Table 2.

Experimental protocol implemented during this study

B2T1N35D12B2T2N40D12B2T3N45D12
  1. Ramping up the vertical stress to 35 MPa.

  2. Start shearing until it reaches 30 mm of displacement.

  3. Stop shearing and measure the static transmissibility.

  4. Decrease the vertical stress to 11.5 MPa and then measure the static transmissibility.

  5. Re-start shearing at 11.5 MPa until reaches it 50 mm of displacement and then measure the static transmissibility.

  6. Increase the vertical stress to 35 MPa and measure the static transmissibility.

  7. At 50 mm of displacement, increase the shear rate to 1 mm min–1 and continue shearing until it reaches 120 mm of displacement.

  8. Measure the static transmissibility at the 120 mm displacement.

  1. Ramping up the vertical stress to 40 MPa.

  2. Start shearing until it reaches the peak strength (c. 15 mm).

  3. At the peak, halt shearing and measure the static transmissibility.

  4. Decrease the vertical stress to 6 MPa and measure the static transmissibility.

  5. Re-start shearing at 6 MPa until it reaches 30 mm of displacement and then measure the static transmissibility.

  6. Increase the vertical stress to 13 MPa and measure the static transmissibility.

  7. Re-start shearing at 13 MPa until it reaches 40 mm and then measure the static transmissibility.

  8. Increase the vertical stress to 35 MPa and measure the static transmissibility.

  9. Re-start shearing at 35 MPa until it reaches 50 mm of displacement and measure the static transmissibility.

  10. Once again, measure the static transmissibility at a higher injection pressure of 0.2 MPa.

  11. Increase both the vertical stress to 40 MPa and the shear rate to 1 mm min–1, then continue shearing up to 120 mm of displacement.

  1. Measure the pre-sheared (intact) static transmissibility at 5, 21 and 45 MPa.

  2. Start shearing until it reaches the peak strength (c. 18.5 mm).

  3. At the peak, decrease the vertical stress to 6 MPa and measure the static transmissibility.

  4. Re-start shearing at 6 MPa until it reaches 30 mm of displacement.

  5. Increase the vertical stress to 45 MPa and start shearing from 30 to 40 mm. Then reverse displacement to 30 mm.

  6. At 30 mm, decrease the vertical stress to 35 MPa and start shearing from 30 to 40 mm. Measure the static transmissibility and after that reverse displacement to 30 mm.

  7. Once more, at 30 mm, decrease the vertical stress to 6 MPa and start shearing from 30 to 40 mm. Then reverse displacement to go back to 30 mm.

  8. At 30 mm of displacement, increase both the vertical stress to 45 MPa and the shear rate to 1 mm min–1, and then continue shearing to 120 mm displacement.