Prefabricated anchor head and anchor rod

Abstract

The utility model discloses a prefabricated anchor head which comprises a shell and an anchor disc, the shell comprises a barrel, the anchor disc is installed in the barrel, the two ends of the barrel in the axial direction form a head part and a tail part respectively, one end of a steel strand extends into the barrel from the tail part and is fixed to the anchor disc, an anchoring block is arranged in the shell, and the anchoring block is fixed to the head part of the steel strand. The anchor disc is fixed in the shell through an anchoring block, and the anchoring block is formed by any one or two of pure cement paste, cement mortar or concrete. The utility model further discloses an anchor rod adopting the prefabricated anchor head. The anchor disc is pre-buried in the anchoring block to form the prefabricated anchor head, so that the conditions such as forming temperature and pressure of the anchoring block can be conveniently controlled, batch production can be performed, the production efficiency is improved, the quality of the anchoring block can be checked, the quality of the prefabricated anchor head is ensured, and the situation that the anchor head is damaged due to the tension of a steel strand is avoided. And therefore, the quality of the anchor rod is ensured, and the service life of the anchor rod is prolonged.

Description

Technical Field

[0001] The utility model relates to a prefabricated anchor head and an anchor rod. Background Art

[0002] In the anchor rod using steel strand as the rod body, in order to improve the stability of the steel strand underground, it is necessary to install an anchor plate on the end of the anchor cable located underground. The anchor plate is wrapped in an anchor body formed by cement slurry. As the main load-bearing member, the anchor plate bears the external tension transmitted by the steel strand. During the grouting process, the soil above the anchor hole falls, grouting voids, and grouting pressure fluctuations will cause defects in the anchor body. These defects will expand and gradually expand to the entire cross-section of the anchor body when the anchor rod is subjected to external tension, especially in the area where the anchor plate is located. In severe cases, cracks will occur in the anchor body, and external water will enter the anchor rod along the cracks, corroding the steel strand and reducing the tensile strength of the anchor rod.

[0003] Therefore, how to ensure the integrity of the anchor body wrapped around the anchor plate, avoid cracks or even breakage of the anchor body at the anchor plate, and maintain the tensile strength of the anchor rod is still an issue that needs to be further studied for steel strand anchor rods. Utility Model Content

[0004] In order to solve the problem in the prior art that the anchor body is cracked due to the fluctuations generated during the grouting process, thereby reducing the tensile strength of the anchor rod, the present application first proposes a prefabricated anchor head, which includes an outer shell and an anchor plate. The outer shell includes a cylinder, and an anchor plate is installed in the cylinder. The two ends of the cylinder in the axial direction are respectively formed as a head and a tail. One end of the steel strand extends into the cylinder from the tail and is fixed to the anchor plate. An anchor block is arranged in the outer shell, and the anchor plate is fixed in the outer shell by the anchor block. The anchor block is formed by any one or two of pure cement slurry, cement mortar or concrete.

[0005] In the present application, the anchor plate is embedded in the anchor block to form a prefabricated anchor head. When manufacturing the prefabricated anchor head, not only can the formation temperature, pressure and other conditions of the anchor block be conveniently controlled, but also batch production can be carried out to improve production efficiency. When manufacturing the prefabricated anchor head, the internal quality of the anchor block can be inspected by ultrasonic or X-ray methods to ensure the quality of the prefabricated anchor head, thereby avoiding the phenomenon that the anchor body is prone to cracks or even breaks at the anchor plate due to the tension of the steel strand, thereby ensuring the quality and service life of the anchor rod.

[0006] Furthermore, in order to facilitate the fixing of the anchor plate, a pressure plate is fixedly arranged in the middle part of the cylinder in the axial direction, and the anchor plate is located on the side of the pressure plate facing the head, and the anchor plate abuts against the pressure plate. This design does not require the anchor plate to be fixed to the shell, thereby avoiding deformation of the anchor hole on the anchor plate due to welding, which affects the installation of the steel strand.

[0007] Furthermore, the shell also includes an end plate, which is welded to the tail of the cylinder. The end plate can effectively seal the outside of the cylinder, making it easy to inject pure cement slurry, cement mortar or concrete into the shell.

[0008] Furthermore, for easy installation, the housing further comprises a conical guide cone, the guide cone being located at the head of the cylinder, and the small end of the guide cone extending in a direction away from the tail. The guide cone can effectively avoid deviation from the preset position when installing the steel strand.

[0009] Furthermore, a sheath tube is provided on the steel strand, and one end of the sheath tube is sealedly inserted into the anchor block. This design can effectively seal one end of the sheath tube in the anchor hole, preventing water in the anchor hole from entering the sheath tube when installing the anchor rod, thereby corroding the steel strand.

[0010] Furthermore, in order to facilitate the injection of pure cement slurry, cement mortar or concrete into the shell, a grouting hole is provided on the shell.

[0011] Secondly, the present application also provides an anchor rod, which includes a rod body and an anchor body wrapped outside the rod body, the rod body includes a steel strand and a prefabricated anchor head as described above and installed at one end of the steel strand, the rod body is divided into an anchoring section, a free section and a tensioning section, and the prefabricated anchor head is installed at the end of the anchoring section; a casing tube is sleeved on the steel strand, one end of the casing tube is sealingly inserted into the anchor block, and the other end of the casing tube extends outward from the anchor rod hole, the anchor body is wrapped outside the casing tube, and the anchor body extends from the anchoring section to the free section, and at least a portion of the casing tube located in the free section is wrapped in the anchor body.

[0012] After using the prefabricated anchor head, since the anchor plate is pre-buried in the anchor block of the prefabricated anchor head, the overall strength of the prefabricated anchor head is improved. During the tensioning of the steel strand and subsequent use, the cracking of the prefabricated anchor head can be avoided, thereby ensuring the use of the anchor rod.

[0013] At present, the anchor body is only located in the anchoring section and does not extend to the free section to ensure that the free section can deform freely during the tensioning process of the steel strand. Since the steel strands in the free section area are also wrapped in the sheath tube in this application, the isolation effect of the sheath tube is utilized to avoid the adhesion of the anchor body to the steel strands in the free section area, which can ensure that the steel strands in the free section can deform freely during the tensioning process. Since in this application, the anchor body is extended to the free section, the length of the anchor body is increased, and the bonding area between the anchor body and the external soil is increased, thereby increasing the tensile strength of the anchor rod and being able to apply greater tension to the steel strand.

[0014] Furthermore, in order to maximize the bonding area between the anchor body and the external soil, the jacket pipe located in the free section is completely wrapped in the anchor body.

[0015] Furthermore, in order to improve the stability of the anchor rod underground, an enlarged head is provided in the anchor body in the anchoring section area, and the prefabricated anchor head is located in the enlarged head.

[0016] Furthermore, a push rod is installed on the prefabricated anchor head, which extends toward the tensioning section of the anchor rod and exceeds the end face of the prefabricated anchor head facing the tensioning section. The push rod can be inserted into the bolt hole of the end flange of the drill rod to insert the steel strand into the anchor rod hole using the drill rod.

[0017] Currently, when inserting a rod body made of steel strands into an anchor hole, a drill bit is inserted into the inner grouting hole at the center of the anchor plate, and then the drill bit is used to push the anchor plate to insert the rod body into the anchor hole. However, in the present application, a prefabricated anchor head is installed on the rod body, and the anchor plate is wrapped in an anchor block, so the rod body cannot be inserted into the anchor hole in the above manner.

[0018] In order to overcome the above problems, in the present application, two push rods made of steel bars are installed on the prefabricated anchor head, and the installation positions of the two push rods are set to be able to be inserted into the bolt holes of the end flange of the drill rod. The connecting flange of the drill bit can be installed on the drill rod through the end flange. After the drilling of the anchor hole is completed, the drill bit is removed from the drill rod, and then the push rods are inserted into the bolt holes of the end flange, and the rod body is inserted into the anchor hole using the drill rod.

[0019] The design enables the steel strand to be inserted into the anchor hole by still using a drill rod without the need to set up other special tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of an embodiment of a prefabricated anchor head.

[0021] Figure 2 yes Figure 1 Top view of the .

[0022] Figure 3 yes Figure 1 Center AA view.

[0023] Figure 4 It is a structural schematic diagram of an embodiment of an anchor rod.

[0024] Figure 5 yes Figure 4 Enlarged view in the middle BB direction. DETAILED DESCRIPTION

[0025] In the drawings, the extending direction of the first axis X is referred to as the first axis direction.

[0026] Example 1

[0027] The structure of the prefabricated anchor head 10 is first described below. Figure 1-Figure 3 The prefabricated anchor head 10 includes a shell 101 and an anchor plate 21. In this embodiment, the shell is a metal part, specifically in this embodiment, the shell is a steel part, and specifically includes a cylinder 12 extending along the first axial direction, that is, the axial direction of the cylinder extends along the first axial direction. For the convenience of description, the two ends of the axial direction of the cylinder are respectively referred to as the head 121 and the tail 122. The shell also includes a guide cone 11 welded to the head 121 and an end plate 14 welded to the tail 122. The guide cone is conical, and the small end of the guide cone extends in the direction away from the tail. The guide cone has an outer peripheral surface in the shape of a right circular cone.

[0028] A pressure plate 13 is welded to the middle part of the cylinder 12 in the axial direction, and the anchor plate 21 is located on the side of the pressure plate 13 facing the head, and the anchor plate abuts against the pressure plate. One end of the steel strand 31 freely passes through the end plate and the pressure plate and is fixed on the anchor plate. Specifically in this embodiment, the anchor plate adopts a multi-porous clip-type anchor, and the clip 212 of the multi-porous clip-type anchor is clamped on the end of the steel strand 31. An external grouting hole 36 is opened on the end plate, that is, a grouting hole is opened on the outer shell.

[0029] An anchor block is provided in the shell, and the anchor plate is fixed in the shell by the anchor block. The anchor block is not shown in the drawings. In this embodiment, the anchor block is formed by pure cement slurry poured in the shell. It can be understood that in other embodiments, the anchor block can also be formed by cement mortar or concrete poured in the shell, or by two of pure cement slurry, cement mortar or concrete forming different blocks and bonding the blocks together.

[0030] When making the prefabricated anchor head in this embodiment, the pressure plate is first welded into the cylinder, and then one end of the steel strand is passed through the anchor cable hole 141 on the end plate and the cable hole 132 on the pressure plate in sequence and fixed to the anchor plate, and then the guide cone and the end plate are welded to the cylinder to complete the production of the shell. The pressure plate divides the inner cavity of the shell into a first chamber 102 and a second chamber 103, wherein the first chamber is located between the pressure plate and the end plate, and the second chamber is located between the pressure plate and the guide cone. To facilitate grouting, a middle grouting hole 131 is provided on the pressure plate, and an inner grouting hole 211 is provided on the anchor plate. Pure cement slurry is injected into the first chamber 102 through the outer grouting hole, and the pure cement slurry enters the second chamber 103 along the middle grouting hole and the inner grouting hole, and the inner cavity of the entire shell is filled with pure cement slurry. The grouting pressure is 20-35MPa. In this embodiment, the grouting pressure is specifically 25MPa. It is understood that in other embodiments, the grouting pressure may be 20 MPa, 30 MPa or 35 MPa, and of course may be other pressure values ​​between 20 and 35 MPa. The pure cement slurry forms an anchor block after solidification. When the pure cement slurry is injected into the housing, the steel strand needs to be tensioned so that the clips on the porous clip anchor can clamp the steel strand.

[0031] When the anchor block is formed by cement mortar or concrete, due to the poor fluidity of cement mortar and concrete, it is necessary to open a grouting hole connected to the second chamber 103 on the cylinder or the guide cone, or to open a grouting hole connected to the second chamber 103 on both the cylinder and the guide cone, and it is also possible to open a grouting hole connected to the first chamber 102 on the cylinder at the same time or only on the cylinder.

[0032] It is understandable that different types of slurries can also be poured into the first chamber and the second chamber, for example, concrete can be poured into the first chamber and cement mortar or pure cement slurry can be poured into the second chamber, or cement mortar can be poured into the first chamber and concrete or pure cement slurry can be poured into the second chamber. Since pure cement slurry has good fluidity, pure cement slurry is preferably poured into the second chamber so that the pure cement slurry can form a dense wrapping structure for the clip. When the slurries are poured into the second chamber and the second chamber respectively, the middle grouting hole 131 on the pressure plate and the inner grouting hole 211 on the anchor plate can be eliminated.

[0033] In this embodiment, a sheath tube 32 is sleeved on the steel strand, and one end of the sheath tube is sealed and inserted into the anchor block. Before pouring into the first chamber, the sheath tube 32 needs to be inserted into the anchor hole 141 on the end plate and extended into the first chamber, so that the pure cement slurry can seal and wrap the end of the sheath tube extending into the first chamber, so that one end of the sheath tube is sealed and inserted into the anchor block.

[0034] Example 2

[0035] The structure of the anchor rod 20 is described below. Figure 1-Figure 5 The anchor rod extends along the first axis direction, and includes a rod body and a prefabricated anchor head 10 installed at one end of the rod body. The rod body is divided into an anchoring section 42, a free section 43 and a tensioning section 44. The prefabricated anchor head 10 is installed at the end of the anchoring section. The sheath tube 32 is sleeved on the steel strand. One end of the sheath tube is sealed and inserted into the anchor block. The other end of the sheath tube extends outward from the anchor hole 60. The anchor body 46 is wrapped outside the sheath tube. The anchor body extends from the anchoring section to the free section, and the sheath tube located in the free section is completely wrapped in the anchor body. That is, the anchor body extends from the anchoring section to the free section, and the sheath tube located in the free section is completely wrapped in the anchor body.

[0036] It is understood that in another embodiment, only a portion of the sheath tube located in the free section facing the anchoring section may be wrapped in the anchor body. In this embodiment, the sheath tube 32 is specifically an anti-corrosion metal bellows.

[0037] An enlarged head 41 is provided in the anchor body 46 in the anchoring section region, and the prefabricated anchor head 10 is located in the enlarged head 41. The enlarged head is part of the anchor body and is described for convenience.

[0038] The anchor body in the free segment area is called a free segment anchor body, and the anchor body located between the enlarged head and the free segment anchor body is called an ordinary anchor body. In the accompanying drawings, S1 represents the first length range of the enlarged head, S2 represents the second length range of the ordinary anchor body, S3 represents the third length range of the free segment anchor body, and S4 represents the fourth length range of the tensioning segment.

[0039] The first diameter D1 of the enlarged head is greater than the second diameter D2 of the common anchor body, and the second diameter D2 of the common anchor body is greater than the third diameter D3 of the free segment anchor body. Specifically in this embodiment, the first diameter D1 of the enlarged head is 600 mm, the second diameter D2 of the common anchor body is 400 mm, and the third diameter D3 of the free segment anchor body is 250 mm.

[0040] In the area corresponding to the anchoring section 42 in the jacket pipe, there is a bonding body 34 formed by pure cement slurry, and in the area corresponding to the free section 43 in the jacket pipe, there is filled with lubricating grease. In this embodiment, the lubricating grease specifically adopts anti-corrosion lubricating grease for non-bonded prestressed tendons. Pure cement slurry is used to make the steel strand bonded to the jacket pipe, and the jacket pipe and the anchor body are formed into a whole, ensuring that the steel strand can be stably maintained in the underground soil during the tensioning process of the steel strand. The steel strand in the free section area is protected by lubricating grease.

[0041] At present, when inserting the rod body formed by the steel strand into the anchor hole, a drill bit is inserted into the inner grouting hole at the center of the anchor plate, and then the drill bit is used to push the anchor plate to insert the rod body into the anchor hole. However, in the present application, a prefabricated anchor head is installed on the rod body, and the anchor plate is wrapped in the anchor block, so the rod body cannot be inserted into the anchor hole in the above manner.

[0042] In order to overcome the above problems, in this embodiment, two push rods 17 made of steel bars are installed on the prefabricated anchor head, and the installation positions of the two push rods are set to be able to be inserted into the bolt holes of the end flange of the drill rod. The connecting flange of the drill bit can be installed on the drill rod through the end flange. After the drilling of the anchor hole is completed, the drill bit is removed from the drill rod, and then the push rods are inserted into the bolt holes of the end flange, and the rod body is inserted into the anchor hole using the drill rod.

[0043] See also Figure 2 In order to minimize the deviation of the drill rod and the prefabricated anchor head on the axis, the casing pipe needs to be bent to reduce the deviation of the drill rod and the prefabricated anchor head on the axis. The casing pipe made of anti-corrosion metal bellows can bend the rod body and smoothly restore the preset position after the rod body reaches the set position in the anchor hole.

[0044] In order to facilitate the injection of pure cement slurry and lubricating grease into the sheath pipe, an inner grouting pipe 33 is pre-installed in the anti-corrosion metal bellows. After the steel strand is inserted into the set position of the anchor hole, the inner grouting pipe is used to inject pure cement slurry and lubricating grease into the anti-corrosion metal bellows in sequence. During the process of injecting pure cement slurry and lubricating grease into the anti-corrosion metal bellows, the inner grouting pipe is simultaneously pulled outward. After the injection of lubricating grease is completed, the inner grouting pipe is completely pulled out of the anti-corrosion metal bellows.

[0045] When the anchor is inserted into the anchor hole, the outer grouting pipe located outside the sheath pipe is also inserted into the anchor hole. After the pure cement slurry and lubricating grease in the anti-corrosion metal bellows are injected, the pure cement slurry is injected into the anchor hole by the outer grouting pipe to form an anchor body 46. After the anchor body reaches the curing time, the steel strand is tensioned and fixed by the steel strand anchor 45 to complete the construction of the anchor. It is understood that cement mortar can also be injected into the anchor hole through the outer grouting pipe.

Claims

1. A prefabricated anchor head, characterized in that: It includes an outer shell and an anchor plate. The outer shell includes a cylinder. An anchor plate is installed in the cylinder. The two ends of the cylinder in the axial direction are respectively formed as a head and a tail. One end of the steel strand extends into the cylinder from the tail and is fixed on the anchor plate. An anchor block is arranged in the outer shell. The anchor plate is fixed in the outer shell by the anchor block. The anchor block is formed by any one of pure cement slurry, cement mortar or concrete.

2. The prefabricated anchor head according to claim 1, characterized in that: A pressure plate is fixedly arranged at the middle part of the cylinder in the axial direction, the anchor plate is located at the side of the pressure plate facing the head, and the anchor plate is against the pressure plate.

3. The prefabricated anchor head according to claim 1, characterized in that: The shell also includes an end plate, which is welded to the tail of the cylinder.

4. The prefabricated anchor head according to claim 1, characterized in that: The shell also includes a conical guide cone, which is located at the head of the cylinder, and the small end of the guide cone extends in a direction away from the tail.

5. The prefabricated anchor head according to claim 1, characterized in that: A sheath tube is sleeved on the steel strand, and one end of the sheath tube is sealingly inserted into the anchor block.

6. The prefabricated anchor head according to any one of claims 1 to 5, characterized in that: Grouting holes are arranged on the shell.

7. An anchor rod, characterized in that: The invention comprises a rod body and an anchor body wrapped outside the rod body, wherein the rod body comprises a steel strand and a prefabricated anchor head according to any one of claims 1 to 6 installed at one end of the steel strand, the rod body is divided into an anchoring section, a free section and a tensioning section, and the prefabricated anchor head is installed at the end of the anchoring section; The sheath tube is sleeved on the steel strand, one end of the sheath tube is sealingly inserted into the anchor block, the other end of the sheath tube extends outward from the anchor hole, the anchor body is wrapped outside the sheath tube, and the anchor body extends from the anchor section to the free section, and at least part of the sheath tube located in the free section is wrapped in the anchor body.

8. The anchor rod according to claim 7, characterized in that: The sheath tube located in the free section is completely wrapped in the anchor body.

9. The anchor rod according to claim 7, characterized in that: An enlarged head is arranged in the anchor body in the region of the anchoring section, and the prefabricated anchor head is located in the enlarged head.

10. The anchor rod according to claim 7, characterized in that: A push rod is installed on the prefabricated anchor head, which extends toward the tensioning section of the anchor rod and exceeds the end face of the prefabricated anchor head facing the tensioning section. The push rod can be inserted into the bolt hole of the end flange of the drill rod to insert the steel strand into the anchor rod hole using the drill rod.

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