Grand Paris Express – Line 18 OA1 | France

Project summary

Service provided:  Monitoring during construction of an access shaft for the future line 18 at Orly airport
Location:  Paris, France
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Client:  Société du Grand Paris – Chantiers Modernes Construction
Period of the service:  2018 - 2019
Duration of service:  One year and four months

Images of the project

A major project

The future line 18 of the Grand Paris Express stretches approximately 35km from Versailles Chantiers station to Aéroport d’Orly station, where a connection with the southern extension of line 14 is planned. Within Orly airport, the project includes the construction of a circular shaft – called the P01 Orly Sup Annex structure or OA1 – 9m in diameter, 33m deep and created using a diaphragm wall.

During the construction phase, the P01 annex structure will house one of the tunnel boring machines for the tunnel boring work included in work package 1 of Line 18. It also provides emergency access for the tunnel boring work on RATP Line 14 South. This annex structure is located on the axis of the main tunnel of Line 18 and connected by a branch line to the RATP Line 14 tunnel.

During the service phase, the annex structure will provide emergency access to the tunnel for lines 14 and 18 and drainage for the line 18 tunnel. It will also house premises for operation of the line 14 and 18 metro systems.


Monitoring the annex structure for the safety of the worksite and neighbouring areas

The Sixense monitoring teams were appointed to provide and install instrumentation for the OA1 annex structure and nearby buildings located in the geotechnical Influence Zone, in order to measure the impact of the works on neighbouring areas. The testing programme required the installation of a Cyclops for the automated topographic monitoring of building facades and roads, the installation of inclinometers in the walls of the structure and geophones to monitor the vibration impact of the works on surrounding buildings.

All the data was centralised on our Geoscope platform, allowing real-time access to measurements.

Project Key figures

33 deep
9 diameter for the circular shaft
130 prism targets
+60 weeks of continuous topographic monitoring

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