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Details of centrifuge tests (prototype scale), Logagnathan et al_ (2000)_
| Test No. | Tunnel depth, H: m | |
|---|---|---|
| 1 | Pile length, Lp = 18 m Pile diameter, d= 0.8 m | 15 |
| 2 | EI= 1400 MN m2 Tunnel diameter, D= 6 m Stiff kaolin clay, ~75 kPa | 18 |
| 3 | 21 |
Analysis series for a single and group of piles with different offset ratio (E/D)
| Single pile | Pile group (3×3) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Analysis series | I | II | III | IV | V | VI | VII | VIII | IX | X |
| C/D | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 |
| E/D | 0 | 0.5 | 1.0 | 1.5 | 2.0 | 0 | 0.5 | 1.0 | 1.5 | 2.0 |
Soil parameters adopted in the numerical analysis (from Miro et al_ 2012)_
| Soil Parameters HS model | ||
|---|---|---|
| Parameters | values | units |
| Friction angle, φ | 35 | |
| Dilatancy angle, Ψ | 5 | |
| Cohesion, c | 10 | [kN/m2] |
| Secant stiffness in the standard drained triaxial test, | 35000 | [kN/m2] |
| Tangent stiffness for primary oedometer loading, | 35000 | [kN/m2] |
| Unloading and reloading stiffness, | 100000 | [kN/m2] |
| Reference pressure, pref | 100 | [kN/m2] |
| Power for stress-level dependency of stiffness, m | 0.7 | [-] |
| Failure ratio, Rf | 0.9 | [-] |
| Poisson’s ratio for unloading-reloading,Ѵur | 0.2 | [-] |
| Soil weight above phreatic level, γunsat | 17 | [kN/m3] |
| Soil weight below phreatic level, γsat | 20 | [kN/m3] |
| Strength reduction factor for interfaces in | 0.6 | [-] |
| PLAXIS, Rinter |
Analysis series for a single and group of piles with different depth ratio (C/D)_
| Soil type | φ (degree) | c (kN/m2) |
|---|---|---|
| 1* | 35 | 10 |
| 2 | 37 | 0 |
| *Soil 1 has the same parameters as the soil used in (Table 2) | ||
Concrete parameters adopted in the numerical analysis_
| Parameters | Values | Units | Model | |||
|---|---|---|---|---|---|---|
| Pile | Pile cap | Tunnel lining | TBM shield | |||
| Diameter (D) | 1 | - | - | - | m | Linear |
| Thickness (t) | - | 1 | 0.25 | 0.35 | m | elastic |
| Elasticity modulus (E) | 30×106 | 30×106 | 30×106 | 210×106 | ||
| Unit weight (γ) | 25 | 25 | 25 | 38 | ||
| Possion’s ratio (ѵ) | 0.2 | 0.2 | 0.2 | 0.3 | - | |