Combined prestressed anchor rod and anchoring construction method thereof

Abstract

The application provides a combined prestressed anchor rod and an anchoring construction method thereof, and belongs to the technical field of engineering construction. The combined prestressed anchor rod comprises an anchor rod body, a sleeve, a pre-tightening assembly and a combined anchor head. The anchor rod body has a first threaded end and a second threaded end arranged opposite to each other. The sleeve is arranged on the anchor rod body. The pre-tightening assembly is arranged on the first threaded end and is used for being threadedly connected with the first threaded end during anchoring, so that the anchor rod body is pre-tightened, and the position of the second threaded end is changed. The combined anchor head is threadedly connected with the second threaded end. The wedge body has an opening end. The combined anchor head can be inserted into the wedge body through the opening end under the pre-tightening action, so that the wedge body is expanded, and anchoring is realized. The application has multiple anchoring mechanisms, so that the anchoring stability and reliability can be improved.

Description

Technical Field

[0001] This invention relates to the field of engineering construction technology, and in particular to a combined prestressed anchor rod and its anchoring construction method. Background Technology

[0002] Anchor bolt support is one of the most important support methods for solving underground engineering problems, and it is widely used in tunnel, hydropower station, and mine construction worldwide.

[0003] However, existing anchor bolt technologies are insufficient to meet diverse construction needs. Current anchor bolt support systems primarily employ resin anchor bolts, slotted pipe anchor bolts, and expansion shell prestressed anchor bolts. These methods suffer from certain structural problems, high material costs, complex construction processes, and stringent construction requirements. Furthermore, their anchoring mechanisms are relatively simplistic, resulting in poor anchoring reliability. Additionally, prestress loss can occur during the prestressing application stage, affecting the overall structural stability. If effective measures are not taken, this can easily lead to substandard project quality, creating safety hazards and seriously endangering personnel safety and subsequent project use.

[0004] Therefore, there is an urgent need for an anchor bolt with multiple anchoring mechanisms to solve existing construction technical problems. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one deficiency of the prior art and provide a combined prestressed anchor rod with multiple anchoring mechanisms.

[0006] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

[0007] According to one aspect of the present invention, a combined prestressed anchor bolt is provided, comprising: The anchor bolt body has a first threaded end and a second threaded end that are arranged opposite to each other; A sleeve is fitted onto the anchor bolt body; A pre-tightening component is disposed on the first threaded end and is used to engage with the first threaded end during anchoring to pre-tighten the anchor body and change the position of the second threaded end; The combined anchor head is threadedly connected to the second threaded end; The expansion wedge has an open end, and the combined anchor head can extend into the expansion wedge through the open end under pre-tightening action to expand the expansion wedge and achieve anchoring.

[0008] In some exemplary embodiments of the present invention, based on the foregoing solution, the sleeve has a first connecting end; The first connecting end is the end closest to the second threaded end, and the first connecting end is connected to the connecting end of the expansion wedge.

[0009] In some exemplary embodiments of the present invention, based on the foregoing scheme, the first connecting end and the connecting end of the expansion wedge are connected by a ring pressing method.

[0010] In some exemplary embodiments of the present invention, based on the foregoing solution, the sleeve further has a second connecting end, which is the end close to the first threaded end; The combined prestressed anchor bolt also includes a sleeve retaining ring, which is sleeved on the second connecting end.

[0011] In some exemplary embodiments of the present invention, based on the foregoing scheme, the combined prestressed anchor bolt further includes a limiting ring, which is disposed in the middle position inside the sleeve to limit the installation position and movement position of the anchor bolt body.

[0012] In some exemplary embodiments of the present invention, based on the foregoing scheme, the preload assembly includes: a torque nut, wherein the internal thread of the torque nut engages with the external thread of the first threaded end.

[0013] In some exemplary embodiments of the present invention, based on the foregoing scheme, the pre-tightening component further includes: a tray, which is sleeved on the anchor rod body and disposed away from the first threaded end; and a washer, which is sleeved on the anchor rod body and located between the tray and the torque nut.

[0014] In some exemplary embodiments of the present invention, based on the foregoing scheme, the gasket is a spherical gasket.

[0015] According to another aspect of the present invention, a method for anchoring a combined prestressed anchor is provided, the method comprising: S1: Drill anchor bolt holes on the working surface; S2: Push the combined prestressed anchor rod into the anchor rod hole to achieve full-length anchorage; S3: Rotate the torque nut. When the combined anchor head is embedded in the expansion wedge and the expansion wedge is fully squeezed out, continue to rotate the torque nut until the first threaded end stops moving, thus completing the anchoring.

[0016] In some exemplary embodiments of the present invention, based on the foregoing scheme, the diameter of the anchor bolt hole is smaller than the diameter of the sleeve before closure.

[0017] As can be seen from the above technical solution, the present invention has the following advantages and positive effects: On the one hand, the pre-tightening component, through its threaded engagement with the first threaded end, effectively pre-tightens the anchor bolt body. This ensures the anchor bolt is under tension before use, providing a stable foundation for subsequent anchoring work and enhancing its reliability and stability during operation. On the other hand, the pre-tightening operation allows for changes in the position of the combined anchor head, enabling flexible adjustment of the anchor bolt's shape and position to adapt to various complex installation conditions under different working scenarios and anchoring requirements. When the combined anchor head extends into the expansion wedge body under pre-tightening and expands the expansion wedge body, anchoring can be achieved quickly and firmly. This anchoring method is relatively simple to operate, and the method of expanding the expansion wedge body ensures a uniform distribution of anchoring force, thereby effectively improving the anchoring effect and stability.

[0018] Furthermore, the sleeve and the anchor hole can form a single full-length anchorage, while the expansion wedge and the combined anchor head can achieve a double end anchorage. Thus, the combined prestressed anchor provided by this invention has multiple anchorage mechanisms, thereby enhancing anchorage stability and reliability. Attached Figure Description

[0019] The above and other features and advantages of the present invention will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0020] Figure 1 This is a structural schematic diagram of one embodiment of the combined prestressed anchor rod of the present invention; Figure 2 This is a schematic diagram of another embodiment of the combined prestressed anchor rod of the present invention; Figure 3 This is a flowchart of the anchoring construction method of the present invention; Figure 4 This is a schematic diagram illustrating the working principle of the sleeve; Figure 5 This is a schematic diagram illustrating the working principle of the expansion wedge. Figure 6 This is a schematic diagram illustrating the principle of the anchoring construction method of the present invention.

[0021] Explanation of reference numerals in the attached figures 1. Anchor bolt body; 2. Torque nut; 3. Washer; 4. Tray; 5. Sleeve retainer; 6. Sleeve; 7. Limiting ring; 8. Expansion wedge; 9. Combined anchor head. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0023] The features, structures, or characteristics described above can be combined in any suitable manner in one or more embodiments, and the features discussed in the various embodiments are interchangeable where possible. In the above description, numerous specific details are provided to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details described, or other methods, components, materials, etc., can be employed. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring various aspects of the invention.

[0024] Although relative terms such as "up" and "down" are used in this invention to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the icon's arrangement is flipped so that it is upside down, the component described as "up" will become the component described as "down". Other relative terms such as "high", "low", "top", "bottom", "front", "back", "left", and "right" also have similar meanings. When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0025] In this invention, the terms “a,” “an,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “comprising,” “including,” and “having” are used to indicate an open-ended inclusion meaning and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.

[0026] According to one aspect of the present invention, a combined prestressed anchor bolt is provided, with reference to Figure 1 and Figure 2 As shown, the combined prestressed anchor bolt includes: An anchor body 1 has a first threaded end and a second threaded end arranged opposite to each other; Sleeve 6 is fitted onto the anchor bolt body 1; A pre-tightening component is disposed on the first threaded end and is used to engage with the first threaded end during anchoring to pre-tighten the anchor rod body 1, change the position of the second threaded end (the rod body moves upward relative to the end nut, driving the second threaded end enlarger to squeeze the expansion wedge 8, expanding inside the anchor rod cavity, and achieving end anchoring).

[0027] The combined anchor head 9 is threadedly connected to the second threaded end; The expansion wedge 8 has an open end, and the combined anchor head 9 can extend into the interior of the expansion wedge 8 through the open end under pre-tightening action to expand the expansion wedge 8 and squeeze the rock wall to achieve end anchoring.

[0028] On the one hand, the pre-tightening component, through its threaded engagement with the first threaded end, effectively pre-tightens the anchor bolt body 1. This ensures the anchor bolt is under tension before use, providing a stable foundation for subsequent anchoring work and enhancing its reliability and stability during operation. On the other hand, the pre-tightening operation can change the position of the combined anchor head 9, allowing for flexible adjustment of the anchor bolt's shape and position under different working scenarios and anchoring requirements to adapt to various complex installation conditions. When the combined anchor head 9 extends into the expansion wedge body 8 under pre-tightening and expands the expansion wedge body 8, anchoring can be achieved quickly and firmly. This anchoring method is relatively simple to operate, and the method of expanding the expansion wedge body 8 ensures a uniform distribution of anchoring force, thereby effectively improving the anchoring effect and stability.

[0029] Furthermore, the sleeve 6 and the anchor hole can form a single full-length anchorage, while the expansion wedge 8 and the combined anchor head 9 can achieve a double end anchorage. Thus, the combined prestressed anchor provided by the present invention has multiple anchorage mechanisms, thereby enhancing anchorage stability and reliability.

[0030] This invention does not impose specific limitations on the structure of the pre-tightening component. For example, in some embodiments, a sleeve 6 with internal threads can be used, the internal thread of which is adapted to the external thread of the first threaded end. By rotating the sleeve 6, it moves along the first threaded end, thereby achieving the pre-tightening operation of the anchor bolt body 1. Alternatively, a structure composed of multiple adjustable wedges can be used, with these wedges installed around the first threaded end. The magnitude of the prestress on the anchor bolt body 1 can be changed by adjusting the position of the wedges. A combined structure with a helical spring and an adjusting nut can also be used. The helical spring is sleeved outside the first threaded end, and the adjusting nut is screwed onto the thread of the first threaded end, compressing the helical spring. By adjusting the screwing in and out of the adjusting nut, the compression degree of the spring is changed, thereby achieving the pre-tightening adjustment of the anchor bolt body 1.

[0031] In the embodiments provided by this invention, the pre-tightening assembly includes a torque nut 2. The internal thread of the torque nut 2 engages with the external thread on the first threaded end. On one hand, the torque nut 2, through its threaded connection with the first threaded end, converts the externally applied rotational force into prestress along the axial direction of the anchor rod, ensuring that the anchor rod body 1 is under a certain tension before anchoring, thereby transmitting the prestress. On the other hand, during anchoring, the threaded connection structure of the torque nut 2 can prevent sudden relaxation or fluctuation of the prestress through the friction and engagement force between the threads when the anchor rod is subjected to external force, maintaining the stability of the anchoring system. This effectively stabilizes the tightening force. Furthermore, the torque nut 2 can be precisely rotated and adjusted according to actual needs, flexibly controlling the magnitude of the prestress to adapt to different anchoring conditions and requirements. Simultaneously, its robust structure and reliable threaded connection ensure good performance during long-term use and prevent failure due to environmental factors or external impacts.

[0032] In addition, to both diffuse prestress and reinforce the surrounding rock while preventing its movement and deformation, the pre-tensioning assembly, in the exemplary embodiment provided by this invention, further includes a tray 4, which is fitted onto the anchor bolt body 1 and positioned away from the first threaded end. On one hand, because the tray 4 has a large contact area, it can evenly distribute the prestress applied by the torque nut 2 onto the surface of the surrounding rock, preventing excessive local stress from damaging the surrounding rock. This allows the prestress to be more effectively transferred to the anchoring area, enhancing the stability and reliability of the anchoring. Therefore, positioning the tray 4 away from the first threaded end serves to transmit and diffuse the prestress. On the other hand, the tray 4, through close contact with the surrounding rock, increases the integrity and strength of the surrounding rock. When subjected to external loads or geological stress, the tray 4 can effectively prevent the displacement and deformation of the surrounding rock, providing a stable support foundation for the anchor bolt, thereby ensuring the long-term effectiveness of the anchoring system. Therefore, the tray 4 can both reinforce the surrounding rock and prevent displacement.

[0033] To ensure sufficient contact between the torque nut 2 and the tray 4, a gasket 3 can be placed between them. In some embodiments, the gasket 3 can be made of a highly elastic rubber material or a polymer material with similar properties. It has a certain thickness and a suitable elastic coefficient, and when placed between the torque nut 2 and the tray 4, it can form a flexible connecting layer between them. When the torque nut 2 is tightened, the elastic buffer gasket 3 can automatically deform elastically according to the surface flatness and pressure distribution between the torque nut 2 and the tray 4, filling any small gaps and uneven areas that may exist between them, thereby ensuring a tight, all-around fit between the torque nut 2 and the tray 4.

[0034] Considering the need for a full fit between the contact surfaces of the torque nut 2 and the tray 4, in the embodiment provided by this invention, the gasket 3 is defined as a spherical gasket 3. The special spherical structure of the spherical gasket 3 allows it to adaptively adjust the relative positional relationship between the torque nut 2 and the tray 4 within a certain angular range. Even during installation or when minor angular deviations occur between components due to external forces, its own deformation ensures a tight connection between the two, effectively reducing stress concentration and energy loss caused by loose connections. Therefore, the spherical gasket 3 can be used to ensure a full fit between the contact surfaces of the torque nut 2 and the tray 4, improving the connection quality.

[0035] In practical applications, after the anchor rod is installed in the hole, it may be subjected to external forces from the hole wall, resulting in a closed situation. In order to avoid the anchor rod being squeezed and closed by the hole wall, thus affecting its normal working performance and service life, and to enhance the full-length anchorage for a more reliable fixing effect, a sleeve 6 with a certain strength and suitable structure can be tightly fitted on the outside of the anchor rod body 1. The sleeve 6 can cooperate well with the anchor rod body 1 and the surrounding anchoring environment to jointly build a stable anchoring system.

[0036] Based on this, the sleeve 6 has a first connecting end, which is the end near the second threaded end, and is connected to the connecting end of the expansion wedge 8 through the first connecting end.

[0037] The sleeve 6 not only provides protection for the anchor bolt body 1, reducing erosion and wear from external environmental factors such as soil, sand, and moisture during installation and use, thus extending the anchor bolt's service life, but also, through its connection with the expansion wedge 8 and its positional relationship on the anchor bolt body 1, effectively transmits and distributes the force generated during anchoring between the anchor bolt body 1 and the expansion wedge 8. When the anchor bolt is subjected to external forces, the sleeve 6 can evenly transmit the force to the entire anchoring system, preventing structural damage caused by excessive local stress.

[0038] In addition, the presence of sleeve 6 not only provides a clear installation benchmark and guide for the installation of anchor bolts, but also limits the range of movement of expansion wedge 8, ensuring that expansion wedge 8 can be expanded and kept in a stable state according to design requirements during the anchoring process, thereby enhancing the anchoring effect and stability of the entire anchor bolt.

[0039] This invention does not impose specific limitations on the connection method between the first connecting end and the expansion wedge 8. For example, in some embodiments, it can be achieved through mechanical connection such as threaded connection, pin connection, or welding. In the example embodiment provided by this invention, to ensure the reliability and sealing of the connection, the first connecting end and the expansion wedge 8 are connected by a ring compression method.

[0040] Compared to ordinary connection methods, the ring-press connection can withstand greater tensile and shear forces, making the connection between the first connecting end and the expansion wedge 8 more robust and less prone to loosening during anchor operation, thus ensuring the structural integrity of the entire anchor system under stress. It also creates a good seal at the connection point, preventing external dust, moisture, and impurities from entering, effectively avoiding corrosion and damage. Furthermore, it helps maintain stable anchor connection performance in special environments (such as underwater or damp underground environments). In addition, due to the uniform pressure distribution of the ring-press connection, the force transmitted from the sleeve 6 to the expansion wedge 8 or back from the expansion wedge 8 is more evenly distributed on the connection interface, reducing stress concentration, improving force transmission efficiency, and thus better maximizing the anchoring effect of the entire anchor system.

[0041] During the installation and use of the anchor bolt, the sleeve 6 may tend to slide axially along the anchor bolt body 1 due to various external forces and vibrations. To limit the axial movement and deformation of the sleeve 6 on the anchor bolt body 1, some limiting structures can be provided on the sleeve 6 or the anchor bolt body 1 to limit the sleeve 6. For example, in some embodiments, a protrusion can be provided at the end of the sleeve 6 or an annular groove can be machined on the anchor bolt body 1 at the position corresponding to the sleeve 6. However, considering structural stability, in the exemplary embodiment provided by the present invention, the sleeve 6 also has a second connecting end, which is the end close to the first threaded end; the combined prestressed anchor bolt also includes a sleeve retaining ring 5, which is sleeved on the second connecting end.

[0042] Thus, the presence of the sleeve retaining ring 5 provides restraint at the end of the sleeve 6, ensuring that the sleeve 6 always remains in the designed position, thereby guaranteeing the stability of the entire anchoring system. Furthermore, the clamping action of the sleeve retaining ring 5 on the sleeve 6 makes the connection between the sleeve 6 and the anchor rod body 1 more secure, increasing the tightness of the connection near the second connection end. This effectively reduces the possibility of relative rotation or loosening between the two, facilitating effective force transmission and the achievement of the anchoring effect.

[0043] Based on this, considering that radial movement of the anchor bolt body 1 within the sleeve 6 may also affect the anchoring effect and system stability, in some embodiments, an annular rubber liner can be provided on the inner wall of the sleeve 6, or some small pits or textures can be machined on the inner wall of the sleeve 6 to increase the frictional resistance between the inner wall of the sleeve 6 and the anchor bolt body 1, thereby preventing radial sliding of the anchor bolt body 1 within the sleeve 6. However, considering the stability and service life of the anchor bolt structure, in the example embodiment provided by this invention, a limiting ring 7 is provided on the inner wall of the sleeve 6. This limiting ring 7 is located in the middle position inside the sleeve 6, which not only restricts the installation position of the anchor bolt body 1 (i.e., restricts the anchor bolt body 1 to the central position), but also restricts its radial movement.

[0044] The limiting ring 7 is usually made of a material with a certain strength and rigidity. Its structure is relatively stable and it is not easy to deform significantly due to long-term use or external impact. Therefore, it can meet the requirements of structural stability and service life.

[0045] According to another aspect of the invention, reference Figure 3 As shown, a method for anchoring a combined prestressed anchor rod is also provided, the method including: S1: Drill anchor bolt holes on the working surface; S2: Push the combined prestressed anchor rod into the anchor rod hole to achieve full-length anchorage; S3: Rotate the torque nut 2. When the combined anchor head 9 is embedded in the expansion wedge body 8 and the expansion wedge body 8 is fully squeezed open, continue to rotate the torque nut 2 until the first threaded end stops moving, thus completing the anchoring.

[0046] In S1, anchor bolt holes are drilled on the working surface.

[0047] This invention does not limit the method of drilling anchor bolt holes. For example, in some embodiments, an anchor bolt drill can be used for drilling, as can a down-the-hole drill or a handheld pneumatic rock drill. Those skilled in the art can selectively use the above-mentioned drilling tools according to the actual situation.

[0048] When drilling the anchor bolt hole, it is important to ensure that the diameter of the anchor bolt hole is smaller than the diameter of the sleeve 6 before it is closed. This ensures that the sleeve 6 can pass smoothly through the anchor bolt hole before installation. If the diameter of the anchor bolt hole is larger than the diameter of the sleeve 6 before it is closed, the sleeve 6 will not be able to close during insertion, exerting radial pressure on the hole wall and leading to full-length anchoring failure. Clearly, when the diameter of the anchor bolt hole is smaller than the diameter of the sleeve 6 before it is closed, the sleeve 6 can fit tightly against the anchor bolt hole wall after insertion, as subsequent installation operations proceed. This increases the friction and engagement force between the sleeve 6 and the anchor bolt hole wall, improving the stability of the entire anchoring system. During anchoring, it better transmits and distributes the anchoring force, preventing uneven force distribution due to excessive gaps between the sleeve 6 and the anchor bolt hole wall, which would negatively impact the anchoring effect.

[0049] In S2, the combined prestressed anchor rod is pushed into the anchor bolt hole to achieve full-length anchoring.

[0050] Figure 4 The diagram illustrates the working principle of the sleeve, demonstrating the mechanism of full-length mechanical anchoring of the combined prestressed anchor rod: the combined anchor rod is inserted into the pre-drilled anchor hole. Since the diameter of the anchor hole is slightly smaller than the diameter of the sleeve 6, the outer wall of the sleeve 6 is squeezed by the hole wall, causing the sleeve 6 to close radially. At the same time, the hole wall is subjected to a radial force that hinders the closure of the sleeve 6 itself, thereby generating a frictional anchoring force along the hole wall direction, thus achieving full-length anchoring.

[0051] When pushing the combined prestressed anchor rod provided by this invention into the anchor hole, it is important to note that the worker should hold the first threaded end and align the second threaded end with the expansion wedge 8 with the entrance of the anchor hole, keeping the axis of the anchor rod basically coincident with the axis of the anchor hole. Then, the combined prestressed anchor rod should be pushed into the anchor hole steadily with force. During the pushing process, the progress of the combined prestressed anchor rod should be observed at all times to ensure that it is not obstructed or stuck.

[0052] After the combined prestressed anchor is fully pushed into the anchor hole, check whether the position of the combined prestressed anchor in the hole meets the requirements, and check whether the tray 4 is tightly attached to the surface of the surrounding rock. If there is a gap between the tray 4 and the surrounding rock, the position of the tray 4 needs to be adjusted appropriately or the shim 3 or other methods are used to fill it, so as to ensure that the tray 4 can effectively transfer and diffuse the prestress.

[0053] In S3, rotate the torque nut 2. When the combined anchor head 9 is embedded in the expansion wedge body 8 and the expansion wedge body 8 is fully squeezed open, continue to rotate the torque nut 2 until the first threaded end stops moving, thus completing the anchoring.

[0054] As the torque nut 2 rotates, the anchor rod drives the combined anchor head 9 and the expansion wedge 8 to produce relative displacement, squeezing the expansion wedge 8 to achieve end expansion effect, squeezing against the anchor rod hole wall, and achieving initial end anchoring.

[0055] Based on this, continue to rotate the torque nut 2. Due to the special design of the anchor head end, when the end of the expansion wedge 8 is pressed against the anti-overslip buckle at the anchor head end, it is stopped and the anchor rod end no longer displaces. Continue to rotate the torque nut 2, which is equivalent to fixing one end and continuing to stretch the other end. This process realizes the application of prestress.

[0056] The expansion of the wedge 8 is primarily radial, applying pressure to the surrounding rock. As the wedge 8 expands, the contact area between it and the rock wall, as well as the surrounding rock, gradually increases, leading to increased friction and compressive forces. These forces together constitute the anchoring force. When the wedge 8 is fully expanded, the anchoring force reaches a level sufficient to firmly fix the anchor in the surrounding rock. At this point, a stable anchoring system is formed between the anchor, the wedge 8, and the surrounding rock. In this system, the anchor transmits prestress to the surrounding rock through the wedge 8, while the surrounding rock supports the anchor through its reaction force on the wedge 8, thus achieving anchoring.

[0057] Figure 5 The diagram illustrates the working principle of the expansion wedge 8, demonstrating the mechanism of mechanical anchoring at the end of the combined prestressed anchor bolt: the combined anchor head 9 is embedded in the lower open end of the expansion wedge 8 and is tightly connected to the second threaded end via threads. During the application of prestress, the anchor bolt body 1 moves upward, which drives the combined anchor head 9 to move upward synchronously, further embedding it into the expansion wedge 8. After the combined anchor head 9 moves upward a certain distance, it stops moving upward due to the anti-overslip buckle at its end, preventing it from being over-embedded in the expansion wedge 8. At this time, the expansion wedge 8 is fully open, applying end anchoring force to the surrounding hole wall.

[0058] refer to Figure 6 As shown, the more specific steps are: First, anchor bolt holes are drilled on the working surface. The entire anchor bolt is pushed into the anchor bolt hole, and the sleeve 6 is squeezed and closed, generating radial force on the hole wall, forming frictional anchoring force, achieving full-length anchoring, and completing the first step of mechanical anchoring. Then, the torque nut 2 is rotated to apply prestress to the anchor bolt, while the combined anchor head 9 moves upward and continues to embed into the expansion wedge 8. After moving upward to a certain position, it is stuck. At this time, the expansion wedge 8 has been fully squeezed open, and the end of the anchor bolt expands, achieving end anchoring, and finally completing the second step of mechanical anchoring and the prestressing application process.

[0059] Therefore, in the first step of mechanical anchoring, the sleeve 6, after being compressed and closed, generates a radial force on the borehole wall, making the connection between the anchor rod and the borehole wall tighter. On the one hand, this tight connection increases the friction between the two, and the resulting frictional anchoring force can effectively resist various external forces, such as tension and shear forces, that the anchor rod experiences during operation, greatly improving the stability of the anchoring. On the other hand, by forming frictional anchoring force through the compression of the sleeve 6, reliable anchoring effects can be achieved for anchor bolt borehole walls under different geological conditions (whether hard rock or soft rock strata) by adjusting the degree of compression of the sleeve 6 and the magnitude of the radial force, thus expanding the application range of this anchoring technology in various complex geological environments. Moreover, achieving full-length anchoring means that the anchor rod forms an effective connection and anchoring effect with the surrounding medium (such as the borehole wall) along its entire length. Compared with traditional local anchoring methods, it can better distribute and bear loads from different directions, reducing the risk of anchoring failure due to excessive local stress.

[0060] During the second step of mechanical anchoring, rotating the torque nut 2 applies prestress to the anchor rod, placing it in a pre-tensioned state. This prestress can preemptively offset some of the potential tensile force during anchor operation, thereby improving the anchor rod's load-bearing capacity. Simultaneously, the combined anchor head 9 continues to embed into the expansion wedge 8 and fully pushes it apart, achieving end anchoring and further increasing the anchoring force at the anchor rod end, making the overall anchoring effect of the anchor rod more reliable.

[0061] The combination of end anchoring and full-length anchoring forms a dual anchoring mechanism, achieving strong fixation from the whole to the parts, greatly improving the pull-out resistance and stability of the anchor rod.

[0062] Prestressing allows anchor bolts to be in a taut state before operation, effectively reducing deformation and displacement of the surrounding rock or structure under external forces. This is particularly useful in projects with stringent deformation requirements, such as tunnels and underground engineering, where it effectively controls the convergence and deformation of the surrounding rock, ensuring the stability and safety of the engineering structure.

[0063] The dual anchoring mechanism and prestressing reduce loosening and fatigue damage of anchor bolts during long-term use, extending their service life. Simultaneously, effective anchoring reduces maintenance and replacement work due to anchor bolt failure, lowering project maintenance costs.

[0064] It should be understood that the application of this invention is not limited to the detailed structure and arrangement of the components proposed herein. This invention can have other embodiments and can be implemented and performed in various ways. The foregoing variations and modifications fall within the scope of this invention. It should be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more individual features mentioned or apparent in the text and / or drawings. All these different combinations constitute multiple alternative aspects of the invention. The embodiments described herein illustrate the best known mode for carrying out the invention and will enable those skilled in the art to utilize the invention.

Claims

1. A composite prestressed anchor bolt, characterized in that, include: The anchor bolt body has a first threaded end and a second threaded end that are arranged opposite to each other; A sleeve is fitted onto the anchor bolt body. The sleeve has a first connecting end and a second connecting end. The first connecting end is the end closer to the second threaded end. The first connecting end is connected to the connecting end of the expansion wedge. The second connecting end is the end closer to the first threaded end. A pre-tightening assembly is disposed on the first threaded end. The pre-tightening assembly includes a torque nut. The internal thread of the torque nut is used to engage with the external thread of the first threaded end during anchoring to pre-tighten the anchor body and change the position of the second threaded end. The combined anchor head is threadedly connected to the second threaded end; An expansion wedge has an open end, and the combined anchor head can extend into the expansion wedge through the open end under pre-tightening action to expand the expansion wedge and achieve anchoring; the end of the combined anchor head is provided with an anti-overslip buckle, which abuts against the end of the expansion wedge when the combined anchor head moves relative to the expansion wedge to a preset position to restrict the combined anchor head from continuing to extend into the expansion wedge; a sleeve retaining ring is fitted onto the second connecting end; A limiting ring is provided at the middle position inside the sleeve to limit the installation position and movement position of the anchor bolt body.

2. The combined prestressed anchor bolt according to claim 1, characterized in that, The first connecting end is connected to the connecting end of the expansion wedge by a ring pressing method.

3. The combined prestressed anchor bolt according to claim 1, characterized in that, The pretensioning assembly also includes: The tray is fitted onto the anchor bolt body and positioned away from the first threaded end. A gasket is fitted onto the anchor body and located between the tray and the torque nut.

4. The combined prestressed anchor bolt according to claim 3, characterized in that, The gasket is a spherical gasket.

5. An anchoring construction method based on the combined prestressed anchor rod according to any one of claims 1-4, characterized in that, The anchoring construction method includes: S1: Drill anchor bolt holes on the working surface; S2: Push the combined prestressed anchor rod into the anchor rod hole to achieve full-length anchorage; S3: Rotate the torque nut. When the combined anchor head is embedded in the expansion wedge and the expansion wedge is fully squeezed out, continue to rotate the torque nut until the first threaded end stops moving, thus completing the end anchoring.

6. The anchoring construction method according to claim 5, characterized in that, The diameter of the anchor hole is smaller than the diameter of the sleeve before it is closed.

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