ABSTRACT
The Line E of the express regional railway Paris network (RER) is being extended westward to improve service to La Défense business district and western suburbs of Paris. This paper concentrates on the western chamber of the existing underground station of Haussmann-Saint-Lazare, a connection structure between the tunnel boring machine (TBM) tunnel and the existing station. Constructed using conventional method, in a very urbanized and sensitive environment, spanning 180 meters with an irregular geometry, the western chamber is where the TBM completes its journey. The construction works, carried out between 2019-2021, took place in a variable geology and under the water table, brought down by widespread pumping to allow a safe excavation. This paper outlines the geological, hydrogeological and geotechnical conditions in the sector, highlighting its environment complexity. It details the challenges faced and strategies used to minimize risks to neighboring structures, focusing on design-phase calculations and construction methods choices.
