Shield tunnel construction is one of the main methods for urban underground engineering. During shield advancement, the excavation face disturbs the surrounding soil, causing ground settlement, building deformation, and underground pipeline displacement. Monitoring work is an important means to ensure construction safety and protect surrounding environments.
This scenario solution applies to shield tunnel monitoring projects with the following conditions:
- Shield Diameter: 4m-15m (various diameters)
- Geological Conditions: Clay, silt, sand, gravel, and composite strata
- Surrounding Environment: Urban areas with dense buildings, underground pipelines, and traffic
- Crossing Conditions: Crossing rivers, railways, subways, buildings, and other sensitive targets
| Challenge Category |
Description |
Response Strategy |
| Settlement Control |
Shield advancement causes ground settlement, requiring strict control |
Real-time monitoring, parameter optimization |
| Sensitive Crossing |
Crossing subways, buildings, and other sensitive targets |
Encrypted monitoring, parameter control |
| Real-time Requirements |
Need to grasp deformation in real-time during advancement |
Automated monitoring, real-time feedback |
| Multi-parameter Analysis |
Need to correlate shield parameters with monitoring data |
Data fusion analysis, intelligent early warning |
| Long-term Stability |
Settlement continues to develop after advancement |
Extended monitoring period, trend prediction |
The overall objective of shield tunnel monitoring is to: through systematic monitoring, real-time grasp of ground settlement, building deformation, and tunnel convergence during shield advancement, timely detection of abnormal changes and early warning, provide data support for shield parameter optimization, and ensure construction safety and environmental protection.
| Monitoring Item |
Monitoring Content |
Common Instruments |
Precision Requirement |
| Surface settlement |
Vertical displacement of ground surface |
Total station, level |
±1.0mm |
| Deep settlement |
Settlement at different depths |
Layered settlement gauge |
±1.0mm |
| Soil horizontal displacement |
Horizontal displacement of soil |
Inclinometer |
±0.1mm/500mm |
| Monitoring Item |
Monitoring Content |
Common Instruments |
Precision Requirement |
| Tunnel convergence |
Change in tunnel diameter |
Convergence gauge, total station |
±0.5mm |
| Segment deformation |
Deformation of tunnel segments |
Convergence gauge |
±0.5mm |
| Segment joint opening |
Opening of segment joints |
Joint gauge |
±0.1mm |
| Monitoring Item |
Monitoring Content |
Common Instruments |
Precision Requirement |
| Building settlement |
Settlement of adjacent buildings |
Total station, level |
±0.5mm |
| Building inclination |
Inclination of adjacent buildings |
Total station |
±1/10000 |
| Building cracks |
Width of building cracks |
Crack gauge |
±0.01mm |
| Pipeline settlement |
Settlement of underground pipelines |
Total station, level |
±1.0mm |
| Location |
Spacing |
Points per Section |
Layout Range |
| Normal section |
10m |
7-9 |
2-3 times tunnel diameter |
| Building section |
5m |
9-11 |
2-3 times tunnel diameter |
| Sensitive section |
3m |
11-13 |
2-3 times tunnel diameter |
| Location |
Spacing |
Points per Section |
| Normal section |
10 rings |
5-7 |
| Sensitive section |
5 rings |
7-9 |
| Construction Stage |
Monitoring Frequency |
Basis |
| Advancement preparation |
1 time/day |
Before advancement |
| Normal advancement |
2 times/day |
During advancement |
| Sensitive crossing |
4 times/day or real-time |
Critical period |
| After advancement |
1 time/day |
Development period |
| Stable period |
1 time/week |
Stable period |
| Parameter |
Normal Range |
Sensitive Range |
Control Basis |
| Earth chamber pressure |
100-180 kPa |
140-170 kPa |
Geological conditions |
| Advancement speed |
10-60 mm/min |
20-30 mm/min |
Sensitive crossing |
| Cutter torque |
500-1800 kN·m |
1000-1500 kN·m |
Geological conditions |
| Synchronous grouting |
4.0-7.0 m³/ring |
5.0-6.0 m³/ring |
Settlement control |
| Monitoring Indicator |
Parameter Adjustment |
Adjustment Direction |
| Settlement too large |
Increase earth chamber pressure |
Increase |
| Settlement too fast |
Decrease advancement speed |
Decrease |
| Settlement rate high |
Increase synchronous grouting |
Increase |
| Convergence large |
Optimize grouting pressure |
Optimize |
| Warning Level |
Trigger Condition |
Response Measures |
| Blue |
Settlement reaches 50% of control value |
Strengthen monitoring |
| Yellow |
Settlement reaches 70% of control value |
Encrypt monitoring, adjust parameters |
| Orange |
Settlement reaches 85% of control value |
Start emergency plan, prepare grouting |
| Red |
Settlement reaches 100% of control value |
Stop advancement, start emergency rescue |
The following values are typical values for reference. Actual control values should be determined based on design requirements and specific project conditions.
| Monitoring Item |
Control Value (mm) |
Warning Value (mm) |
| Surface settlement (normal) |
30 |
20 |
| Surface settlement (building) |
20 |
15 |
| Surface settlement (subway) |
10 |
8 |
| Tunnel convergence |
15 |
10 |
| Building settlement |
20 |
15 |
| Building inclination |
1/500 |
1/700 |
| Pipeline settlement |
15 |
10 |
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