WO2018071097A1 - Protective net for catching falling rocks in tunnels - Google Patents
Protective net for catching falling rocks in tunnels Download PDFInfo
- Publication number
- WO2018071097A1 WO2018071097A1 PCT/US2017/048140 US2017048140W WO2018071097A1 WO 2018071097 A1 WO2018071097 A1 WO 2018071097A1 US 2017048140 W US2017048140 W US 2017048140W WO 2018071097 A1 WO2018071097 A1 WO 2018071097A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- net
- rope
- protective net
- protective
- equivalent diameter
- Prior art date
Links
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- 229920000271 Kevlar® Polymers 0.000 description 2
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- MSWAXXJAPIGEGZ-UHFFFAOYSA-N 2-chlorobenzene-1,4-dicarbonyl chloride Chemical compound ClC(=O)C1=CC=C(C(Cl)=O)C(Cl)=C1 MSWAXXJAPIGEGZ-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01F—ADDITIONAL WORK, SUCH AS EQUIPPING ROADS OR THE CONSTRUCTION OF PLATFORMS, HELICOPTER LANDING STAGES, SIGNS, SNOW FENCES, OR THE LIKE
- E01F7/00—Devices affording protection against snow, sand drifts, side-wind effects, snowslides, avalanches or falling rocks; Anti-dazzle arrangements ; Sight-screens for roads, e.g. to mask accident site
- E01F7/04—Devices affording protection against snowslides, avalanches or falling rocks, e.g. avalanche preventing structures, galleries
- E01F7/045—Devices specially adapted for protecting against falling rocks, e.g. galleries, nets, rock traps
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D19/00—Provisional protective covers for working space
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/23—Dune restoration or creation; Cliff stabilisation
Definitions
- This invention relates to a protective net having high electrical insulating property for catching falling rocks in a railway or roadway tunnel.
- This invention provides a protective net for catching falling rocks in a railway or roadway tunnel, comprising:
- a net body composed of at least one net rope that is knotted to form a plurality of meshes in rhombic shape
- tie rope that is a member for attaching the net body to the fame rope at a plurality of fixed positions
- the net is free of metal wire
- the shape of the net is rectangular, square, circle or triangular
- each of the net rope, frame rope and tie rope is composed of a plurality of p-aramid yarns, and each yarn has a tensile modulus of at least 4000 cN/tex.
- FIG. 1 shows common knots in loose form (A), and knotting methods (B) and (C) that may be used for the protective net of the present invention.
- FIG. 2 shows the mesh size definitions.
- FIG. 3 shows a fragment section of the protective net of the present invention (A), and one example of connecting two ends of the frame rope (B).
- FIG. 4 shows a front view of a tunnel lined with the protective net of the present invention (A), and a flat view of joining multiple pairs of the present nets for lining/covering a full length tunnel (B).
- the term “produced from” is synonymous to “comprising”.
- the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof are intended to cover a non-exclusive inclusion.
- 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.
- transitional phrase consisting essentially of is used to define a composition, method or apparatus that includes materials, steps, features, components, or elements, in addition to those literally discussed, provided that these additional materials, steps features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention.
- Mole% or “mol%” refers to mole percent.
- homopolymer refers to a polymer derived from polymerization of one species of repeating unit.
- poly(p-phenylene terephthal amide) homopolymer refers to a polymer consisting essentially one species of repeat unit of /?-phenylene terephthal amide.
- copolymer refers to polymers comprising copolymerized units resulting from copolymerization of two or more comonomers.
- filament is defined as a relatively flexible, elongate body having a high length to width ratio, wherein the width refers to the average width of the cross- sectional area perpendicular to the longitudinal direction.
- the filament cross section can be any shape such as circular, flat or oblong but is typically circular.
- the filament cross section can be solid or hollow, preferably, solid.
- a single fiber may be formed from just one filament or from multiple filaments.
- a fiber formed from just one filament is referred to herein as either a "single- filament” fiber or a "monofilament” fiber, and a fiber formed from a plurality of filaments is referred to herein as a "multifilament” fiber.
- base yarn refers to a single yarn consisting of bundle of filaments or fibers as received from a yarn manufacturer, which may include twisted yarn or yarn with no twist.
- fiber is used interchangeably with the term “yarn.”
- the fineness of a yarn is defined as the yarn's linear density.
- the linear density is calculated as weight per length and is usually characterized as a “denier” or “dtex”; “denier” is the weight in gram of 9000 meters of a yarn, and “dtex” is the weight in gram of 10,000 meters of a yarn.
- “Strand” refers to a product obtained by plying (i.e. laying largely in parallel to each other), twisting, or braiding multiple yarns as an intermediate step in forming a rope.
- “Rope” refers to the final product obtained by plying, twisting, or braiding multiple strands together.
- the protective net of the present invention comprises (a) a net body, (b) a frame rope, and (c) a tie rope, where the net body is composed of at least one net rope, the tie rope attaches the net body to the frame rope, and each of the net rope, frame rope and tie rope are composed of a plurality of p-aramid yarns.
- the protective net of the present invention comprises a net body composed of at least one net rope, which is composed of p-aramid fibers.
- the p-aramid fibers are suited especially for producing protective nets used for catching falling rocks due to their excellent high tensile strength-to-weight ratio, resistance to wear and abrasion, a low absorption of humidity, low flammability, and a low electrical conductivity.
- /?-aramid refers to poly(p-phenylene terephthalamide) homopolymers and poly(p-phenylene terephthalamide) copolymers.
- Poly(p-phenylene terephthalamide) homopolymer is resulting from mole-for-mole polymerization of /?-phenylene diamine (PPD) and terephthaloyl chloride (TCI).
- poly(p-phenylene terephthalamide) copolymers are resulting from incorporation of as much as 10 mol% of other diamines with the /?-phenylene diamine and of as much as 10 mol% of other diacyl chlorides with the terephthaloyl chloride, provided that the other diamines and diacyl chlorides have no reactive groups which interfere with the polymerization reaction.
- diamines other than /?-phenylene diamine include but not limited to w-phenylene diamine, or 3,4'-diaminodiphenylether (3,4'- DAPE).
- diacyl chlorides other than terephthaloyl chloride include but not limited to isophthaloyl chloride, 2,6-naphthaloyl chloride, chloroterephthaloyl chloride, or dichloroterephthaloyl chloride.
- the p-aramid described above can be spun into fibers via solution spinning, using a solution of the polymer or copolymer in either the polymerization solvent or another solvent for the polymer or copolymer.
- Fiber spinning can be accomplished through a multi-hole spinneret by dry spinning, wet spinning, or dry -jet wet spinning (also known as air-gap spinning) to create a multifilament fiber as is known in the art.
- the multifilament fiber after spinning can then be treated to neutralize, washed, dried, or heat treated the fibers as needed using conventional techniques to make stable and useful fibers.
- the p-aramid fibers are commercially available, for example, TWARON ® from Teijin (Japan), KEVLAR ® from E. I. Du Pont De Nemours and Company (abbreviated as DuPont hereunder), HERACRON ® from Kolon Industries, Inc.
- the p-aramid fiber has a linear density of at least 220 dtex, a breaking tenacity of 200 cN/tex, a tensile modulus of at least 4,000 cN/tex, and an elongation at break of 5% or less are used.
- the breaking strength in unit of cN of a yarn may be measured according to the ASTM D7269 method, where the breaking strength is the maximum force that the yarn can withstand before breakage. Breaking tenacity is calculated by dividing the breaking strength over the linear density (in unit of tex) of the yarn.
- the net rope, frame rope and tie rope are composed of p-aramid yarn having a linear density of about 220-3,300 dtex, preferably about 660-2,500 dtex, more preferably about 1, 100-1,800 dtex.
- the net rope, frame rope and tie rope are composed of p-aramid yarns and each have a tensile modulus of at least about 4000 cN/tex, or preferably about 4500 cN/tex, or more preferably about 4800 cN/tex.
- the net body composed of at least one net rope that is knotted to form a plurality of meshes in rhombic shape.
- a rhombic mesh is pulled open to have the 4 corners of about 90°, then the mesh is actually in square shape.
- a net rope may be produced from a plurality of the p-aramid yarns according to conventional textile techniques such as twisting, braiding, stranding, plying, or a combination thereof.
- a net rope may be constructed by braiding a plurality of strands that were formed by twisting more than one yarn.
- twisting it is however essential that the strands are twisted in a balanced manner (balanced twist) which ensures to produce a high load force rope.
- balanced twist generally involves 2 steps: first, at least two yarns are combined and twisted in a first direction with which the filaments in the yarns run parallel to the running direction of the yarns to obtain a strand; second, at least two strands may be then combined and twisted with a second direction opposite to the first direction to form a rope.
- the twist level of the yarns and strands is described by number of twists per meter (tpm).
- tpm twists per meter
- the twist level of the yarns and strands is 50-250 tpm.
- the twist direction can be right-handed turn to yield an S-twist, or left-handed turn to yield a Z-twist.
- the net rope is constructed by braiding of at least 4 strands of twisted or untwisted yarns or strands on a braider.
- the number of yarns or strands for braiding is preferably an even number, such as 4, 6, 8, 10, 12, or more.
- the braided rope may comprise a core yarn composed of a plurality of yarns or strands.
- the equivalent diameter of the rope generally increases and the load force of the rope increases as well, provided that the rope is composed of the same yarns and constructed the same way.
- One skilled in the art can select a suitable number of yarns per rope and have them twisted, braided, plied together; or combinations thereof.
- the breaking strength of each yarn in the rope may not be summed directly as the load force of the rope and about 50-90% of the sum is commonly observed.
- the term "equivalent diameter” refers to the diameter of a circumscribed circle that will enclose all the fibers or strands. Therefore, it's the largest cross-sectional measurement of a yarn or a rope.
- suitable net rope of the invention has an equivalent diameter of at least 0.3 mm, or 1 mm, or 3 mm; and no more than 10 mm, or 8 mm, or 6 mm.
- the net rope of the invention has a load force of at least about 1,000N, or 3,000N, or 5,000N, or 7,000N, or 10,000N, or 12,000N.
- the net rope in the protective net of the present invention, has an equivalent diameter of about 0.3-10 mm, or 1-8 mm, or 3-6 mm.
- the net rope has a load force of at least about 1,000N, or 3,000N, or 5,000N, or 7,000N, or 10,000N, or 12,000N.
- the net rope is formed by braiding of multiple plied p-aramid base yarns such as Kevlar ® K29 (1670 dtex, each base yarn has a breaking strength 338N); based on the number of yarns per rope, the calculated equivalent diameter (mm) and load force (N) are listed in Table 1 for reference.
- each rope is calculated proportionally based on its total number of yarns relative to that of the rope having 72 yarns.
- the load force of each rope is calculated proportionally based on its total number of yarns relative to that of the rope having 72 yarns.
- the total number of p- aramid yarns per one net rope ranges from 4 to 144, where the p-aramid yarn has a linear density of 1670 dtex (1500 D).
- the net rope is also commercially available in 12 strand single braid rope, diamond braid rope, and core rope from, for example, Shanghai Xinhuang Rope Braiding Company and Zhejiang Four Brothers Rope Company, Ltd. with a wide variety of diameters and spool sizes are available.
- the net body may be fabricated by hand or a conventional netting machine in a customary manner.
- the net rope may be knotted with Z or S type sheet bend knot (Al and A2), sheet bend double knot (A3), or square knot (A4); and employed a single strand or a double-strand method to form the net body (see FIG.1(B) and (C)).
- the weaving direction of the net rope is perpendicular to the net advancing direction (or lengthwise direction) i.e. as indicated by the arrow labelled with "L.”
- the double-strand method FIG. 1(C)
- the weaving direction of the net ropes are parallel to the net advancing direction.
- mesh size of the present net can be represented by the distance between the centers of the 2 adjacent knots of a rhombic mesh, also known as half mesh knot to knot (hmkk); full mesh knot (fmkk) is defined as the distance between the centers of 2 opposite knots of a stretched mesh that equals 2d (see Figure 2).
- hmkk half mesh knot to knot
- fmkk full mesh knot
- the mesh size may also be represented by d x d.
- Nets having smaller mesh size can catch smaller rocks and have higher load capacity provided that the net ropes used thereof are the same. Although, it will also drive the net weight and production cost higher.
- Main factors contribute to the load capacity of the present net are the equivalent diameter of the net rope used thereof and the mesh size.
- the protective net has a bearing capacity of at least 0.3 Ton, preferably at least 0.5 Ton, and more preferably at least 1.0 Ton as measured according to an UNI11437-2012 method.
- a give net rope one skilled artisan may choose the suitable sized frame rope and tie rope as well as adjust the mesh size to manufacture a protective net to meet the load requirement for a particular tunnel site.
- the bearing capacity of each net was calculated based the measured bearing capacity for the net constructed with a net rope having an equivalent diameter of 5 mm and a mesh size of 60 mm.
- the net weight of each net was estimated for the weight of the net body only.
- the protective net has a mesh size (d) in the range of from about 30 mm to about 100 mm.
- the present protective net 100 uses a frame rope 20 to define its peripheral flexible borders and add strength and durability to the net body 10.
- the frame rope 20 is generally a continuous rope that lacing through the edge meshes, and the two ends of it are connected by folding each end backward to form interlocked loops, and then tying knot as shown in FIG. 3(B).
- Suitable frame rope 20 is composed of p-aramid fibers as described previously, and has an equivalent diameter of about 1.5-2 times of the equivalent diameter of the net rope.
- the net body 10 may be fastened to the frame rope 20 by a tie rope 30 in any of the usual manners.
- the tie rope 30 is composed of p-aramid fibers as described previously.
- the equivalent diameter ratio of a suitable tie rope 30 to the net rope is about 1/5 to 1/2.
- the present protective net is composed of a net rope having an equivalent diameter of about 5 mm, then a frame rope has an equivalent diameter of from about 7.5 mm to about 10 mm and a tie rope has an equivalent diameter of from about 1 mm to about 2.5 mm are preferred.
- the protective net may be rectangular, square, round, or triangular in shape according to the specific tunnel site' s requirements.
- the present protective net is a rectangular net or a square net.
- the size of the present protective net has no particular limitation, and typically the length of at least one edge or the diameter of the net is greater than 1 meter.
- the length and width of a rectangular net or a square net may each independently vary from 1 meter to 10 meters.
- the length (L) or width (W) of a single net covers at least from the center line of the arched tunnel ceiling and may be extended to about 0.5-2 meters of the sidewall as illustrated in FIG. 4 (A). Since the length of a tunnel may vary, multiple pairs of the present protective nets of the same dimension, e.g., 10 m x 6 m (L x W) can be jointly fixed on the arched tunnel ceiling by conventional methods known to skilled artisans to cover the full length of the tunnel.
- the protective net preferably is fastened to the tunnel arched ceiling and a portion of the sidewall areas by means of clamping elements and/or rod anchors with fiber-protective elements such as anchoring plates.
- the sewing rope is composed of p-aramid fibers as described previously. The equivalent diameter ratio of a suitable sewing rope to the net rope is about 1.2 to 2.2.
- the present protective net composed of p-aramid yarns exclusively results in not only a considerable weight reduction but also lowered draping possibilities as compared to the steel wire nets. Furthermore, unlike any other nets composed synthetic fibers such as polyamide (PA6, PA66, or the like) or ultra-high molecular weight polyethylene (UHMWPE), the present net composed of p-aramid yarns has high electrical insulation, high heat tolerance (160°C), and is flame resistant, also self-extinguishes when ignited. Due to the polymeric properties of p-aramid, the present net is slightly susceptible to UV light. For the present application being used inside tunnels, the chance of the net deteriorated by UV light is greatly reduced.
- PA6, PA66, or the like polyamide
- UHMWPE ultra-high molecular weight polyethylene
- the bearing capacity of the present protective net is at least 0.3 Ton, or at least 0.5 Ton, or at least 1.0 Ton.
- the present protective net meets the UL94, V-0 rating and has an electrical resistivity of 10 9 ⁇ or more.
- an appropriate coating material may be applied to the present protective net for abrasion-protective and UV-protective purposes as long as the bearing capacity of the net is maintained.
- Suitable coating composition comprises at least 10-50% of a polyurethane (PU) resin, a carrier, and optionally, an ultraviolet light absorber, an extender, a plasticizer and/or dye.
- PU polyurethane
- Polyurethane resins typically are derived from reacting isocy ante-containing components and hydroxyl-containing components. Depending on the hydroxyl-containing components, polyurethane resins can be divided into acrylic polyurethane, alkyd polyurethane, polyester polyurethane, polyether polyurethane, epoxy polyurethane, etc.
- the polyurethane resin is preferably a polyester polyurethane and more preferably, a polyester aliphatic polyurethane.
- the carrier can be trichl or ethane, methylene chloride, perchlorethylene, water, xylene, xylol, toluene, mineral spirits such as naphtha, or a mixture thereof.
- the carrier is water.
- the coating composition may also optionally include an ultraviolet (UV) light absorber to help extend the life of the coated protective net by preventing fiber breakdown due to exposure to sunlight.
- UV light absorbers such as benzotriazoles and benzophenones are available and compatible with the polyurethane resin of the coating composition.
- the presently preferred UV light absorbers are benzotriazoles, for example, TUNUVIN ® , available from BASF AG, Germany.
- the coating composition may optionally include an extender.
- a suitable extender is inert, durable, miscible, and abrasion resistant which is compatible with the polyurethane resin utilized.
- the extender can also be a filler having those same properties. Examples of suitable extenders include silicates, glass spheres, carbon black, or any of the various proprietary extenders.
- the presently preferred extender is carbon black, which is sold under the brand name CORAX ® (Degussa AG, Germany).
- the coating composition may also optionally include a plasticizer to increase the flexibility and durability of the coated net.
- Suitable plasticizers include esters of phthalate, benzoate, adipate and sebacate; polyols such as ethylene glycol and its derivatives; and castor oil.
- Preferred plasticizers include butyl octyl phthalate, di(z-ethylhexyl) phthalate, dibutyl phthalate, discotyl phthalate, diisodecyl phthalate, diisononyl phthalate, dipropylene glycol dibenzoate, and diethylene glycol dibenzoate.
- the presently preferred extender is benzoate esters, which is commercially avaible under the name BENZOFLEX ® from Eastman Chemical Company, USA.
- the coating composition is an aqueous polyurethane dispersion.
- the aqueous polyurethane dispersion comprises at least 10-50% of a polyurethane resin, wherein the polyurethane resin is a polyester aliphatic polyurethane.
- Suitable PU coating compositions are commercially available, for example, aqueous polyurethane dispersions from I-Coats N.V. (Belgium) under the tradename of ICO-THA E.
- the method for preparing a coated protective net comprises: i) providing a coating composition ofsufficient concentration, ii) applying the coating composition to the protective net for sufficient time to allow the coating composition to penetrate within the protective net fibers, iii) optionally, removing excess coating composition, and iv) drying the wet net.
- the coating composition may be applied to the protective net of the present invention by dipping, immersing, brushing, rolling or spraying. According to the application method, one skilled artisan can adjust the concentration of the coating composition by known methods, for example, diluting with an appropriate carrier.
- the wet net may be dried by suspending it or draping it over a drying rack at ambient temperature, and/or heating in an oven of 50-80°C for 60-400 minutes.
- the removal of excess coating composition may be accomplished by shaking the wet net, running the wet net through two, opposed rollers, by running the wet net over a series of spaced rollers, or by a number of other methods known to those skilled in the art.
- the content of the polyurethane coating material in the coated protective net is preferably about 5-15 weight% on the basis of the total weight of the coated protective net.
- the protective net of the present invention further comprises a polyurethane coating material.
- the content of the polyurethane coating material in the protective net is about 5-15 weight% on the basis of the total weight of the coated protective net.
- Base yarn p-aramid K29AP fiber, 1670 dtex, 1000 filaments/yarn, breaking strength of
- Net rope (a) twisted 4-6 p-aramid base yarns on a braider machine (S or Z twist, 60 tpm) to obtain a p-aramid strand; (b) braided 12 p-aramid strands to obtain a net rope having an equivalent diameter of about 3-5 mm.
- Frame rope (a) twisted 8-12 p-aramid base yarns on a braider machine (S or Z twist, 60 tpm) to obtain a p-aramid strand; (b) braided 12 p-aramid strands to obtain a frame rope having an equivalent diameter of about 8-10 mm.
- Tie rope (a) plied 3-4 p-aramid base yarns on a braider machine to obtain a p-aramid strand; (b) braided 6 p-aramid strands to obtain a tie rope having an equivalent diameter of about 1-1.5 mm.
- 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. .
- ICO-THANE 10 an aqueous polyester aliphatic polyurethane dispersion
- Abrasion Resistance Test The breaking strength was measured (So) and recorded for each and every samples including 6 coated yarns (CY1-CY6) and 6 uncoated yarns (Y1-Y6). The coated yarns were obtained according to the method as described in the coating test.
- Each yarn (55 cm long) was subjected to the abrasion treatment using a yarn abrasion tester (model SM-II, manufactured by Beijing Science and Technology Development Co., Ltd.).
- the ends of the yarn were fixed on 2 holders by crossing itself with a load of 2.5 Kg.
- the yarn holders moved back and forth at a frequency of 1 second per cycle, the yarn specimen was rubbing against itself. After the 600 cycles, the specimen was taken off the abrasion tester and the breaking strength of each specimen was measured (Si) and recorded.
- AS Loss of Breaking Strength
- the abrasion resistance of the yarns is judged according to the extent of the breaking strength loss.
- the data of Table 4 show that the PU-coated yarns have less loss of the breaking strength, thus higher abrasion resistance as compared to that of the uncoated yarns.
- Load Force Test 5 specimens of net ropes (40 cm in length and 5 mm in equivalent diameter) were tested for load force on an Instron 9995 universal test machine. The load force of the net rope was measured according the ASTM D7269 method. The data are listed in the table below and the average load force of the tested net rope having an equivalent diameter of 5 mm was 16641 N.
- the net was weighed (Wo) and immersed in a container containing about 50 L of the PU coating composition for 10 minutes at room temperature. After removal from the container, the net was dried at ambient temperature overnight to allow the PU coating material cured and weighed again (Wi).
- the content of the polyurethane coating material of the coated net was calculated by the equation shown below:
- the net specimen was hooked on the frame of a burst tester, which was a 1000 KN burst test equipment (manufactured by Sichuan Aote Machinery Co., Ltd., Chengdu, China).
- the load force of the net was determined by the maximum force to cause no more than 5 bursting meshes.
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Braiding, Manufacturing Of Bobbin-Net Or Lace, And Manufacturing Of Nets By Knotting (AREA)
- Lining And Supports For Tunnels (AREA)
- Ropes Or Cables (AREA)
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CN111561329B (zh) * | 2020-05-11 | 2022-03-15 | 中铁十八局集团有限公司 | 一种铁路隧道仰拱下方水库爆顶透水窟窿修补方法 |
CN112459808B (zh) * | 2020-12-21 | 2023-08-11 | 中铁第一勘察设计院集团有限公司 | 防护棚架 |
CN115341558B (zh) * | 2022-08-17 | 2023-06-02 | 招商局重庆交通科研设计院有限公司 | 一种岩质边坡生态防护系统 |
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WO2008087537A2 (en) * | 2007-01-18 | 2008-07-24 | Skarboevig Nils Mittet | A support net for underground mine supports |
US20100327244A1 (en) * | 2008-02-06 | 2010-12-30 | Yoichi Nishita | Shock-absorbing fence |
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JP2004027764A (ja) * | 2002-06-28 | 2004-01-29 | T-Net Japan Co Ltd | 構造面の補強工法 |
ZA200308890B (en) * | 2002-11-15 | 2005-02-23 | Nicaud Companies 22 (Pty) Ltd | Safety device |
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JP2010077569A (ja) * | 2008-09-29 | 2010-04-08 | Unitika Ltd | 糸用コーティング剤およびこれを塗布した糸 |
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WO2008087537A2 (en) * | 2007-01-18 | 2008-07-24 | Skarboevig Nils Mittet | A support net for underground mine supports |
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CN108723261B (zh) * | 2018-07-10 | 2023-08-18 | 山东交通学院 | 双交叉扭丝网片联接机 |
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CN115162221A (zh) | 2022-10-11 |
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