scholarly journals Analysis of Small-Loop Electromagnetic Signals to Detect Subsurface Anomaly Zones

2020 ◽  
Vol 10 (18) ◽  
pp. 6329
Author(s):  
Dong-Hyuk Kim ◽  
Ki-Hyo Choi ◽  
Chan-Hee Lee ◽  
Jin-Hoon Jeong
Keyword(s):  
Electrical Resistivity ◽  
Urban Areas ◽  
Superposition Method ◽  
Contour Map ◽  
Road Pavement ◽  
Relative Standard ◽  
Small Loop ◽  
Box Plot ◽  
Electromagnetic Signals ◽  
Subsurface Cavities

Recently, sinkholes have significantly increased in urban areas as a result of subsurface cavities and ground softening. In this study, a small-loop electromagnetic survey was conducted in a testbed where anomaly zones comprised of cavities, areas of ground softening, and underground facilities were simulated in the ground under road pavement using the CMD Mini Explorer. The equipment was only able to measure the electrical resistivity (ER) at three depths. As, occasionally, the equipment was unable to detect the anomaly zones using the ER measured at those three depths, survey measurements were taken at three heights to collect the ER at seven depths using the superposition method. The result shows that the anomaly zones can be detected qualitatively by visually observing the contour map of the ER. In addition, another method for detecting anomaly zones in the ground statistically using a box plot and the relative standard deviation was employed in this study. Consequently, the position and depth of the cavities, areas of ground softening, and underground facilities in the testbed can also be determined quantitatively.

An evaluation of Bristow’s method for the detection of subsurface cavities

Geophysics ◽  
1990 ◽  
Vol 55 (5) ◽  
pp. 514-520 ◽  
Author(s):  
Tony Lowry ◽  
Peter N. Shive
Keyword(s):  
Electrical Resistivity ◽  
Graphical Method ◽  
Effective Means ◽  
Slight Variation ◽  
Electrode Arrays ◽  
Cavity Detection ◽  
Field Investigations ◽  
Spherical Cavities ◽  
Cylindrical Cavities ◽  
Subsurface Cavities

The Bristow method, an electrical resistivity technique employing a pole‐dipole measurement array in conjunction with a simple graphical method of interpretation, has proven an effective means of locating subsurface cavities. There have been questions, however, regarding the limits of the method and whether the Bristow method is indeed the most suitable of the various electrical resistivity techniques for cavity detection. In hopes of resolving some of the controversy surrounding Bristow’s method, resistivity traverses are numerically modeled over spherical and cylindrical cavities given a variety of circumstances. Using a slight variation of Bristow’s original interpretive technique on modeled data, the size and location of subsurface cavities can be determined with surprising accuracy. However, when the simulation is altered to incorporate geologic noise, the maximum depth at which a cavity can be detected is found to be far less than has been reported in field investigations. In this instance the presence of a cylindrical cavity cannot be discerned beyond a depth to the top approximately equal to the diameter of the cavity, and spherical cavities are indistinguishable at depths much greater than the radius. One should note that the noise field generated for this model may not be representative of what would normally be found in the real earth. In the field, the maximum achievable depth of detection will vary depending on the actual geologic conditions and whether some technique is employed to reduce the effects of noise. In any case, a comparison of traverses using various electrode arrays confirms that the Bristow method is the most satisfactory of the applicable electrical resistivity techniques.

scholarly journals Time-Lapse Electrical Resistivity Investigations for Imaging the Grouting Injection in Shallow Subsurface Cavities

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Muhammad Farooq ◽  
Samgyu Park ◽  
Jung Ho Kim ◽  
Young Soo Song ◽  
Mohammad Amjad Sabir ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Research Work ◽  
Geophysical Methods ◽  
Ground Surface ◽  
Mineral Resources ◽  
Direct Methods ◽  
Time Lapse ◽  
Mechanical Resistance ◽  
Borehole Camera ◽  
Subsurface Cavities

The highway of Yongweol-ri, Muan-gun, south-western part of the South Korean Peninsula, is underlain by the abandoned of subsurface cavities, which were discovered in 2005. These cavities lie at shallow depths with the range of 5∼15 meters below the ground surface. Numerous subsidence events have repeatedly occurred in the past few years, damaging infrastructure and highway. As a result of continuing subsidence issues, the Korean Institute of Geosciences and Mineral Resources (KIGAM) was requested by local administration to resolve the issue. The KIGAM used geophysical methods to delineate subsurface cavities and improve more refined understanding of the cavities network in the study area. Cement based grouting has been widely employed in the construction industry to reinforce subsurface ground. In this research work, time-lapse electrical resistivity surveys were accomplished to monitor the grouting injection in the subsurface cavities beneath the highway, which have provided a quasi-real-time monitoring for modifying the subsurface cavities related to ground reinforcement, which would be difficult with direct methods. The results obtained from time-lapse electrical resistivity technique have satisfactory imaged the grouting injection experiment in the subsurface cavities beneath the highway. Furthermore, the borehole camera confirmed the presence of grouting material in the subsurface cavities, and hence this procedure increases the mechanical resistance of subsurface cavities below the highway.

Application of Electrical Resistivity Method to Evaluate the Extent of Mortar Infiltration in Subsurface Cavities

2012 ◽  
Vol 38 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Muhammad Farooq ◽  
Samgyu Park ◽  
Young Soo Song ◽  
Jung Ho Kim ◽  
Muhammad Amjad Sabir ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Resistivity Method ◽  
Electrical Resistivity Method ◽  
Subsurface Cavities

Efficient extraction of road information for car navigation applications using road pavement markings obtained from aerial images

2006 ◽  
Vol 33 (10) ◽  
pp. 1320-1331 ◽  
Author(s):  
Jin Gon Kim ◽  
Dong Yeob Han ◽  
Ki Yun Yu ◽  
Yong Il Kim ◽  
Sung Mo Rhee
Keyword(s):  
Urban Areas ◽  
Template Matching ◽  
Location Based Services ◽  
Aerial Images ◽  
Aerial Image ◽  
Ground Truth Data ◽  
Pavement Markings ◽  
Road Pavement ◽  
Efficient Extraction ◽  
Car Navigation

The efficient extraction of road information is increasingly important with the rapid growth of road-related services, such as car navigation systems, telematics, and location-based services. Conventional methods of creating and updating road information are expensive and time consuming. Therefore, a set of processes is required that collects the same information more efficiently. We propose a new method for collecting road information in complex urban areas from road pavement markings located on aerial images. This information includes lane and symbol markings that guide direction; the geometric properties of the pavement markings and their spatial relationships are analyzed. Road construction manuals and a series of cutting-edge techniques, including template matching, are used in our analysis. To validate our approach, the accuracy of our results was evaluated by comparing the data with manually extracted ground truth data. Our approach demonstrates that road information can be extracted efficiently to an extent in a complex urban area.Key words: aerial image, automatic extraction, pavement marking, road information, CNS.

scholarly journals Prospecting for voids with vertical radar profiling

2001 ◽  
Vol 34 (4) ◽  
pp. 1363
Author(s):  
I. F. IOANNIS
Keyword(s):  
Electrical Resistivity ◽  
Seismic Tomography ◽  
Vertical Profile ◽  
Electrical Resistivity Survey ◽  
Resistivity Survey ◽  
Receiving Antenna ◽  
Subsurface Cavities ◽  
Archaeological Excavations

Vertical Radar Profiling measurements were conducted to image subsurface cavities encountered in Akrotiri Archaeological Excavations area on Thera Island. The vertical radar profiling technique is able to explore much deeper than conventional surface GPR because it uses wells. The transmitting-receiving antenna unit was moved within the excavated well along six vertical profile lines in equally divided positions. A local electrical resistivity survey preceded the GPR profiles to investigate if the conductivity of the pyroclastic formation satisfies the presuppositions to conduct GPR measurements. The vertical GPR profiles revealed locations where cavities exist but they were unable to show their shape and extent. Cross-well seismic tomography images supported the vertical radar profiling results.

scholarly journals Effect of Sampietrini Pavers on Urban Heat Islands

2021 ◽  
Vol 18 (24) ◽  
pp. 13108
Author(s):  
Laura Moretti ◽  
Giuseppe Cantisani ◽  
Marco Carpiceci ◽  
Antonio D’Andrea ◽  
Giulia Del Serrone ◽  
...  
Keyword(s):  
Air Temperature ◽  
Urban Areas ◽  
Lower Surface ◽  
Early Morning ◽  
Urban Heat Islands ◽  
Predicted Mean Vote ◽  
Heat Islands ◽  
The Road ◽  
Road Pavement ◽  
Microclimatic Conditions

Cool pavements are reflective and/or permeable pavements that improve microclimate of urban areas where heat islands cause discomfort to citizens. Stone pavements lower surface temperatures and reduce the amount of heat absorbed. This study assessed, using ENVI-met 4.3 LITE software, how air temperature and predicted mean vote depend on physical properties of the road pavement. A comparative microclimatic analysis was implemented on a rectangular square in Rome (Italy) in the summer, paved in three different ways: asphalt, traditional sampietrini, and permeable sampietrini. The model considered local weather parameters, surrounding fabric, and vegetation to give reliable results in terms of numerical and graphical output using the application tool Leonardo. The tested pavement types affected air temperature during the day, but did not influence this variable in the early morning. Permeable sampietrini pavement was more effective than traditional sampietrini pavement in reducing air temperature compared to the current asphalt surface. The road pavement did not, however, affect human comfort in terms of predicted mean vote. The obtained results are useful for further investigation of parameters that could modify the microclimatic conditions of urban areas.

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