Method for increasing the strength of a volume of soil, particularly for containing and supporting excavation faces

Abstract

A method for increasing the strength of a volume of soil, particularly for containing and supporting excavation faces, which comprises at least one reinforcement step that consists in producing a plurality of mutually spaced reinforcement holes arranged substantially vertically or inclined with respect to a vertical direction in the volume of soil to be strengthened; reinforcement elements are then inserted in the reinforcement holes and are locked within the soil by injecting in the reinforcement holes a synthetic locking substance that expands by chemical reaction. The method can optionally also comprise a step for consolidation of the volume of soil by injecting, in injection holes that are arranged vertically or are inclined with respect to the vertical and are formed beforehand in the soil, a synthetic consolidation substance that expands by chemical reaction.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for increasing the strength of a volume of soil, particularly for containing and supporting excavation faces. More particularly, the method according to the present invention allows to contain and support in a vertical position, or in a position that is slightly inclined with respect to the vertical, an excavation face or otherwise a mass of soil, improving resistance to all the various stresses of a portion (or band) of said soil that is interposed between the excavated volume and the volume of natural soil left in place. BACKGROUND ART [0002] More generally, the method according to the invention can be used to constitute a portion (or band) of improved and reinforced soil within a volume of soil, for example in order to stabilize or increase the stability safety of a slope, of a vault of a tunnel or of any other situation in which a volume of soil, due to the force of gravity or to other forces, tends to undergo defo...

AI Technical Summary

Benefits of technology

[0039] The aim of the present invention is to provide a method for increasing the resistance to all the various stresses of a portion (or band) of soil, particularly for containing and supporting excavation faces, that is capable of solving the problems noted above with reference to known types of method.

[0040] Within this aim, an object of the invention is to provide a method that allows to increase satisfactorily the resistance to all the various stresses of a portion (or band) of soil with distinctly lower costs than those required by known types of method.

[0041] Another object of the invention is to provide a method that can be performed in a short time and with compact equipment.

[0042] Another object of the invention is to provide a method that can be performed in absolute safety even in the immediate vicinity of dwellings and even if the space available is limited.

Problems solved by technology

Since granule size in cohesive soils is very small, drained conditions occur a very long time after excavation, since all the water contained between the grains has to flow out.

In a different field, the problem of instability of a slope that is not necessarily steeply inclined may occur.

The volume of soil that lies above said surface, due to its own weight, in fact tends to break the deep soil, inducing horizontal displacements that are dangerous for buildings arranged at the surface.

In other cases, the problem of instability of a vault in a tunnel may occur (FIG. 4).

Performing an excavation, albeit one having a circular cross-section, can induce in the volume of soil that lies above the vault strong tangential tensions that can cause the collapse of the overlying soil (sinkhole).

Both of these technologies, in addition to being highly invasive, since they require the use of very large machines, require very long times and entail very high costs.

This method, sometimes very risky and in any case scarcely applied, does not allow to use completely the excavated volume, since said volume is occupied by the supporting structures.

This method sometimes cannot be applied, since the machines required for the installation are large and the vibrations produced during driving can damage nearby buildings.

However, in the time interval between execution of the excavation and nail driving, an unexpected instability may occur which can lead to the collapse of the face or of part of said face.

In general, in any case, this method, known as “soil nailing”, entails the use of large machines and high installation costs.

These pressures may cause migration of the injected cement mixture into volumes of soil that are distant from the intended ones, causing considerable damage to nearby buildings.

These characteristics, together with high installation costs, limit considerably the application of this method in the urban environment.

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