TOWARDS AN ADVANCED GEOTECHNICAL MODELLING OF BLOCK-IN-MATRIX ROCK FOR ROBUST TUNNEL DESIGN AND CONSTRUCTION

АУТОР(И) / AUTHOR(S): Ksenija Micić , Novak Joksimović , Miloš Marjanović , Vojkan Jovičić, Jelena Ninić 

Download Full Pdf   

DOI:  10.46793/ACUUS2025.2.3.99

САЖЕТАК / ABSTRACT:

Block-in-matrix rock assemblages, also known as ’bimrocks’, represent structurally complex units consisting of hard rock blocks embedded in a soft matrix, with both components differing in geological origin, lithology, rheology and geometry. Considered geotechnically complex formations and being characterized by internal heterogeneity and multi-level spatial variability, such formations are extremely demanding to model using conventional geotechnical approaches. Underground construction, including urban tunnelling in such heterogeneous environments poses numerous challenges, with the most significant ones being high stratal disruptions, stress concentrations at the interface between blocks and matrix, and the inability to accurately predict the behaviour of the rock mass. Besides geological formation, structural analysis and geomechanical characterization, previous studies have only explored methods for probabilistic generation of various block configurations within the rock mass. To tackle the bimrock as an underexplored issue, we present a methodology for up-to-date bimrock ground modelling including lithological and mechanical parameter spatial variability assessment, paired with numerical simulations for the underground construction. Employing the three main modelling components – voxel based geological model, conditional random field parameter model and FEM numerical model, this study aims at introducing a novel, automated and reliable approach for block-in-matrix modelling. It presents an innovative framework for geotechnical modelling of bimrocks, with significant potential for further improvement in accuracy and functionality of the modelling components, as well as the identification of the most sensitive modelling parameters.

КЉУЧНЕ РЕЧИ / KEYWORDS:

block-in-matrix, ground model, numerical simulation, conditional random field, tunnelling

ПРОЈЕКАТ / ACKNOWLEDGEMENT:

This research is supported by the Science Fund of the Republic of Serbia, Project No. 345 – Digital and Numerical Model Integration for Optimization in Geotechnics – DiNum-GEO. Authors are partially supported by Serbian Ministry of Science, Technological Development and Innovation via Project 200092.

ЛИТЕРАТУРА / REFERENCES:

• Guo, S., Wei, Q., Qi, S., Xue, L., Zheng, B., Wang, H., Li, J., Song, S., Liang, N., Zou, Y. & Huang, Z. (2024). Research progress on the geomechanical properties of block-in-matrix rocks. Materials, 17(5), 1167. https://doi.org/10.3390/ma17051167.
• Heße, F., Prykhodko, V., Schlüter, S., & Attinger, S. (2014). Generating random fields with a truncated power-law variogram: A comparison of several numerical methods. Environmental Modelling & Software, 55, 32–48. https://doi.org/10.1016/j.envsoft.2014.01.013.
• Kezdi, A. (1974). Handbook of Soil Mechanics. Elsevier.
• Koloski, J., Schwarz, S., & Tubbs, D. (1989). Geotechnical properties of geologic materials. Engineering Geology in Washington, Bulletin 78(1). Washington Division of Geology and Earth Resources.
• Medley, E. W. (1994). The engineering characterization of melanges and similar block-in-matrix rocks (bimrocks). Doctoral dissertation. University of California, Berkeley
• Medley, E. & Lindquist, E. (1995). The engineering significance of the scale-independence of some Franciscan melanges in California, USA, The 35th U.S. Symposium on Rock Mechanics (USRMS), Reno, Nevada
• Müller, S., Schüler, L., Zech, A., & Heße, F. (2022). GSTools v1.3: A toolbox for geostatistical modelling in Python. Geoscientific Model Development, 15, 3161–3182. https://doi.org/10.5194/gmd-15-3161-2022.
• Napoli, M. L., Barbero, M., Ravera, E., & Scavia, C. (2018). A stochastic approach to slope stability analysis in bimrocks. International Journal of Rock Mechanics and Mining Sciences, 101, 41–49. https://doi.org/10.1016/j.ijrmms.2017.11.009.
• Napoli, M. L., Milan, L., Barbero, M., & Scavia, C. (2020). Identifying uncertainty in estimates of bimrocks volumetric proportions from 2D measurements. Engineering Geology, 278, 105831. https://doi.org/10.1016/j.enggeo.2020.105831.
• Napoli, M. L., Barbero, M., & Scavia, C. (2021). Tunneling in heterogeneous rock masses with a block-in-matrix fabric. International Journal of Rock Mechanics and Mining Sciences, 138, 104655. https://doi.org/10.1016/j.ijrmms.2021.104655.
• Napoli, M. L., Milan, L., Barbero, M., & Medley, E. (2022). Investigation of virtual bimrocks to estimate 3D volumetric block proportions from 1D boring measurements. Geosciences, 12(11), 405. https://doi.org/10.3390/geosciences12110405.
• Napoli, M. L., Milan, L., Barbero, M., & Medley, E. (2023). Application of the point counting technique for estimating the VBP of geotechnically complex formations (Bimrocks/Bimsoils). In 15th ISRM Congress, Salzburg, Austria.
• Obrzud, R., & Truty, A. (2012). The Hardening Soil Model – A Practical guidebook. Z Soil.PC 100701 report.
• Rabcewicz, L. (1964). The New Austrian Tunneling Method (NATM). Water Power, 16(8), 453–457.
• Wackernagel, H. (2003). Multivariate geostatistics: An introduction with applications (3rd ed.). Springer. https://doi.org/10.1007/978-3-662-05294-5.
• Xue, J., & Nag, D. (2011). Reliability analysis of shallow foundations subjected to varied inclined loads. Geotechnical safety and risk: Proceedings of the ISGSR 2011, 377–384. Bundesanstalt für Wasserbau.
• Zhang, H., Huang, C., Wang, L., Cao, Y., & Boldini, D. (2025). Estimation of volumetric block proportions from 1D boring of bim-materials considering different block forms. Engineering Geology, 353, 108094. https://doi.org/10.1016/j.enggeo.2025.108094.