Patent Application
20240417945
The invention relates to a method for forming a support wall in the ground from a soil mortar which is prepared in the ground by mixing soil material and a cement suspension, wherein vertically directed support beams comprising a structural steel are set into the soil mortar in the ground prior to curing, and after curing, soil material is removed along an upper support wall section on at least one side of the support wall, while a lower support wall section continues to be surrounded by soil on both sides, according to the preamble of claim 1.
The invention further relates to a support wall in the ground made of a soil mortar, wherein the soil mortar in the ground is prepared by mixing soil material and a cement suspension and is cured in the ground to the support wall, vertically directed support beams, which comprise a structural steel, are set into the soil mortar in the ground prior to curing, and after curing, by removal of soil material, the support wall is exposed on at least one side along an upper support wall section, while a lower support wall section continues to be surrounded by soil on both sides, according to the preamble of claim 11.
EP 1 452 645 B2 discloses a method for forming a diaphragm wall in the ground, in which a trench cutter with rotationally driven cutting wheels is lowered into the ground, whereby soil material is removed and crushed. The removed soil material is mixed with a settable liquid inside the cutting trench, forming a so-called soil mortar. Before the soil mortar cures, the trench cutter is withdrawn again from the cutting trench filled with soil mortar. It is also possible to insert support beams into the soil mortar by using a crane before the soil mortar cures to the support wall.
A support wall of this type can be used, for example, to enclose a construction pit. The support wall can have a depth of 20 meters or more and a wall thickness of typically 0.5 meters to 2 meters.
Such a method for producing a support wall in the ground from a soil mortar is also referred to as the CSM™ technique.
In principle, it is also known by using a drilling and mixing auger and, in particular, an arrangement of parallel drilling and mixing augers arranged next to each other to form a supporting or drilling wall in the ground from a soil mortar in a similar way. In this process, the soil material removed during drilling is mixed with a settable liquid still in the borehole to form a soil mortar. To achieve a desired load-bearing capacity of the wall, support beams are inserted vertically into the soil mortar.
A major advantage of the method for forming a support wall with a soil mortar resides in that little or ideally no excavated soil material accrues that needs to be disposed of. This reduces transportation and landfill costs for removed soil material. In addition, a use of gravel and sand and the associated costs therewith are reduced accordingly or, ideally, avoided completely.
However, when using soil mortar, which is prepared in situ in a cutting trench or a drilled hole, no defined strength value can be assigned with regard to the shear force load to which a support wall in the ground is subjected. For this load, when constructing support walls with soil mortar, it is common practice to design and arrange support beams in the support wall in such a way that a required nominal wall stiffness is given and ensured already alone by the overall beam stiffness of the set support beams alone. The support beams are therefore of particular importance for a supporting function in the case of a support wall made of soil mortar.
Due to the nature of the method, the structure and composition of a soil mortar are not exactly known, so that other properties of the soil mortar are also uncertain, in particular the heat resistance in the event of fire and a permeability of de-icing salts. These properties are particularly then important if a support wall is partially exposed, for example in an excavation, and is also to remain on the structure while ensuring its supporting function.
To increase fire protection properties, it is known from DE 31 19 474 A1 to cast a steel girder in a concrete mass, wherein a concrete pillar is formed with a steel girder core. However, a beam made in this way has a relatively large and massive cross-section, so that such a beam cannot be set into a tough soil mortar material in the ground, or at best only with a great effort. A steel girder cast in concrete is also costly and would lead to a barely manageable weight with greater wall depths.
DE 10 2005 013 994 B4 discloses a lattice-like support for insertion into a soil mortar. Due to its structure of thin rods and binding plates, it can be easily inserted into a soil mortar compound. The bars can be coated with an anti-corrosion paint. There is no special fire protection.
The object underlying the invention is to specify a method and a support wall by means of which good economy in production and a particularly high level of safety are achieved in a support wall made of soil mortar.
This object is achieved, on the one hand, by a method having the features of claim 1 and, on the other hand, by a support wall having the features of claim 11. Preferred embodiments of the invention are specified in the dependent claims.
The method according to the invention is characterized in that a sheathing element made of concrete material is arranged on at least one support beam, and extends along an upper support beam section, and in that the support beam is set in the soil mortar in such a way that the upper support beam section with the sheathing element made of concrete material extends along the upper support wall section.
A basic idea of the invention resides in to attach a thin-walled sheathing element made of concrete material to a support beam made of a structural steel in certain areas, which sheathing element extends along an upper support beam section. Here, the support beam can be set in the soil mortar in such a way that the upper support beam section with the thin-walled sheathing element made of concrete material extends along the upper wall section. Here, the sheathing element can be configured and arranged in such a way that one narrow side of the thin-walled sheathing element is directed in an insertion direction during insertion or setting into the concrete mortar mass. The support beam can thus be inserted relatively easily into the tough concrete mortar material in the ground and sink into it.
A further aspect of the invention resides in that a sheathing element made of concrete material ensures a high corrosion protection property and also good fire protection property. Here, the sheathing element is mainly arranged on the upper section of the support beam which, after installation in the support wall, is located in the area which is exposed by the removal of soil material. The support beam with the sheathing element is in this process still surrounded by the soil mortar material. The sheathing element made of concrete material, additionally embedded in the concrete mortar material forms quasi an additional protective shield for the support beam against heat and the penetration of de-icing salts. The concrete material may contain cement with suitable admixtures and, if necessary, reinforcing elements.
According to one embodiment variant of the invention, it is particularly preferred that the lower support beam section is formed without a sheathing element from concrete and is arranged within the lower support wall section. The support beam can thus be set particularly easily in the soil mortar that has not yet set.
The support beam with the sheathing element can be suspended in the setting soil mortar compound in any desired position. The soil mortar material cures, so that the support beam is finally integrated into the support wall in the desired position. In this process, the support beam can be positioned in such a way that the at least one thin-walled sheathing element extends at least into the upper support wall section and protects the support beam in the area in which the support wall is exposed by the removal of soil material. According to one embodiment of the invention, it is particularly advantageous for the lower support beam section to be placed onto a soil bed. Thus, the support beam can preferably extend over the entire depth of the support wall in the ground, from the base up to close to the upper end.
A further advantageous embodiment of the invention resides in that the sheathing element is formed with a wall thickness of between 1 cm and 10 cm, preferably between 4 cm and 8 cm. The sheathing element can be formed in the shape of a sleeve or in another manner. The sheathing element can be attached to the support beam by casting it onto a region of the support beam or by a detachable connection, by means of screw, hook or other mechanical connections.
A further preferred embodiment of the invention resides in that the sheathing element is of plate-shaped design and is arranged at least on the side of the support beam which is directed towards a free side of the upper support wall section on which soil material is removed. The plate-shaped sheathing element is thus arranged between a free outer side of the support wall and the internal support beam and thus constitutes an additional barrier or protective shield against corrosive substances and/or against the effects of heat from outside.
The at least one plate-shaped sheathing element runs essentially parallel to an outer side of the support wall in a vertical direction. The sheathing element is embedded in the concrete mortar material in the ground.
According to a further development of the invention, it is in particular advantageous for applications in which the support wall is exposed in an upper area on both sides of the wall that at least two opposing plate-shaped sheathing elements, which run parallel to one another, are arranged on the support beam. This can provide particularly good protection on both sides of the internal support beam.
In principle, the support beam can be configured of structural steel in any suitable manner. According to one embodiment variant of the invention, it is preferred that the at least one support beam is formed as a solid, preferably rolled steel girder, in particular with an H, T, C or I profile, or as a lattice-like or scaffold-like beam of struts. A steel profile beam can be producted cost-effectively, wherein the thin-walled sheathing element is attached to the intended upper area, for example by screw or hook connections, before the steel profile beam is set into the concrete mortar substance. Alternatively, the support beam can be made of relatively thin steel struts or rods, which are bent and/or welded to get a lattice or scaffold-like structure.
The thin-walled sheathing element can be arranged on an outer side of the support beam produced in this way. Such a lattice-like or scaffold-like beam can be used particularly efficiently in a tough concrete mortar material to form a support wall in the ground.
In principle, the support wall in the ground can be made with the soil mortar in any suitable manner. According to an embodiment of the invention, it is particularly expedient for a cutting trench to be formed in the ground by cutting, with removed soil material being processed to the soil mortar in the cutting trench by feeding of and mixing with a cement suspension. The soil mortar is thus formed in situ within the cutting trench by mixing the milled soil material with the supplied cement suspension. The cement suspension can be fed directly into the area of the cutting wheels on a trench cutter. The cutting wheels can assume here multiple functions, namely cutting off the soil material and simultaneously mixing the soil material that has been cut off with the supplied cement suspension. In this way, a soil mortar can be made directly in the cutting trench in a particularly practical manner.
A further preferred embodiment variant of the invention resides in that a borehole is formed in the ground by drilling, with removed soil material being processed in the borehole to feed and mix with a cement suspension to the soil mortar. The borehole can be created, in particular by an earth drilling rig with an elongated drilling tool, which has a removal device on its underside for removing soil material. The removed soil material can be conveyed away into a rear area of the borehole via a screw conveyor. In this area, radially projecting mixing elements can be arranged on a drill string, through which the drilled out and crushed soil material is mixed with the supplied cement suspension to the soil mortar. The cement suspension can preferably be fed via a hollow drill string of the drilling tool and emerge into the borehole at the lower end of the drill string and/or through outlet openings along the drill string.
A particularly efficient method variant results in this context from the fact that several boreholes are formed by drilling next to each other in the ground to form the support wall. Therefore, the drilling tools can be arranged and configured parallel to each other in such a way that they create overlapping boreholes so that elongated slotted elements can be created in the ground.
Further, the invention relates to a support wall in the ground made of a soil mortar wherein the soil mortar in the ground is produced by mixing soil material and a cement suspension and is cured in the ground to the support wall, vertically directed support beams comprising a structural steel are set into the soil mortar in the ground prior to curing, and after curing, by removal of soil material, the support wall is exposed on at least one side along an upper support wall section, while a lower support wall section continues to be surrounded on both sides by ground, wherein a sheathing element made of concrete material is arranged on at least one support beam and extends along an upper support beam section, and in that the support beam is set into the soil mortar in such a way that the upper support beam section with the sheathing element made of concrete material extends along the upper support wall section. The support wall can be formed, in particular by the method according to the invention described before. This can result in the advantages described above.
According to one embodiment of the invention, it is particularly preferred that the lower support beam section is formed from concrete without a sheathing element and is arranged within the lower support wall section. The support beam can thus be set particularly easily into the soil mortar that has not yet set.
A further advantageous embodiment of the invention resides in that the sheathing element is formed with a wall thickness of between 1 cm and 10 cm, preferably between 4 cm and 8 cm. The sheathing element can be formed in the shape of a sleeve or in another manner. The sheathing element can be attached to the support beam by molding it onto a region of the support beam or by a detachable connection, by means of screw, hook or other mechanical connections.
A further preferred embodiment of the invention resides in that the sheathing element is of plate-shaped design and is arranged at least on the side of the support beam which is directed towards a free side of the upper support wall section on which soil material is removed. The plate-shaped sheathing element is thus arranged between a free outer side of the support wall and the internal support beam and thus constitutes an additional barrier or protective shield against corrosive substances and/or against the effects of heat from outside.
The invention is described in greater detail below with reference to preferred embodiments, which are shown schematically in the drawings. The drawings show in:
Subsequently, an excavation pit can be excavated up to an excavation pit base 9 by removing ground 5. Here, a lower support wall section 14 is still located within the ground 5 below the excavation pit base 9, while an upper support wall section 12 protrudes from the ground 5. The upper support wall section 12 is exposed on at least one side. In the illustrated exemplary embodiment, all sides of the upper support wall section 12 are exposed, as is clearly discernible.
Therefore, the support wall 10 can be integrated directly into a structure to be built, such as an underground garage wall.
In order to ensure sufficient resistance of the set support beam 20 against fire and the effects of de-icing salts, for example in accordance with the construction requirements, a sheathing element 30 is attached to the support beam 20 on at least one side, according to the invention. According to the exemplary embodiment shown, a plate-shaped sheathing element 30 can be attached to each of two opposite longitudinal sides of the support beam 20. The at least one sheathing element can preferably extend along the upper support beam section 22 from the excavation base 9 up to the upper end of the support wall 10.
In the exemplary embodiment shown, the set support beam 20 is made of vertical struts 25 and cross struts 26 made of a structural steel. The vertical struts 25 and the cross struts 26 can preferably be connected to one another by welding. At least one sheathing element 30 is attached to an upper support beam section 22 of the support beam 20 before it is set into the still soft soil mortar. In the illustrated exemplary embodiment, a plate-shaped sheathing element 30 is attached to each of the two long sides of the support beam 20, so that the support beam is supported on both sides in the upper support beam section 22.
Due to the preferably grid-like structure of the support beam 20 consisting of the vertical struts 25 and the cross struts 26 in combination with the laterally attached thin-walled sheathing elements 30 made of a concrete material, the support beam 20 can be further set with a relatively low resistance into a relatively tough soil mortar, preferably up to a soil bed 7 of the hole, wherein the support beam 20 is very well protected against heat and corrosion influences in its upper support beam section 22 by the at least one thin-walled sheathing element 30.
The at least one sheathing element 30 is configured and arranged in such a way, that the sheathing element 30 is located in the upper support wall section 12 of the support wall 10. The sheathing element 30 can extend to a certain, limited extent into the area in the ground 5. In contrast, the lower support beam section 24 is kept free of a sheathing element, as no additional protection is required in this area. This is because the lower support beam section 24 is the area of the support beam 20 which is located in the lower support wall section 14, which is still surrounded by ground 5 in its side area.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23179586.5 | Jun 2023 | EP | regional |
