ANCHOR ARRANGEMENT AND ANCHOR METHODS

Description

[0001] The invention relates to an anchor arrangement with an anchor which is designed to be inserted into a borehole in the ground and has an elongated tension element which has a base section which is designed to be anchored in the ground by injecting a settable injection medium, a middle section which is designed to be arranged in the ground together with the base section, and a head section which is arranged outside the borehole and has a tensioning device for applying a tensile stress, according to the preamble of claim 1. Such a device is generally known and is presented, for example, in the document EP 3 336 259 A1.

[0002] The invention further relates to an anchoring method in which an anchor with an elongated tension element is introduced into a borehole in the ground and a base section of the tension element is anchored in the ground by injecting a setting injection medium, a tensile stress is applied to a head section of the tension element outside the borehole by means of a tensioning device and finally the tensile stress in the tension element is reduced again, according to the preamble of claim 10.

[0003] Anchor assemblies are used primarily for the back-anchoring of retaining walls in excavations. Through the appropriate arrangement and number of anchors, also called tension anchors, the compressive forces exerted by the surrounding soil on a retaining wall can be diverted back into the surrounding soil. For this purpose, anchors with tension elements are drilled into the soil area to be supported. A base section of the tension element is anchored in the soil by injecting cement mortar. After curing, a tensioning device can be used to apply tensile stress to the head of the anchor, for example, to back-anchor a retaining wall in the soil.

[0004] The tension elements used for this purpose can be several meters long and reach total lengths of 20 meters or more. In many cases, the tension elements extend into neighboring building plots or areas of land that are themselves intended for future construction projects.

[0005] Construction authorities may therefore stipulate in anchor regulations that existing tension elements of anchors be released for safety reasons before the completion of a civil engineering project and the closure of the excavation pit. In some cases, it may be necessary to remove at least part of a tension element from the ground.

[0006] If it is necessary to remove a tension element completely or at least partially from the ground, it is known to arrange a heating device, in particular with an electric heating coil, as close as possible to the base section of the tension element when inserting the tension element into a borehole. The heating device can heat and warm an impact point on the tension element such that the tension element melts and tears at the impact point, thus separating it from the base section anchored in the ground with cement mortar. The separated, free part of the tension element can then be pulled out of the ground and removed.

[0007] In other cases, it is sufficient to simply release the tension from the tension elements. To release tension from a tension element that can remain in the ground, it is common practice to partially or completely cut off the head section of the tension element protruding from the borehole, particularly using a cutting torch. This is done manually by a construction worker and does not require any special precautions at the head section of the tension element.

[0008] In many cases, a structure is constructed within an excavation pit close to the anchored retaining wall, making it impossible for construction workers to access certain areas of the retaining wall. In these cases, anchors must not be placed so that their head sections are located in these inaccessible areas. This means that the arrangement and number of anchors can no longer be selected based on a structurally favorable location, but must be placed in such a way that access to the head sections is still possible.

[0009] This can result in considerable additional expenditure for additional and / or larger anchors for excavation support, in order to ensure sufficient support on the one hand and access to the head sections of the anchors for stress relief on the other.

[0010] The invention is based on the TaskThe aim is to provide an anchor arrangement and an anchor method which enables efficient arrangement and relaxation of the anchors even in the case of structural restrictions.

[0011] According to the invention, the object is achieved on the one hand by an anchor arrangement having the features of claim 1 and on the other hand by an anchor method having the features of claim 10. Preferred embodiments are specified in the respective dependent claims.

[0012] The anchor arrangement according to the invention is characterized in that a stress relief device is arranged in the region of the head section and is designed to specifically reduce the strength of the tension element at an action point to a reduced strength state, in which the tension element is plastically deformed at the action point by the applied tensile stress in order to reduce the stress.

[0013] A basic idea of ​​the invention is to depart from the usual use of a cutting torch for stress relief of an existing armature and to arrange a stress relief device on the armature head section, with which the tension element is plastically deformed at the point of action. The plastic deformation, in particular a permanent lengthening of the tension element, reduces the tensile stresses. The head section is designed in particular to form a receiving space for the preferably electrically operated stress relief device. This can be operated by a worker even from a greater distance. Direct access by an operator to the head section is therefore not necessary, as would be necessary when using a manually operated cutting torch.

[0014] If the tension-relieving device deliberately reduces the strength of the tension element in the area of ​​the impact point, the tension element can undergo plastic deformation, allowing the tensile stress between the head section with the tensioning device and the anchored base section to be reduced. This reduction in strength can lead to significant elongation and, in extreme cases, to the existing tensile stresses, even to the tearing or severing of the tension element at the impact point.

[0015] By arranging a stress-relieving device in the area of ​​the head section, a structure can be constructed within an excavation pit up to close to the head section, with subsequent stress-relieving of at least one anchor then taking place via the stress-relieving device arranged on the anchor. Furthermore, the arrangement according to the invention eliminates the need for a construction worker to manually stress-relieve the anchor with a cutting torch, which increases occupational safety and simplifies and accelerates the process of stress-relieving an anchor overall.

[0016] In principle, the stress relief device can be positioned directly adjacent to the head section. According to one embodiment of the invention, it is particularly preferred that, when the anchor is installed in the ground, the impact point with the stress relief device is located outside the borehole. The stress relief device is formed, in particular, directly on the head section and is located outside the ground or an excavation pit wall. The stress relief device is thus particularly easily accessible. The stress relief device can be installed during the formation of the anchor or subsequently, in particular immediately before the anchor is stress relieved.

[0017] According to a further embodiment of the invention, it is advantageous for the tension element or tension members to be formed by one or more wire strands and / or metal rods. These elements allow for efficient transmission of even high tensile stresses.

[0018] Furthermore, it is preferred that the stress-relieving device be fixedly or detachably attached to the head section. In principle, induction coils, such as heating devices, can be mass-produced relatively inexpensively as stress-relieving devices, so that they can remain on the armature even after the stress has been relieved, for cost reasons. Alternatively, the stress-relieving device can also be detachably arranged, so that it can be removed after the stress has been relieved and reused on a different armature.

[0019] According to a further embodiment of the invention, it is preferred that the tensioning device comprises an anchor plate, which is supported against the ground and has a passage for the tension element, and a tension head, to which the tension element is attached and which is supported on the anchor plate, wherein the tension element can be tensioned relative to the anchor plate. The anchor plate can rest directly on a surface of the ground or on a retaining wall, thus indirectly supporting itself against the ground. Thus, via the anchor plate, a force exerted by the ground on the retaining wall can be absorbed by the tension element and diverted into the ground.

[0020] It is particularly advantageous that the stress relief device and, optionally, a receiving ring for the stress relief device are arranged between the anchor plate and the clamping head. Thus, in this preferred variant, the point of action for generating the plastic deformation is located between the anchor plate and the clamping head. For this purpose, a receiving ring with a receiving space for the stress relief device can be arranged between the anchor plate and the clamping head. The receiving ring is designed accordingly for force transmission between the clamping head and the anchor plate.

[0021] The stress-relieving device, in particular a heating coil and / or an electrode arrangement with or without a corrosion aid, can be arranged within the receiving ring close to the tension element, which is surrounded by the stress-relieving device. Preferably, the stress-relieving device is located within an outer annular wall of the receiving ring. The stress-relieving device can be arranged therein in a fixed or detachable manner.

[0022] In principle, the clamping device and, in particular, the clamping head can be designed in any known and suitable manner. According to one embodiment of the invention, it is particularly expedient for the clamping head to be designed as a wedge support with at least one conical receiving hole for at least one clamping cone on the tension element or tension members. This allows for a particularly compact and reliable connection between the tension element and the clamping head and enables the transmission of relatively high forces.

[0023] When using an induction coil for inductive heating of the tension element, the tension element is particularly made of a metallic material suitable for inductive heating. According to a further development of the invention, it is particularly preferred for the tension element to have two or more tension members. In particular, a tension element can be formed by several tension members arranged in a bundle.

[0024] A preferred embodiment of the anchor arrangement according to the invention consists in that the stress relief device is designed as a heating device, in particular with at least one electrically operated induction coil, which is designed to heat the tension element of at least one tension member at the point of action to a softening temperature at which plastic deformation occurs. With a heating device, heating of the tension element in the region of the point of action and thus plastic deformation can be achieved. Due to the plastic deformation, the tensile stresses in the tension element can be reduced by expansion between the head section with the tensioning device and the anchored foot region. The softening can occur up to the point of melting of the material of the tension element. In particular, heating can be achieved by means of an induction coil by inductive heating of a metallic tension element.

[0025] Alternatively or additionally, according to a further embodiment of the invention, the stress relief device can be designed as a corrosion device with an electrode arrangement which is designed to generate a corrosion voltage at the point of action. With a corrosion device, a targeted and accelerated corrosion of the material of the tension element can be brought about at the point of action. The corrosion reduces the strength of at least parts of the tension element, so that plastic deformation can occur due to the applied tensile stress in the region of the point of action. Through plastic deformation, in particular stretching, the applied tensile stresses can be reduced and the anchor can thus be relieved as a whole.

[0026] If the tension element consists of multiple tension members, the stress relief device can be installed on only one or more tension members. If individual tension members are stretched and possibly even severed, the tensile stress on the remaining tension members increases, so that the resulting increase in stress in an individual tension member exceeds the material's deformation limit, and more or less severe plastic deformation may occur, possibly leading to the rupture of the remaining tension member(s).

[0027] A preferred embodiment further comprises the corrosion device having at least one corrosion aid arranged at the point of action and comprising, in particular, a salt. The corrosion aid can, in particular, be a solid or gel-like chemical substance that supports a corrosive effect or triggers it in combination with an applied electrical voltage. The aid can, in particular, be a salt or a chemical substance that causes or supports a corresponding ion exchange during a corrosion process. The corrosion aid can, in particular, be designed as a solid block or in a ring shape, which is attached to the tension element in the region of the point of action together with the electrode arrangement. In principle, the corrosion device can also comprise a supply line for supplying a liquid corrosion aid to the point of action.However, a corrosion aid is not absolutely necessary, especially if, after completion of the construction work, the area around the head section is filled with earth or a similar material that supports a corrosion effect.

[0028] When using a corrosion device, the stress reduction can extend over a longer period, which may include several days or weeks. This period is sufficient to achieve the desired goal of stress reduction. This period, during which the original ground pressure can be restored and also act on the structure, is particularly gentle on the structure and the surrounding area. Preferably, a measuring device, such as a stress measuring sensor, can be arranged on the anchor assembly. This measuring device can be used to detect and thus document the stress reduction of the anchor, either wired or wirelessly.

[0029] The invention further relates to an anchoring method which is characterized in that the anchoring arrangement according to the invention is formed, wherein a relaxation device is arranged in the region of the head section and a strength of the tensile element at an action point of the tensile element is reduced to a strength state in which the tensile element is plastically deformed at the action point by the tensile stress, wherein the tensile stress in the tensile element is reduced.

[0030] With this anchoring method according to the invention, the advantages described above can be achieved.

[0031] According to one embodiment of the invention, it is preferred that the relaxed tension element remains in the ground. In particular, the head section with the tensioning device and / or the relaxation device can also remain in or on the ground. Thus, in particular, relaxation of the tension element is not possible without dismantling, so that the method can be easily carried out even in confined spaces.

[0032] In particular, an advantageous embodiment of the method consists in erecting a structure in the area of ​​the anchor arrangement prior to releasing the tension element, whereby access to the head section of the anchor is restricted or completely blocked. To release the anchor or the tension element, no direct access for a construction worker is necessary, since mandatory access to the head section is not mandatory.

[0033] According to a further development of the invention, it is also advantageous for the pressure relief device to be electrically operated, and for an electrical supply line to be laid from the pressure relief device to a remote control unit before or during construction of the structure. This supply line can thus also supply electrical energy from a remote control unit to the pressure relief device. The control unit can also be used to control the pressure relief device, in particular the current intensity, voltage, and / or operating time, etc.

[0034] This allows one or more anchors to be installed largely based on structural considerations and, in particular, without consideration of any adjacent structure. This allows for particularly economical and reliable support of an excavation wall, for example.

[0035] According to a preferred method variant, a heating device is used as the stress-relieving device, with which the tensile element is heated at the point of action to a softening temperature at which the tensile element is plastically deformed by the tensile stress. The material of the tensile element can be heated by several hundred degrees Celsius at the point of action, whereby the tensile strength of the material decreases. This can then cause plastic deformation in the region of the heated point of action. This heating can lead to melting of the material.

[0036] According to a further embodiment, it is advantageous to use a corrosion device as the stress relief device, with which the tensile element is specifically corroded at the point of action and the strength of the tensile element is reduced, so that the tensile element is plastically deformed by the tensile stress. The strength reduction occurs through electrochemical weakening and decomposition of the material of the tensile element at the point of action. Due to the strength reduction, the yield point of the preferably metallic material of the tensile element can be exceeded, so that elongation and plastic deformation can occur in the area of ​​the point of action. Over a longer period of time, the tensile element can also be completely severed due to the corrosion process and the applied tensile stress.

[0037] The invention will be explained in more detail below using a preferred embodiment, which is illustrated in the accompanying drawings. In the drawings: Fig. 1 is a schematic view of an anchor assembly according to the invention; Fig. 2 is an enlarged view of a head section of an anchor assembly according to the invention.

[0038] An anchor arrangement 10 according to the invention according to Figure 1 comprises an elongated anchor 12 with a tension element 14, which is inserted into a bore 7 in a soil 5. The anchor 12 serves to support and anchor back a retaining wall 3, which is designed to support an excavation pit 1 in the soil 5.

[0039] The tension element 14 of the anchor 12 comprises a base section 17, which can be anchored in the lower region of the borehole 7 in the ground 5 in a known manner by injecting a setting injection medium, such as cement mortar. A central section 18, which is essentially exposed in the borehole 7, extends from the base section 17 to a head section 20 in the region of the retaining wall 3. The head section 20 can absorb a compressive force exerted by the ground 5 on the retaining wall 3 and, via the tension element 14, divert it via the integrated base section 17 into a rear region of the ground 5, thus anchoring the retaining wall 3 back in the ground 5.

[0040] Within the excavation pit 1, a structure 9, indicated by a broken line, can be erected close to the head section 20. After erection of the structure 9, the anchor 12 must be released again, although access to the head section 20 of the anchor 12 through the structure is no longer possible or only very limited for a construction worker.

[0041] In Figure 2 In particular, a head portion 20 of an anchor 20 of an anchor assembly 10 according to the invention is shown in more detail. The anchor 12 with the tension element 14 extends through the support wall 3 into a bore 7 of an adjacent floor 5.

[0042] In the illustrated embodiment, the tension element 14 is formed with a plurality of tension members 16, each surrounded by a sheathing tube 19. At the free end of the tension element 14, a tensioning device 30 is formed with an anchor plate 32, which can be supported on an abutment surface on the supporting wall 3. The tension element 14 or the provided tension members 16 are connected to a tensioning head 34 of the tensioning device 30. For this purpose, the tensioning head 34 is formed with a plate-shaped wedge support 35 with conical receiving holes 36. Correspondingly designed tensioning cones 38 are received in the conical receiving holes 36, which are fastened to the free end of the respective tension members for applying a tensioning force. The tensioning device 30 can further comprise a cover cap 39 for covering the free ends of the tension members 16 and the tensioning head 34.

[0043] A receiving ring 50 can be interposed between the armature plate 32 and the clamping head 34, which can accommodate a stress-relieving device 40 in a receiving space. The stress-relieving device 40 can preferably be formed as a heating device with an induction coil 42. The stress-relieving device 40 can be supplied with electrical current via a supply line 44 from an operating unit spaced apart from the head section 20. By supplying electrical current, the stress-relieving device 40 can be activated, thus initiating stress-relieving of the armature 12.

[0044] The heating device can heat an adjacent point of action 24 on the tension element 14 in such a way that the tension element 14 or the tension members 16 are softened or melted to such an extent that the tensile stress in the tension element 14 necessary to support the retaining wall 3 during construction can be reduced and eliminated. The softening can cause plastic deformation of the tension element 14 to reduce the tensile stresses.

[0045] Additionally or alternatively, the stress relief device 40 can also be configured with a corrosion device with an electrode arrangement. The electrode arrangement, which can preferably be attached directly to the tension element 14, can generate an electrical current and an electrical voltage in the region of the exposure point 24 on the tension element 14. This can specifically trigger and accelerate corrosion of the exposure point 24. Additionally, a corrosion aid can also be arranged, particularly in the annular receiving space around the tension element 14. This can support and further accelerate the corrosion process.

Claims

1. Anchor assembly having an anchor (12), which is designed to be inserted into a drill hole (7) in the ground (5) and has an elongated traction element (14), which has - a base section (17) being designed for anchoring in the ground (5) by injecting an injection medium that can be set, - a centre section (18) designed to be arranged in the ground (5) together with the base section (17), and - a head portion (20), which is arranged outside of the hole (7) and a tensioning device (30) for applying a tensile stress, characterised in that - a tension release device (40) is arranged in the region of the head portion (20) and is designed for the targeted reduction of the strength of the traction element (14) at an effective point (24) to a reduced strength state, in which the traction element (14) is plastically deformed at the effective point (24) by the applied tensile stress in order to reduce the stress.

2. Anchor assembly according to claim 1, characterised in that when the anchor (12) is installed in the ground (5), the effective point (24) with the tension release device (40) is arranged outside the hole (7).

3. Anchor assembly according to claim 1 or 2, characterised in that the traction element (14) has two or more traction members (16).

4. Anchor assembly according to any one of claims 1 to 3, characterised in that the tension release device (40) is firmly or releasably attached to the head portion (20).

5. Anchor assembly according to any one of claims 1 to 4, characterised in that the tensioning device (30) comprises an anchor plate (32), which is supported relative to the ground (5) and has a passage (33) for the traction element (14), and comprises a tensioning head (34), to which the traction element (14) is fastened and which is supported on the anchor plate (32), wherein the traction element (14) can be braced relative to the anchor plate (32).

6. Anchor assembly according to claim 5, characterised in that the tension release device (40) and optionally a retaining ring (50) for the tension release device (40) are arranged between the anchor plate (32) and the tensioning head (34).

7. Anchor assembly according to any one of claims 1 to 6, characterised in that the tension release device (40) is designed as a heating device, in particular having at least one electrically operated induction coil (42), which is designed to heat the traction element (14), at least one traction member (16) at the effective point (24) to a softening temperature at which plastic deformation occurs.

8. Anchor assembly according to any one of claims 1 to 7, characterised in that the tension release device (40) is designed as a corrosion device having an electrode arrangement being designed to generate a corrosion voltage at the effective point (24).

9. Anchor assembly according to claim 8, characterised in that the corrosion device has at least one corrosion aid being arranged at the effective point (24) and comprises, in particular, a salt.

10. Anchor method, in which - an anchor (12) having an elongated traction element (14) is inserted into a drill hole (7) in the ground (5) and a foot portion (17) of the traction element (14) is anchored in the ground (5) by injecting a bonding injection medium, - tensile stress is applied to a head portion (20) of the traction element (14) outside the drill hole (7) by means of a tensioning device (30), and - finally, the tensile stress in the traction element (14) is relieved again, characterised in that - an anchor assembly (10) according to any one of claims 1 to 9 is formed, wherein a tension release device (40) is arranged in the region of the head portion (20) and a strength of the traction element (14) at an effective point (24) of the traction element (14) is reduced to a strength state, in which the traction element (14) is plastically deformed at the effective point (24) by the tensile stress, wherein the tensile stress in the traction element (14) is reduced.

11. Anchor method according to claim 10, characterised in that the released traction element (14) remains in the ground (5).

12. Anchor method according to claim 10 or 11, characterised in that a structure (9) is erected in the region of the anchor assembly (10) before the traction element (14) is released, wherein access to the head portion (20) of the anchor (12) is restricted or obstructed altogether.

13. Anchor method according to claim 12, characterised in that the tension release device (40) is electrically operated and in that an electrical supply line (44) to the tension release device (40) is laid from the tension release device (40) to a remote control unit before or during the constructing of the structure (9).

14. Anchor method according to any one of claims 10 to 13, characterised in that a heating device is used as the tension release device (40), with which the traction element (14) is heated at the effective point (24) to a softening temperature at which the traction element (14) is plastically deformed by the tensile stress.

15. Anchor method according to any one of claims 10 to 14, characterised in that a corrosion device is used as the tension release device (40), with which the traction element (14) is selectively corroded at the effective point (24) and a strength of the traction element (14) is reduced, so that the traction element (14) is plastically deformed by the tensile stress.