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The Scientific World Journal
Volume 2015, Article ID 237930, 13 pages
http://dx.doi.org/10.1155/2015/237930
Research Article

Assessment of the Efficiency of Consolidation Treatment through Injections of Expanding Resins by Geotechnical Tests and 3D Electrical Resistivity Tomography

1Department of Earth Sciences “Ardito Desio”, University of Milan, Via Mangiagalli 34, 20133 Milan, Italy
2Geosec S.r.l., Via G. di Vittorio 41/b, 43044 Collecchio, Italy
3Geostudi Astier S.r.l., Via A. Nicolodi 48, 57121 Livorno, Italy
4Department of Civil Engineering, Environmental Engineering and Architecture, Via Marengo 2, 09123 Cagliari, Italy
5Department of Physic and Earth Sciences, Via Saragat 1, 44122 Ferrara, Italy

Received 20 December 2014; Accepted 13 May 2015

Academic Editor: Ahmed El-Shafie

Copyright © 2015 T. Apuani et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The design and execution of consolidation treatment of settled foundations by means of injection of polyurethane expanding resins require a proper investigation of the state of the foundation soil, in order to better identify anomalies responsible for the instability. To monitor the injection process, a procedure has been developed, which involves, in combination with traditional geotechnical tests, the application of a noninvasive, geophysical technique based on the electrical resistivity, which is strongly sensitive to presence of water or voids. Three-dimensional electrical resistivity tomography is a useful tool to produce effective 3D images of the foundation soils before, during, and after the injections. The achieved information allows designing the consolidation scheme and monitoring its effects on the treated volumes in real time. To better understand the complex processes induced by the treatment and to learn how variations of resistivity accompany increase of stiffness, an experiment was carried out in a full-scale test site. Injections of polyurethane expanding resin were performed as in real worksite conditions. Results confirm that the experimented approach by means of 3D resistivity imaging allows a reliable procedure of consolidation, and geotechnical tests demonstrate the increase of mechanical stiffness.