An enlarged head anti-floating anchoring device and construction method

Abstract

This invention provides an enlarged-head anti-buoyancy anchoring device and construction method, relating to the field of anti-buoyancy anchor construction technology. It mainly includes an anchor rod, an anti-corrosion sleeve, and a foundation plate. Addressing the problems of poor corrosion resistance and low pull-out bearing capacity of current anti-buoyancy anchor rods, an anti-corrosion sleeve is installed at the bottom of the anchor rod and connected to a rubber tube. After the rubber tube is filled with grout, it expands to form a raised structure surrounding the anti-corrosion sleeve, improving the durability of the anti-buoyancy anchoring device. The rubber tube has a multi-segment bent structure, and its inclined distribution ensures stable stress distribution and improves its shear resistance. This, combined with the grout injected at the enlarged-head position, enhances the pull-out bearing capacity of the anti-buoyancy anchoring device.

Description

Technical Field

[0001] This invention relates to the field of anti-buoyancy anchor construction technology, specifically to an enlarged head anti-buoyancy anchoring device and construction method. Background Technology

[0002] As one of many anti-buoyancy methods, anti-buoyancy anchors are widely used in structural anti-buoyancy treatment due to their advantages such as strong adaptability to strata, excellent bearing capacity, stress dispersion, and simple construction. For rock strata, anti-buoyancy anchors have good adaptability and reliable pull-out bearing capacity. However, in sandy soil strata, due to the higher porosity and lower cohesion of sand compared to rock strata, the anchoring force of anti-buoyancy anchors is relatively limited. During rainfall or high-water seasons, structures are easily lifted, causing the anti-buoyancy system to fail and affecting structural stability. Furthermore, medium-dense sand layers are highly susceptible to groundwater influence. When the groundwater level rises, sand particles (especially fine sand) rearrange, making the sand structure more compact. This leads to subsidence of the sand layer below the anti-buoyancy anchor, reducing the effective anchoring length and pull-out bearing capacity of the anti-buoyancy anchor. The problem of relatively weak bearing capacity of anti-buoyancy anchors in sandy soil strata needs to be solved. The bearing capacity of anchors can be improved by forming an enlarged head at the end of the anchor. In order to improve the connection strength between the enlarged head formed by grouting and the anchor, multiple transverse metal rods are set in the enlarged head segment of the anchor to form a pin structure to improve pull-out resistance.

[0003] As permanent components, anti-buoyancy anchors are subject to long-term corrosion from corrosive ions such as chloride and sulfate in groundwater, significantly impacting their overall structural durability. The durability of the anti-buoyancy anchors directly determines the safety and service life of the anti-buoyancy structure. Due to the excellent water permeability and conductivity of sandy soil, anti-buoyancy anchors are highly susceptible to corrosion under these humid conditions, reducing their pull-out bearing capacity and durability. Frequent fluctuations in groundwater levels cause repeated wet-dry cycles, further degrading the anchor's strength, reducing its service life, and affecting its long-term pull-out bearing capacity. Therefore, the durability problem of anti-buoyancy anchors in sandy soil is severe. Summary of the Invention

[0004] The purpose of this invention is to address the deficiencies of existing technologies by providing an enlarged head anti-buoyancy anchoring device and its construction method. An anti-corrosion sleeve is installed at the bottom of the anchor rod and connected to a rubber tube. After the rubber tube is filled with grout, it expands to form a raised structure surrounding the anti-corrosion sleeve, improving the durability of the anti-buoyancy anchoring device. The rubber tube has a multi-segment bent structure, and its inclined distribution ensures stable stress distribution and improves its shear resistance. This, combined with the stress from the grout injected at the enlarged head position, enhances the pull-out bearing capacity of the anti-buoyancy anchoring device.

[0005] The first objective of this invention is to provide an enlarged head anti-buoyancy anchoring device, which adopts the following solution:

[0006] An anchor bolt has a washer plate at one end and a preload nut at the other end; a locking nut is fitted at the other end of the anchor bolt.

[0007] The anti-corrosion sleeve is fitted over the anchor rod and one end abuts against the locking nut. A grout cavity is formed between the anti-corrosion sleeve and the anchor rod. Multiple rubber tubes are connected to the outer circumference of the anti-corrosion steel sleeve. The axis of the rubber tubes is a series of broken lines and is coplanar with the axis of the anchor rod. The two ends of the rubber tubes are respectively inclined and connected to different positions of the grout cavity, and the inclination directions are opposite.

[0008] The injection pipe is connected to the slurry cavity to fill the slurry cavity and the rubber tube with slurry, and to expand the rubber tube.

[0009] Furthermore, the rubber tube is connected to the anti-corrosion sleeve to form a closed loop, and an arc-shaped steel plate fixed to the anti-corrosion sleeve is provided inside the closed loop.

[0010] Furthermore, the arc-shaped steel plate passes through the closed ring, and after the rubber tube is filled with slurry and expands, one side contacts the closed ring to cooperate in bearing the force.

[0011] Furthermore, the rubber tube axis is a multi-segment broken line composed of three line segments, with the middle line segment corresponding to the rubber tube axis segment parallel to the anti-corrosion sleeve, so that the rubber tube forms an isosceles trapezoid shape.

[0012] Furthermore, the rubber tube is divided into multiple groups, and the multiple groups of rubber tubes are arranged at intervals along the axial direction of the anti-corrosion sleeve. The multiple rubber tubes included in the same group are arranged at intervals along the ring of the anti-corrosion sleeve.

[0013] Furthermore, the anti-corrosion sleeve is provided with end plates at both ends along the axial direction. The end plates are provided with through holes for anchor rods to pass through, and the end plate at the bottom is connected with a conical protective cap.

[0014] Furthermore, after the anchor rod passes through the concrete pad, waterproof layer, and pad plate in sequence, it is fitted with a pre-tightening nut. Spiral stirrups and main reinforcement bars of the base plate are arranged in the segment area where the anchor rod is located outside the borehole, and concrete is poured to form the foundation base plate connecting the anchor rod.

[0015] Furthermore, the anchor rod is fitted with an anchor rod positioning component on the segment inside the borehole, and a water-stop rubber ring is provided at the opening of the borehole.

[0016] A second objective of the present invention is to provide a construction method for using the enlarged head anti-buoyancy anchoring device as described in the first objective, comprising:

[0017] Mechanical drilling is used to obtain the borehole;

[0018] The anti-corrosion casing and rubber hose are inserted into the borehole along with the anchor rod. Grout is injected into the anti-corrosion casing through the injection pipe to fill the grout cavity and the rubber hose, and to cause the rubber hose to expand.

[0019] Grout is injected into the borehole, and the grout accumulates around the anti-corrosion casing to form an enlarged head. After the grout has cured, prestress is applied by the pre-tightening nut.

[0020] The foundation slab is poured in the segment outside the borehole to establish the connection between the anchor and the foundation slab, and then cured.

[0021] Furthermore, when grouting into the anti-corrosion casing, stabilize the position of the anchor rod and the anti-corrosion casing. After the grout in the rubber tube and grout cavity has solidified and cured, grout is then injected into the borehole.

[0022] Compared with the prior art, the advantages and positive effects of this invention are:

[0023] (1) To address the current problems of poor corrosion resistance and poor pull-out bearing capacity of anti-buoyancy anchors, an anti-corrosion sleeve is installed at the bottom of the anchor and connected to a rubber tube. After the rubber tube is filled with grout, it expands to form a raised structure around the anti-corrosion sleeve, which improves the durability of the anti-buoyancy anchoring device. The rubber tube has a multi-section bent structure, and the inclined distribution structure can make it stable under stress, improve its shear resistance, and work together with the grout injected at the enlarged head position to enhance the pull-out bearing capacity of the anti-buoyancy anchoring device.

[0024] (2) A variable expansion structure is formed at the bottom of the anchor rod. The anti-corrosion sleeve is used as the main body. The anti-corrosion sleeve has a circumferential pre-reserved opening. The two ends of the rubber tube are connected to the opening. The rubber tube is filled by grouting inside the anti-corrosion sleeve. After filling, the rubber tube forms multiple protrusions in the circumferential direction of the anti-corrosion sleeve. Grout is injected into the borehole at the bottom of the anchor rod to form an enlarged head. The enlarged head increases the contact area with the soil layer, and the protrusions increase the contact area between the rubber tube and the enlarged head, thereby improving the bearing capacity.

[0025] (3) By adding an arc-shaped steel plate, the stability of the rubber tube connection to the anti-corrosion sleeve is increased, and the synergistic force is achieved, so as to better exert the bearing capacity of the enlarged head.

[0026] (4) Spiral stirrups are provided at the contact point between the anchor rod and the foundation plate, which can effectively increase the contact area between the anchor rod and the foundation plate, thereby enhancing the bonding strength between the anchor rod and the foundation plate and improving the anchoring force between the anchor rod and the foundation plate.

[0027] (5) In view of the problem that traditional metal rods are prone to corrosion and failure in anchoring and stopping structures, the present invention uses rubber tubes to avoid the corrosion of external water bodies and ensure the stability of the rubber tubes and their internal stopping structures during long-term service.

[0028] (6) The two ends of the rubber tube are respectively connected to the anti-corrosion sleeve. After the slurry is injected into the rubber tube and solidifies, it forms an approximately closed polygonal structure, close to the shape of a trapezoid. The inclined distribution structure can make it stable under stress, improve its shear resistance, solve the problem of poor pull-out resistance caused by the small aperture of the rubber tube connecting to the anti-corrosion sleeve, and ensure its pull-out resistance. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a schematic diagram of the enlarged head anti-buoyancy anchoring device in Embodiments 1 and 2 of the present invention.

[0031] Figure 2 This is a schematic diagram of the anti-corrosion sleeve in Embodiments 1 and 2 of the present invention.

[0032] Figure 3 This is a schematic diagram of the specially made anchor plate in Embodiments 1 and 2 of the present invention.

[0033] Figure 4 This is a schematic diagram of the anchor positioning component in Embodiments 1 and 2 of the present invention.

[0034] Figure 5 This is a schematic diagram of the pad and preload nut in Embodiments 1 and 2 of the present invention.

[0035] Figure 6 This is a schematic diagram of the waterproof layer and concrete pad layer in Embodiments 1 and 2 of the present invention.

[0036] Figure 7 This is a schematic diagram of the anti-corrosion sleeve end plate in Embodiments 1 and 2 of the present invention.

[0037] The components include: 1. Drilling hole; 2. Foundation slab; 3. Main reinforcement of the foundation slab; 4. Waterproof layer; 5. Concrete pad; 6. Pad; 7. Special anchor plate; 8. Pre-tightening nut; 9. Spiral stirrup ring; 10. Locking anchor plate; 11. Water-stop rubber ring; 12. End plate; 13. Injection pipe; 14. Exhaust pipe; 15. Anti-corrosion sleeve; 16. Rubber tube; 17. Circular steel pad; 18. Locking nut; 19. Protective cap; 20. Anchor rod; 21. Anchor rod positioning component; 22. Arc-shaped steel plate; 23. Waterproof sleeve. Detailed Implementation

[0038] Example 1

[0039] In a typical embodiment of the present invention, such as Figures 1-7 As shown, an enlarged head anti-buoyancy anchoring device is presented.

[0040] When existing anti-buoyancy anchors are placed in sandy soil, the sandy soil has good water permeability and water conductivity, making the anti-buoyancy anchors prone to corrosion under humid conditions, which reduces the pull-out bearing capacity and durability of the anti-buoyancy anchors.

[0041] Based on this, this embodiment provides an enlarged head anti-buoyancy anchoring device, which is suitable for anti-buoyancy structures in sandy soil strata. By establishing an enlarged head area and increasing the connection strength between the anchor rod 20 and the enlarged head, the pull-out bearing capacity of the anti-buoyancy anchoring device is improved. The anti-corrosion sleeve 15 combined with the rubber tube 16 is used to connect with the enlarged head area to ensure durability during the anchoring process.

[0042] The enlarged head anti-buoyancy anchoring device will now be described in detail with reference to the accompanying drawings.

[0043] See Figure 1 The enlarged head anti-buoyancy anchoring device mainly includes an anchor rod 20, an anti-corrosion sleeve 15, and a foundation plate 2. One end of the anchor rod 20, located outside the borehole 1, is fitted with a pad 6 and a pre-tightening nut 8, and is connected to the foundation plate 2. The other end of the anchor rod 20 is fitted with a locking nut 18. The anti-corrosion sleeve 15 is fitted outside the anchor rod 20, with one end abutting against the locking nut 18. A grout cavity is formed between the anti-corrosion sleeve 15 and the anchor rod 20. Multiple rubber tubes 16 are connected to the outer circumference of the anti-corrosion steel sleeve. An injection pipe 13 is connected to the grout cavity to fill the grout cavity and the rubber tubes 16, and to expand the rubber tubes 16, so that they share the force with the enlarged head formed by the grout injected into the borehole 1, thereby achieving anti-buoyancy.

[0044] In this embodiment, as Figure 1 As shown, borehole 1 is formed using a mechanical reaming method. The hole depth and anchor hole deviation should not exceed 5%. The hole diameter deviation should not exceed 20mm, and the hole depth is generally 200-300mm greater than the design depth. The horizontal and vertical hole spacing error of anchor rod 20 should not exceed 100mm. The drill bit diameter should not be less than the designed borehole 1 diameter by 3mm. The anchor hole borehole 1 depth should not be less than the designed anchorage length, nor should it exceed the designed anchorage length by 500mm.

[0045] The foundation slab 2 is a general raft foundation, poured with 42.5 ordinary Portland cement. The foundation slab 2 contains main reinforcement bars 3, the diameter of which is determined according to design requirements. In this embodiment, the main reinforcement bars 3 are HRB400 steel bars with a diameter of 18mm and a spacing of 150mm.

[0046] A waterproof layer 4 and a concrete pad 5 are installed between the foundation slab 2 and the ground. The waterproof layer 4 is composed of mortar waterproofing agent, cement, sand, fine aggregate, and fiber, with a thickness of not less than 200mm, to provide initial waterproofing and reduce corrosion of the anchor bolts 20. The ratio of water, cement, and sand in the waterproof layer 4 is 3:1:2, and the waterproofing agent accounts for 3% to 5% of the total weight of sand and cement. The waterproof layer 4 is laid on top of the concrete pad 5, and its construction is carried out after the pre-tightening force of the anchor bolts 20 is applied.

[0047] The concrete cushion layer 5 is made of C20 fine aggregate concrete with a thickness of 100-150mm. The concrete cushion layer provides a solid and stable foundation, which helps to disperse and transfer structural loads, prevent foundation settlement or uneven settlement, and thus ensure the stability of the anti-buoyancy system.

[0048] like Figure 6 As shown, the anchor rod 20 passes through the concrete pad 5, waterproof layer 4, and pad plate 6 in sequence, and is then fitted with a pre-tightening nut 8. Spiral stirrups 9 and main reinforcement bars 3 are arranged in the segment area outside the borehole 1, and concrete is poured to form the foundation plate 2 connecting the anchor rod 20. In this embodiment, a special anchor plate 7 and a locking anchor plate 10 are also provided outside the anchor rod 20, and the pre-tightening nut 8 abuts against the locking anchor plate 10.

[0049] The pad 6 is a 400mm×400mm×25mm steel plate. An anchor rod 20 is pre-drilled in the center of the steel plate to pass through the required hole, and the hole diameter is 45mm. To ensure the safety of applying pre-tightening force to the anchor rod 20, the pre-tightening nut 8 is located above the pad 6, and below it are the waterproof layer 4 and the concrete pad layer 5.

[0050] like Figure 3 As shown, the locking anchor plate 10 is placed above the special anchor plate 7. The special anchor plate 7 is a specially made square steel plate with a thickness of 20mm. Its shape is a "flat-bottomed concave shape," with a 200mm square at the center, and both sides curving upwards at 135°, extending outwards by 600mm to form a 600mm square. The special anchor plate 7 is placed on top of the spiral stirrup ring 9 and fixed by the locking anchor plate 10 in conjunction with the preload nut 8. Figure 5 As shown, the preload nut 8 can be used to apply preload to the anchor rod 20 using a torque wrench. The magnitude of the preload is determined by the anti-buoyancy design requirements and the needs of the construction equipment. The preload nut 8 is a flange nut with a diameter of 200mm, a thickness of 20mm, and a height of 100mm.

[0051] The spiral stirrup ring 9 is made of threaded steel bars with a diameter of 8mm and a stirrup spacing of 100mm. The spiral stirrup ring 9 formed has a radius of 300mm and is located between the special anchor plate 7 and the pad plate 6. It can increase the contact area between the foundation plate 2 and the anchor rod 20, thereby improving the anchoring force between the anchor rod 20 and the foundation plate 2.

[0052] The locking anchor plate 10 is made of a steel plate with a side length of 200mm and a thickness of 100mm. A 45mm diameter hole is reserved in the center to firmly lock the anchor rod 20. The locking anchor plate 10 is located above the special anchor plate 7 and can effectively fix the special anchor plate 7 and the spiral hoop ring 9 by abutting the pre-tightening nut 8.

[0053] like Figure 4 and Figure 6 As shown, the anchor rod 20 is fitted with an anchor rod positioning component 21 on the segment inside the borehole 1, and the anchor rod 20 is provided with a water-stopping rubber ring 11 at the opening position of the borehole 1.

[0054] The water-stop rubber ring 11 prevents water or other liquids from seeping into the space or structure around the anchor rod 20. The water-stop rubber ring 11 is fitted onto the anchor rod 20, located above the concrete pad 5, and is evenly distributed at 100mm intervals. Its main function is to form a sealed barrier to prevent groundwater from rising and entering the superstructure, thereby maintaining the integrity and safety of the anti-buoyancy engineering structure.

[0055] like Figure 2 As shown, the axis of the rubber tube 16 is a multi-segment broken line and is coplanar with the axis of the anchor rod 20; the two ends of the rubber tube 16 are respectively connected to different positions of the slurry cavity in an inclined state, and the inclination directions are opposite; the rubber tube 16 is connected to the anti-corrosion sleeve 15 to form a closed ring, and an arc-shaped steel plate 22 fixed to the anti-corrosion sleeve 15 is provided in the closed ring.

[0056] In this embodiment, the arc-shaped steel plate 22 passes through the closed ring. After the rubber tube 16 is filled with slurry and expands, one side contacts the closed ring to cooperate in bearing the force. The axis of the rubber tube 16 is a multi-segment broken line composed of three line segments. The middle line segment corresponding to the axis segment of the rubber tube 16 is parallel to the anti-corrosion sleeve 15, so that the rubber tube 16 forms an isosceles trapezoid shape. This allows the shear force on the rubber tube 16 during the pull-out process to be transmitted to the anti-corrosion sleeve 15 in an inclined state, thereby preventing the rubber tube 16 and the solidified slurry inside from breaking at the position connecting to the anti-corrosion sleeve 15 and optimizing its stress state.

[0057] like Figure 7 As shown, the anti-corrosion sleeve 15 has end plates 12 at both ends of its axial direction. The end plates 12 have through holes for the anchor rod 20 to pass through, and the end plate 12 at the bottom is connected to a conical protective cap 19.

[0058] The end plate 12 has pre-drilled openings for installing the injection pipe 13 and the vent pipe 14. The opening on the upper end plate 12 can be a 40mm diameter hole, while the lower end plate 12 does not require openings for installing the injection pipe 13 and the vent pipe 14. The through hole on the end plate 12 for the anchor rod 20 to pass through is a threaded through hole adapted to the thread on the anchor rod 20, so that the anti-corrosion sleeve 15 can be fixed to the anchor rod 20 through the end plate 12. At the same time, the end plate 12 can also seal the end of the anti-corrosion sleeve 15 through the threaded connection, ensuring that the grout can completely fill the rubber tube 16, ensuring the integrity of the enlarged head structure and function.

[0059] The injection pipe 13 has a diameter of 25mm, which facilitates the later grouting inside the anti-corrosion sleeve 15, so that the cement slurry completely fills the rubber tube 16, forming a stress-bearing area with a protruding structure at the bottom of the anchor rod 20.

[0060] The vent pipe 14 has a diameter of 20mm. Its purpose is to expel the gas inside the anti-corrosion sleeve 15 in a timely manner during grouting, so as to avoid the formation of internal holes when the cement grout sets and to ensure the strength of the enlarged head.

[0061] In this embodiment, the anti-corrosion sleeve 15 is 1400mm long and 45mm in diameter, which can better protect the end of the anchor rod 20 from corrosion. The anti-corrosion sleeve 15 is circumferentially connected to the rubber tube 16. The rubber tube 16 can be fully expanded by the grouting pressure. The diameter of the rubber tube 16 is 25mm. After grouting, the anti-corrosion sleeve 15 and the rubber tube 16 work together to bear the force.

[0062] The rubber tube 16 is connected to the anti-corrosion sleeve 15 at both ends. After the slurry is injected into the rubber tube 16 and solidifies, it forms an approximately closed polygonal structure, close to a trapezoidal shape. The inclined distribution structure can make it stable under stress, improve its shear resistance, solve the problem of poor pull-out resistance caused by the small aperture of the rubber tube 16 connecting to the anti-corrosion sleeve 15, and ensure its pull-out resistance.

[0063] Anchor rod 20 can be made of PSB1080 fine-rolled threaded steel bar with a diameter of 36mm. The anchorage length is determined by the design drawings. PSB1080 fine-rolled threaded steel bar has high tensile strength, can withstand large preload, and also has strong corrosion resistance.

[0064] The arc-shaped steel plate 22 is a circular arc-shaped steel plate with an arc length of 20mm, a height of 10mm, and a thickness of 5mm. The arc-shaped steel plate 22 is fixed to the anti-corrosion sleeve 15 by welding. After the rubber tube 16 expands, its inner ring can fit and contact the arc-shaped steel plate 22. After the grout solidifies, the arc-shaped steel plate 22 and the rubber tube 16 work together to bear the force.

[0065] A circular steel pad 17 is abutted between the bottom end plate 12 of the anti-corrosion sleeve 15 and the locking nut 18 to disperse the pressure of the locking nut 18 on the anti-corrosion steel sleeve and reduce stress concentration.

[0066] The circular steel pad 17, made of Q335 carbon steel, has a diameter of 130mm and a thickness of 25mm, providing a larger bottom support area and increasing the pull-out bearing capacity of the anchor 20. This allows the anchor 20 to better resist the buoyancy of groundwater, improving the stability of the entire anti-buoyancy structure. Furthermore, the use of the circular steel pad 17 reduces the risk of sinking and slippage at the bottom of the anchor 20, especially in loose or unstable soil or fractured rock geological conditions. It helps ensure that the anchor 20 is securely fixed in the position shown in the construction drawings.

[0067] The locking nut 18 is made of alloy steel, with a diameter of 36mm, a thickness of 10mm, and a height of 100mm. It can improve the stress state of the anchor rod 20 and transfer the load to the surrounding strata or foundation plate 2 through the anchor rod 20.

[0068] The end plate 12 at the bottom is connected to a conical protective cap 19, which is made of stainless steel and coated with a waterproof coating. The cap is 100 mm in diameter and 150 mm in height. The protective cap 19 protects the head of the anchor bolt 20 from damage and corrosion from the external environment. This includes preventing the anchor head from being eroded and damaged by water, soil, chemicals or other corrosive ions, which helps to extend the service life of the enlarged head anchor bolt 20.

[0069] The waterproof sleeve is made of stainless steel and consists of two hollow cylinders. The sleeve is fixed to the anchor rod 20 by bolts. At the same time, a certain space is left in the middle of the sleeve, which is filled with grease to effectively prevent water from floating. There are baffles inside the bolt fixing positions at both ends to prevent the filling fluid from flowing out.

[0070] Example 2

[0071] In another typical embodiment of the present invention, such as Figures 1-7 As shown, a construction method for using an enlarged head anti-buoyancy anchoring device is presented.

[0072] The method of using the enlarged head anti-buoyancy anchoring device as described in Example 1 includes the following steps:

[0073] Hole 1 was obtained by mechanical drilling;

[0074] The anti-corrosion sleeve 15 and rubber tube 16 enter the borehole 1 along with the anchor rod 20. Grout is injected into the anti-corrosion sleeve 15 through the injection pipe 13 to fill the grout cavity and rubber tube 16, and to expand the rubber tube 16.

[0075] Grout is injected into borehole 1. The grout accumulates around the anti-corrosion casing 15 to form an enlarged head. After the grout curing is completed, prestress is applied by the pre-tightening nut 8.

[0076] The foundation slab 2 is poured in the segment outside the borehole 1 to establish the connection between the anchor rod 20 and the foundation slab 2, and then cured.

[0077] When grouting into the anti-corrosion sleeve 15, stabilize the position of the anchor rod 20 and the anti-corrosion sleeve 15. After the grout in the rubber tube 16 and the grout cavity has solidified and cured, grout is then injected into the borehole 1.

[0078] Specifically, in conjunction with Example 1 and Figure 1-7 The construction method of using the enlarged head anti-buoyancy anchoring device is described in detail.

[0079] 1. Anchor hole positioning:

[0080] A total station was used to measure the elevation of the construction site to determine the depth of borehole 1. At the same time, the borehole 1 was laid out to determine the position of the anchor hole. According to the relevant requirements of the technical specification of anchor rod 20 (YB / T4659-2018) and the design drawings, the error of the hole position laying out should not be greater than 20mm, and the mechanical positioning error should not be greater than 50mm.

[0081] 2. Anchor bolt hole drilling construction:

[0082] Mechanical drilling is employed, with a spirit level used to calibrate the levelness of the construction platform and turntable, ensuring the deviation between the turntable center and the designed pile position is no more than 20mm. During drilling rig positioning, the verticality of the drill frame is corrected, and the verticality, levelness, and turntable center displacement of the drilling rig are frequently observed and checked during drilling. The hole diameter deviation is no more than 20mm, and the depth of anchor hole 1 should not be less than the designed length, nor should it exceed the designed length by 500mm; the axial deviation rate of borehole 1 should not exceed 2% of the length of anchor rod 20; waterproof casing 23 is used for hole forming. After drilling and lowering the rod to the designed depth, 5-10mm gravel can be used for filling before pipe extraction and grouting. High-pressure jet reaming uses cement slurry, which contains HR-SS-W-S1 type soft soil solidifying agent. The main components of the solidifying agent are mineral powder, cement, gypsum, and lime, which can solidify the sand layer, improve the soil microstructure, and effectively prevent hole bottom collapse caused by jet grouting. When using cement slurry to expand the borehole, the borehole should be expanded at least twice, up and down. The injection pressure for expanding the borehole should not be less than 20 MPa, the nozzle feed or lifting speed can be 10-25 cm / min, and the nozzle rotation speed can be 5-15 r / min.

[0083] 3. Fabrication of the enlarged head anti-buoyancy anchoring device:

[0084] Coordinate the fabrication and drilling time of the enlarged head anti-buoyancy anchoring device, aiming to complete the drilling immediately after fabrication to minimize the idle time of the enlarged head anti-buoyancy anchoring device; the anchor rod 20 is mainly composed of PSB1080 threaded steel bars with a diameter of 36mm; an anchor rod positioning component 21 is installed every 4.0m along the axis of the rod body; the anchoring section is connected to the anti-corrosion sleeve 15, the anchor rod 20 is passed through the reserved hole of the end plate 12, the end plate 12 is connected to the anti-corrosion sleeve 15, and the top of the anti-corrosion sleeve 15 is connected to the injection pipe 13; select a level site at the construction site to place the anchor rod 20 and anti-corrosion sleeve 15 that have completed anti-corrosion coating, and the anti-corrosion coating work of the anchor rod 20 is completed at the factory.

[0085] 4. Anchor bolt 20 construction and grouting:

[0086] The pre-assembled anchor bolts 20 are manually and quickly placed into the borehole 1. After the borehole is enlarged, the nozzle is immediately removed and the anchor bolts 20 are placed into the anchor hole to the designed depth. When using waterproof sleeves 23 to protect the borehole 1, the sleeves are pulled out after the anchor bolts 20 are placed into the borehole 1 to the designed depth.

[0087] When installing the anchor rod 20, take care to prevent the anchor rod 20 from bending or the anti-corrosion sleeve 15 from falling off; after the grouting pipe is connected to the anti-corrosion sleeve 15, it is inserted into the anchor hole together with the anchor rod 20, with the height protruding above the ground not less than 1m.

[0088] After the anchor bolt 20 is lowered to the designed position, grouting begins. The medium-pressure pump is connected to the injection pipe 13 through the grouting pipe to grout the anti-corrosion sleeve 15. The water-cement ratio of the grout is 0.45, and the grouting pressure is 1-2 MPa. The grouting pressure will fill and expand the rubber tube 16. The grout used is non-bleeding cement.

[0089] After completing the grouting of the anti-corrosion sleeve 15 without bleeding, loosen the joint between the grouting pipe and the injection pipe 13 on the anti-corrosion sleeve 15. Then, through the detached grouting pipe, inject clean cement grout around the anti-corrosion sleeve 15 and the upper anchor bolt 20 holes. The injection pressure should not exceed 1 MPa, and the injection should be stopped when the color of the grout returning from the hole mouth becomes significantly darker.

[0090] During grouting, wait for the cement slurry to overflow from the hole before pulling out the grouting pipe. Continuously replenish the grout as it shrinks until there is no shrinkage in borehole 1. After grouting, a curing period of more than 3 days is required before subsequent construction can proceed. During the curing period, the pole must not be struck or heavy objects must not be hung on it.

[0091] 5. Apply preload

[0092] After the anchor bolt 20 is installed, install the pad 6. During installation, pay attention to keeping the anchor bolt 20 in the center position.

[0093] Install the spiral stirrup ring 9, and install the locking anchor plate 10 at the upper end of the anchor rod 20 to firmly fix the spiral stirrup ring 9 between the pad plate 6 and the special anchor plate 7.

[0094] Install the special anchor plate 7 and the preload nut 8. Apply the preload by turning the preload nut 8 with a torque wrench. The specific preload amount is determined by the actual anti-buoyancy requirements and the needs of the construction equipment. After the preload is applied, tighten the preload nut 8 and install a waterproof rubber ring below the preload nut 8.

[0095] 6. Building foundation construction

[0096] After the installation of the exposed anchor rod 20 and related components is completed, the foundation slab 2 is constructed. First, the concrete cushion layer 5 is constructed. After the concrete has cured, a cement-based penetrating crystalline waterproofing material is applied around the drilled hole 1. The waterproof sleeve 23 is then fixed to the anchor rod 20, and the waterproof layer 4 is constructed. Following this, the main reinforcement bars 3 of the foundation slab are tied. After the reinforcement binding is completed, formwork is erected and the foundation slab concrete is poured. The concrete is cured within 8-12 hours after pouring, and the curing time should not be less than 7 days. The specific curing time is determined according to the actual project requirements.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An enlarged head anti-float anchor assembly, comprising: include: Anchor bolts have a pad at one end and are fitted with a preload nut; The other end of the anchor bolt is fitted with a locking nut; An anti-corrosion sleeve is fitted over the anchor rod, with one end abutting against a locking nut. A grout cavity is formed between the anti-corrosion sleeve and the anchor rod. Multiple rubber tubes are connected to the outer circumference of the anti-corrosion steel sleeve. The axis of each rubber tube is a multi-segment broken line and is coplanar with the axis of the anchor rod. The two ends of the rubber tubes are inclined and connected to different positions in the grout cavity, with opposite inclination directions. The rubber tubes connect to the anti-corrosion sleeve to form a closed loop. An arc-shaped steel plate is fixed to the anti-corrosion sleeve inside the closed loop. The arc-shaped steel plate passes through the closed loop. After the rubber tubes are filled with grout and expand, one side contacts the closed loop to cooperate in bearing the force. The axis of each rubber tube is a multi-segment broken line composed of three line segments. The middle line segment corresponding to the rubber tube axis segment is parallel to the anti-corrosion sleeve, making the rubber tube form an isosceles trapezoid shape. The injection pipe is connected to the slurry cavity to fill the slurry cavity and the rubber tube with slurry, and to expand the rubber tube.

2. The enlarged head anti-buoyancy anchoring device as described in claim 1, characterized in that, The rubber tubes are divided into multiple groups, and the multiple groups of rubber tubes are arranged at intervals along the axial direction of the anti-corrosion sleeve. The multiple rubber tubes included in the same group are arranged at intervals along the ring of the anti-corrosion sleeve.

3. The enlarged head anti-buoyancy anchoring device as described in claim 1, characterized in that, The anti-corrosion sleeve is provided with end plates at both ends of the axial direction. The end plates are provided with through holes for anchor rods to pass through, and the end plate at the bottom is connected to a conical protective cap.

4. The enlarged head anti-buoyancy anchoring device as described in claim 1, characterized in that, The anchor rod passes through the concrete pad, waterproof layer, and pad plate in sequence, and is then fitted with a pre-tightening nut. Spiral stirrups and main reinforcement bars of the base plate are arranged in the segment area outside the borehole, and concrete is poured to form the foundation base plate connecting the anchor rod.

5. The enlarged head anti-buoyancy anchoring device as described in claim 4, characterized in that, The anchor rod is fitted with an anchor rod positioning component on the segment inside the borehole, and a water-stop rubber ring is provided at the opening of the borehole.

6. A construction method using the enlarged head anti-buoyancy anchoring device as described in any one of claims 1-5, characterized in that, include: Mechanical drilling is used to obtain the borehole; The anti-corrosion casing and rubber hose are inserted into the borehole along with the anchor rod. Grout is injected into the anti-corrosion casing through the injection pipe to fill the grout cavity and the rubber hose, and to cause the rubber hose to expand. Grout is injected into the borehole, and the grout accumulates around the anti-corrosion casing to form an enlarged head. After the grout has cured, prestress is applied by the pre-tightening nut. The foundation slab is poured in the segment outside the borehole to establish the connection between the anchor and the foundation slab, and then cured.

7. The construction method of the anti-buoyancy anchoring device using the enlarged head as described in claim 6, characterized in that, When grouting into the anti-corrosion casing, stabilize the position of the anchor rod and the anti-corrosion casing. After the grout in the rubber tube and grout cavity has solidified and cured, then grout is injected into the borehole.

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