FR2615542A1 - DEVICE FOR STABILIZING SLOPES AND SLOPES AGAINST INSTABILITIES OF SURFACE LAYERS AND CLOSE TO SURFACE - Google Patents

Abstract

THIS DEVICE INCLUDES A FLEXIBLE NET 1 CONSISTS OF SEVERAL PARTIAL NETS 20 JOINED TO ONE ANOTHER BY A STEEL CABLE 4. TO PROTECT A SLIP OR A SLOPE FROM SLIDES OF LAYERS CLOSE TO THE SURFACE AS WELL AS SURFICIAL SLIDES. THREAD 1 ON THE SURFACE OF THE SLOPE OR SLOPE BY MEANS OF SHORT ANCHOR BOLTS 2 CONCRETE, THESE BOLTS 2 AND THE NET 1 THEN FORMING A COHERENT ASSEMBLY. IN THE CASE OF A SURFACE NOT COVERED WITH VEGETATION, IT IS PROVIDED TO PLACE UNDER NET 1 A GEOTEXTILE 5 WHICH LET THROUGH THE GROWTH OF VEGETATION.

Description

The invention relates to a device for

  stabilize the slopes and slopes against instants

  bilities of the surface layers or close to the surface

  face, in particular, to protect them from attacks by erosion and landslides comprising a flexible thread which is extended over the area to be protected and a large number of anchor bolts which are anchored in the ground, at a certain mutual spacing and which one fixes with the net.

  It is often necessary to protect

  manage steep slopes and slopes, particularly in mountainous regions, erosion attacks and landslides. In many cases, stabilization

  embankments by planting vegetation is sufficient

  you. However, it is common that nature does not

  not to establish or maintain uninterrupted vegetation cover. This is particularly true for the upper layers of embankments and trenches. It is known to protect such slopes and slopes by walls of

  support, anchor bolts and anchors

  thrown. However, these means are expensive and they are not always satisfactory, either from the point of view

  aesthetic or that of environmental protection-

is lying.

  According to patents JP-A-5,536,576 and JP-A-

  6 128 620, anchor threads and bolts are used

  to protect the cultivated land from landslides

  laid on a rocky subsoil. Slopes with loose basements cannot be stabilized against erosion and slippage using the devices

  described in these documents. It is known, by the US-A-

  1,597,114, to use a doormat or a covering with which it is intended to avoid erosion due to currents in hydraulic structures. This device is not intended to protect the slopes and slopes and it would even be ineffective in these cases. As a result of FR-A-2 182 251, a textile covering for slopes and slopes is known, but this covering has no static function and is incapable of preventing erosion and

landslides.

  It is also known that the basement of slopes

  can be fixed with anchor bolts, nozzles or che-

  cities. Furthermore, it is known that rocky slopes

  can be protected by nets that prevent falling

your stones.

  In a slope, we must distinguish, from the point of view of soil mechanics, the following three stability mechanisms: - deep slides slides of the layers close to the surface

- superficial sliding.

  Deep slips occur when

  the shear strength of the basement is exceeded.

  These slippages are avoided by known methods, at

  using anchor bolts or stilts, sub walls

tenement or equivalent. -

  Slips or solifluxion movements

  layers close to the surface, up to a few meters

  very deep, occur under the effect of an am-

  ground furnishings due to the circulation of pre-

  cipitation and runoff, by internal erosion, frost, as well as due to too low pressure of the

  overlapping layers. So far, we have not granted

  there is a lot of interest in these stability issues. All-

  However, this has been remedied by drainage, for example by means of Y-shaped ditches. Superficial landslides are triggered by precipitation water, frost, snow pressure, falling rocks and the like. As

  countermeasures, mainly planting is planned

  requested, at most temporarily protected by other

very measures.

  While deep landslides are the subject of in-depth studies in soil mechanics, the two surface displacement mechanisms have hardly

  aroused interest. Damages are generally attributed to

  to steep slopes or an error in the

  choice of vegetation.

  The object of the invention is to create an arrangement

  sitive of the kind cited at the beginning by means of which the two aforementioned kinds of surface sliding can be

  effectively avoided both in the short term and in the long term

  me. The device must be of a simple construction, be able to be mounted in a simple way and allow the

  growth of natural vegetation. In addition, the dis-

  positive should work well, even on uneven ground. This problem is solved by the invention which is characterized in that the net is composed of a plurality of partial nets which are tensioned by means of tensioning means interposed between them, in that the

  anchor bolts are arranged between the threads

  and in that, on the anchor bolts, are arranged

  - these means which connect the anchor bolts to the

partial lets.

  With the device according to the invention, it is possible

  protect slopes and slopes from erosion and slippage

  superficial cements-up to a few meters deep-

  deur without having to use large terrace machines-

  is lying. Even in difficult conditions and hard-to-reach terrain, it is possible to

  achieve total plant cover.

  An essential principle of the invention is that each anchor bolt is securely connected to the other anchor bolts by means of the tensioned net, so that a force which acts on an anchor bolt in a transverse direction to the longitudinal direction of this anchor bolt is immediately transmitted to the others

  anchor bolts. The force that attacks a bolt of an-

  is thus distributed over several anchor bolts

  and in this way we avoid the deformation of the bolt of an-

  crage that was attacked in the first place. The net thus forms with the anchor bolts an assembly which resists the solifluxion pressure of the slope or slope. The net is composed of a plurality of partial nets which are joined to each other and stretched with respect to each other. Partial nets are flexible and can be rolled up and therefore transported in a simple way. The net or partial nets are preferably made of steel cables, so that they are flexible and at the same time they

  are able to withstand great trac-

tion.

  Partial fillets can simply be

  pretended and stretched with steel cables in no

  which arrangement is worn, so that large areas of slope can also be stabilized. By squeezing the

  anchor plates, the nets are stretched even more.

  Establishment of plant cover and,

  therefore, rooting of the soil occurs

  quick and safe lesson, even in unfavorable conditions

  bles, when a geotextile has been placed under the net through which vegetation can grow and which serves as a support layer for seeds, or when spreading

  the geotextile on the net and that it is fixed to this

  deny. If, on the other hand, the net has a mesh width of 5 to about 30 cm, it is possible to grow not only low plants and grasses, but also

  bushy plants and trees.

  Other features and advantages of the

  vention will be better understood on reading the description

  tion which will follow several exemplary embodiments and with reference to the accompanying drawings, in which,

  Figure 1 is a partial perspective view

  ve of a device according to the invention;

  Figure 2 is a perspective view of a dis-

  positive according to the invention; Figure 3 is a partial section of an embankment equipped with the device; Figures 4a and 4b show an equal slope

  pe of the device according to the invention before and after the formation

plant cover;

  FIG. 5 represents a device implemented

lives on uneven ground;

  Figure 6 is a partial section of the embankment

  dressed in a device according to the invention.

  As shown in Figures 1 and 2, the provision

  sitive according to the invention comprises a net 1 which is com-

  laid with a plurality of partial nets 20. These nets are joined together and stretched relative to each other by metal cables. 4 and they present

  each a border 6 formed of a metal cable in an-

  neau closed. The connecting cable 4 surrounds the border cables 6 and is fixed by collars 22. The mesh width of the nets 1 is preferably about 5 to 30 cm and the lengths of the sides of the partial nets 20 are about 3 m. The metal cables 7 are fixed by knotted collars 8 and normal collars 8. The partial threads 20 are preferably rectangular but they can also have another suitable shape.

  The device according to the invention comprises in or

  be short spikes or anchor bolts 2 which are re-

  shown in Figure 3, and which are set up in

  holes drilled or even driven by threshing and concrete-

  born in the ground by means of a mortar 10, so

  that they can resist a tearing force of more

  tons. The length of the short anchor bolts 2 is calculated so that their lower end is embedded in a relatively compact layer of ground 11 located below a sliding interface 21. Usually, this length is between 2

  and 3 m but, naturally, in certain circumstances

  stances, this length can be changed.

  Each short anchor bolt or each spike is threaded through an anchor plate presenting on

  its underside of hooks 13 which project per-

  pendulum and by means of which the bolts of an-

  short crage 2 are rigidly connected to the net 1. The anchor plates 3 are made of a suitable metal and

  they can be square, as shown in the figure

  re 1, or triangular, as shown in Figure 2, but it is also possible to imagine other shapes. The net 1 can be placed directly on the ground. However, in the case of a surface which is not yet covered with vegetation, it is preferably spread under the net 1 a geotextile 5 which can be traversed by the growth of the vegetation, as indicated in the figure 3. Geotextile 5 serves as a support layer for seeds and it also serves as protection against erosion between the cracks until the

  vegetation is sufficiently rooted.

  FIG. 5 clearly shows that, even in the case of uneven ground, the net 1 can be laid

  optimally thanks to an appropriate choice of

  partial lets 20 and their mutual orientations.

  As shown in FIG. 4a, the net 1 is placed on the embankment already coated with a geotextile 5 and, thereafter, vegetation is grown there. The mesh width of

  nets are used to plant trees or shrubs.

  To put the device in place on the ground

  rain to be protected, the desired number of partial nets 20 are laid on the ground, at the appropriate spacing and orientation, possibly after the prior installation of a geotextile 5 or doormats, and then the nets are assembled using steel cable 4. Next, we tighten the net 1 and anchor the short anchor bolts 2

  in the ground. If it is necessary to carry out a pro-

  tection at great depth against sliding,

  can also add additional protective means

  tion known as, for example, anchor bolts

  clinging in the ground or in the rock, a long

  appropriately, build retaining walls or stilts and, here too, the device according to the invention essentially guarantees the stability of the soil in the

  layers close to the surface. It is visible that the po-

  se of the device according to the invention does not require a

  large amount of manual labor and that it can be done

  kill even in hard-to-reach terrain.

  The soil stabilization effect of the device according to the invention will now be described with reference to the

  figure 6. The upper layer 23 of the terrain, relative-

  loose, threatened by erosion tends to creep parallel

  Lely on the slope, in the direction of the arrows A, or push the slope, and it tends to deform the short anchor bolts 2, giving them approximately the position shown in broken lines. The coating

  mortar of the short anchor bolt 2, which serves as a

  smoothing, prevents this deformation by behaving like a peg, according to the forces which act in the direction of the arrows C. The thread 1 prevents at the same time

  the ground surface to lift up and it distributes the for-

  these acting on the short anchor bolts 2 in the direction of arrow C on the other short anchor bolts. It appears from the indications given above

  that we obtain a device that can be manufactured

  economic lesson and which can be laid in a simple way, even in difficult terrain and by means of which, without

  significantly alter the appearance of the landscape, it is possible

  ble To protect embankment surfaces, even if they are large and irregular, against erosion and sliding of the layers close to the

  surface, both short term and long term.

  Of course, various modifications may be made by those skilled in the art to the devices which have just been described, only by way of examples.

  non-limiting, without departing from the scope of the invention.

26 1 5542

Claims (6)

  1 - Device to stabilize the slopes and worms   against the instabilities of the surface layers   skies and close to the surface, especially for   protect them from attack by erosion and sliding   ground elements, this device comprising a flexible net (1), which extends over the area to be protected and a plurality of anchor bolts (2) which are anchored in the ground-at a certain mutual spacing and which 'we fix at   net (1), characterized in that the net (1) is composed   an olurality of partial fillets (20) which are tight   due to the aid of tension means (4) interposed between them, in that the anchor bolts (2) are arranged   between the partial threads (20) and in that, on the bou-   anchor bolts (2) are mounted means (3) which   connect the anchor bolts (2) to the partial threads (20).   2 - Device according to claim 1, charac-   terized in that the partial threads (20) and the means   (4) are made of metal cables.   3 - Device according to one of claims 1   and 2, characterized in that the anchor bolts (2) are piles or short anchor bolts (2) and are   intended to be concreted in the ground.   4 - Device according to one of claims 1 to   3, characterized in that the means (3) mounted on the anchor bolts (2) are anchor plates which can be tightened to further tighten the net (1). - Device according to claim 4, characterized in that the anchoring plates (2) have hooks (13) to which the partial threads (20) are fixed.   6 - Device according to one of claims 1 to   , characterized in that a geotextile (5) is placed under the net (1) which can be traversed by the vegetation, or that the geotextile is placed on the net (1) and that fixes it to the latter.   7 - Device according to one of claims 1 to   6, characterized in that the net (1) has a width mesh size from 5 to 30 cm.