Patent Grant
8790043
1. Technical Field
The invention relates to a foundation for structures.
2. Prior Art
Structures which are to be erected on soft subsoil can be supported and secured against settlement movements by pile foundations. A load distribution layer is as a rule arranged between the piles (below) and the structures (above) so that the loads originating from the structure can thus be directed into the piles. In order to achieve this object, the load distribution layer must have a specific thickness and be made from a specific material. Load distribution layers of sand are known from the prior art.
The object of the present invention is to modify the load distribution layer in such a way that the foundation as a whole can be constructed in a more cost-effective and stable fashion and/or more quickly.
The foundation according to the invention is a foundation for structures, comprising a combination of pile-like support elements (11); and a load distribution layer (12) which is arranged above said support elements, the load distribution layer (12) having an incorporated three-dimensional matrix-like structure or honeycomb structure. According to these features, the foundation for structures has a combination of pile-like support elements and a load distribution layer arranged above said support elements, a three-dimensional matrix-like structure being incorporated into the load distribution layer. The load distribution layer is here preferably generally a combination of a pourable material, for example sand, with an incorporated honeycomb structure. The latter is intended to prevent or limit in particular transverse movements of the pourable material, that is lateral yielding of the pourable material owing to the static loads of the structures. Advantageously, the pourable material in the load distribution layer has the same height as the honeycomb structure. Alternative arrangements are possible.
It is provided within the scope of the invention that the support elements stand on or in a load-bearing subsoil and extend through an inadequately load-bearing layer as far as the load distribution layer.
A further concept of the invention is that the honeycomb structure has predominantly, in particular exclusively upright walls. “Upright” here means an orientation that is also parallel to the main direction in which the support elements extend. In this way, transverse movements of the pourable material in the load distribution layer are effectively prevented.
In a further concept of the invention, it is provided that the honeycomb structure predominantly, in particular exclusively, has walls which are oriented perpendicularly to the extension of the load distribution layer. Upright walls of the honeycomb structure thus result in a horizontally oriented load distribution layer.
The honeycomb structure is preferably designed so that it is open at the top—in the direction of the structure—and at the bottom—in the direction of the support elements. Water absorption and permeability are thereby optimized.
A further concept of the invention is that a compensation layer, preferably of sand, is provided beneath the load distribution layer and the support elements extend into it. The compensation layer serves to adjust the height of the support elements. The upper end faces of the latter end at approximately the same height. In most cases, exactly identical heights are not possible because of the design. The differences can be compensated by the compensation layer. The thickness of the compensation layer is preferably 1 cm to 10 cm. The thicker the compensation layer, the greater too its additional load-distributing effect. Ideally, no compensation layer is provided.
A further concept of the invention is that the honeycomb structure has cavities with a width of 25 cm or greater. The width should here be measured in a direction parallel to the extension of the load distribution layer. If possible, the cavities all have approximately the same size. Accordingly, the cavities do not have a circular cross section. The specified width preferably relates to the smallest width within a cavity. A larger width can also result, depending on the direction of measurement.
According to the invention, the honeycomb structure can have walls and/or cavities with a height of 5 cm to 15 cm. The height then preferably extends in a direction perpendicular to the extension of the load distribution layer. Surprisingly, experiments have shown that diameters or rather walls with a height from just 5 cm to 15 cm suffice for specific applications even in the case of larger cavities of 25 cm. As a result, the load distribution layer as a whole can be designed to be relatively thin. Accordingly, the amount of material used is reduced. At the same time, construction time is shortened.
In a further concept of the invention, it is provided that the honeycomb structure has perforated walls with a perforation of 0% to 40% of the total wall surface. The perforations, for example in the form of bores or other openings which are arranged the same distance apart from one another, make the walls permeable to water and fine grains. 0% corresponds to a design with no perforations.
According to the invention, the honeycomb structure can be formed from corrugated strips, wherein the strips are connected to one another in the region of corrugation peaks and corrugation troughs. When the walls have an upright arrangement, the corrugation peaks and troughs are not situated at the top and bottom but laterally offset relative to each other. Large-surface honeycomb structures can be formed quickly and simply with the described strips.
A further concept of the invention is that the honeycomb structure has adjacent cells or cavities with a surface area of 400 cm2 or greater. The surface area is here preferably measured parallel to the extension of the load distribution layer.
According to the invention, the honeycomb structure can have adjacent cells with walls which are connected to walls of other and/or the same cells, wherein force-fitting connections between the walls are designed for a loading of preferably approximately 1 kN in each case. Connections which can be loaded in this way effectively prevent the interconnected walls from being separated or the honeycomb structure as a whole from failing, and do so for most applications.
In a further concept of the invention, it is provided that the honeycomb structure has walls made of HDPE or other polymeric materials. HDPE (high density polyethylene) is a durable material which can withstand high loads and, depending on the thickness, is flexible. The walls can also be formed from nonwoven fabrics.
The honeycomb structure has in particular walls between 1 mm and 3 mm thick. Walls with a thickness between 1 mm and 2 mm are preferably provided. The design of the walls tends to be thicker, the more perforations there are provided.
The support elements are advantageously columns with a 40 cm to 80 cm diameter and can, for example, be cast from concrete. A grid arrangement of the support elements is preferred, with a spacing of 1.50 m to 3.50 m from one another.
In a further concept of the invention, it is provided that a nonwoven fabric is provided on or in the compensation layer. The nonwoven fabric is preferably a water-permeable textile layer, by means of which, for example, a mingling of material above and below the nonwoven fabric is prevented. A nonwoven fabric is advantageously arranged directly beneath the load distribution layer.
A further concept of the invention is that two or more load distribution layers are arranged above one another, with spacings of preferably 0 cm to 50 cm, wherein the support elements can reach as far as the lower load distribution layer. Experiments have shown that two load distribution layers one above the other can achieve better results than a single load distribution layer with the same total thickness as the two load distribution layers. This effect can be explained by the compacting of the material within the load distribution layer. The material can be better compacted in two flat load distribution layers one after the other than in a single high load distribution layer. It is also possible to arrange more than two load distribution layers one above the other with or without gaps.
In a further concept of the invention, it is provided that compensation layers, preferably 0 cm to 50 cm thick, are in each case arranged between the load distribution layers. One compensation layer is advantageously situated in each case between two load distribution layers.
In a further concept of the invention, it is provided that one or more compensation layers have a changing thickness profile. A lower compensation layer between a load distribution layer and support elements compensates tolerances when the support elements settle. Other adjustments can be made to the required precise height of the foundation by means of a changing thickness of a further compensation layer between two load distribution layers.
A nonwoven fabric, which may optionally be present, is advantageously arranged at least below the lowest load distribution layer in the case of multiple load distribution layers. Nonwoven fabrics can, however, also be provided below further or below all load distribution layers.
It is within the scope of the invention to use the foundation with one or more of the abovementioned features for
Other features of the invention are apparent from the description and from the claims. Advantageous exemplary embodiments of the invention are explained in more detail below with reference to drawings, in which:
It is intended for a structure, not shown, to be erected on a non load-bearing subsoil, namely a soft layer 10. In order to be able to erect the structure securely, a special foundation is provided. The latter here has column-like support elements 11 and a load distribution layer 12 arranged above said support elements 11.
The support elements 11 are here designed as concrete columns which stand upright and extend through the whole soft layer 10 as far as a load-bearing subsoil 13 below the soft layer 10. Upper ends of the support elements 11 project into a compensation layer 14 of compacted sand. Any differences in height which exist between the support elements are compensated by the compensation layer 14. At the same time, the compensation layer 14 can contribute to the distribution of loads.
The compensation layer 14 is covered by a water-permeable textile layer, a nonwoven fabric 15. Arranged directly on top of the nonwoven fabric 15 is the load distribution layer 12 on which, for example, a frost protection layer and a road surface (not shown) can lie, or an embankment structure.
The load distribution layer 12 preferably has an incorporated three-dimensional honeycomb structure. The honeycomb structure is filled with compacted sand. Loads resting on the load distribution layer 12 are directed through the sand and the honeycomb structure into the support elements 11.
The three-dimensional honeycomb structure of the load distribution layer 12 consists of plastic strips 16 arranged in a meandering shape and with upright walls. The meandering shape creates the impression for each plastic strip 16 of an almost sinusoidal profile. Mutually adjacent plastic strips 16 are—in terms of a sine curve—offset by 180° to one another so that cavities 17 or honeycomb cells which are open at the top and bottom result.
For installing the honeycomb structure on the construction site, multiple plastic strips 16 are connected to one another in advance to form a honeycomb unit 18. On the construction site, multiple honeycomb units 18 are then connected to one another in force-fitting fashion in the region of outer arcs 19 and projecting fins 20. To achieve this, connecting means (not shown) are used, for example of a mechanical type or by adhesive bonding or welding. The fins 20 are formed by interconnected ends of adjacent plastic strips 16.
To simplify matters, in
The height of the honeycomb structure, and accordingly of the perforated plastic strips 16 and the load distribution layer 12 too, is approximately 5 cm to 15 cm with a width of the individual cavities 17 or honeycomb cells of more than 25 cm and/or a surface area covered by the cavities 17 of more than 400 cm2 in each case. The compensation layer 14 should be as thin as possible and has a thickness of approximately 1 cm to 20 cm. Ideally, no compensation layer is provided.
The support elements 11 are here designed as concrete columns with a diameter of approximately 40 cm to 80 cm. The individual columns in the grid here have a spacing of approximately 2 m to 3.50 m.
The connections between the adjacent or consecutive plastic strips 16 are designed for a tensile force of approximately 1 kN. HDPE with a wall thickness of 1 mm to 2 mm is preferably used as the material.
The support elements 11 reach as far as the lower compensation layer 14 or extend into the latter, as also shown in
The compensation layers 14 are here designed in the longitudinal extension of the structure—arrow 21—with a uniform thickness. However, different thicknesses are also possible in the direction of extension, in particular to compensate different heights between the soft layer 10, on the one hand, see
The use of multiple superposed load distribution layers 12, 112, 212 is particularly advantageous as a greater compaction of the material can be obtained within each load distribution layer than for a single relatively high load distribution layer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 007 931 | Feb 2009 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/004511 | 6/23/2009 | WO | 00 | 9/30/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/088929 | 8/12/2010 | WO | A |
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| Canadian Intellectual Property Office, Examination Report (for related Canadian patent application No. 2751809) (Jan. 24, 2013). |
| Number | Date | Country | |
|---|---|---|---|
| 20120020743 A1 | Jan 2012 | US |
