ABSTRACT
The construction of underground structures inevitably results in the unloading of stresses in certain areas of the ground. In the presence of fine soils susceptible to swelling by hydration, this unloading can cause a swelling phenomenon. The stresses generated by this swelling phenomenon can be very high and must be taken into account from the earliest design phases to ensure the structure’s durability and proper operation during the service phases. The particularity of the grey molasse of Lausanne is linked to the way it was deposited during its formation. Some of the “lenses” are marly and have shown a significant swelling potential. As part of the design of a railway tunnel on the suburban zone of Lausanne, different approaches of soil-structure interaction using finite elements calculations were considered in the design of these structures.
