Prestressed steel strand anchor rod and construction method thereof

Abstract

This invention provides a prestressed steel strand anchor rod and its construction method. The prestressed steel strand anchor rod includes a rod body and prestressed steel strands, each prestressed steel strand having multiple anchor cables. The invention is characterized by further including a first bearing plate, a second bearing plate, a wedge anchor, a support plate, and a compression anchor. The multiple anchor cables of the prestressed steel strand pass through the first bearing plate and are tensioned at the first bearing plate. The wedge anchor locks the tensioned prestressed steel strands at the upper end of the first bearing plate. The multiple anchor cables pass through the support plate and are then sequentially fitted with the second bearing plate and the compression anchor. The support plate is positioned above the wedge anchor using the rebound force of the anchor cables. This invention uses two anchors: the first anchor locks the prestress, and the second anchor prevents the bearing plate from falling off. It fully utilizes the advantages of the wedge anchor and the compression anchor, allowing for better implementation of anchor rod construction before the base plate.

Description

Technical Field

[0001] This invention relates to the field of anti-buoyancy technology for basements, and more particularly to a prestressed steel strand anchor rod and its construction method. Background Technology

[0002] Most basements have buoyancy issues. According to the "Technical Standard for Buoyancy Resistance of Building Engineering" JGJ476-2019, projects with a buoyancy resistance design level of A should be designed to prevent cracking and use prestressed anchor rods.

[0003] a. If the ordinary post-tensioned prestressing process is adopted, and the basement slab is used as the tensioning end after the basement slab is completed, the following problems will occur: tensioning can only be carried out after the basement slab is completed and reaches the corresponding strength, which will affect the construction progress.

[0004] b. The above-mentioned traditional prestressed steel strands require the pre-reservation of tensioning channels on the base plate, which results in a tensioning hole being generated at the corresponding position of each anti-buoyancy anchor rod on the structural base plate, posing a risk of water seepage.

[0005] Existing patents, such as the anti-buoyancy anchor bolt and its construction method disclosed in patent publication number CN112575823A, have the following drawbacks in their anchor bolt structure:

[0006] (i) The upper section of the anchor rod is equipped with a sleeve as a free section, and the lower section uses the grout wrapping force to anchor the prestressed cable. It is a "tension type" prestressed anchor rod, which cannot completely guarantee that the anchoring section will not crack.

[0007] (ii) The anchoring end of the anchor bolt adopts the form of a steel force transmission cylinder. The steel force transmission cylinder is installed at the top of the hole, and prestress is applied and locked at the top of the steel force transmission cylinder. Due to the fact that the force transmission cylinder is an important pressure-bearing component, it is required to have high strength and load-bearing capacity, and therefore the cost is also relatively high;

[0008] (iii) Steel force transmission cylinders need to be cut and welded from steel profiles, which is a complex process. Force transmission cylinders of different heights also need to be shaped and processed separately.

[0009] (iv) Since the height of the steel force transmission cylinder is a fixed value, the requirements for the anchor bolt hole elevation are very strict. Especially when the anchor bolt hole elevation is lower than the design, it is almost impossible to install. It is necessary to extend the rod body or customize the extended force transmission component, which results in higher costs.

[0010] (v) A steel force transmission cylinder is used, which requires an opening in the middle to make the concrete inside the force transmission cylinder dense. In addition, the construction density cannot be guaranteed. Summary of the Invention

[0011] The purpose of this invention is to provide a prestressed steel strand anchor rod and its construction method to solve the above-mentioned problems of steel force transmission cylinders.

[0012] The technical solution of the present invention is as follows: a prestressed steel strand anchor rod includes a rod body and prestressed steel strands arranged in the rod body along the length direction of the rod body. The prestressed steel strands have multiple anchor cables. The invention is characterized by further including a first bearing plate, a second bearing plate, a wedge anchor, a support plate, and a compression anchor. The multiple anchor cables of the prestressed steel strands pass through the first bearing plate and are tensioned at the first bearing plate. The wedge anchor locks the tensioned prestressed steel strands at the upper end of the first bearing plate. After passing through the support plate, the multiple anchor cables are sequentially fitted with the second bearing plate and the compression anchor. The support plate is positioned above the wedge anchor using the rebound force of the anchor cables.

[0013] In the above solution, the design of the supporting plate has the following advantages compared to a steel force transmission cylinder:

[0014] a. It can achieve the goal of holding the second pressure plate up without moving down by relying solely on the clamping force, without transmitting pressure, without requiring pressure bearing capacity, and the amount of steel used is significantly lower than that of a steel force transmission cylinder.

[0015] b. The support plate can be made of thin steel plate by stamping or laser cutting, which is simple to manufacture and convenient to transport.

[0016] c. When there is an error in the elevation of the borehole, a support plate can be directly installed on the upper part of the borehole to overcome it, which greatly reduces the construction accuracy requirements for the borehole elevation and makes it more tolerant of errors.

[0017] d. Support plate is used for support, and there is no sealed space at the anchoring end, so there is no problem with concrete density.

[0018] Preferably, the support plate has n clamping arms, where n = the number of anchor cables, and the included angle between every two clamping arms is 360° / n. Each clamping arm has a clamping hole for the anchor cable to pass through.

[0019] The aforementioned structure of the supporting plate allows the anchor cables and the second bearing plate on each anchor cable to be evenly arranged around the center of the hole in the basement floor slab, so that the concrete is evenly stressed and meets the requirements for punching shear and local pressure bearing capacity.

[0020] Preferably, the locking hole is an oblong hole. The normally vertical anchor cable (the anchor cable that needs to be extended) is pulled open and locked into the inside of the oblong hole, secured by the anchor cable's own elasticity. The partially outward-sloping anchor cable (the anchor cable that needs to be retracted) is retracted and locked into the outside of the oblong hole, secured by the anchor cable's own tension. The secured support plate prevents the second bearing plate from sliding down, ensuring that the second bearing plate is at the design elevation.

[0021] Preferably, one end of the clamping hole has an opening, and the openings on all n clamping arms face the same direction of rotation. This open-aperture design can be implemented after the compression anchor 7 is installed.

[0022] Preferably, the end of the opening furthest from the locking hole is a flared opening. This facilitates the insertion of the anchor cable and prevents it from easily coming out.

[0023] Preferably, the prestressed steel strand anchor also includes a PVC sleeve, which is fitted onto the prestressed steel strand and located at the end of the first bearing plate away from the wedge anchor.

[0024] Preferably, the lower end of the first bearing plate is provided with a spiral steel bar, which is fitted onto the prestressed steel strand.

[0025] Preferably, the prestressed steel strand anchor rod further includes a third bearing plate, a limiting plate, and a guide cap. The anchor bars of the prestressed steel strands located at the lower end of the rod pass through the third bearing plate and are locked by the compression anchor. The limiting plate is fixed at the lower end of the compression anchor, and the guide cap is located at the lower end of the third bearing plate.

[0026] Preferably, the upper end of the third bearing plate is provided with a spiral steel bar, which is sleeved on the prestressed steel strand.

[0027] The present invention also provides a construction method for the above-mentioned prestressed steel strand anchor rod, comprising the following steps:

[0028] 1) Construct the prestressed steel strand anchor rod in the stratum below the basement chassis area, and extend the prestressed steel strand to be tensioned end in the rod body of the prestressed steel strand anchor rod into the chassis area;

[0029] 2) A first bearing plate is installed at the top of the rod, and the first bearing plate is located at the top of the hole in the basement floor area;

[0030] 3) The anchor cable is tensioned at the first bearing plate and locked with a wedge anchor to generate prestress inside the anchor rod, forming the first anchor to provide prestress for the anchor rod;

[0031] 4) Install a support plate at the upper end of the anchor cable, and use the rebound force of the anchor cable to hold the support plate in place, while simultaneously using the support plate to separate the anchor cables one by one.

[0032] 5) Install a second bearing plate 4 on each of the separate anchor cables;

[0033] 6) Install a compression anchor on the anchor cable, the compression anchor being located above the second bearing plate, and use the second bearing plate to anchor the anchor rod into the bottom plate area to form a second anchor.

[0034] 7) A concrete mixture is poured in the basement area to form the basement basement slab, thereby fixing the prestressed steel strand anchor rods in the basement basement basement slab.

[0035] Compared with related technologies, the beneficial effects of the present invention are as follows:

[0036] 1. Two anchorages are installed. The first anchorage locks the prestress, and the second anchorage prevents the bearing plate from falling off. This fully utilizes the advantages of wedge anchors and squeeze anchors, and can better realize the construction of anchor rods before the base plate.

[0037] Second, it adopts prestressed steel strands with self-rubber coating and a load-bearing body (third bearing plate and extrusion anchor) at the bottom. Therefore, the entire length is a free section, which is a "pressure type" prestressed anchor rod, which can strictly ensure that the anchor rod will not crack.

[0038] Third, the support plate only relies on clamping force to hold the pressure plate upward and prevent it from moving downward. It does not transmit pressure and does not need to bear pressure. The amount of steel used in a single support plate is less than 5% of that used in steel force transmission cylinders.

[0039] 4. When there is an error in the elevation of the opening in the basement floor slab, a support plate can be directly installed at the designed elevation above the opening, which greatly reduces the construction accuracy requirements for the opening elevation and makes it more tolerant of errors. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the prestressed steel strand anchor provided by the present invention;

[0041] Figure 2 This is a schematic diagram of the anchoring device in the base plate area.

[0042] Figure 3 A schematic diagram of the structure supporting the card plate in the first embodiment;

[0043] Figure 4 A schematic diagram of the structure supporting the card plate in the second embodiment;

[0044] Figure 5 A schematic diagram of the structure supporting the card plate in the third embodiment.

[0045] In the attached diagram: 1. Rod body; 2. Prestressed steel strand; 21. Anchor cable; 3. First bearing plate; 4. Second bearing plate; 5. Wedge anchor; 6. Support plate; 61. Clamping arm; 62. Clamping hole; 63. Opening; 7. Extrusion anchor; 8. PVC sleeve; 9. Spiral steel bar; 10. Third bearing plate; 11. Limiting plate; 12. Guide cap; 13. Base plate area. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0047] like Figure 1 , Figure 2 As shown, this embodiment provides a prestressed steel strand anchor rod comprising a rod body 1, prestressed steel strands 2, a first bearing plate 3, a second bearing plate 4, a wedge anchor 5, a support plate 6, a compression anchor 7, a PVC sleeve 8, spiral reinforcing bars 9, a third bearing plate 10, a limiting plate 11, and a guide cap 12. The first bearing plate 3, the second bearing plate 4, the wedge anchor 5, the support plate 6, the compression anchor 7, and the PVC sleeve 8 form an anchoring device.

[0048] The prestressed steel strand 2 is laid out along the length of the pole 1 and within the pole 1. The prestressed steel strand 2 has multiple anchor cables 21.

[0049] The prestressed steel strand 2 has multiple anchor cables 21 that pass through the first pressure plate 3 and are tensioned at the first pressure plate 3. The wedge anchor 5 locks the tensioned prestressed steel strand 2 at the upper end of the first pressure plate 3. The wedge anchor 5 can be an externally purchased component. The multiple anchor cables 21 pass through the support plate 6 and are then sequentially fitted with the second pressure plate 4 and the compression anchor 7. The support plate 6 is positioned above the wedge anchor 5 using the rebound force of the anchor cables 21. The wedge anchor 5 and the compression anchor 7 can be externally purchased components.

[0050] like Figures 3-5 As shown, the support plate 6 has n clamping arms 61, where n = the number of anchor cables, and the included angle between any two clamping arms 61 is 360° / n. Figure 3 As shown, n=2, as Figure 4 As shown, n=3, as Figure 5 As shown, n=4. Each of the clamping arms 61 is provided with a clamping hole 62 for the anchor cable 21 to pass through. The clamping hole 62 is an elongated hole. And one end of the clamping hole 62 is provided with an opening 63, and the openings 63 on the n clamping arms 61 all face the same direction of rotation (such as all opening in the direction of counterclockwise rotation, or all opening in the direction of clockwise rotation). The end of the opening 63 away from the clamping hole 62 is a flared mouth.

[0051] like Figure 2 As shown, the PVC sleeve 8 is fitted onto the prestressed steel strand 2 and is located at the end of the first bearing plate 3 away from the wedge anchor 5.

[0052] The lower end of the first pressure plate 3 is provided with a spiral steel bar 9, which is fitted onto the prestressed steel strand 2.

[0053] like Figure 1As shown, the anchor bars of the prestressed steel strands 2 located at the lower end of the rod 1 pass through the third bearing plate 10 and are locked by the compression anchor 7. The lower end of the compression anchor 7 is fixed with the limiting plate 11, and the guide cap 12 is located at the lower end of the third bearing plate 10. A grouting pipe is installed inside the anchor rod, passing through the first bearing plate 3, the third bearing plate 10 and the limiting plate 11 from bottom to top, and extending into the guide cap 12.

[0054] The construction method for prestressed steel strand anchor bolts provided by this invention is as follows:

[0055] Step S1: Construct the prestressed steel strand anchor rod in the stratum below the basement floor area 13, and extend the prestressed steel strand 2 to be tensioned end in the rod body 1 of the prestressed steel strand anchor rod into the floor area 13.

[0056] Step S2: A first bearing plate 3 is installed at the top of the rod 1. The first bearing plate 3 is located at the top of the hole in the basement floor area 13. If necessary, a spiral steel bar 9 for resisting local pressure is installed. A pre-drilled hole is provided on the first bearing plate 3 to facilitate the passage of the anchor cable 21 of the prestressed steel strand 2. The position of the pre-drilled hole is aligned with the hole of the wedge anchor 5.

[0057] Step S3: After reaching a certain strength, the anchor cable is tensioned at the first bearing plate 3 and locked with the wedge anchor 5 to generate prestress inside the anchor rod; thus forming the first anchor to provide prestress for the anchor rod.

[0058] Step S4: Install a support plate 6 and a second pressure plate 4 at the upper end of the anchor cable 21. The support plate 6 is installed one-to-one with the anchor cable. The support plate 6 is held in place by the rebound force of the anchor cable 21, reliably supporting the upper second pressure plate 4 to the design elevation. At the same time, it separates the anchor cables 21 to prevent the second pressure plates 4 connected to the anchor cables 21 from overlapping. A second pressure plate 4 is installed on each separated anchor cable 21, thereby improving the punching shear resistance and local pressure bearing capacity.

[0059] Step S5: Install the compression anchor 7 above the second pressure plate 4, and use the second pressure plate 4 to reliably anchor the anchor rod into the bottom plate area 13, thereby forming the second anchor.

[0060] Step S6: For anchor cables 21 that cannot be secured, thin iron wire can be used to wrap around the anchor cables 21 and tie them in place to ensure that the second bearing plate 4 is at the design elevation.

[0061] Step S7 involves pouring concrete mixture into the basement slab area 13 to form the basement floor slab, thus fixing the prestressed steel strand anchor rods into the basement floor slab. This ensures durability and does not affect the use of the basement.

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A prestressed steel strand anchor rod, characterized in that, The device includes a rod body and prestressed steel strands laid within the rod body along its length. Each prestressed steel strand has multiple anchor cables. The device further includes a first pressure plate, a second pressure plate, a wedge anchor, a support plate, and a compression anchor. The multiple anchor cables of the prestressed steel strand pass through the first pressure plate and are tensioned at the first pressure plate. The wedge anchor locks the tensioned prestressed steel strands at the upper end of the first pressure plate. After passing through the support plate, the multiple anchor cables are sequentially fitted with the second pressure plate and the compression anchor. The support plate is positioned above the wedge anchor using the rebound force of the anchor cables. The support plate has n clamping arms, where n = the number of anchor cables, and the included angle between every two clamping arms is 360° / n. Each clamping arm has a clamping hole for the anchor cable to pass through. One end of the clamping hole has an opening, and the openings on all n clamping arms face the same direction of rotation.

2. The prestressed steel strand anchor bolt according to claim 1, characterized in that, The card hole is an oblong hole.

3. The prestressed steel strand anchor bolt according to claim 1, characterized in that, The end of the opening away from the card hole is a flared opening.

4. The prestressed steel strand anchor bolt according to claim 1, characterized in that, It also includes a PVC sleeve, which is fitted onto the prestressed steel strand and located at the end of the first bearing plate away from the wedge anchor.

5. The prestressed steel strand anchor bolt according to claim 1, characterized in that, The lower end of the first bearing plate is provided with a spiral steel bar, which is fitted onto a prestressed steel strand.

6. The prestressed steel strand anchor bolt according to claim 1, characterized in that, It also includes a third pressure plate, a limiting plate, and a guide cap. The anchor bars of the prestressed steel strands located at the lower end of the rod pass through the third pressure plate and are locked by the compression anchor. The limiting plate is fixed at the lower end of the compression anchor, and the guide cap is located at the lower end of the third pressure plate.

7. The prestressed steel strand anchor bolt according to claim 6, characterized in that, The upper end of the third bearing plate is provided with a spiral steel bar, which is sleeved on the prestressed steel strand.

8. A construction method for a prestressed steel strand anchor as described in any one of claims 1 to 7, characterized in that, Includes the following steps: 1) Construct the prestressed steel strand anchor rod in the stratum below the area used to construct the basement floor slab, and extend the prestressed steel strand to be tensioned end of the prestressed steel strand in the rod body of the prestressed steel strand anchor rod to the floor slab area; 2) A first bearing plate is installed at the top of the rod, and the first bearing plate is located at the top of the hole in the basement floor area; 3) The anchor cable is tensioned at the first bearing plate and locked with a wedge anchor to generate prestress inside the anchor rod, forming the first anchor to provide prestress for the anchor rod; 4) Install a support plate at the upper end of the anchor cable, and use the rebound force of the anchor cable to hold the support plate in place, while simultaneously using the support plate to separate the anchor cables one by one. 5) Install a second bearing plate at the upper end of each of the separate anchor cables; 6) Install a compression anchor on the anchor cable, the compression anchor being located above the second bearing plate, and use the second bearing plate to anchor the anchor rod into the bottom plate area to form a second anchor. 7) A concrete mixture is poured in the basement area to form the basement basement slab, thereby fixing the prestressed steel strand anchor rods in the basement basement basement slab.

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