|
| The target layer | The first-level index layer | The second-level index layer |
|
| The safety risk evaluation for modified shield machine construction applicable to soft soils (U) | The risk of shield launching and receiving (U1) | Deformation of the base (U11) |
| Deviation from the axis during launching (U12) |
| Soil influx into receiving shaft after dismantling portal (U13) |
| Deviation from the axis during receiving (U14) |
| Deformation of support during receiving (U15) |
| The risk of shield tunneling (U2) | Inappropriate tunneling parameters (U21) |
| Excessive rotation of the shield machine (U22) |
| Blockage in earth conveying (U23) |
| Deviation from the designed tunneling (U24) |
| Leakage in the shield sealing system (U25) |
| The risk of segment assembly (U3) | Segment dislocation (U31) |
| Segment deviation (U32) |
| Segment damage (U33) |
| The risk of grouting (U4) | Not grouting in time (U41) |
| Inadequate grouting (U42) |
| Clogging of the grouting pipe (U43) |
| Low quality of the grouting material (U44) |
| The risk of working environment (U5) | Effect of groundwater (U51) |
| The effect of tunnel underneath the river (U52) |
| Tunneling through unfavorable geology (U53) |
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