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![Comparison of the results from drained triaxial and plane strain tests on sand [18] and true-triaxial tests on Skarpa sand.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/6473795f4e662f30ba53f84c/j_sgem-2021-0015_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6AP2G7AKOUXAVR44%2F20251206%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251206T134711Z&X-Amz-Expires=3600&X-Amz-Signature=5dda9581db82844ba15e4b81aafd853e8db6e06d152bab045b2bdd7d95bb305a&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
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Figure 17

Average relative difference of parameters κ and intermediate principal stress σ2, determined by the two approaches: full set of principal stresses and Vikash and Prashant proposal, for Drucker–Prager, Lade–Duncan and Matsuoka–Nakai failure criteria_
| vκ | vσ2 | |
|---|---|---|
| Drucker–Prager |
|
|
| Lade–Duncan |
|
|
| Matsuoka–Nakai |
|
|
The linear fits κexp(ϕps)and the corresponding statistics Pearson's correlation coefficients_
| Linear fit | Pearson's coefficient r | |
|---|---|---|
| Drucker–Prager |
| rD-P = 0.970 |
| Lade–Duncan |
| rL-D = 0.993 |
| Matsuoka–Nakai |
| rM-N = 0.997 |
Characteristics of peak strength state for the tested samples_
| Test | σ1max [kPa] | σ2 [kPa] | σ3 [kPa] | p [kPa] | q [kPa] | b [ − ] | θ [ ° ] |
|---|---|---|---|---|---|---|---|
| 009_17_MC_5 | 1402 | 653 | 391 | 815 | 909 | 0.26 | 14.46 |
| 033_17_MC_14 | 1072 | 479 | 293 | 615 | 705 | 0.24 | 13.21 |
| 012_18_MC_21 | 1184 | 459 | 292 | 645 | 821 | 0.19 | 10.14 |
| 013_18_MC_22 | 678 | 262 | 146 | 362 | 485 | 0.22 | 11.97 |
| 010_18_MC_19 | 902 | 355 | 195 | 484 | 642 | 0.23 | 12.46 |
| 001_18_MC_15 | 870 | 332 | 191 | 464 | 621 | 0.21 | 11.35 |
| 010_15_MC_1 | 1291 | 529 | 278 | 699 | 914 | 0.25 | 13.76 |
| 009_18_MC_18 | 1483 | 528 | 292 | 768 | 1092 | 0.20 | 10.78 |
| 008_18_MC_17 | 1396 | 506 | 295 | 732 | 1012 | 0.19 | 10.40 |
| 028_17_MC_12 | 287 | 109 | 52 | 149 | 212 | 0.24 | 13.44 |
| 031_17_MC_13 | 508 | 191 | 99 | 266 | 372 | 0.22 | 12.38 |
Initial test conditions_
| Test | e | ID | σc3[kPa] | ec |
| nc |
|---|---|---|---|---|---|---|
| 009_17_MC_5 | 0.585 | 0.376 | 391 | 0.563 | 0.465 | 0.36 |
| 033_17_MC_14 | 0.559 | 0.482 | 293 | 0.548 | 0.527 | 0.354 |
| 012_18_MC_21 | 0.541 | 0.555 | 292 | 0.532 | 0.592 | 0.347 |
| 013_18_MC_22 | 0.519 | 0.645 | 146 | 0.514 | 0.665 | 0.339 |
| 010_18_MC_19 | 0.517 | 0.653 | 195 | 0.508 | 0.690 | 0.337 |
| 001_18_MC_15 | 0.521 | 0.637 | 191 | 0.499 | 0.727 | 0.333 |
| 010_15_MC_1 | 0.496 | 0.739 | 278 | 0.490 | 0.763 | 0.329 |
| 009_18_MC_18 | 0.488 | 0.771 | 292 | 0.480 | 0.804 | 0.324 |
| 008_18_MC_17 | 0.489 | 0.767 | 295 | 0.476 | 0.820 | 0.322 |
| 028_17_MC_12 | 0.467 | 0.857 | 52 | 0.462 | 0.878 | 0.316 |
| 031_17_MC_13 | 0.469 | 0.849 | 99 | 0.462 | 0.878 | 0.316 |
Characteristic parameters of Drucker–Prager, Matsuoka–Nakai and Lade–Duncan soil failure criteria, obtained from direct stress measurements (A) and the associated flow rule assuming plane strain conditions (B)_
| Test | A. Direct stress measurements Eqs. (15)–(18) | B. Flow rule and plane strain condition Eqs. (25)–(27) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ϕps |
|
|
|
|
|
|
|
|
| |
| 009_17_MC_5 | 34.3° | 0.21 | 11.7 | 40.9 | 1181.5 | 740.4 | 896.5 | 0.179 | 11.7 | 39.6 |
| 033_17_MC_14 | 34.8° | 0.22 | 11.9 | 41.7 | 904.8 | 560.4 | 682.5 | 0.181 | 11.8 | 40.0 |
| 012_18_MC_21 | 37.2° | 0.25 | 12.5 | 45.7 | 1007.5 | 588.0 | 738 | 0.190 | 12.3 | 42.5 |
| 013_18_MC_22 | 40.2° | 0.26 | 13.2 | 49.4 | 583.8 | 314.6 | 412 | 0.202 | 13.1 | 46.3 |
| 010_18_MC_19 | 40.1° | 0.26 | 13.1 | 49.0 | 776.3 | 419.3 | 548.5 | 0.201 | 13.1 | 46.2 |
| 001_18_MC_15 | 39.8° | 0.26 | 13.1 | 49.0 | 747.8 | 407.6 | 530.5 | 0.200 | 13.0 | 45.7 |
| 010_15_MC_1 | 40.2° | 0.25 | 13.1 | 48.6 | 1111.5 | 599.1 | 784.5 | 0.202 | 13.1 | 46.3 |
| 009_18_MC_18 | 42.1° | 0.27 | 13.8 | 53.4 | 1287.1 | 658.1 | 887.5 | 0.209 | 13.7 | 49.1 |
| 008_18_MC_17 | 40.6° | 0.27 | 13.4 | 50.9 | 1203.9 | 641.7 | 745.5 | 0.203 | 13.2 | 46.9 |
| 028_17_MC_12 | 43.9° | 0.27 | 14.3 | 55.3 | 251.0 | 122.1 | 169.5 | 0.215 | 14.3 | 52.0 |
| 031_17_MC_13 | 42.4° | 0.27 | 13.8 | 52.9 | 441.3 | 224.3 | 303.5 | 0.209 | 13.7 | 46.5 |
The linear fits κexp(IDc) {\kappa ^{\exp }}\left( {I_D^c} \right) and the corresponding Pearson's correlation coefficients_
| Linear fit | Pearson's coefficient r | |
|---|---|---|
| Drucker–Prager |
| rD-P = 0.94 |
| Lade–Duncan |
| rL-D = 0.96 |
| Matsuoka–Nakai |
| rM-N = 0.96 |
Parameters of Skarpa sand_
| Specific density [kg/m3] | 2650 |
| Mean particle size [mm] | D50 - 0.42 |
| Uniformity coefficient [ − ] | U = 2.5 |
| Minimum void ratio [ − ] | emin = 0.432 |
| Maximum void ratio [ − ] | emax = 0.677 |