DE4440787A1 - Prefabricated support for use on weak or unstable ground - Google Patents

Abstract

The support has fibrous reinforcing material (10) on at least its underside. It usually takes the form of a grid, and can withstand thrust and tension forces.The grid may have recesses, each in the shape of a square, rectangle, circle, rhombus or polygon, and an upper fabric material may be applied to increase its stiffness. It may be made from steel-reinforced concrete, steel, plastic, concrete, or fibre-reinforced concrete, and preferably from a mixture of airborne-ash. The edges of the grid may also be tapered conically, and the transmission and distribution of loads may be performed by elements which are non-corrosive.

Description

Earthworks as the underground of streets, paths, squares and lanes for everyone Species require very careful planning to avoid later damage and execution. In the case of new plants and conversions, this is done according to the knowledge of modern earthwork mechanics.

The planners endeavor to do this by using modern machines and Control methods to achieve uniform compaction and stability everywhere.

If, however, it often causes damage and deformation of the earth's body comes, there are various reasons for this. Often is next to one irregular and poorly compacted earth material also the penetration of Water and insufficient frost resistance as well as insufficient Load distribution among the respective points of attack the reason for the occurred Deformations.

In order to increase the load-bearing capacity on poor soils, the existing one is often used Soil through layers with greater uniformity and better resilience replaced. This causes high costs and extensive material transports.

For some time have been used to increase the load-bearing capacity of earthworks and the Surfaces of roads and all kinds of geo-textile tracks and also flat plastic grille related. These materials have proven their worth, but are taking off it is accepted that in the case of excessive loads, failure of the thin ones Plastic webs or grids occur due to the low material thickness. A better load distribution can only be found by increasing the shear strength in the small dimensions instead, but better interlocking of the earth masses among themselves.

Geotextiles and plastic grids are excellent because of their high elasticity suitable for transmitting and absorbing tensile forces. First the reshaping of the a tensile force acting in sub-forces allows the tensile strength of the Geotextiles come into effect. The mesh knots of a fabric that is in embedded in a solid to plastic medium, anchor it more or less tight in the enveloping body.

When pressure forces occur at right angles to the bearing direction, it depends crucially depending on the embedding, the strength of the fabric and its elasticity, how big the initial deformations are transformed into tensile forces until the compressive forces are converted and prevent further deformation. These minor Elastic deformations often become permanent deformations over time which damage the building.  

A more elegant way to improve load capacity is to make sure that water and frost do not change the earth's body (P. 44 03 978.6). If this is reached and the surface is always exposed to the same conditions, then can improve the load-bearing capacity even better by better load distribution will.

The invention described below describes a system with which it is based simple way is the load-bearing capacity and stability of foundations of all kinds, but especially of earthworks, roads and lanes.

It is important to choose the right construction system Reduce permanent deformations or even at low load-bearing floors impossible to make and at the same time the usual soil exchange and the associated mass transports are largely unnecessary.

For this purpose, a prefabricated grate ( Fig. 1, 2) was developed which, when loaded, distributes the load given to it by its own stiffness over a larger area and thus automatically leads to a reduction in the stresses in the supporting body and the base via a better load distribution.

So that the grate can also have a full effect, it is placed on a close-knit, rot-proof fabric ( 10 ) after the formation of the formation, or a fabric that extends over the recesses was immediately inserted during the manufacture of the grate. When loaded from above, the grate is pressed into the ground. The floor to be displaced tries to escape into the open spaces of the grate. The close-meshed fabric prevents it from penetrating into the cavities between the ribs.

Tensile stresses develop in the fabric, which act on the ribs ( 20 ) of the grate in the neighboring fields and thus bring about a better load distribution from the ribs and which counter the sinking of the grate. However, since the grate also has a high degree of inherent rigidity, in contrast to textile reinforcement, it also transfers the vertical load acting on it via longitudinal ribs ( 20 ) and transverse ribs ( 21 ) and the fabric 10 located below to a larger area.

The better load distribution reduces the surface pressure. If the Surface pressure is reduced and the subsurface prevents the ingress of frost and Water is protected, so can floors with low load-bearing capacity Transfer large loads. Extensive material transport for excavation and installation material can then be significantly reduced.

If, in special cases, an even better load distribution from above is required, then another fabric ( 11 ) must be placed over the grate, which, when loaded from above, transfers the vertical load to the ribs of the grate via tensile stresses and thus distributes the load even better ( Fig. 5).

The material that has entered the space between the ribs of the grate increases the shear and displacement resistance of the underlying or material lying above with forces acting perpendicular to the grate plane.

The closer the grate is to the load application level, the better its Load distribution.

The distance between the ribs, the thickness of the grate, the shape of the openings, whether rectangular, square ( Fig. 1) or round ( Fig. 2), the thickness of the underlying fabric, mesh spacing and material, depend on the individual cases and requirements from.

The load distribution gratings are made from reinforced concrete, plastic, recycled plastic or preferably from fly ash cement mixtures (FAZ). Gratings made from fly ash cement mixtures are provided with inlaid textile fabrics ( 12 , 13 ) on both sides during production to increase the tensile bending strength. On the front and long sides, the joints are formed according to ( Fig. 5) and held together by a bolt connection with corrosion-protected steel tabs on both sides, so that they cannot move against each other even under heavy loads.

The structure above the grate and any fabric on top usually corresponds to the known earthworks and road construction methods.

However, if you proceed according to P application 44 03 978.6, care must be taken that Surface and capillary water cannot penetrate into the construction and also by installing thermal insulation to freeze upwards is pushed.

If the entire construction is more frost-resistant, the usual ones can be used Significantly reduce layer thicknesses and the whole structure is essential to manufacture more economically.

Instead of the grate construction, mats made of FAZ mixtures with fabric inserts on both sides ( Fig. 12) can be installed to improve the load distribution to increase the bending strength. However, a thin sealing layer then arises, in which careful attention must be paid to the discharge of the impinging water.

Another area of application for the gratings is in the construction of new and widening existing dams ( Fig. 3, Fig. 14). Since the system, consisting of the rot-proof textile fabric ( 10 ) on the underside, the grate ( 1 ) and possibly an rot-proof fabric ( 11 ) on the top, not only results in a much better load distribution, but also significantly improves the shear strength of the floor , slope slopes can be made much steeper than usual. Less footprint is required for dams. Expensive supporting structures can be omitted or only need to be constructed with a minimum height. In such cases, a grate ( Fig. 6) must be set up on the outside of the dam to protect the embankment from erosion.

Due to their great flexural strength, grids and load distribution mats made from FAZ mixtures (fly ash mixtures) with fabric reinforcement on both sides can be installed for the economic load distribution of strips and individual foundations ( Fig. 8).

Several elements can be overlaid without interrupting work. After inserting shear bars and immediately pouring the honeycomb with grout ( 5 ), you can continue working on the rising masonry. They can also be used as formwork for rising walls, which are filled with grouting concrete after stacking ( Fig. 8).

Gratings and load distribution mats are also suitable as a cleanliness layer on construction sites and save working time and work space ( Fig. 8, 4), ( Fig. 12) and Fig. 15.

Gratings with underside fabric and load distribution mats are suitable for the construction of reusable construction roads. You will be on the leveled surface hung up and after completion of the work again for a new use purpose added.

They are very suitable for securing slopes. In the factory, they can be manufactured in such a way that they are laid over edges and in grooves and can also be used as channels ( Fig. 10, 11 and 17).

During production, the inserted fabric is not cast around the potting compound in the areas of the kinks, as a result of which the individual legs ( 30 ) can be adapted to the respective angles on the construction site. After installation, the kink area is cast with locally hardening potting material ( 32 ).

Another area of application for the gratings described with external fabric back tensioning is the economical installation of trenches and pits ( FIGS. 7, 15 and 16).

For this purpose they are excavated or milled side by side Trenches made and clamped in the ground, possibly also stiffened.

The fabric reinforcement on both sides ( 12 , 13 ) allows the absorption of relatively high bending stresses. After completion of the work, the individual elements are removed and reused several times.

Another extensive area of application for gratings and load distribution mats is Road construction. In the case of bituminous ceilings, this gives way under standing load Overcoat and binder course over time. Bituminous roads behave like elastic binders according to their binder Properties change with the outside temperature.

In front of traffic lights you can often see some time after the completion of the  Bituminous pavement gradually find gutters that form after a cause further damage to the road.

Deformations occur in the road, which occur less under the moving traffic than under the stationary traffic. If gratings ( FIG. 9) are arranged under or in the bitumen support or binder layer, the bitumen layer interlocks in the free spaces present between the ribs. The stronger shear resistance prevents elastic deformation of the base and top layers.

The road surface including the base course is subject to less wear Signs of wear and the more favorable load distribution leaves a weaker one Construction too. The economy of the road body is improved.

The following advantages result from the invention:

• 1. Low-stress floors can be better and more evenly distributed effect of the grates can be measured with higher loads.
• 2. The better load distribution often makes the exchange of soil layers unnecessary.
• 3. The extensive elimination of the soil exchange leaves necessary construction work become more economical.
• 4. The elimination of soil exchange shortens the construction time.
• 5. Base layers made of hydraulically and bituminous bound material can be dimensioned weaker ( Fig. 9).
• 6. Newly erected or widened earthworks can be provided with a steeper slope ( Fig. 6, Fig. 14).
• 7. The shear strength of the earth to be built is increased considerably.
• 8. On construction roads, immediately after leveling and covering the existing one Ground the support body or support plates are placed. For assembly and disassembly less material is required.
• 9. By increasing the internal shear resistance, deformations bituminous surfaces in road construction are delayed or prevented.
• 10. When used as prefabricated foundations ( Fig. 8) or part of foundations and as a formwork, the required work space and thus the excavation and construction time is reduced.
• 11. Support mats as a finished layer of cleanliness ( Fig. 15) and as a protective layer allow immediate further work.
• 12. Simple and economical shoring of trenches and pits ( Fig. 7, Fig. 15, Fig. 16).
• 13. Quick installation and quick creation of drainage channels using prefabricated elements that can be adapted to any inclination ( Fig. 10).
• 14. Simple embankment protection for all kinds of embankments, also used in hydraulic engineering for bank reinforcement and securing dunes by placing prefabricated elements that are also suitable for embankment edges ( Fig. 3, Fig. 13, Fig. 17).

Claims (14)

1. Prefabricated support body for better load distribution, to increase the load-bearing capacity of poor substrates, to improve the stability of earthworks and roadways of all kinds, characterized in that reinforcing fabrics made of fibers of different types are inserted or underlaid at least on its underside and not only compressive forces but also Can absorb bending tensile forces and in most cases is designed like a grate ( 1 ). 2. Prefabricated support body according to claim 1, characterized in that it is designed like a grating and that the honeycomb-shaped recesses in the lattice construction are rectangular, square ( Fig. 1), round ( Fig. 2), diamond-shaped or polygonal and that at Full cross-section on both outer sides of fiber fabric ( 12 , 13 ) are inserted to increase the bending strength. 3. Prefabricated support body according to claim 1, characterized in that it is made of Reinforced concrete, steel, plastic, concrete, fiber concrete, but preferably made of FAZ Mixtures (fly ash mixtures) with fiber admixtures is produced. Size and shape of the recesses as well as the strength of the body will be chosen according to the static requirements. 4. Prefabricated support body according to claim 1, characterized in that the edges can be conical and that the load transmission and distribution takes place via corrosion-resistant connecting elements ( Fig. 4). 5. Prefabricated support body according to claim 1, characterized in that at Load from above the fabric located on the underside of the support body made of non-rotting material, about the tensile stresses that arise Penetration of the support body counteracts. The load from above becomes evenly distributed over a larger area. Peak loads are in mined an area. This property helps excessive exchange to avoid soil masses. 6. Prefabricated support body according to claim 1, characterized in that the rot-proof fabric located on the underside of the support body grate is pressed into the honeycomb-shaped recesses when loaded from above ( FIG. 1, FIG. 3, FIG. 6) and the shear strength of the normal Soil or the fill increased and at the same time considerably increased the internal friction angle. 7. Prefabricated support body according to claim 1, characterized in that the honeycomb-shaped body ( Fig. 9) inserted in a bitumen support or binder layer ( Fig. 9) in addition to a better load distribution also increases the internal shear resistance of the bitumen mass to be introduced and the evasion of the covering material either prevents or very difficult. 8. Prefabricated support body according to claim 1, characterized in that at  Use as a construction road on cohesive terrain due to the particularly good Load distribution of the existing soil is not removed, but only leveled must be and that the support body can be used several times. 9. Prefabricated support body according to claim 1, characterized in that it can be used not only as a transmitter of vertical loads, but also for the transmission of horizontal loads in the excavation and that in these cases the back fabric layer the pressure loads from the earth via tensile stresses on the Ribs of the grid-shaped support body transfers ( Fig. 7, Fig. 15, Fig. 16). 10. Prefabricated support body according to claim 1, characterized in that it can be used to secure embankments of any kind, also in hydraulic engineering ( Fig. 13), and that the water pressing out of the earth at any time by the on the bottom or back with rot-proof Tissue-covered honeycomb-shaped recesses of the grate can emerge on the surfaces and thus an enrichment of the earth's body with water and a reduction in the internal friction is avoided. 11. Prefabricated support body according to claim 1, characterized in that it for slope stabilization and construction of grooves (Fig. 10 and Fig. 17) consists of several, but at least consists of two partial bodies, by rot-proof, but not infused fabric plies (12, 13 ) are connected to each other and are put together at the desired angle at the installation site. By potting the open joint with the fabric inserts anchored on both sides in the support body, a tensile-resistant, rot-proof connection of the individual parts is subsequently created. 12. Prefabricated support body according to claim 1, characterized in that several partial bodies with honeycomb-shaped recesses to create one Foundation block or masonry are superimposed and that the honeycomb-shaped recesses are poured with grouting concrete. For Shear stresses cannot be absorbed into steel bars yet insert cast honeycomb. After casting a honeycomb block, you can be continued immediately. A formwork of the foundation body or the Wall is not necessary. 13. Prefabricated support body according to claim 1, characterized in that it is installed on construction sites with honeycomb-shaped recesses or as a full cross-section with lower and upper fabric reinforcement as a strip foundation ( Fig. 8, 4). 14. Prefabricated support body according to claim 1, characterized in that it as a full cross-section ( Fig. 15) with lower and upper fabric reinforcement ( 12 , 13 ), as a cleanliness layer for building structures and as an upper or vertical protective layer protective layer for seals in deep, bridge and Building construction is installed.