DK150958B - APPLICATION OF ANY OR MORE COMBINED TEXTILE INTERFACES AS PROTECTIVE PURPOSES - 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

in 150958

The present invention relates to the use of one or more non-woven nonwoven textile surface elements of staple fibers or endless strands of thermoplastic resins, preferably 5 endless strands of polypropylene or polyester, as protective mats for shielding blasting objects.

Civilian blasting works often have to be carried out in residential and industrial areas near objects that must not be damaged or exposed to explosions. In order to intercept the detonation wave and possibly thrown fragments of the blasted object, hitherto shielding of the blasting object has been used, and in particular those prone parts thereof, with straw bales or other pressure attenuating and in themselves rather rigid materials, applied at a certain distance from the exposed environment, so that the detonation wave can spread over the intermediate airspace and be trapped in frontal direction 20 by shielded materials. However, it is quite cumbersome to store and transport such shielding or protective materials, and their setup requires considerable work effort.

25 Surprisingly, it has now been found that blasting objects or sites can be shielded in a simple and secure manner when covered loosely with one of endless synthetic threads or thermoplastic staple fibers that meet certain tensile strength-to-30 requirements. the team. Such a loose shielding mat, which extends beyond the blast site, to some extent will be lifted by the detonation wave, allowing it to intercept the flying blast pieces without even being torn apart. Surprisingly, such a mat can be successfully used for repeated blasting.

The invention thus relates to the use of one or more non-woven nonwoven textile surface elements of staple fibers or endless strands of thermoplastic resins, preferably polypropylene or polyester endless strands, which surface elements in determining tensile strength ratio 10 according to DIN 53857 at an extension of 10% exhibit a tear strength of 30-100 N / 5 cm, at an extension of 30% exhibit a tear strength of 100-400 N / 5 cm, 15 at an extension of 50% exhibit a tear strength of 300-800 N / 5 cm, at an extension of 70S exhibits a tear strength of 500-950 N / 5 cm and at an extension of 90% exhibits a tear strength of 600-1100 N / 5 cm, which also has a surface weight of not more than 800 g / m2, as the protective mat for shielding blasting objects, the blasting object being covered with one or more overlapping protective mats in such a way that the protective mat (s) on all sides reach min. dst 1.5 m beyond the blasting field.

The mat used in the invention may be needle-reinforced or reinforced by thermal bonding. As a thermoplastic material for the production of the protective mat, polypropylene, crystalline copolymers of propylene and ethylene as well as polyester can be used.

3 150958

A shielding of blasting objects using one or more mats according to the invention is accomplished by the blasting object being loosely covered with one or more mats in such a way that the blasting site 5 and the surrounding area are covered by the mat or mats to a distance of at least 1.5 m from the center of the blasting site.

In order for a blasting mat used in accordance with the invention 10 to perform its function safely, even in repeated use, a load corresponding to a stretch of 10-80¾ is appropriate. In this way, it is possible to safely detect irregular thrust or fracture impact caused by often unpredictable irregularities in the structure of the blasting objects.

If a larger mat surface is required for safe shielding of the blasting object than the normal width of the textile web used permits, two or more 20 textile webs may be bonded together by overlapping welding or sewing. Optionally, a 1.5-2 m wide overlapping loose coating may be sufficient to intercept the detonation wave. Furthermore, when positioning the mats it may be convenient to fold 25 up to approx. 0.5 m of the material inserts on the underside, taking care that the mats can be moved between them. Tying or loading the mat would only cause it to be damaged or pierced, respectively. The detonating spark plugs, explosion caps, electric lighters and detonation retarders located on the surface of the blasting field (below the 30 mat) can be advantageously shielded with sand against the mat or the mat can be placed at a suitable distance from the explosive elements concerned.

The danger of a static charge of the blasting mat which may cause premature and uncontrolled ignition of detonating spark plugs or other ignition elements may be avoided by antistatic treatment of the mat prior to use.

The use of the blasting mat according to the invention 10 is explained in more detail in the following examples.

The material used has the following technical data:

Stitched webs of endless polypropylene fibers.

Material thickness: 3.5 mm.

Weight: 350 g / m2.

Tear strength, in the frozen state at -20 ° C: 40%. Tensile breaking strength ratio according to DIN 53857: 100 N / 5 cm at 10%, 400 N / 5 cm at 30%, 600 N / 5 cm at 50%, 700 20 N / 5 cm at 70% and 900 N / 5 cm at 90% elongation.

Breakthrough Strength: No impact on falling 30 kg of solder from 2 meters height.

This fiber material was obtained by a conventional method 25 for producing fiber webs of endless fibers by spinning, drawing through air and depositing on a suitable substrate.

EXAMPLE 1 30 Explosion of 4 pcs. concrete slabs (formerly used under a mineral oil tank) in the urban area in the immediate vicinity of an electrified railway line.

5 150958

Scope of blasting object: length: 2.40 m, width: 0.48 m, height: between 0.90 and 1.40 m, mass: approx. 1 m3 per shelf, 5 reinforcement: 10 pcs. reinforcing steel, 14 mm longitudinal diameter and transverse reinforcing steel bracket.

Boreholes: 5 pcs. diameter 36 mm, depth 70-80 cm.

Charge: 90 g gelatin donarite 1, caliber 30 mm / borehole.

10 Filling: complete filling.

Ignition: electric with time steps 1-5 from south to north.

Objects to be protected: west: railroad dam, north: street and buildings, 15 east: industrial building, refractory wall, south: parking lot and buildings.

Shielding screen: 2 stitched mats of endless polypropylene fibers, each with dimensions of 5 x 10 m.

20 The mats were placed by two men so that each of them projected approx. 1.5 m beyond the blasting field and overlapping each other by 1.5 m. The lower edges of the mats were folded inwards by approx. 1 m.

25

Scattering: negligible. A few small pieces of concrete were found in ca. 5 m distance from the blasting field.

The condition of the mats after the blast: completely unobtrusive.

EXAMPLE 2

Explosion of 4 more. concrete slabs east of the blasting field. The same assumptions as in Example 1.

5 Spread: negligible, no adverse effects.

The condition of the mats after blasting was the same as in the previous experiments. Also, on two more attempts, the mats were significantly damaged.

EXAMPLE 3

Surface cracking in a quarry in connection with shear production.

15 Scope: 4 boreholes 36 mm diameter, depth 0.75 m, and 1 borehole 36 mm diameter, depth 1.0 m.

Filling length: 60-80 (complete filling).

Distance between boreholes: approx. 80 cm.

Charge: 4 x 130 g and 1 x 178 g gelatin donarite 1, 20 caliber 30/200.

Ignition: electric torque ignition.

Screening of the blasting field:

One endless polypropylene fiber mat, 5 x 5 m, corresponding to a cover 25 of approx. 2 m beyond the blasting field.

Mat condition after blasting: impeccable, no damage.

EXAMPLE 4

Cracking of 2 concrete blocks under the conditions set out in Example 2. Unlike Example 2, a needle reinforced mat made of polypropylene staple fibers was used as a shielding mat.

Surface weight: 400 g / m2.

Tensile breaking strength ratio according to DIN 53857: 70 N / 5 cm at 10%, 300 N / 5 cm at 30%, 550 N / 5 cm at 50%, 700 N / 5 cm at 70% and 800 N / 5 cm at 90% extension.

10

Under the same filling and ignition conditions, no significant scattering effect and only negligible damage to the mat could be observed.

Claims (2)

150958 _ 8 Use of one or more non-woven nonwoven textile surface elements of staple fibers or endless yarns of thermoplastic moldings, preferably endless yarns of polypropylene or polyester, which surface elements in determination 10 of the tensile strength ratio according to DIN 53857 at a 10% extension exhibits a tear strength of 30-100 N per second. 5 cm, at an extension of 30¾ exhibits a tear strength of 100-400 N per second. 5 cm, at an extension of 50¾ exhibits a tear strength of 300-800 N per second. 5 cm, at an extension 15 of 70% exhibit a tear strength of 500-950 N per second. 5 cm and at an extension of 90% exhibit a tear strength of 600-1100 N per second. 5 cm, which further has a surface weight of not more than 800 g / m2, as a protective mat for shielding blasting objects, the blasting object 20 being covered with one or more overlapping protective mats in such a way that the protective mat or mats reach at least 1 , 5 m beyond the blasting field.