Construction method of heat shrinkage cage core bag expanded head anchor rod

Abstract

The invention provides a construction method of a heat-shrinkable cage core capsule expanded-head anchor rod, and belongs to the technical field of anchor rod construction.The construction method of the heat-shrinkable cage core capsule expanded-head anchor rod comprises the following steps that an anchor rod body is coated with epoxy asphalt with the thickness not smaller than 300 micrometers from a hole opening to a capsule bag opening, and the anchor rod body is wrapped with a heat-shrinkable tube to be heated and shrunk; the buckle bearing bodies are installed every 1500 mm, and the cage core bags are installed at the ends of the anchor rods and locked and fixed through bolts; after the cushion layer is poured, paying off and positioning are conducted according to a design drawing, and the hole position error is not larger than 100 mm; manual assistance is needed for lowering the anchor rod, and the distance between the end of the rod body and the hole bottom is not larger than 100 mm; ordinary Portland cement is adopted for grouting, the strength is not lower than 35 MPa, and the opening diameter of the bag is monitored; supplementing grout 2 hours after grouting; after raft waterproof construction, spiral bars, positioning nuts and other parts are installed, steel bars are welded to the steel base plates to serve as temporary supports, and the positioning nuts are adjusted to keep the elevation and are connected with raft ribs in a welded mode; the bearing capacity of the anchor rod can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of anchor rod construction, and in particular relates to a method for constructing an anchor rod with a heat shrinkable cage core bag and an enlarged head. Background Art

[0002] In the field of construction and civil engineering, anchor rods are widely used in various foundation projects as an important means of foundation reinforcement. Usually, anchor rods will pass through soil layers or weak rock layers and form a reliable anchor connection with hard bedrock or concrete layers, thereby enhancing the bearing capacity, anti-slip ability and anti-overturning ability of the foundation. At present, the common types of anchor rods mainly include prestressed anchor rods, chemical anchor rods and mechanically enlarged head anchor rods. Among them, mechanically enlarged head anchor rods are widely used due to their advantages such as simple construction and stable performance.

[0003] Prestressed anchors require high-strength steel bars or steel strands to be pre-arranged inside the anchors, and prestress is applied by tensioning to improve the pull-out resistance of the anchors. Chemical anchors inject high-strength chemical resin materials into the borehole to form a reliable bond and anchor with the hole wall. These two methods have improved the bearing capacity of anchors to a certain extent, but they require professional equipment and complex processes during construction, which makes the operation difficult and also has the problem of high material costs. In contrast, mechanically enlarged head anchors increase the anchor volume and contact area by pre-enlarging the hole diameter at the bottom of the hole to improve the overall pull-out resistance. This method is simple to construct, does not require complex professional equipment, and does not have the problem of excessively high material costs. Therefore, it is widely used in various foundation reinforcement projects.

[0004] However, the existing mechanically enlarged head anchors still have some problems to be solved in practical application. In large-span and large-load projects, the bearing capacity of a single anchor is often difficult to meet the requirements, and multiple anchors need to be combined, which undoubtedly increases the difficulty and cost of construction. Summary of the invention

[0005] In view of this, the present invention provides a heat shrinkable cage core bag enlarged head anchor rod construction method, which can improve the bearing capacity of the anchor rod, eliminate the need for a plurality of anchor rods to meet the bearing requirements, reduce construction difficulty, and reduce construction costs.

[0006] The present invention is achieved in that:

[0007] The present invention provides a heat shrinkable cage core bag enlarged head anchor rod construction method, which comprises the following steps:

[0008] S10, performing anti-corrosion treatment on the anchor rod body, coating the anchor rod body from below the hole to the bag mouth with epoxy asphalt, with a coating thickness of not less than 300 microns, and wrapping the rod body with a heat shrink tube, and evenly heating the heat shrink tube with a hot air gun to shrink and wrap around the rod body;

[0009] S20, assemble the anchor rod, install the buckle bearing body at every 1500 mm interval on the rod body, install the cage core bag at the end of the anchor rod, use the transverse bolt to bite and lock the upper locking buckle sleeve to the anchor rod body, and use the axial bolt to connect and fix the bag cage core with the upper locking buckle;

[0010] S30. After the cushion layer is poured, the positioning is carried out, and the hole positions are marked according to the design drawings. The hole spacing error of the anchor rod in the horizontal and vertical directions is not greater than 100 mm;

[0011] S40, perform drilling operations, the diameter of the drill hole is not less than 160 mm, the diameter of the enlarged hole is not less than 700 mm, the length is not less than 3000 mm, and the water enlargement time is controlled between 35 minutes and 60 minutes;

[0012] S50, lowering the anchor rod, inserting the anchor rod into the hole by means of a manual auxiliary drilling rig, with the end of the rod body no more than 100 mm from the bottom of the hole, and providing a buckle carrier on the rod body at intervals of 1500 mm;

[0013] S60, grouting the bag, using ordinary Portland cement for grouting, the cement slurry bulk density is not less than 1.82, the anchor body 28-day strength is not less than 35 MPa, and the bag opening diameter is monitored by the grouting monitoring instrument to reach the design value;

[0014] S70, 2 hours after the grouting is completed, grouting is performed to inject additional cement slurry into the borehole;

[0015] S80. After the waterproofing of the raft slab is completed and before the raft slab reinforcement is laid, install the spiral reinforcement, positioning nuts, steel pads, and precision nuts;

[0016] S90. Weld steel bars on the steel plate as temporary support, adjust the positioning nuts to keep the steel plate at the same elevation, and weld the horizontal bidirectional reinforcement of the raft slab to the temporary support.

[0017] On the basis of the above technical solution, the heat shrinkable cage core bag enlarged head anchor rod construction method of the present invention can also be improved as follows:

[0018] Among them, the step S10 specifically includes: selecting finely rolled steel bars to make the anchor rod body, using professional epoxy asphalt coating equipment to evenly coat the surface of the anchor rod body with epoxy asphalt as an inner anti-corrosion layer, and controlling the thickness of the inner anti-corrosion layer to be not less than 300 microns. After the surface of the epoxy asphalt reaches a surface dry state, the heat shrink tube is put on the outside of the inner epoxy asphalt coating as an outer anti-corrosion layer, and a professional hot air gun is used to reciprocate and heat along the axial direction of the anchor rod body to make the heat shrink tube evenly heated and produce a thermal compression shrinkage effect, ensuring that the heat shrink tube and the inner epoxy asphalt coating fit tightly to form a double anti-corrosion protection structure.

[0019] Furthermore, the step S20 specifically includes: first, installing a buckle carrier assembly at intervals of 1500 mm along the length direction of the anchor rod body, the buckle carrier assembly is made of high-strength engineering plastic to form an annular buckle body, the inner surface of the annular buckle body is provided with an annular groove with anti-slip patterns, and the outer surface is provided with radial positioning ribs in a star-shaped array, and the ends of the radial positioning ribs are equipped with arc-shaped protective caps; then, the locking buckle, sealing sleeve, bag body, cage core frame and bottom locking piece are installed in sequence on the end of the anchor rod, and the annular locking buckle body and the sealing sleeve are locked and fixed to the anchor rod body by transverse fixing bolts, the sealing sleeve is made of elastic material to form an interference fit with the rod body, the cage core frame is welded by annular steel bars and longitudinal connecting ribs and is placed inside the bag body, and the bag body is made of flexible waterproof material and fixedly connected to the anchor rod body by the bottom locking piece.

[0020] Furthermore, the step S30 specifically includes: after the concrete cushion layer is poured and reaches the design strength requirement, the surveying personnel shall lay out and locate the anchor holes according to the marking requirements of the design drawings, use a total station to accurately locate and measure the anchor holes, use white lime to mark the hole positions, and strictly control the horizontal and vertical hole spacing errors of the anchors to be no more than 100 mm. After the measurement is completed, self-inspection shall be carried out and reported to the supervisor for review. Subsequent construction work can only be carried out after approval by the supervisor.

[0021] Furthermore, the step S40 specifically includes: using professional drilling equipment to perform hole-forming operations, controlling the borehole diameter to be no less than 160 mm, using a special reaming drill bit to expand the head section for hole expansion construction, the hole diameter is no less than 700 mm, and the length of the reaming section is no less than 3000 mm, using a clean water punching process to expand the hole, strictly controlling the clean water expansion time between 35 minutes and 60 minutes, and continuously observing the return water situation until the return water color is the same as the clean water color to ensure that the drilling quality meets the design requirements.

[0022] Furthermore, the step S50 specifically includes: the construction personnel cooperate with the drilling rig equipment to slowly insert the heat shrink cage core bag enlarged head anchor rod along the axial direction of the borehole, strictly control the distance between the end of the anchor rod body and the bottom of the hole to not exceed 100 mm, and focus on observing the gap state between the radial positioning ribs of the snap-on carrier assembly and the borehole wall during the lowering process, and ensure that the radial positioning ribs are not stuck by adjusting the lowering speed and angle, and at the same time use the snap-on carrier assembly to achieve the centering effect of the anchor rod body in the borehole.

[0023] Furthermore, the step S60 specifically includes: selecting 42.5 grade ordinary Portland cement to prepare grouting slurry, strictly controlling the bulk density of cement slurry to be not less than 1.82, ensuring through test block test that the 28-day compressive strength of the anchor body is not less than 35 MPa, installing professional grouting monitoring instruments on the grouting pipeline, monitoring the grouting pressure and the bag opening status in real time, and terminating the grouting operation only when the grouting monitor shows that the bag opening diameter has reached the design specified value and the system prompts that the stop conditions have been met.

[0024] Furthermore, the step S70 specifically includes: 2 hours after the bag grouting operation is completed, the drill hole is supplemented with cement slurry with the same ratio as the bag grouting, and the return grouting at the hole mouth is closely observed during the grouting process. When the color and concentration of the return grouting are basically consistent with the injected slurry, the grouting is stopped to ensure that the grouting fullness meets the design requirements and effectively improves the strength of the anchor body.

[0025] Furthermore, the step S80 specifically includes: after the raft slab waterproofing construction is completed but before the raft slab steel bars are laid, installing the top fixing assembly, which includes spiral bars, steel pads, positioning nuts and precision-tied nuts in sequence, the spiral bars adopt a spiral steel bar structure with a pitch of 50 mm and a twisted anti-slip pattern on the surface, the steel pads adopt a square steel plate structure with diagonal reinforcement ribs with a triangular cross-section on the upper surface and positioning bosses distributed in an annular array at the edge of the lower surface, and the positioning nuts and precision-tied nuts are adjusted to form a stable locking connection between the components.

[0026] Furthermore, the step S90 specifically includes: using a laser level to project a horizontal elevation control line, maintaining all steel pads in the same elevation plane by accurately adjusting positioning nuts and precision nuts, welding steel bars on the steel pads as temporary support members, and welding and fixing the horizontal bidirectional steel bars of the raft slab to the temporary support after they are in place to form a stable support system, and when the design thickness of the raft slab exceeds 1500 mm, adding diagonal bracing members at the temporary support position of the anchor rod to ensure the overall stability of the anchor rod stirrup.

[0027] The heat-shrinkable cage core bag enlarged head anchor rod proposed in the present invention has achieved remarkable results in solving the key problems in the prior art. First, the double anti-corrosion layer design of the inner layer epoxy asphalt coating and the outer layer heat shrink tube is adopted on the surface of the anchor rod, which greatly improves the corrosion resistance of the anchor rod in harsh underground environments and ensures its long-term reliable use. Secondly, by setting an expandable bag assembly at the bottom of the hole, not only the contact area and volume of the anchor body are increased, but also the opening degree of the bag can be adjusted according to actual conditions, further improving the overall bearing capacity of the anchor rod. Furthermore, an adjustable fixing mechanism is set at the top of the anchor rod, including spiral ribs, steel pads and multi-stage nuts, which can adapt to different engineering environments and load conditions and improve the overall stability. In addition, compared with the traditional practice of using multiple anchor rods, the single anchor rod proposed in the present invention can meet the needs of large-span and large-load projects, greatly simplifying the construction process and reducing engineering costs.

[0028] In order to better improve the performance of the heat shrinkable cage core capsule enlarged head anchor rod, the relationship between the heat shrinkable cage core capsule enlarged head anchor rod components is defined by the following equations:

[0029] 1. The relationship between the cage core bag assembly and the anchor rod body is defined by the equation:

[0030]

[0031] Where: D e is the effective diameter of the pouch after opening (mm); d r is the diameter of the anchor rod body (mm); h is the distance along the length of the bag (mm); L is the total length of the bag (mm); α is the basic expansion coefficient, ranging from 4.2 to 4.8; β is the fluctuation correction coefficient, ranging from 0.1 to 0.15.

[0032] 2. Spatial distribution relationship equation of circumferential reinforcement and longitudinal connecting reinforcement:

[0033]

[0034] Where: S i is the distance between the ith annular reinforcement and the adjacent annular reinforcement (mm); S0 is the reference distance, which is 150mm; λ is the attenuation coefficient, which ranges from 0.2 to 0.3; i is the serial number of the annular reinforcement; and n is the total number of annular reinforcements.

[0035] 3. The radial positioning rib distribution equation of the buckle carrier:

[0036]

[0037] Where: R jis the length of the jth radial locating rib (mm); R0 is the reference length, which is 40mm; γ is the length variation coefficient, which ranges from 0.05 to 0.1; j is the serial number of the radial locating rib; and m is the total number of radial locating ribs.

[0038] 4. Strength distribution equation of steel plate reinforcement:

[0039]

[0040] Where: T(x) is the thickness of the reinforcement at a distance x from the center point (mm); T0 is the reference thickness at the center point, which is 12 mm; l is the length of the reinforcement (mm); x is the distance along the direction of the reinforcement (mm); μ is the thickness attenuation coefficient, which ranges from 0.002 to 0.003.

[0041] 5. Contact stress distribution equation between spiral reinforcement and anchor rod:

[0042] P(θ)=P0·(1+η·cos(θ))·e -κθ ;

[0043] Where: P(θ) is the contact stress at the rotation angle θ (MPa); P0 is the initial contact stress, which is 20 MPa; η is the stress fluctuation coefficient, which ranges from 0.1 to 0.15; κ is the stress attenuation coefficient, which ranges from 0.01 to 0.02; θ is the rotation angle (rad).

[0044] Parameter acquisition method:

[0045] 1.D e The specific steps are as follows: a) During the grouting process, the grouting pressure value is recorded every 30 seconds; b) The bag opening diameter is calculated according to the pressure-diameter calibration curve; c) The maximum stable diameter value is taken as D e .

[0046] 2.S i The measurement is obtained through the following steps: a) Use a high-precision vernier caliper to measure the spacing between adjacent circumferential steel bars; b) Measure each spacing position 3 times and take the average value; c) Record the serial number i of each position.

[0047] 3.R j The measurement is obtained by the following steps: a) scanning the buckle carrier using a 3D scanner; b) extracting the length data of each radial positioning rib in the 3D model; c) recording the serial number j of each positioning rib.

[0048] 4. T(x) is measured by the following steps: a) Use an ultrasonic thickness gauge to measure the thickness every 10 mm along the direction of the reinforcement; b) Measure each position 3 times and take the average value; c) Record the distance x from the center point.

[0049] 5. P(θ) is measured by the following steps: a) attaching strain gauges to the surface of the spiral rib; b) recording the strain values ​​at different angles during the tightening process; c) calculating the contact stress using the strain-stress conversion formula.

[0050] Equation principle explanation:

[0051] 1. The relationship equation between the cage core bag assembly and the anchor rod body uses a sine function to describe the bag opening shape, taking into account: a) the non-uniform expansion characteristics of the bag during the grouting process; b) the change in the degree of opening caused by the end constraint effect; c) the nonlinear characteristics of the elastic deformation of the material.

[0052] 2. The annular reinforcement distribution equation adopts an exponential decay function, taking into account: a) the stress concentration area requires a denser reinforcement distribution; b) the principle of economical material use; c) the requirement for convenience of construction operation.

[0053] 3. The radial locating rib distribution equation adopts the cosine function, which takes into account: a) the symmetrical distribution requirements of the locating ribs; b) the feasibility of processing and manufacturing; c) the anti-jamming performance during the installation process.

[0054] 4. The rib strength distribution equation is a combination of power function and exponential function, taking into account: a) the distribution law of bending moment; b) the utilization rate of material strength; c) the feasibility of the processing technology.

[0055] 5. The contact stress distribution equation is a composite of the cosine function and the exponential decay function, taking into account: a) the geometric characteristics of the spiral ribs; b) the friction characteristics of the contact surface; c) the transmission law of the preload force.

[0056] Compared with the prior art, the heat shrinkable cage core bag enlarged head anchor rod of the present invention has achieved significant progress in the following aspects:

[0057] 1. The double anti-corrosion layer design greatly improves the corrosion resistance and service life of the anchor in the underground environment, effectively solving the anti-corrosion problem in the existing technology.

[0058] 2. Setting an expandable bladder at the bottom of the hole not only increases the contact area and volume of the anchor body, but also can accurately control the degree of opening of the bladder according to actual conditions, thereby improving the overall bearing performance.

[0059] 3. An adjustable fixing mechanism is set on the top, which can adapt to complex engineering environments and load conditions, greatly improving the stability of the overall structure.

[0060] 4. A single anchor rod can meet the needs of large-span and large-load projects, greatly simplifying the construction process and reducing project costs.

[0061] In summary, the heat-shrinkable cage core bag enlarged head anchor rod proposed in the present invention has achieved remarkable results in solving the key problems in the prior art, and has significantly improved the bearing performance, service life, construction difficulty and economy, providing a more superior solution for foundation reinforcement projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0063] Figure 1 It is a flow chart of a construction method of a heat shrinkable cage core bag enlarged head anchor rod;

[0064] Figure 2 A schematic diagram of an anchor rod used in a heat shrinkable cage core bag enlarged head anchor rod construction method;

[0065] Figure 3 A cross-sectional view of an anchor rod used in a heat shrinkable cage core bag enlarged head anchor rod construction method;

[0066] Figure 4 A schematic diagram of an anchor bag used in a heat shrinkable cage core bag enlarged head anchor construction method;

[0067] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0068] 1. Anchor rod body; 2. Cage core bag belt assembly; 21. Upper locking buckle; 22. Sealing sleeve; 23. Bag body; 24. Cage core frame; 25. Bottom locking piece; 3. Anti-corrosion layer assembly; 4. Buckle bearing assembly; 41. Annular buckle body; 5. Top fixing assembly; 51. Spiral ribs; 52. Steel pad; 53. Positioning nut; 54. Precision tie nut. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0070] like Figure 1-Figure 4 As shown, it is a first embodiment of a heat shrinkable cage core bag enlarged head anchor rod construction method provided by the present invention. In this embodiment, the following steps are included:

[0071] S10, performing anti-corrosion treatment on the anchor rod body, coating the anchor rod body from below the hole to the bag mouth with epoxy asphalt, with a coating thickness of not less than 300 microns, and wrapping the rod body with a heat shrink tube, and evenly heating the heat shrink tube with a hot air gun to shrink and wrap around the rod body;

[0072] S20, assemble the anchor rod, install the buckle bearing body at every 1500 mm interval on the rod body, install the cage core bag at the end of the anchor rod, use the transverse bolt to bite and lock the upper locking buckle sleeve to the anchor rod body, and use the axial bolt to connect and fix the bag cage core with the upper locking buckle;

[0073] S30. After the cushion layer is poured, the positioning is carried out, and the hole positions are marked according to the design drawings. The hole spacing error of the anchor rod in the horizontal and vertical directions is not greater than 100 mm;

[0074] S40, perform drilling operations, the diameter of the drill hole is not less than 160 mm, the diameter of the enlarged hole is not less than 700 mm, the length is not less than 3000 mm, and the water enlargement time is controlled between 35 minutes and 60 minutes;

[0075] S50, lowering the anchor rod, inserting the anchor rod into the hole by means of a manual auxiliary drilling rig, with the end of the rod body no more than 100 mm from the bottom of the hole, and providing a buckle carrier on the rod body at intervals of 1500 mm;

[0076] S60, grouting the bag, using ordinary Portland cement for grouting, the cement slurry bulk density is not less than 1.82, the anchor body 28-day strength is not less than 35 MPa, and the bag opening diameter is monitored by the grouting monitoring instrument to reach the design value;

[0077] S70, 2 hours after the grouting is completed, grouting is performed to inject additional cement slurry into the borehole;

[0078] S80. After the waterproofing of the raft slab is completed and before the raft slab reinforcement is laid, install the spiral reinforcement, positioning nuts, steel pads, and precision nuts;

[0079] S90. Weld steel bars on the steel plate as temporary support, adjust the positioning nuts to keep the steel plate at the same elevation, and weld the horizontal bidirectional reinforcement of the raft slab to the temporary support.

[0080] Among them, in the above technical scheme, step S10 specifically includes: selecting finely rolled steel bars to make the anchor rod body, using professional epoxy asphalt coating equipment to evenly coat the surface of the anchor rod body with epoxy asphalt as an inner anti-corrosion layer, and controlling the thickness of the inner anti-corrosion layer to be not less than 300 microns. After the surface of the epoxy asphalt reaches a surface dry state, the heat shrink tube is put on the outside of the inner epoxy asphalt coating as an outer anti-corrosion layer, and a professional hot air gun is used to reciprocate and heat along the axial direction of the anchor rod body to make the heat shrink tube evenly heated and produce a thermal compression shrinkage effect, ensuring that the heat shrink tube and the inner epoxy asphalt coating fit tightly to form a double anti-corrosion protection structure.

[0081] The specific implementation method is as follows: First, fine-rolled steel bars are selected to make the anchor rod body. Professional epoxy asphalt coating equipment is used to evenly coat the surface of the anchor rod body with epoxy asphalt as the inner anti-corrosion layer. The coating thickness of the inner anti-corrosion layer is controlled to be no less than 300 microns. After the epoxy asphalt surface reaches the surface dry state, the heat shrink tube is installed on the outer side of the inner epoxy asphalt coating as the outer anti-corrosion layer. A professional hot air gun is used to reciprocate and heat along the axial direction of the anchor rod body, so that the heat shrink tube is evenly heated and produces a thermal compression shrinkage effect, ensuring that the heat shrink tube and the inner epoxy asphalt coating are tightly fitted to form a double anti-corrosion protection structure. The purpose of this step is to form a reliable double anti-corrosion layer on the surface of the anchor rod, effectively preventing the anchor rod from corroding in the underground environment, and improving its corrosion resistance and service life.

[0082] Furthermore, in the above technical scheme, step S20 specifically includes: first, a buckle carrier assembly is installed at intervals of 1500 mm along the length direction of the anchor rod body, the buckle carrier assembly is made of high-strength engineering plastic to form an annular buckle body, the inner surface of the annular buckle body is provided with an annular groove with anti-slip patterns, and the outer surface is provided with radial positioning ribs in a star-shaped array, and the ends of the radial positioning ribs are equipped with arc-shaped protective caps; then, the locking buckle, sealing sleeve, bag body, cage core frame and bottom locking piece are installed in sequence at the end of the anchor rod, and the annular locking buckle body and the sealing sleeve are locked and fixed to the anchor rod body by using transverse fixing bolts, the sealing sleeve is made of elastic material to form an interference fit with the rod body, the cage core frame is welded by annular steel bars and longitudinal connecting ribs and is placed inside the bag body, and the bag body is made of flexible waterproof material and fixedly connected to the anchor rod body by the bottom locking piece.

[0083] The specific implementation method is as follows: first, the buckle bearing assembly is installed every 1500 mm along the length direction of the anchor rod body. The buckle bearing assembly is made of high-strength engineering plastic to form an annular buckle body. The inner surface of the annular buckle body is provided with an annular groove with anti-slip patterns, and the outer surface is distributed with radial positioning ribs in a star-shaped array. The ends of each radial positioning rib are equipped with arc-shaped protective caps. Then, the lock buckle, sealing sleeve, bag body, cage core frame and bottom locking piece are installed on the end of the anchor rod in sequence. The annular lock buckle body and the sealing sleeve are locked and fixed on the anchor rod body by transverse fixing bolts, and the sealing sleeve is made of elastic material to form an interference fit with the rod body. The cage core frame is welded by annular steel bars and longitudinal connecting ribs and placed inside the bag body. The bag body is made of flexible waterproof material and is fixedly connected to the anchor rod body through the bottom locking piece. The purpose of this step is to install the cage core bag assembly on the anchor rod body and use the buckle bearing assembly to realize the positioning of the anchor rod body in the drill hole.

[0084] Furthermore, in the above technical scheme, step S30 specifically includes: after the concrete cushion layer is poured and reaches the design strength requirement, the surveying personnel shall lay out and locate the anchor holes according to the marking requirements of the design drawings, use a total station to accurately locate and measure the anchor holes, use white lime to mark the hole positions, and strictly control the horizontal and vertical hole spacing errors of the anchors to be no more than 100 mm. After the measurement is completed, self-inspection shall be carried out and reported to the supervisor for review. Subsequent construction work can only be carried out after approval by the supervisor.

[0085] The specific implementation method is as follows: after the concrete cushion layer is poured and reaches the design strength requirements, the surveyor will lay out the anchor holes according to the marking requirements of the design drawings. The total station is used to accurately locate the anchor holes, and the hole positions are marked with white lime. The hole spacing errors in the horizontal and vertical directions of the anchors are strictly controlled to be no more than 100 mm. After the measurement is completed, self-inspection is carried out and reported to the supervisor for review. Subsequent construction work can only be carried out after approval by the supervisor. The purpose of this step is to accurately locate the anchor holes according to the design requirements and provide a basis for subsequent anchor installation.

[0086] Furthermore, in the above technical scheme, step S40 specifically includes: using professional drilling equipment to carry out hole-forming operations, controlling the borehole diameter to be not less than 160 mm, using a special reaming drill bit to expand the head section for hole expansion construction, the hole diameter is not less than 700 mm, and the length of the reaming section is not less than 3000 mm. Using a clean water punching process to expand the hole, strictly controlling the clean water expansion time between 35 minutes and 60 minutes, and continuously observing the return water situation until the return water color is the same as the clean water color to ensure that the drilling quality meets the design requirements.

[0087] The specific implementation method is: use professional drilling equipment to perform hole forming operations, and control the diameter of the drill hole to be no less than 160 mm. The expansion head section uses a special expansion drill bit for expansion construction, the expansion diameter is no less than 700 mm, and the expansion section length is no less than 3000 mm. Use the clean water punching process for expansion operations, strictly control the clean water expansion time between 35 minutes and 60 minutes, and continue to observe the return water until the color of the return water is the same as the color of the clean water to ensure that the drilling quality meets the design requirements. The purpose of this step is to expand the head section in the pre-drilled hole to provide sufficient space for subsequent anchor installation.

[0088] Furthermore, in the above technical scheme, step S50 specifically includes: construction personnel cooperate with drilling rig equipment to slowly insert the heat shrink cage core bag enlarged head anchor rod along the axial direction of the borehole, strictly control the distance between the end of the anchor rod body and the bottom of the hole to not exceed 100 mm, and focus on observing the gap state between the radial positioning ribs of the snap-on carrier assembly and the borehole wall during the lowering process, and ensure that the radial positioning ribs are not stuck by adjusting the lowering speed and angle, and at the same time use the snap-on carrier assembly to achieve the centering effect of the anchor rod body in the borehole.

[0089] The specific implementation method is as follows: the construction personnel cooperate with the drilling rig equipment to slowly insert the heat shrink cage core capsule enlarged head anchor rod along the axial direction of the borehole, and strictly control the distance between the end of the anchor rod body and the bottom of the hole to not exceed 100 mm. During the lowering process, focus on observing the gap between the radial positioning ribs of the buckle carrier assembly and the borehole wall, and ensure that the radial positioning ribs do not get stuck by adjusting the lowering speed and angle. At the same time, the buckle carrier assembly is used to achieve the centering effect of the anchor rod body in the borehole. The purpose of this step is to slowly insert the pre-assembled heat shrink cage core capsule enlarged head anchor rod into the pre-enlarged borehole, and use the buckle carrier assembly to ensure the stable positioning of the anchor rod in the hole.

[0090] Furthermore, in the above technical scheme, step S60 specifically includes: selecting 42.5 grade ordinary Portland cement to prepare grouting slurry, strictly controlling the bulk density of cement slurry to be not less than 1.82, ensuring through test block test that the 28-day compressive strength of the anchor body is not less than 35 MPa, installing professional grouting monitoring instruments on the grouting pipeline, monitoring the grouting pressure and the bag opening status in real time, and terminating the grouting operation only when the grouting monitor shows that the bag opening diameter has reached the design specified value and the system prompts that the stop conditions have been met.

[0091] The specific implementation method is: 42.5 grade ordinary silicate cement is used to prepare the grouting slurry, the cement slurry bulk density is strictly controlled to be not less than 1.82, and the 28-day compressive strength of the anchor body is ensured to be not less than 35 MPa through the test block test. Professional grouting monitoring instruments are installed on the grouting pipeline to monitor the grouting pressure and the opening state of the bag in real time. The grouting operation can only be terminated when the grouting monitor shows that the bag opening diameter reaches the design value and the system prompts that the stop condition has been reached. The purpose of this step is to use the grouting technology to fully expand the bag, form a reliable anchor body with the pre-drilled hole wall, and improve the overall bearing capacity of the anchor rod.

[0092] Furthermore, in the above technical scheme, step S70 specifically includes: 2 hours after the bag grouting operation is completed, the borehole is supplemented with cement slurry with the same ratio as the bag grouting, and the return grouting at the hole mouth is closely observed during the grouting process. When the color and concentration of the return grouting are basically consistent with the injected slurry, the grouting is stopped to ensure that the grouting fullness meets the design requirements and effectively improves the strength of the anchor body.

[0093] The specific implementation method is as follows: 2 hours after the bag grouting operation is completed, the drill hole is supplemented with cement slurry of the same proportion as the bag grouting. During the grouting process, the grouting at the hole mouth is closely observed. When the color and concentration of the grouting are basically consistent with the injected slurry, the grouting is stopped to ensure that the grouting fullness meets the design requirements and effectively improves the strength of the anchor body. The purpose of this step is to fill the possible gaps in the hole by supplementary grouting, and further improve the overall density of the anchor body.

[0094] Furthermore, in the above technical scheme, step S80 specifically includes: after the raft slab waterproofing construction is completed but before the raft slab steel bars are laid, the top fixing assembly is installed, which includes spiral bars, steel pads, positioning nuts and precision-tied nuts in sequence. The spiral bars adopt a spiral steel bar structure with a pitch of 50 mm and a twisted anti-slip pattern on the surface. The steel pads adopt a square steel plate structure with diagonal reinforcement ribs with a triangular cross-section on the upper surface and positioning bosses distributed in an annular array on the edge of the lower surface. The positioning nuts and precision-tied nuts are adjusted to form a stable locking connection between the components.

[0095] The specific implementation method is as follows: after the waterproof construction of the raft slab is completed but before the raft slab reinforcement is laid, the top fixing assembly is installed. The top fixing assembly includes spiral ribs, steel pads, positioning nuts and precision nuts. The spiral ribs adopt a spiral steel bar structure with a pitch of 50 mm, and a twisted anti-skid pattern is provided on the surface. The steel pad adopts a square steel plate structure, with a through hole matching the anchor rod body in the center, a triangular cross-section reinforcement rib is provided along the diagonal direction on the upper surface, and positioning bosses are distributed in a circumferential array at the edge of the lower surface. The positioning nuts and precision nuts are adjusted to form a stable locking connection between the components. The purpose of this step is to install an adjustable top fixing assembly at the top of the anchor rod to provide a stable support foundation for subsequent raft slab construction.

[0096] Furthermore, in the above technical solution, step S90 specifically includes: using a laser level to project a horizontal elevation control line, maintaining all steel pads in the same elevation plane by precisely adjusting positioning nuts and precision nuts, welding steel bars on the steel pads as temporary support components, and welding and fixing the horizontal bidirectional steel bars of the raft slab to the temporary support after they are in place to form a stable support system; when the design thickness of the raft slab exceeds 1500 mm, adding diagonal bracing components at the temporary support position of the anchor rod to ensure the overall stability of the anchor rod stirrup.

[0097] The specific implementation method is as follows: a laser level is used to project the horizontal elevation control line, and all steel pads are kept in the same elevation plane by accurately adjusting the positioning nuts and precision nuts. Steel bars are welded on the steel pads as temporary support components, and after the horizontal bidirectional steel bars of the raft are in place, they are welded and fixed to the temporary support to form a stable support system. When the design thickness of the raft exceeds 1500 mm, diagonal bracing components are added at the temporary support position of the anchor rod to ensure the overall stability of the anchor rod stirrup. The purpose of this step is to ensure that the anchor rod remains stable during the raft casting and subsequent construction process through the setting of temporary support components to avoid displacement or deformation.

[0098] like Figure 2-Figure 4 As shown, in the above technical solution, the heat shrinkable cage core bag enlarged head includes an anchor rod body 1, the anchor rod body 1 is columnar, the outer surface of the anchor rod body 1 is provided with an anti-corrosion layer component 3, the anti-corrosion layer component 3 is used to protect the anchor rod body 1 from corrosion, and a top fixing component 5 is provided above the anchor rod body 1, and the top fixing component 5 is used for fixing; the outer side wall of the anti-corrosion layer component 3 is provided with a buckle bearing component 4, and the buckle bearing component 4 is used to ensure the center positioning of the anchor rod body in the drill hole, and the bottom of the anchor rod body 1 is provided with a cage core bag belt component 2, and the anchor rod body 1 is used to strengthen the bearing capacity of the anchor rod body 1;

[0099] The cage core bag belt assembly 2 includes an upper locking buckle 21, a sealing sleeve 22, a bag body 23, a cage core frame 24 and a bottom locking piece 25. The sealing sleeve 22 is located at the bottom of the outer wall of the anchor rod body 1 and is an annular structure. It is interference fit with the anchor rod body 1. The sealing sleeve 22 is made of elastic material. The outer wall of the sealing sleeve 22 is provided with an upper locking buckle 21. The upper locking buckle 21 is an annular structure. The inner wall is in close contact with the outer wall of the sealing sleeve 22. The bottom of the sealing sleeve 22 is fixedly connected to the cage core frame 24. The cage core frame 24 includes a plurality of annular steel bars and longitudinal connecting ribs. The annular annular steel bars are evenly arranged along the length direction of the bag body 23. The adjacent annular steel bars are welded and fixed by longitudinal connecting ribs. The bag body 23 is made of flexible waterproof material, and its upper end is fixedly connected to the sealing sleeve 22 and is located outside the cage core frame 24. The lower end of the bag body 23 is fixedly connected to the anchor rod body through a bottom locking piece.

[0100] The anti-corrosion layer assembly 3 is located on the outer side wall of the anchor rod body 1 and is in close contact with the anchor rod body 1. The anti-corrosion layer assembly 3 is two-layered. The inner layer of the anti-corrosion layer assembly 3 is an epoxy asphalt coating, and the outer layer is a heat shrink tube. The inner epoxy asphalt coating is in close contact with the surface of the anchor rod body, and the outer heat shrink tube is coated on the outer surface of the inner epoxy asphalt coating by hot pressing.

[0101] The buckle bearing assembly 4 is located on the outer side wall of the anti-corrosion layer assembly 3, and the buckle bearing assembly 4 is arranged every 1500 mm along the length direction of the anchor rod body. The buckle bearing assembly 4 includes a plurality of annular buckle bodies, and the annular buckle bodies are made of high-strength engineering plastics, and the inner surface thereof is provided with an annular groove matching the outer surface of the anchor rod body, and the annular groove is provided with anti-slip patterns;

[0102] Furthermore, the buckle bearing assembly 4 further includes radial positioning ribs, which are distributed in a star-shaped array on the outer surface of the annular buckle body, and an arc-shaped protective cap is provided at the end of each radial positioning rib to prevent the radial positioning rib from being stuck with the borehole wall during the lowering process;

[0103] The top fixing assembly 5 includes a spiral rib 51, a steel pad 52, a positioning nut 53 and a precision-tied nut 54. The spiral rib 51 is a threaded steel bar, spirally wound around the outer wall of the anchor rod body 1, the inner diameter of the spiral rib 51 matches the outer diameter of the anchor rod body, the pitch of the spiral rib is 50 mm, and the surface of the spiral rib is provided with a twisted anti-skid pattern to enhance the grip with concrete. A precision-tied nut 54 is provided on the top of the spiral rib 51, and a steel pad 52 is provided above the precision-tied nut 54. The steel pad 52 is a square steel plate structure, a through hole matching the anchor rod body is provided in the center, and reinforcing ribs are provided on the upper surface of the steel pad along the diagonal direction. The reinforcing ribs are designed with a triangular cross-section, and the bottom edge is welded and fixed to the upper surface of the steel pad. The pitch of the spiral reinforcement is 50 mm, and the surface of the spiral reinforcement is provided with a twisted anti-skid pattern to enhance the grip between the reinforcement and the concrete; the positioning nut 53 is located above the steel pad 52 and cooperates with the precision nut 54 to fix the steel pad 52.

[0104] In the design of heat shrinkable cage core capsule enlarged head anchor, the relationship equation between multiple key parameters is used to define the coordination performance between the components:

[0105] 1. The relationship between the cage core bag assembly and the anchor rod body is defined by the equation:

[0106]

[0107] Among them, D e is the effective diameter of the pouch after opening (mm), d r is the diameter of the bolt body (mm), h is the distance along the length of the bag (mm), L is the total length of the bag (mm), α is the basic expansion coefficient, ranging from 4.2 to 4.8, and β is the fluctuation correction coefficient, ranging from 0.1 to 0.15. This equation describes the non-uniform expansion characteristics of the bag during the grouting process, and takes into account the end constraint effect and the nonlinear characteristics of the elastic deformation of the material.

[0108] 2. The spatial distribution relationship equation between the annular reinforcement and the longitudinal connecting reinforcement is:

[0109]

[0110] Among them, S i is the spacing between the i-th annular reinforcement and the adjacent annular reinforcement (mm), S0 is the reference spacing, which is 150 mm, λ is the attenuation coefficient, which ranges from 0.2 to 0.3, i is the serial number of the annular reinforcement, and n is the total number of annular reinforcements. This equation uses an exponential attenuation function, taking into account the need for denser reinforcement distribution in stress concentration areas, while taking into account the economic use of materials and the convenience of construction operations.

[0111] 3. The radial positioning rib distribution equation of the buckle carrier is:

[0112]

[0113] Among them, R j is the length of the jth radial locating rib (mm), R0 is the reference length, which is 40 mm, γ is the length variation coefficient, which is in the range of 0.05-0.1, j is the serial number of the radial locating rib, and m is the total number of radial locating ribs. This equation uses the cosine function, taking into account the symmetrical distribution requirements of the locating ribs, the feasibility of processing and manufacturing, and the anti-jamming performance during installation.

[0114] 4. The strength distribution equation of the steel plate reinforcement is:

[0115]

[0116] Among them, T(x) is the thickness of the reinforcement at the distance x from the center point (mm), T0 is the reference thickness at the center point, which is 12mm, l is the length of the reinforcement (mm), x is the distance along the reinforcement direction (mm), and μ is the thickness attenuation coefficient, which ranges from 0.002 to 0.003. This equation uses a power function and an exponential function to combine, taking into account the distribution law of the bending moment, the utilization rate of the material strength, and the feasibility of the processing technology.

[0117] 5. The contact stress distribution equation between the spiral reinforcement and the anchor rod is:

[0118] P(θ)=P0·(1+η·cos(θ))·e -κθ ;

[0119] Among them, P(θ) is the contact stress at the rotation angle θ (MPa), P0 is the initial contact stress, which is 20MPa, η is the stress fluctuation coefficient, which is in the range of 0.1-0.15, κ is the stress attenuation coefficient, which is in the range of 0.01-0.02, and θ is the rotation angle (rad). This equation uses a composite of cosine function and exponential decay function, taking into account the geometric characteristics of the spiral rib, the friction characteristics of the contact surface, and the transmission law of the preload.

[0120] The values ​​of the above key parameters need to be obtained through actual measurement or experiment. e It can be obtained by real-time monitoring of the grouting pressure monitor; S i It can be obtained by measuring the spacing between adjacent annular reinforcements with a vernier caliper and taking the average value; R jThe stress can be obtained by scanning the buckle carrier with a 3D scanner and extracting data from the 3D model; T(x) can be obtained by measuring the thickness along the rib direction with an ultrasonic thickness gauge and taking the average value; P(θ) can be obtained by pasting strain gauges on the surface of the spiral rib, recording the strain values ​​at different angles during the tightening process, and then calculating it using the strain-stress conversion formula.

[0121] The formula variables and constant brightness used in the present invention are shown in Table 1:

[0122] Table 1: Formula constants and variable explanations in the invention

[0123]

[0124]

[0125] A second embodiment of a heat shrinkable cage core bag enlarged head anchor rod construction method provided by the present invention. In this embodiment, a heat shrinkable cage core bag enlarged head anchor rod construction method is provided:

[0126] In a large-scale subway project, due to the complex geological conditions, it is necessary to use heat-shrinkable cage core capsule enlarged head anchor rods to reinforce the foundation. The groundwater level in the area where the project is located is high and the soil layer is weak, which brings great challenges to the construction of the foundation engineering. For this reason, the project adopts the heat-shrinkable cage core capsule enlarged head anchor rod construction method proposed in the present invention.

[0127] First, the anchor rod body is treated for corrosion. Professional epoxy asphalt coating equipment is used to evenly coat the surface of the anchor rod body with 300 microns of epoxy asphalt as the inner anti-corrosion layer. After the epoxy asphalt surface reaches a dry state, the heat shrink tube is put on the outer side of the inner coating as the outer anti-corrosion layer. The construction personnel use a professional hot air gun to reciprocate and heat the heat shrink tube along the axial direction of the anchor rod body, so that the heat shrink tube is evenly heated and produces a heat-compression shrinkage effect, ensuring that the heat shrink tube fits tightly with the inner epoxy asphalt coating to form a double anti-corrosion protection structure.

[0128] Secondly, the anchor rod is assembled. First, the buckle bearing assembly is installed every 1500 mm along the length direction of the anchor rod body. This buckle bearing assembly is made of high-strength engineering plastics and includes an annular buckle body, radial positioning ribs and other components. The inner surface of the annular buckle body is provided with an annular groove matching the outer diameter of the anchor rod body, and the groove is provided with anti-slip patterns; the radial positioning ribs are distributed in a star-shaped array on the outer surface of the annular buckle body, and each positioning rib end is equipped with an arc-shaped protective cap. Then, the upper lock buckle, sealing sleeve, bladder body, cage core frame and bottom locking piece are installed on the end of the anchor rod in sequence. The upper lock buckle consists of an annular lock buckle body and a transverse fixing bolt, which is locked with the sealing sleeve by the transverse bolt and fixed to the anchor rod body. The sealing sleeve is made of elastic material and forms an interference fit with the outer surface of the rod. The bladder body is made of flexible waterproof material, and a cage core frame welded by annular steel bars and longitudinal connecting ribs is provided inside, and the lower end is fixedly connected to the anchor rod body through the bottom locking piece.

[0129] Next, the anchor hole position is laid out and positioned. After the concrete cushion is poured and reaches the design strength, the surveyor uses a total station to accurately position and measure the anchor hole position according to the design drawing requirements. The horizontal and vertical hole spacing errors of the anchor are strictly controlled to be no more than 100 mm, and the hole positions are marked with white lime. After the measurement is completed, self-inspection is carried out, and subsequent construction can only be carried out after review and approval by the supervisor.

[0130] Afterwards, the hole forming operation is carried out. The drilling rig equipment is used to control the diameter of the hole to be no less than 160 mm, and a special hole enlarging drill is used to enlarge the bottom of the hole. The diameter of the hole enlargement is no less than 700 mm, and the length of the hole enlarging section is no less than 3000 mm. The entire hole enlarging operation adopts the clean water punching process, and the clean water enlarging time is strictly controlled between 35 minutes and 60 minutes. The return water is continuously observed until the color is consistent with the clean water to ensure that the drilling quality meets the design requirements.

[0131] Next, the anchor rod is lowered. The construction personnel cooperate with the drilling rig equipment to slowly insert the pre-assembled heat shrink cage core capsule enlarged head anchor rod along the axial direction of the hole. The distance between the end of the anchor rod body and the bottom of the hole is strictly controlled to be no more than 100 mm. During the lowering process, the gap between the radial positioning ribs of the buckle carrier assembly and the hole wall is observed. By adjusting the lowering speed and angle, the positioning ribs are ensured not to be blocked. At the same time, the anchor rod body is centered in the hole with the help of the buckle carrier.

[0132] After that, the bag grouting operation is carried out. Use 42.5 grade ordinary silicate cement to prepare the grouting slurry, strictly control the cement slurry bulk density to be no less than 1.82, and ensure that the 28-day compressive strength of the anchor body is no less than 35 MPa through the test block test. Install professional monitoring instruments on the grouting pipeline to monitor the grouting pressure and the bag opening status in real time. The grouting operation can be terminated only when the monitor shows that the bag opening diameter reaches the design value and the system prompts that the stop condition has been reached.

[0133] Two hours after the bag grouting is completed, the borehole is supplemented with cement slurry of the same proportion as the bag grouting. Closely observe the return slurry at the hole mouth, and stop grouting when the color and concentration of the return slurry are basically the same as the injected slurry to ensure that the grouting fullness meets the design requirements.

[0134] Finally, after the waterproofing construction of the raft slab is completed but before the raft slab reinforcement is laid, the top fixing assembly is installed. First, the spiral reinforcement, steel pad, positioning nut and fine tie nut are installed on the top of the anchor rod body in sequence. The spiral reinforcement adopts a spiral steel bar structure with a pitch of 50 mm and a twist-shaped anti-slip pattern on the surface; the steel pad is a square steel plate structure with a through hole in the center matching the anchor rod, a triangular cross-section reinforcement rib is provided along the diagonal direction on the upper surface, and a positioning boss is distributed in a circumferential array at the edge of the lower surface. By adjusting the positioning nut and the fine tie nut, each component forms a stable locking connection. Then, a laser level is used to control the elevation, accurately adjust each steel pad to the same horizontal plane, and weld steel bars on the steel pad as a temporary support. After the horizontal bidirectional reinforcement of the raft slab is in place, it is welded and fixed to the temporary support to form a stable support system. If the design thickness of the raft slab exceeds 1500 mm, it is also necessary to add a diagonal brace component at the temporary support position of the anchor rod to ensure the overall stability of the stirrup bar.

[0135] In general, the heat shrinkable cage core capsule enlarged head anchor construction method fully utilizes the advantages of various innovative technical measures, effectively solves the problems of existing mechanical enlarged head anchors in terms of corrosion resistance, anchorage, stability, etc., not only improves the quality and reliability of the project, but also simplifies the construction process and reduces the project cost. This method has been successfully applied in large-scale subway projects under complex geological conditions, providing a more superior solution for foundation reinforcement projects.

[0136] A third embodiment of a heat shrinkable cage core bag enlarged head anchor rod construction method provided by the present invention, in this embodiment, provides a specific structure of the heat shrinkable cage core bag enlarged head anchor rod:

[0137] A large highway project needs to reinforce the foundation, and the heat shrinkable cage core bag enlarged head anchor rod proposed in the present invention is used. The anchor rod consists of the following main components:

[0138] 1. Anchor rod body:

[0139] The anchor rod body is made of finely rolled steel bars with a diameter of 32 mm. In order to improve the corrosion resistance, a double anti-corrosion layer is set on the outer surface of the rod, including an inner epoxy asphalt coating and an outer heat shrink tube.

[0140] The inner epoxy asphalt coating is 300 microns thick and is evenly coated on the rod surface by professional coating equipment. After the coating reaches the surface dry state, the heat shrink tube is put on its outer side to form an outer anti-corrosion layer. A professional hot air gun is used to heat along the axial direction of the rod body, so that the heat shrink tube produces a thermal compression shrinkage effect, which fits tightly with the inner epoxy coating and plays an anti-corrosion role together. This double anti-corrosion design can effectively block the corrosive media in the underground environment and greatly increase the service life of the anchor rod.

[0141] 2. Cage core bag assembly:

[0142] The cage core bag assembly is arranged at the bottom end of the anchor rod body, and is composed of an upper locking buckle, a sealing sleeve, a bag body, a cage core frame and a bottom locking piece.

[0143] The upper lock buckle includes an annular lock buckle body and a transverse fixing bolt, which is locked with the sealing sleeve through the transverse bolt and fixed to the upper end of the anchor rod body. The sealing sleeve is made of elastic polyurethane material, and the inner surface is interference fit with the outer diameter form of the anchor rod body, which can effectively seal the space in the hole.

[0144] The bladder body is made of flexible waterproof material made of polyamide, the upper end is fixedly connected to the sealing sleeve, and the inside is provided with a cage core frame welded by circumferential steel bars and longitudinal connecting bars. This cage core frame can not only enhance the rigidity of the bladder body, but also improve the uniformity of slurry distribution during grouting. The lower end of the bladder body is fixedly connected to the anchor rod body through the bottom locking piece.

[0145] During the grouting process, cement slurry enters the bladder, causing it to gradually expand to a preset diameter, thereby forming a reliable anchoring connection with the hole wall. This expandable bladder assembly can not only significantly increase the contact area and volume of the anchor body, but also accurately adjust its opening degree according to actual conditions, further improving the overall load-bearing capacity.

[0146] 3. Buckle carrier assembly:

[0147] The buckle bearing body assembly is arranged every 1500 mm along the length direction of the anchor rod body to ensure the center positioning of the anchor rod in the drill hole.

[0148] The buckle carrier is made of high-strength engineering plastics and includes an annular buckle body and radial positioning ribs. The inner surface of the annular buckle body is provided with an annular groove matching the outer diameter of the anchor rod body, and an annular protrusion with anti-slip patterns is provided in the groove. The radial positioning ribs are distributed in a star-shaped array on the outer surface of the annular buckle body, and an arc-shaped protective cap is installed at the end of each positioning rib to prevent jamming during the lowering process.

[0149] This buckle bearing assembly can be reliably fixed to the anchor rod body, and the anchor rod can be centrally positioned in the hole through the contact between the radial positioning ribs and the hole wall during the lowering process. This is not only conducive to the subsequent grouting operation, but also ensures that the anchor rod maintains a stable stress state when subjected to stress.

[0150] 4. Top fixing components:

[0151] The top fixing assembly is arranged at the top of the anchor rod body, and includes components such as spiral reinforcement, steel pad, positioning nut and precision tie nut.

[0152] The spiral reinforcement adopts a spiral steel bar structure, the inner diameter matches the outer diameter of the anchor rod, the pitch is 50 mm, and the surface is provided with a twist-shaped anti-slip pattern. This special spiral reinforcement structure can form a reliable bite connection with the concrete, enhancing the overall stability between it and the upper structure.

[0153] The steel plate adopts a square steel plate structure, with a through hole in the center matching the anchor rod. The upper surface of the steel plate is provided with a triangular cross-section reinforcement rib along the diagonal direction, and the lower surface edge is provided with a number of positioning bosses distributed in a circumferential array. By adjusting the positioning nut and the precision tie nut, the steel plate can be ensured to remain at the same level, providing stable support for the upper raft.

[0154] In large-span and large-load projects, diagonal bracing components can be added at the temporary support position of the anchor rod. This diagonal bracing component can further improve the stability of the overall structure and ensure that key components such as stirrups will not be displaced or deformed when subjected to force.

[0155] The heat shrinkable cage core bag enlarged head anchor rod of the present invention adopts multiple innovative technical means to solve the key problems in the prior art.

[0156] First, a double anti-corrosion layer design of an inner epoxy asphalt coating and an outer heat shrink tube is used on the surface of the anchor rod. As a high-quality anti-corrosion coating, epoxy asphalt can effectively block the corrosion of corrosive media such as moisture and salt on the anchor rod steel. The heat shrink tube is used as an outer layer of protection. It is wrapped on the epoxy asphalt coating through heat shrinkage, which further enhances the anti-corrosion performance and forms a double barrier. This design not only improves the corrosion resistance of the anchor rod in the underground environment, but also effectively prolongs its service life, thus providing a reliable reinforcement method for foundation engineering.

[0157] Secondly, an expandable bladder assembly is set at the end of the anchor rod. This bladder assembly consists of a locking buckle, a sealing sleeve, a flexible bladder body and a cage core frame. During the grouting process, cement slurry enters the bladder, causing it to gradually expand to a preset diameter, thereby forming a reliable anchoring connection with the hole wall. This not only greatly increases the contact area and volume of the anchor body, but also can accurately control the opening degree of the bladder according to actual conditions, further improving the overall bearing capacity. At the same time, the setting of the cage core frame can also enhance the rigidity of the internal structure of the bladder, ensuring that it will not be deformed or damaged when bearing loads.

[0158] Furthermore, an adjustable fixing mechanism is provided at the top of the anchor rod. This mechanism includes components such as spiral ribs, steel pads, positioning nuts and precision nuts. By adjusting the positioning nuts and precision nuts, it is possible to ensure that the steel pads are maintained at the same horizontal elevation, thereby providing stable support for upper structures such as rafts. At the same time, in large-span and large-load projects, diagonal bracing components can be added to the top of the anchor rod to further improve the stability of the overall structure. This adjustable fixing mechanism can adapt to different engineering environments and load conditions, greatly improving the applicability of the solution of the present invention.

[0159] In addition, compared with the traditional combination of multiple anchor rods, the single anchor rod in the solution of the present invention can meet the needs of large-span and large-load projects. This is because the present invention sets an expandable bladder assembly at the bottom of the hole, which not only increases the contact area and volume of the anchor body, but also can accurately adjust the opening degree of the bladder according to actual conditions, thereby significantly improving the overall bearing capacity of a single anchor rod. This design not only simplifies the construction process and reduces engineering costs, but also improves construction efficiency.

Claims

1. A heat shrinkable cage core bag enlarged head anchor construction method, characterized in that: The following steps are involved: S10, performing anti-corrosion treatment on the anchor rod body, coating the anchor rod body from below the hole to the bag mouth with epoxy asphalt, with a coating thickness of not less than 300 microns, and wrapping the rod body with a heat shrink tube, and evenly heating the heat shrink tube with a hot air gun to shrink and wrap around the rod body; S20, assemble the anchor rod, install the buckle bearing body at every 1500 mm interval on the rod body, install the cage core bag at the end of the anchor rod, use the transverse bolt to bite and lock the upper locking buckle sleeve to the anchor rod body, and use the axial bolt to connect and fix the bag cage core with the upper locking buckle; S30. After the cushion layer is poured, the positioning is carried out, and the hole positions are marked according to the design drawings. The hole spacing error of the anchor bolt in the horizontal and vertical directions is not greater than 100 mm; S40, perform hole-forming operation, the diameter of the drill hole shall not be less than 160 mm, the diameter of the hole expansion section shall not be less than 700 mm, the length shall not be less than 3000 mm, and the water hole expansion time shall be controlled between 35 minutes and 60 minutes; S50, lowering the anchor rod, inserting the anchor rod into the hole by means of a manual auxiliary drilling rig, with the end of the rod body no more than 100 mm from the bottom of the hole, and providing a buckle carrier on the rod body at intervals of 1500 mm; S60, grouting the bag, using ordinary Portland cement for grouting, the cement slurry bulk density is not less than 1.82, the anchor body 28-day strength is not less than 35 MPa, and the bag opening diameter is monitored by the grouting monitoring instrument to reach the design value; S70, 2 hours after the grouting is completed, grouting is performed to inject additional cement slurry into the borehole; S80. After the waterproofing of the raft slab is completed and before the raft slab reinforcement is laid, install the spiral reinforcement, positioning nuts, steel pads, and precision nuts; S90. Weld steel bars on the steel plate as temporary support, adjust the positioning nuts to keep the steel plate at the same elevation, and weld the horizontal bidirectional reinforcement of the raft slab to the temporary support.

2. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 1, characterized in that: The step S10 specifically includes: carefully selecting finely rolled steel bars to form an anchor rod body, using professional epoxy asphalt coating equipment to evenly coat the surface of the anchor rod body with epoxy asphalt as an inner anti-corrosion layer, controlling the thickness of the inner anti-corrosion layer to be no less than 300 microns, and after the epoxy asphalt surface reaches a surface dry state, putting a heat shrink tube on the outer side of the inner epoxy asphalt coating as an outer anti-corrosion layer, using a professional hot air gun to reciprocate and heat along the axial direction of the anchor rod body, so that the heat shrink tube is evenly heated and produces a thermal compression shrinkage effect, ensuring that the heat shrink tube and the inner epoxy asphalt coating are tightly fitted to form a double anti-corrosion protection structure.

3. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 2, characterized in that: The step S20 specifically includes: first, installing a buckle bearing body assembly at intervals of 1500 mm along the length direction of the anchor rod body, the buckle bearing body assembly is made of high-strength engineering plastic to form an annular buckle body, the inner surface of the annular buckle body is provided with an annular groove with anti-slip patterns, and the outer surface is provided with radial positioning ribs in a star-shaped array, and the ends of the radial positioning ribs are equipped with arc-shaped protective caps; then, the locking buckle, sealing sleeve, bag body, cage core frame and bottom locking piece are installed in sequence at the end of the anchor rod, and the annular locking buckle body and the sealing sleeve are locked and fixed to the anchor rod body by transverse fixing bolts, the sealing sleeve is made of elastic material to form an interference fit with the rod body, the cage core frame is welded by annular steel bars and longitudinal connecting ribs and is placed inside the bag body, and the bag body is made of flexible waterproof material and fixedly connected to the anchor rod body by the bottom locking piece.

4. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 3, characterized in that: The step S30 specifically includes: after the concrete cushion layer is poured and reaches the design strength requirement, the surveying personnel will lay out and locate the anchor holes according to the marking requirements of the design drawings, use a total station to accurately locate and measure the anchor holes, use white lime to mark the hole positions, and strictly control the horizontal and vertical hole spacing errors of the anchors to be no more than 100 mm. After the measurement is completed, self-inspection will be carried out and reported to the supervisor for review. Subsequent construction work can only be carried out after approval by the supervisor.

5. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 4, characterized in that: The step S40 specifically includes: using professional drilling equipment to perform hole-forming operations, controlling the drill diameter to be no less than 160 mm, using a special reaming drill bit to expand the head section, the reaming diameter is no less than 700 mm, and the reaming section length is no less than 3000 mm, using a clean water punching process to expand the hole, strictly controlling the clean water expansion time between 35 minutes and 60 minutes, and continuously observing the return water until the return water color is the same as the clean water color, to ensure that the drilling quality meets the design requirements.

6. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 5, characterized in that: The step S50 specifically includes: the construction personnel cooperate with the drilling rig equipment to slowly insert the heat shrink cage core bag enlarged head anchor rod along the axial direction of the borehole, strictly control the distance between the end of the anchor rod body and the bottom of the hole to not exceed 100 mm, and focus on observing the gap state between the radial positioning ribs of the buckle carrier assembly and the borehole wall during the lowering process, and ensure that the radial positioning ribs are not stuck by adjusting the lowering speed and angle, and at the same time use the buckle carrier assembly to achieve the centering effect of the anchor rod body in the borehole.

7. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 6, characterized in that: The step S60 specifically includes: selecting 42.5 grade ordinary Portland cement to prepare grouting slurry, strictly controlling the cement slurry bulk density to be not less than 1.82, ensuring the 28-day compressive strength of the anchor body to be not less than 35 MPa through test block tests, installing professional grouting monitoring instruments on the grouting pipeline, and monitoring the grouting pressure and the bag opening status in real time. The grouting operation can be terminated only when the grouting monitor shows that the bag opening diameter has reached the design specified value and the system prompts that the stop conditions have been met.

8. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 7, characterized in that: The step S70 specifically includes: 2 hours after the bag grouting operation is completed, supplementary grouting is performed on the borehole using cement slurry with the same ratio as the bag grouting, and the return grouting at the hole mouth is closely observed during the grouting process. When the color and concentration of the return grouting are basically consistent with the injected slurry, the grouting is stopped to ensure that the grouting fullness meets the design requirements and effectively improves the strength of the anchor body.

9. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 8, characterized in that: The step S80 specifically includes: after the raft slab waterproofing construction is completed but before the raft slab steel bars are laid, installing the top fixing assembly, which includes spiral bars, steel pads, positioning nuts and precision nuts in sequence, wherein the spiral bars adopt a spiral steel bar structure with a pitch of 50 mm and a twisted anti-skid pattern on the surface, the steel pads adopt a square steel plate structure with diagonal reinforcement bars with a triangular cross-section on the upper surface and positioning bosses distributed in an annular array at the edge of the lower surface, and the positioning nuts and precision nuts are adjusted to form a stable locking connection between the components.

10. A heat shrinkable cage core bag enlarged head anchor construction method according to claim 9, characterized in that: The step S90 specifically includes: using a laser level to project a horizontal elevation control line, maintaining all steel pads in the same elevation plane by accurately adjusting positioning nuts and precision nuts, welding steel bars on the steel pads as temporary support members, and welding and fixing the horizontal bidirectional steel bars of the raft slab to the temporary support after they are in place to form a stable support system; when the design thickness of the raft slab exceeds 1500 mm, adding diagonal bracing members at the temporary support position of the anchor rod to ensure the overall stability of the anchor rod stirrup.

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