Ground improvement under historical buildings: a case history

The soil improvement technique, used to deepen a large excavation in adherence to an historical building into an urbanized area, will be herein presented. The building suffered relevant damagement yet when any excavation activity had still to be started; thus, the excavation’s sequence and the retain structure had to be redesigned, because the marked sensitivity of the wet sandy-silt soil did not allow any activity in proximity to the building’s foundation. Test pits assessed that soil improvements may be gained by high pressure injections of fast-settling resins, provided that particular executive details would have been respected. The monitoring activities which allowed to recognize the building’s behavior both before, during and after of the close-by excavation process will be resumed too; furthermore, these observations shall be put in comparison with an FEM simulation, which took into consideration all of the excavation sequences, as well as of the soil improvement simulation. Attention will be raised on some relevant details regarding the use of these widely diffused fast-settling resins which, usually, are applied with no particular care and specifications: this common practice is not acceptable in instances like the presented case but, on the contrary, these technologies may really solve difficult problems if they are applied under strict control and specifications.