Vibration monitoring of T2A sector in the Grand Paris express project

Monitoring Summary

Project: Grand Paris, Paris (France)
Sector: T2A, on the metro line 15, between stations Villejuif Louis-Aragon and Créteil l‘Échat
Objective: Vibration monitoring of buildings surrounding the construction sites
Duration: Minimum 4 years
Device type: MR3000C with internal triaxial velocity meter 
Devices installed: 25 (Nov. 2017) year to date
Output: Data transferred to FTP server and automatic alarm notifications via SMS/e-mails when the trigger level is exceeded.

Grand Paris express project - key facts 
City: Paris (France) 
Lines: 2 extended lines, 4 new lines 
New railway lines: 200 km 
New stations: 68 
Passengers/day: 2 million 
Train frequency: 2 to 3 minutes 
Automation: 100% automatic metro system 
Urban impact: 90% of lines will be built underground 
Duration: Until 2030 
Budget: Around 25 billion

Abstract

The Grand Paris Express is a project to extend transportation inside and around Paris (France). The works are focused on: 

• the extension of the current metro lines 11 and 14;
• the construction of 4 new metro lines (15, 16, 17 and 18).

The Grand Paris Express is Europe's largest urban project. The company Sixense Soldata is responsible for the overall monitoring of the T2A sector on the new metro line 15, between the stations Villejuif Louis Aragon and Créteil l’échat. 

The MR3000C instruments made by Syscom are used to monitor vibrations in buildings around construction sites to reduce environmental impact and disturbances. 

25 devices are already installed, and the total expected duration of vibration monitoring is at least 4 years.

Monitoring configuration

The MR3000C used for the structural vibration monitoring has all the following characteristics:

• Internal triaxial velocity meter;
• Embedded 3G modem for internet connection;
• Vertical or horizontal installation, depending on the location;
• External battery pack, in case of main power loss.

The pictures in Figure 3 show some installations of the instruments: on a warehouse (Figure 3a) and inside buildings, on a load-bearing wall (Figure 3b) or at the foundation (Figure 3c).

In Figure 3a-3b the MR3000C is installed vertically, while in Figure 3c it is installed horizontally. In all cases the devices are fixed by using the holes in their mounting plate. 

The MR3000 devices record the following information:

• Event data: the time history of the three components (X, Y, Z) is recorded when the threshold limit of 3 mm/s is exceeded on one of the three axes. The event includes a 1 s pre-event and a 3 s post-event.

• Background data: every minute, the velocity peaks of the three axes are saved in a new file. Each file is 1 hour long, resulting in 24 files per day.

   

Data transfer and analysis

The event and background data are automatically saved in TXT format and sent to Sixense Soldata's secure FTP server. Moreover, e-mails and SMS notifications are sent immediately to the monitoring engineers when a new event is created, informing them of anomalous PPV values and enabling them to reduce work intensity. Figure 4 shows the communication diagram for the Grand Paris Express project.

Figure 5 shows real background data from an MR3000C installed in the T2A sector. The file duration is 1 hour, indicating that the construction works on site end around 17:30. The trigger threshold of 3 mm/s is not exceeded; therefore, no events are created during this period. 

Data in Figure 5 are visualised in the SCS cloud software 

The SCS is used for data visualisation and remote modification of trigger/alarm parameters, as well as for automatically creating PDF reports on recorded data to quickly inform users and authorities about on-site values.

Conclusion

Syscom uses the MR3000C for vibration monitoring in the T2A sector of the Grand Paris, Europe's largest urban project. In November 2017, 25 devices were already installed.

The MR3000C instruments are chosen for their high reliability and embedded communication capabilities. Using the internal 3G modem, they automatically send data to the configured FTP server and send notifications to monitoring engineers if a velocity level is exceeded. Notifications are sent as soon as the event is created to inform users promptly for optimal risk assessment.

The MR3000C units are completely autonomous and independent, making monitoring and management easy and suitable for any vibration monitoring project.

Special thanks to Sixense Soldata for supporting us with this case study. 

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