Automated Discontinuity Extraction Software Versus Manual Virtual Discontinuity Mapping: Performance Evaluation in Rock Mass Characterization and Rockfall Hazard Identification

Abstract. The use of remote sensing techniques is now common practice in different working environments, including engineering geology. Moreover, in recent years the development of structure from motion (SfM) methods, together with rapid technological improvement, has allowed the widespread use of cost effective remotely piloted aircraft systems (RPAS) for acquiring detailed and accurate geometrical information even in evolving environments, such as mining contexts. Indeed, the acquisition of remotely sensed data from hazardous areas provides accurate 3D models and high resolution orthophotos minimizing the risk for operators. The quality and quantity of the data obtainable from RPAS surveys can then be used for inspection of mining areas, audit of mining design, rock mass characterizations, stability analysis investigations and monitoring activities. Despite the widespread use of RPAS, its potential and limitations have still to be fully understood. In this paper a case study is shown where a RPAS was used for the engineering geological investigation of a closed marble mine area in Italy: direct ground based techniques couldn't be applied for safety reasons. In view of re-activation of the mining operations, high resolution images taken from different positions and heights were acquired and processed by using SfM techniques, for obtaining an accurate and detailed three-dimensional model of the area. The geometrical and radiometrical information was subsequently used for a deterministic rock mass characterization that led to the identification of two large marble blocks that pose a potential significant hazard issue for the future workforce. A preliminary stability analysis was then carried out in order to demonstrate the potential use of RPAS information in engineering geological contexts for geo-hazard identification, awareness and reduction.

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A digital face mapping case study in an underground hard rock mine

Canadian Geotechnical Journal ◽

10.1139/t04-046 ◽

2004 ◽

Vol 41 (6) ◽

pp. 1011-1025 ◽

Cited By ~ 2

Author(s):

Frank Lemy ◽

John Hadjigeorgiou

Keyword(s):

Neural Networks ◽

Rock Mass ◽

Hard Rock ◽

Rock Mass Characterization ◽

Exposed Rock ◽

Mapping System ◽

Discontinuity Mapping ◽

Structural Regime ◽

Trace Maps

This paper presents a case study of a digital discontinuity mapping system used as a rock mass characterization tool in an underground hard rock mine. This mapping system allows for a fast acquisition of information that can best characterize the geological structural regime without exposing workers to potentially unsafe conditions. This method can be used to overcome some of the shortcomings of traditional mapping methods, such as limited access to rock exposures. Photographic images of the exposed rock mass are introduced into a software package that has been developed to extract potential discontinuity traces using detection algorithms. Detected features that do not describe discontinuity traces are removed from the images using artificial neural networks. Operator intervention can improve the reliability of the system by linking incomplete discontinuity segments. This developed process results in the construction of a discontinuity trace map that can be used for rock mass characterization purposes. The system was employed to construct discontinuity trace maps of twenty 1.8 m by 1.8 m mapping windows from two locations in an underground hard rock mine. The ability of the system to quantify the geomechanical characteristics of the rock mass was evaluated by comparing the results with those of manually drawn discontinuity trace maps. The results of this study have helped to evaluate the digital face mapping system and identify its limitations.Key words: rock mass characterization, image processing, discontinuity networks, neural networks.

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Rock Mass Characterization of Karstified Marbles and Evaluation of Rockfall Potential Based on Traditional and SfM-Based Methods; Case Study of Nestos, Greece

Geosciences ◽

10.3390/geosciences10100389 ◽

2020 ◽

Vol 10 (10) ◽

pp. 389

Author(s):

George Papathanassiou ◽

Adrián Riquelme ◽

Theofilos Tzevelekis ◽

Evaggelos Evaggelou

Keyword(s):

Rock Mass ◽

New Technologies ◽

Runout Distance ◽

Rockfall Hazard ◽

Rock Mass Characterization ◽

Railway Line ◽

Aircraft Systems ◽

Remotely Piloted Aircraft

Rockfall consists one of the most harmful geological phenomena for the man-made environment. In order to evaluate the rockfall hazard, a variety of engineering geological studies should be realized, starting from conducting a detailed field survey and ending with simulating the trajectory of likely to fail blocks in order to evaluate the kinetic energy and the runout distance. The last decade, new technologies, i.e., remotely piloted aircraft systems (RPAS) and light detection and ranging (LiDAR) are frequently used in order to obtain and analyze the characteristics of the rock mass based on a semi-automatic or manual approach. Aiming to evaluate the rockfall hazard in the area of Nestos, Greece, we applied both traditional and structure from motion (SfM)-oriented approaches and compared the results. As an outcome, it was shown that the semi-automated approaches can accurately detect the discontinuities and define their orientation, and thus can be used in inaccessible areas. Considering the rockfall risk, it was shown that the railway line in the study area is threaten by a rockfall and consequently the construction of a rockfall netting mesh or a rock shed is recommended.

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Fracture System and Rock-Mass Characterization by Borehole Camera Surveying: Application in Dimension Stone Investigations in Geologically Complex Structures

Applied Sciences ◽

10.3390/app11020764 ◽

2021 ◽

Vol 11 (2) ◽

pp. 764

Author(s):

Ivica Pavičić ◽

Ivo Galić ◽

Mišo Kucelj ◽

Ivan Dragičević

Keyword(s):

Rock Mass ◽

Fractured Rock ◽

Low Cost ◽

Fracture Pattern ◽

Dimension Stone ◽

Rock Mass Characterization ◽

Size And Shape ◽

Distribution Parameters ◽

Borehole Camera ◽

Fracture Distribution

The successful exploration of dimension stone mainly depends on the quality, size, and shape of extractable blocks of dimension stone. The investigated area is in the Pelješac Peninsula (Croatia), in the External Dinarides orogeny, built from thick carbonate succession, characterized by relatively small deposits of high-quality dimension stone. These conditions demand challenging geological investigations in the “pre-quarry” phase to find optimal quarry location. The size and shape of dimension stone blocks are mainly controlled by fracture pattern systems. In the rugged, covered terrains, it is very hard to obtain a satisfactory amount of fracture data from the surface, so it is necessary to collect them from the underground. Borehole camera technology can visualize the inner part of the rock mass and measure the fracture characteristics. The main conclusions are as follows: (1) the digital borehole camera technology provides a quick, effective, and low-cost geological survey of fractured rock mass; (2) statistical fracture distribution parameters, P10, fracture spacing, Volumetric Joint Count (Jv) based on borehole wall survey can reflect the integrity of rock mass, providing a solid decision-making base for further investment plans and dimension stone excavation method.

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