US20070131917A1

US20070131917A1 - Protective mesh, especially for rockfall protection or to stabilise a layer of soil

Info

Publication number: US20070131917A1
Application number: US11/636,089
Authority: US
Inventors: Stephan Wartmann
Original assignee: Fatzer AG
Current assignee: Fatzer AG
Priority date: 2005-12-09
Filing date: 2006-12-07
Publication date: 2007-06-14
Also published as: CH698850B1; EP1795279B1; CN1978790A; DE502006003595D1; ATE429988T1; JP2007162456A; CN1978790B; EP1795279A1

Abstract

A protective mesh, especially for rockfall protection or to stabilise a layer of soil, is braided out of helically curved wires (11, 12, 13, 14, 15, 16). Rhomboidal meshes (17) are formed and in each case two adjacent helical wires (11, 12, 13, 14, 15, 16) are flexibly held together. The protective mesh (10) has a thickness which amounts to a multiple of the thickness of the wire. In at least some of the braided pairs of wires (11, 12, 13, 14, 15, 16), an essentially straight longitudinal reinforcement element (31, 32, 33, 34, 35) is guided through the coupling area (A) of the two helical wires, causing the rhomboidal meshes (17) to be divided into triangular meshes (17 a, 17 b). In these crucial areas of force transmission of the protective mesh, there are now three instead of two wires meeting, as the result of which the force absorption capacity of the protective mesh is substantially increased.

Description

The invention relates to a protective mesh, especially for rockfall protection or to stabilise a layer of soil, in accordance with the preamble of claim 1.
A protective mesh of this type, which is either laid out on the soil surface or can be fixed in an approximately vertical position on a slope, is disclosed in EP-B-0 979 329. The protective mesh is braided out of helically curved wires in such a way that rhomboidal meshes are formed and in each case two adjacent helical wires are flexibly held together, so that the protective mesh can be folded or rolled up and takes up less room for storage and transport than ordinary wire netting. The protective mesh is three-dimensional and has a thickness which amounts to a multiple of the thickness of the wire, due to the high tensile strength of the wires, even in stretched condition, which means that when used as a slope stabiliser, better conditions are produced for the fixation of layers of vegetation or to hold humus or sprayed layers on the covered ground.
In place of individual helically curved wires, it is also possible to braid helically curved wire strands, wire cables or wire bundles into a protective mesh, such as that disclosed by EP-B-0 979 329 (cf. EP patent application no. 05 740 963.3), as the result of which a protective mesh with an especially high strength is created.
The present invention is based on the problem of yet further improving a protective mesh of the aforementioned type and further increasing its force absorption capacity.
This problem is solved according to the invention by a protective mesh with the features of claim 1.
Further preferred embodiments of the inventive protective mesh form the subject matter of the dependent claims.
According to the invention, in at least some of the pairs of wires or wire elements an essentially straight longitudinal reinforcement element is guided through the coupling area of the two helical wires or wire elements, i.e. through the intersecting curves thereof, causing the rhomboidal meshes to be divided into triangular meshes and with which the two wires or wire elements are in flexible connection. The reinforcement elements greatly reduce deformations and distortions in the coupling areas A of the adjacent wires or wire elements (by up to 60% in comparison with the protective meshes of prior art from EP-B-0 979 329) and ensure that the radius of curvature of the helical wires or wire elements is retained to a very large extent in the contact area. In these crucial areas of force transmission of the protective mesh, there are now three instead of two wires or wire elements meeting, as the result of which the force absorption capacity of the protective mesh is substantially increased. Tests have shown that the breaking load in the main direction (axis of longitudinal extension) can be increased by up to 30% which of course also means the breaking force in the transverse direction can also be substantially increased.
The inventive protective mesh also has increased lateral rigidity, which can be influenced by the choice of reinforcement elements.
The rhomboidal meshes can also be enlarged by comparison with the mesh according to EP-B-0 979 329, since the reinforcement elements ensure that the mesh size does not become over-large. This enables the manufacturing expense to be considerably reduced (by about 50%).
According to the invention, not only can new, improved protective meshes be produced at less expense, but also existing mesh constructions can be retrofitted with the reinforcement elements. This retrofitting can fulfil three aims: reducing deformations, increasing breaking load and/or reducing mesh size.
The invention will next be explained in more detail with the aid of the drawings, which show:
FIG. 1 an embodiment of an inventive wire mesh in top view;
FIG. 2 an inventive wire mesh in diagrammatic perspectival view, as slope stabiliser on a slope; and
FIG. 3 a cross-section through a part of the wire mesh according to FIG. 1.
FIG. 1 shows a protective mesh 10 (or a part of such a protective mesh), in particular for rockfall protection structures or to stabilise a layer of earth, which is braided out of helically curved wires 11, 12, 13, 14, 15, 16. The helically curved wires have an angle of twist α (preferably 25° to 35°) and a length L between two curves. Two respectively adjacent wires 11, 12; 12, 13; 13, 14 etc. are flexibly connected together in the area of their curves. The connection area, i.e. the area where the curves of two adjacent wires 11, 12, 13, 14, etc. intersect is designated in FIG. 1 by A. A diagonal mesh with rhomboidal meshes 17 is formed by the wires 11 to 16.
The wires 11 to 16 are curved over or fitted with loops 11 a, 12 a, 13 a, 14 a, 15 a, 16 a at their ends, and connected flexibly to each other by these in pairs. There may also be knots, i.e. still further windings may be wound around the loops.
The protective mesh 10 is pre-tensioned by cables 21 in its longitudinal extension and by soil and rock nails inserted at regular intervals with pre-tensioned fixing elements 20 placed on top, as also shown in FIG. 2. For preference, a wire or a cable 21 is looped into the helically curved selvedge wire 11 (FIG. 1) located on the top and bottom end of the mesh 10, said wire or cable being in turn stretched by the fixing elements 20 over the ground or similar. In principle, the fixing elements 20 could, however, also hold the selvedge loops 11′ directly. Soil or rock nails of prior art are used as fixing elements 20, preferably distributed at regular intervals. The protective mesh 10 is pre-tensioned by the cables 21 in its longitudinal extension.
According to the invention, in at least some of the pairs of wires or wire elements 11, 12; 12, 13; 13, 14 etc., an essentially straight longitudinal reinforcement element 31, 32, 33, 34, 35 is guided through the coupling area A of the two helical wires or wire elements, i.e. through the intersecting curves thereof, causing the rhomboidal meshes 17 to be divided into triangular meshes 17 a, 17 b and with which the two wires or wire elements are in flexible connection (the mesh form can take the form of e.g. isosceles or equilateral triangles). In the embodiment shown, all wire pairs are provided with reinforcement elements 31 to 35, which are spaced at regular intervals from each other. It would, however, also be possible to assign reinforcement elements only to every second or third (etc.) wire pair and for them to be spaced irregularly from each other. This has the advantage that the breaking load and especially the deformation capacity could be controlled as required. Equally, it is also possible to obtain different mesh thicknesses under strain, which could achieve a certain optical appearance, for example for architectural purposes.
The reinforcement elements 31 to 35, which are formed by a wire in the embodiment shown, run transversely to the axis of longitudinal extension, and are curved over or fitted with a loop 31 a, 32 a, 33 a, 34 a, 35 a or a knot, at least at one end, while these lateral end elements are either flexibly connected with the corresponding end elements 11 a, 12 a; 13 a, 14 a; 15 a, 16 a of the wire pairs or with corresponding selvedge loops. The end connection on both sides, however, prevents the protective mesh being pushed together.
As can be seen from FIG. 3, the protective mesh 10 has a thickness 10′ which is a multiple, preferably between 3 and 10 times the wire thickness. Even under tensile load, due to this design, the thickness and therefore this mattress-like structure of the protective mesh, is almost completely maintained, which makes a huge difference from other meshes, which mainly lose their original thickness under tensile stress. This, however, also enables the reinforcement elements 31 to 35 to be simply pushed into these curves, each formed from two wires.
Due to the jointed connection of the adjacent wire pairs with each other and with the respective reinforcement element, both in the connection areas A and in the end areas, the inventive protective mesh 10 can again easily be folded or rolled up for storage and transport, in which case, due to suitable formation of loops or knots at the wire ends, any snagging during rolling is largely prevented.
The inventive protective mesh 10 could, instead of individual helically curved wire, also be braided out of wire elements consisting of several wires, such as wire strands, wire cables or wire bundles or similar. The reinforcement elements 31 to 35 could also consist of several wires and be designed as wire strands, wire cables or wire bundles or similar. Equally possible are rod-shaped reinforcement elements, preferably having a round cross-section, or tubular (or tube-like, closed and/or partly closed) reinforcement elements, which enable cables or other elements to be passed through. Rod-shaped reinforcement elements with a semi-circular, triangular or similar cross-section, with a recess for the cables, could also be considered.
In the inventive mesh, the reinforcement elements greatly reduce deformations and distortions in the coupling areas A of the adjacent wires or wire elements (by up to 60% in comparison with the protective meshes of prior art from EP-B-0 979 329) and ensure that the radius of curvature of the helical wires or wire elements is retained in the contact area. In these crucial areas of force transmission of the protective mesh, there are now three instead of two wires or wire elements meeting, as the result of which the force absorption capacity of the protective mesh is substantially increased. Tests have shown that the breaking load in the main direction (axis of longitudinal extension) can be increased by up to 30%.
The inventive protective mesh also has increased lateral (acting in the transverse direction) rigidity, which can be influenced by the choice of reinforcement elements
The rhomboidal meshes can also be enlarged by comparison with the mesh according to EP-B-0 979 329, since the reinforcement elements ensure that the mesh size does not become over-large. This enables the manufacturing expense to be considerably reduced (by about 50%).
Both the helically curved wires or wire elements forming the protective mesh and the straight reinforcement elements are made of steel and are usually corrosion-protected in various ways (Zn, Zn—Al coated, stainless steel, plastified, etc.) For preference the helically curved wires or wire elements (wire strands, wire cables or wire bundles) and/or the straight reinforcement elements are made at least partly from high-tensile steel with a nominal tensile strength of between 1,000 and 3,000 N/mm²(DIN norm 2078), in which case these may also be spring steel wires according to DIN norm 17223.
Due to the substantially increased force absorption capacity, however, the protective mesh may also consist at least in part of a steel with lesser strength. It is especially advantageous to combine helically curved wires or wire elements made from a high tensile strength steel with reinforcement elements made from a steel with a lesser strength, in which case, when the latter is being installed, due to its permanent deformation, a terrain adaptation or “conformity” to the surface of the terrain and thus to unevenness in the terrain can be undertaken. It is equally possible to enhance the deformation reduction still further by selective local pre-deformation of these wire elements.
According to the invention, not only can new, improved protective meshes be produced at less expense, but existing mesh constructions can also be retrofitted with the reinforcement elements. This retrofitting can fulfil three aims: reducing deformations, increasing breaking load and/or reducing mesh size.

Claims

1. Protective mesh, in particular for rockfall protection structures or to stabilise a layer of earth, which is braided out of helically curved wires (11, 12, 13, 14, 15, 16) or helically-curved wire elements (wire strands, wire cables or wire bundles) consisting of several wires, such that rhomboidal meshes (17) are formed and in each case two adjacent helical wires (11, 12, 13, 14, 15, 16) or wire elements are flexibly held together, and the protective mesh has a thickness which amounts to a multiple of the thickness of the wire or wire element, characterised in that in at least some of the pairs of wires or wire elements (11, 12, 13, 14, 15, 16) an essentially straight longitudinal reinforcement element (31, 32, 33, 34, 35) is guided through the coupling area (A) of the two helical wires or wire elements, i.e. through the intersecting curves thereof, causing the rhomboidal meshes (17) to be divided into triangular meshes (17 a, 17 b) and with which the two wires or wire elements are in flexible connection.

2. Protective mesh according to claim 1, characterised in that the reinforcement element (31, 32, 33, 34, 35) is designed as a single wire, as two or more wires, a wire strand, a wire cable or a wire bundle.

3. Protective mesh according to claim 1, characterised in that the reinforcement element (31, 32, 33, 34, 35) is designed as a rod or a tube with a round cross-section.

4. Protective mesh according to claim 1, characterised in that the reinforcement element (31, 32, 33, 34, 35) is designed as a rod with a semi-circular cross-section and with a recess to hold cables or other elements.

5. Protective mesh according to claim 1, characterised in that both the wires (11, 12, 13, 14, 15, 16) or wire elements and/or the reinforcement elements (31, 32, 33, 34, 35) are made from steel and are corrosion-protected.

6. Protective mesh according to claim 5, characterised in that the wires (11, 12, 13, 14, 15, 16) or wire elements and/or the reinforcement element (31, 32, 33, 34, 35) consists at least in part of high-tensile steel.

7. Protective mesh according to claim 1, characterised in that the wires (11, 12, 13, 14, 15, 16) or wire elements consist at least in part of a high-tensile steel and the reinforcement elements (31, 32, 33, 34, 35) consist of a steel with a lower tensile strength.

8. Protective mesh according to claim 1, characterised in that the reinforcement elements (31, 32, 33, 34, 35) are disposed at regular or irregular distances from each other and are assigned to each of the wire or wire element pairs held flexibly together or to every second or every third wire or wire element pair.

9. Protective mesh according to claim 1, characterised in that the wires (11, 12, 13, 14, 15, 16) or wire elements are curved over or fitted with loops (11 a, 12 a, 13 a, 14 a, 15 a, 16 a) or knots at their ends, while the helical wires or wire elements which are braided together are flexibly connected to each other via these end elements.

10. Protective mesh according to claim 9, characterised in that the reinforcement elements (31, 32, 33, 34, 35) are curved over or fitted with a loop (31 a, 32 a, 33 a, 34 a, 35 a) or a knot at least at one end, while these end elements are flexibly connected with corresponding selvedge loops, or corresponding wire or wire elements are flexibly connected to the end elements (11 a, 12 a; 13 a, 14 a; 15 a, 16 a) which are flexibly connected in pairs.

11. Protective net according to claim 1, characterised in that a slope stabiliser (40) has the wire mesh (10), fixing elements (20) which can be sunk into the ground, with claw plates or similar pressing the mesh onto the soil surface and, at least on the upper side, has a cable (21) holding and stretching the wire mesh (10).