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

Apuani T, Giani GP, d'Attoli M, Fischanger F, Morelli G, Ranieri G, Santarato G - ScientificWorldJournal (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences "Ardito Desio", University of Milan, Via Mangiagalli 34, 20133 Milan, Italy.

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.

No MeSH data available.


Related in: MedlinePlus

Effects of resin treatment: propagation of resins in clayey soils (a) main conduits along preexisting preferential weakness channels; (b) induced fracturing and spreading on a horizontal plane; (c) dendritic network at millimetric scale.
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fig7: Effects of resin treatment: propagation of resins in clayey soils (a) main conduits along preexisting preferential weakness channels; (b) induced fracturing and spreading on a horizontal plane; (c) dendritic network at millimetric scale.

Mentions: Based on these considerations, ERT, as an indirect noninvasive technique, is ideal for monitoring the injection treatment while it is being carried out. The mechanism by means of which the polyurethane resins (which have high electrical resistivity) are distributed in the soil normally follows a dendritic pattern (see Figure 7). Therefore the filaments of resin do not have any significant impact on the flow of electrical current in the subsurface; as a consequence the resistivity variations, observed along time while injections are carried out, are to be attributed to the effect of the removal of the interstitial water and/or the filling of voids, as a result of the compaction triggered by the expansion of the resin.


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

Apuani T, Giani GP, d'Attoli M, Fischanger F, Morelli G, Ranieri G, Santarato G - ScientificWorldJournal (2015)

Effects of resin treatment: propagation of resins in clayey soils (a) main conduits along preexisting preferential weakness channels; (b) induced fracturing and spreading on a horizontal plane; (c) dendritic network at millimetric scale.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4488174&req=5

fig7: Effects of resin treatment: propagation of resins in clayey soils (a) main conduits along preexisting preferential weakness channels; (b) induced fracturing and spreading on a horizontal plane; (c) dendritic network at millimetric scale.
Mentions: Based on these considerations, ERT, as an indirect noninvasive technique, is ideal for monitoring the injection treatment while it is being carried out. The mechanism by means of which the polyurethane resins (which have high electrical resistivity) are distributed in the soil normally follows a dendritic pattern (see Figure 7). Therefore the filaments of resin do not have any significant impact on the flow of electrical current in the subsurface; as a consequence the resistivity variations, observed along time while injections are carried out, are to be attributed to the effect of the removal of the interstitial water and/or the filling of voids, as a result of the compaction triggered by the expansion of the resin.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences "Ardito Desio", University of Milan, Via Mangiagalli 34, 20133 Milan, Italy.

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.

No MeSH data available.


Related in: MedlinePlus