On the Design of Permanent Rock Support Using Fibre-Reinforced Shotcrete
2. Design of Shotcrete as Permanent Rock Support
2.1. Design with the Q-Method
2.2. Design with the RMR-Method
2.3. Design with the National Guidelines
2.4. Design with Analytical Equations
3. Experimental Campaign
3.2. Preparation of Specimens
4. Case Study of Tunnel Design
- Design with Q-method: The required energy absorption for the shotcrete was based on the geometry, ESR- and Q-value. First, the required energy absorption was taken from the Q-chart shown in Figure 1 and then converted according to .
- TPL design: Based on the Q-value, a rock class was determined based on the Q-chart. The correlation between rock class and toughness performance level (TPL) was used to determine a required residual strength .
- Australian design: Here, it was assumed that small deformations were expected for Q = 20 and large deformations when Q = 1.5. Hence, the design was based on a residual strength for Q = 20 and an energy absorption for Q = 1.5 based on Australian standards (ACS2010).
- Swedish design: The requirements of the shotcrete were based on a recommended residual strength based on Swedish guidelines .
- Dosage of fibres: Based on the results from the experimental campaign presented in Section 5, the minimum dosage of fibres that fulfilled the design criterion was selected for each design alternative.
5. Results and Discussion
5.1. Experimental Results
5.2. Structural Performance
5.3. Environmental Performance
Data Availability Statement
Conflicts of Interest
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|81–100||Occasional spot bolting.|
|61–80||Local bolts in crown, = 2.5 m, = 50 mm was needed|
|41–60||Systematic bolts in crown and wall, = 1.5–2.0 m, = 50–100 mm and = 30 mm|
|21–40||Systematic bolts in crown and wall, = 1.0–1.5 m, = 100–150 mm and = 100 mm|
|0–20||Systematic bolts in crown and wall, = 1.0–1.5 m, = 150–200 mm and = 150 mm|
|Aggregate 0–2 mm||489||kg/m3|
|Aggregate 0–8 mm||1141||kg/m3|
|Release agent 1||1.6||kg/m3|
|CO2 Eq. to Produce 1 kg of Fibre|
|Global Warming Potential (GWP)||0.88 kg||2.01 kg||2.11 kg|
|Cubes||Beams EN 14488-3 (MPa)||Panels (J)|
|Dramix 4D||30||58/59/62||3.4/4.4/4.9||4.2||3.5/4.4/4.5||4.2||525 */825/927|
|Dramix 3D||Dramix 4D||MiniBar||BarChip|
|—200 J||20||B||30 *||26||20 *||18||14 *||30||3||6|
|—TPL I||20||B||30 *||26||20 *||18||14 *||30||6 *||12|
|—280 J||1.5||D||30 *||26||20 *||18||14 *||30||6 *||12|
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Sjölander, A.; Ansell, A.; Nordström, E. On the Design of Permanent Rock Support Using Fibre-Reinforced Shotcrete. Fibers 2023, 11, 20. https://doi.org/10.3390/fib11020020
Sjölander A, Ansell A, Nordström E. On the Design of Permanent Rock Support Using Fibre-Reinforced Shotcrete. Fibers. 2023; 11(2):20. https://doi.org/10.3390/fib11020020Chicago/Turabian Style
Sjölander, Andreas, Anders Ansell, and Erik Nordström. 2023. "On the Design of Permanent Rock Support Using Fibre-Reinforced Shotcrete" Fibers 11, no. 2: 20. https://doi.org/10.3390/fib11020020