A double-pipe expansion extrusion yielding bolt

Abstract

The present invention relates to a double-tube expansion and extrusion type pressure-yielding anchor rod, which belongs to the field of anchoring and supporting. It includes an anchoring section, a free section and a pressure-yielding member. The pressure-yielding member is composed of an expansion tube, an extrusion tube, a hollow cone, a connecting member and a force-bearing tube. The end of the force-bearing tube is connected to the free section rod body through a thread. The end of the free section rod body is an anchor head with an enlarged diameter. The outer diameter of the anchor head has a circle of slurry holes. The anchor rod body is a hollow structure and can be pressurized for grouting. The slurry flows out from the slurry holes at the anchor head. The pressure-yielding member squeezes the inner and outer double tube walls through the hollow cone to generate a large friction resistance. While providing continuous and constant resistance, the rod body moves forward to achieve the purpose of pressure-yielding. The present invention has a simple structure, and the connections are all threaded connections. It is easy to construct, can provide continuous and constant resistance, has a stable and reliable structure, and meets the requirements of rapid on-site construction.

Description

Technical Field

[0001] The invention belongs to the field of anchoring and supporting, and in particular relates to a double-tube expansion and extrusion type pressure-yielding anchor rod. Background Art

[0002] Anchor bolting technology is an engineering technique that embeds anchor rods into rock and soil to a certain depth to increase its strength and maintain its stability. The reinforcement mechanisms of anchor bolting can be categorized as suspension, composite beams, reinforcement, internal pressure, rock shell, support, and pinning. Anchor bolting offers low cost, fast action, and excellent support effectiveness, making it widely used in mining, transportation, water conservancy, municipal engineering, and other underground engineering fields.

[0003] Engineering practice has shown that traditional anchor failures typically manifest in the following ways: first, the anchor body breaks or shears due to its limited deformation capacity; second, the anchor and anchoring agent pull apart; third, the anchor body separates from the surrounding rock, and there are also damage to the external anchor tray and nut. These failure behaviors are more pronounced in support projects within soft rock, deeply buried rheological rock masses, and deep-buried rock burst and impact pressure zones. To address these failure issues of traditional anchors, researchers have designed a new type of anchor, the yield anchor, that can adapt to large deformations of the surrounding rock and provide sustainable support resistance.

[0004] Yield anchors, also known as extendable anchors, pressure-relieving anchors, energy-absorbing anchors, and stress-relieving anchors, feature high strength and high elongation. They exhibit the ability to slide or extend in response to surrounding rock deformation and rapidly respond to external loads. These properties have made yield anchors an effective solution for supporting and preventing disasters in weak surrounding rock, deeply buried rheological rock masses, and rockburst zones, and have garnered widespread attention since their introduction.

[0005] In recent years, with the continuous advancement of mining technology, mining efforts have intensified, and underground depths have increased. Rock formations in tunnels are subject to varying degrees of impact, causing significant deformation. When surrounding rock undergoes significant deformation, traditional anchors, due to their low elongation, struggle to meet the support requirements of modern mines. To accommodate large rock deformation, increasing the elongation of the anchor cable and the load capacity of the anchor are crucial for supporting large deformations in tunnel surrounding rock. Developing a yield anchor that increases both the elongation and bearing capacity of the anchor has become a pressing issue. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a double-tube expansion and extrusion type pressure-yielding anchor rod, which utilizes the diameter difference between the hollow cone and the tube body. When the hollow cone is forced to move, it squeezes the tube wall to generate huge friction resistance, offsetting the energy generated by the deformation of the surrounding rock while the anchor rod produces large deformation, solving the problems of low elongation and inconsistent resistance provided by traditional anchor rods (ropes). On the basis of the existing technology, the present invention adds an extrusion tube to realize the simultaneous extrusion of the double sleeves by the cone, making the pressure-yielding structure more stable. At the same time, the present invention forms a protective layer inside and outside the anchor rod by grouting the hollow anchor rod body, which greatly extends the service life of the anchor rod and improves the stability of the anchor rod.

[0007] The technical solution adopted in the present invention is as follows:

[0008] A double-tube expansion and extrusion type pressure-releasing anchor bolt, comprising an anchoring section, a free section and a pressure-releasing member, characterized in that: the pressure-releasing member comprises an expansion tube, an extrusion tube, a hollow cone, a force-bearing tube and a connecting member; the expansion tube and the extrusion tube are connected to the connecting member through end threads, the inner wall diameter of the expansion tube is larger than the outer wall diameter of the extrusion tube, there is a gap between the two tubes and the two tubes are on the same axis; the expansion tube comprises an expansion section, a section to be expanded, and an outer tail clamp, and the extrusion tube comprises an extrusion section, a section to be extruded, and an inner tail clamp; one end of the connecting member is a hollow threaded rod, and the other end is a hollow cylinder, the outer ring wall of the hollow cylinder has a thread, which is adapted to the end thread of the expansion tube, and the inner ring wall has a thread, which is adapted to the end thread of the expansion tube. The end of the extruded tube is threaded and adapted to connect and fix the pressure-releasing member; the middle part of the hollow cone is a hollow frustum, the hollow part of the hollow frustum is an inverted frustum, one end of the hollow cone is a connecting thread for connecting the stressed tube, and the other end is a hollow cylinder, which serves as the main stress-bearing part of the hollow cone and is mainly used for extrusion and deformation of the tube wall; the hollow cone and the stressed tube are connected and combined into a whole, the outer wall diameter of the stressed tube is smaller than the inner wall diameter of the section to be expanded, and the inner wall diameter of the stressed tube is larger than the outer wall diameter of the section to be extruded, to ensure that the stressed tube can slide freely in the gap formed by the expansion tube and the extruded tube, the diameter of the hollow cylinder at the end of the hollow cone is equal to the diameter of the expansion section and larger than the diameter of the section to be expanded, and the hollow diameter of the end of the hollow cone is equal to the diameter of the expansion section and larger than the diameter of the section to be expanded. The diameter of the extrusion section is smaller than the diameter of the section to be extruded, so that there is a diameter difference between the hollow cone and the tube body; after the hollow cone and the stressed tube are connected, they are placed in the hollow inside of the expansion tube, and the extrusion tube is placed in the hollow inside of the hollow cone and the stressed tube, and the stressed tube is connected to the free section rod body through a thread; when the rock mass is deformed, the anchor rod body is subjected to axial tension, and the stressed rod transmits the force to the hollow cone, causing the hollow cone to have a forward movement trend. Since the inner wall diameter of the section to be expanded in front of the hollow cone is smaller than the diameter of the hollow cylinder at the end of the hollow cone, when the hollow cone passes through the section to be expanded, the inner wall of the expansion tube is squeezed, the tube body expands, the diameter of the tube body increases, the hollow cone moves forward, and the anchor rod undergoes a large deformation shape, while consuming the energy released by the deformation of the external surrounding rock. Similarly, when the hollow cone passes through the section to be extruded, the outer wall of the extrusion tube is squeezed by the hollow cone, the tube body is compressed, the diameter of the tube body is reduced, the hollow cone moves forward, the anchor rod is greatly deformed, and the energy released by the deformation of the external surrounding rock is consumed. The end of the free section rod body is an anchor head with an enlarged diameter. The outer diameter of the anchor head has a circle of grouting holes. The anchor rod body is a hollow structure and can be pressurized grouting. The anchor tail part includes a pad, a fastening bolt, and a wedge-shaped grouting plate. There is a reserved hole in the middle of the pad and the wedge-shaped grouting plate, which can pass through the hollow threaded rod at one end of the connecting component and be fixed by a fastening bolt. The wedge-shaped grouting plate prevents the slurry from flowing out of the anchor hole during grouting.

[0009] Furthermore, the expansion tube and the extrusion tube have the same length, and the inner wall of the expansion tube and the outer wall of the extrusion tube are provided with tiny threads or protrusions to increase friction.

[0010] Furthermore, the outer wall diameter of the hollow cylinder at the end of the hollow cone is 1-3 mm larger than the inner wall diameter of the expansion tube to be expanded, and the inner wall diameter of the hollow cylinder is 1-3 mm smaller than the outer wall diameter of the extrusion tube to be extruded.

[0011] Furthermore, the wall of the outer tail end clamping tube gradually thickens inwardly until the minimum inner wall radius is the same as the outer wall radius of the stressed tube, and this wall thickness is maintained to extend 20mm-40mm in the axial direction. The wall of the inner tail end clamping tube gradually thickens outwardly until the maximum outer wall radius is the same as the inner wall radius of the stressed tube, and this wall thickness is maintained to extend 20mm-40mm in the axial direction, to prevent the hollow cone from being pulled out of the pressure-releasing component and causing the anchor rod to fail, and at the same time prevent external water from entering the pressure-releasing component.

[0012] Furthermore, the diameter of the slurry discharge hole is 20-30 mm, and the number of slurry discharge holes around the expanded diameter anchor head is 5-8.

[0013] Furthermore, the anchor rod bodies are all hollow tubes, and grouting can be performed from the grouting port, and the slurry flows out from the slurry discharge hole.

[0014] Furthermore, the hollow cone and the stress-bearing tube are connected by threads, and can also be welded or integrally formed in a factory.

[0015] Beneficial effects of the present invention:

[0016] The effects and advantages of the present invention are simple structure, all the connections are threaded connections, construction is convenient, and it can provide continuous and constant resistance. Different from the existing technology in which the cone squeezes a single casing, the present invention adds a casing on the basis of the existing technology to achieve the simultaneous squeezing of the double casing by the cone, making the pressure structure more stable, and the resistance generated when squeezing the double casing is stronger, which can adapt to a variety of complex geological conditions. The anchor rod is a hollow structure as a whole, and pressure grouting can be carried out to reduce construction steps and speed up construction. The slurry inside and outside the anchor rod forms a protective layer, which greatly extends the service life of the anchor rod. The structure is stable and reliable, meeting the requirements of rapid on-site construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the double-tube expansion and extrusion type pressure-yielding anchor structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of the anchor rod after compression deformation;

[0019] Figure 3 for Figure 1 Section 1-1;

[0020] Figure 4 This is a schematic diagram of the outer shape of the pressure member;

[0021] Figure 5 Schematic diagram of the connection between the hollow cone and the stress-bearing tube;

[0022] Figure 6 Schematic diagram of the hollow cone shape;

[0023] Figure 7 Schematic diagram of the decomposition of a hollow cone.

[0024] In the figure, 1 is the grouting port; 2 is the fastening nut; 3 is the pad; 4 is the wedge-shaped slurry stopper; 5 is the expansion pipe; 5-1 is the expansion section; 5-2 is the section to be expanded; 5-3 is the outer tail clamp; 6 is the connecting member; 6-1 is the hollow threaded rod; 6-2 is the outer wall thread; 6-3 is the inner wall thread; 7 is the hollow cone; 7-1 is the connecting thread; 7-2 is the hollow frustum; 7-3 is the hollow cylinder; 7-4 is the hollow diameter; 8 is the stressed pipe; 9 is the extrusion pipe; 9-1 is the extrusion section; 9-2 is the section to be extruded; 9-3 is the inner tail clamp; 10 is the hollow pipe; 11 is the free section of the rod; 12 is the slurry discharge port; 13 is the expanded diameter anchor head; DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and embodiments:

[0026] Example:

[0027] like Figure 1-Figure 2As shown, a double-tube expansion and extrusion type pressure-releasing anchor rod comprises an anchoring section, a free section and a pressure-releasing member, characterized in that: the pressure-releasing member comprises an expansion tube (5), an extrusion tube (9), a hollow cone (7), a force-bearing tube (8), and a connecting member (6); the expansion tube (5) comprises an expansion section (5-1), a section to be expanded (5-2), and an outer tail end clamp (5-3); the extrusion tube (9) comprises an extrusion section (9-1), a section to be extruded (9-2), and an inner tail end clamp (9-3); the expansion tube (5) and the extrusion tube (9) are both connected to the connecting member (6) through end threads, the inner wall diameter of the expansion tube (5) is larger than the outer wall diameter of the extrusion tube (9), and there is a gap between the two tubes. The two tubes are on the same axis; one end of the connecting member (6) is a hollow threaded rod (6-1), and the other end is a quasi-hollow cylinder; the outer ring wall (6-2) of the quasi-hollow cylinder has a thread, which is adapted to the thread at the end of the expansion tube (5); the inner ring wall (6-3) has a thread, which is adapted to the thread at the end of the extrusion tube (9), and is used to connect and fix the pressure-releasing member; the outer wall diameter of the hollow cylinder (7-3) at the end of the hollow cone (7) is equal to the inner wall diameter of the expansion section (5-1), which is larger than the inner wall diameter of the section to be expanded (5-2); the hollow diameter of the end of the hollow cone is equal to the outer wall diameter of the extrusion section (9-1), which is smaller than the outer wall diameter of the section to be extruded (9-2), so that the hollow cone ( 7) and the tube body, and the inner wall of the expansion section (5-2) and the outer wall of the extrusion section (9-2) are provided with tiny threads or protrusions to increase friction; the outer tail end clamp (5-3) tube wall gradually thickens inwardly, so that the minimum radius of the inner wall of the outer tail end clamp (5-3) is the same as the radius of the outer wall of the force-bearing tube (8); the inner tail end clamp (9-3) tube wall gradually thickens outwardly, so that the maximum radius of the outer wall of the inner tail end clamp (9-3) is the same as the radius of the inner wall of the force-bearing tube (8), thereby preventing the hollow cone from being pulled out of the pressure-releasing component and causing the anchor rod to fail, and at the same time preventing external water from entering the interior of the pressure-releasing component; after the hollow cone (7) and the force-bearing tube (8) are connected, the expansion tube (5) is placed in the hollow interior, and the pressure-releasing component is squeezed. The tube (9) is placed in the hollow interior of the hollow cone (7) and the load-bearing tube (8), and the load-bearing tube (8) is connected to the free section rod body (11) through a thread; the end of the free section rod body (11) is an anchor head (13) with an enlarged diameter, and the outer diameter of the anchor head has a circle of slurry discharge holes (12); the anchor rod body is a hollow structure and can be pressurized grouting; the anchor tail part includes a pad (3), a fastening bolt (2), and a wedge-shaped slurry-stopping plate (4); there is a reserved hole in the middle of the pad (3) and the wedge-shaped slurry-stopping plate (4), which can pass through the hollow threaded rod (6-1) at one end of the connecting component (6) and be fixed by the fastening bolt (2); the wedge-shaped slurry-stopping plate (4) prevents slurry from flowing out of the anchor hole during grouting.

[0028] like Figure 3As shown, the outer wall diameter of the stressed tube (8) is smaller than the inner wall diameter of the expansion tube (5), and the inner wall diameter of the stressed tube (8) is larger than the outer wall diameter of the extrusion tube (9), thereby ensuring that the stressed tube (8) can slide freely in the gap formed by the expansion tube (5) and the extrusion tube (9). At the same time, during grouting, the slurry is injected from the grouting port (1), passes through the hollow pipe (10), and flows out from the slurry discharge hole (12).

[0029] like Figure 4-7 As shown, the middle part of the hollow cone (7) is a hollow cone (7-2), the hollow part of the hollow cone (7-2) is an inverted cone, one end of the hollow cone (7) is a connecting thread (7-1) for connecting the stress-bearing tube, and the other end is a hollow cylinder (7-3), which serves as the main stress-bearing part of the hollow cone (7) and is mainly used for squeezing and deforming the tube wall; when the rock mass is deformed, the anchor rod body is subjected to axial tension, and the stress-bearing rod transmits the force to the hollow cone (7), so that the hollow cone (7) has a forward movement trend. Since the inner wall diameter of the section to be expanded (5-2) in front of the hollow cone (7) is small, the anchor rod body is subjected to axial tension, and the stress-bearing rod transmits the force to the hollow cone (7), so that the hollow cone (7) has a forward movement trend. The diameter of the hollow cone (7) at the bottom is the largest. When the hollow cone (7) passes through the section to be expanded (5-2), the inner wall of the section to be expanded (5-2) is squeezed, the tube body expands, the diameter of the tube body increases, the hollow cone (7) moves forward, the anchor rod is greatly deformed, and the energy released by the deformation of the external surrounding rock is consumed. Similarly, when the hollow cone (7) passes through the section to be squeezed (9-2), the outer wall of the squeeze tube (9) is squeezed by the hollow cone (7), the tube body is compressed, the diameter of the tube body decreases, the hollow cone (7) moves forward, the anchor rod is greatly deformed, and the energy released by the deformation of the external surrounding rock is consumed.

[0030] The present invention is described below in conjunction with a specific construction process: a hole is drilled at a point with a drilling rig, the diameter of the hole being slightly larger than the diameter of the enlarged diameter anchor head (13), the drilling rig is withdrawn after reaching a predetermined depth, the drill bit is replaced for re-drilling, the re-drilling diameter being slightly larger than the diameter of the expansion tube (5) of the pressure-releasing member, the re-drilling depth being the depth of the pressure-releasing member, i.e., the location of the outer tail end clamp (5-3), the drilling rig is removed, the hole is cleaned with a blower, and the depth and width of the anchor hole are checked to see if they meet the requirements.

[0031] The extruded tube (9) is passed through the hollow cone (7) and connected to the connecting member (6) through a thread. The stressed tube (8) is passed through the extruded tube (9) along the inner tail end clamp (9-3), and the stressed tube (8) is connected to the hollow cone (7) through a thread. Finally, the expansion tube (5) is passed through the stressed tube (8) and connected to the connecting member (6) through a thread at the end of the expansion section (5-1), thereby completing the assembly of the compression member.

[0032] The end of the free section rod body (11) is connected to the enlarged diameter anchor head (13), and the force-bearing tube (8) is connected to the free section rod body (11) through threads, and the anchor rod main body is assembled.

[0033] One end of the anchor head (13) with an enlarged diameter of the anchor rod is slowly fed into the anchor hole. After reaching the bottom of the anchor hole, the anchor rod position is checked to see if it meets the requirements. The wedge-shaped grouting plate (4) is passed through the hollow threaded rod (6-1) and fixed. The pad (3) is fixed at the corresponding position. Grouting is carried out along the grouting port (1) by a grouting machine, and the grout flows out from the grouting hole (12) through the hollow pipe (10) until the anchor hole is filled.

[0034] 3-7 days after the grouting is completed, it is checked whether the predetermined anchoring strength is reached. After the predetermined strength is reached, prestressing is performed and fixed by a fastening nut (2).

Claims

1. A double-tube expansion and extrusion type pressure-yielding anchor, characterized by: The invention comprises an anchoring section, a free section and a pressure-releasing member, wherein the pressure-releasing member comprises an expansion tube (5), an extrusion tube (9), a hollow cone (7), a force-bearing tube (8) and a connecting member (6); the expansion tube (5) and the extrusion tube (9) are both connected to the connecting member (6) through end threads, the inner wall diameter of the expansion tube (5) is larger than the outer wall diameter of the extrusion tube (9), a gap exists between the two tubes and the two tubes are on the same axis; the outer wall diameter of the force-bearing tube (8) is smaller than the inner wall diameter of the section to be expanded (5-2), and the inner wall diameter of the force-bearing tube (8) is larger than the outer wall diameter of the section to be extruded (9-2); the outer wall diameter of the hollow cylinder (7-3) at the end of the hollow cone (7) is equal to the inner wall diameter of the expansion section (5-1) and larger than the inner wall diameter of the section to be expanded (5-2); the hollow diameter (7-4) at the end of the hollow cone (7) is equal to the outer wall diameter of the extrusion section (9-1) and smaller than the outer wall diameter of the section to be extruded (9-2) The hollow cone (7) and the stress-bearing tube (8) are combined into a whole through threaded connection. The hollow cone (7) is placed in the gap between the expansion section (5-1) and the extrusion section (9-1). The stress-bearing tube (8) is placed in the gap between the section to be expanded (5-2) and the section to be extruded (9-2). One end of the stress-bearing tube (8) passes through the gap formed by the outer tail end clamp (5-3) and the inner tail end clamp (9-3), and is connected to the free section rod body (11) through the end thread. The end of the free section rod body (11) is an anchor head (13) with an enlarged diameter. The outer diameter of the anchor head has a circle of grouting holes (12). The anchor rod body is a hollow structure for pressure grouting. The anchor tail part includes a pad (3), a fastening bolt (2), and a wedge-shaped grouting plate (4). There is a reserved hole in the middle of the pad (3) and the wedge-shaped grouting plate (4) for passing the hollow threaded rod (6-1) at one end of the connecting member (6).

2. A double-tube expansion and extrusion type pressure-yielding anchor as claimed in claim 1, characterized in that: The expansion tube (5) and the extrusion tube (9) have the same length, and the inner wall of the expansion tube (5) and the outer wall of the extrusion tube (9) are provided with tiny threads or protrusions to increase friction.

3. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: The expansion tube (5) is a tubular structure, integrally formed by a mold, and comprises an expansion section (5-1), a section to be expanded (5-2), and an outer tail end clamp (5-3). The inner wall of the end of the expansion section (5-1) is provided with a thread, which is connected to the connecting member (6). The diameter of the tube wall of the expansion section (5-1) is larger than the diameter of the tube wall of the section to be expanded (5-2). The wall thickness of the expansion tube (5) gradually increases inward from the outer tail end clamp (5-3) until the minimum inner wall radius is the same as the outer wall radius of the load-bearing tube (8), and this wall thickness is maintained to extend 20 mm to 40 mm in the axial direction.

4. A double-tube expansion and extrusion type pressure-yielding anchor as claimed in claim 1, characterized in that: The extruded tube (9) is a tubular structure, integrally formed by a mold, and comprises an extrusion section (9-1), a section to be extruded (9-2), and an inner tail end clamp (9-3). The outer wall of the end of the extruded section (9-1) is provided with a thread, which is connected to the connecting member (6). The diameter of the tube wall of the extruded section (9-1) is smaller than the diameter of the tube wall of the section to be extruded (9-2). The wall thickness of the extruded tube (9) gradually increases from the inner tail end clamp (9-3) outward until the maximum outer wall radius is the same as the inner wall radius of the stressed tube (8), and this wall thickness is maintained to extend 20 mm to 40 mm in the axial direction.

5. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: One end of the connecting member (6) is a hollow threaded rod (6-1) connected to the fastening bolt (2), and the other end is a quasi-hollow cylinder. The outer ring wall of the quasi-hollow cylinder has a thread (6-2) adapted to and connected to the end thread of the expansion tube (5), and the inner ring wall of the quasi-hollow cylinder has a thread (6-3) adapted to and connected to the end thread of the extrusion tube (9).

6. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: The hollow cone (7) is molded in an integrated manner, with a middle portion being a hollow truncated cone (7-2), the hollow portion of the hollow truncated cone (7-2) being an inverted truncated cone, one end of the hollow cone (7) being a connecting thread (7-1) connected to the force-bearing tube (8), and the other end being a hollow cylinder (7-3), the interior of the hollow cylinder (7-3) being a hollow diameter (7-4); the outer wall diameter of the hollow cylinder (7-3) being 1-3 mm larger than the inner wall diameter of the section to be expanded (5-2), and the hollow diameter inside the hollow cylinder (7-3) being 1-3 mm smaller than the outer wall diameter of the tube to be extruded (9-2).

7. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: The diameter of the slurry discharge hole (12) is 20-30 mm, and the number of slurry discharge holes around the enlarged diameter anchor head (13) is 5-8.

8. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: The anchor rod bodies are all hollow tubes, and grouting can be performed from the grouting port (1), and the grout flows out from the grouting hole (12).

9. The double-tube expansion and extrusion type pressure-yielding anchor rod according to claim 1, characterized in that: The hollow cone (7) and the stress-bearing tube (8) are connected by end threads, and can also be welded or integrally formed in a factory.

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