scholarly journals Multiconfiguration GPR measurements for geometric fracture characterization in limestone cliffs (Alps)

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. B85-B92 ◽  
Author(s):  
Mathieu Jeannin ◽  
Stéphane Garambois ◽  
Colette Grégoire ◽  
Denis Jongmans
Keyword(s):  
Rock Mass ◽  
Test Site ◽  
Fracture Characterization ◽  
Rock Stability ◽  
Transmission Data ◽  
Velocity Image ◽  
Maximum Penetration ◽  
Rock Mass Fracturing ◽  
Ground Penetrating

Rock-mass fracturing is a key parameter in rock-fall hazard assessment. However, traditional geologic observations can provide information only about discontinuities at the surface. In this case study, detailed ground-penetrating-radar (GPR) measurements (with antennas of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) were conducted on a test site, using different acquisition configurations deployed on vertical cliff faces. Conventional 2D profile data, common-midpoint (CMP) survey data, and transmission data were acquired to evaluate the potential use of radar waves to characterize the geometry and properties of the major discontinuities (fractures) within a Mesozoic limestone massif. Results showed that the continuity and geometry (orientation and dip) of the major observed fractures, which are crucial parameters for assessing rock stability, can be obtained by combining vertical and horizontal profiles measured along the cliff. We used [Formula: see text] antennae and reached a maximum penetration of [Formula: see text], which limits the technique to rock volumes of a few tens of thousands of cubic meters. We observed significant differences in reflectivity along the detected fractures, which suggests that the fractures’ characteristics vary in the rock mass. We used transmission data to obtain a radar velocity image. Although the results were consistent with radar profiles on the cliff, they showed that the technique has little utility, beyond that of more traditional GPR methods, for delineating fractures in a rock mass.

scholarly journals Ground Penetrating Radar as a Functional Tool to Outline the Presence of Buried Waste: A Case Study in South Italy

2021 ◽  
Vol 13 (7) ◽  
pp. 3805
Author(s):  
Carmine Massarelli ◽  
Claudia Campanale ◽  
Vito Felice Uricchio
Keyword(s):  
Ground Penetrating Radar ◽  
Test Site ◽  
Control Area ◽  
Natural Soil ◽  
Electrically Conductive ◽  
Bituminous Mixtures ◽  
South Italy ◽  
Survey System ◽  
Ground Penetrating

The ability of the ground penetrating radar (GPR) method as a rapid preliminary survey to detect the presence of illegally buried waste is presented in this paper. The test site is located in the countryside of “Sannicandro di Bari” (Southern Italy) and has a surface area of 1500 m2. A total of five parallel profiles were acquired in 2014 using a geophysical survey system instrument (GSSI) equipped with 400 and 200 MHz antennae in the monostatic configuration. Two of the five profiles were registered in a control area to compare a natural condition to a suspected waste buried zone. As a result of a processing and elaboration workflow, GPR investigations allowed us to interpret the signal qualitatively within a maximum depth of about 3 m, identifying many signal anomalies, whose characteristics can be considered typical of buried waste. The GPR response of the three profiles acquired in the suspected area showed substantial differences not found in the control’s profiles. Anomalies related to the presence of intense scattering, of dome structures not attributable to cavities, but rather to a flattening and compacting of different layers, therefore, less electrically conductive, were identified in the suspected area. The interpretation of the results obtained by the GPR profiles was confirmed by excavations carried out with bulldozers. Large quantities of solid waste illegally buried (e.g., waste deriving from construction and demolition activities, bituminous mixtures, discarded tires, glass, plastic, municipal waste) were revealed in all the sites where anomalies and non-conformities appeared compared to the control natural soil.

scholarly journals Monitoring Lakes Surface Water Velocity with SAR: A Feasibility Study on Lake Garda, Italy

2021 ◽  
Vol 13 (12) ◽  
pp. 2293
Author(s):  
Marina Amadori ◽  
Virginia Zamparelli ◽  
Giacomo De Carolis ◽  
Gianfranco Fornaro ◽  
Marco Toffolon ◽  
...  
Keyword(s):  
Surface Water ◽  
Wind Waves ◽  
Test Site ◽  
Water Velocity ◽  
Surface Velocity ◽  
Medium Size ◽  
Small Scale ◽  
Lake Garda ◽  
Marine Applications

The SAR Doppler frequencies are directly related to the motion of the scatterers in the illuminated area and have already been used in marine applications to monitor moving water surfaces. Here we investigate the possibility of retrieving surface water velocity from SAR Doppler analysis in medium-size lakes. ENVISAT images of the test site (Lake Garda) are processed and the Doppler Centroid Anomaly technique is adopted. The resulting surface velocity maps are compared with the outputs of a hydrodynamic model specifically validated for the case study. Thermal images from MODIS Terra are used in support of the modeling results. The surface velocity retrieved from SAR is found to overestimate the numerical results and the existence of a bias is investigated. In marine applications, such bias is traditionally removed through Geophysical Model Functions (GMFs) by ascribing it to a fully developed wind waves spectrum. We found that such an assumption is not supported in our case study, due to the small-scale variations of topography and wind. The role of wind intensity and duration on the results from SAR is evaluated, and the inclusion of lake bathymetry and the SAR backscatter gradient is recommended for the future development of GMFs suitable for lake environments.

scholarly journals Mapping Complex Land Use Histories and Urban Renewal Using Ground Penetrating Radar: A Case Study from Fort Stanwix

2021 ◽  
Vol 13 (13) ◽  
pp. 2478
Author(s):  
Tyler Stumpf ◽  
Daniel P. Bigman ◽  
Dominic J. Day
Keyword(s):  
Urban Expansion ◽  
Educational Programming ◽  
Additional Information ◽  
National Monument ◽  
Early Colonial ◽  
Historic Structures ◽  
Economic Revitalization ◽  
Management Plans ◽  
Ground Penetrating

Fort Stanwix National Monument, located in Rome, NY, is a historic park with a complex use history dating back to the early Colonial period and through the urban expansion and recent economic revitalization of the City of Rome. The goal of this study was to conduct a GPR investigation over an area approximately 1 acre in size to identify buried historic features (particularly buildings) so park management can preserve these resources and develop appropriate educational programming and management plans. The GPR recorded reflection events consistent with our expectations of historic structures. Differences in size, shape, orientation, and depth suggest that these responses likely date to different time periods in the site’s history. The GPR recorded other reflection anomalies that are difficult to interpret without any additional information, which suggests that pairing high-density geophysical data with limited excavations is critical to elaborate a complex site’s intricate history.

Application of ABAQUS in Surrounding Rock Stability Analysis of Shallow Large Cross-Section Tunnel

2015 ◽  
Vol 777 ◽  
pp. 8-12 ◽  
Author(s):  
Lin Zhen Cai ◽  
Cheng Liang Zhang
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Strong Support ◽  
Surrounding Rock ◽  
Tunnel Engineering ◽  
Tunnel Excavation ◽  
Rock Stability ◽  
Rock Bolting ◽  
Excavation Support ◽  
The Stability

HuJiaDi tunnel construction of Dai Gong highway is troublesome, the surrounding-rock mass give priority to full to strong weathering basalt, surrounding rock integrity is poor, weak self-stability of surrounding rock, and tunnel is prone to collapse. In order to reduce disturbance, taking advantage of the ability of rock mass, excavation adopt the method of "more steps, short footage and strong support". The excavation method using three steps excavation, The excavation footage is about 1.2 ~ 1.5 m; The surrounding rock bolting system still produce a large deformation after completion of the first support construction, it shows that the adopted support intensity cannot guarantee the stability of the tunnel engineering. Using ABAQUS to simulate tunnel excavation support, optimizing the support parameters of the tunnel, conducting comparative analysis with Monitoring and Measuring and numerical simulation results, it shows that the displacement - time curves have a certain consistency in numerical simulation of ABAQUS and Monitoring and Measuring.

Implementation of InfraRed Thermographic surveys in complex coastal areas: the case study of Polignano a Mare (southern Italy)

2021 ◽  
Author(s):  
Lidia Loiotine ◽  
Marco La Salandra ◽  
Gioacchino Francesco Andriani ◽  
Eliana Apicella ◽  
Michel Jaboyedoff ◽  
...  
Keyword(s):  
Rock Mass ◽  
Structure From Motion ◽  
Southern Italy ◽  
Thermal Imager ◽  
Rock Masses ◽  
Field Surveys ◽  
Thermal Images ◽  
Thermal Anomalies ◽  
Rock Face

<p><em>InfraRed Thermography</em> (IRT) spread quickly during the second half of the 20<sup>th</sup> century in the military, industrial and medical fields. This technique is at present widely used in the building sector to detect structural defects and energy losses. Being a non-destructive diagnostic technique, IRT was also introduced in the Earth Sciences, especially in the volcanology and environmental fields, yet its application for geostructural surveys is of recent development. Indeed, the acquisition of thermal images on rock masses could be an efficient tool for identifying fractures and voids, thus detecting signs of potential failures.<br>Further tests of thermal cameras on rock masses could help to evaluate the applicability, advantages and limits of the IRT technology for characterizing rock masses in different geological settings.<br>We present some results of IRT surveys carried out in the coastal area of Polignano a Mare (southern Italy), and their correlation with other remote sensing techniques (i.e. <em>Terrestrial Laser Scanning</em> and <em>Structure from Motion</em>). The case study (<em>Lama Monachile</em>) is represented by a 20 m-high cliff made up of Plio-Pleistocene calcarenites overlying Cretaceous limestones. Conjugate fracture systems, karst features, folds and faults, were detected in the rock mass during field surveys. In addition, dense vegetation and anthropogenic elements, which at places modified the natural setting of the rock mass, represent relevant disturbances for the characterization of the rock mass. In this context, IRT surveys were added to the other techniques, aimed at detecting the major discontinuities and fractured zones, based on potential thermal anomalies. <br>IRT surveys were carried out in December 2020 on the east side of the rock mass at <em>Lama Monachile</em> site. Thermal images were acquired every 20 minutes for 24 hours by means of a FLIR T-660 thermal imager mounted on a fixed tripod. Ambient air temperature and relative humidity were measured during the acquisition with a pocketsize thermo-hydrometer. A reflective paper was placed at the base of the cliff to measure the reflected apparent temperature. In addition, three thermocouple sensors were fixed to the different lithologic units of the rock face. These parameters, together with the distance between the FLIR T-660 and the rock face, were used in order to calibrate the thermal imager and correct the apparent temperatures recorded by the device, during the post-processing phase. Successively, vertical profiles showing the temperature of the rock face over time were extracted from the thermograms. Thermal anomalies were correlated with stratigraphic and Geological Strength Index profiles, obtained by means of field surveys and Structure from Motion techniques. The presence of fracture and voids in the rock mass was also investigated.</p>

Assessment of destressing drilling efficiency using numerical methods: A case-study of Oktyabrsky deposit

2021 ◽  
pp. 26-31
Author(s):  
M. P. Sergunin ◽  
T. P. Darbinyan ◽  
T. S. Mushtekenov ◽  
V. V. Balandin
Keyword(s):  
Rock Mass ◽  
Theoretical Research ◽  
Labor Input ◽  
Efficiency Criterion ◽  
Strength And Deformation ◽  
Low Efficiency ◽  
Full Scale Tests ◽  
Time Required ◽  
Polar Division

Mineral mining in rockburst-hazardous conditions should involve various precautions in compliance with federal regulations and standards. One of the main methods to prevent rock bursts is destressing drilling. In this method, a yielding zone is artificially created. The strength and deformation characteristics in this zone differ from the same characteristics of enclosing rock mass, and redistribution of stresses takes place as a result. Efficiency of destressing drilling is estimated in terms of ore body S-2 in Komsomolsky Mine. The efficiency criterion is selected to be the safety factor of rock mass with and without destressing drilling. Low efficiency of destressing drilling means that this method is readily replaceable by the other techniques of lesser labor input, for example, by reduction in the rate of mining, or by seasoning of underground excavations for some time required for redistribution of stresses to take place. Based on the theoretical research and the conclusions drawn at NorNickel’s Polar Division, the full-scale tests are scheduled for the implementation in order to gradually abandon destessing drilling in rockburst-hazardous Talnakh and Oktyabrsky ore fields. The authors appreciate participation of V. P. Marysyuk from NorNickel’s Polar Division in this study.

scholarly journals Geophysical identification of voids and loosened zones in the shallow subsurface of post-mining areas

2018 ◽  
Vol 66 ◽  
pp. 01001 ◽  
Author(s):  
Zenon Pilecki
Keyword(s):  
Rock Mass ◽  
Geophysical Methods ◽  
Ore Deposits ◽  
Hard Coal ◽  
Shallow Subsurface ◽  
Mining Areas ◽  
Upper Silesian Coal Basin ◽  
Discontinuous Deformation ◽  
Ground Penetrating ◽  
Terrain Surface

The shallow historic exploitation of Zn-Pb/Fe ore deposits as well as hard coal has generated many discontinuous deformations on the terrain surface in the Upper Silesian Coal Basin/Poland. Discontinuous deformations occur in different forms as sinkholes, synclines, cracks, faults or ditches. The basic cause of their occurrence is the presence of void and loosened zones in the shallow subsurface. If the appropriate conditions arise, the sinkhole process begins to move upwards and may cause a discontinuous deformation on the terrain surface. Typically, geophysical methods are used for void and loosened zone identification. The most effective methods are gravimetric, seismic, electric resistivity and ground penetrating radar (GPR). Geophysical testing, requires distinct changes in the physical properties in the rock mass. The identified geophysical anomalies should be verified by control borehole and borehole tests to confirm the presence of the void and loosened zones in the rock mass. The results of control drilling and borehole tests determine the need to apply treatment works. In order to assess the threat of the occurrence of discontinuous deformations in the areas of historical shallow mining in Upper Silesia, a classification system based on geophysical tests has also been developed.

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