Monitoring of strain and temperature in an open pit using brillouin distributed optical fiber sensors

Marble quarries are quite dangerous environments in which rock falls may occur. As many workers operate in these sites, it is necessary to deal with the matter of safety at work, checking and monitoring the stability conditions of the rock mass. In this paper, some results of an innovative analysis method are shown. It is based on the combination of Distributed Optical Fiber Sensors (DOFS), digital photogrammetry through Unmanned Aerial Vehicle (UAV), topographic, and geotechnical monitoring systems. Although DOFS are currently widely used for studying infrastructures, buildings and landslides, their use in rock marble quarries represents an element of peculiarity. The complex morphologies and the intense temperature range that characterize this environment make this application original. The selected test site is the Lorano open pit which is located in the Apuan Alps (Italy); here, a monitoring system consisting of extensometers, crackmeters, clinometers and a Robotic Total Station has been operating since 2012. From DOFS measurements, strain and temperature values were obtained and validated with displacement data from topographic and geotechnical instruments. These results may provide useful fundamental indications about the rock mass stability for the safety at work and the long-term planning of mining activities

Slope stability analyses and geological risk reduction: two case studies, from engineering-geological characterization to rockfall runout modeling with intervention proposal

Rock slope instability is a major risk to human life, often leading to economic losses, property damage and maintenance costs, as well as injuries or death. Because the rock mass behavior is significantly governed by the presence of joints or other discontinuities, several types of slope failure such as plane failure, toppling failure, wedge failure, buckling failure and circular failure are often observed. These failures may be gradual with very slow movement of the sliding block or instantaneous without much warning. To understand this process, it is important to study the rock slope (geological data collections, geotechnical collections, data kinematic stability analysis, runout analyses…) This work is divided in two cases of studies, which are both complementary to study a rock slope stability: 1. The first case of study is an underground quarry of marble located in Levigliani (Luca, Italy), which we did a classification of the rockmass based on the empirical method of Bieniawski (RMR) and also a kinematic analysis of the conditions of stability with the software Rocscience Dips, after a 3D stability analysis was used by the software Rocscience Unwedge which was developed specifically for the use in underground rock mining; 2. For the second case of study is an ex open pit quarry of limestone located in Vecchiano (Pisa, Italy), in which we calculated the trajectories of falling blocks with an advanced numerical method (Rockyfor3D): rigid body approach, capable of analyzing the propagation phase of the volumes detached from the slope; methodology that allowed to simulate the rockfall phenomena through the production of block rebound mechanisms during the descent towards the slope and also we gave an intervention proposal to mitigate the risk; the localization and sizing of the blocks was done by a Digital Terrain Model (DTM)

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

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

Elevation modelling and palaeo-environmental interpretation in the Siwa area (Egypt): Application of SAR interferometry and radargrammetry to COSMO-SkyMed imagery

PublishedJournal Article© 2015 Elsevier B.V. Digital elevation models produced from COSMO-SkyMed imagery were used to delineate palaeo-drainage in a wide area surrounding the Siwa and Al-Jaghbub oases of the western Sahara Desert (Egypt and Libya).This new generation of synthetic aperture radar imagery is suitable for this purpose because of its high spatial resolution and capacity to penetrate dry surface sediments. Different techniques such as radar interferometry and radargrammetry were used to produce digital elevation models. These were assessed for accuracy and then combined to produce a single elevation model of the area. The resulting elevation model was used to support the geological study and palaeo-environmental interpretation of the area. It revealed buried features of the landscape, including inactive palaeo-drainage systems. Drainage features were extracted from the elevation model using geographical information systems; results were combined and assessed with respect to geological field data, as well as data from the literature. Previous studies in the area suggest that a wide river, probably the old Nile River, flowed into the Libyan palaeo-Sirte before the Late Messinian drawdown of the Mediterranean Sea. During the Late Messinian lowering of the sea the fluvial system changed shape and carved deep canyons throughout north-eastern Africa. The reported findings on the key Siwa area were used to precisely delineate the physiography of the modern drainage network and to confirm findings from our previous geological research in the area.We gratefully acknowledge Ruggero Matteucci and Johannes Pignatti (La Sapienza, University of Rome), Francesco Checchi (ENI S.p.A., IOEC), Filippo Bonciani and Debora Graziosi (University of Siena) for their collaboration. Research was supported by the ASI (Id 2262) in the framework of the COSMO-SkyMed Announcement of Opportunity project “Application of COSMO-SkyMed data for geological researches in Egypt and Libya”

Open-addressing hashing with unequal-probability keys

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.Part of the present study was undertaken within the framework of the Italian National Research Project PRIN2009, funded by the Ministry of Education, Universities and Research, which involves the collaboration between the University of Siena, ‘La Sapienza’ University of Rome, and USL1 of Massa and Carrara (Mining Engineering Operative Unit – Department of Prevention). The authors acknowledge M. Pellegri and D. Gullì (USL1, Mining Engineering Operative Unit – Department of Prevention), M. Ferrari, M. Profeti and V. Carnicelli (Cooperativa Cavatori Lorano), X. Chaoshui and P.A. Dowd (School of Civil, Environmental and Mining Engineering, University of Adelaide, South Australia) and M. Bocci (Geographike) for their support of this research

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. © 2014 Elsevier Ltd.The authors gratefully acknowledge the assistance of the personnel of the Romana Quarry and particularly Geol. Massimo Corniani. This paper was possible because of support from the Tuscany Region Research Project known as “Health and safety in the quarries of ornamental stones – SECURCAVE”

Application of an integrated geotechnical and topographic monitoring system in the Lorano marble quarry (Apuan Alps, Italy)

PublishedThis is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.geomorph.2015.04.009Accurate slope stability analysis is essential for human activity in high-risk geological contexts. This may, however, not be enough in the case of quarrying where the dynamic and evolving environment also requires effective monitoring. A well-designed monitoring system requires the acquisition of a huge dataset over time, improving knowledge of the study area and helping to refine prediction from stability analysis.This paper reports the implementation of an integrated monitoring system in a marble quarry in the Apuan Alps (Italy) and some of the results obtained. The equipment consists of a traditional geotechnical monitoring system (extensometers, crackmeters and clinometers) and two modern topographic monitoring systems (a terrestrial interferometer and a robotic total station). This work aims to provide in-depth knowledge of the large scale rock mass behaviour as a result of marble exploitation, thereby allowing continuous excavation. The results highlight the importance of integrating different monitoring systems.The present study was undertaken within the framework of the Italian National Research Project PRIN2009, funded by the Ministry of Education, Universities and Research, which involves the collaboration between the University of Siena, “La Sapienza” University of Rome, and USL1 of Massa and Carrara (Mining Engineering Operative Unit - Department of Prevention)