Details/description:
CLIENT: Tuscany Regional Authorities – project for the safety management of the existing urban residential context on the hills next to the FI-PI-LI expressway.
USE: Residential Buildings.
CONFIGURATION OF THE DAMAGE: significant extensive cracks due to differential subsidence at the corners of the building.
LITHOLOGICAL CONTEXT: surface filling materials, clay.
FOUNDATION STRUCTURE: direct continuous foundation (built in the early '70s).
EXTENT OF PROCEDURE: approx. 20 lm of foundation.
DIAGNOSTIC SYSTEM: analysis of the loads (P,Q,Con,Dis), survey of the crack pattern, static penetrometric tests, 3D ERT dipole-dipole array48, in multi-station mode.
DIAGNOSTIC CRITERIA: overlapping analysis of all the data measured.
DESCRIPTION OF PROCEDURE: First we performed a geophysical 3D ERT underneath the footprint of each of the small buildings in order to get a clearer picture of the resistive distributions of the masses of soil underneath so as to be able to identify the portions of ground within the load-bearing mass area deemed anomalous and non homogeneous compared to the general context and to the areas not affected by the subsidence.
We then proceeded to prepare injection pipes especially designed to convey significant reducing or eliminating effects of the anomalies detected towards the largest non homogeneous masses subject to subsidence. The injections were carried out between the foundation curb and the ground, taking care to compress the foundation ground in order to obtain an appreciable reduction and removal of the interstitial water.
In fact, following the injection of the slow expansion resin, considerable increases in the electrical resistivity values were observed and peaks exceeding even 40% were measured, that were present up to a height of 4.00 m from ground level.
