Determination of rock type and moisture content in flysch using TLS intensity in the Elerji quarry (south-west Slovenia)
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Terrestrial laser scanning (TLS) was performed in tectonically undisturbed flysch in the Elerji quarry (south-west Slovenia), which represents heterogeneous rock mass with alternation of marlstone and sandstone beds. A 9.3-m-thick lithological profile was measured in detail and then compared to TLS values of reflected intensity and mineralogical composition of general marlstones and sandstones. The results showed distinguishable differences between the intensity values of marlstones and sandstones, as these two groups were found to be statistically different. It was also possible to discriminate these units with regard to their moisture content, as different values were observed for combinations of lithology and moisture content. Correlations of intensity and RGB (red, green, blue) values for the mineralogical composition of marlstones and sandstones revealed a good correlation of intensity with combined calcite and quartz content; however, such correlation is valid only for sandstones due to their bigger grain size. Larger quartz grains can scatter the laser beam and lower the correlation. The results showed that acquiring data from heterogeneous rock mass using TLS could be used for the geotechnical engineering classification of distant, inaccessible outcrops and excavated faces, based on the well-established RMR (Rock Mass Rating) and GSI (Geological Strength Index) rock mass classification systems. Both RMR and GSI classification systems classify rock mass based on rock composition, structure and surface conditions of discontinuities. Lithological segmentation of heterogeneous rocks presents, therefore, an important input parameter for their further classification.
KeywordsFlysch rock mass TLS Signal intensity Reflectance South-west Slovenia Moisture content Rock mass characterisation
The research for using TLS for lithology logging of thin-bedded heterogeneous rock mass by analysing the intensity values of the reflected laser beam was performed between 2011 and 2016 as part of the Elea iC Research & Development group NTg2 (New Technologies in Geomatics and Geomechanics), which was co-financed by the European Union. The analysis included scanned faces of underground and ground excavations, like tunnel and quarry faces.
The authors express their thanks to Dr. Matej Dolenec for the performance of XRD analysis and DFG Consulting for supporting the performance and knowledge of terrestrial laser scanning.
- Barton N, Lien R, Lunde J (1974) Engineering classification of rock masses for the design of rock support. Rock Mechanics, 6(4), pp. 189–236Google Scholar
- Bieniawski, ZT (1989) Engineering Rock Mass Classifications: A Complete Manual for Engineers and Geologists in Mining, Civil, and Petroleum Engineering, A Wiley-Interscience publication. John Wiley & Sons, Hoboken, NJ, USAGoogle Scholar
- Carrea D, Abellan A, Humair F et al (2016) Correction of terrestrial LiDAR intensity channel using Oren–Nayar reflectance model: an application to lithological differentiation. ISPRS J Photogramm Remote Sens 113(supplement C):17–29. https://doi.org/10.1016/j.isprsjprs.2015.12.004 CrossRefGoogle Scholar
- Feng Q, Röshoff K (2015) A survey of 3D laser scanning techniques for application to rock mechanics and rock engineering. In: Ulusay R (ed) The ISRM suggested methods for rock characterization, testing and monitoring: 2007–2014. Springer International Publishing, Cham, pp 265–293. https://doi.org/10.1007/978-3-319-07713-0_25 Google Scholar
- Lu J, Georghiades AS, Rushmeier H, Dorsey J, Xu C (2005) Synthesis of material drying history: phenomenon modeling, transferring and rendering. In: Proceedings of the first Eurographics conference on natural phenomena (NPH’05). Eurographics Association, Aire-la-Ville, Switzerland, pp 7–16Google Scholar
- Marinos V, Marinos P, Hoek E (2007) Geological Strength Index (GSI). A characterization tool for assessing engineering properties for rock masses. In: Underground Works under Special Conditions. Proceedings of the ISRM Workshop W1, Madrid, Spain, 6–7 July 2007, pp 13–21. https://doi.org/10.1201/NOE0415450287.ch2
- Pfeifer N, Dorninger P, Haring A et al (2007) Investigating terrestrial laser scanning intensity data: quality and functional relations. In: Proceedings of the 8th conference on Optical 3-D Measurement Techniques, Zurich, Switzerland, July 2007, pp 328–337Google Scholar
- Pleničar M, Polšak A, Šikić D (1969) Osnovna geoloska karta SFRJ. L 33-88, Trst (Trieste) [kartografsko gradivo], 1:100 000. Beograd: Zvezni geoloski zavodGoogle Scholar
- Pleničar M, Polšak A, Šikić D (1973) Tolmac za list Trst: L 33-88: Socialisticna federativna republika Jugoslavija, osnovna geoloska karta, 1:100 000. Beograd: Zvezni geoloski zavodGoogle Scholar
- Ranasooriya J (2009) The reliability of rock mass classification systems as underground excavation support design tools. Ph.D. thesis, Curtin University of Technology, Perth, AustraliaGoogle Scholar
- Read SAL, Perrin ND, Richards L (2000) Assessment of New Zealand greywacke rock masses with the Hoek-Brown failure criterion. In: Proceedings of the ISRM International Symposium, Melbourne, Australia, 19–24 November. International Society for Rock MechanicsGoogle Scholar
- Riegl LMS GmbH (2011) 3D Terrestrial Laser Scanner Riegl VZ-400: General Description and Data InterfacesGoogle Scholar
- Rožič B, Verbovšek T, Vrabec M (2014) Povzetki in ekskurzije/Abstracts and field trips. In: 4. slovenski geološki kongres, Ankaran, 8.-10. oktober 2014. Ljubljana: Naravoslovnotehniska fakultetaGoogle Scholar
- Slob S, Hack HRGK, van Knapen B et al (2004) Automated identification and characterisation of discontinuity sets in outcropping rock masses using 3D terrestrial laser scan survey techniques. In: Schubert W (ed) Proceedings of the ISRM regional symposium EUROCK 2004 and 53rd Geomechanics colloquy: rock engineering and practice, Salzburg, Austria, 7–9 October 2004. Verlag Glückauf, Essen, pp 439–443Google Scholar
- Sturzenegger M (2010) Multi-scale characterization of rock mass discontinuities and rock slope geometry using terrestrial remote sensing techniques. Ph.D. thesis, Simon Fraser University, CanadaGoogle Scholar