EP0235101B1

EP0235101B1 - Device for stabilizing bulk material, especially soil masses

Info

Publication number: EP0235101B1
Application number: EP87850010A
Authority: EP
Inventors: Carl Rolf Hallberg
Original assignee: PLATON AS
Current assignee: PLATON AS
Priority date: 1986-02-24
Filing date: 1987-01-16
Publication date: 1990-08-08
Anticipated expiration: 2007-01-16
Also published as: BR8700619A; DE3764115D1; EP0235101A3; DK83887A; DK83887D0; EP0235101A2; JPS62197522A; NZ219238A; ES2017107B3; CN1007365B; GR3000709T3; JPS62273326A; FI870085A0; AU596646B2; YU11687A; CA1265679A; FI870085A; IL81369A0; BG48813A3; AU6920887A

Abstract

The invention relates to a device, esepcially for stabilizing soil material, comprising a substantially elongated web (l) which in mounted position on a support (4) forms a plurality of cells or pockets. For the purpose of providing a device which can be manufactured from inexpensive raw material, which possibly can easily decompose, and which can be manufactured in accordance with a simple and preferably known process, and at the same time render a minimum transport volume, and which in connection with soil stabilizing provides favourable anchoring in the ground which is to be soil stabilized, and which forms pockets or cells having walls extending vertically independent of the slope angle of the ground for stabilizing the soil even during heavy rain, it is according to the invention suggested that the web (l) is constituted by an initially relatively thin, substantially flat web (l), preferably of flexible plastics, which in a first direction is provided with rows of consecutively arranged slits (2,2a, 2b) which are so staggerd relative to each other that the web (l) by the stretching thereof in a second direction forms oppositely undulating strips (3a,3b,3c) which upon mounting of the web on a more or less inclined hill define side by side arranged cells or pockets (8) which can be filled with soil (9) being stabilized by the device. Due to the sharp lower edges (l0) of the undulating strips (3a,3b,3c) the device (l) in stretched condition will easily be pressed down into the ground (4) for the anchoring thereof in the ground (4), and the various degrees of stretching can be harmonized to the various angles of inclination of the ground on which the device is to be carried.

Description

Field of the invention

The present invention relates to a device, generally for stabilizing bulk material and more specificly for stabilizing soil masses, comprising a substantially elongated web which in mounted position defines a plurality of cells or pockets.
The invention also relates to a method for stabilizing bulk material, especially soil masses.
The invention also relates to a special use of such a device.

State of the art

In connection with stabilizing soil masses and especially slopes, it is previously known various products. For example there may be used a net which is made from plastics or steel wire. These types of nets will function satisfactorily provided the slope is not too inclined and provided the soil masses are not influenced by heavy rain before the planting of bushes or similar.
Another type of device for stabilizing soil comprises plastics plates which are streched in both directions after first having been provided with holes. Examples of such plates are known from Norwegian Patent Specifications 134 995, 152 611 and 152612.
It is true that the stretching of the plates or the webs results in a net configuration which has a larger depth or thickness than usual flat wire netting, but they do not provide an earth stabilizing effect in the form of stage-wise arranged pockets.
DE-A 1 915 523 discloses another type of soil stabilizing device and such includes slotted sheet material inteded on stretching to form undulating soil engaging projections. Still another product comprises multi-edged cells which together define an element. These elements can be interconnected to cover a slope, the elements having a certain height, for example 90 mm., a fact which makes it possible for the elements to hold a substantial amount of soil also in slopy terrain. However, the production of such elements involves not only a larger quantity of plastics material but also a more costly production as such. Besides, the elements require a large volume during transport, a fact which involves higher transport expences even if the elements to a certain degree can be stacked on top of each other.
Further, there are known so-called semi-rigid, three-dimensional geotextiles of honeycomb type made from non-woven polyester for stabilizing the top layer of road embankments, river-banks and similar. This type of stabilizing device can be transported in collapsed form and is easy to put into position on the site of use. However, the production of such geotextiles is very sophisticated and costly, the product itself being too soft for rendering a sufficient anchoring effect in the ground onto which it is to be mounted. Besides, the walls of the cell structure of the completely installed geotextile will extend under a right angle from the plane of the ground, also when an inclined slope is the case, a fact which involves that the soil which has been filled into the cells and is to be stabilized, more easily will flow out of the cells or pockets due to heavy rain showers.

General description of the invention

The object of the present invention is first of all to give instructions for a device for stabilizing soil masses, and then a device which does not suffer from the disadvantages inherent in the prior art devices, the favourable caracteristics thereof being preferably retained.
In other words, according to the invention it is aimed for a soil stabilizing device conforming to the following requirements:

I. It is to be manufactured from relatively inexpensive raw material.
2. The speed of disintegration should be varied, from for example easily decomposable in connection with soil areas which are easily overgrown, to a disintegration which takes place over several years.
3. The process of manufacture should be simple and preferably based on prior art.
4. The device should require a small transport volume and the mounting on the site should be simple.
5. The device should have an inherent good faculty of anchoring.
6. The cells or the pockets which are formed during mounting should have walls which possibly can be regulated, and which preferably should extend vertically independent of the inclination of the slope to optimize the stabilizing effect on the occurance of heavy rain showers.

According to the invention the above requirements are met in connection with a device of the type stated in the preamble, which is characterized in that the web is constituted by an initially relatively thin, substantially plane web, preferably made of bendable plastics, which in one direction is provided with rows of subsequently arranged slits which are so staggerd relative to each other that the web when being stretched transversly relative to the slit form oppositely undulated strips which through a suitable mounting define side by side arranged cells or pockets. By spreading the transversely stretched device on a slope, the cells or pockets can be filled with soil which is to be stabilized by the device.
In other words, a flat web is taken as a basis for the present device, said web being provided with the above stated slits, and allowing for production in larger or lesser rolls for storage and transport. Thus, the web can be transported to the place of use in rolls rendering a minimum transport volume. Only at the site, i.e. after the web has been spread out on the ground and has been stretched in the direction transversely to the slits, there will be formed upwardly extending backs or walls, which in turn form pockets which stabilize the soil which after the stretching is filled into the pockets of the device. The web can then in advance have been cut in apropriate lengths depending on the landscape or the ground which is to be prepared for soil stabilizing.
During the mounting of the device, this is not subjected to any permanent deformation, since the soil masses which are filled into the pockets will keep the web in position in "stretched" condition.
Another special feature of the present device is related to the small thickness of the web, the stretching thereof implying that sharp lower edges appear along the undulating strips, and said sharp edges can easily be pressed into the ground when mounting the web on the site, a fact which entails a secure anchoring of the device even in steep slopes.
A further feature of the present device is to the fact that by various degrees of stretching there can be achieved various mutual angles between the wall portions of the undulated strips, and that various degrees of stretching can be used for various slope angles of the ground which is to carry the device. Various degrees of stretching will also give different sizes of the cells or pockets, giving larger possibility of selecting a device structure depending on the shape of the terrain.
Alternatively, the device may be placed on a support and serve as a guard for sand, snow or similar.
In the area of each slit there may be provided an edge area taking the form of bulging or embossment, which in connection with the stretching will ensure that the undulation of the corresponding strip portions takes place in the right direction relativ to other strip portions.
To achieve a correct direction of the undulation of the strips during mounting of the device according to the invention, the plastics web may during the production thereof while still being soft and hot, be subjected to an initial stretching transversly to the slits. This initial stretching may be effected so far that the individual strip portions have embedded thereinto a "thermal memory", or a permanent initial plastic deformation which is to point out the direction in which the strip portions are to undulate during the final and complete stretching of the web on site.
For example, the "thermal memory" or the initial stretching may be effected in the area of the slits, for example by means of combined slitting and pressing rollers.
This small pre-stretching will give some bulging of the said strip portions, especially in the area of the slits, but the flexible web will still be substantially flat and can thus be tightly rolled up in rolls for storage and transport.
Possibly, the slits may at each end be provided with curved portions for resisting breakage when the web is stretched.
Further, the web may be laminated with a suitable woven or knitted cloth, especially for reinforcing the end portions of the slits.
Preferably the web is manufactured from plastics, for exam ple polyethylen. Suitable additives to the plastics may vary the resistance agianst decomposition.

Brief description of the drawings

The invention will in the following be further disclosed with reference to the attached Figures illustrating embodiments and fields of application for the present stabilizing device.

Fig. I is a schematic plan view of a web forming the basis of an embodiment of the present device.
Fig. la is a section of a web according to the invention, whereas
Fig. Ib is an enlarged section of an area of the device according to Fig. la.
Fig. 2a is a perspective view illustrating the various phaces of the stabilizing process in which the device according to the invention is to be used, the upper part of the Figure illustrating the device in mounted position, the center portion of the Figure illustrating the device covered with soil material, and the lower portion of the Figure illustrating the stabilized area after a growing season.
Fig. 2b is an enlarged fraction of the area indicated in Fig. 2a.
Fig. 3 illustrates on a larger scale a fraction of a section through the device according to Fig. 2a as seen in the direction III-III in Fig. 2a.

Description of preferred embodiments

In Fig. I which illustrates schematicly a top view of a web which forms the basis of an embodiment of a device according to the invention used as a soil stabilizing device, the web itself is designated by reference numeral I, the web appropriately being manufactured through an extrusion or calender process of a plastics material to a web having a thickness from for example 0.1 to 6 mm. The thin substantially plane web I of preferably flexible plastics material is during the manufacturing provided with rows of consequtively arranged slits, for example by punching or slitting, the slits 2 in the first row being arranged substantially with even spacing, whereas the slits 2a of the adjacent row is arranged with the same spacing but staggert relative to the slits 2 of the first row. The next row of slits 2b are provided parallel to the slits 2 of the first row, and there is in this way provided a slit pattern which by an appropriate stretching of the web I creates op- positily undulating strips 3a,3b,3c etc., as this is specially appearent from Fig. 2a.
The plastics web which in Fig. I is designated by I, is during the manufacturing thereof slitted or punched, so as to comprise a plurality of rows of slits 2,2a,2b etc., the number of rows being chosen according to the field of application of the finished manufactured web. Thus, the web can be manufactured in desired width and can be delivered as rolls or as individual web-shaped plates. In Fig. la there is shown a section of a web I which has been rolled or spread out on a support onto which the soil masses are to be stabilized. If the slits are made transversely to the production line direction of the web and the web is rolled up in this direction, a web which is rolled out on site will there be stretched in the longitudinal direction, i.e. in the same direction as the rolling out.
When the plastics foil or plastics web I has been rolled out or spread out on a support, for example a sloping ground 4, as this appears from Fig. 2a, there will by appropriate stretching of the web I as symbolized by the arrow P in Fig. la, be provided oppositely undulating strips 3a,3b,3c. These strips will have alternating concave and convex portions 5 and 6, respectively, as a result of the slits 2,2a,2b, whereas at the interconnected web zones retained between the slits, here the zones 7, here will have a relatively straight form. In other words, there are provided side by side arranged or stage-shaped cells or pockets 8 which can be filled with soil which is stabilized by the device I.
At the top of Fig. 2a there is shown a fraction of a web I which has been stretched transversly to the slits, and which has been placed on a sloping ground 4, for example of soil or gravel, whereas in the middle of Fig. 2a it is shown how the cells or the pockets 8 have been filled with soil 9 which is stabilized by the device I. The stretching gives the web I a substantially non-permanent deformation which however will be retained by the filling of soil mass 9. The upwardly extending backs or walls of the undulations 3a,3b, 3c do not only form pockets 8 but also render a favourable anchoring due to the sharp lower edges 10 which bury themselves fairly well into the ground, as this is especially illustrated in Fig. 2b.
Because the web I in its stretched condition can be pressed deeply into the ground, it will not slide even in steep slopes. This condition is eve better illustrated in Fig. 3, in which the device I is pressed down into an especially steep hill 4a, and in which the walls of the undulations 3a,3b,3c will still extend vertically from the ground for the forming of cells or pockets 8 having vertical backs or walls. This vertical arrangement of the backs or the walls will aside from rendering a favourable anchoring also give an especially good stabilization of the soil 9 and the pockets during heavy rain.
As appearing from fig. Ib there may in the area of each slit 2,2a,2b etc. be arranged bulge or embossing II, which during the stretching of the web I will aid in that the corresponding stip portion will undulate in the correct direction relative to other strip portions.
An alternative way to have the individual strip portion undulate in the correct direction during the stretching of the web on site, is to the fact that the plastics web when this is still soft and hot during the production thereof, is subjected to an introductory stretching in the area of the slits, as this is further disclosed in the preamble of the specification.
In Fig. la there is also illustrated a fixing peg 12 which during the speading of the web I on a sloping ground 4, is inserted through a slit 2 below the upper strip 3a, the peg 12 at its lower end being provided with barbs 12a serving for the attachement to the ground, and which at its upper portion is provided with arms 12b for supporting the upper strip 2 when the web I is stretched out as illustrated in Fig. 2a.
At the bottom of fig. 2a it is shown how the landscape, in which is utilized the soil stabilizing device according to the invention, can appear after a growth season, the top of the soil 9 now being overgrown by a lawn 13 having its roots extending down into the soil 9.
It is to be understood that in the openings or the pockets 8 in the web I there can also be planted bushes or similar, all in dependence of the landscape which is to be shaped by means of the soil stabilizing device.
The material from which the web I is to be manufactured, can for example be a plastics material filled with carbon black, a fact which renders the plastics very resistant to decomposition. Possibly, the plastics may be manufactured without any fillers or be mixed with pigments making the web chemically instable, a fact which involves that the plastics will disappear after some years out in nature.
If there is used a thicker plastics web as a soil stabilizing device it may be necessary to use mach- anical power for the stretching thereof. This may in some cases be necessary, but the web is preferably manufactured as a flexible plastics web which can be stretched on site by means of manual force.
Possibly it may in connection with thicker plastics webs be used heat treatment, such that the plastics in its stretched condition will retain its stretched configuration, and the web could then be used for heavier stabilizing objectives, for example stabilizing temporary roads or areas, military airports or similar.
Alternatively, the present device can be mounted on a support to serve as a guard for sand, snow or similar.
In this connection it may be appropriate to use a somewhat thicker web which is stretched on a rack or rail or between poles which are located along a railway or a road being especially exposed for the accumulation of whirling snow or sand. By means of the present device the snow or sand particles could be guided so as to be collected in snowdrifts or sandheaps where they are apt to make the least damage, respectively are to least inconvenience.
It is to be understood that the device according to the invention also can be used as awning, for example for protection against sunshine, light, radiation etc.
Of course it can in this connection be used materials of various quality, colour, translucence etc. The device can then be pre-mounted on a frame which can be mounted in position on the site where it is to be used.

Claims

1. Device, especially for stabilizing bulk material, comprising initially relatively thin, substantially flat web (1), preferably of flexible material, which in a first direction is provided with rows of consecutively arranged slits, (2, 2a, 2b etc.) which are staggered relative to each other, characterized in that in the area of one or more slits (2, 2a, 2b) there is provided a bulge or embossing (11) which during the stretching of the web serve for the undulating of the corresponding strip portion in its right direction relative to the other Strip portions, so that the web (1) after the stretching thereof forms oppositely undulating strips (3a, 3b, 3c) defining side by side arranged cells or pockets (8) which can be filled with soil which is stabilized by the device (1).

2. Device as claimed in claim 1, characterized in that the web (1) comprises a "thermal memory" or an introductory transverse stretching which is effected during the production of a plastics web, and which will initiate the direction in which the strips are to undulate during the final stretching on site.

3. Device as claimed in claim 1 or 2, characterized in that the "thermal memory" or the initial stretching may be effected in the area of the slits, for example by means of combined slitting and pressing rollers.

4. Device as claimed in any of the claims 1-3, characterized in that the oppositely undulating strips (3a, 3b, 3c) which are formed by the stretching of the web (1) comprise undulating edge portions (1) which can easily be pressed down into the ground (4) and thereby ensure anchoring of the device (1) on site.

5. Device as claimed in any of the claims 1-4, characterized in that various degrees of stretching of the web (1) renders various mutual angles between the wall portions of the oppositely undulating strips (3a, 3b, 3c), so that various degrees of stretching can be used in dependence of the sloping angle of the ground (4) which is to carry the device (1 ).

6. Device as claimed in any of the preceding claims, characterized in that at the ends of the slits (2) of the web (1) there are provided curved portions to resist breakage when the web (1) is stretched transversely relative to the slits.

7. Device as claimed in any of the preceding claims, characterized in that the web is laminated with a suitable woven or knitted cloth for further reinforcement of the end portions of the slits (2).

8. Device as claimed in any of the preceding claims, characterized in that the web (1) is manufactured from plastics, for example polyethylene.

9. Method for stabilizing bulk material, especially soil masses, including the use of a relatively thin, substantially flat web (1) preferably of flexible material, which in a first direction is provided with rows of consecutively arranged slits (2, 2a, 2b), the web in suitable ringlets being spread out on a flat or sloping ground (4) which is to be soil stabilized, characterized in that there is used a web (1) during its manufacture provided with bulges or like means (11) which ensure a predetermined undulation of strips (3a, 3b, 3c) when said web (1) is stretched in a second direction (3a, 3b, 3c), that the web after being spread out on the ground (4) at its one longitudinally extending edge being attached to the ground (4) by means of appropriate fixing means (12), and that the web (1) thereafter is stretched in the second direction of the forming of oppositely undulating strips (3a, 3b, 3c) which in turn define side by side arranged cells or pockets (8) which can be filled with soil which is stabilized by the device (1).

10. Method as claimed in claim 9, characterized in that the web (1) after the stretching will have its lower edge portions (1) of the individual undulated strips, (3a, 3b, 3c) pressed into the ground (4) for anchoring of the device (1) in the ground (4).

11. Method as claimed in claim 9 or 10, characterized in that the web (1) on the site of use is stretched in the second direction for through non-permanent deformation to define said cells or pockets (8), the deformation being retained by the filling of soil (9) in said cells or pockets (8).

12. Method as claimed in claims 9 to 11, characterized in that the web (1) in a suitable length is attached to a rack along one of its end edges, and that the web (1) is thereafter stretched in a direction for the forming of oppositely undulating strips (3a, 3b, 3c) which in turn define side by side arranged cells or pockets (8) serving to guard against whirling sand, snow or similar.

13. The use of a device as claimed in one of the claims 1-8 as an awning, for example for protection against sunshine, light, radiation etc.