Method for forming a retaining wall in the floor and retaining wall

Abstract

The invention relates to a method for forming a retaining wall in the ground from a soil mortar, which is produced in the ground by mixing soil material and a cement slurry. Vertically oriented support beams, which incorporate reinforcing steel, are set into the soil mortar in the ground before hardening. After hardening, soil material is removed along an upper section of the retaining wall, at least on one side, while a lower section of the retaining wall remains surrounded by soil on both sides. According to the invention, a thin-walled concrete shell element is attached to at least one support beam, extending along an upper section of the support beam. The support beam is set into the soil mortar such that the upper section of the support beam, together with the concrete shell element, extends along the upper section of the retaining wall.

Description

[0001] The invention relates to a method for forming a retaining wall in the ground from a soil mortar which is produced in the ground by mixing soil material and a cement suspension, wherein vertically directed support beams which comprise a structural steel are set into the soil mortar in the ground before hardening, and after hardening, soil material is removed along an upper retaining wall section at least on one side of the retaining wall, while a lower retaining wall section is further surrounded by soil on both sides, according to the preamble of claim 1.

[0002] The invention further relates to a retaining wall in the ground made of a soil mortar, wherein the soil mortar is produced in the ground by mixing soil material and a cement suspension and is hardened in the ground to form the retaining wall, before hardening, vertically directed support beams, which have a structural steel, are set into the soil mortar in the ground, and after hardening by removal of soil material, the retaining wall is exposed on at least one side along an upper retaining wall section, while a lower retaining wall section is further surrounded by soil on both sides, according to the preamble of claim 11.

[0003] EP 1 452 645 B2 discloses a method for constructing a diaphragm wall in the ground. In this method, a diaphragm wall cutter with rotating cutting wheels is lowered into the ground, removing and crushing soil material. The removed soil material is mixed with a setting liquid within the milled slot, forming a so-called soil mortar. Before the soil mortar hardens, the diaphragm wall cutter is withdrawn from the milled slot filled with soil mortar. Furthermore, it is possible to insert support beams into the soil mortar using a crane before the soil mortar hardens to form the retaining wall.

[0004] Such a retaining wall can, for example, serve as an excavation enclosure. The retaining wall can have a depth of 20 meters or more and a wall thickness of typically 0.5 meters to 2 meters.

[0005] Such a method for constructing a retaining wall in the ground using a soil mortar is also called the CSM ™< method.

[0006] In principle, it is also known to form a retaining or drilled wall in the ground from a soil mortar using a drilling and mixing auger, and in particular an arrangement of parallel, adjacent drilling and mixing augers. The soil material removed during drilling is mixed with a setting liquid while still in the borehole to form a soil mortar. To achieve the desired load-bearing capacity of the wall, support beams are inserted vertically into the soil mortar.

[0007] A major advantage of the method for constructing a retaining wall with soil mortar is that there is little, or ideally no, excavated soil waste that needs to be disposed of. This reduces transport and landfill costs for excavated soil. Furthermore, the consumption of gravel and sand and the associated costs are reduced accordingly, or ideally even eliminated entirely.

[0008] However, when using soil mortar, which is created in situ in a milled trench or a borehole, no defined strength value can be assigned with regard to the shear force load to which a retaining wall is exposed in the soil. When constructing retaining walls with soil mortar, it is common practice to design and arrange the support beams in such a way that the required target wall stiffness is achieved and ensured solely by the overall stiffness of the installed support beams. The support beams are therefore of particular importance for the supporting function of a retaining wall made of soil mortar.

[0009] Due to the process involved, the structure and composition of a soil mortar are not precisely known, so other properties of the soil mortar are also uncertain, particularly its heat resistance in the event of fire and its permeability to de-icing salts. These properties are particularly important when a retaining wall, such as in an excavation pit, is partially exposed and is intended to remain in place while maintaining its supporting function.

[0010] To increase fire protection properties, it is known from DE 31 19 474 A1 to cast a steel girder into a concrete mass, forming a concrete column with a steel girder core. However, a girder produced in this way has a relatively large and massive cross-section, making it impossible to install such a girder into a tough soil mortar mass, or at least only with considerable effort. A steel girder cast into concrete is also costly and, with greater wall depths, would result in a weight that would be almost impossible to handle.

[0011] DE 10 2005 013 994 B4 describes a lattice-like support for insertion into soil mortar. Due to its construction of thin bars and connecting plates, it can be easily inserted into a soil mortar. The bars can be coated with an anti-corrosive paint. No special fire protection is provided.

[0012] The invention is based on the TaskThe aim is to specify a method and a retaining wall with which good cost-effectiveness in production and a particularly high level of safety can be achieved for a retaining wall made of soil mortar.

[0013] The object is achieved, on the one hand, by a method having the features of claim 1 and, on the other hand, by a retaining wall having the features of claim 11. Preferred embodiments of the invention are specified in the dependent claims.

[0014] The method according to the invention is characterized in that a casing element made of concrete material is arranged on at least one support beam, which casing element 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 casing element made of concrete material extends along the upper support wall section.

[0015] A basic idea of ​​the invention is to attach a thin-walled casing element made of concrete material to a support beam made of structural steel, said casing element extending along an upper support beam section. The support beam can be inserted into the soil mortar such that the upper support beam section, with the thin-walled casing element made of concrete material, extends along the upper wall section. The casing element can be designed and arranged such that a narrow side of the thin-walled casing element is directed in an insertion direction during insertion or insertion into the concrete mortar mass. The support beam can thus be inserted relatively easily into the viscous concrete mortar mass in the soil and sink into it.

[0016] A further aspect of the invention is that a casing element made of concrete material ensures high corrosion protection properties and also good fire protection properties. The casing element is arranged primarily on the upper section of the support beam, which, after installation in the retaining wall, lies in the area exposed by the removal of soil material. The support beam with the casing element is further surrounded by the soil mortar mass. The casing element made of concrete material, which is additionally embedded in the concrete mortar mass, forms an additional protective shield for the support beam against heat and the penetration of de-icing salts. The concrete material can comprise cement with suitable admixtures and, if necessary, reinforcing elements.

[0017] According to one embodiment of the invention, it is particularly preferred that the lower support beam section be formed without a concrete casing element and be arranged within the lower retaining wall section. The support beam can thus be inserted particularly easily into the not yet set soil mortar.

[0018] The support beam with the casing element can be suspended in the setting soil mortar mass in any desired position. The soil mortar mass hardens, so that the support beam is finally integrated into the retaining wall in the desired position. The support beam can be positioned such that the at least one thin-walled casing element extends at least into the upper retaining wall section and protects the support beam in the area in which the retaining wall is exposed by removal of soil material. According to one embodiment of the invention, it is particularly advantageous that the lower support beam section is placed on a soil base. Thus, the support beam can preferably extend over the entire depth of the retaining wall in the soil, from the base to almost the upper end.

[0019] A further advantageous embodiment of the invention is that the casing element is formed with a wall thickness between 1 cm and 10 cm, preferably between 4 cm and 8 cm. The casing element can be sleeve-shaped or designed in another manner. The casing element can be attached to the support beam by casting it onto a portion of the support beam or by detachably connecting it to the support beam using screws, hooks, or other mechanical connections.

[0020] A further preferred embodiment of the invention is that the casing element is plate-shaped and is arranged at least on the side of the support beam that faces a free side of the upper retaining wall section, where soil material is removed. The plate-shaped casing element is thus arranged between a free outer side of the retaining wall and the inner support beam, thus providing an additional barrier or protective shield against corrosive substances and / or external heat effects.

[0021] The at least one plate-shaped casing element runs essentially parallel to an outer side of the retaining wall in a vertical direction. The casing element is embedded in the concrete mortar mass in the soil.

[0022] Particularly for applications in which the supporting wall is exposed in an upper area on both sides of the wall, a further development of the invention advantageously provides at least two opposing plate-shaped casing elements arranged parallel to each other on the supporting beam. This provides particularly good two-sided protection for the internal supporting beam.

[0023] In principle, the support beam can be constructed from structural steel in any suitable manner. According to one embodiment of the invention, it is preferred that the at least one support beam is constructed as a solid, preferably rolled steel beam, in particular with an H-, T-, C-, or I-shaped profile, or as a lattice-like or framework-like beam made of struts. A steel profile beam can be produced cost-effectively, with the thin-walled casing element being attached to the intended upper region, for example by screw or hook connections, before the steel profile beam is set in the concrete mortar mass. Alternatively, the support beam can be made from relatively thin steel struts or bars, which are given a lattice-like or framework-like structure by bending and / or welding.

[0024] The thin-walled shell element can be arranged on an outer side of the support beam thus produced. Such a lattice-like or scaffold-like beam can be used particularly efficiently in a tough concrete mortar mass to form a retaining wall in the ground.

[0025] In principle, the retaining wall can be constructed in the ground using soil mortar in any suitable manner. According to one embodiment of the invention, it is particularly expedient for a milling slot to be formed in the ground by milling, whereby removed soil material in the milling slot is processed into the soil mortar by feeding and mixing it with a cement suspension. The soil mortar is thus formed in situ within the milling slot by mixing the milled soil material with the added cement suspension. The cement suspension can be fed directly into the area of ​​the milling wheels at a diaphragm wall cutter. The milling wheels can perform multiple functions, namely milling away the soil material and simultaneously mixing the milled soil material with the added cement suspension. This allows a soil mortar to be created directly in the milling slot in a particularly expedient manner.

[0026] A further preferred embodiment of the invention consists in creating a borehole in the ground by drilling, wherein removed soil material in the borehole is processed to supply and mix with a cement suspension to form the soil mortar. The borehole can be created in particular by an earth drilling device with an elongated drilling tool which has an removal device on its underside for removing soil material. The removed soil material can be conveyed away via a conveyor screw into a rear region of the borehole. In this region, mixing elements projecting radially on a drill string can be arranged, by means of which mixing elements the drilled-out and crushed soil material is mixed with the supplied cement suspension to form the soil mortar.The cement suspension can preferably be supplied via a hollow drill string of the drilling tool and exit into the borehole at the lower end of the drill string and / or through outlet openings along the drill string.

[0027] A particularly efficient method variant is achieved by drilling several boreholes next to each other in the ground to form the retaining wall. The drilling tools can be arranged and designed parallel to each other so that they create overlapping boreholes, allowing elongated slot elements to be created in the ground.

[0028] material, that the support beam is set into the soil mortar in such a way that the upper support beam section with the casing element made of concrete material extends along the upper retaining wall section. The retaining wall can be formed, in particular, by the method according to the invention described above. This can result in the advantages described above.

[0029] According to one embodiment of the invention, it is particularly preferred that the lower support beam section be formed without a concrete casing element and be arranged within the lower retaining wall section. The support beam can thus be inserted particularly easily into the not yet set soil mortar.

[0030] A further advantageous embodiment of the invention is that the casing element is formed with a wall thickness between 1 cm and 10 cm, preferably between 4 cm and 8 cm. The casing element can be sleeve-shaped or designed in another manner. The casing element can be attached to the support beam by casting it onto a portion of the support beam or by detachably connecting it to the support beam using screws, hooks, or other mechanical connections.

[0031] A further preferred embodiment of the invention is that the casing element is plate-shaped and is arranged at least on the side of the support beam that faces a free side of the upper support wall section, where soil material is removed. The plate-shaped casing element is thus arranged between a free outer side of the support wall and the inner support beam, thus providing an additional barrier or protective shield against corrosive substances and / or external heat effects.

[0032] The invention is further described below with reference to preferred embodiments, which are schematically illustrated in the drawings. In the drawings: Fig. 1 is a plan view of a retaining wall according to the invention; Fig. 2 is a front view of the retaining wall from Fig. 1 ; and Fig. 3 a side view of the retaining wall of the Figures 1 and 2 .

[0033] In the Figures 1 to 3 A highly schematic representation of a part of a retaining wall 10 according to the invention is shown in various views. The retaining wall 10 is first constructed entirely in the ground 5. The retaining wall 10 is constructed in a generally known manner from a soil mortar in the ground 5. A hole is created by milling or drilling, wherein the soil material removed in the process is mixed, preferably in situ within the hole, with a cement suspension to form the soil mortar. In the hole thus created, which is in the Figures 1 to 3 a milled slot with a rectangular cross-section, the in-situ produced soil mortar can harden to form a solid retaining wall 10. Before hardening, at least one support beam 20 can be inserted into the still soft soil mortar.

[0034] Subsequently, an excavation pit can be excavated down to a pit base 9 by removing soil 5. A lower retaining wall section 14 remains within the soil 5 below the pit base 9, while an upper retaining wall section 12 protrudes from the soil 5. The upper retaining wall section 12 is exposed on at least one side. In the illustrated embodiment, all sides of the upper retaining wall section 12 are clearly exposed.

[0035] The retaining wall 10 can be directly integrated into a structure to be constructed, such as an underground parking garage wall.

[0036] To ensure sufficient resistance of the installed support beam 20, for example, in accordance with construction requirements against fire and the effects of de-icing salts, according to the invention, a casing element 30 is attached to at least one side of the support beam 20. According to the illustrated embodiment, a plate-shaped casing element 30 can be attached to each of two opposite longitudinal sides of the support beam 20. The at least one casing element can preferably extend along the upper support beam section 22 from the excavation floor 9 to the upper end of the retaining wall 10.

[0037] In the illustrated embodiment, the installed support beam 20 is made of structural steel, consisting of vertical struts 25 and cross struts 26. The vertical struts 25 and the cross struts 26 can preferably be connected to one another by welding. At least one casing element 30 is attached to an upper support beam section 22 of the support beam 20 before being inserted into the still-soft soil mortar. In the illustrated embodiment, a plate-shaped casing 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.

[0038] Due to the preferably lattice-like structure of the support beam 20 comprising the vertical struts 25 and the cross struts 26 in combination with the laterally mounted thin-walled casing elements 30 made of a concrete material, the support beam 20 can be further inserted into a relatively tough soil mortar, preferably down to a bottom base 7 of the hole, with relatively low resistance, wherein the at least one thin-walled casing element 30 of the support beam 20 in its upper support beam section 22 is very well protected against heat and corrosion influences.

[0039] The at least one casing element 30 is designed and arranged such that the casing element 30 is located in the upper supporting wall section 12 of the supporting wall 10. The casing element 30 can extend to a certain, limited extent into the area in the floor 5. In contrast, the lower support beam section 24 is kept free of a casing element, since 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 that is located in the lower supporting wall section 14, which is still surrounded by the floor 5 in its lateral region.

Claims

1. Method for forming a support wall (10) in the ground (5) from a soil mortar which is made in the ground (5) by mixing soil material and a cement suspension, wherein vertically directed support beams (20) comprising a structural steel in that are set soil mortar in the ground (5) prior to curing, and after curing, soil material is removed along an upper support wall section (12) on at least one side of the support wall (10), while a lower support wall section (14) continues to be surrounded by ground (5) on both sides, characterized in that a thin-walled sheathing element (30) made of concrete material is attached to at least one support beam (20), which sheathing element extends along an upper support beam section (22), and that the support beam (20) is set in the soil mortar in such a way that the upper support beam section (22) with the sheathing element (30) made of a concrete material extends along the upper support wall section (12).

2. Method according to claim 1, characterized in that the lower support beam section (24) is formed from concrete material without a sheathing element (30) and is arranged within the lower support wall section (14).

3. Method according to claim 1 or 2, characterized in that the lower support beam section (24) is placed onto a soil bed (7).

4. Method according to any one of claims 1 to 3, characterized in that the sheathing element (30) is formed with a wall thickness of between 1 and 10 cm, preferably between 4 and 8 cm.

5. Method according to any one of claims 1 to 4, characterized in that the sheathing element (30) is of plate-shaped design and is arranged at least on the side of the support beam (20) which is directed towards a free side of the upper support wall section (12) on which soil material is removed.

6. Method according to any one of claims 1 to 5, characterized in that at least two opposing plate-shaped sheathing elements (30), which extend parallel to one another, are arranged on the support beam (20).

7. Method according to any one of claims 1 to 5, characterized in that the at least one support beam (20) is configured as a solid steel girder, in particular with an H, T, C or I profile, or as a lattice-like or scaffold-like beam of struts (25, 26).

8. Method according to any one of claims 1 to 7, characterized in that a cutting trench is formed in the ground (5) by cutting, wherein removed soil material in the cutting trench is processed into the soil mortar by feeding of and mixing with a cement suspension.

9. Method according to any one of claims 1 to 8, characterized in that a borehole is formed in the ground (5) by drilling, wherein the removed soil material in the borehole is processed to the soil mortar by feeding of and mixing with a cement suspension.

10. Method according to claim 9, characterized in that several boreholes are formed next to one another in the ground (5) by drilling, in order to form the support wall (10).

11. Support wall in the ground (5) made of a soil mortar, in particular formed by a method according to any one of claims 1 to 10, wherein the soil mortar in the ground (5) is produced by mixing soil material and a cement suspension and is cured in the ground (5) to the support wall (10), vertically directed support beams (20) comprising a structural steel are set into the soil mortar in the ground (5) prior to curing, and after curing, by removal of soil material, the support wall (10) is exposed on at least one side along an upper support wall section (12), while a lower support wall section (14) continues to be surrounded on both sides by ground (5), characterized in that a sheathing element (30) made of concrete material is arranged on at least one support beam (20) and extends along an upper support beam section (22), and in that the support beam (20) is set into the soil mortar in such a way that the upper support beam section (22) with the sheathing element (30) made of concrete material extends along the upper support wall section (12).

12. Support wall according to claim 11, characterized in that a lower support beam section (24) is formed without a sheathing element (30) from concrete material and is arranged within the lower support wall section (14).

13. Support wall according to claim 11 or 12, characterized in that the sheathing element (30) is formed with a wall thickness of between 1 and 10 cm, preferably between 4 and 8 cm.

14. Support wall according to any one of claims 11 to 13, characterized in that the sheathing element (30) is of plate-shaped design and is arranged at least on the side of the support beam (20) which is directed towards a free side of the upper support wall section (12) on which soil material is removed.

Images