A review of laser scanning for geological and geotechnical applications in underground mining

Laser scanning can provide timely assessments of mine sites despite adverse challenges in the operational environment. Although there are several published articles on laser scanning, there is a need to review them in the context of underground mining applications. To this end, a holistic review of laser scanning is presented including progress in 3D scanning systems, data capture/processing techniques and primary applications in underground mines. Laser scanning technology has advanced significantly in terms of mobility and mapping, but there are constraints in coherent and consistent data collection at certain mines due to feature deficiency, dynamics, and environmental influences such as dust and water. Studies suggest that laser scanning has matured over the years for change detection, clearance measurements and structure mapping applications. However, there is scope for improvements in lithology identification, surface parameter measurements, logistic tracking and autonomous navigation. Laser scanning has the potential to provide real-time solutions but the lack of infrastructure in underground mines for data transfer, geodetic networking and processing capacity remain limiting factors. Nevertheless, laser scanners are becoming an integral part of mine automation thanks to their affordability, accuracy and mobility, which should support their widespread usage in years to come

Fracture mapping in challenging environment: a 3D virtual reality approach combining terrestrial LiDAR and high definition images

ArticleThis is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.The latest technological developments in computer vision allow the creation of georeferenced, non-immersive desktop virtual reality (VR) environments. VR uses a computer to produce a simulated three-dimensional world in which it is possible to interact with objects and derive metric and thematic data. In this context, modern geomatic tools enable the remote acquisition of information that can be used to produce georeferenced high-definition 3D models: these can be used to create a VR in support of rock mass data processing, analysis, and interpretation. Data from laser scanning and high quality images were combined to map deterministically and characterise discontinuities with the aim of creating accurate rock mass models. Discontinuities were compared with data from traditional engineering-geological surveys in order to check the level of accuracy in terms of the attitude of individual joints and sets. The quality of data collected through geomatic surveys and field measurements in two marble quarries of the Apuan Alps (Italy) was very satisfactory. Some fundamental geotechnical indices (e.g. joint roughness, alteration, opening, moisture, and infill) were also included in the VR models. Data were grouped, analysed, and shared in a single repository for VR visualization and stability analysis in order to study the interaction between geology and human activities.The authors gratefully acknowledge the assistance of the personal of the Romana Quarry and particularly Corniani M. This paper was possible because of support from the Tuscany Region Research Project known as “Health and safety in the quarries of ornamental stones—SECURECAVE”. The authors acknowledge Pellegri M and Gullì D (Local Sanitary Agency n.1, Mining Engineering Operative Unit—Department of Prevention) and Riccucci S (Centre of GeoTechnologies, University of Siena) for their support of this research

Terrestrial Remote Sensing techniques to complement conventional geomechanical surveys for the assessment of landslide hazard: The San Leo case study (Italy)

The San Leo village, located near to Rimini (northern Italy), was built in the medieval period on the top of a calcarenite and sandstone plateau, affected by lateral spreading associated with secondary rock falls and topples. In fact, a number of landslides endangered the historical town since centuries. In order to describe the structural features driving these slope instability phenomena, a complete Terrestrial Laser Scanner (TLS) survey all around the San Leo cliff was performed. Moreover, Close-Range Photogrammetric (CRP) surveys and conventional geomechanical surveys on scanlines have been carried out. The 3D geometry of the cliffs was extracted and critical areas have been investigated in detail using dense Digital Surface Models (DSMs) obtained from CRP or TLS. The results were used to define the structural features of the plateau, to recognize more fractured areas, and to perform kinematic analyses, in order to assess the joint sets predisposing to slope instability at the cliff scale. The creation of a 3D model was also fundamental for the implementation of the geological model to be used in numerical modelling for hydrogeological characterization and slope stability analyses

A case study integrating remote sensing and distinct element analysis to quarry slope stability assessment in the Monte Altissimo area, Italy

This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.enggeo.2014.09.003. First available online 22 September 2014Over last decade geomatic techniques have been increasingly used for the geometrical characterization of rock slopes. Terrestrial laser scanning and digital terrestrial photogrammetry in particular are now frequently used in the characterization of joint surfaces and slope geometry. Although the use of these techniques for the structural characterization of slopes is widely documented, limited research has been undertaken to improve our understanding of the importance of the derived data quality in the construction of slope geometry imported into 3D numerical models. One of the most common problems encountered in the use of these techniques, especially in case of slopes with complex geometry, is the presence of occlusions. In this context, the aims of this paper are to describe how the integrated use of terrestrial laser scanning, digital terrestrial photogrammetry and topographic surveys can mitigate the influence of occlusions and how the slope geometry gained from these surveys can be important in slope stability analyses. For this purpose a case study in the Monte Altissimo area (Apuan Alps, Italy) will be presented. Several geomatic techniques were used for studying a slope overhanging the Granolesa quarry. Special emphasis will be given to the importance of using Total Station and Differential GPS surveys as tools for data fusion. Moreover, in order to validate this procedure, the accuracy and precision of the output were determined through comparison of 3D models derived from laser scanning and digital terrestrial photogrammetry.Furthermore, two different analyses with the three-dimensional distinct element code, 3DEC, were carried out in order to highlight the advantages and limitations of using data obtained from terrestrial remote sensing techniques as opposed to models based on topographic maps.The authors wish to thank the Tuscany Region which funded this research (Announcement 6744/2008 POR CREO 2007–2013). Moreover, we are extremely grateful to Henraux S.p.A., Prof. Pier Lorenzo Fantozzi (University of Siena), Geol. Sergio Mancini, Geol. Vinicio Lorenzoni and Ing. Matteo Lapini (Ingeo Systems s.r.l.) for their assistance and advices in this research

Comparison of remote sensing techniques for geostructural analysis and cliff monitoring in coastal areas of high tourist attraction: the case study of Polignano a Mare (Southern Italy)

Rock slope failures in urban areas may represent a serious hazard for human life, as well as private and public property, even on the occasion of sporadic episodes. Prevention and mitigation measures indispensably require a proper rock mass characterization, which is often achieved by means of time-consuming, costly and dangerous field surveys. In the last decades, remote sensing devices such as high-resolution digital cameras, laser scanners and drones have been widely used as supplementary techniques for rock slope analysis and monitoring, especially in poorly accessible areas, or in sites of large extension. Although several methods for rock mass characterization by means of remote sensing techniques have been reported in specific studies, there are very few contributions that focused on comparing the different methods in an attempt to establish their advantages and limitations. With this study, we performed digital photogrammetry, Terrestrial Laser Scanning and Unmanned Aerial Vehicle surveys on a cliff located in a popular tourist attraction site, characterized by complex geological and geomorphological settings, as well as by disturbance elements such as vegetation and human activities. For each point cloud, we applied geostructural analysis by means of semi-automatic methods, and then compared multi-temporal acquisitions for cliff monitoring. By quantitative comparison of the results and validation by means of conventional geostructural field surveys, the pros and cons of each method were outlined in attempt to depict the conditions and goals the different techniques seem to be more suitable fo

Control of natural fractures in historical quarries via 3D point cloud analysis

This paper applies remote sensing techniques and 3D point cloud (3DPC) analysis to the study of historical quarries and the relationship between old quarry landscapes and the natural fracture systems of rock massifs. Ancient quarry landscapes present particular characteristics and different features from those of modern quarries. Consequently, specific considerations are needed when historical extractive places are studied. The proposed method is based on terrestrial 3D laser scanners and the structure from motion technique with remotely piloted aircraft systems. Additional specific fieldwork is required to identify and characterise quarry faces from old, blurry outcrops. A case study of the 18th century “Rambla Honda” quarries in La Romana (Alicante, SE Spain) is presented. The comparison between the fieldwork and 3DPC analysis enables the numbers and orientations of both (1) the discontinuity sets within the rock mass facilitating extraction and (2) the planes resulting from block extraction (traditional quarry faces) to be determined. The comparative analysis reveals how the stonecutters managed the extraction. The results show that structural and stratigraphic discontinuities act as planes of weakness for block extraction and determine the optimum orientation of the quarry face for minimising efforts and rock waste. The final quarry landscape is formed from the superposition of natural and artificial surfaces, but currently they appear eroded and partially covered by silting and plants. The proposed methodology contributes to distinguishing both natural and artificial discontinuities and to achieving a comprehensive knowledge of these cultural places.This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and EU FEDER under Project TEC2017-85244-C2-1-P, the University of Alicante (Vigrob-157 and GRE18-15), and the Spanish Ministry of Science and Innovation (Grants PID2020-116896RB-C21 and PID2020-116896RB-C22 funded by MCIN/AEI/10.13039/501100011033)

Terrestrial laser scanning for rockfall stability analysis in the cultural heritage site of Pitigliano (Italy)

Traditional surveying methods are often not sufficient to achieve a complete geomechanical characterization of the rock mass, to analyze the instability mechanisms threatening the cultural heritage of hilltop historic towns. In Pitigliano (Tuscany, Central Italy), terrestrial laser scanning was employed complementarily to conventional geomechanical techniques. The overall 3D survey of the exposed surfaces was combined with scanlines of the inner walls of the subterranean cavities running underneath the historic centre. The rock mass discontinuities geometry was extracted, and the most critical instability mechanisms were mapped, with particular interest in the potential impacts on the ancient buildings located along the cliff edge. The geomechanical analysis of the surveyed joint sets confirmed a structural control on the cliff morphology by two main joint sets. Thanks to the laser scanner-based kinematic analysis, flexural toppling and wedge failure were found as the main hazardous instability mechanisms in Pitigliano. Finally, the conservation criticalities were identified and a pilot monitoring system was installed in a sector highly susceptible to block detachment

A combined field/remote sensing approach for characterizing landslide risk in coastal areas

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Understanding the key factors controlling slope failure mechanisms in coastal areas is the first and most important step for analyzing, reconstructing and predicting the scale, location and extent of future instability in rocky coastlines. Different failure mechanisms may be possible depending on the influence of the engineering properties of the rock mass (including the fracture network), the persistence and type of discontinuity and the relative aspect or orientation of the coastline. Using a section of the North Coast of Cornwall, UK, as an example we present a multi-disciplinary approach for characterizing landslide risk associated with coastal instabilities in a blocky rock mass. Remotely captured terrestrial and aerial LiDAR and photogrammetric data was interrogated using Geographic Information System (GIS) techniques to provide a framework for subsequent analysis, interpretation and validation. The remote sensing mapping data was used to define the rock mass discontinuity network of the area and to differentiate between major and minor geological structures controlling the evolution of the North Coast of Cornwall. Kinematic instability maps generated from aerial LiDAR data using GIS techniques and results from structural and engineering geological surveys are presented. With this method, it was possible to highlight the types of kinematic failure mechanism that may generate coastal landslides and highlight areas that are more susceptible to instability or increased risk of future instability. Multi-temporal aerial LiDAR data and orthophotos were also studied using GIS techniques to locate recent landslide failures, validate the results obtained from the kinematic instability maps through site observations and provide improved understanding of the factors controlling the coastal geomorphology. The approach adopted is not only useful for academic research, but also for local authorities and consultancy's when assessing the likely risks of coastal instability

Applications of Photogrammetry for Environmental Research

ISPRS International Journal of Geo-Information: special issue entitled "Applications of Photogrammetry for Environmental Research