Retreating type hollow grouting anchor cable and construction method thereof

Abstract

The invention relates to a retreating type hollow grouting anchor cable and a construction method thereof. The hollow grouting anchor cable comprises a hollow spiral anchor rod formed by winding a steel strand; the anchor head assembly is arranged at one end of the hollow rotating rod body and used for stretching into the bottom of a hole for anchoring; the grout outlet is formed in the anchor head assembly; the locking assembly is arranged at the other end of the hollow rotating rod body and is used for locking and fixing the end part of the hole; the grouting assembly comprises a grouting pipe capable of movably stretching into the hollow spiral anchor rod and a grouting device connected with the end of the grouting pipe. Compared with the prior art, compared with a traditional hollow grouting anchor cable, due to the fact that a fixed hollow grouting pipe is not arranged, the anchor cable can be bent, construction is convenient, and economical efficiency is more reasonable under the conditions that a long drill hole is formed and the working face of a roadway is narrow. The defects that a grouting pipe is prone to being damaged, construction is limited, and cost is high can be effectively overcome, and the grouting pipe is suitable for deep well soft rock roadways, large-deformation surrounding rock and narrow working environments.

Description

Technical Field

[0001] The present invention relates to the technical field of mining anchor cables, in particular to a backward hollow grouting anchor cable and a construction method thereof. Background Art

[0002] Hollow grouting anchor cables enable full-length anchoring and grouting reinforcement of surrounding rock, making them widely used in coal mine roadway support. Traditional hollow grouting anchor cables, due to their internal hollow grouting steel tubes, are inflexible and prone to deformation and even breakage. This makes construction in some narrow coal mine roadway working surfaces, where longer anchor cables are required for reinforcement, inconvenient and may require segmented installation or the use of specialized equipment, increasing the number of steps and complexity, and thus, costs. Furthermore, in fractured surrounding rock, grouting the entire length in a single pass can be difficult to control.

[0003] Patent publication number CN103016034A discloses a hollow grouting anchor cable for mining, comprising a hollow spiral rod body formed by winding steel strands. A rigid grouting pipe and a flexible grouting pipe are connected within the rod body. A support sleeve is positioned between the rod body and the flexible grouting pipe, which is fitted over the flexible grouting pipe. The flexible grouting pipe has a set of grouting holes. A threaded locking sleeve is positioned at one end of the rod body corresponding to the rigid grouting pipe. The locking sleeve is fitted with a tray, and the locking sleeve also has a self-aligning nut that engages with the tray. The rigid grouting pipe has external threads at both ends, with one end exposed outside the rod body and the other end connected to one end of the flexible grouting pipe. A solid metal rod is positioned within the rod body corresponding to the other end of the flexible grouting pipe. However, the fixed position of the support sleeve may restrict the slurry flow path. If the steel strands are not fully extended or the rock formation is dense, the slurry will preferentially flow out of the proximal grouting holes, leaving insufficient grouting at the distal end, thus affecting the deep surrounding rock reinforcement effect. Furthermore, the grouting pipes use rigid and flexible connections, which may result in connection problems and grouting pressure loss. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art such as the fragility of grouting pipes, limited construction and high cost, and to provide a retreatable hollow grouting anchor cable and its construction method, which is suitable for deep well soft rock tunnels, large deformation surrounding rocks and narrow working environments.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In one aspect, the present invention provides a retractable hollow grouting anchor cable, comprising:

[0007] A hollow spiral anchor made of wound steel strands;

[0008] An anchor head assembly provided at one end of the hollow rotating rod body and used to extend into the bottom of the hole for anchoring;

[0009] A slurry outlet provided on the anchor head assembly;

[0010] A locking assembly provided at the other end of the hollow rotating rod body and used for locking and fixing the end of the hole;

[0011] The invention also provides a grouting assembly for grouting, comprising a grouting pipe which can be moved into the interior of the hollow spiral anchor rod, and a grouting device connected to the end of the grouting pipe.

[0012] Furthermore, the anchor head assembly comprises:

[0013] a first hollow threaded steel pipe connected to the hollow rotating rod;

[0014] and an anchor head provided at the end of the first hollow threaded steel pipe.

[0015] Furthermore, the first hollow threaded steel pipe is provided with an external thread, and the end of the hollow spiral anchor rod connected to the first hollow threaded steel pipe is provided with an internal thread. The first hollow threaded steel pipe is threadedly connected to the hollow rotating rod body, thereby increasing the friction between the first hollow threaded steel pipe and the steel strand and preventing the steel strand from sliding.

[0016] Furthermore, there are a plurality of slurry outlets, which are axially arranged on the side of the hollow threaded steel pipe to improve the effect of the initial anchoring of the anchor head.

[0017] Furthermore, the locking assembly includes:

[0018] a second hollow threaded steel pipe connected to the hollow rotating rod;

[0019] and an anchor sleeved on the outside of the second hollow threaded steel pipe.

[0020] Furthermore, the second hollow threaded steel pipe is provided with an external thread, the end of the hollow spiral anchor rod connected to the second hollow threaded steel pipe is provided with an internal thread, and the second hollow threaded steel pipe is threadedly connected to the hollow rotating rod body, thereby increasing the friction between the second hollow threaded steel pipe and the steel strand and preventing the steel strand from sliding.

[0021] Furthermore, the anchor includes an anchor plate and a locking piece, the second hollow threaded steel pipe passes through the anchor plate, the locking piece is threadedly connected to the second hollow threaded steel pipe, and the end surface of the anchor plate is in close contact with the locking piece.

[0022] Furthermore, a slurry stopper is provided between the hollow spiral anchor rod and the anchor.

[0023] Furthermore, the hollow spiral anchor includes a steel strand and a hollow spiral channel formed by winding the steel strand. Without setting a hollow grouting steel pipe in the hollow spiral anchor, the anchor can be bent in places where a long anchor cable is needed but the tunnel working surface is relatively narrow, facilitating construction.

[0024] In another aspect, the present invention further provides a construction method for a retreatable hollow grouting anchor cable, comprising the following steps:

[0025] S1, drilling holes in the rock mass;

[0026] S2, assembling the hollow spiral anchor rod, anchor head assembly, and locking assembly to obtain a hollow grouting anchor cable;

[0027] S3 inserting the grouting pipe into the interior of the hollow spiral anchor rod and extending it to a position close to or reaching the anchor head assembly;

[0028] S4. Place an anchoring agent at the bottom of the borehole, insert the hollow grouting anchor cable inserted into the grouting pipe into the borehole, and anchor the anchor head assembly to the bottom of the borehole through the anchoring agent;

[0029] S5. Connect the grouting device to the grouting pipe port exposed outside the drill hole;

[0030] S6, pumping slurry into the grouting pipe through the grouting device and out of the slurry outlet, first filling and sealing the deepest area of ​​the borehole, ensuring that the slurry in the deepest area of ​​the borehole is filled, withdrawing the grouting pipe toward the outer end of the borehole, and the grouting process continues. When the slurry is full, stop grouting and completely pull out the grouting pipe;

[0031] S7, after the slurry reaches a certain strength, applying prestress through the locking assembly;

[0032] S8. The slurry in the borehole solidifies, forming an integral reinforcement structure between the hollow spiral anchor and the surrounding rock mass, and the process is completed.

[0033] Furthermore, in step S6, the grouting pipe is retreated in sections, and the structure of the hollow grouting anchor cable adopts a section-type hollow grouting anchor cable, which adopts a conventional technical structure in the field. The present invention can be used in combination with the section-type hollow grouting anchor cable to illustrate the wide range of application scenarios of the hollow grouting anchor cable of the present invention. This does not involve the innovation of the present invention and is not elaborated on.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) Compared with traditional hollow grouting anchor cables, the present invention does not have a fixed hollow grouting pipe. In the case of long boreholes and narrow tunnel working surfaces, the anchor cable can be bent, which facilitates construction and is more economical. It can effectively solve the defects of grouting pipe fragility, construction restrictions, and high costs. It is suitable for deep well soft rock tunnels, large deformation surrounding rock, and narrow working environments.

[0036] (2) The "backward" grouting of the present invention avoids to the greatest extent the problems that may occur in the "forward" grouting (injection from the hole mouth to the bottom of the hole), such as the grouting pipe being blocked, the front slurry solidifying too quickly to block the slurry path, or the air being trapped in the hole to form gaps. It ensures that the slurry fills the entire borehole continuously and evenly from the bottom of the hole to the hole mouth. The anchor head is fully wrapped and anchored by the first slurry injected, and the entire rod body is wrapped by the subsequent slurry to form "full-length bonding", and the stress state is more uniform. The slurry continues to penetrate the surrounding rock cracks during the withdrawal process, and the reinforcement range is larger.

[0037] (3) Grouting and pipe pulling are carried out simultaneously in the present invention, which simplifies the operation process and is convenient to operate.

[0038] (4) The hollow spiral rod body wrapped with the steel strand of the present invention and the integral grouting bonding provide excellent tensile and shear resistance.

[0039] (5) The present invention has strong adaptability and is particularly suitable for broken zones, loose bodies, and poor rock formations with high water seepage, because early sealing of the hole bottom and segmented grouting can effectively prevent slurry loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of the hollow grouting anchor cable shown in Example 1;

[0041] Figure 2 Schematic diagram of the structure of the hollow spiral anchor shown in Example 1;

[0042] Figure 3 is a cross-sectional view of the hollow spiral anchor shown in Example 1;

[0043] Figure 4 This is a schematic structural diagram of the first hollow threaded steel pipe shown in Example 1;

[0044] Figure 5 This is a schematic structural diagram of the second hollow threaded steel pipe shown in Example 1.

[0045] Description of the marks in the figure:

[0046] 1-Hollow spiral anchor, 11-Steel strand, 12-Hollow spiral channel;

[0047] 2-anchor head assembly, 21-first hollow threaded steel pipe 1, 22-anchor head;

[0048] 3-locking assembly, 31-second hollow threaded steel pipe, 32-anchor, 321-anchor plate, 322-locking piece, 33-slurry stopper;

[0049] 4- grouting assembly, 41- grouting pipe, 42- grouting device;

[0050] 5-Slurry outlet. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments are based on the technical solutions of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. In the following embodiments or examples, unless otherwise specified, functional components or structures are conventional components or conventional structures used in the art to achieve the corresponding functions.

[0052] It should be noted that in the description of the present invention, the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0054] Example 1

[0055] A retreating hollow grouting anchor cable, such as Figures 1 to 3 As shown, including:

[0056] A hollow spiral anchor rod 1 formed by winding a steel strand 11;

[0057] An anchor head assembly 2 provided at one end of the hollow rotating rod body 1 and used to extend into the bottom of the hole for anchoring;

[0058] A slurry outlet 5 provided on the anchor head assembly 2;

[0059] A locking assembly 3 provided at the other end of the hollow rotating rod body 1 and used for locking and fixing the end of the hole;

[0060] The grouting assembly 4 for grouting includes a grouting pipe 41 that can be moved into the interior of the hollow spiral anchor 1 and a grouting device 42 connected to the end of the grouting pipe 41 .

[0061] In this embodiment, the anchor head assembly 2 includes:

[0062] A first hollow threaded steel pipe 21 connected to the hollow rotating rod body 1;

[0063] and an anchor head 22 provided at the end of the first hollow threaded steel pipe 21 .

[0064] In this embodiment, if Figure 4 As shown, the first hollow threaded steel pipe 21 is provided with an external thread, and the end of the hollow spiral anchor rod 1 connected to the first hollow threaded steel pipe 21 is provided with an internal thread. The first hollow threaded steel pipe 21 is threadedly connected to the hollow rotating rod body 1, thereby increasing the friction between the first hollow threaded steel pipe 21 and the steel strand 11 to prevent the steel strand 11 from sliding.

[0065] In this embodiment, there are a plurality of slurry outlets 5 axially arranged on the side of the hollow threaded steel pipe 21 to improve the effect of the initial anchoring of the anchor head 22 .

[0066] In this embodiment, the locking assembly 3 includes:

[0067] A second hollow threaded steel pipe 31 connected to the hollow rotating rod body 1;

[0068] and an anchor 32 sleeved on the outside of the second hollow threaded steel pipe 31 .

[0069] In this embodiment, if Figure 5 As shown, the second hollow threaded steel pipe 31 is provided with an external thread, and the end of the hollow spiral anchor rod 1 connected to the second hollow threaded steel pipe 31 is provided with an internal thread. The second hollow threaded steel pipe 31 is threadedly connected to the hollow rotating rod body 1, thereby increasing the friction between the second hollow threaded steel pipe 31 and the steel strand 11 to prevent the steel strand 11 from sliding.

[0070] In this embodiment, the anchor 32 includes an anchor plate 321 and a locking member 322. The second hollow threaded steel pipe 31 passes through the anchor plate 321. The locking member 322 is threadedly connected to the second hollow threaded steel pipe 31. The end surface of the anchor plate 321 is in close contact with the locking member 322. The locking member 322 can be a nut, and the specific type can be selected according to actual conditions.

[0071] In this embodiment, a grout stopper 33 is provided between the hollow spiral anchor rod 1 and the anchor 32 .

[0072] In this embodiment, the hollow spiral anchor 1 includes a steel strand 11 and a hollow spiral channel 12 formed by winding the steel strand 11. Without setting a hollow grouting steel pipe in the hollow spiral anchor 1, the anchor cable can be bent to facilitate construction in places where longer anchor cable support is required but the tunnel working surface is relatively narrow.

[0073] A construction method for a retreating hollow grouting anchor cable comprises the following steps:

[0074] S1. Drill a hole in the rock mass with a diameter slightly larger than the diameter of the anchor rod.

[0075] S2. Assemble the hollow spiral anchor rod 1, the anchor head assembly 2, and the locking assembly 3 to obtain a hollow grouting anchor cable.

[0076] S3 inserts the grouting pipe 41 into the interior of the hollow spiral anchor 1 and extends it to approach or reach the first hollow threaded steel pipe 21 and is located near the grout outlet 5.

[0077] S4. Put a quick anchoring agent at the bottom of the borehole, send the hollow grouting anchor cable inserted into the grouting pipe 41 into the borehole, and anchor the anchor head assembly 2 at the bottom of the borehole through the anchoring agent. When the hollow grouting anchor cable is inserted, the hollow spiral anchor rod 1 breaks the quick anchoring agent and mixes it, and quickly solidifies near the anchor head assembly 2 to provide initial anchoring force.

[0078] S5. Connect the grouting device 42 to the port of the grouting pipe 41 exposed outside the borehole.

[0079] S6. The slurry is pumped into the grouting pipe 41 through the grouting device 42 and flows out from the slurry outlet 5. First, the deepest area of ​​the borehole is filled and sealed. After ensuring that the slurry in the deepest area of ​​the borehole is filled, the grouting pipe 41 is slowly and evenly withdrawn toward the outer end of the borehole. At this time, the grouting process continues, and the space left by the grouting pipe 41 is immediately filled with the continuously injected slurry. Driven by the pumping pressure of the grouting device 42, the injected slurry not only fills the annular space between the borehole and the hollow spiral anchor rod 1, but also penetrates into the surrounding relatively broken or cracked rock mass, forming a larger range of reinforcement. The hollow spiral anchor rod 1 formed by winding the steel strands 11 not only provides a high-strength core, but its spiral structure can guide the slurry to flow along the rod body of the hollow spiral anchor rod 1 during the grouting process, and allows the slurry to penetrate outward through the gaps between the strands, which helps to form a more uniform wrapping effect. When the slurry is full, stop grouting and completely pull out the grouting pipe 41. The slurry eventually fills the entire borehole length and the space of the second hollow threaded steel pipe 21, and stops grouting when it overflows from the orifice or reaches the predetermined grouting amount and pressure, indicating that the borehole is full.

[0080] S7. After the slurry reaches a certain strength, prestress is applied to the second hollow threaded steel pipe 31 through the anchor 32, tensioning the steel strand 11. The anchor 32 is finally locked to the anchor plate 321, placing the entire anchor system in an active tension state, exerting compression constraint on the surrounding rock and improving the support effect. The connection between the second hollow threaded steel pipe 31 and the hollow spiral anchor 1 ensures effective transmission of tension.

[0081] S8. The grout in the borehole solidifies, bonding the hollow spiral anchor rod 1 to the surrounding rock mass tightly, continuously, and three-dimensionally into an integral reinforcement structure. The anchor head assembly 2 is also firmly anchored at the bottom of the hole.

[0082] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A backward hollow grouting anchor cable, characterized in that: include: A hollow spiral anchor rod (1) formed by winding a steel strand (11); An anchor head assembly (2) provided at one end of the hollow rotating rod body (1) and used to extend into the bottom of the hole for anchoring; A slurry outlet (5) provided on the anchor head assembly (2); A locking assembly (3) provided at the other end of the hollow rotating rod (1) and used for locking and fixing the end of the hole; And a grouting assembly (4) for grouting, comprising a grouting pipe (41) that can be moved into the interior of the hollow spiral anchor rod (1), and a grouting device (42) connected to the end of the grouting pipe (41).

2. A retreat type hollow grouting anchor cable according to claim 1, characterized in that: The anchor head assembly (2) comprises: a first hollow threaded steel pipe (21) connected to the hollow rotating rod body (1); and an anchor head (22) arranged at the end of the first hollow threaded steel pipe (21).

3. A retreat type hollow grouting anchor cable according to claim 2, characterized in that: The first hollow threaded steel pipe (21) is provided with an external thread, one end of the hollow spiral anchor rod (1) connected to the first hollow threaded steel pipe (21) is provided with an internal thread, and the first hollow threaded steel pipe (21) is threadedly connected to the hollow rotating rod body (1).

4. The backward hollow grouting anchor cable according to claim 2, characterized in that: There are a plurality of slurry outlets (5) which are axially arranged on the side of the hollow threaded steel pipe (21).

5. The backward hollow grouting anchor cable according to claim 1, characterized in that: The locking assembly (3) comprises: a second hollow threaded steel pipe (31) connected to the hollow rotating rod (1); and an anchor (32) sleeved on the outside of the second hollow threaded steel pipe (31).

6. The backward hollow grouting anchor cable according to claim 5, characterized in that: The second hollow threaded steel pipe (31) is provided with an external thread, and one end of the hollow spiral anchor (1) connected to the second hollow threaded steel pipe (31) is provided with an internal thread, and the second hollow threaded steel pipe (31) is threadedly connected to the hollow rotating rod body (1).

7. The backward hollow grouting anchor cable according to claim 5, characterized in that: The anchor (32) comprises an anchor plate (321) and a locking piece (322); the second hollow threaded steel pipe (31) passes through the anchor plate (321); the locking piece (322) is threadedly connected to the second hollow threaded steel pipe (31); and the end surface of the anchor plate (321) is in close contact with the locking piece (322).

8. The backward hollow grouting anchor cable according to claim 5, characterized in that: A slurry stopper (33) is provided between the hollow spiral anchor rod (1) and the anchor (32).

9. The backward hollow grouting anchor cable according to claim 1, characterized in that: The hollow spiral anchor rod (1) comprises a steel strand (11) and a hollow spiral channel (12) formed by winding the steel strand (11).

10. A construction method for a retreatable hollow grouting anchor cable according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, drilling holes in the rock mass; S2, assembling the hollow spiral anchor rod (1), the anchor head assembly (2), and the locking assembly (3) to obtain a hollow grouting anchor cable; S3 inserting the grouting pipe (41) into the interior of the hollow spiral anchor (1) and extending it to a position close to or reaching the anchor head assembly (2); S4, placing an anchoring agent at the bottom of the borehole, inserting the hollow grouting anchor cable inserted into the grouting pipe (41) into the borehole, and anchoring the anchor head assembly (2) at the bottom of the borehole through the anchoring agent; S5, connecting the grouting device (42) to the port of the grouting pipe (41) exposed outside the borehole; S6, pumping slurry from the grouting pipe (41) through the grouting device (42) and flowing out from the slurry outlet (5), first filling and sealing the deepest area of ​​the borehole, ensuring that the slurry in the deepest area of ​​the borehole is filled, and then withdrawing the grouting pipe (41) toward the outer end of the borehole. At this time, the grouting process continues. When the slurry is full, the grouting is stopped and the grouting pipe (41) is completely withdrawn; S7, after the slurry reaches a certain strength, applying prestress through the locking assembly (3); S8, the slurry in the borehole solidifies, and the hollow spiral anchor (1) and the surrounding rock mass form an integral reinforcement structure, and the process is completed.

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