Method for consolidating foundation soils or for lifting very heavy or very large structures requiring the application of a pressure of more than 500 kpa

Abstract

A method for consolidating foundation soils or for lifting very heavy or very large structures requiring the application of a pressure of more than 500 kPa, which consists in injecting into the soil to be consolidated or into the soil below the foundations of the structure to be lifted substances which expand as a consequence of a chemical reaction and are suitable to generate, during expansion, a pressure of more than 500 kPa.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a method for consolidating foundation soils or for lifting very heavy or large structures requiring the application of a pressure of more than 500 kPa. [0002] In the field of interventions for consolidating foundation soils for buildings, aimed at increasing the bearing capacity of the soil before and after building a structure, and in the field of interventions for obviating the subsidence of flooring or paving, it is known to use substances which expand as a consequence of a chemical reaction, of the type comprising a mixture of polyols and an MDI isocyanate, or a similar expandable substance, which after expansion solidifies and makes said expansion permanent. [0003] European Patent no. 851,064 by same Applicant discloses a method for increasing the bearing capacity of foundation soils that substantially consists in forming a plurality of spaced deep holes in the soil and in injecting through these holes an expan...

AI Technical Summary

Benefits of technology

[0014] The aim of the present invention is to provide a method that allows to utilize the force generated by the expansion of these substances to consolidate foundation soils and to lift, particularly for repair after subsidence, very large or very heavy structures, such as for example skyscrapers, large monumental buildings, bridges, highway structures, silos, dams, large infrastructures etcetera, which can be lifted only by overcoming a pressure thereof on the soil of far more than 500 kPa, i.e., for interventions that up to now were not even imaginable by using substances that expand as a consequence of a chemical reaction, or in any case to obtain effects of overconsolidation in some kinds of soil underlying even not very heavy structures, since sometimes this is the only way to prevent subsidences and ensure, over time, the stability of the structure.

[0015] Within this aim, an object of the present invention is to provide a method that allows to perform prevention or repair after subsidences of very large or very heavy structures with considerably lower costs than required by known kinds of intervention.

Problems solved by technology

For this reason, this method has never been deemed suitable and used to perform consolidation of foundations of very large or very heavy buildings or structures or to try to lift such structures, since they generally apply to the soil a pressure of more than 500 kPa; this happens because it was thought that the expansion of said substances under said structures would not be able to improve soil compaction or produce lifting of the structure.

Moreover, no attempt was made to further consolidate soils that were already well-compacted and offered a breaking strength of more than 500 kPa.

Actually, relatively light structures often subside although being built on soils with a capacity that exceeds the overlying load.

This occurs simply because a consolidation process is in progress which causes a reduction in volume, with consequent subsidence over time due to water migration.

However, for existing structures, where this was not done or where the expected extent of the subsidence turns out to be incorrect, in view of the extreme difficulty of formulating exact subsidence predictions, even with in-depth geotechnical studies, or also where it is important to prevent from the start the onset of these subsidences, in order to prevent for example even minimal level oscillations of instruments or machines, it is necessary to intervene to remedy or prevent the phenomenon, since a large increase in the compression of the soil (even much higher than the compression required for bearing capacity alone) leads to the development of consolidation and therefore prevents subsidence.

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