Tunnel monitoring
1 Monitoring content
The main monitoring contents are as follows:
Ø and description of surrounding rock and support status
Ø subsidence
Ø Tunnel vault settlement
Ø Tunnel convergence monitoring
Ø Monitoring of inclination of nearby buildings
Ø Pore water pressure monitoring
Ø Supporting earth pressure monitoring
Ø Monitoring of vertical displacement of soil
Ø Monitoring of soil horizontal displacement
2 Monitoring programs
The schematic diagram of the monitoring plan is as follows: 
The specific monitoring plan is as follows:
|
Monitoring item |
sensor |
Measuring point layout |
|
Surface subsidence displacement of the shallow buried section of the tunnel |
level |
Opening section, shallow buried section |
|
Clearance Convergence Monitoring |
Laser rangefinder |
One section every 5-50m , 2-3 pairs of measuring points per section |
|
Vault subsidence monitoring |
Laser rangefinder |
One section every 5-50m , 2-3 pairs of measuring points per section |
|
Bolt axial force monitoring |
Rebar gauge |
1-2 sections per representative section, 5 anchors per section, 2 measuring points per anchor |
|
Contact pressure monitoring between surrounding rock and primary branch |
earth pressure box |
1 section per representative section, 5 measuring points per section |
|
Steel Support Stress Monitoring |
Surface strain gauge |
1 section per representative section, 5 measuring points of steel support internal force per section |
|
Initial lining stress monitoring |
Buried strain gauge |
1 section per representative lot , 5 measuring points per section |
|
Secondary lining stress monitoring |
Buried strain gauge |
1 section per representative lot , 5 measuring points per section |
|
Seepage pressure monitoring |
Pore pressure gauge |
1 section per representative lot , 5 measuring points per section |
3 system advantages
Ø 24 -hour real-time monitoring: Automatic online monitoring of bridge deformation, force, environment, etc., and real-time grasp of the safety status of the overall construction / operation of the bridge.
Ø -level early warning: When the data is abnormal, the system will trigger the corresponding three-level alarm mechanism, and notify users in the form of SMS, fax, broadcast, etc. at the first time.
Ø Emergency plan handling: directly extract the corresponding handling methods from the expert database, and take measures such as personnel intervention and road blockade in a timely manner to eliminate potential safety hazards in the bud.
Ø Research on structural damage mechanism: macroscopic analysis of structural damage mechanism, structural deformation and damage trend research, induction and deduction.
Ø reference basis: The storage of monitoring data provides an analogy basis for the design and construction of similar projects in the future.
Ø Formation of industry norms and standards: formulate a safety evaluation standard system suitable for structural health monitoring, and form industry standards and norms.
4 Monitoring basis
1) Project-related survey and design materials and bidding documents;
2) "Technical Regulations for Monitoring and Measurement of Railway Tunnels";
3) "Code for Design of Highway Tunnels" ( JTJ D70-2004 );
4) "Technical Specification for Highway Tunnel Construction" ( JTG F60-2009 );
5) "Technical Rules for Highway Tunnel Construction" ( JTG/T F60-2009 );
6) "Technical Specification for Bolt Shotcrete Support" ( GB 50086-2001 ) ;
7) "Urban Rail Transit Engineering Measurement Specification" ( GB50308-2008 );
8) "Technical Specifications for Urban Rail Transit Engineering Monitoring" ( GB 50911-2013 );
9) "Urban Measurement Specification" ( CJJ/T8-2011 );
10) "Engineering Measurement Specification" ( GB50026-2007 );
11) "National First- and Second-Class Leveling Specifications" ( GB/T12897-2006 );
12) "Detailed Rules for Safety and Quality Management of Construction Division";
13) The owner provides relevant engineering data of the tunnel;
14) Various technical standards and relevant laws and regulations issued by the state and the Ministry of Transport, such as current norms, regulations, inspection standards, etc.