FI72207C - Protective mat and procedure for covering explosive objects. - Google Patents

Abstract

1. A protective mat for covering articles which are to be explosively blasted, characterized in that it consists of a nonwoven textile sheet-like structure of synthetic continuous filaments or staple fibres, which on determination of the tension-elongation behaviour according to DIN 53857 has a tensile strength of 30-100 n/5 cm at 10 % elongation, a tensile strength of 100-400 N/5 cm at 30 % elongation, a tensile strength of 300-800 N/5 cm at 50 % elongation, a tensile strength of 500-950 N/5 cm at 70 % elongation and a tensile strength of 600-1100 N/5 cm at 90 % elongation, and a weight per unit area of at most 800 g/m**2, or that it consists of a plurality of such nonwoven textile sheet-like structures joined side by bonding, such as welding or stitching.

Description

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'^ - -> -' i - u 7 (51) Kv.lk. * / lnt.CI. * F ** 2 D 5/00 (21) Patent application - Patentansökning 792801 (22) Application date - Ansökningsdag 10.09.79 ( FI) (23) Starting date - Giltighetsdag 10.09.79 (41) Made public - Blivit offentlig 1 ^ .0 ^ .80

National Board of Patents and Registration Date of publication and publication. _ 31.12 86

Patent and registration authorities Ansökan utlagd och utl.skriften publicerad (86) Kv. application - Int. ansökan (32) (33) (31) Privilege claimed - Begärd priority 13.10.78

Germany 1i i ttotasavaita-Förbundsrepub 1iken Tyskland (DE) P 28 ^ 731.6 Proven-Styrkt (71) Chemie Linz Aktiengesel1schaft, St.-Peter-Strasse 25, Linz, I täva1ta-österr ike (AT) (72) Hermann Kressl, Weis , Austria-Österrike (AT) (7 ^) Lei tzinger Oy (5 * 0 Protective mat and method for covering explosive articles -Skyddmatta och förfarande för täckning av sprängbara föremäl The invention relates to a protective mat or mats for covering explosive articles. weaving from a textile coating consisting of man-made fibers overlappingly joined by a plurality of webs by welding or knitting overlapping to such a large size or by overlapping so that the object to be blown covered at least 1.5 m on both sides.

In order to carry out blasting operations of a civilian nature, which often have to be carried out in residential and industrial areas in the vicinity of objects which cannot in any case be damaged or endangered by explosive waves and possible detonation, explosives must be blasted, or other pressure-reducing, inherently relatively rigid materials, such as old car tires, etc. in a given area relative to the hazardous environment so that the explosive waves 2 72207 can be distributed around them and their front direction can be attenuated by a cover.

However, such cover or protective devices are expensive in terms of transport costs and storage space and are cumbersome to install.

It has now surprisingly been found that explosion sites can be covered simply and securely if they are covered with a mat made of endless wire or layer mats made of thermoplastic plastic fiber and laid apart, which meets the set requirements in terms of strength elongation ratios. This loose blanket, which must cross the blasting site to a certain extent, rises somewhat under the influence of the blast wave and traps the fragments flying around without tearing. It can even be used surprisingly with good success several times in a row.

The invention therefore relates to a protective mat for covering explosive articles, characterized in that it consists of one or more non-woven textile surfaces joined together, for example by welding or knitting, which is a synthetic endless yarn or ply fiber, the tensile strength of which according to DIN 53857 % elongation is 30 to 100 N / 5 cm, 30% elongation 100 to 400 N / 5 cm, 50% elongation 300 to 800 N / 5 cm, 70% elongation 500 to 950 N / 5 cm and with an elongation of 90% of 600 to 1100 N / 5 cm and a weight not exceeding 800 g / cm 2.

The carpet used as a protective mat can be assembled both by knitting and thermally. As the thermoplastic material from which the protective mat according to the invention is made, polypropylene, a crystalline copolymer of propylene and ethylene and polyester can be used.

Another object of the present invention is a method for covering objects to be detonated using one or more protective mats according to the invention. The method is characterized in that the object to be detonated is loosely covered with a protective mat or several overlapping protective mats so that the protective mat or mats extend at least 1.5 m on each side over the detonation field.

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If the blasting mat has to perform its function very confidently and also again, a stress on the middle stretch area of 10 to 80% is appropriate to ensure that irregular pressure shocks or fragments caused by the often unforeseen inhomogeneity of the material of the blasting object can still be captured. If a larger carpet surface is required to cover the blasting site more securely than the normal carpet width allows, two or more carpets can be joined at the edges by overlapping welding or knitting, but a 1.5-2 meter wide overlap is enough to capture the explosion pressure waves. Furthermore, it may be expedient when folding the carpets to fold the edges of the carpet in each case about 0.5 m into its lower surface. When moving, it must also be noted that the carpet remains movable everywhere. Tying or loading would cause it to be damaged or punctured. It is preferred that the explosive ignition wires, detonator capsules, electric bridge igniters and explosive delay placed on the surface of the blasting field (under the carpet) are covered with sand against the carpet or the carpet is preferably arranged a short distance from the detonator of the explosive.

The risk of static charging of the blasting mat, which could lead to premature and uncontrolled ignition of the ignition wire, etc., is avoided by treating the mat antistatic before use.

The subject of the present invention will be explained in more detail in the light of the following examples.

The technical data of the carpet used are as follows: Endless polypropylene fiber mat, knitted.

Carpet thickness: 3.5 m 2

Weight: 350 g / m

Tear depth, -20 ° C frozen: 40%

Tensile strength ratio according to DIN 53857: 100 N / 5 cm 10%, 400 N / 5 cm 30%, 600 N / 5 cm 50%, 700 N / 5 cm 70% and 900 N / 5 cm at 90% elongation.

Breakthrough resistance: No breakdown when dropped with a 30 kg drop hammer from a height of 2 m.

This mat was obtained by a conventional method of making a mat made of endless fibers by weaving, stretching in air and placing on a sieve.

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Example 1:

Blasting of four concrete foundations (foundations of former mineral oil tanks) in an urban area in the immediate vicinity of an electric railway.

Dimensions of the blasting site: Length 2.40 m, width 0.48 m, height 0.90 - 3 1.40 m, mass approx. 1 m per foundation, reinforced with 10 0 14 mm brush steel in the longitudinal direction and brush steel hook for transverse reinforcement.

Boreholes: 5 pieces, 0 36 mm, depth 70 - 80 mm.

Loading: 90 g gelatin donarite 1, caliber 30 mm / borehole. Stuttering: Full front loading.

Ignition: Electric, intervals 1-5 from south to north Protected sites: West: embankment, north: street and buildings, east: industrial buildings, firewall, south: parking lot and buildings. Covering the blasting area: Two carpets made of polypropylene endless fibers, each measuring 5 x 10 m. The carpets were installed by two men so that they each extended about 1.5 m outside the blasting field and overlapped each other by about 1 m. They were bent about 1 m from each corner. inward down.

Fragmentation effect: Minor due to blasting. A few small pieces of concrete were found at a distance of about 5 m from the blasting area.

Condition of carpets after explosion: Completely undamaged.

Example 2:

Blasting four other concrete foundations east of the blasting area. The conditions are as in Example 1.

Fragmentation: Minor, no damage.

Condition of the carpets as before attempt 1 or 2. Even after the two tests performed after this, the carpets were not said to be damaged.

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Example 3:

Surface icing for breaking stone for crushed stone production.

Dimensions: 4 0 36 mm borehole, depth 0,75 m, 2 0 36 mm borehole, depth 1 m. ' Stuttering length: 60 - 80 cm (full front loading).

Distance between holes: about 80 cm.

Charging: 4 x 130 q and 1 x 178 g gelatin donarite 1, caliber 30/200.

Ignition: Electric, quick start.

Ignition field coverage: 1 piece of knitted carpet made of polypropylene endless fiber 5 x 5 m, which means covering about 2 m over the explosion field.

Carpet condition after explosion: Flawless, no damage. Example 4:

Blasting of two concrete foundations under the conditions of Example 2. To separate from Example 2, a knitted polypropylene layer mat having the following characteristics has been used: 2

Surface weight: 400 g / m.

Tensile elongation ratios according to DIN 53857: 70 N / 5 cm 10%, 300 N / 5 cm 30%, 550 N / 5 cm 50%, 700 N / 5 cm 70% and 800 N / 5 cm with 90% elongation.

Under the same charging and ignition conditions, no significant splinter effect occurred and only minor damage was observed in the carpet.

Claims (5)

6 72207 Patents, patent applications 1. A protective mat for covering explosive articles, characterized in that it consists of one or more non-woven text ii 1 ip.strings joined together, for example by welding or knitting, which is a synthetic endless yarn or ply fiber, the tensile strength of which according to DIN 53857 shows that 10% elongation is 30 to 100 N / 5 cm, 30% elongation 100 to 400 N / 5 cm, 50% elongation 300 to 800 N / 5 cm, 70% elongation 500 to 950 N / 5 cm 5 cm and with 90% elongation 600 to 1100 N / 5 cm and weighing not more than 800 g / cm 2. Protective mat according to Claim 1, characterized in that the fibers are thermally bonded. Protective mat according to Claim 1, characterized in that the fibers are fastened by needling. Protective mat according to Claims 1 to 4, characterized in that the mat fiber is a polypropylene or polyester fiber. A method of covering explosive articles to prevent the material to be detonated from being ejected using a protective mat according to one or more of claims 1 to 4, characterized in that the object to be exploded is loosely covered with a protective mat or several overlapping protective mats so that the protective mat or mats extend at least 1.5 m on each side. over the blasting field. Il