Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments
This paper provides research that shows that the scale and quantification of the degree of fracturing in a rock mass should and can be considered when estimating geological strength index (GSI) ratings for rock mass strength and deformability estimates. In support of this notion, a brief review is p...
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2025-07-01
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| author | Paul Schlotfeldt Jose (Joe) Carvalho Brad Panton |
| author_facet | Paul Schlotfeldt Jose (Joe) Carvalho Brad Panton |
| author_sort | Paul Schlotfeldt |
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| description | This paper provides research that shows that the scale and quantification of the degree of fracturing in a rock mass should and can be considered when estimating geological strength index (GSI) ratings for rock mass strength and deformability estimates. In support of this notion, a brief review is provided to demonstrate why it is imperative that scale is considered when using GSI in engineering design. The impact of scale and scale effects on the engineering response of a rock mass typically requires a definition of fracture intensity relative to the volume or size of rock mass under consideration and the relative scale of the project being built. In this research three volume scales are considered: the volume of a structural domain, a representative elemental REV, and unit volume. A theoretical framework is established that links these three volume scales together, how they are estimated, and how they relate to parameters used to estimate engineering behaviour. Analysis of data from several examples and case histories for real rock masses is presented that compares and validates the use of a new and innovative but practical method (a sphere of unit volume) to estimate fracture intensity parameters VFC or P30 (fractures/m<sup>3</sup>) and P32 (fracture area—m<sup>2</sup>/m<sup>3</sup>) that is included on the vertical axis of the volumetric V-GSI chart. The research demonstrates that the unit volume approach to calculating VFC and P32 used in the V-GSI system compares well with other methods of estimating these two parameters (e.g., discrete fracture network (DFN) modelling). The research also demonstrates the reliability of the VFC-correlated rating scale included on the vertical axis of the V-GSI chart for use in estimating first-order strength and deformability estimates for rock masses. This quantification does not negate or detract from geological logic implicit in the original graphical GSI chart. |
| format | Article |
| id | doaj-art-fd7207d2a21e485ab78e548d62bf4110 |
| institution | Kabale University |
| issn | 2076-3417 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Applied Sciences |
| spelling | doaj-art-fd7207d2a21e485ab78e548d62bf41102025-08-20T04:00:50ZengMDPI AGApplied Sciences2076-34172025-07-011515821910.3390/app15158219Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) AssessmentsPaul Schlotfeldt0Jose (Joe) Carvalho1Brad Panton2WSP Canada Inc., 1631 Dickson Avenue, Suite 700, Kelowna, BC V1Y 0B5, CanadaWSP Canada Inc., 1631 Dickson Avenue, Suite 700, Kelowna, BC V1Y 0B5, CanadaWSP Canada Inc., 1631 Dickson Avenue, Suite 700, Kelowna, BC V1Y 0B5, CanadaThis paper provides research that shows that the scale and quantification of the degree of fracturing in a rock mass should and can be considered when estimating geological strength index (GSI) ratings for rock mass strength and deformability estimates. In support of this notion, a brief review is provided to demonstrate why it is imperative that scale is considered when using GSI in engineering design. The impact of scale and scale effects on the engineering response of a rock mass typically requires a definition of fracture intensity relative to the volume or size of rock mass under consideration and the relative scale of the project being built. In this research three volume scales are considered: the volume of a structural domain, a representative elemental REV, and unit volume. A theoretical framework is established that links these three volume scales together, how they are estimated, and how they relate to parameters used to estimate engineering behaviour. Analysis of data from several examples and case histories for real rock masses is presented that compares and validates the use of a new and innovative but practical method (a sphere of unit volume) to estimate fracture intensity parameters VFC or P30 (fractures/m<sup>3</sup>) and P32 (fracture area—m<sup>2</sup>/m<sup>3</sup>) that is included on the vertical axis of the volumetric V-GSI chart. The research demonstrates that the unit volume approach to calculating VFC and P32 used in the V-GSI system compares well with other methods of estimating these two parameters (e.g., discrete fracture network (DFN) modelling). The research also demonstrates the reliability of the VFC-correlated rating scale included on the vertical axis of the V-GSI chart for use in estimating first-order strength and deformability estimates for rock masses. This quantification does not negate or detract from geological logic implicit in the original graphical GSI chart.https://www.mdpi.com/2076-3417/15/15/8219geological strength index (GSI)sale and scale effectsstructural domainsrepresentative elemental volume (REV)volumetric fracture counts (VFC or P30)fracture area per unit volume (P32) |
| spellingShingle | Paul Schlotfeldt Jose (Joe) Carvalho Brad Panton Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments Applied Sciences geological strength index (GSI) sale and scale effects structural domains representative elemental volume (REV) volumetric fracture counts (VFC or P30) fracture area per unit volume (P32) |
| title | Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments |
| title_full | Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments |
| title_fullStr | Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments |
| title_full_unstemmed | Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments |
| title_short | Scale Considerations and the Quantification of the Degree of Fracturing for Geological Strength Index (GSI) Assessments |
| title_sort | scale considerations and the quantification of the degree of fracturing for geological strength index gsi assessments |
| topic | geological strength index (GSI) sale and scale effects structural domains representative elemental volume (REV) volumetric fracture counts (VFC or P30) fracture area per unit volume (P32) |
| url | https://www.mdpi.com/2076-3417/15/15/8219 |
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