CN115162221A

CN115162221A - Protective net for intercepting rockfall in tunnel

Info

Publication number: CN115162221A
Application number: CN202211024568.8A
Authority: CN
Inventors: 贾志刚; 金磊; 宋涛
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 2016-10-14
Filing date: 2016-10-14
Publication date: 2022-10-11
Also published as: CN107956206A; JP7165291B2; WO2018071097A1; JP2019530819A

Abstract

The present invention relates to a protection net for intercepting rockfall in a railway or highway tunnel, which is composed of para-aramid fibers and does not contain metal filaments. The protective net has high insulation, high heat resistance (160 ℃) and flame retardance, and can be self-extinguished away from fire when ignited.

Description

Protective net for intercepting rockfall in tunnel

The application is a divisional application of Chinese patent application with the application date of 2016, 10 and 14 and the application number of 201610900434.6.

Technical Field

The present invention relates to a protective net having high insulation for intercepting rockfall in a railway or highway tunnel.

Background

Many railway or highway tunnels built decades ago are not lined with concrete and rock formation cracking caused by water erosion, earthquakes, landslides and weathering has increased the risk of rockfall hazards for many years. To prevent this, a steel wire mesh installation is generally performed. The protection net made of high strength steel wires must provide a sufficient load capacity and good fracture or crack resistance. Since some rockfall have a size exceeding 0.5 cubic meter and weigh more than 1 ton, the protection net is required to protect not only passengers, goods, trains/vehicles but also rails or pavements from severe damages due to rockfall.

One problem with steel wire mesh is the inherent high conductivity of steel, the electrostatic effect of which poses a high safety risk to maintenance workers or passing electric trains and automobiles. Therefore, it is important to develop a protective net made of a material having high insulation, high strength and high modulus, such as para-aramid fiber.

Disclosure of Invention

The invention provides a protective net for intercepting rockfall in a railway or highway tunnel, which comprises:

the net body is composed of at least one net rope, and the net rope is knotted to form a plurality of rhombic net meshes;

a net rope, which is a continuous peripheral member as a net boundary; and

a tether, which is a member for connecting a net body to the net rope at a plurality of fixing positions; wherein, the first and the second end of the pipe are connected with each other,

the protective net does not contain metal wires;

the shape of the protective net is rectangular, square, round or triangular;

the length of at least one side of the protective net or the diameter of the protective net is more than 1 meter; and is

The mesh, mesh and tether ropes are each comprised of a plurality of para-aramid yarns, and each yarn has a tensile modulus (modulus) of at least 4000 cN/tex.

Drawings

Fig. 1 shows a conventional knot in a loose form (a), and knitting methods (B) and (C) of a protection net that can be used in the present invention.

Fig. 2 shows the definition of mesh size.

Fig. 3 shows a segment portion (a) of the protection net of the present invention, and one example (B) of connecting both ends of a wire rope.

Fig. 4 shows a front view (a) of a tunnel lined with the protection net of the present invention, and a plan view (B) connecting pairs of the protection net of the present invention for lining/covering the entire length of the tunnel.

Detailed Description

All publications, patent applications, patents, and other references mentioned herein, if not indicated to the contrary, are expressly incorporated herein by reference in their entirety as if fully set forth herein.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

All percentages, parts, ratios, etc. are by weight unless otherwise indicated.

As used herein, the term "consisting of 8230; preparation" is synonymous with "comprising". As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of 8230comprises" excludes any non-specified elements, steps or components. If used in a claim, this phrase shall render the claim closed except for the materials described except for those materials normally associated therewith. When the phrase "consisting of" 82303030, "appears in a clause of the subject matter of the claims and not immediately after the preamble, it defines only the elements described in that clause; no other elements are excluded from the claims as a whole.

The conjunction "consisting essentially of 8230comprises means for defining a composition, method or device which includes materials, steps, features, components or elements other than those literally discussed, provided that such additional materials, steps, features, components or elements do not materially affect the basic and novel characteristics of the claimed invention. The term "consisting essentially of (8230); group (structure)" has a range between "comprising" and "consisting of (8230); group (structure)".

The term "comprising" is intended to include embodiments encompassed by the terms "consisting essentially of (8230); groups (constructs)" and "consisting of (8230)". Similarly, the term "consisting essentially of" 8230 ", group(s)" is intended to encompass embodiments encompassed by the term "consisting of 8230, group(s)".

When an amount, concentration, or other value or parameter is given as a region, preferred region, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all regions formed from any pair of any upper region limit or preferred value and any lower region limit or preferred value, regardless of whether regions are separately disclosed. For example, when a region of "1 to 5" is described, the described region should be understood to include the regions of "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. Where numerical regions are described herein, unless otherwise stated, the regions are intended to include the endpoints of the regions and all integers and fractions within the regions.

When the term "about" is used in describing a numerical value or an endpoint value of a region, the disclosure should be understood to include the specific value or endpoint referred to.

Furthermore, "or" means "or" unless expressly indicated to the contrary, rather than "or" exclusively. For example, condition a "or" B "applies to any of the following conditions: a is true (or present) and B is false (or not present), a is false (or not present) and B is true (or present), and both a and B are true (or present).

"mol%" or "mol%" means mole percent.

In describing and/or claiming the present invention, "homopolymer" refers to a polymer derived from the polymerization of one type of repeat unit. For example, the term "poly (p-phenylene terephthalamide) homopolymer" refers to a polymer consisting essentially of one repeat unit of p-phenylene terephthalamide.

The term "copolymer" as used herein refers to a polymer comprising copolymerized units resulting from the copolymerization of two or more comonomers.

The term "filament" as used herein is defined as a relatively flexible, elongated body having a high aspect ratio, wherein the width refers to the average width of a cross-section taken perpendicular to the length direction. The cross-section of the filaments may be of any shape, for example circular, flat or oval, but is typically circular. The filaments may be solid or hollow in cross-section, preferably solid. The individual fibers may be formed from one filament or from a plurality of filaments. Fibers formed from only one filament are referred to herein as "single-filament" fibers or "monofilame" fibers, and fibers formed from multiple filaments are referred to herein as "multifilament" fibers.

The term "base yarn" as used herein refers to a single yarn composed of a bundle of filaments or fibers obtained from a yarn manufacturer, which may include twisted yarns (twisted yarn) or untwisted yarns. The term "fiber" as used herein is used interchangeably with the term "yarn". The fineness of a yarn is defined as the linear density of the yarn. Linear density is calculated as weight per unit length, typically characterized as "denier" or "dtex"; "denier" is the weight in grams of a 9000 meter yarn, and "dtex" is the weight in grams of a 10,000 meter yarn.

"ply" means an article made by plying (i.e., laying substantially parallel to each other), twisting (twisting), or braiding (weaving) a plurality of yarns as an intermediate step in making a rope. "cord" refers to the final product made by plying, twisting or plaiting a plurality of strands together.

The embodiments of the invention described in the summary of the invention include any other embodiments described herein, which may be combined in any manner, and the description of the variables in these embodiments also applies to the protection net of the invention.

The present invention is described in detail below.

The protection net of the present invention includes: a net body, (b) a net wire rope, and (c) a tether, wherein the net body is composed of at least one net rope, the tether connects the net body with the net wire rope, and the net rope, net wire rope and tether are each composed of a plurality of para-aramid yarns.

The protection net according to the present invention includes a net body composed of at least one mesh rope composed of para-aramid fibers.

The para-aramid fiber is particularly suitable for manufacturing a protective net for intercepting rockfall due to its excellent high tensile strength-to-weight ratio, abrasion resistance, low hygroscopicity, low flammability, and low conductivity.

The term "para-aramid" as used herein refers to poly (p-phenylene terephthalamide) homopolymers and poly (p-phenylene terephthalamide) copolymers. Poly (p-phenylene terephthalamide) homopolymer is prepared by mole-for-mole polymerization of p-phenylene diamine (PPD) and Terephthaloyl Chloride (TCL). In addition, poly (p-phenylene terephthalamide) copolymers are obtained by adding up to 10 mole percent of other diamines and p-phenylene diamines and up to 10 mole percent of other diacid chlorides and terephthaloyl chloride, provided that the other diamines and diacid chlorides have no reactive groups that interfere with the polymerization reaction. Examples of diamines other than p-phenylenediamine include, but are not limited to, m-phenylenediamine, or 3,4 '-diaminodiphenyl ether (3, 4' -DAPE). Examples of diacid chlorides in addition to terephthaloyl chloride include, but are not limited to, isophthaloyl chloride, 2, 6-naphthaloyl chloride, chloroterephthaloyl chloride, or dichloroterephthaloyl chloride.

The para-aramid can be spun into fibers by solution spinning from a solution containing the polymer or copolymer in a polymerization solvent or other solvent. Fiber spinning can be accomplished by means of dry spinning, wet spinning or dry-jet wet spinning (also known as air-gap spinning) through a multi-hole spinneret to produce multi-filament fibers as known in the art. The spun multifilament fiber can then be neutralized, washed, dried, or heat treated as needed using conventional techniques to obtain a stable and useful fiber.

Para-aramid fibers (i.e., base yarn) are commercially available, for example, from Teijin (Japan)

From Dupont Namule, inc. (hereinafter referred to as Dupont for short)

From Kolon Industries, inc

Preferably, the para-aramid fibers used have a linear density of at least 220 dtex, a specific strength at break of 200cN/tex, a tensile modulus of at least 4000cN/tex and an elongation at break of 5% or less.

Breaking strength (cN) of a yarn, which is the maximum force a yarn can withstand before breaking, can be measured according to ASTM D7269. Specific breaking tenacity (breaking tenacity) is calculated by dividing the breaking tenacity by the linear density of the yarn (in tex).

In one embodiment, in the protection net of the present invention, the mesh ropes, net ropes, and tethers are composed of para-aramid yarns having a linear density of about 220 to 3,300 dtex, preferably about 660 to 2,500 dtex, more preferably about 1,100 to 1,800 dtex.

In another embodiment, in the protection net of the invention, the mesh ropes, the net ropes, and the tether ropes are composed of para-aramid yarns, and each has a tensile modulus of at least about 4000cN/tex, or preferably about 4500cN/tex, or more preferably about 4800 cN/tex.

Net mesh rope

In the invention, the net body is composed of at least one net mesh rope, and the net mesh rope is knotted to form a plurality of rhombic net meshes. When a diamond mesh is pulled apart to have 4 interior angles of about 90 degrees, the mesh is effectively square.

The mesh rope may be made from a plurality of para-aramid yarns according to conventional textile techniques such as twisting, braiding, stranding, plying, or combinations thereof. For example, a mesh rope may be constructed by braiding a plurality of strands, which are then made by twisting more than one yarn. However, when a rope is built up by twisting, it is important that the strands are twisted in a balanced manner (balanced twist), which ensures that a rope with a high maximum load (load force) is manufactured. For example, balancing twist generally involves two steps: firstly, combining at least two yarns, twisting (primarily twisting) in a first direction, wherein filaments in the yarns run parallel to the running direction of the yarns to obtain plied yarns; second, at least two strands are then combined and twisted (double twisted) in a second direction opposite to the first direction to form the rope. The twist of the yarn and the strands is expressed in terms of twist per meter (tpm). Preferably, the twist of the yarn and the strands is 50-250tpm. The twisting direction can be that the S twist is obtained by rotating along the right hand direction, or the Z twist is obtained by rotating along the left hand direction.

In one embodiment, in the protection net of the present invention, the mesh ropes are composed by braiding at least 4 twisted or untwisted yarns or strands on a braiding machine. Depending on the particular type of knitting machine used, the number of yarns or strands used for braiding is preferably an even number, e.g., 4, 6, 8, 10, 12 or more. Note that braided ropes may contain a core yarn composed of a plurality of yarns or strands.

As the number of yarns per rope increases, the equivalent diameter of the rope and the maximum load of the rope generally also increases, provided that the ropes are composed of the same yarns and are constructed in the same manner. One skilled in the art can select the appropriate number of yarns per rope and combine them together by twisting, braiding, plying, or a combination thereof. According to the method of construction of the rope, the maximum load of the rope is not equal to the direct sum of the breaking forces of each yarn therein, which is generally observed to be about 50-90% of this value.

The term "equivalent diameter" as used herein refers to the diameter of a circumscribed circle that will enclose all of the fibers or strands. This is therefore a measure of the maximum cross-section of the yarn or rope.

Mesh cords suitable for use in the present invention have an equivalent diameter of at least 0.3mm, or 1mm, or 3mm, allowing for ease of tying knots by hand or on conventional equipment; and no greater than 10mm, or 8mm, or 6mm. In order to obtain a protective net with a suitable load capacity, the mesh ropes of the invention have a maximum load of at least about 1,000n, or 3,000n, or 5,000n, or 7,000n, or 10,000n, or 12,000n.

In one embodiment, in the protection net of the present invention, the equivalent diameter of the mesh ropes is about 0.3 to 10mm, or 1 to 8mm, or 3 to 6mm.

In a further embodiment, in the protection net of the invention, the maximum load of the mesh ropes is at least about 1,000n, or 3,000n, or 5,000n, or 7,000n, or 10,000n, or 12,000n.

In some embodiments of the invention, the mesh cord is produced by braiding a plurality of plied para-aramid base yarns such as

K29 (1670 dtex, breaking strength of each raw yarn is 338N); the calculated values of the equivalent diameter (mm) and the maximum load (N) of each rope, according to the number of its yarns, are listed in table 1 for reference.

TABLE 1

* The equivalent diameter and maximum load data of a rope with 72 total yarns are directly obtained by measurement and test. ^a The equivalent diameter of each rope is calculated proportionally to the number of total yarns with respect to the equivalent diameter of the rope with 72 yarns.

^b The maximum load per rope is calculated from the number of total yarns in proportion to the maximum load of a rope with 72 yarns.

In one embodiment, in the protection net of the present invention, the total number of para-aramid yarns per mesh rope is in the range of 4 to 144, wherein the linear density of the para-aramid yarns is 1670 dtex (1500D).

The mesh rope is also commercially available from, for example, shanghai Xin Teh rope Co., ltd and Zhejiang four brother rope industry Co., ltd in the form of 12 strands of single layer braided rope, diamond braided rope and core rope, with a variety of diameters and spool sizes available.

Methods for producing knotted netting are well known in the art. In the present invention, the mesh body can be manufactured by hand or a conventional net-weaving machine in a conventional manner. As shown in fig. 1 (a), for example, the mesh cord may be knotted with a sheet band knot (A1 and A2), a double knot (A3), or a flat knot (A4) of a Z-type or S-type; and a single-line or two-line method is adopted to weave a net body (see fig. 1 (B) and (C)). For a net formed by the single strand process (fig. 1 (B)), the direction of the stitching of the mesh strands is perpendicular to the direction of growth (or length direction, L) of the net, i.e. as indicated by the arrow labeled "L". In contrast, a two-wire method (fig. 1 (C)) is used, in which the direction of the braiding of the mesh strands is parallel to the direction of growth of the net.

Whichever knot is made, the strands of the mesh cord will remain locked at the point of intersection with each other to maintain the predetermined size of the mesh, mesh size (d). The mesh size of the protection net of the invention can be represented by the distance between the centers of 2 adjacent knots of a diamond mesh, also called half mesh to knot distance (half mesh to knot); the full mesh knot pitch (full mesh to knot) is defined as the distance between the centers of two opposite knots of the stretched mesh, equal to 2d (see fig. 2). Since the diamond mesh can be pulled apart and made into a square, the mesh size can also be expressed as d x d.

Nets with smaller mesh sizes are able to intercept smaller rocks and have higher loadings provided the mesh ropes used are the same. Although this will also drive the net weight and production costs up.

The main factors determining the loading capacity of the protective net of the invention are the equivalent diameter of the mesh rope and the mesh size thereof. For the use according to the invention, the loading of the mesh is at least 0.3 tonnes, preferably at least 0.5 tonnes, and more preferably at least 1.0 tonnes, as measured according to the UNI11437-2012 method. For a given mesh rope, one skilled in the art can select the appropriate size of the mesh ropes and tethers and adjust the mesh size to produce a protective net that meets the load requirements of a particular tunnel site.

The relationship between the load amount of the protection net and the mesh size with respect to the equivalent diameter of the mesh rope is shown in table 2.

TABLE 2

^a The loading of each net was calculated based on the measured loading of nets made with mesh ropes having an equivalent diameter of 5mm and a mesh size of 60mm.

^b The net weight of each net was only estimated.

In one embodiment of the present invention, the mesh size (d) of the protection net is in the range of about 30mm to about 100 mm.

As shown in fig. 3 (a), the protection net 100 of the present invention uses the net ropes 20 to define the peripheral flexible boundary thereof and increase the strength and durability of the net body 10. The wire rope 20 is typically a continuous piece of rope that is threaded through the edge mesh, and the two ends are connected by folding the ends back to form an interlocking loop and then tying them together (as shown in fig. 3 (B)). A suitable mesh rope 20 is comprised of para-aramid fibers as described previously and has an equivalent diameter of about 1.5 to 2 times the equivalent diameter of the mesh rope. The net body 10 may be fastened to the net rope 20 by a tether 30 in any conventional manner. For example, the tethers are threaded through each edge mesh of the net body and tied around the net rope 20 with clove knots in an equally spaced manner. The tether 30 is comprised of para-aramid fibers as previously described. Suitable equivalent diameter ratios of the tether 30 to the mesh cord for the purposes of the present invention are about 1/5 to 1/2. For example, the protection net of the present invention is composed of mesh ropes having an equivalent diameter of about 5mm, preferably, the equivalent diameter of the mesh ropes is about 7.5mm to about 10mm, and the equivalent diameter of the tethers is about 1mm to about 2.5mm.

The protection net may be in the shape of a rectangle, square, circle, or triangle according to the requirements of a specific tunnel site. Preferably, the protection net of the present invention is a rectangular net or a square net. The size of the protection net of the present invention is not particularly limited, and generally, at least one side of the protection net has a length or diameter greater than 1 meter. For example, the length and width of a rectangular or square mesh may each independently vary between 1 meter and 10 meters.

Instead of customizing a large net to cover the entire length of the tunnel and the full span of the arched tunnel roof, for ease of transport and installation, multiple pairs of the same size nets may be attached together by stitching with a stitching rope during installation. The length (L) or width (W) of the web preferably covers at least the centerline from the roof of the arch tunnel and may extend to about 0.5-2 meters above the sidewalls as shown in fig. 4 (a). Since the length of the tunnel may vary, pairs of the protection net of the present invention of the same size, e.g., 10m x 6m, may be fixed together on the roof of the arched tunnel by a conventional method known to the skilled person to cover the entire length of the tunnel. Fig. 4 (B) is a plan view showing one way of connecting a plurality of protection nets. The protective mesh is preferably fastened to the tunnel vault and a part of the side wall area by means of clamping members and/or anchor rods with fibre protective members, such as anchor pads. The stitched rope consists of para-aramid fibers as described previously. Suitable suture strands have an equivalent diameter ratio to the mesh strands of about 1.2 to 2.2.

The protective net of the invention is completely composed of the para-aramid yarn, so that the weight of the protective net is obviously reduced and the possibility of draping is reduced compared with a steel wire net. Furthermore, unlike any other net composed of synthetic fibers such as polyamide (PA 6, PA66, or the like) or ultra-high molecular weight polyethylene (UHMWPE), the protective net of the present invention composed of para-aramid yarns has high electrical insulation, high heat resistance (160 ℃) and flame retardancy, and also self-extinguishes from a fire when ignited. Due to the polymeric nature of the para-aramid, the webs of the present invention are slightly sensitive to UV light. For the special purpose of the invention in the tunnel, the probability of the deterioration of the protective net due to UV light is greatly reduced.

In one embodiment, the load of the protection net of the present invention is at least 0.3 ton, or at least 0.5 ton, at least 1.0 ton.

In another embodiment, the protection net of the present invention satisfies UL 94V-0 rating and has a resistivity of 10 ⁹ Omega or greater.

Optionally, a suitable coating may be applied to the mesh of the present invention to prevent abrasion and damage from UV light, so long as the loading of the mesh can be maintained. Suitable coating compositions comprise at least 10-50% of a Polyurethane (PU) resin, a carrier, and optionally uv light absorbers, extenders, plasticizers and/or dyes.

The polyurethane resin is typically obtained by reacting an isocyanate-containing component and a hydroxyl-containing component. The polyurethane resin may be classified into acrylic polyurethane, alkyd polyurethane, polyester polyurethane, polyether polyurethane, epoxy polyurethane, and the like, depending on the hydroxyl group-containing component. The polyurethane resin is preferably a polyester polyurethane, and more preferably a polyester aliphatic polyurethane.

The carrier may be trichloroethane, methylene chloride, perchloroethylene, water, xylene, mixed xylenes (xylol), toluene, mineral spirits such as naphtha, or mixtures thereof. Preferably, the carrier is water.

The coating composition may also optionally include an Ultraviolet (UV) light absorber to help extend the life of the coated mesh by preventing the fibers from degrading due to exposure to sunlight. A variety of UV light absorbers such as benzotriazoles and benzophenones can be used and are compatible with the polyurethane resin of the coating composition. Presently preferred UV light absorbers are the benzotriazoles, for example,

available from BASF AG, germany.

The coating compositionAn extender may optionally be included. Suitable extenders are inert, durable, miscible and abrasion resistant, compatible with the polyurethane resin used. The extender may also be a filler having the same properties. Examples of suitable extenders include silicates, glass spheres, carbon black, or any other proprietary extender. The presently preferred extender is carbon black, which is available under the trade name carbon black

(Degussa AG, germany).

The coating composition may also optionally include a plasticizer to increase the flexibility and durability of the coated web. Suitable plasticizers include esters selected from the group consisting of phthalates, benzoates, adipates, and sebacates; polyols such as ethylene glycol and derivatives thereof; and castor oil. Preferred plasticizers include butyl octyl phthalate, di (2-ethylhexyl) phthalate, dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, diisononyl phthalate, dipropylene glycol dibenzoate and diethylene glycol dibenzoate. The presently preferred extenders are benzoates available from Eastman Chemical Company, USA under the trade name benzoic acid

Are commercially available.

In one embodiment, the coating composition is an aqueous polyurethane dispersion. In another embodiment, the aqueous polyurethane dispersion comprises at least 10-50% of a polyurethane resin, wherein the polyurethane resin is a polyesteraliphatic polyurethane.

Suitable PU coating compositions are commercially available, for example, from aqueous polyurethane dispersions available under the trade name ICO-THANE from I-Coats n.v. (belgium).

The method of preparing the coated protection net includes: i) Providing a suitable concentration of the coating composition, ii) applying the coating composition to the mesh for a sufficient time to allow the coating composition to penetrate into the fibers of the mesh, iii) optionally, removing excess coating composition, and iv) drying the wet web. The coating composition may be applied to the protective mesh of the present invention by dipping, immersion, brushing, rolling, or spraying. Depending on the application method used, the concentration of the coating composition can be adjusted by known methods by the person skilled in the art, for example by dilution with a suitable carrier. The wet web is laid flat or hung on a drying rack and dried by heating at ambient temperature and/or in an oven at 50-80 ℃ for 60-400 minutes. Removal of excess coating composition can be accomplished by whipping the wet web, passing the wet web over two opposing rolls, passing the wet web over a series of vented rolls, or by a variety of other methods known to those skilled in the art.

After drying, the content of the polyurethane coating in the coated protection net is preferably about 5 to 15% by weight based on the total weight of the coated protection net.

In one embodiment, the protection net of the present invention further comprises a polyurethane coating. In another embodiment, in the protection net of the present invention, the content of the polyurethane coating is about 5 to 15% by weight, based on the total weight of the coated protection net.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Accordingly, the following examples should be construed as merely illustrative, and not limitative of the disclosure in any way whatsoever.

Examples

Material

Raw yarn: para-aramid K29AP fiber, 1670 dtex, 1000 filaments/yarn, breaking tenacity 338N; tensile modulus 4900cN/tex, elongation at break 3.6%, obtained from DuPont.

Mesh rope: (a) Twisting 4-6 para-aramid base yarns on a braiding machine (S or Z twist, 60 tpm) to obtain para-aramid strands; (b) 12 para-aramid strands were braided to give a mesh rope with an equivalent diameter of about 3-5 mm.

A net rope: (a) Twisting 8-12 para-aramid base yarns on a braiding machine (S or Z twist, 60 tpm) to obtain para-aramid strands; (b) 12 para-aramid strands were braided to obtain a mesh rope having an equivalent diameter of about 8-10 mm.

Tying a rope: (a) Plying 3-4 pieces of para-aramid raw yarns on a knitting machine to obtain para-aramid plied yarns; (b) 6 para-aramid strands were braided to give a tether with an equivalent diameter of about 1-1.5 mm.

PU coating composition: the PU coating composition was prepared by diluting 30 parts by weight of an aqueous polyester aliphatic polyurethane dispersion (ICO-THANE 10, sold by I-Coats n.v. (belgium)) with 70 parts by weight of water.

Coating test: 3 greige yarns (63 cm long) were weighed before coating to obtain a pre-weight (W) ₀ ). The yarn was immersed in the PU coating composition for 10 minutes at room temperature, then removed from the container, flat-dried at room temperature, and weighed to obtain a coated sample weight (W) ₁ ). The content of the dope (Δ W) was calculated from the formula shown below:

ΔW％＝[(W ₁ -W ₀ )/W ₁ ]×100

TABLE 3

The data in table 3 show that immersion in the aqueous polyurethane dispersion for 10 minutes at room temperature gives an average coating content in the coated yarn of about 10.6%.

Abrasion resistance test: the breaking strength (S) of each sample was measured and recorded ₀ ) The samples included 6 coated yarns (CY 1-CY 6) and 6 uncoated yarns (Y1-Y6). The coated yarn was made according to the method in the coating test described above.

Each yarn (55 cm long) was subjected to a rubbing treatment using a yarn rubbing tester (model SM-II, manufactured by beiying Science and Technology Development co. The yarns were crossed with a load of 2.5kg and the ends of the yarns were secured in 2 anchorsThe stator is arranged. As the yarn holder moves back and forth at a frequency of 1 second per cycle, the yarn sample is allowed to rub against itself. After 600 cycles, the samples were removed from the friction tester, and the breaking strength (S) of each sample was measured and recorded ₁ )。

Loss of breaking Strength (Δ S): the breaking strength loss of the rope sample after the rubbing treatment was calculated by the following formula:

ΔS％＝[(S ₁ -S ₀ )/S ₀ ]×100

TABLE 4

The abrasion resistance of the yarn was evaluated according to the magnitude of the breaking strength loss. As can be seen from the data in table 4, the PU coated yarn has less loss of breaking strength and therefore higher abrasion resistance than the uncoated yarn.

Resistivity testing: five mesh rope samples (10 cm long, 5mm equivalent diameter) were tested for resistance using a resistance device megger according to IEC60468, 1 st edition, 08-15-1990 methods. The data are presented in the table below, demonstrating the high resistivity of the mesh rope.

TABLE 5

Maximum load test: five mesh rope samples (10 cm long, 5mm equivalent diameter) were tested for maximum load on an Instron 9995 universal testing machine. The maximum load of the mesh rope was determined according to ASTM D7269. The data are presented in the table below, and the average maximum load of the tested mesh ropes of 5mm equivalent diameter was 16641N.

TABLE 6

Flame retardancy test (UL 94): according to the method: five mesh rope samples (10 cm long, 5mm equivalent diameter) were tested "Tests for flexibility of Plastic Materials, UL94", underwriter's Laboratory Bulletin 94. Based on the results of 10 combustion tests, a V-0 rating was obtained.

Examples 1-3 web manufacture

Using mesh ropes, net ropes and tethers composed of para-aramid fibers having equivalent diameters listed in table 7, a 2.5m × 2.5m net was prepared. First, the mesh rope was knotted flat by hand in a single-thread method, and its mesh size was 60mm. Then, the net body is tied and fixed on the net rope by a rope with clove knots.

The web is weighed (W) ₀ ) And immersed in a container containing about 50 liters of the PU coating composition at room temperature for 10 minutes. After removal from the container, the web was allowed to dry overnight at ambient temperature to allow the PU coating to cure and weighed again (W) ₁ ). The PU coating content of the coated web was calculated from the formula shown below:

ΔW％＝[(W ₁ -W ₀ )/W ₁ ]×100

TABLE 7

Load capacity testing: the net sample was hooked on the frame of a fracture tester, which is a 1000KN fracture test equipment (manufactured by mitsunwa ott mechanical equipment limited, chengdu, china). The loading of the web was determined by causing a maximum force of no more than 5 broken meshes.

TABLE 8

While the invention has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions are possible without departing in any way from the spirit of the present invention. Accordingly, while modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims.

Claims

1. A protection net for intercepting rockfall in a railway or highway tunnel, comprising:

the net body is composed of at least one net mesh rope, and the net mesh rope is knotted to form a plurality of rhombic net meshes;

a net rope, which is a continuous peripheral member as a net boundary;

a tether, which is a member for connecting a net body to the net rope at a plurality of fixing positions; and

a polyurethane coating, and the content of the polyurethane coating is 5-15 wt% of the total weight of the coated protection net;

wherein the content of the first and second substances,

the protective net does not contain metal wires;

the shape of the protective net is rectangular, square, round or triangular;

The mesh, mesh and tether ropes are each comprised of a plurality of para-aramid yarns, and each yarn has a tensile modulus of at least 4000 cN/tex.

2. The protection net according to claim 1, wherein the mesh size of the protection net is in the range of 30mm to 100mm, the mesh size being the distance between the centers of 2 adjacent knots of a diamond-shaped mesh.

3. The protection net according to claim 1, wherein the mesh ropes have an equivalent diameter of 0.3mm to 10mm.

4. A protection net according to claim 1, wherein the equivalent diameter ratio of the net ropes to the mesh ropes is 1.5-2.

5. The protection net according to claim 1, wherein the equivalent diameter ratio of the tether to the mesh rope is 1/5 to 1/2.

6. The protection net according to claim 1, wherein the mesh ropes are knotted in Z or S type dead knots, double dead knots or flat knots to form the net body.

7. A protection net according to claim 1, wherein the tethers pass through edge meshes of the net body and are tied around the wire rope in an equally spaced manner.

8. A protection net according to claim 1, with a load of at least 0.3 tons.

9. The protective netting of claim 1, which conforms to a UL 94V-0 rating and has a resistivity of 10 ⁹ Omega or greater.