Claudio Vanneschi

The use of an unmanned aerial vehicle for fracture mapping within a marble quarry (Carrara, Italy): photogrammetry and discrete fracture network modelling

ABSTRACT This paper describes the use of a drone in collecting data for mapping discontinuities within a marble quarry. A topographic survey was carried out in order to guarantee high spatial accuracy in the exterior orientation of images. Photos were taken close to the slopes and at different angles, depending on the orientation of the quarry walls. This approach was used to overcome the problem of shadow areas and to obtain detailed information on any feature desired. Dense three-dimensional (3D) point clouds obtained through image processing were used to rebuild the quarry geometry. Discontinuities were then mapped deterministically in detail. Joint attitude interpretation was not always possible due to the regular shape of the cut walls; for every discontinuity set we therefore also mapped the uncertainty. This, together with additional fracture characteristics, was used to build 3D discrete fracture network models. Preliminary results reveal the advantage of modern photogrammetric systems in producing detailed orthophotos; the latter allow accurate mapping in areas difficult to access (one of the main limitations of traditional techniques). The results highlight the benefits of integrating photogrammetric data with those collected through classical methods: the resulting knowledge of the site is crucially important in instability analyses involving numerical modelling.

Geological Application of UAV Photogrammetry and Terrestrial Laser Scanning in Marble Quarrying (Apuan Alps, Italy)

Workplace safety in quarries can be evaluated and improved through an accurate risk assessment of mining activities. Rock slopes stability is dominantly influenced by the structural setting which, in combination with exploitation methods, affects the risk. This paper describes studies carried out in the Apuan Alps, where several quarry walls reach hundreds of meters in height and are dominated by natural slopes with complex morphology. Aim of the present paper is to determine the detailed structural-geological setting of a quarry wall and to identify potentially unstable zones. In such an environmental context, data obtained from engineering-geological surveys, collected at the foot of the slope and along the wall by climbing technicians, may be used for rock mass characterization. This data, which holds important statistical value, has been integrated with other info coming from a terrestrial photogrammetric survey, that was realized using an unmanned aerial vehicle, and from terrestrial laser scanning. The stereoscopic and high resolution images and the 3D model from point clouds have been processed and interpreted in order to provide a deterministic information of the complete slope setting. The geometrical and geo-engineering data was utilized for a stability analysis carried out through a 2D numerical modelling based on the distinct element method. Results of this study have been used to assess the safety conditions necessary to continue the exploitation activities and, eventually, to plan for proper remediation.

Geological 3D modeling for excavation activity in an underground marble quarry in the Apuan Alps (Italy)

The three-dimensional laser scanning technique has recently become common in diverse working environments. Even in geology, where further development is needed, this technique is increasingly useful in tackling various problems such as stability investigations or geological and geotechnical monitoring. Three-dimensional laser scanning supplies detailed and complete geometrical information in short working times, as a result of the acquisition of a large number of data-points that accurately model the detected surfaces. Moreover, it is possible to combine these data with high quality photographic images so as to provide important information for geological applications, as follows. A working approach, that combines terrestrial laser scanning and traditional geological surveys, is presented. A three-dimensional model, that includes information about the geological structure in an underground quarry in the Apuan Alps, is realized. This procedure is adaptable to other geological contexts, and because of its operating speed and accuracy it is invaluable for optimal excavation, in which a proper planning of quarrying activity is vital for safety and commercial reasons.

Integration of Geotechnical and Remote Monitoring Systems for the Analysis and Control of Ground Deformation in Marble Quarrying (Apuan Alps, Italy)

Workplace safety in quarry sites can be evaluated and established through an accurate monitoring of mining activities and slope stability. This last is dominantly influenced by the structural setting which, in combination with exploitation methods, affects the risk. The present paper shows the applied methodologies and the preliminary results obtained from an integrated monitoring system implemented in the Apuan Alps, within a quarry characterized by a buttress shaped remnant of previous excavation activities and accessible from 3 sides. In 1997, a rock fall event occurred in a neighbouring area of the buttress causing the interruption of quarrying activities. With the purpose of controlling the buttress stability, preserving safety conditions, planning proper remediation works and continuing exploitation activities, various monitoring systems have been installed during the years: this paper describes the 3 more recent systems that have been operating for more than 1 year. The instrumentation consists of geotechnical monitoring sensors composed by extensometers and crack-meters, and two topographic systems represented by a terrestrial interferometer and a robotic total station. Results from the 3 monitoring systems highlighted few critical zones whose presence was already known and precautionary measures had already been adopted; their geo-mechanical character is still under study with the aim of establishing the thresholds of risk that separate the natural rock behaviour from any probability of failure.

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

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.

A multi-scale and multi-disciplinary approach for the study and monitoring of rocky coastlines

Abstract from 88th Congress of the Italian Geological Society, 2016-09-07 - 2016-09-09, NaplesAbstract from 88th Congress of the Italian Geological Society, 2016-09-07, 2016-09-09, Naplesbook Edited by D. Calcaterra, S. Mazzoli, F.M. Petti, B. Carmina & A. Zuccari doi: 10.3301/ROL.2016.79

Remote sensing techniques in underground mining: Application of terrestrial LIDAR for stability analysis and optimization of excavation activities

Abstract from 88th Congress of the Italian Geological Society, 2016-09-07 - 2016-09-09, NaplesAbstract from 88th Congress of the Italian Geological Society, 2016-09-07, 2016-09-09, Naplesbook Edited by D. Calcaterra, S. Mazzoli, F.M. Petti, B. Carmina & A. Zuccari doi: 10.3301/ROL.2016.79