EP0087125B1 - Method of proofing geological seams, as well as weather and fire dams - Google Patents

Description

The invention relates to a method according to the preamble of the main claim.

It is known that exposure to water, e.g. in the form of moist air, which greatly reduces the strength of clay-bearing minerals, which can lead to complete decay. With swellable rocks, the processes may run very quickly. Especially in mining and tunnel construction, the water content of such rocks increases rapidly from the surface due to the high humidity in the weather, and thus the strength of the rock decreases.

This manifests itself among other things in the stripping of layers of rock, in rockfalls, in the swelling of the sole and in general in a stronger convergence of the mountains, while increasing rock movement and pressure.

In the case of chamber arrow construction in hard coal mining, this can mean that approx. 30 cm of top coal must be grown in the hanging area to prevent the route from collapsing. By applying a water-impermeable cover layer, the swellable rock can be preserved, thus allowing the seam to be completely broken down.

In underground operations, routes often have to be sealed against creeping weather currents. These lead to smoldering fires, especially in dumped mines. In order to prevent this, fire protection dams are built to protect the potential fire zone from further oxygen access. Weather dams are built to ensure the exact and effective weather management that is necessary for the people working on site.

For this purpose, weather or fire protection dams made of wood or mineral material are usually erected, which, however, have gross leaks, especially in the transition areas dam - butt and dam - roof. The weather losses are increased by loosening and thus permeability of the surrounding mountains. The leaks on the dam itself are usually sealed by applying mortar or urea-formaldehyde foams. With mountain movements, however, cracks can easily occur in the coating, especially when using mortar, so that the dam is no longer tight. In a similar way, when building pillars, great weather losses occur due to the fact that the coal pile of the construction site to be ventilated is permeable to the neighboring building.

DE-B-1082867 describes a method for sealing weather or fire dams by simultaneously spraying on a latex dispersion and a precipitant, as a result of which an air- and liquid-tight film is applied. However, the flame resistance of this film is unsatisfactory.

By using the method according to the invention, the disadvantages described can be avoided by simultaneously spraying the latex dispersions onto the area to be covered by means of compressed air via separate pipelines using a dry hydraulic binder.

With the help of hydraulic binders, especially cements, a double effect is achieved. The cement acts both as a coagulant for the dispersion and, moreover, as a means of solidifying the respective covering.

For the application of the method according to the invention, a gate crusher is preferably used, in which the hydraulic binder is conveyed with compressed air and the aqueous rubber or plastic dispersion is added through nozzles at the outlet end of the delivery pipe instead of water, so that a mixture of binder is obtained from the delivery pipe and dispersion is sprayed.

The rubber content can be varied within wide limits. Fractions of up to 50% by weight, based on cement or other hydraulic binders, are readily possible; 5 to 20% by weight solids content of the dispersion are preferred. If the rubber content is low, it may be necessary to add water to the dispersion so that the amount of water required for the hydraulic setting process is available.

In principle, devices can be used as they are designed for the normal gate cleaning process. However, it has proven to be advantageous to design the holes in the nozzle through which the water and in this case the latex is normally fed so that the latex uniformly wets the flow of the binder over the entire cross section. For this purpose, the originally radial bores of the nozzle are changed in a tangential direction. This measure results in a uniform moistening of the mixture of the binder with latex and the inevitable rebound of the binder from the sprayed surface is reduced to a minimum.

The type of dispersion to be used depends on the type of cement used. Experience has shown that in the case of Portland or blast furnace cement, preference is given to using cationic or amphoteric latices as binders or appropriately composed quick binders, while anionic or anionic / nonionic latices are predominantly used when using alumina cement or appropriately composed quick binders.

Although many latices and plastic dispersions are suitable for the process, due to the particularly high flame-retardant requirements for use in hard coal mining, only latices are suitable that have a high halogen content, preferably latices based on poly-2-chlorobutadiene or copolymers 2-chlorobutadiene and dichlorobutadiene. If there is no fire risk, e.g. the following dispersions into consideration:

The injection of the latices into the jet consisting of dry binder is, as was not to be expected, trouble-free, even if the nozzles through which the latices are pressed have a diameter of only 0.5 to 2 mm. It was to be feared that due to the shear forces occurring during the atomization, the latices would coagulate and thus clog the nozzle. The sprayed mixture of latex and binding agent tends to flow away from the sprayed surface, depending on the inclination of the surface. According to the invention, this tendency can be successfully countered by using binders, in particular cements, with particularly short setting times, namely from 10 to 150 min, preferably 30 to 90 min - measured according to DIN 1164.

Early addition of the sprayed-on mixture can also be successfully countered by adding inert fillers to the binder. All non-quartz-containing fillers are preferred as fillers, since rebounding of the atomized mixture is difficult to avoid and the inhalation of the resulting rebounding, quartz-containing mist would be harmful to the health of the user. According to the invention, for example, coarse-grained to fine powdered refractory materials, of which up to 8 times the amount of the binder can be added to it.

In order to maintain the stability of the dispersion even beyond the atomization process, the addition of surfactants in small amounts to the latices is recommended, e.g. B. to cationic or amphoteric latices surfactants in amounts up to 0.2 to 1% and to anionic or anionic / non-anionic latices surfactants with corresponding properties.

In any case, the dispersions should be readily flowable and their solids content should be 30 to a maximum of 70% by weight.

example 1

In a test tunnel with a cross-section of 12 m ² , a rapid dam was built by spraying an elastic cover with the help of a goalie device with an average thickness of 20 mm against a wire mesh that was stretched over the entire cross-section. The hydraulic binder consisted of alumina cement with a setting time of 60 minutes. The plastic dispersion, consisting of a 58% polychloroprene dispersion (Baypren Latex B), was metered into the cement in a ratio of 9: 1 (binder: dispersion).

The original amount of weather of 850 m ³ / min immediately decreased behind the cover to 4 m ³ / min, whereby a pressure drop between the tunnel area in front of and behind the Schnelldamm of 520 Pa was established. Even if the pressure drop increased to 1.020 Pa or 2.450 Pa due to increased fan power, the amount of weather behind the cover did not rise above 5 m ³ / min or 11 m ³ / min.

Example 2

The top section of a thrown-out mine structure with a cross-section of 16 m ² was closed with a dam made of brick masonry. This reduced the amount of weather on the route from 1.650 m ³ / min to 4.5 m ³ / min. Subsequently, an average 50 mm thick layer of commercially available shotcrete was applied to the dam and to the edge of the stretch and ridges up to 4 m from the dam by means of a gate scraper, which reduced the amount of weather behind the dam to 0.8 m ³ / min. After a week, the amount of weather behind the dam rose 1.2 m ³ / min, after 4 weeks to 2.0 m ³ / min. The first cracks in the shotcrete became visible, after 6 weeks some pieces started to burst out of the dam. The amount of weather increased to 2.8 m ³ / min after 2 months.

Thereupon a new dam was set with a goalie device, with latex-containing shotcrete, consisting of amphoteric polychloroprene latex on the one hand and a mixture of granular to powdery fireclay and Portland cement with a setting time of 60 min in a ratio of 3: on the other hand, applied on average in a thickness of 25 mm. The amount of weather decreased to 0.5 m ³ / min and did not exceed 1.2 m ³ / min even after 2 months.

Claims (6)

1. Method of coating geological formations as well as weather- and fire barriers with the aid of aqueous rubber- and/or rubber-like dispersions, characterised in that these dispersions are sprayed via separate conduits simultaneously with a dry hydraulic binding medium, by means of air pressure, onto the place to be coated.

2. Method according to claim 1, characterised in that the hydraulic binding medium has a hardening time of 10 to 150 min., preferably 30 to 90 min. (according to DIN 1164).

3. Method according to claim 1 to 2, characterised in that inert filling materials, of a weight quantity up to not more than 8 times that of the hydraulic binding medium, are added to said hydraulic binding medium.

4. Method according to claim 1 to 3, characterised in that a tenside is added to the dispersions.

5. Method according to claim 1 to 4, characterised in that the dispersions have a content of solid matter amounting to 30 to 70%.

6. Method according to claim 1 to 5, characterised in that the content of solid matter of the dispersion amounts to 5 to 20 weight percentage of the binding medium proportion.