Table 1:
Basic information of the datasets and projects (Liu et al. 2019, 2020)
| Data sources | YS | YH | ZJ | HZ | QD | |||
|---|---|---|---|---|---|---|---|---|
| Area I | Area II | Area I | Area II | Area I | Area II | |||
| Number of samples [-] | 460 | 80 | 50 | 230 | 46 | 250 | 56 | 100 |
| TBM type [-] | Open type | Double-shield | Double-shield | Double-shield | Double-shield | |||
| Number of tunneling variables [-] | 178 | 202 | 276 | 276 | 202 | |||
| TBM diameter [m] | 7.9 | 7.0 | 6.2 | 6.0 | 7.0 | |||
| Number of cutters [-] | 56 | 48 | 42 | 40 | 48 | |||

Figure 1:
Division of the field datasets

Figure 2:
Part of the covariance matrix results

Figure 3:
Part of the covariance matrix results
Table 2:
Mean absolute percentage error of the sub-models in the 10-fold-corss-validation
| Order | Training sub-set | Test sub-set | BPNN | SVR | RF | |||
|---|---|---|---|---|---|---|---|---|
| UCS [%] | Jf [%] | UCS [%] | Jf [%] | UCS [%] | Jf [%] | |||
| 1 | 2–10 | 1 | 9.7 | 8.4 | 9.2 | 9.2 | 9.0 | 8.9 |
| 2 | 1, 3–10 | 2 | 8.6 | 8.2 | 9.1 | 8.3 | 8.9 | 8.8 |
| 3 | 1–2, 4–10 | 3 | 9.0 | 9.4 | 8.5 | 8.6 | 8.7 | 9.0 |
| 4 | 1–3, 5–10 | 4 | 9.6 | 9.2 | 9.9 | 9.6 | 8.8 | 9.8 |
| 5 | 1–4, 6–10 | 5 | 10.0 | 9.7 | 8.8 | 9.2 | 10.1 | 9.1 |
| 6 | 1–5, 7–10 | 6 | 8.4 | 8.7 | 9.2 | 8.3 | 8.9 | 10.1 |
| 7 | 1–6, 8–10 | 7 | 9.7 | 8.9 | 9.5 | 9.6 | 9.4 | 8.8 |
| 8 | 1–7, 9–10 | 8 | 9.3 | 9.5 | 8.9 | 8.7 | 10.6 | 9.4 |
| 9 | 1–8, 10 | 9 | 9.7 | 9.4 | 9.2 | 9.8 | 9.1 | 8.9 |
| 10 | 1–9 | 10 | 9.4 | 8.9 | 9.2 | 9.2 | 9.3 | 8.8 |

Figure 4:
Eigenvalues and the accumulated information of the top 10 variable in the four projects

Figure 5:
Comparison between the predict UCS to the actual values in different project

Figure 6:
Comparison between the predict Jf to the actual values in different project

Figure 7:
Predicted results of UCS in test sets

Figure 8:
Predicted results of Jf in test sets

Figure 9:
Comparison between the predicted UCS and Jf by SVR, RF, and the actual values in validation sets
Table 3:
Predicted MAPE values of the validation sets in other four projects
| Projects | UCS | Jf | ||||
|---|---|---|---|---|---|---|
| BPNN [%] | SVR [%] | RF [%] | BPNN [%] | SVR [%] | RF [%] | |
| YS | 10.1 | 10.3 | 10.7 | 8.4 | 8.5 | 8.8 |
| ZJ | 11.0 | 11.5 | 11.4 | 8.8 | 9.4 | 9.1 |
| YH | 8.1 | 8.3 | 9.0 | 5.3 | 6.0 | 6.2 |
| HZ | 9.7 | 8.9 | 9.6 | 9.1 | 8.8 | 9.9 |
| QD | 10.5 | 10.2 | 10.8 | 9.7 | 8.9 | 10.4 |
| Average value | 9.9 | 9.8 | 10.3 | 8.3 | 8.3 | 8.9 |

Figure 10:
Comparison between the predicted UCS and Jf by SVR, RF, and the actual values in test sets
Table 4:
Predicted MAPE values of the test sets in other four projects
| Projects | UCS | Jf | ||||
|---|---|---|---|---|---|---|
| BPNN [%] | SVR [%] | RF [%] | BPNN [%] | SVR [%] | RF [%] | |
| YS | 13.0 | 12.8 | 14.4 | 12.7 | 13.2 | 14.8 |
| ZJ | 11.9 | 12.2 | 13.9 | 12.3 | 11.8 | 14.2 |
| HZ | 11.9 | 12.3 | 13.2 | 11.0 | 11.2 | 13.5 |
| Average value | 12.3 | 12.5 | 13.8 | 12.0 | 12.1 | 14.2 |
Table 5:
The network structures and time costs of PCA and FV models
| PCA model | FV models | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| YS | YH | ZJ | HZ | QD | YS | YH | ZJ | HZ | QD | ||
| Number of input neurons [-] | 5 | 4 | 3 | 4 | 4 | 178 | 202 | 276 | 276 | 202 | |
| Number of hidden neurons [-] | 8 | 6 | 5 | 6 | 6 | 56 | 64 | 72 | 72 | 64 | |
| Time costs [s] | UCS | 6 | 4 | 4 | 4 | 4 | 202 | 179 | 261 | 252 | 188 |
| Jf | 6 | 4 | 3 | 5 | 3 | 196 | 165 | 249 | 266 | 193 | |

Figure 11:
Comparison between the calculating accuracy in validation sets of PCA model and FV models

Figure 12:
Comparison between the calculating accuracy in test sets of PCA model and FV models

