DE8713006U1 - Shoring support - Google Patents

Description

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Description

The invention relates to a shoring support for an excavation shoring system.

Excavations for the construction of basements of high-rise buildings, for the construction of underground car parks and subway tunnels in inner-city areas generally require vertical support, as there is usually very little space available, so that the excavation pit boundaries cannot be constructed using natural, stable slopes. A very frequently used type of excavation pit shoring is carried out using shoring beams made of various types of steel profiles and infills made of wood, concrete or steel arranged between these beams. The shoring beams are either driven in or placed in large-hole bores. During the excavation of the excavation pit, the spaces between the shoring beams are infilled. There are known shoring supports that are made up of two commercially available U-profiles, with the webs of the U-profiles arranged parallel to each other at a distance, the total of 4 flanges facing outwards and the flanges lying in one plane connected by welded-on binding plates. The binding plates are arranged on both sides of the shoring support at a distance of approx. 1.50 m over the entire length of the shoring support. The known shoring support is placed in a borehole, which is then filled again.

The disadvantages of the known shoring beam are the complex manual welding work, its low bending stiffness in the direction of the flanges and its low torsional stiffness. The low bending stiffness in the direction of the flanges and the low torsional stiffness often have a negative effect on transport and installation. The shoring beam often has to be placed in a cased borehole, the casing of which can only be pulled out after the cavities have been filled.

Since the casing is usually pulled while the drill pipe is rotating, large torsional stresses are created for the shoring support, which can lead to the

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Weld seams of the binding plates can lead to. Another disadvantage of the known retaining beam is the open space between the webs of the two U-profiles. This open space does indeed bring advantages when setting ground anchors, as this form of retaining beam does not require straps. However, there is no infill in the area of the open space. When the excavation pit is dug, the filling material trickles into the pit, the retaining beam loses its support against the soil to be supported, so that soil movements and subsidence outside the excavation pit cannot be avoided. The aim is to avoid this by using a lime-cement-sand mixture as a filling material, for example, which is stable despite its low strength. However, this makes it difficult or impossible to recover the retaining beam.

DE-AS 20 39 386 describes a shoring beam that has a hat-shaped profile. This shoring beam is made in one piece and is rolled. Its cross-sectional shape is statically very unfavorable. The small area of the profile rear wall and the connecting flanges in the overall cross-section results in only low section moduli. The unfavorable ratio of bending stiffness to weight per meter is therefore uneconomical. The most frequently used shoring beams are in the cross-sectional height range of 300 to 400 mm. A one-piece rolled beam of this cross-sectional height with a right angle between webs and flanges cannot be produced using rolling technology. However, even small deviations from the right angle greatly increase the bending stresses at the transition between the profile rear wall and the profile side walls, which leads to a reduction in the load that can be absorbed from earth pressure compared to an exactly right-angled corner design. All these disadvantages have led to the fact that the one-piece rolled hat-shaped shoring support profile has not been adopted in practice.

The invention is based on the object of specifying a shoring support for an excavation pit shoring which has an optimal ratio of bending stiffness to weight per meter, which can be manufactured industrially and which makes installation and removal more economical.

This object is achieved by the characterizing part of claim 1. Further advantageous embodiments of the invention are specified in the subclaims.

* The most important requirements for an optimal cross-sectional shape of a shoring beam are maximum bending stiffness and torsional stiffness with the lowest material consumption and the smallest external dimensions. This is achieved by high, thin webs and narrow, thick flanges. For the main application area of shoring beams, web heights of approx. 300 to 400 mm are required. The appropriate flange width is approx. 100 to 120 mm, depending on the required support depth of the infills. The optimal cross-sectional shape will have flange thicknesses that are more than twice the web thickness. A preferred design of the test-based shoring beam ^is

made from 2 z-shaped rolled profiles, the dimensions of which can be easily optimized by adjusting the rollers accordingly. The *- welded joint (4) is preferably produced mechanically in the rolling mill using the submerged arc welding process. Depending on the static and structural requirements of the shoring support, the most cost-effective design of the welded joint (4) can be selected, as specified in the subclaims.

A significant advantage of the shoring beam according to the invention is its concave shape. In addition to increasing the bending stiffness in the direction of the construction plane and its torsional stiffness, there are significant advantages in handling the shoring beam. Its narrow shape, due to only 2 protruding flanges on one side, enables smaller boreholes to be made when the shoring beam is used as a drilling beam. This results in lower drilling and backfilling costs. Smaller boreholes also result in less soil loosening in the drilling area, which is important for excavation shoring near existing buildings due to possible building settlement. It is also possible to fill the borehole only on the side to be supported. With a continuous weld seam, the shoring beam can also be made watertight, which enables the construction of a watertight shoring.

A further preferred embodiment of the shoring beam provides for a parallel arrangement of the webs (5) and a right-angled connection of the flanges (3) to the webs (5). The parallel arrangement of the webs (5) enables the structurally simple arrangement of ground anchors within the shoring beam, whereby the anchor head is supported, for example, on Q steel plates (11) which are connected to the

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both webs are welded. Attaching the anchor heads directly to the rear flanges is undesirable, as the ground anchors are usually burned off when the baaa is removed and the rear flanges would be damaged in the process*

The shoring support according to the invention can be driven in or inserted into boreholes.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments, which are explained in more detail with reference to the drawings.

Show it:

Fig. I a cross-section of the shoring beam

Fig. II a welded connection of the shoring beam

Fig. III a flange design of the shoring beam

Fig. IV a welded joint arrangement

Fig, V a shoring beam with attached ground anchor

Fig. VI Horizontal section to Fig. V

Fig. VII a shoring beam with countersunk ground anchor head

Fig. VIII Horizontal section to Fig. VII

Fig. IX Representation of the required borehole diameter

Fig. X Borehole filling area

The cross-section of a shoring beam shown in Fig. I is composed of 2 Z'-shaped rolled profiles (1). The webs (5) are arranged parallel, the flanges (3) are arranged at right angles to the webs (5). The welded joint (4) is designed as a V-seam on one side, with the Z-shaped rolled profiles (1) providing a bevel (6) for this purpose. The Z-shaped rolled profile (1) is formed point-symmetrically, which is why one profile shape is sufficient to produce a vertex shoring beam.

Fig. II shows a double-sided welded joint (4) in the form of 2 V-seams. For this, the z-shaped profile with 2 folds (6) on the flanges (3) &Idigr; is manufactured according to Fig. III.

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Fig. IV shows a shoring view of the welded joint side with a welded joint in sections (7).

Figures V and VI show a shoring beam with a ground anchor head (8) placed on the flanges (3). The anchor bracket (9) is a solid sheet that is welded to the flanges (3) and is used for assembly purposes and to absorb the vertical component of the anchor force. If necessary, binding plates (10) can be welded to the flanges (3) on the excavation side in order to increase the rigidity of the shoring beam in the direction of the shoring plane.

Fig. VII and VIII show the arrangement of a countersunk anchor head within the shoring beam. This design is used when the building wall is concreted directly onto the shoring without any working space ("Berlin shoring"). Two steel plates (11) welded to the webs (5) on both sides serve as supports for the anchor head, which consists of a support plate (12), a wedge disk (13), the anchor ring (14) and the wedges (15). If necessary, the shoring beam can be stiffened on its open side in the direction of the shoring plane, for example by sections (16) of a U-profile welded to the webs (5) on both sides.

Fig. IX shows the reduction in the external diameter of the shoring support according to the invention compared to an equivalent shoring support composed of 2 U-profiles. On average, the borehole can be made with a diameter that is 20 % smaller.

Fig. X shows the necessary area (18) that must be refilled when placing the shoring support in a borehole. The area (19) can remain free, so that savings in filling material of approx. 30 to 50% are possible.

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Claims (14)

Expectations 1. Shoring support for an excavation shoring, characterized in that two z-shaped steel profiles (1) are joined together to form a hat-shaped profile, whereby the narrow sides (2) of two flanges (3) touch each other, and the two z-shaped steel profiles (1) are connected at the point of contact by a welded joint (4). 2. Shoring support according to claim 1, characterized in that the welded connection (4) at the contact point is arranged continuously on one side over the entire length of the shoring support. 3. Shoring support according to claim 1, characterized in that the welded connection (4) at the contact point is arranged on one side only in partial sections (7) over the length of the shoring support. 4. Shoring support according to claim 1, characterized in that the welded connection (4) is arranged continuously at the contact point on both sides over the entire length of the shoring support. 5. Shoring support according to claim 1, characterized in that the welded connection (4) is arranged on both sides only in partial sections (7) over the length of the shoring support. /2 6. Shoring support according to claim 1 and 3, characterized in that the welded connection (4) is arranged on one side only in partial sections (7) over the length of the shoring support, the partial sections (7) being arranged alternately on the inside and on the outside of the shoring support. 7. Shoring support according to claims 1 to 6, characterized in that the Z-shaped steel profiles are rolled profiles. 8. Shoring support according to claim 1 to 6, characterized in that the Z-shaped steel profiles are produced by cold forming. 9. Shoring support according to claims 1 to 8, characterized in that the flanges (3) are arranged at a right angle to the webs (5) of the Z-shaped steel profiles (1). 10. Shoring support according to claims 1 to 9, characterized in that the 2 webs (5) of the Z-shaped steel profiles are arranged parallel to each other. 11. Sheathing support according to claims 1 to 10, characterized in that the narrow sides (2) of the Z-shaped profiles U) have a broken edge (6) on one side. 12. Installation rack according to claims 1 to 10, characterized in that the narrow sides (2) of the Z-shaped profiles (1) have broken edges (6) on two sides. 13. A support according to claim 1 to 12, characterized in that the thickness of the flanges (3) is greater than the thickness of the webs (5). 14. A support according to claim 1 to 13, characterized in that the welded connection (4) is produced using the underlay welding process. al &igr;&igr;&igr;&igr;