NL2012739B1 - Method for creating a stabilized soil wall. - Google Patents

Description

METHOD FOR CREATING A STABILIZED SOIL WALL

Field of the invention [0001] The present invention relates to a method for creating a stabilized soil wall.

Background of the invention [0002] A wall created with such a method is generally known as a wall comprising ‘compressed stabilized earth blocks’ (CSEB) or a ‘rammed earth wall’. The method comprises the compression of a soil mixture under relatively high pressure within a compression space, either with or without the use of additional vibrations. The method allows the creation of wall elements or, if a plurality of such wall elements are arranged in a pattern next to or on top of each other, the creation of a wall. In this patent application such a wall will be generally referred to as a ‘compressed soil wall’.

[0003] The known method, however, has as a drawback that the stability and life span of the wall elements or the wall leaves to be desired. This is mainly caused by the often differing properties of the supplied soil and thus the resulting soil mixture used for constructing the wall.

[0004] The above especially holds when the wall is constructed as a delimitation for a water reservoir, such as a river or a ditch. The known walls can hardly be used for such purposes due to severe problems with mechanical stability and load carrying capability.

[0005] Due to their low ecological footprint, i.e. requiring comparatively small amounts of raw building materials and due to the wide availability of soil, the use of such walls for in particular the sheet piling of a water reservoir like a river or a ditch would be extremely advantageous. Nowadays, e.g. in The Netherlands, usually wood from countries such as Cameroon or Malaysia is imported to construct wooden sheet pilings. For creating such sheet pilings the Netherlands alone already consumes 1.6 million cubic metres for use therewith. This amounts to 3.2 million trees and a forest of approximately 80 square kilometres.

[0006] Another disadvantage of wooden sheet pilings is that their life span generally is only 30 years, mainly due to degradation by rot. Therefore, replacement thereof has to be carried out relatively frequently. For the Netherlands alone, the costs associated with replacement amount to 5-10 billion Euros.

[0007] It is therefore an object of the present invention to provide a method for creating a stabilized soil wall, wherein the stability, load carrying capability and life span of the wall is increased.

[0008] It is a further object of the invention to provide a method for creating a stabilized, such as compressed, soil wall, wherein the ecological footprint thereof is reduced.

Summary of the invention [0009] Hereto the method according to the invention comprises the steps of: - supplying soil to the location where a wall element that is to become part of the wall is to be created, - creating a compression space at the location where the wall element is to be created, - arranging an amount of soil in the compression space, - compressing the soil in the compression space to obtain the wall element, - arranging the wall element at the location where the wall is to be created and, if required, compressing subsequent wall elements and arranging them adjacent to the first wall element until the desired wall size is achieved.

[0010] The inventors have found that the above method increases the stability, load carrying capability and life span of the wall. Furthermore, the ecological footprint thereof is reduced due to the use of available soil, preferably local soil.

[0011] An embodiment relates to a method, wherein prior to the arranging of the amount of soil in the compression space to create the wall element, the soil is mixed, such as in a mixing device, to obtain a desired soil mixture, wherein the mixing comprises the addition of one or more desired additives based on the mechanical and chemical properties of the supplied soil. These additives may comprise stabilizing or binding additives. In this respect, it should be noted that usually the supplied soil is already pre-selected or pre-conditioned for use with a wall element. The above embodiment, however, advantageously seeks to be able to utilize virtually any type of supplied soil by analyzing the supplied soil and then adding additives as required (essentially ‘on the spot’). This allows a much broader range of soil types to be used, such as local soil, lowering in particular soil transportation costs and ecological footprint.

[0012] The additives may comprise reinforcing materials, such as fibres, for instance hemp or flax, or pozzolans, such as fly-ash.

[0013] An embodiment relates to a method, wherein during the mixing of the soil, such as in the mixing device, zeolite is added as one of the additives.

[0014] By adding zeolite to the soil mixture, the inventors have found that the stability, load carrying capacity and life span of the wall is significantly increased. Moreover, it has been found that zeolite can be used to effectively stabilize a wall created with a wide variety of supplied soil types, i.e. having very different soil properties.

[0015] Furthermore, zeolite is a raw material that can be found in nature as such.

Zeolite does not require further processing to exert its beneficial properties. Therefore, the ecological footprint of the wall is significantly reduced.

[0016] An embodiment relates to a method, wherein the supplied soil is excavated from the location where the wall is to be created or the direct vicinity thereof. This further reduces the ecological footprint of the wall, as the supplied soil does not have to be transported to the building site from a relatively far away location.

[0017] An embodiment relates to a method, wherein the wall forms the sheet piling of a water reservoir, such as a river or a ditch. The optional addition of zeolite effectively enables the wall to be used in an environment wherein permanent contact with water is unavoidable, in particular when the wall is used as a delimitation of a water reservoir, for instance a river or a ditch. As mentioned before, in nearly all situations this allows replacement of a wooden sheet piling by a compressed earth wall, allowing relatively large cost savings in countries where wooden pilings are commonplace. However, with wooden sheet pilings currently in use, it often happens that only the soil directly behind the sheet piling has become unstable (for example due to being partially flushed away). In such a case it is possible to use the sheet piling itself as a delimitation for the compression space. Subsequently, soil mixture is added to the unstable soil and subsequently compressed, using the method according to the invention, to obtain a newly stable ‘wall element’. The wooden sheet piling itself is thus not discarded, but is put to good use. The wall can also be used as a delimitation means within a water reservoir, to separate two bodies of water, such as with a fish trap.

[0018] It is also conceivable that the wall element or wall is used as a fence, for example to fence-off a plot of land. Otherwise it is conceivable that the wall elements are used to build an emergency wall, for example to counter flooding. When used with a fence, each wall element therein may have a width and/or height of 1,5 - 2,0 m, such as 1,8 m.

[0019] An embodiment relates to a method, wherein the mixing takes place in a mixing device arranged on a vessel floating on the water reservoir near the location where the wall is to be created. This allows the soil mixture to be produced as close as possible to the actual wall creation site.

[0020] An embodiment relates to a method, wherein, the excavation is carried out by an excavator arranged on the vessel. A significant advantage is that when local soil is to be used, e g. soil from the water reservoir or the edges thereof, the excavator can be conveniently used to excavate such soil and directly transfer the soil to the aforementioned mixing device for mixing.

[0021] An embodiment relates to a method, wherein during the mixing of the soil cement and/or lime, such as Portland cement, is added as one of the additives, being less than 50%, such as 5-10%, of the soil volume. Such (Portland) cement, especially in the aforementioned quantities, further stabilizes the wall or wall element.

[0022] In this respect it should be noted that the addition of so-called pozzolans nowadays is a worldwide trend. Many, but not all, pozzolans are environment-friendly additives that boost the mechanical properties of the used Portland cement. As a result thereof, less Portland cement and/or lime is needed, in common situations even up to 40%.

[0023] To increase the life span of a stabilized soil wall often fly ash is used as a pozzolan. Fly ash, however, is an artificial, i.e. man-made, material and therefore effectively causes the stabilized soil wall to have a significant ecological footprint. As found by the inventors, fly ash can be well-replaced by zeolite. Zeolite has been found to have terrific pozzolan properties and causes Portland cement to cure faster and/or to gain more strength. Due to the significant pozzolan properties of zeolite, even lower quantities of cement can be used to create a stable wall.

[0024] Another advantage of zeolite with respect to other pozzolans is that zeolite has good C02-absorbing properties. Therefore, a large part of C02-production caused by the production of Portland cement can be compensated for, thereby facilitating an even lower ecological footprint, even allowing the wall to be created in a ‘C02-neutral’ way.

[0025] Another advantage of the use of zeolite in the compressed soil wall is that smells and even pollution are absorbed and stabilized. Zeolite also causes the wall to have a higher resistance against intrusion by external substances or similar influences. This is of particular importance when the wall is used as sheet piling for delimiting a water reservoir and this especially holds when additional reinforcement or anchoring is used therewith.

[0026] Zeolite also prevents excessive dehydration of the wall, in particular when the wall is used as sheet piling. This property facilitates growth of plants and other vegetation on or near the wall. The roots of such vegetation protect the bank of the river, ditch or similar water reservoir, against erosion and increase the stability thereof. It is expected that in such conditions the lifespan of the compressed soil wall may possibly be increased to 100 years or even more.

[0027] An embodiment relates to a method, wherein the amount of zeolite to be added is 0,001-50%, such as 10-20%, preferably 15%, of the amount of added cement volume. The inventors have found this amount to give the compressed soil wall the best mix of properties with regards to mechanical stability, resistance against external influences and C02-absorption.

[0028] An embodiment relates to a method, wherein the supplied soil comprises polluted soil. As stated before, the optional zeolite will absorb and stabilize soil pollution allowing polluted soil to be used for building the compressed soil wall if desired.

[0029] An embodiment relates to an aforementioned method, wherein the zeolite is natural zeolite, preferably more than 95% natural zeolite, more preferably more than 97% natural zeolite, to obtain the lowest ecological footprint.

[0030] Another aspect of the invention relates to a method, wherein the compression space comprises a substantially vertical first plate or plate-like profile and a substantially vertical second plate, spaced-apart from the first plate, wherein the first and second plate extend along a substantially horizontal wall creation axis, and a substantially vertical third plate, arranged at a horizontal end of the first and second plates and extending substantially perpendicular to the first and second plates, wherein the third plate is moveable along the wall creation axis, wherein a soil compression space is delimited by the first, second and third plates, wherein, when the compression space is filled with the soil mixture, the third plate is moved along the wall creation axis to compress the soil mixture in the soil compression space. This allows relatively fast creation of a wall element or a block of a compressed soil wall.

[0031] An embodiment relates to a method, wherein the third plate is compressed against the soil mixture by a compression device attached to the horizontal ends of the first and second plates, wherein the compression device comprises a compression member moveable along the wall creation axis to compress the third plate against the soil mixture. Such a compression device enables the compression step to be carried out in a relatively short time period. Therein, effective use is made of the first and second plates to exert counter pressure.

[0032] An embodiment relates to a method, wherein the first, the second and the third plate are compressed against the soil mixture. Thus, the wall element is compressed from several sides to obtain more even compression.

[0033] An embodiment relates to a method, wherein the compression of soil is carried out with vibrations. Thus, an even more densely compacted wall can be obtained.

[0034] An embodiment relates to a method, wherein, when a first wall element of compressed soil is created, the first, second and third plate are shifted along the wall creation axis to a location next to the first wall element to create one or more subsequent wall elements of compressed soil until a desired wall size is achieved. Such a method allows the creation of a continuous compressed soil wall while minimizing equipment use, in particular use of compression space.

[0035] An embodiment relates to a method, wherein, for the one or more subsequent wall elements, the soil compression space is delimited by the first, second and third plate, and a side surface of a previous wall element of compressed soil, such as a side surface of the first wall element. This allows the building of a continuous wall along the wall creation axis in a fast manner. The skilled person will realize that for the first wall element or block an additional piece of vertical compression space will be needed, opposing the third plate and extending parallel thereto, to properly delimit the compression space.

[0036] Another aspect of the invention relates to a stabilized soil wall, comprising one or more wall elements of compressed soil, wherein the compressed soil wall is created with the aforementioned method.

[0037] An embodiment relates to a stabilized soil wall, wherein at least one wall element comprises a soil mixture containing zeolite.

[0038] An embodiment relates to an aforementioned stabilized soil wall, wherein one of the wall elements comprises a soil mixture containing soil that has been excavated from the location where the wall has been created or the direct vicinity thereof.

[0039] An embodiment relates to an aforementioned stabilized soil wall, wherein the wall forms the sheet piling of a water reservoir, such as a river or a ditch.

[0040] An embodiment relates to an aforementioned stabilized soil wall, wherein one of the wall elements comprises a soil mixture containing less than 50%, such as 5-10% cement, in relation to the soil volume.

[0041] An embodiment relates to an aforementioned stabilized soil wall, wherein one of the wall elements comprises a soil mixture containing an amount of zeolite of 0,001-50%, such as 10-20%, of the amount of soil volume in that wall element.

[0042] Another aspect of the invention relates to a compression device for use in the method, comprising a housing with two attachment elements, wherein each attachment element is suitable for attachment to the horizontal end of either the first or the second plate, and a compression member arranged between the attachment elements. Such a compression device can be quickly attached and detached from the horizontal ends of the first and second plates.

Brief description of the drawings [0043] Embodiments of a method for creating a stabilized or compressed soil wall element or wall, and a stabilized soil wall according to the invention, will by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings: [0044] Figure 1 shows a perspective view of an exemplary embodiment of the method according to the invention and a stabilized soil wall created therewith.

Detailed description of the invention [0045] Figure 1 shows a perspective view of an exemplary embodiment of the method according to the invention. Figure 1 more specifically shows a method for creating a stabilized, such as compressed, soil wall 1 according to the invention, comprising the steps of supplying soil to the location where the wall 1 is to be created, such as the bank of a river or a ditch. Subsequently a compression space 2 is created at the location where the wall 1 (or more generally, a wall element for use in a wall) is to be created, for example by using formwork. Then the soil is preferably mixed in a mixing device 3 with one or more desired additives 4 to obtain a desired soil mixture 5. Thereafter, an amount of soil mixture 5 is arranged in the compression space 2. To provide the wall 1 with the necessary' mechanical strength, the first wall element 7 of soil mixture 5 is then compressed in the compression space 2, for instance by using compression, ramming or vibrations. Subsequent wall elements 6, 8 of soil mixture 5 may be added and compressed in the same way adjacent to the first wall element 7 until the desired wall size is achieved. Optionally, during the mixing of the soil in the mixing device 3, zeolite is added as one of the additives.

[0046] As shown in figure 1, the supplied soil is preferably excavated from the location where the wall 1 is to be created or the direct vicinity thereof, such as the bank of a water reservoir 10. The soil can be polluted to a certain degree without hindering the carrying out of the invention. By contrast, the additives to be added can be adapted both in type as well as dosage to take the pollution of the soil into account.

The wall 1 as shown forms the sheet piling 9 of the water reservoir 10, such as a river or a ditch. However, the wall can also be used for other purposes, such as for creating the delimitation of an area, such as a garden, or a road.

[0047] In the example as shown, the mixing takes place in a mixing device 3 arranged on a vessel 11 floating on the water reservoir 10 near the location where the wall 1 is to be created. As can be seen in figure 1, the excavation is carried out advantageously by an excavator 12 arranged on the vessel 11.

[0048] During the mixing of the soil in the mixing device 3 5-10% cement and/or lime, such as Portland cement, is added as one of the additives 4. Preferably, the amount of zeolite to be added is 10-20% of the amount of added (Portland) cement and/or lime to achieve optimal results. Furthermore, the zeolite preferably contains close to 100% natural zeolite.

[0049] In the exemplary embodiment of the method as shown in figure 1, the compression space 2 comprises a substantially vertical first plate 13 and a substantially vertical second plate 14, spaced-apart from the first plate 13, such as over a distance of 0.1 - 0.5 m. The first 13 and second plate 14 extend along a substantially horizontal wall creation axis X. A substantially vertical third plate 15 is arranged at a horizontal end of the first 13 and second plates 14 and extends substantially perpendicular to the first 13 and second 14 plates. The third plate 14 is moveable along the wall creation axis X. A soil compression space 16 is delimited by the first 13, second 14 and third 15 plates. When the compression space 16 is filled with the soil mixture 5, the third plate 15 is moved along the wall creation axis X to compress the soil mixture 5 in the soil compression space 16. The excavator 12 can be conveniently used to compress the top surface of the soil mixture 5. The plates 13, 14, 15 can be made of any suitable material, such as concrete, wood or metal.

[0050] Therein, the third plate 15 is compressed against the soil mixture 5 by a compression device 17 attached to the horizontal ends of the first 13 and second 14 plates. The compression device 17 comprises a compression member 20, such as a piston, moveable along the wall creation axis X to compress the third plate 15 against the soil mixture 5. The compression device 17 basically comprises a main body or a housing with two attachment elements 19, wherein each attachment element 19 is suitable for attachment to the horizontal end of either the first 13 or the second plate 14. The attachment elements 19 may comprise a suction device, mechanical clamps, et cetera. The compression member 20 is preferably arranged between the attachment elements 19 for symmetric power exertion on the third plate 15.

[0051] When a first wall element 6, 7 of compressed soil is created with the method, the first 13, second 14 and third plate 15 can be conveniently shifted along the wall creation axis X to a location next to the first wall element 6, 7 to create one or more subsequent wall elements 6, 8 of compressed soil until a desired wall size, in particular a desired length along the wall creation axis X, is achieved. After the shifting of the plates 13, 14, 15 along the wall creation axis X, the soil compression space 16 can be delimited by a side surface 18 of a previous wall element 6, 7 of compressed soil, such as a side surface of the first wall element 6, 7, i.e. the surface 18 extending perpendicular to the wall creation axis X.

[0052] Thus, the invention has been described by reference to the embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.

Reference numerals 1. Stabilized soil wall 2. Compression space 3. Mixing device 4. Additives 5. Soil mixture 6. Wall element 7. First wall element of wall 8. Subsequent wall element of wall 9. Sheet piling 10. Water reservoir 11. Vessel 12. Excavator 13. First plate 14. Second plate 15. Third plate 16. Soil compression space 17. Compression device 18. Side surface of previous wall element 19. Attachment element of compression device 20. Compression member of compression device X. Wall creation axis

Claims (25)

Method for creating a stabilized soil wall (1), comprising the steps of: - supplying soil to the location where a wall element to be part of the wall is to be created, - creating a compression space ( 2) at the location where the wall element is to be created, - applying a quantity of soil in the compression space, - compressing the soil in the compression space to obtain the wall element (6, 7), - applying the wall element on the location where the wall is to be created and, if required, the compression of successive wall elements (6, 8) and the fitting of these wall elements adjacent to the first wall element until the desired wall size is reached. A method according to claim 1, wherein prior to applying the amount of soil in the compression space to create the wall element (6, 7), the soil is mixed, such as in a mixing device (3), to a desired soil mixture (5) obtainable, wherein the mixing comprises adding one or more desired additives (4) based on the mechanical and chemical properties of the soil supplied. The method of claim 2, wherein the additives comprise reinforcing materials, such as fibers, for example hemp or flax, or puzzolans, such as fly ash. A method according to claim 2 or 3, wherein during mixing of the soil, such as in the mixing device, zeolite is added as one of the additives. The method according to any of claims 1-4, wherein the supplied soil is excavated from the location where the wall is to be created or its immediate proximity. Method according to one of the preceding claims, wherein the wall forms the covering (9) of a water reservoir (10), such as a river or a ditch. The method of claim 5, wherein the mixing takes place in a mixing device mounted on a vessel (11) floating on the water reservoir near the location where the wall is to be created. A method according to claim 6 or 7, wherein, when dependent on claim 5, the excavation is performed by an excavator (12) mounted on the vessel. A method according to any one of the preceding claims, wherein during mixing of the soil, cement and / or lime is added as one of the additives, being less than 50%, such as 5-10%, of the soil volume. A method according to claim 9, wherein the amount of zeolite to be supplied is 0.001-50%, such as 10-20%, preferably 15%, of the amount of added cement and / or lime volume. A method according to any one of the preceding claims, wherein the supplied soil comprises contaminated soil. The method of any one of claims 4 to 11, wherein the zeolite is natural zeolite. A method according to any one of the preceding claims, wherein the compression space (2) comprises a substantially vertical first plate (13) or plate-like shape and a substantially vertical second plate (14) spaced from the first plate, the first and second second plates extend along a substantially horizontal wall creation axis (X), and a substantially vertical third plate (15) disposed at a horizontal end of the first and second plates and extending substantially perpendicular to the first and second plates, the third plate is movable along the wall creation axis, wherein a compression space (16) is delimited by the first, second and third plates, wherein, when the compression space is filled with the soil mixture (5), the third plate is moved along the wall creation axis around the soil mixture in the compressing compression space for soil. The method of claim 13, wherein the third plate is compressed against the soil mix by a compression device (17) attached to the horizontal ends of the first and second plates, the compression device comprising a compression device (20) movable along the wall creation axis compressing the third plate against the soil mixture. The method of claim 14, wherein the first, the second, and the third plate are compressed against the soil mix. A method according to any one of the preceding claims, wherein the compression of soil is carried out using vibrations. A method according to any of claims 13-16, wherein, when a first wall element of compressed soil is created with the method according to claim 13 or 14, the first, second and third plates are shifted along the wall creation axis to a location adjacent to the first wall element to create one or more consecutive wall elements of compressed soil until a desired wall size is reached. The method of claim 17, wherein, for the one or more consecutive wall elements, the soil compression space is bounded by the first, second and third plates, and a side surface (18) of a previous wall element of compressed soil, such as a side surface of the first wall element. A stabilized soil wall (1), comprising: one or more wall elements (6, 7, 8) of compressed soil created by the method according to any of claims 1-18. The stabilized soil wall (1) according to claim 19, wherein at least one wall element contains a soil mixture with zeolite. The stabilized soil wall (1) according to any of claims 18-20, wherein one of the wall elements comprises a soil mixture with soil excavated from the location where the wall was created or its immediate proximity. A stabilized soil wall (1) according to any of claims 18-21, wherein the wall forms the embankment (9) of a water reservoir (10), such as a river or a ditch. A stabilized soil wall (1) according to any of claims 18-22, wherein one of the wall elements comprises a soil mixture with less than 50%, such as 5-10% cement and / or lime, relative to the soil volume. The stabilized soil wall (1) according to any of claims 18-23, wherein one of the wall elements comprises a soil mixture with an amount of zeolite of 0.001-50%, such as 10-20%, of the amount of soil volume in that wall element. A compression device (17) for use in a method according to any of claims 13-18, comprising a housing with two mounting elements (19), each mounting element being suitable for mounting on the horizontal end of the first or the second plate, and a compression body (20) disposed between the fastening elements.