AT – Pipe Umbrella System with innovative Squeezed Connection stabilizes the Advancement of Metro Line 4 in Paris
Line 4 is one of the 16 lines of the Paris metro system that currently connects Porte de Clignancourt in the north of the city with Mairie de Montrouge in the south. The line crosses the center of Paris and is connected to important regional train stations. Currently, Line 4 is one of the most used lines in the entire subway system. After the opening of the current last stop, Mairie de Montrouge, Line 4 will be extended for about 1.9km towards the south with the two new stations Verdun-Sud and Bagneux.
Verdun-Sud will have a double track configuration and Bagneux will have a three-track layout. Furthermore, Bagneux will be connected to Line 15, the Red Line.
This project can be considered a trial project for the global Grand Paris Express, where occupational safety will be a major consideration. Excavation was carried out in limited space conditions. In addition, the ground was difficult, and the urban environment required special care regarding stability and the limitation of possible surfac settlements.
The AT – Pipe Umbrella System was used as a pre-support system in ground conditions prone to settlements in the future station areas; it was supplied by DSI Underground Austria in cooperation with ROBODRILL. Four AT – 114 Pipe Umbrellas (114.3mm x 6.3mm) with squeezed connections and the AT – Automation Unit were used.
The fast and safe implementation of the pipe umbrella installation was ensured by the special ALWAG Systems squeezed pipe connection. Installation of the pipe umbrella system was carried out using air flushing.
The customized ROBODRILL jumbo was perfectly adapted to the AT – Automation Unit for creating the squeezed connection and to the AT – Pipe Umbrella Support System. In the course of first-time installation, technical support was provided by a DSI Underground Austria team on site.
The average production time in challenging ground conditions was 8 15m long tubes in 10 hours.