Table 3 Summary of interface friction strength obtained from modified direct shear apparatus with various scale geometries, three vertical stresses, and two-way shearing: (a) Cranial → Caudal; (b) Caudal → Cranial.
L [mm] | H [mm] | (a) Cranial → Caudal | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Cranial first shearing | Caudal second shearing | ||||||||||
σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ϕres [°] | Ψ [°] | σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ϕres [°] | Ψ [°] | ||
6 | 0.3 | 50 | 62.3 | 43.4 | 41.2 | – | 50 | 24.7 | 24.5 | 22.9 | – |
100 | 100.1 | 7.4 | 100 | 52.1 | 3.6 | ||||||
200 | 183.0 | – | 200 | 87.4 | – | ||||||
12 | 0.3 | 50 | 52.7 | 39.2 | 36.4 | – | 50 | 27.2 | 23.8 | 22.4 | – |
100 | 89.6 | 6.0 | 100 | 51.1 | 3.2 | ||||||
200 | 156.2 | – | 200 | 83.5 | – | ||||||
18 | 0.3 | 50 | 39.5 | 32.5 | 30.5 | – | 50 | 25.8 | 22.8 | 21 | – |
100 | 69.6 | 4.0 | 100 | 44.0 | 2.6 | ||||||
200 | 122.9 | – | 200 | 81.9 | – | ||||||
24 | 0.3 | 50 | 41.9 | 31.7 | – | – | 50 | 23.5 | 21.5 | – | – |
100 | 68.2 | – | 100 | 40.8 | – | ||||||
200 | 117.4 | – | 200 | 76.9 | - | ||||||
12 | 0.1 | 50 | 40.2 | 27.0 | – | – | 50 | 22.2 | 20.4 | – | – |
100 | 52.8 | – | 100 | 38.9 | – | ||||||
200 | 97.4 | – | 200 | 72.8 | – | ||||||
12 | 0.72 | 50 | 67.3 | 46.7 | 45 | – | 50 | 29.2 | 26.0 | 24 | – |
100 | 119.9 | 8.8 | 100 | 57.9 | 4.0 | ||||||
200 | 202.4 | – | 200 | 92.1 | – | ||||||
L [mm] | H [mm] | (b) Caudal → Cranial | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Caudal first shearing | Cranial second shearing | ||||||||||
σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ϕres [°] | Ψ [°] | σ′v [kPa] | τpeak [kPa] | ϕpeak [°] | ϕres [°] | Ψ [°] | ||
6 | 0.3 | 50 | 26.9 | 24.3 | 21.7 | – | 50 | 58.1 | 43.1 | 40.1 | – |
100 | 49.5 | 3.5 | 100 | 105.7 | 7.2 | ||||||
200 | 86.9 | – | 200 | 178.5 | – | ||||||
12 | 0.3 | 50 | 24.4 | 22.9 | 19.7 | – | 50 | 49.9 | 38.3 | 36.5 | – |
100 | 46.6 | 3.4 | 100 | 84.6 | 5.3 | ||||||
200 | 81.2 | – | 200 | 152.7 | – | ||||||
18 | 0.3 | 50 | 26.8 | 22.6 | 18.4 | – | 50 | 45.3 | 33.1 | 30.2 | – |
100 | 43.6 | 2.8 | 100 | 76.5 | 3.7 | ||||||
200 | 80.9 | – | 200 | 121.8 | – | ||||||
24 | 0.3 | 50 | 23.2 | 21.4 | – | – | 50 | 38.3 | 29.4 | – | – |
100 | 39.5 | – | 100 | 68.8 | – | ||||||
200 | 77.5 | – | 200 | 104.3 | – | ||||||
12 | 0.1 | 50 | 22.9 | 21.6 | – | – | 50 | 35.7 | 26.3 | – | – |
100 | 41.8 | – | 100 | 51.6 | – | ||||||
200 | 77.2 | – | 200 | 95.2 | – | ||||||
12 | 0.72 | 50 | 28.6 | 26.3 | 22 | – | 50 | 64.3 | 46.3 | 43.9 | – |
100 | 53.1 | 3.8 | 100 | 118.8 | 7.4 | ||||||
200 | 95.8 | – | 200 | 199.5 | – | ||||||
Untextured | 50 | 16.5 | 18.4 | – | – | – | – | – | – | – | |
100 | 33.5 | – | – | – | – | ||||||
200 | 66.4 | – | – | – | – | ||||||
