EP0174253B1 - Slab facing for the slopes of earth fills, for instance earth fills reinforced by means of geotextile layers - Google Patents

Abstract

This invention relates to a facing for the bank of earthen formations, particularly soil masses reinforced by geotextile sheets, said facing being composed of plates individually hooked to the bank by supple hooking elements, and the plates are disposed in substantially horizontal rows, the plates of one row partially overlapping the plates of the row immediately therebeneath.

Description

The invention relates to the finishing of massifs of soil, in particular massifs of reinforced soil.

Soils are low-cost building materials, but with relatively modest mechanical characteristics compared to those of other civil engineering materials, such as steel or concrete, which in turn are much more expensive.

This is the reason why engineers have always sought to raise the mechanical characteristics of soils in order to be able to use them competitively in works or parts of works in which these soils in their natural state, should be rejected.

To achieve this, many techniques have been studied and developed widely; this is particularly the case for treatment with binders, such as cement, lime, bitumen, and for the inclusion of metallic reinforcing elements put in place during construction as for "reinforced earth". or after construction as for the “nailing-.

In recent years geotextiles which are products of the textile industry, relatively inexpensive, in the form of woven, non-woven, grids or composites between these different products have appeared and have been used in association with all kinds of soils. first, as anti-contamination layers, as filters and as drains.

It has moreover been found that among these geotextiles, many are those which have sufficiently high tensile strengths, so that it is justified to also use them as mechanical reinforcement elements in a mass of soils under construction in the image of what is already achieved with metal strips in the case of the already mentioned reinforced earth technique.

Indeed, if we interpose layers of geotextiles between the different horizontal layers of an embankment under construction, they become tensioned, under the combined effect of the weight of the soil and the coefficient of soil friction. geotextile, as soon as the slope of the slope is greater than the angle of slope of equilibrium, corresponding to the material considered. If the tensile strength of the geotextile, the self-geotextile friction coefficient, and the number of intercalated layers are correctly dimensioned, we can then stiffen the slope of the embankment slope as much as necessary until it reaches the vertical.

This constitutes, briefly described, the general principle of the reinforcement of the solid masses of grounds, using metallic reinforcements or layers of geotextiles.

The interest of the technique of massifs of soils reinforced with geotextile layers is above all economic, but also technical: this is particularly the case for retaining structures called to be deformed because they are based on unstable soils in place . The flexibility of the works produced with this technique makes it possible to adapt to the deformations of the soil in place, while works constructed of concrete for example, therefore much more rigid, would not support it.

Finally, like any new technique, it opens up prospects, both in the design of new types of structures, and in the production of equipment that could not be economically envisaged with conventional techniques. We can for example think of dikes and hydraulic reservoirs, noise barriers, terraces for use in sports and playgrounds, industrial platforms, agriculture, etc.

Many works of this type have been built throughout the world, but they are relatively modest works, often experimental or temporary.

An important gap exists in the solutions brought to the facing of these works for which one notes either a total absence of facing, leaving the reinforcement geotextile at the mercy of the various aggressions which it can undergo, or very luxurious solutions, in the form concrete or masonry walls, which take away from their economic appeal and in many cases their flexibility.

• - protéger le géotextile de renfort vis-à-vis des agressions qu'il pourrait subir au cours de la vie de l'ouvrage : ultra-violets, vandalisme, agressions mécaniques diverses, etc.
• - permettre les déformations de l'ouvrage principal, et s'adapter à celles-ci qui dans certains cas peuvent être relativement importantes,
• - offrir un aspect esthétique engageant et adaptable aux différents sites où ces ouvrages peuvent être construits (rase campagne, montagne, zone urbaine, etc.).

The object of the invention is to propose a facing solution which does not have these drawbacks but which, on the contrary, is able to simultaneously satisfy and at the best cost the following three functions:

• - protect the reinforcement geotextile from attacks it could undergo during the life of the structure: ultra-violet, vandalism, various mechanical attacks, etc.
• - allow the deformations of the main structure, and adapt to these which in some cases can be relatively large,
• - offer an engaging and adaptable aesthetic aspect to the different sites where these works can be built (open country, mountain, urban area, etc.).

The object of the invention is achieved by a facing composed of plates individually attached to the slope, at their upper part, by flexible hooking elements, and in that the plates are arranged in substantially horizontal rows, the plates a row partially overlapping the plates of the immediately lower row.

Thus, the flexible attachment and the relative arrangement of the plates allows them to slide over each other, and to follow the deformations of the structure which could develop in the three directions.

This cladding design adapts to all geometries of structures (vertical or non-vertical slope, straight or stepped, profile in rectilinear or curved plane, etc.) as well as the different requirements (aesthetic in particular) imposed by the environment.

The plates are made of concrete, metal, plastic, wood or any other material.

The flexible hooking elements are flexible elements in at least one direction. They can be made up of cables, metal blades, flexible grid, geotextile sheet, etc.

Advantageously, the plates of a horizontal row are offset laterally with respect to the plates of the immediately lower row, so as to better protect the slope.

Advantageously, the flexible hooking elements comprise neighboring rigid horizontal bars hinged together in pairs, the lower bar being articulated to a rigid plate.

Advantageously, the flexible hooking elements comprise a flexible grid.

Advantageously, for a solid mass composed of layers of earth reinforced by geotextile layers whose end beads form the slope, the plates comprise at their upper part flexible hooking elements of which an extreme part is anchored between two layers of earth .

The plates can be positioned as a ferret as the structure rises, and even partially participate in the production of the formwork.

They can also be installed, once the work is partially or completely finished, insofar as the geotextile sheets have been kept waiting at the interface of the layers, after which it will be possible by all suitable means to hang them , or even by fixing them directly on the visible part of the reinforcement geotextile.

This facing technique applies, in general, to all solid masses of soil, whether reinforced or not, as soon as a difficult problem of slope protection (erosion, surface stability) arises. It is sufficient in this case to provide, during construction, the anchor in the _'slope of engaging elements (especially of grids or geotextiles plies) projecting slightly on the slope and on which it will be possible to come hang the plate panels.

The shape of the plates can be adapted to the appearance you want to give to the facing: from the simple flat rectangular plate to the architectural element for decorative landscaping in urban areas.

The invention relates not only to the facing, but also to each individual plate intended for the implementation of this facing: this plate, rigid or semi-rigid and substantially rectangular, has at its upper part flexible hooking elements comprising a part end in flexible grid and an intermediate part formed by articulated bars.

Advantageously, the flexible grid continues inside the articulated bars and the plate of which it forms the frame.

• - la figure 1 représente en perspective le parement d'un ouvrage complexe, réalisé conformément à l'invention.
• - la figure 2 montre en perspective l'agencement des rangées superposées de plaques conformes à l'invention.
• - la figure 3 montre en coupe schématique transversale.au talus la disposition et la fixation des plaques au massif.

Other characteristics and advantages of the invention will emerge from the following description of a nonlimiting example of embodiment of the invention. Reference will be made to the appended drawings in which:

• - Figure 1 shows in perspective the facing of a complex structure, produced in accordance with the invention.
• - Figure 2 shows in perspective the arrangement of the superimposed rows of plates according to the invention.
• - Figure 3 shows in schematic transverse section on the slope the arrangement and fixing of the plates to the bed.

We see in the figures a massif in steep terrain, intended to support a roadway 1, and the slope is coated with a facing composed of plates 2 arranged in horizontal rows. The plates of a row slightly overlap the plates of the immediately lower row, a bit like a slate or flat tile roof.

The plates 2, of generally planar and rectangular shape extend at their upper part by a flexible element intended for their attachment to the slope.

This flexible element comprises an end part in a flexible grid 3, for example made of plastic, and an intermediate part 4 formed by articulated bars 5.

The manufacture of the assembly 2, 3, 4, 5 includes the preparation of a flexible grid which is used not only to form the end part 3, but also the internal reinforcement of the plates 2 and of the bars 5 which have just been poured. around the grid. In this way the plates 2 and the bars 5 are connected to each other in a flexible manner by the “chain 9” wires of the grid.

The same grid can be used to manufacture several adjacent plates (see fig. 2). The weft threads 8 of the grid connecting the adjacent plates can be broken so as not to hinder the relative movement of the adjacent plates.

The massif can advantageously include layers of soil 6 reinforced with geotextile sheets 7. The slope is formed by overlapping beads of geotextile sheets.

According to the invention, the end portion 3 of the grid of the flexible attachment elements is interposed at the time of construction of the block between two superimposed layers. The friction and the deformation of the geotextile sheets 7 against the grid 3 immobilize the latter and therefore achieve the attachment of the plates 2 which depend on it.

A displacement of the plates 2 due to a deformation of the beads of the slope under the thrust of the land remains possible thanks to the flexible attachment according to the invention. On the other hand, the overlapping of the plates 2 and the presence of the bars 5 reduce the exposure of the beads to external actions (solar radiation, bad weather) to the minimum and ensure the longevity of the slope.

Of course, the upper part of the massif comprises in addition to the floor 1 the usual equipment elements such as a border 12 which can support on the one hand safety rails 10 and on the other hand, special facing plates 11 intended to cover the upper row of plates 2 according to the invention.

Naturally, the invention applies to earth masses or similar materials, such as industrial waste, etc.

Claims (8)

1. Facing for the bank of a mass of earth or like material, characterized in that it is composed of plates (2) individually hooked to the bank by supple hooking elements (3, 5), and in that the plates (2) are disposed in substantially horizontal rows, the plates (2) of one row partially overlapping the plates (2) of the row immediately therebeneath.

2. Facing according to claim 1, characterized in that the plates (2) of one horizontal row are offset laterally with .respect to the plates (2) of the row immediately therebeneath.

3. Facing according to any one of claims 1 or 2, characterized in that the supple hooking elements (3, 5) are elements which are flexible at least in one direction.

4. Facing according to any one of claims 1 to 3, characterized in that the supple hooking elements (3, 5) comprise adjacent rigid horizontal bars (4) articulated on one another in pairs, the lower bar being articulated on a rigid plate (2).

5. Facing according to any one of claims 1 to 4, characterized in that the supple hooking elements (3, 5) comprise a flexible grid (3).

6. Facing according to any one of claims 1 to 5, for a mass of soil composed of strata (6) of earth reinforced by sheets (7) of geotextile of which the end edges form the bank, characterized in that the plates (2) comprise in their upper part flexible hooking elements (3, 5) of which an end part (3) is anchored between two strata of earth (6).

7. Facing plate for use with the facing according to any one of claims 1 to 6, characterized in that it is rigid and substantially rectangular, and comprises in its upper part flexible hooking elements (3, 5) comprising an end part (3) in the form of a flexible grid and an intermediate part (5) formed by articulated bars.

8. Plate according to claim 7, characterized in that the flexible grid (3) continues inside the articulated bars (4) and the plate (2) of which it forms the reinforcement.

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