Figures


 

Figure 1. Estimated rock strengths from thrust and Schmidt-hammer rebound hardness (Niken-Goya tunnel)

 

 

Figure 2. Estimated rock strengths from torque and Schmidt-hammer rebound hardness (Niken-Goya tunnel)

 

Figure 3. Cutting depth, Cutting force and rock strength estimated using Schmidt-hammer rebound hardness (Maiko tunnel)

 

Figure 4. Estimated rock strengths from thrust and Schmidt-hammer rebound hardness (Maiko tunnel)

 

Figure 5. Estimated rock strengths from torque and Schmidt-hammer rebound hardness (Maiko tunnel)

 

Figure 6. Estimated rock strength from thrust and the ratio of limestone (Culter-Goodman tunnel)