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Number of grains after failure_
| Total number of grains | Number of the smallest grains | Number of middle grains | Number of the biggest grains | |
| Brenna | 19,888 | 19,879 | 8 | 1 |
| Mucharz | 23,384 | 23,377 | 4 | 3 |
| Radków | 33790 | 33,764 | 14 | 12 |
| Tumlin | 152,953 | 152,944 | 8 | 1 |
Comparison of failure patterns in DEM modeling (initial model, and model just after the failure - view of bonds between particles) and in laboratory (laboratory failure)_
| Type | Initial numerical model | Numerical failure | Laboratory failure |
|---|---|---|---|
| Brenna sample BR2 | |||
| Mucharz sample MU1 | |||
| Radków sample RAD1 | |||
| Tumlin sample TU2 |
Range of results of geomechanical laboratory tests (mean values in brackets)_
| Lithological type | ρ (kg/m3) | UCS (MPa) | E (GPa) | ν (−) |
|---|---|---|---|---|
| Gogula sandstones from Brenna | 2391 – 2444 (2429) | 99 – 107 (102) | 20.2 – 21.8 (20.8) | 0.21 – 0.25 (0.22) |
| Krosno sandstones from Mucharz | 2627 – 2668 (2655) | 138 – 153 (143) | 26.6 – 31.8 (29.2) | 0.18 – 0.23 (0.19) |
| Joint sandstones from Radków | 2119 – 2172 (2142) | 55 – 60 (58) | 22.5 – 24.9 (23.4) | 0.20 – 0.29 (0.24) |
| Sandstones from Tumlin | 2355 – 2480 (2448) | 115 – 128 (123) | 26.2 – 29.4 (27.4) | 0.22 – 0.28 (0.25) |
Detailed parameters of numerical models of sandstones_
| Sandstone 1 Brenna | Sandstone 2 Mucharz | Sandstone 3 Radków | Sandstone 4 Tumlin | |
| Sample geometry | Cylinder: | Cylinder: | Cylinder: | Cylinder: |
| Particles radii | 0.25 – 2.0 mm | 0.25 – 0.5 mm | 0.25 – 1.0 mm | 0.125 – 0.5 mm |
| Particles density | 2429 kg/m3 | 2655 kg/m3 | 2142 kg/m3 | 2448 kg/m3 |
| Initial number of particles | 82,266 | 339,324 | 150,653 | 1,155,851 |
| Initial number of bonds | 297,847 | 821,488 | 500,024 | 3,831,657 |
| Time step | 1.23×10−5s | 8.32×10−6s | 1.06×10−5s | 5.14×10−6s |
| Parameters of bonds : | Eb = 5 284 MPa | Eb= 50 258 MPa | Eb = 12 492 MPa | Eb = 15 144 MPa |
| Stroke rate | 0.2 mm/s | 0.2 mm/s | 0.2 mm/s | 0.2 mm/s |
| Computational time | 287 min | 667 min | 335 min | 1440 min |
| Number of processors | 92 | 228 | 93 | 320 |
Comparison between crucial macroscopic parameters used for model calibration_ ‘Sim’ stands for simulation result and ‘lab’ stands for result from the laboratory experiment_
| Selected test | E (GPa) | UCS (MPa) | ez cr (%) | ν (−) |
|---|---|---|---|---|
| Brenna sample BR2 | Sim: 20.8 | Sim: 98 | Sim: 0.51 | Sim: 0.21 |
| Mucharz sample MU1 | Sim: 29.2 | Sim: 136 | Sim: 0.47 | Sim: 0.19 |
| Radków sample RAD1 | Sim: 23.4 | Sim: 61 | Sim: 0.28 | Sim: 0.21 |
| Tumlin sample TU2 | Sim: 27.4 | Sim: 118 | Sim: 0.46 | Sim: 0.26 |