Geomaterial sheet with biodegradable properties

Description

[0001] The invention relates to a geomaterial sheet, a method for soil stabilization by means of a geomaterial sheet and a use of a geomaterial sheet for soil stabilization.

[0002] Geomaterial sheets, also known as geotextiles (or traditionally geosynthetics), are used in a variety of ways to stabilize soil layers. Typical examples of such diverse applications include slope reinforcement, dike construction, riverbank protection along rivers and lakes, stabilizing slopes in landfill areas, and stabilizing roadways and track construction. Geomaterial sheets are typically installed at a predetermined depth, meaning they are covered by soil layers, but can also be installed on the surface in individual cases.

[0003] The geomaterial sheet is designed to stabilize the soil layer and layer boundaries between soils, i.e., to prevent erosion or soil displacement and mixing, to prevent or reduce soil material displacement, such as through flow-induced erosion and redeposition of soil material, and to prevent the overall sliding of soil layers. Geomaterial sheets can be used as a permanent solution, particularly where natural processes such as root penetration or other soil consolidation mechanisms cannot stabilize the soil layer or layer boundaries.In many applications, geomaterial sheets are installed to achieve a temporary, temporary mechanical stabilization effect that stabilizes the soil layer to such an extent that plant growth is achieved. Additional long-term stabilization of the soil layer can be achieved through root penetration by these growing plants. A geomaterial sheet used as a reinforcement mat is known from EP 2 439 342 A1.

[0004] One problem associated with such geomaterial sheets is that the artificial substance introduced into the soil represents a potential environmental risk, whereby this environmental risk occurs at the installation site itself or, if mechanical influences or other effects cause the geomaterial sheet to be torn into smaller sections and moved away from the installation site, at other locations. To overcome these disadvantages, it has generally been proposed to manufacture geomaterial sheets from biodegradable materials. DE 295 16 797 U1, for example, discloses a covering layer made of a material, which can consist of natural fibers. US 2013 / 0344759 A1 discloses a geotextile with a non-woven structure in which plant fibers are used in its production. For this purpose, hemp fibers are proposed as a replacement for the previously known jute or coconut fibers.

[0005] A disadvantage of the proposed biodegradable geotextiles, however, is that in many applications the desired mechanical soil stabilization is not guaranteed over the required period. Biodegradation leads to the loss of mechanical protection, and undesirable soil movements such as landslides, dike damage, and the like can occur. Although a fiber coating is proposed to prevent these problems, this runs counter to the actual goal of achieving biodegradability and creates an environmental risk emanating from the coating. The use of biodegradable geotextiles made from the aforementioned previously known natural fibers therefore cannot produce satisfactory results in many applications or fails to meet the time requirements for mechanical stabilization.For geosynthetics, DIN EN 12225 therefore specifies test criteria to demonstrate general resistance to microbial degradation.

[0006] EP3385426A1 discloses a non-directional cellulose fiber material produced directly from a lyocell solution. This prior art describes the use of a non-directional cellulose fiber material for the production of geotextiles used as seed protection covers, capillary mats, for water purification, irrigation control, asphalt overlay, soil stabilization, drainage, or sedimentation and erosion control.

[0007] US2009 / 0317583A1 describes a sealing membrane made of moisture-absorbing fibers that swell upon absorption of moisture. Lyocell fibers are described as an example.

[0008] JP2007217973A describes a method for preventing the topsoil layer from running off by placing a water-absorbing and aerating layer on the soil.

[0009] JP2015200107A describes a waterproof membrane that can be installed on a substrate. The membrane comprises a textile layer and a resin layer on both surfaces.

[0010] It is therefore an object of the invention to propose a geomaterial sheet, a method for stabilizing soil layers with a geomaterial sheet and uses of geomaterial sheets for stabilizing soil layers, which ensure reliable mechanical stabilization over the necessary period of use, but at the same time reduce the environmental impact.

[0011] This object is achieved according to a first aspect of the invention by a geomaterial sheet according to claim 1

[0012] According to the invention, a geomaterial web is proposed that consists of a first and second structural material or comprises such a first structural material and a second structural material. The first and second structural materials are joined together to form a flat composite material web, i.e., a geotextile, a mat, or the like. This joining can be achieved by weaving, knitting, nonwoven processing, or other methods that systematically join the first and second structural materials together. The first and second structural materials can preferably be fiber materials, which include short fibers, long fibers, yarns, continuous fibers, and the like. The connection between the first and second structural materials can also be designed in the manner of a nonwoven material, in that intertwining and entanglement effects of the fibers are achieved through a random alignment of fibers.

[0013] According to the invention, the first structural material is an organic structural material, for example, wood, wood-based materials, or plastics. The second structural material can be either an organic or an inorganic material. The functionality and effectiveness of the geomaterial sheet are achieved through the interaction of the two structural materials.

[0014] Both the first and second structural materials are biodegradable. According to the invention, biodegradability is defined according to the principle of ISO 16929 or according to a marine degradation test developed by TÜV Austria Belgium. The material according to the invention must meet at least one of these two conditions, preferably both.

[0015] According to ISO 16929, a material is considered compostable if it meets three criteria. One of these criteria is defined as no more than 10% by weight of the material remaining in a 2mm sieve after 84 days of controlled composting when the material or its components are sieved. Based on this system and adapted to the needs of geomaterials, the first structural material demonstrates initial biodegradability: within six months of controlled composting according to ISO 16929 under thermophilic composting conditions, no more than 50% by weight of the dry mass of the first structural material remains in the sieve after sieving through a 2mm sieve. The first material therefore does not necessarily qualify as compostable within the meaning of ISO 16929. However, it can be compostable or it can achieve degradation to 90% by weight of particles <2mm over a period longer than six months.

[0016] The degradation test under marine conditions simulates the degradation of standardized samples under an accelerated simulation in seawater. Here, too, the degree of degradation is determined by a final sieving based on the dry weight remaining in the sieve. However, the more intensive mobility of the material is simulated by two intermediate sievings after 4 and 8 weeks.

[0017] Both degradation tests are conducted using test specimens with defined dimensions. Length and width are defined, and thickness is based on the original material, i.e., the thickness of the material in the produced construction. For layered composites, in which the first and second structural materials are arranged and bonded together in separate, superimposed layers, this can be the thickness of the material in the respective layer. If the original material is produced as a composite layer, such as a nonwoven or as a layer made of two different fibers woven, knitted, or otherwise bonded, a sample of the material in the original material thickness of the layer must be used for the purposes of the degradation test, and this sample is made solely from the material being tested.

[0018] Compared to the first structural material, the second structural material exhibits a second biodegradability that is different, in particular lower, than that of the first structural material. This means that after six months or twelve weeks, a second weight percentage of the second structural material remains in the 2 mm sieve, which is different, in particular higher, than that of the first structural material. For example, if in the composting test, 70% by weight of the first structural material is degraded into particles <2 mm within six months, a weight percentage of 60% of the second structural material can be degraded into particles <2 mm within the same period under the same conditions.

[0019] The invention therefore provides a geomaterial sheet that undergoes a defined material conversion into carbon dioxide through biodegradation, whereby one of the two structural materials contained in the geomaterial sheet or from which the geomaterial sheet is constructed biodegrades faster than the other. This allows both the geometric and mechanical properties of the geomaterial sheet to be specifically influenced by biodegradation.For example, the more rapid degradation of the first structural material in the geomaterial sheet can result in the formation of openings or pores that are advantageous for a rooting process, in that the increased space requirement of the plant roots that occurs with increasing rooting is provided by the biological degradation of the first structural material, while at the same time the necessary mechanical stabilization is maintained by the second structural material. Furthermore, for example, in the case of woven or knitted fabrics or nonwovens or composites made of the first and second structural materials, a mechanical property in a first direction, in which essentially the first structural material runs in the geomaterial sheet, can be reduced more than a mechanical property in a deviating second direction, in which essentially the second structural material runs in the geomaterial sheet.For example, in the case of slope stabilization, stability transverse to the slope direction can be reduced more quickly than stability in the slope direction, thus achieving the slight mobility of the geomaterial sheet desired for plant growth, but at the same time preventing slippage in the slope direction.

[0020] In principle, in addition to influencing the geometric and mechanical properties through the specific arrangement of the first and second structural materials in the geomaterial sheet, the mechanical properties over the degradation period of the geomaterial sheet can also be influenced by the selection and proportions of the first and second structural materials. This advantageously allows the biodegradation rate and reduction in mechanical / geometric properties to be adapted to local conditions at the installation site of the geomaterial sheet. While the standardized biodegradability is determined under standardized conditions, different influencing parameters for biodegradability can prevail at the installation site. For example, an increased oxygen content can lead to faster biodegradation and, conversely, a reduced oxygen content can lead to slower biodegradation.Furthermore, influencing factors such as increased UV radiation, a high or low pH value, an increased nutrient supply, an increased proportion of bacteria, an increased proportion of fungi, and other factors can influence the rate of biodegradation. Due to the possibility of changing the mixing ratio of the first and second structural materials in the geomaterial sheet according to the invention, the proportion of the second structural material can be increased, for example, if an increased biodegradation rate is to be expected due to local influencing factors at the installation site. Conversely, if influencing factors that reduce the biodegradation rate are to be expected at the installation site, this can be counteracted by increasing the proportion of the first structural material, in order to obtain a geomaterial sheet adapted to the local conditions with a tailored biodegradation rate.

[0021] It is preferably provided that the first biodegradability is greater than the second biodegradability. According to this embodiment, the second structural material has a lower biodegradability than the first structural material, i.e. the second structural material degrades more slowly than the first structural material. In principle, for example, the first structural material can have a degradability such that after six months or twelve weeks at least 90% by weight of the first structural material has degraded into particles smaller than 2 mm, whereas for the second structural material it is only 80% by weight or less. This means that for the first material less than 10% by weight of the material remains in the 2 mm sieve, whereas for the second material it is more than 20% by weight. Preferably, the second structural material has a biodegradability such that after six months less than 50% has degraded into particles smaller than 2 mm.

[0022] According to the invention, the first structural material is arranged in the geomaterial sheet in such a way that, after partial or complete biological degradation of the first structural material, openings are formed in the geomaterial sheet, penetrating the geomaterial sheet. Accordingly, the more rapid degradation of the first structural material changes the geometric appearance of the geomaterial sheet, creating openings penetrating the geomaterial sheet. The first structural material is therefore arranged in the geomaterial sheet in such a way that, in its initial state, it closes these openings and, as it degrades, opens these openings or creates these openings. The geomaterial sheet is thereby perforated, or perforated to a greater extent, and consequently adapts to a rooting process which, with increasing rooting, requires greater permeability of the geomaterial sheet, while, on the other hand, also requires lower mechanical strength of the geomaterial sheet.The desired effect of forming openings by degrading the first structural material can be achieved, for example, by processing the first and second structural materials together to form a nonwoven fabric.

[0023] It is further preferred that the first structural material partially or completely penetrates the second structural material. By means of such penetration, on the one hand, a specific, directed or undirected mechanical destabilization of the geomaterial sheet can be achieved through the biological degradation of the first structural material. On the other hand, specific directed or undirected channels and openings can be created in the second structural material through the biological degradation of the first structural material, which run along the penetration.

[0024] It is even further preferred that the first structural material and the second structural material are bonded to one another as a layered composite, that the second structural material has a plurality of second perforation openings and that the first structural material has no perforation openings, or that it has a plurality of first perforation openings that are smaller than the second perforation openings. This configuration ensures that larger openings can be created throughout the geomaterial sheet due to the faster decomposition of the first structural material.

[0025] A further aspect of the invention is a method for location-dependent soil stabilization by means of a geomaterial sheet, comprising the steps: Determining the intensity of an influencing parameter at the installation site, wherein the intensity of the influencing parameter is selected from: intensity of a radiation effect of electromagnetic radiation, level of a temperature, concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, concentration of a concentration of bacteria, and / or concentration of fungi,

[0026] Determining one or more of these influencing parameters at a location away from the installation site, Installing the geomaterial sheet at the installation site, wherein the geomaterial sheet comprises a structural material which ∘ under the intensity of the influencing parameter at the installation site has a biodegradability to the extent that within six months a residual portion of the material at the installation site remains in a sieve of 2 mm when the material or its components are sieved, ∘ wherein the residual portion of the material at the installation site is less than 30% by weight of the material, ∘ under the intensity of the influencing parameter at the installation site has a biodegradability to the extent that within six months a residual portion of the material at the installation site remains in a sieve of 2 mm when the material or its components are sieved, ∘ wherein the residual portion of the material at the installation site is greater than the residual portion of the material at the installation site.

[0027] According to this aspect of the invention, site-dependent soil stabilization is achieved using a geomaterial sheet. This means that the geomaterial sheet has a biodegradation period at the installation site and a different biodegradability at the delivery site, which, as before, can be defined, for example, analogously to the standardization of degradability according to ISO 16929 or the marine degradation test - but with the parameters determined at the installation site or delivery site. Depending on the conditions prevailing at the installation site, more than 10 wt.%, in particular more than 25 wt.% or more than 80 wt.% of the structural material may remain as particles in a 2 mm sieve after a period of six months or twelve weeks. This achieves a reduced biodegradation rate at the installation site, which is sufficient for numerous soil stabilization applications and ensures reliable degradation of the geomaterial sheet.This biodegradability is achieved under the conditions at the installation site, in particular the aforementioned influencing parameters of temperature, radiation exposure, oxygen, bacterial and / or fungal concentration or the like. In contrast, with the method according to the invention, the material exhibits higher biodegradability at a delivery site. Under the conditions there, fewer particles of the material remain in a 2 mm sieve after six months or twelve weeks than under the conditions at the installation site. At the delivery site, this can preferably be achieved with less than 80 wt. %, %, in particular less than 25 wt. % or less than 10 wt. % of the structural material within the six months or twelve weeks under the conditions prevailing there with a higher degradation rate.

[0028] The disposal site can be a location where the geomaterial sheet is transported after removal from the installation site, for example, where it is deposited, and which differs from the installation site with regard to one of the influencing parameters. For example, a deliberately created higher oxygen concentration and / or stronger UV radiation and / or bacterial and / or fungal concentration may prevail at the disposal site and cause accelerated biological degradation of the geomaterial sheet. The disposal site can also be a location to which the geomaterial sheet arrives, either in its entirety or in fragments, if it is exposed or mechanically attacked by environmental or other influences and then, for example, becomes exposed, floats, or is transported by other influences.A "disposal site" can also be understood as a change in the original installation of the geomaterial sheet at the installation site beneath a soil layer, resulting in the soil layer being eroded and the geomaterial sheet being exposed. This is the case, for example, in many marine applications for coastal protection and scour control, where water and wave movements can cause the material to be separated and transported from the installation site to a disposal site. At the disposal site, the geomaterial sheet degrades at an accelerated rate and therefore does not pose a significant environmental impact.

[0029] It is preferred if the installation site has an environment with a lower temperature and / or a lower oxygen content and / or lower bacterial and / or fungal concentration than the disposal site. These influencing parameters are particularly well suited for viscose-based geomaterial sheets such as lyocell, in order to achieve the different biodegradation rates at the installation site compared to the disposal site.

[0030] In particular, the installation site may be located on the seabed, and the geomaterial sheet may float due to currents and / or density differences, or it may reach the surface due to anthropogenic influences. The installation site is therefore characterized by higher oxygen concentrations and temperatures in the upper water layers, as well as increased UV radiation, which accelerate degradation.

[0031] It is even more preferred if the structural material is a viscose-based material, especially lyocell. Such a structural material has proven particularly suitable for selectively accelerated biodegradation rates at the delivery site compared to the installation site.

[0032] According to this aspect of the invention, the geomaterial sheet is thus used in such a way that it comprises a structural material which under a first intensity of an influencing parameter at an installation site, has a biodegradability to the extent that in a composting test with the following parameters ∘ samples with a length of 10 cm, a width of 10 cm and an original material thickness ∘ 50 ° C + / − 5 ° C ∘ thermophilic conditions according to ISO 16929, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ sieving of the solids after six months in a sieve with 2mm mesh size (mesh 8.75) during sieving more than 50 dry weight % of the starting material remains in the sieve, or in a marine incubation test, with the following parameters: ∘ samples with a length of 2cm, a width of 2cm and an original material thickness ∘ 30 ° C + / − 2 ° C ∘ Aerobic conditions in seawater with a salinity of 3.5 wt% + / - 1 wt%, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ Sieving of the solids after 4, 8 and 12 weeks in a sieve with a mesh size of 2 mm (mesh 8.75) when sieving after 12 weeks more than 10 dry weight%, in particular more than 25 dry weight% or more than 80 dry weight% of the starting material remains in the sieve, and under a second intensity of the influencing parameter at a place of installation, has a biodegradability to the extent that within six months in the composting test or twelve weeks in the marine incubation test and less than 80 wt.%, in particular less than 25 wt.% or less than 10 wt.% of the dry mass of the first structural material remains in the sieve after sieving through a 2 mm sieve, whereby the intensity of the influencing parameter is selected from: an intensity of radiation exposure, an electromagnetic radiation, a level, a temperature, a concentration of a substance that reacts chemically and / or biochemically with the geomaterial sheet, a concentration of bacteria, a concentration of fungi, in such a way that the geomaterial sheet is installed at an installation time at the installation site and is transported to the place of installation at a later time following the installation time.

[0033] According to this use, a geomaterial sheet is deployed in such a way that it exhibits a predetermined degradation rate at an installation site that does not exceed a certain biological degradation rate, which is achieved by the aforementioned influencing parameters prevailing there. In contrast, the geomaterial sheet is deployed in such a way that when it is transported from the installation site to a disposal site, which can be done by scheduled transport or unscheduled shipment, it exhibits a higher degradation rate and thus biodegrades more quickly at the disposal site than at the installation site. This accelerated degradation is achieved by the degradation rate being dependent on the intensity of an influencing parameter - gfs - that varies there.also by several different influencing parameters that prevail with different intensities at the installation site and at the disposal site - and which are used as influencing parameters instead of the specified parameters in the previously defined material tests for composability and marine degradation.

[0034] Another aspect of the invention relates to the use of a geomaterial sheet comprising a structural material which under a predetermined intensity of an influencing parameter at an installation site, has a biodegradability to the extent that in a composting test with the following parameters: o Samples with a length of 10 cm, a width of 10 cm and an original material thickness ∘ 50 ° C + / − 5 ° C ∘ thermophilic conditions according to ISO 16929, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ sieving of the solids after six months in a sieve with a mesh size of 2 mm (mesh 8.75) during sieving less than 50 dry weight % of the starting material remains in the sieve, or in a marine incubation test, with the following parameters: ∘ samples with a length of 2 cm, a width of 2 cm and an original material thickness ∘ 30 ° C + / − 2 ° C ∘ Aerobic conditions in seawater with a salinity of 3.5 wt% + / - 1 wt%, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ Sieving of the solids after 4, 8 and 12 weeks in a sieve with a mesh size of 2 mm (mesh 8.75) when sieving after 12 weeks less than 20 dry weight% of the starting material remains in the sieve. wherein the predetermined intensity of the influencing parameter is selected from: an intensity of a radiation effect of an electromagnetic radiation, a height of a temperature, a concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, a concentration of bacteria, a concentration of fungi, for stabilizing a soil layer in flood protection or scour protection.

[0035] According to this aspect of the invention, a geomaterial sheet, in particular a geomaterial sheet of the type described above, is used to achieve soil stabilization for scour protection or flood protection. Flood protection can be provided in any type of bank reinforcement on the seashore, on the banks of flowing and standing waters and lakes, whereby the geomaterial sheet can be arranged in the area below the water surface or above the water surface, with the option of drying out or becoming wet. In this case, it serves to stabilize the bed, slope, or dike and can be used permanently or temporarily during construction work until a sufficient degree of root penetration by vegetation is achieved. Scour protection is understood here as protection against the displacement of soil material by currents. Here, too, permanent or temporary protection of the soil can be provided by the geomaterial sheet.In particular, such scour protection can be achieved, for example, by flexible containers made of the geomaterial sheet filled with particulate material such as sand or the like, which are placed on the soil layer to be stabilized.

[0036] The geomaterial sheet is used in such a way that targeted biodegradation is achieved. This targeted biodegradation can, on the one hand, consist of biodegradability occurring at the installation site itself, unlike in previously known applications, and the geomaterial sheet therefore disintegrating as planned within a certain period of time. Biodegradability can also be designed such that the geomaterial sheet is more biodegradable at a disposal site than at the installation site. This ensures that if the geomaterial sheet is intentionally or unintentionally transported away from the installation site, it biodegrades more quickly at a disposal site with different influencing parameters and thus poses no environmental impact.

[0037] Preferably, the geomaterial sheet is used to manufacture fillable containers, and these containers are used in such a way that they are placed filled on the seabed, thereby providing scour protection in areas subject to current stress. This development achieves particularly effective scour protection.

[0038] The use can be further developed by installing the geomaterial sheet in bank or coastal protection at an installation site subject to occasional drying out or at an installation site subject to occasional wetting. The geomaterial sheet preferably has a lower density than water. Particularly in the case of occasional drying out or wetting, unintentional release of a geomaterial sheet during such reinforcement measures can occur, and the special property of biological degradation can then have a beneficial effect.

[0039] A further aspect of the invention is a method for soil stabilization by means of a geomaterial sheet, comprising the steps: a) determining a soil parameter value characterizing a soil property at an installation site, b) determining a degradation value characterizing a biodegradation rate, c) selecting a mixing ratio of a first and second structural material which have different biodegradability based on the soil parameter value and the degradation value, d) combining the first and second structural material to form a geomaterial sheet in the mixing ratio, e) providing the geomaterial sheet for installation at the installation site.

[0040] According to this aspect of the invention, soil stabilization is carried out at an installation site by providing a geomaterial sheet for installation in the soil layer at the installation site. For this purpose, soil properties must be known. This means that at least one property of the soil that influences biodegradability in a relevant way is determined or measured. For example, the soil moisture content, pH value, nutrient concentration, the presence of bacteria and fungi, and / or the soil temperature can be assumed or determined as the average temperature over a daily, weekly, monthly, or annual period. Furthermore, the intensity of UV radiation at the installation site can be measured.

[0041] These installation-site-specific parameters take into account the parameters influencing the biological degradation process that prevail at the installation site. A characteristic value can be determined from these parameters, for example, as a dimensionless factor or as an empirical value from tables. For example, the previously explained compostability or degradation under marine conditions defined according to ISO 16929 can serve as a standard reference value, and the degradation value can be defined in relation to this reference value, for example, by characterizing a percentage-lower degradation property due to soil properties by a corresponding percentage below 100%, or by characterizing a higher biological degradation rate at the installation site by the degradation value, by using a value above 100% as the degradation value.

[0042] Furthermore, a degradation value is determined which defines the period of time within which a certain degree of biological degradation of the geomaterial sheet or a component of the geomaterial sheet should be achieved.

[0043] Based on the soil parameter value and the degradation value, a mixing ratio of a first to a second structural material is then selected. The first and second structural materials exhibit different biodegradability or degradation rates at the soil parameter value. The mixing ratio can provide an overall achieved biodegradation rate of the geomaterial sheet, which is constructed from the first and second structural materials. This biodegradation rate depends on the soil parameter value assumed or measured at the installation site and should be selected such that the desired degradation value, which describes the rate of biodegradation of the geomaterial sheet, is achieved.

[0044] After selecting the mixing ratio, the first and second structural materials are combined to form the geomaterial sheet. This bonding can be done as a nonwoven, knitted, warp-knitted, or other form and is intended to bond the first and second fibrous materials together in a mechanically resilient manner. The resulting geomaterial sheet is therefore tailored for use and targeted biodegradation at the installation site and under the prevailing conditions.

[0045] This solution ensures that the geomaterial sheet biodegradation is neither too rapid nor too slow by incorporating the soil parameters that influence biodegradation into the design of the geomaterial sheet. A targeted degradation behavior, characterized by the degradation value, is achieved by a mixing ratio of two fiber materials.

[0046] The method can be further developed by specifying the soil parameter value as a soil moisture content at the installation site, for example, between 3 and 300 wt.%, a soil pH value at the installation site, for example, between 1 and 13, an enzyme concentration in the soil at the installation site, a temperature between 4°C and 50°C, or a soil characteristic value formed from several of these soil parameter values. These soil parameter values ​​are used to determine significant influencing factors on the biodegradation rate of typical fiber materials, such as viscose fibers like Lyocell, and can therefore be used to design the geomaterial sheet with a biodegradability tailored to the installation site.

[0047] It is particularly preferred if the degradation value is a strength quotient formed from the ratio of a mechanical strength value to an installation time of the geomaterial sheet compared to the initial value, a permeability quotient formed from the ratio of a porosity to an installation time of the geomaterial sheet compared to the initial value, or a degradation characteristic value formed from several of these degradation values. According to this embodiment, the degradation value is defined either as a strength quotient or as a permeability quotient or as a degradation characteristic value calculated from the strength quotient and the permeability quotient. The strength quotient characterizes the decrease in the mechanical strength of the geomaterial sheet over the residence time of the geomaterial sheet in the soil.This strength quotient is calculated from the ratio of the mechanical strength value at the time of installation, i.e., before biological degradation has occurred, to the mechanical strength value after a predetermined residence time, which can, for example, be standardized to three or six months and characterizes the mechanical strength after biological degradation has occurred to a certain degree. Similarly, the permeability quotient is determined by setting a porosity at the beginning, i.e., at the time of installation, in relation to a porosity after biological degradation has occurred over a predetermined period. Through this characterization of the degradation values, the desired properties can be specifically determined and consequently influenced by selecting the appropriate material. A strength quotient lies in the range of 1.0 to 0 and is typically 0.25, i.e.,The strength at a defined point in time after biodegradation has occurred is reduced fourfold compared to the initial value. A typical permeability quotient is in the range of one to four orders of magnitude and is ideally > 10, i.e., the permeability has increased tenfold compared to the initial value at a defined point in time after biodegradation has occurred.

[0048] The geomaterial sheet described above, the specific uses described above, and the methods for their application can be further developed by the geomaterial sheet having a polymer group comprising a molecule provided with an isotopic label, in particular a 13< C or 18< O isotopic label. According to this further development, the geomaterial sheet is provided with an isotopic label and can therefore be clearly identified even in a later, possibly fragmented form. In this way, any environmental pollution that may occur can be unequivocally attributed or excluded, and the cause of such environmental pollution can be quickly and reliably identified.

[0049] Furthermore, the method, use, and geomaterial sheet can be further developed by having the geomaterial sheet comprise a structural material or consist of one or more structural materials that are metabolizable. Such metabolism by living organisms, such as mammals, fish, or microorganisms such as microbes, leads to the reintegration of the geomaterial sheet into the biocycle and thus to environmentally safe disposal. Metabolism can preferably occur on fragments such as shredded fiber residues of the geomaterial sheet. Metabolism in this context means, on the one hand, the biologically harmless compatibility of the geomaterial sheet for living organisms, and, furthermore, the ability of the geomaterial sheet to be chemically altered and degraded during the metabolic processes in the digestive tract of a living organism.

[0050] Furthermore, it is preferred if the geomaterial web is formed by a single- or multi-layer filter nonwoven fabric made of at least two different structural materials that are bonded together to form a nonwoven fabric, wherein A first structural material under a predetermined intensity of an influencing parameter at an installation site has a biodegradability to the extent that in a composting test with the following parameters: ∘ Samples with a length of 10 cm, a width of 10 cm and an original material thickness ∘ 50 ° C + / − 5 ° C ∘ thermophilic conditions according to ISO 16929, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ sieving of the solids after six months in a sieve with a mesh size of 2 mm (mesh 8.75) where less than 80 wt.%, in particular less than 25 wt.% or less than 10 wt.% of the dry mass of the first structural material remains in the sieve after twelve weeks, or in a marine incubation test, with the following parameters: ∘ samples with a length of 2 cm, a width of 2 cm and an original material thickness ∘ 30 ° C + / − 2 ° C ∘ Aerobic conditions in seawater with a salinity of 3.5 wt% + / - 1 wt%, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ Sieving of the solids after 4, 8 and 12 weeks in a sieve with a mesh size of 2 mm (mesh 8.75) when sieving after 12 weeks less than 80 wt%, in particular less than 25 wt% or less than 10 wt% of the dry mass of the first structural material remains in the sieve when sieving after twelve weeks. wherein the predetermined intensity of the influencing parameter is selected from: an intensity of a radiation effect of electromagnetic radiation, a level of a temperature, a concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, a concentration of bacteria, a concentration of fungi, and a second structural material is connected to the first structural material to form the filter nonwoven fabric, wherein the second structural material, under the same predetermined intensity of the influencing parameter at the same installation location, has a lower biodegradability to the extent that within six months under the same conditions a larger wt. % of the dry mass of the second structural material remains in the sieve after six months or twelve weeks when sieved through a 2 mm sieve than with the first structural material.According to this advanced development, the geomaterial sheet is designed as a nonwoven fabric consisting of two different structural materials that exhibit different biodegradation rates under given, predetermined parameters. This allows the nonwoven fabric to undergo targeted mechanical structural weakening through the biodegradation process, while also undergoing geometric changes with pore formation, perforation, or the like, for example, to promote root penetration.

[0051] A further development provides for the geomaterial sheet, the process for its production or its installation and its use to be developed so that the geomaterial sheet is installed as an element in structures that serve to influence air currents, in such a way that in particular the speed of the air flow is locally reduced for the purpose of deposition of particles that are transported suspended, bounce or roll in the air if the air speed is not reduced. The geomaterial sheet, the use and the process thus serve the deposition of minerals, in particular sand, for example on coastal sections that are at risk from sand erosion. The reduction in air speed leads to the deposition of sand, preferably to the lee of the structures. The structure is thereby partially or completely encased in sand.The geomaterial sheet according to the invention thus becomes part of the sand deposit and can be dismantled according to the invention at the place of installation or disposal, provided that the structure can be dismantled within the sand deposit according to the invention or, if the structure is exposed again due to a change in the erosion conditions.

[0052] Preferred embodiments are explained with reference to the figures. They show: Fig. 1 is a schematic representation of a use of the geomaterial sheet according to the invention in three different arrangements for coastal protection, Fig. 2a is a use of the geomaterial sheet according to the invention for slope stabilization at two different root penetration times, Fig. 3 is a schematic representation of a first embodiment of the geomaterial sheet according to the invention, Fig. 4 is a schematic representation of a second embodiment of the geomaterial sheet according to the invention, Fig. 5 is a schematic representation of a third embodiment of the geomaterial sheet according to the invention, Fig. 6 is a schematic representation of a fourth embodiment of the geomaterial sheet according to the invention.

[0053] The geomaterial sheet according to the invention can basically be installed in three different installation situations with regard to water contact in the embankment area. Starting from a natural shore area 2, bordered by the waterline or, in the case of tidal waters, the average water level, and possibly protected against flooding by an artificial dike 3, a geomaterial sheet can initially be deployed in an installation position A to stabilize the underwater terrain of the natural seabed, where stabilization of the soil with plants is only inadequately possible. In this installation position A, the geomaterial sheet is generally underwater and can, in exceptional cases, dry out during low tide or heavy waves.

[0054] In a second installation position B, the geomaterial sheet is installed on the waterside to reinforce the natural bank slope and / or the artificial dike slope. In this installation position, the geomaterial sheet stabilizes the generally dry bank portion of the natural slope and, if applicable, the artificial dike slope. It is therefore generally dry, but can also be submerged in water during flooding or heavy waves.

[0055] In a third installation position (C), the geomaterial sheet is installed in an area, such as the back of the dike, where it is not exposed to the water itself and can only be subjected to stress in special situations such as overflow. In this installation position, the geomaterial sheet is therefore always dry and, as in any installation position, is only exposed to wetting by rainfall.

[0056] Each of the three installation positions requires differently coordinated behavior of geomaterial sheets in order to achieve ecologically favorable behavior. In installation position A, stability of the geomaterial sheet in an aqueous environment is required. However, if parts of this geomaterial sheet become detached due to abrasive events and are therefore no longer in the place required to fulfill their function, degradation of these detached geomaterial sheet components is desired. According to the invention, this can be achieved, for example, by forming the geomaterial sheet from a material that degrades rapidly under the influence of UV radiation. This ensures that floating or washed ashore, torn-off parts of the geomaterial sheet undergo rapid degradation, whereas at the installation site, when no UV radiation hits the geomaterial sheet, the mechanical stability is maintained.Instead of specifying the geomaterial sheet for UV radiation, for example, a specification of biodegradability can also be made depending on the oxygen content of the water and / or the bacterial and / or fungal concentration in certain applications. This is particularly suitable when geomaterial sheets are used at great depths, where low concentrations of the aforementioned influencing parameters prevail. In this case, the material of the geomaterial sheet can be designed to be mechanically stable in the planned installation situation and the surrounding water and to biodegrade as soon as the concentration of influencing parameters in the surrounding water or at the installation site increases.

[0057] The installation situation according to C is relevant for the invention, for example, with regard to root penetration and the adaptation of the geomaterial sheet to root penetration processes. Fig. 2a und b show two temporally successive rooting situations in which a geomaterial sheet 10 is installed to stabilize a soil layer 20 at a certain depth of the soil. Fig. 2a As can be seen, at an early stage, shortly after the establishment of soil-stabilizing plants, the geomaterial sheet 10 has a high density with only small openings, thus providing high mechanical stabilization of the soil. The planted plants can penetrate the geomaterial sheet with small root shoots and are not hindered in their growth. An effective mechanical bond between the geomaterial sheet and the plants is already achieved at this early stage.

[0058] Fig. 2b shows the same installation situation after several weeks of plant growth. The geomaterial sheet has partially decomposed mechanically through biological degradation. It has larger openings and lower mechanical stability. Due to the larger openings, the growing plants are not hindered in their root penetration and the increase in root diameter and can therefore assume the mechanical stabilization function. With the geomaterial sheet according to the invention, a continuous shift of the mechanical stability of the soil layer from the geomaterial sheet to the plants is achieved, while at the same time a good mechanical connection between the plants and the geomaterial sheet is maintained and the geomaterial sheet continues to have mechanical properties, possibly in different directions, and assumes functions to stabilize the soil.

[0059] Fig. 3 bis 6 show exemplary embodiments of a geomaterial sheet. In principle, the geomaterial sheets according to the invention can be provided in different widths and lengths. Typical widths are greater than 1 m, 1.5 m or 2 m and less than 4 m, 5 m or 6 m and typical lengths are longer than 2 m, 5 m, 10 m, 50 m, whereby the geomaterial sheet can preferably be transported in a rolled-up state and is unrolled during installation. The thickness of the geomaterial sheet can be greater than 1 mm, with thicknesses of more than 5 mm, 10 mm or more than 20 mm being preferred. The geomaterial sheet can have a basis weight that is greater than 150, greater than 300 or greater than 500 g / m 2 . The basis weight can be less than 1500, less than 2000 g / m 2 or less than 2500 g / m 2 .

[0060] Fig. 3 shows a first embodiment with a cover layer 110, a carrier layer 120 and a middle layer 130 arranged between cover layer 110 and carrier layer 120. Cover and carrier layers 110 and 120 can be made of different or identical materials and the intermediate layer 130 can be designed to match the cover layer and carrier layer or can be made of a different material.

[0061] The cover layer and the carrier layer are connected to one another by means of needling, sewing or knitting. For this purpose, several needling holes 140a, b, c are introduced into the geomaterial sheet, which connect the cover layer to the carrier layer through the intermediate layer 130. In this embodiment of a geomaterial sheet, for example, the cover layer can consist of a material that is biologically degraded more quickly than the carrier layer 120. This creates channels after partial or complete biological degradation of the needling, sewing or knitting parts of the geomaterial sheet, which extend from the top to the bottom of the geomaterial sheet and, for example, provide space for root penetration or drainage effects.

[0062] Fig. 4 shows a second embodiment of a geomaterial sheet comprising an upper grid layer 210 and an underlying nonwoven layer 220. The grid layer 210 is formed by a cross-shaped grid of strong individual fibers or rods that form grid openings of a specific size, for example, 10 x 10 mm to 40 x 40 mm. The nonwoven layer is formed of dense, randomly oriented fibers of a different material than layer 210. This nonwoven layer overall closes the openings of the grid layer 210, resulting in a geomaterial sheet that is impermeable to coarser particles and permeable to liquids and gases. The nonwoven layer 220 is made of a material such as lyocell and biodegrades faster than the grid layer 210.As a result, the mechanical strength of the geomaterial sheet is reduced within the short biological degradation time of the fleece layer 220 and, after degradation of the fleece layer 220, the geomaterial sheet is reduced to the remaining grid layer 210 with the openings formed therein, which in turn provide appropriate space for favorable root penetration.

[0063] Fig. 5 shows a third embodiment, which is basically designed as a single-layer geomaterial web. In the geomaterial web, fibers 310 of a first material are arranged in a first direction and fibers 320 are arranged in a second direction, transverse to the first direction, thereby forming fiber layers. The fibers 310 and 320 can be connected to one another, for example by welding, gluing, interlacing, needling, weaving or knitting techniques and / or by means of a cover and carrier layer above and below the fibers 310 and 320. The fibers 310 are made of a different material than the fibers 320, wherein the material from which the fibers 320 are formed is biodegradable more quickly than the material from which the fibers 310 are formed.Due to this biological degradation behavior of the geomaterial sheet, the geomaterial sheet initially has a load-bearing capacity in the longitudinal and transverse directions, corresponding to the direction of the fibers 310, 320. With increasing biological degradation of the fibers 320, the strength and load-bearing capacity in the longitudinal direction along the direction of the fibers 320 decreases, resulting in an anisotropic mechanical load behavior of the geomaterial sheet.

[0064] Fig. 6shows a fourth embodiment in which two different materials are processed into a nonwoven layer, which represents a geomaterial web or can represent a layer of a geomaterial web. The two different materials 410, 420 are processed into a nonwoven in an unoriented manner as short or long fibers or continuous fibers and bonded together. Material 420 biodegrades faster than material 410, whereby the density of the geomaterial web decreases with increasing biodegradation in the installation situation and the geomaterial web becomes more permeable and / or changes its mechanical properties.

[0065] In principle, it should be understood that the four exemplary embodiments can also be combined with one another by producing multi-layer geomaterial webs that have combined properties of these exemplary embodiments. Furthermore, it should be understood that the four exemplary embodiments can also be combined in such a way that their properties are combined in a single layer of a geomaterial web, for example, by forming the lattice structure 210 of the second embodiment with the anisotropically biodegradable fibers 310, 320 of the third embodiment.

[0066] The biodegradation behavior can generally be adjusted at the installation site and adapted to the prevailing conditions there. In all embodiments, the proportion of one material relative to the proportion of another material can be increased or decreased to achieve the desired biodegradation behavior tailored to the prevailing conditions. Furthermore, the biodegradation properties can be influenced or even triggered by external influences such as UV radiation and / or oxygen content and / or concentration of bacteria, fungi, or chemical influences in the environment, resulting in a specific behavior of the geomaterial sheets with regard to biodegradation when they are moved from one location to another where these specific environmental conditions change.

Claims

1. Geomaterial web, comprising - a first organic structural material and a second structural material, different from the first, which is connected to each other with the first structural material to form a planar composite material web extending in two mutually perpendicular directions, characterized in that the first structural material is an organic material and the second structural material is an organic or inorganic material, - the first structural material has a first biodegradability to the extent that - In a composting test with the following parameters: ∘ Samples with a length of 10 cm, a width of 10 cm and an original material thickness ∘ 50 ∘ C + / − 5 ∘ C ∘ thermophilic conditions according to ISO 16929, ∘ Sieving out the solids after six months in a sieve with a mesh size of 2 mm (mesh 8.75) less than 80 % by weight, in particular less than 50 % by weight, less than 25 % by weight or less than 10 % by weight of the dry mass of the starting material remains in the sieve during sieving, or - in a marine incubation test, with the following parameters: ∘ Samples with a length of 2 cm, a width of 2 cm and an original material thickness ∘ 30 ∘ C + / − 2 ∘ C ∘ aerobic conditions in seawater with a salt content of 3.5 wt.% + / - 1 wt.%, ∘ Sieving out the solids after 4, 8 and 12 weeks in a sieve with a mesh size of 2 mm (mesh 8.75) less than 80 % by weight, in particular less than 50 % by weight, less than 25 % by weight or less than 10 % by weight of the dry mass of the starting material remains in the sieve after 12 weeks, and the second structural material has a second biodegradability which is different from the first biodegradability, in particular is lower than the first biodegradability and in that the first structural material is arranged in the geomaterial web in such a way that, after partial or complete biodegradation of the first structural material, openings are formed in the geomaterial web passing through the geomaterial web,2. Geomaterial web according to claim 1, characterized in that the first structural material partially or completely penetrates the second structural material, or the first structural material and the second structural material are bonded together as a layered composite, the second structural material has a plurality of second perforation openings and the first structural material has no perforation openings, or has a plurality of first perforation openings which are smaller than the second perforation openings.

3. Geomaterial web according to any of the preceding claims 1-2, characterized in that - the geomaterial web has a polymer group comprising a molecule provided with an isotopic label, in particular a 13C or 18O isotopic label, and / or - the geomaterial web comprises a structural material or consists of one or more structural materials that are metabolizable.

4. Geomaterial web according to any of the preceding claims 1-3, characterized in that the geomaterial web is formed by a single-layer or multi-layer nonwoven filter fabric which is produced from at least two different structural materials which are connected together to form a nonwoven, wherein - a first structural material exhibits biodegradability under a predetermined intensity of an influencing parameter at an installation site to the extent that a percentage by weight of more than 50%, in particular more than 75%, of the structural material is converted into carbon dioxide in the aqueous medium within six months, where the predetermined intensity of the influencing parameter is selected from: - Intensity of a radiation effect of electromagnetic radiation, - Height of a temperature, - Concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, - Concentration of a concentration of bacteria, - Concentration of fungi, - and a second structural material is connected to the first structural material to form the nonwoven filter fabric, the second structural material exhibiting biodegradability under the same predetermined intensity of the influence parameter at the same installation site to the extent that - in a composting test with the following parameters: ∘ Samples with a length of 10 cm, a width of 10 cm and an original material thickness ∘ 50 ∘ C + / − 5 ∘ C ∘ thermophilic conditions according to ISO 16929, ∘ Sieving out the solids after six months in a sieve with an ash width of 2 mm (mesh 8.75) - less than 50 % by dry weight of the starting material remains in the sieve during sieving, or - in a marine incubation test, with the following parameters: ∘ Samples with a length of 2 cm, a width of 2 cm and an original material thickness ∘ 30 ∘ C + / − 2 ∘ C ∘ aerobic conditions in seawater with a salt content of 3.5 wt.% + / - 1 wt.%, ∘ Sieving of the solids after 4, 8 and 12 weeks in a sieve with 2 mm mesh size (mesh 8.75), less than 20 % by dry weight of the starting material remains in the sieve after 12 weeks.

5. Method for site-dependent soil stabilization by means of a geomaterial web according to claim 1, comprising the steps: Design of the product for the influencing parameters determining the durability of the geomaterial at the installation site, whereby the influencing parameters are selected from: - Intensity of a radiation effect of electromagnetic radiation, - Height of a temperature, - Concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, - Concentration of a concentration of bacteria, - Concentration of fungi, Determination of one or more of these influencing parameters at a transfer site at a distance from the installation site, - Installation of the geomaterial sheet at the installation site, wherein the geomaterial sheet comprises a structural material which ∘ shows biodegradability under the intensity of the influence parameter at the transfer site to the extent that a transfer site residual portion remains in a sieve with a mesh size of 2 mm within six months if the material or its components are sieved, ∘ wherein the transfer site residual portion of the material is less than 80 wt.%, preferably less than 25 wt.% or less than 10 wt.% of the material, ∘ exhibits biodegradability under the intensity of the influence parameter at the installation site to the extent that within six months an installation site residual portion of the material remains in a sieve of 2 mm when the material or its components are sieved, ∘ where the installation site residual portion is greater than the transfer site residual portion, where preferably the installation site has an environment with a lower temperature, radiation, oxygen, bacteria and / or fungi concentration than the transfer site.

6. Method according to claim 5, characterized in that the installation site is on the seabed and the geomaterial sheet floats or is moved in seawater as a result of a current and / or density differences.

7. The method according to any one of claims 5-6, characterized in that the structural material is a viscose-based material, in particular lyocell.

8. Use of a geomaterial sheet according to claim 1, comprising a structural material which - exhibits biodegradability under a first intensity of an influencing parameter at an installation site to the extent that - in a composting test with the following parameters: ∘ Samples with a length of 10 cm, a width of 10 cm and an original material thickness, ∘ 50 ∘ C + / − 5 ∘ C ∘ thermophilic conditions according to ISO 16929, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ Sieving out the solids after six months in a sieve with a mesh size of 2 mm (mesh 8.75) - more than 80 % by dry weight, 25 % by dry weight, 10 % by dry weight of the starting material remains in the sieve during sieving, or that - in a marine incubation test, with the following parameters: ∘ Samples with a length of 2 cm, a width of 2 cm and an original material thickness ∘ 30 ∘ C + / − 2 ∘ C , ∘ Aerobic conditions in seawater with a salt content of 3.5 wt.% + / - 1 wt.%, unless these are defined by specific intensities of specific influencing parameters at the installation site, ∘ Sieving of the solids after 4, 8 and 12 weeks in a sieve with 2 mm mesh size (mesh 8.75), - more than 80 % by dry weight, more than 25 % by dry weight, 10 % by dry weight of the starting material remains in the sieve after 12 weeks, and - exhibits biodegradability under a second intensity of the influencing parameter at a transfer site to the extent that within six months in the composting test or twelve weeks in the marine incubation test less than 80 % by weight, in particular less than 25 % by weight or less than 10 % by weight of the dry mass of the first structural material remains in the sieve after sieving through a sieve with a mesh size of 2 mm, where the intensity of the influencing parameter is selected from: - Intensity of a radiation effect of electromagnetic radiation, - Height of a temperature, - Concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, - Concentration of a concentration of bacteria, - Concentration of fungi, - expected mechanical stresses in such a way that the geomaterial web is installed at the installation site at one time and transferred to the transfer site at a later time following the installation time.

9. Use of a geomaterial sheet according to any of claims 1-4 for installation in a soil layer for the purpose of soil stabilization.

10. Use of a geomaterial web according to claim 1, comprising a structural material which - exhibits biodegradability under a predetermined intensity of an influencing parameter at an installation site to the extent that - in a composting test with the following parameters: ▪ Samples with a length of 10 cm, a width of 10 cm and an original material thickness, ▪ 50 ∘ C + / − 5 ∘ C ▪ thermophilic conditions according to ISO 16929, ▪ Sieving out the solids after six months in a sieve with a mesh size of 2 mm (mesh 8.75) less than 50 % by dry weight of the starting material remains in the sieve during sieving, or - in a marine incubation test, with the following parameters: ▪ Samples with a length of 2 cm, a width of 2 cm and an original material thickness ▪ 30 ∘ C + / − 2 ∘ C ▪ Aerobic conditions in seawater with a salt content of 3.5 wt.% + / -1 wt.%, ▪ Sieving of the solids after 4, 8 and 12 weeks in a sieve with 2 mm mesh size (mesh 8.75), less than 20 % by dry weight of the starting material remains in the sieve after 12 weeks, where the predetermined intensity of the influencing parameter is selected from: - Intensity of a radiation effect of electromagnetic radiation, - Height of a temperature, - Concentration of a substance that reacts chemically and / or biochemically with the geomaterial web, - Concentration of a concentration of bacteria, - Concentration of fungi, - expected mechanical stresses. for stabilizing a soil layer in flood protection or scour protection.

11. Use according to claim 10, - characterized in that the geomaterial web is used to make fillable containers and the containers are used so that they are placed filled on the seabed and thereby provide scour protection at locations exposed to currents, or - the geomaterial sheeting is installed in bank or coastal protection at an installation site with occasional drying or an installation site with occasional wetting, whereby the geomaterial sheeting preferably has a lower density than water.

12. Use according to claim 10, characterized in that the geomaterial web is installed as an element in structures which serve to influence air flows in such a way that, in particular, the speed of the air flow is reduced locally for the purpose of depositing particles which are transported suspended in the air, bounce or roll when the air speed is not reduced.