ABSTRACT
The paper describes relevant design aspects for the realization of the southern portion of Line 15, structure that represents a part of Grand Paris Express Project in the surroundings of Villiers Sur Marne. The lot includes two double-track circular single tunnels (main line and SMR stretch), a large one excavated with conventional method, underground stations, shafts and connecting passages. The line tunnels, 8.70 m in (internal) diameter, are realized by using EPB TBMs, with the contemporary disposition of a precast lining composed by 5+1 r. c. segments. The focus of the contribution is mainly related to the studies carried out to define advancing procedures in terms of head pressures, back-filling pressures, and to estimate the expected settlements. Thresholds for particular crossings in correspondence of low covers, buildings, interferences etc. are presented and discussed, also with a strong link to numerical studies; the approaches followed for the definition of alert and alarm situations are also presented.
Technological aspects and solutions are then described, summarizing the impact of the works in terms of surface settlements based on monitoring system feedback.
