Analysis of excavations in complex urban areas
The design of underground structures in urban areas, typically with low overburden, the interference between excavations and existing structures must be determined with respect to stresses and induced settlements. Given the considerable density of underground structures already built in large metropolitan centers, new structures often fit into a complex infrastructures framework.
The analysis of interferences between excavations and existing structures under complex design conditions requires advanced numerical studies. Lombardi Ltd. provides services in this field using commercial 2D and 2D software. Lombardi’s experience has been gained by working on very complex design cases that required the implementation of advanced constitutive links and the development of specific calculation methods to manage design solutions in detail within large three-dimensional numerical models.
An important study concerned the design of a vertical access shaft built in an urban environment with nearby historic buildings on the surface and close to a subway line with masonry lining. The three-dimensional modeling of the shaft allowed to optimize the excavation method and the dimensioning of the supports, so that the subsidence induced on the surface and on the existing line respected the contractual limits.
In this context of underground stations, particularly noteworthy is the project of an underground interconnection station in the 8th arrondissement of Paris. The cavern is located at the intersection of existing underground structures, which cross at three different levels, requiring three-dimensional numerical modeling. The evaluation of the interference between excavations and existing structures was possible – in a large-scale model – by applying a calculation method allowing to relate the design details of excavation and support to the settlement containment strategy.
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Civil designs; Consultancy; Special studies