Vance Press
Register Login

Rock Mechanics Letters

cover
Article Menu
Recommend Papers
Effects of temperature, water content, hydraulic pressure, stress level and damage on rock creep and the prolonged stability of deep underground structures Effects of temperature, water content, hydraulic pressure, stress level and damage on rock creep and the prolonged stability of deep underground structures
Advanced Optimisation Of Ground Support Systems for Enhancing Underground Tunnel Stability in Geologically Adverse Conditions Advanced Optimisation Of Ground Support Systems for Enhancing Underground Tunnel Stability in Geologically Adverse Conditions
A comparative study of three types of strength criteria for rocks A comparative study of three types of strength criteria for rocks
Particle flow simulation of crack propagation and penetration in Brazilian disc under uniaxial compression Particle flow simulation of crack propagation and penetration in Brazilian disc under uniaxial compression
Open Access Communication

Introducing Coefficients of Curvature (Cc) and Uniformity (Cu) Based on RQD for Rock Mass Characterization

by Seyed Morteza Davarpanah 1,* ,  Samad Narimani 2 ,  Mohammad Sharghi 3  and  Balázs Vásárhelyi 4
1
Research Institute of Mines and Environment (RIME), Université du Québec en Abitibi-Témiscamingue (UQAT), Rouyn-Noranda, QC J9X5E4, Canada
2
Department of Engineering Geology and Geotechnics, Faculty of Civil Engineering, Budapest University of Technology and Economics, 1111 Budapest, Hungary
3
Department of Energy Resources Engineering, Pukyong National University, Busan 48513, Republic of Korea
4
Department of Engineering Geology and Geotechnics, Faculty of Civil Engineering, Budapest University of Technology and Economics, 1111 Budapest, Hungary
*
Author to whom correspondence should be addressed.
RML  2025 2(1):10; https://doi.org/10.70425/rml.202501.10
Received: 21 November 2024 / Accepted: 19 January 2025 / Published Online: 20 January 2025
View Full-Text
Download PDF

Abstract

This paper proposes a novel approach to rock mass characterization by adapting the coefficient of uniformity (Cu) and coefficient of curvature (Cc) from soil mechanics, redefining their mathematical formulations to align with RQD-based block size measurements. Specifically, Cu and Cc are calculated using D10, D30, and D60, derived from cumulative RQD data, while accounting for the increasing scale of block size distributions in rock masses. An illustrative case study demonstrates the application of this method, yielding insights into block size variability and heterogeneity in rock masses. The proposed coefficients enrich rock mass classification, offering enhanced quantitative tools for engineering and geological analyses.

Keywords: RQD; coefficient of uniformity (Cu); coefficient of curvature (Cc); Rock mass;
Copyright: © 2025 by Davarpanah, Narimani, Sharghi and Vásárhelyi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) (Creative Commons Attribution 4.0 International License). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Show Figures

Share and Cite

ACS Style
Davarpanah, S. M.; Narimani, S.; Sharghi, M.; Vásárhelyi, B. Introducing Coefficients of Curvature (Cc) and Uniformity (Cu) Based on RQD for Rock Mass Characterization. Rock Mechanics Letters, 2025, 2, 10. https://doi.org/10.70425/rml.202501.10
AMA Style
Davarpanah S M, Narimani S, Sharghi M, Vásárhelyi B. Introducing Coefficients of Curvature (Cc) and Uniformity (Cu) Based on RQD for Rock Mass Characterization. Rock Mechanics Letters; 2025, 2(1):10. https://doi.org/10.70425/rml.202501.10
Chicago/Turabian Style
Davarpanah, Seyed M.; Narimani, Samad; Sharghi, Mohammad; Vásárhelyi, Balázs 2025. "Introducing Coefficients of Curvature (Cc) and Uniformity (Cu) Based on RQD for Rock Mass Characterization" Rock Mechanics Letters 2, no.1:10. https://doi.org/10.70425/rml.202501.10
APA Style
Davarpanah, S. M., Narimani, S., Sharghi, M., & Vásárhelyi, B. (2025). Introducing Coefficients of Curvature (Cc) and Uniformity (Cu) Based on RQD for Rock Mass Characterization. Rock Mechanics Letters, 2(1), 10. https://doi.org/10.70425/rml.202501.10

Article Metrics

Article Access Statistics

References

  1. Deere D.U. Technical description of rock cores for engineering purposes. Rock Mechanics and Engineering Geology. 1964; 1(1): 16-22.
  2. Deere D.U, Hendron A.J, Patton F.D, Cording E.J. Design of surface and near surface construction in rock. In: Proceedings of the 8th U.S. Symposium on Rock Mechanics-Failure and Breakage of Rock. New York: American Institute of Mining, Metallurgical and Petroleum Engineers. 1967: 237-302.
  3. Palmström A. Measurements of and correlations between block size and rock quality designation (RQD). Tunneling and Underground Space Technology. 2005; 20(4): 362–377. Doi:10.1016/j.tust.2005.01.005
  4. Somodi G, Vásárhelyi B. Borehole analysis with the modification of RQD value. Geotechnics. 2023; 3(4): 1017-1032. Doi:10.3390/geotechnics3040055
  5. Das B. Principles of Geotechnical Engineering. USA. 2011.
  6. Davarpanah M, Somodi G, Kovács L, Vásárhelyi B. Complex analysis of uniaxial compressive tests of the Mórágy granitic rock formation (Hungary). Studia Geotechnica et Mechanica. 2019; 41(1): 21-32. Doi:10.2478/sgem-2019-0010