A method for constructing a pressure-bearing combined capsule anchor rod

Abstract

This invention relates to the field of construction, specifically to a method for constructing a pressure-bearing composite chamber anchor bolt, comprising the following steps: S1, locating drilling points in the soil layer; S2, drilling holes in the soil layer; S3, placing the anchor bolt into the drilled hole; S4, grouting the chamber of the anchor bolt to expand it, and grouting into the drilled hole; S5, after grouting, applying prestress to the anchor bolt; S6, completing the construction. This invention can calculate the optimal prestress locking value applied to the anchor bolt under different working conditions during anchor bolt construction, thereby maximizing the strength and durability of the anchor bolt.

Description

Technical Field

[0001] This invention relates to the field of construction, specifically a method for constructing pressure-bearing combined capsule anchor bolts. Background Technology

[0002] Anchor bolts are used for anchor support, a reinforcement and support method employed in surface engineering projects such as slopes and deep foundation pits, as well as underground chamber construction such as tunnels and mining areas. They are constructed using metal, wood, polymer, or other materials, and driven into pre-drilled holes in the surface rock or the surrounding rock mass. Utilizing the special structure of the head and body of the bolt, and the tail support plate (which may be omitted), or relying on bonding, the anchor bolts combine the surrounding rock with the stable rock mass to create a suspension effect, a composite beam effect, or a reinforcement effect, thus achieving the purpose of support. Anchor bolts not only provide good support but also save materials, simplify construction, facilitate mechanized operation, and allow for fast construction speed. One end of the anchor bolt connects to the engineering structure, while the other end extends into the ground. The entire anchor bolt is divided into a free section and an anchored section. The free section is the area where the tension at the anchor head is transferred to the anchored body; its function is to apply prestress to the anchor bolt.

[0003] During anchor bolt construction, prestress is often applied to improve the anchor bolt's strength and durability. However, there is currently no research on how to adjust the prestress locking value of the anchor bolt to maximize its strength and durability for different construction conditions. Furthermore, existing anchor bolts, as described in patent number "CN116575448A," include an outer sleeve and an inner anchor bolt. The outer sleeve is fitted and threaded onto the outside of the inner anchor bolt. The inner anchor bolt includes a rod body and a drill bit, with grouting holes penetrating both the rod body and the drill bit along its length. The problem with this existing technology is that, due to axial grouting, the grouting speed is affected by the hole diameter, resulting in a slow grouting rate. Additionally, solid matter in the grout easily clogs the long and narrow grouting holes, causing production interruptions. Therefore, a solution is urgently needed. Summary of the Invention

[0004] To avoid and overcome the technical problems existing in the prior art, this invention provides a method for constructing pressure-bearing combined chamber anchor bolts. This invention can calculate the optimal prestress locking value applied to the anchor bolts under different working conditions during anchor bolt construction, thereby maximizing the strength and durability of the anchor bolts.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for constructing a pressure-bearing composite chamber anchor bolt includes the following steps:

[0007] S1. Locate the drilling points in the soil layer;

[0008] S2. Drilling holes for soil layer construction;

[0009] S3. Insert the anchor bolt into the borehole;

[0010] S4. Grout the anchor bolt's chamber to expand it, and grout into the borehole.

[0011] S5; After grouting is completed, prestress is applied to the anchor bolts during tensioning. The prestress locking value σ of the anchor bolts is... 锁 for:

[0012] σ 锁 =σ 损 +σ con

[0013] Where, σ 损 This represents the sum of all prestress losses in the anchor bolt;

[0014]

[0015] Where 'a' represents the inward contraction value of the anchor bolt tensioning end;

[0016] E s This indicates the elastic modulus of the anchor bolt.

[0017] l represents the distance from the tensioning end of the anchor bolt to the anchoring end;

[0018] e represents the Euler number;

[0019] κ represents the friction coefficient of local deviations in the borehole channel;

[0020] x represents the borehole length in the soil layer;

[0021] μ represents the coefficient of friction between the anchor bolt and the borehole.

[0022] θ represents the sum of the angles between the tensioning end of the anchor bolt and the tangent of the borehole.

[0023] σ pc This represents the normal compressive stress in the concrete at the resultant point of the tension zone of the anchor bolt;

[0024] f represents the compressive strength of the grouting concrete when prestressing is applied;

[0025] ρ represents the reinforcement ratio in the tension zone of the anchor bolt;

[0026] σ con This indicates the anti-buoyancy tension of the anchor bolt;

[0027] σ con =0.793f pyk

[0028] f pyk This indicates the yield strength of the anchor bolt;

[0029] S6; Construction completed.

[0030] As a further aspect of the present invention: the minimum cross-sectional area A of the anchor rod is:

[0031]

[0032] Among them, K t Represents an empirical constant;

[0033] f y Indicates the design strength of the anchor bolt;

[0034] Q represents the pull-out safety factor of the anchor body of the anchor bolt;

[0035] T represents the ultimate pull-out force of the anchor bolt;

[0036] The ultimate pull-out force T of the anchor bolt is:

[0037] T=πD1L d f1+πD2L D f2+π(D2 2 -D1 2 )P D / 4

[0038] Where D1 represents the length of the anchorage section of the anchor bolt;

[0039] L d Indicates the diameter of the anchorage section of the anchor bolt;

[0040] f1 represents the bond strength between the grout in the anchoring section of the anchor bolt and the stratum;

[0041] D2 represents the diameter of the anchor chamber;

[0042] L D Indicates the length of the anchor bolt's bladder;

[0043] f2 represents the bond strength between the grout in the capsule and the formation;

[0044] P D This represents the resistance strength of the soil acting on the end face of the capsule;

[0045]

[0046] Wherein, K0 represents the coefficient of static earth pressure of the soil at the front end of the capsule;

[0047] h represents the thickness of the soil covering the capsule;

[0048] γ represents the weight of the soil covering the capsule;

[0049] K P This represents the passive earth pressure coefficient of the soil at the front end of the capsule;

[0050] τ represents the lateral pressure coefficient when the capsule undergoes vertical displacement;

[0051] C represents the standard value of cohesion of the soil at the front end of the capsule.

[0052] As a further embodiment of the present invention: a sleeve is coaxially fixed at the bottom of the anchor rod, both the upper and lower ends of the sleeve are closed, the inner wall of the sleeve and the anchor rod enclose an annular cavity for grout flow, a grouting joint communicating with the annular cavity is arranged on the sleeve, the grouting pipe forms a detachable fit with the grouting joint along the direction parallel to the anchor rod, and a grout discharge port is also provided on the sleeve so that the grout is injected into the cavity of the bladder after passing through the grouting pipe, the grouting joint, the annular cavity and the grout discharge port in sequence.

[0053] As a further embodiment of the present invention: the grouting joint is elbow-shaped, and the grouting pipe and the vertical section of the grouting joint form a threaded fit.

[0054] As a further aspect of the present invention: the position of the grout outlet corresponds to the position of the bottom end of the chamber, so that the grouting fills the chamber cavity from bottom to top, and a one-way grouting valve is installed on the grout outlet.

[0055] As a further aspect of the present invention: at least two sets of discharge ports are arranged, with the spacing between adjacent discharge ports gradually increasing from bottom to top.

[0056] As a further embodiment of the present invention: the length of the capsule corresponds to the length of the sleeve, and the top and bottom ends of the anchor rod are respectively provided with an anchoring top plate and an anchoring bottom plate for positioning the anchor rod. A locking nut that is threaded with the anchor rod is provided on the anchor rod, and the sleeve is clamped and locked by the locking nut and the anchoring bottom plate.

[0057] As a further embodiment of the present invention: both the anchoring top plate and the anchoring bottom plate are steel reinforcement anchoring plates, and the contact surface between the locking nut and the sleeve is sealed by a rubber gasket.

[0058] As a further embodiment of the present invention: the top of the anchor rod extends above the concrete pad, and a water-stop rubber ring is arranged on the contact surface between the anchor rod and the concrete pad.

[0059] As a further aspect of the present invention: the anchor rod is provided with centering bearings at intervals on the rod body between the sleeve and the concrete pad, the centering bearings are arranged in a conical shape that is wider at the top and narrower at the bottom, and the centering bearings are threadedly engaged with the anchor rod; the anchor rod is a threaded steel bar, and a PE pipe is heat-shrinkably fixed on the rod body between the anchor rod and the concrete pad, and the gap between the PE pipe and the anchor rod is filled with anti-corrosion grease; the outer ring of the anchor rod is provided with a spiral stirrup arranged coaxially below the concrete pad.

[0060] Compared with the prior art, the beneficial effects of the present invention are:

[0061] 1. This invention establishes a formula for the prestress locking value of anchor bolts, and introduces calculations to determine the optimal prestress locking value applied to anchor bolts under different working conditions, thereby maximizing the strength and durability of anchor bolts, improving anchoring force, and reducing anchor bolt deformation and displacement. After the anchor bolt structure is redesigned according to this invention, the minimum cross-sectional area of ​​the anchor bolt after shortening the sleeve length can be obtained through calculation. The anchor bolt can meet the set ultimate pull-out force requirements under this cross-sectional area.

[0062] 2. This invention features a grouting pipe arranged parallel to the anchor bolt on its side and a shortened casing length. Grout is injected into the annular gap between the casing and the anchor bolt through the external grouting pipe, allowing the grout to drain from the discharge port at the bottom of the casing into the bladder cavity, thereby expanding the bladder. The external grouting pipe significantly improves the grouting speed and is less prone to clogging. Even if clogging occurs, the grouting pipe can be replaced immediately to avoid affecting construction. It has low cost, is easy to disassemble and assemble, and effectively improves construction efficiency.

[0063] 3. The present invention features an elbow-type grouting connector, which facilitates the assembly and disassembly of the grouting pipe. The arrangement of the one-way grouting valve avoids grout backflow. By setting multiple grout discharge ports and reasonably adjusting the spacing between adjacent grout discharge ports, the grouting speed can be greatly accelerated and the grouting efficiency can be improved.

[0064] 4. This invention significantly shortens the sleeve length so that its length corresponds only to the length of the chamber, reducing costs. The sleeve can be fixed by the cooperation of the locking nut and the anchoring base plate.

[0065] 5. This invention achieves anchor bolt alignment through the cooperation of multiple centering bearings. By heat-shrinking and fixing PE pipes on the anchor bolt body and filling the gaps with anti-corrosion grease, the service life of the anchor bolt is effectively improved. Attached Figure Description

[0066] Figure 1 This is a structural schematic diagram of the pressure-bearing combined capsule anchor bolt of the present invention.

[0067] In the picture:

[0068] 1. Anchor bolt; 11. Anchoring top plate; 12. Water-stopping rubber ring;

[0069] 13. Locking nut; 14. Anchoring base plate; 15. Centering load-bearing body;

[0070] 2. Sleeve; 21. Grouting joint; 22. One-way grouting valve; 23. Chamber; 24. Grouting pipe;

[0071] 3. Concrete foundation Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Please see Figure 1 In this embodiment of the invention, a method for constructing a pressure-bearing composite chamber anchor bolt is provided.

[0074] Includes the following steps:

[0075] S1. Locate the drilling points in the soil layer;

[0076] S2. Drilling holes for soil layer construction;

[0077] S3. Insert anchor rod 1 into the borehole;

[0078] S4. Grout the bladder of anchor bolt 1 to expand the bladder, and grout into the borehole;

[0079] S5; After grouting is completed, prestress is applied to anchor bolt 1 by tensioning, and the prestress locking value σ of anchor bolt 1 is... 锁 for:

[0080] σ 锁 =σ 损 +σ con

[0081] Where, σ 损 This represents the sum of all prestress losses in anchor bolt 1;

[0082]

[0083] Where 'a' represents the inward contraction value of the tensioning end of anchor bolt 1;

[0084] E s This represents the elastic modulus of anchor bolt 1;

[0085] l represents the distance from the tensioning end to the anchoring end of anchor bolt 1;

[0086] e represents the Euler number;

[0087] κ represents the friction coefficient of local deviations in the borehole channel;

[0088] x represents the borehole length in the soil layer;

[0089] μ represents the coefficient of friction between anchor bolt 1 and the borehole.

[0090] θ represents the sum of the angles between the tensioning end of anchor bolt 1 and the tangent of the borehole duct;

[0091] σ pc This represents the normal compressive stress in the concrete at the resultant force point of the tension zone of anchor bolt 1.

[0092] f represents the compressive strength of the grouting concrete when prestressing is applied;

[0093] ρ represents the reinforcement ratio of the tension zone of anchor bolt 1;

[0094] σ con This indicates the anti-buoyancy tension of anchor bolt 1;

[0095] σ con =0.793f pyk

[0096] f pyk This indicates the yield strength of anchor bolt 1;

[0097] S6; Construction completed.

[0098] Because this invention significantly shortens the sleeve length, the structure of the anchor rod 1 changes compared to existing structures. Given that the ultimate pull-out force of the anchor rod 1 is T, the minimum cross-sectional area A of the anchor rod 1 is:

[0099]

[0100] Among them, K t Represents an empirical constant;

[0101] f y Indicates the design strength of anchor bolt 1;

[0102] Q represents the pull-out safety factor of the anchor body of anchor bolt 1;

[0103] T represents the ultimate pull-out force of anchor bolt 1;

[0104] The ultimate pull-out force T of anchor bolt 1 is:

[0105] T=πD1L d f1+πD2L D f2+π(D2 2 -D1 2 )P D / 4

[0106] Where D1 represents the length of the anchoring section of anchor bolt 1;

[0107] L d This indicates the diameter of the anchoring section of anchor bolt 1;

[0108] f1 represents the bond strength between the grout of anchor bolt 1 and the stratum;

[0109] D2 represents the diameter of the capsule of anchor bolt 1;

[0110] L D This indicates the length of the capsule of anchor bolt 1;

[0111] f2 represents the bond strength between the grout in the capsule and the formation;

[0112] P D This represents the resistance strength of the soil acting on the end face of the capsule;

[0113]

[0114] Wherein, K0 represents the coefficient of static earth pressure of the soil at the front end of the capsule;

[0115] h represents the thickness of the soil covering the capsule;

[0116] γ represents the weight of the soil covering the capsule;

[0117] K P This represents the passive earth pressure coefficient of the soil at the front end of the capsule;

[0118] τ represents the lateral pressure coefficient when the capsule undergoes vertical displacement;

[0119] C represents the standard value of cohesion of the soil at the front end of the capsule.

[0120] Anchor rod 1 is inserted vertically into a pre-drilled vertical channel. An anchoring top plate 11 and anchoring bottom plate 14 are respectively arranged at the top and bottom of anchor rod 1 for fixing anchor rod 1. Anchor rod 1 is preferably a threaded steel bar, and anchoring top plate 11 and anchoring bottom plate 14 are preferably steel bar anchoring plates.

[0121] A sleeve 2 is coaxially fixed to the bottom of the anchor bolt 1. The fixing method between the sleeve 2 and the anchor bolt 1 is not limited; welding or threaded fixing are both acceptable. A locking nut 13, which is threadedly engaged with the anchor bolt 1, is coaxially arranged above the sleeve 2. The bottom of the sleeve 2 abuts against the anchor base plate 14, and the top of the sleeve 2 is locked and fixed by the locking nut 13. To improve the sealing, a rubber gasket is arranged on the contact surface between the sleeve 2 and the locking nut 13.

[0122] The inner diameter of the sleeve 2 is larger than the diameter of the anchor rod 1, so that the sleeve 2 and the anchor rod 1 form an annular cavity. The top and bottom of the sleeve 2 are tapered to prevent grout leakage. The upper part of the sleeve 2 has an integrally formed elbow-shaped grouting joint 21, and the grouting pipe 24 is detachably connected to the grouting joint 21 from top to bottom along the vertical direction. The chamber 23 is arranged on the outer ring of the sleeve 2, corresponding to the height of the sleeve 2. The grouting joint 21 can pass through the chamber 23 and connect to the grouting pipe 24, or the grouting joint 21 can be arranged above the chamber 23 and offset from the position of the chamber 23.

[0123] The top and bottom of the chamber 23 are fixed to the sleeve 2 and sealed together. Several grout discharge ports are provided at the bottom of the sleeve 2, corresponding to the bottom of the chamber 23, so that the grout from the sleeve 2 can fill the chamber 23 from bottom to top. Preferably, the spacing between the grout discharge ports gradually increases from bottom to top, and each grout discharge port is equipped with a one-way grouting valve 22 to prevent grout backflow.

[0124] The top of the anchor rod 1 extends above the concrete pad 3. The anchor rod 1 is located on the sleeve 2 and the concrete pad 3, with conical bearing elements 15 arranged at intervals, wider at the top and narrower at the bottom. These bearing elements 15 center the anchor rod 1, and are threadedly connected to it. A PE pipe is also heat-shrinkably fixed to the anchor rod 1 on the sleeve 2 and the concrete pad 3, and the gap between the PE pipe and the anchor rod 1 is filled with anti-corrosion grease.

[0125] A water-stop rubber ring 12 is arranged on the contact surface between the anchor rod 1 and the concrete pad 3, and a spiral stirrup is arranged coaxially on the outer ring of the anchor rod 1 below the concrete pad 3.

[0126] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0127] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

Claims

1. A method for constructing a pressure-bearing composite chamber anchor bolt, characterized in that, Includes the following steps: S1. Locate the drilling points in the soil layer; S2. Drilling holes for soil layer construction; S3. Insert the anchor rod (1) into the borehole; S4. Grout the bladder of the anchor bolt (1) to expand the bladder, and grout into the borehole; S5; After grouting is completed, prestress is applied to the anchor rod (1) by tensioning; S6; Construction completed; An anchor rod (1) is coaxially fixed with a sleeve (2). Both ends of the sleeve (2) are closed. The inner wall of the sleeve (2) and the anchor rod (1) form an annular cavity for grouting flow. A grouting joint (21) communicating with the annular cavity is arranged on the sleeve (2). The grouting pipe (24) is detachably connected with the grouting joint (21) in the direction parallel to the anchor rod (1). A grout discharge port is also provided on the sleeve (2) so that the grouting can be injected into the cavity of the chamber (23) after passing through the grouting pipe (24), the grouting joint (21), the annular cavity and the grout discharge port in sequence. The length of the capsule (23) corresponds to the length of the sleeve (2). The top and bottom ends of the anchor rod (1) are respectively provided with an anchoring top plate (11) and an anchoring bottom plate (14) for positioning the anchor rod (1). A locking nut (13) that is threaded with the anchor rod (1) is provided on the anchor rod (1). The sleeve (2) is clamped and locked by the locking nut (13) and the anchoring bottom plate (14).

2. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 1, characterized in that, The grouting joint (21) is elbow-shaped, and the grouting pipe (24) and the vertical section of the grouting joint (21) form a threaded fit.

3. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 1, characterized in that, The position of the grout outlet corresponds to the bottom position of the chamber (23) so that the grouting fills the chamber (23) from bottom to top. A one-way grouting valve (22) is installed on the grout outlet.

4. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 3, characterized in that, There are at least two sets of discharge outlets, with the spacing between adjacent discharge outlets gradually increasing from bottom to top.

5. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 1, characterized in that, Both the top anchor plate (11) and the bottom anchor plate (14) are steel anchor plates, and the contact surface between the locking nut (13) and the sleeve (2) is sealed by a rubber gasket.

6. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 1, characterized in that, The top of the anchor rod (1) extends above the concrete pad (3), and a water-stop rubber ring (12) is arranged on the contact surface between the anchor rod (1) and the concrete pad (3).

7. The construction method for a pressure-bearing combined chamber anchor bolt according to claim 1, characterized in that, The anchor rod (1) is located between the sleeve (2) and the concrete pad (3) with centering bearings (15) arranged at intervals on the rod body. The centering bearings (15) are arranged in a conical shape with a wider top and a narrower bottom. The centering bearings (15) are threaded with the anchor rod (1). The anchor rod (1) is a threaded steel bar. The anchor rod (1) is located between the sleeve (2) and the concrete pad (3) with a PE pipe that is heat-shrinkable and fixed. The gap between the PE pipe and the anchor rod (1) is filled with anti-corrosion grease. The outer ring of the anchor rod (1) is coaxially arranged with spiral stirrups located below the concrete pad (3).

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