Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
  • E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
  • E21F17/16—Modification of mine passages or chambers for storage purposes, especially for liquids or gases

Definitions

• the present invention relates to materials and their use in processes for the production of closure structures for closing cavities, which occur especially in underground construction in so-called manhole structures, but also as a dam construction in the line closure.
• Hazardous waste such as Highly toxic or radioactive substances are deposited in mines and disposed of to permanently isolate them from the environment. This happens in barrels, drums or other containers, which are spent in underground caverns (cavities). When the usable space of the cavern has been exhausted, the free space between the various containers is filled with solid material to ensure sufficient compressive strength of the storage pile while avoiding possible collapsing of the ceiling. Subsequently, these cavities must be permanently sealed watertight to guarantee safe long-term storage of the substances mentioned.
• the sealing against water ingress in such closure structures is produced by so-called sealing plugs made of bentonite.
• the building material is spent underground and also compacted underground to achieve the required low water permeability.
• Another possibility is the use of bentonite shaped bricks, which are made overground and built underground as dry masonry.
• the cohesive material preferably bentonite or bentonite stones.
• the cohesive material in particular bentonite, swells when absorbed by water and considerably increases its volume. Due to the increase in volume there is a pressure build-up. This effect is used to create a permanently watertight sealing plug for the cavity to be closed with the aid of cohesive (and at the same time swellable) material. For this, however, it is again necessary to compact the bentonite beds underground as evenly as possible with hydraulic devices.
• At least one layer of a further material is disposed within the backfilling of the cohesive material.
• This further layer is at an angle of 60 ° to 90 ° to the water inlet direction, is between 2 and 30 cm thick and has a water permeability that is at least ten times greater than that of the bentonite or the cohesive material.
• the invention was thus based on the object of finding a method and / or suitable materials and building materials with which or with which closure structures or sealing plugs, in particular for closing cavities, can be produced in the most efficient manner possible. It was important to note that these cavities can be located underground in particular and a closure should normally be watertight. Further work should be underground during the creation of such closure structures are at least largely avoided.
• a material combination or composition according to the invention which serves as a closure material and basically consists of highly compressed moldings, preferably pellets, of a cohesive material and an inert gusset filling.
• the closure construction or the sealing plug consists of this closure material. Additional abutments or dry masonry are usually required for structural reasons, are required as a building and are not considered here.
• the term closure construction used according to the invention therefore comprises only the actual closure stopper and not the abutments required for static reasons, which are preferably designed as concrete abutments.
• the closure material can be installed as a finished mixture of moldings / pellets and inert gusset filling at the installation site, this is the variant preferred according to the invention.
• the components are also possible to install the components as separate beds (pellets as bed 1 and gusset filling as bed 2) alternately or successively.
• the introduction takes place by the loose plunging of the closure material as a mixture or as separate beds 1 and 2 (for example as a loose crevice into a manhole structure) or, preferably, in the blowing offset, in which again preferably a prefabricated mixture of the components of the closure material is used.
• the requirements for the closure material depend on the requirements of the closure structure produced therefrom (swelling volume, swelling pressure, tightness to pending media / test liquids), which in turn depend on the local conditions, in particular the expected upcoming water column and the resulting hydrostatic pressure , And whether the closure must be largely or completely as possible sealing against possible ingress of water or only a temporary structure, for example in the line closure represents.
• the closure structure will have to be largely water-tight.
• the resulting requirements on the closure structure and thus on the closure material used are then preferably determined by the following parameters: installation density of the closure material without additional local compaction of greater than 1.7 t / m 3 (kg / dm 3 ), in particular between 1.7 and 2.1 t / m 3 .
• Installation density of the closure material without additional local compaction of greater than 1.7 t / m 3 (kg / dm 3 ), in particular between 1.7 and 2.1 t / m 3 .
• Swelling pressure builds up when a volume increase (swelling) caused by water absorption is hindered (eg by a surcharge).
• the sealing plug or the closure material should moreover have water permeabilities (characterized by the permeability coefficient k f in m / s) of k f less than 10 -11 m / s, in particular less than 10 -12 m / s (determination of water permeability according to DIN 18130).
• the moldings or pellets to be used according to the invention as a component of the closure material are preferably cylindrical, highly compressed moldings which are produced by vacuum extrusion.
• Their bulk density is preferably more than 2.0 t / m 3 corresponding to a dry bulk density of about 1.8 to 2.0 t / m 3 .
• the preferred dimensions are at a diameter of up to 20 mm, preferably 6 - 10 mm, and a length of about 5-30 mm, preferably also 6-10 mm, about a cylindrical, but also isometric as possible mold body respects length / To achieve latitude. Even with this material, a volume filling of about 60-65% by volume, corresponding to a void volume of about 35-40% by volume, would result in a single-grain bed (bed 1).
• the shaped bodies of cohesive material preferably contain minerals of the smectite group. These are minerals and mineral mixtures of various swellable phyllosilicates, which have a three-layer structure and belong to the clay minerals.
• the pellets contain these minerals to at least 60 wt .-%, preferably to more than 75 wt .-%.
• the most important representative of these smectite minerals is the layered silicate montmorillonite, which is preferred to the above contained in the pellets.
• these pellets or molded articles consist of pure bentonite.
• Bentonite is a natural, plastic clay rock which, in addition to quartz, mica, feldspar, pyrite or even calcite, contains montmorillonite as the most important constituent to about 60-80 wt .-% in addition to other clay minerals.
• An essential point to be considered in the production of the shaped bodies according to the invention is a certain residual water content, so that the shaped bodies have the mechanical properties required for the purpose according to the invention.
• the pellets too dry, there is an increased risk of breakage in the fall, which can hinder the penetration of Inertkorns in the gusset massively.
• the pellets may burst because the absorption of water can lead to immediate and possibly uncontrolled swelling with the build-up of a corresponding swelling pressure. Therefore, depending on the material used, residual water contents of preferably less than 20 wt .-%, in particular less than 18 wt .-%, to strive for.
• the residual water content should preferably not fall below 10% by weight and in particular 8% by weight, since this is in addition to the above-mentioned. adverse properties may lead to too dry material.
• the second component of the closure material according to the invention is a so-called inert gusset filling for filling the gussets, which, as stated above, would form in a single-grain bed of the shaped bodies according to the invention. Under gusset one understands the cavity between the particles of a heap.
• the inert gusset filling is a highly flowable inert material. This inert material is preferably of a rolling grain, so that it can penetrate particularly well into the cavities or gussets formed by the shaped bodies or pellets and can completely fill them.
• inert materials having a maximum particle size of up to 1 mm, in particular having a maximum particle size of less than 0.25 mm.
• the largest grain of a corolla (Dmax) is the denomination of the largest grain of the coarsest grain group.
• Highly advantageous inert materials of rolling granulation with a narrow grain gradation between 0.25 mm and 0.1 mm are very advantageous.
• Such materials are commercially available, eg quartz sand plant Haltern H 35 S the company Quarzwerke GmbH, Frechen. This consists of more than 99 wt .-% of SiO 2 , has an average grain size of 0.17 mm with 98 wt .-% of the grains in the range of 0.09 to 0.25 mm.
• coarser inert materials (larger largest grain size, wider grain grading) can also be used.
• the inert gusset material thus preferably consists of fine sand, in particular quartz sand.
• the following substance classes are suitable with appropriate grain size and distribution as Zwickelfüllung invention: inert metal oxides and silicates, such as oxides of spinel or Felds Georgte, but also all other inorganic minerals, which pose no threat due to their water insolubility in terms of long-term safety of the building , Increased water solubility as an exclusion criterion would for example be the case with most carbonates or sulfates with the exception of barite.
• the selection of suitable materials depends on the requirements of the closure structure, which are significantly dependent on the conditions of the construction site.
• the gusset filling (bed 2) in addition to the inert fine material, e.g. in the form of sand, also containing correspondingly fine-grained cohesive material according to bed 1 (for example smectite-group minerals or pure bentonite-fine granules).
• bed 1 for example smectite-group minerals or pure bentonite-fine granules
• the method according to the invention for producing a closure construction particularly preferably includes the installation of the closure material in the form of a prefabricated mixture by blowing this mixture (blown offset), e.g. from a silo truck with built-in or separate blowing device.
• composition of this mixture of bed 1 (moldings / pellets) and bed 2 (inert gusset filling, eg sand) is preferably dimensioned so that, starting from the theoretical cavity filling or between the pellets forming cavity, the proportion of moldings always something is. This has the consequence that after completed installation of the mixture inert gusset filling can be poured to fill up last remaining gusset. In doing so, we suppress the formation of lenses made of gusset material (eg, sand lenses) that form a higher water permeability could result.
• the advantages of the method according to the invention are, in particular, that one can install the closure structures in an extremely short construction period, no (or significantly reduced) man-days on site (underground) are necessary because the closure material is spent immediately to the site, especially by the Method of blowing offset.
• inventive method closure structures coupealing layer thicknesses or plugs in any thickness, eg with layer thicknesses of 5 m) produced without interrupting construction or working underground. A compaction of the closure material on site can be omitted.
• closure materials according to the invention can be arbitrarily dimensioned sealing structures with, depending on the material used, the desired water permeabilities k f generate. Even with a simple camber offset, installation densities of greater than 1.7 t / m 3 can be achieved, which can be increased to values of up to and greater than 1.9 t / m 3 due to the advantageous blowing offset.
• Fields of application are generally the closing of cavities underground, as is necessary, for example, in the (final) storage of toxic and radioactive materials, the screening of parts of a mining district against inflowing surface water and / or pressurized groundwater; ie generally the creation of hydraulic barriers.
• the method and the associated material concept are not only shaft closures but also for the construction of dam structures in lines suitable.
• the advantage of Blasversatzes results under the ridges. In conventional construction methods, compaction under the roof is not possible.
• the invention thus encompasses the use of the described materials, separately or as a prefabricated mixture, for the production of closure structures, a process for the production of closure structures using the materials according to the invention and closure structures, which can be produced with the materials mentioned and according to the described process.
• a mixture of 30% by weight of the described quartz sand H 35 S and 70% by weight of highly compressed pellets consisting of pure bentonite is produced.
• the sand has a density (grain density) according to DIN EN ISO 787-10 of 2.65 g / cm 3 (t / m 3 ).
• the pellets have the following dimensions: diameter 10 mm, production-dependent between 5 and 15 mm, a grain density (dry bulk density) of 2.1 g / cm 3 , a swelling volume of 400 ml (upper edge of the swollen pellets in a 500 ml wide-mouth beaker at 100 g of pellets) and an Enslin-Neff water absorption of 370%.
• This mixture is filled into a silo truck and blown the material about 350 meters out of the silo train via a blow pipe in an underground test. It is about 300 m vertically and about 30 m horizontally above ground and about 20 m horizontally underground. In the experiment, a bucket is buried directly in a track end and exposed to the flow.
• the table also shows the already described partial grain destruction of the pellets in a comparison of the particle size distribution of the starting mixture and the blown material.
• fine-grained cohesive material here bentonite
• the binary mixture according to the invention in accordance with exemplary embodiment 1 is installed in multiple layers by means of blast displacement in alternating storage with sand layers.
• 786.94 t of material are installed here for a total volume of 456.54 m 3 .
• the density achieved is thus 1.72 t / m 3 due to loose cinder without subsequent compaction on site.

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• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Geology (AREA)
• Sealing Material Composition (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Bulkheads Adapted To Foundation Construction (AREA)

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• 2013
  • 2013-09-02 DE DE102013109521.6A patent/DE102013109521A1/de not_active Withdrawn
• 2014
  • 2014-08-20 PL PL14181512T patent/PL2843190T3/pl unknown
  • 2014-08-20 EP EP14181512.6A patent/EP2843190B1/fr active Active

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