and interpretation. Compared with the traditional ground-based GPR, the cross-hole GPR can...
Improving understanding of Arctic ecosystem functioning and parameterization of models that simulate freeze-thaw dynamics require advances in quantifying soil and snow properties. Due to the significant spatiotemporal variability of soil properties and the limited information provided by point-scale measurements (e.g., cores), geophysical methods hold potential for improving soil and permafrost characterization...
This paper describes experimental results carried out in skarn deposits with a polarization-sensitive directional borehole radar. This radar employs a dipole array and loop antenna in a borehole (DALAB), which was proposed in a previous study. This radar system was applied to polarimetric radar measurement of a fault and sphalerite veins in skarn. The fault may be regarded as a plane-type reflector...
Improving the safety of personnel and boosting productivity are fundamental drivers for the coal mining industry. Automated mining is seen as providing the ultimate outcome, with reliable sensing technology being a key enabler to this strategy. However present automation capability is being limited by a lack of sensing instrumentation that can reliably measure coal-strata geological structure. A related...
Provided that the frequency of the GPR antenna is properly selected, detecting rock fractures is generally an achievable task because most of the investigated rocks are resistive. On the other hand, fractures can be generally envisaged as thin-beds embedded in a homogenous rock formation, thus yielding a complex reflection pattern caused by the reverberation of the GPR signal back and forth within...
A high-efficiency scheme based on both time division multiplexing (TDM) and parallel processing of FPGA is proposed in this paper to address the problem of high scanning rate in high-speed measurements with UWB array GPR. The merit of this new scheme is that all trigger signals of all the channels can be delayed in a controllable step through the same delay chip at different times. Each channel of...
The NeTTUN (New Technologies for Tunnelling and Underground Works) Project involves a consortium of 23 industrial, research & development laboratories and small and medium enterprise organizations across 9 countries in Europe; the ultimate goal is to enable groundbreaking change in the construction and maintenance of tunnels. Most existing ground prediction methods require the stopping of excavation...
The use of tack coats in the construction of road structures is a technique that ensures pavement layer bonding. Unfortunately, existing techniques commonly used in France to study tack coats require coring of structures for a punctual characterization in a laboratory. This paper presents an innovative non-destructive approach to characterize the change of geometric and dielectric properties of the...
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