A gradually-diameter reinforced cage expanding head anchor rod

Abstract

The present application relates to geotechnical engineering supporting structure technical field, especially to a kind of gradually changing diameter reinforcement cage enlarged head anchor rod, comprising: anchor rod, anchor rod sleeve, vertical reinforcement, variable diameter stirrup, support frame and temperature control device;Anchor rod is equipped with anchor rod sleeve, anchor rod sleeve head end is installed with vertical reinforcement, variable diameter stirrup is along vertical reinforcement axial interval arrangement and is connected with vertical reinforcement, and is formed into reinforcement cage jointly;Support frame two ends are respectively connected with anchor rod, vertical reinforcement;Anchor rod, anchor rod sleeve, vertical reinforcement, variable diameter stirrup, support frame jointly constitute radial expansion type reinforcement cage anchor head;Temperature control device is electrically connected with variable diameter stirrup by temperature control wire.This application is driven support frame by external force and pushes vertical reinforcement, makes vertical reinforcement occur bending deformation, and changes diameter with temperature control device control variable diameter stirrup, makes the reinforcement cage after expansion form preset function curve form;This application improves the deformation mode of anchor rod expansion, effectively improves the deformation control precision.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering support structure technology, and in particular to a gradually increasing diameter steel cage enlarged head anchor rod. Background Technology

[0002] Variable diameter reinforced cage anchors, as a novel anchoring technology in underground engineering support, are widely used in various engineering projects with stringent anchoring performance requirements, such as basement anti-buoyancy and slope support, and are particularly suitable for anchoring construction scenarios under complex geological conditions. Extensive engineering practice has verified that, compared to traditional ordinary anchors, variable diameter reinforced cage anchors exhibit significant advantages in overall structural stability and ultimate pull-out bearing capacity after molding, resulting in superior comprehensive anchoring performance.

[0003] Currently, most existing variable-diameter rebar cage anchors rely on releasing the spring stirrups to expand the rebar cage outward from a contracted state, thus achieving diameter variation. However, this type of spring-driven expansion method is greatly affected by external factors such as geology, space, and environment at the construction site, resulting in poor driving force stability and an inability to precisely control the expansion range and forming state of the rebar cage. When working inside complex and confined boreholes, insufficient precision in rebar cage expansion control is highly likely, leading to defects such as insufficient expansion, excessive deviation in the enlarged head's forming dimensions, and poor forming regularity. These defects cause uneven stress on the anchoring structure, and under long-term load and external dynamic disturbances, the anchoring structure is prone to continuous plastic deformation, significantly reducing the anchor's pull-out bearing capacity and structural stability, ultimately leading to anchoring failure and seriously affecting the overall support safety and service life of underground engineering projects. Therefore, precisely controlling the diameter expansion deformation process of the anchor and ensuring the forming quality of the enlarged head are the core research directions for optimizing and upgrading variable-diameter rebar cage anchor technology. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the prior art and provide a gradually increasing diameter steel cage enlarged head anchor rod, which aims to achieve higher pull-out bearing capacity, more precise deformation control and more reliable overall structure, so as to solve the problem that the steel cage enlargement process is difficult to control precisely in the existing variable diameter steel cage anchor rod, which easily leads to anchorage failure.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A radially enlarged diameter rebar cage anchor bolt, characterized in that it comprises: an anchor bolt, an anchor bolt sleeve, vertical bars, multiple variable diameter stirrups, multiple support frames, and a temperature control device; the anchor bolt is fitted with the anchor bolt sleeve, and the vertical bars are arranged in a circumferential array at the head end of the anchor bolt sleeve; the multiple variable diameter stirrups are spaced apart along the axial direction of the vertical bars and connected to the vertical bars to form a rebar cage; the support frames are disposed between the anchor bolt and the vertical bars, and both ends of the support frames are respectively connected to the anchor bolt and the vertical bars; the anchor bolt, the anchor bolt sleeve, the vertical bars, the multiple variable diameter stirrups, and the multiple support frames together constitute a radially enlarged diameter rebar cage anchor head; the anchor head adopts a radially enlarged diameter structure, which can significantly increase the contact area with soil and concrete, improve the interfacial gripping force, and effectively enhance the overall pull-out anchoring performance; the temperature control device is electrically connected to the variable diameter stirrups through a temperature control wire; The vertical ribs are provided with multiple fixed nodes at intervals along their own axial direction. The vertical ribs are fixedly connected to the variable diameter stirrups through the fixed nodes. The fixed nodes provide precise installation points for the support frame and the variable diameter stirrups, unify the assembly positions of each component, and improve the assembly accuracy and overall stability of the structure. The variable diameter stirrup includes a stirrup sleeve and a shape memory alloy ring spring installed inside the stirrup sleeve; the temperature control device is electrically connected to the shape memory alloy ring spring through a temperature control wire; the shape memory alloy ring spring has the deformation characteristics of contraction upon heating and expansion upon cooling; the maximum diameter change of each shape memory alloy ring spring is designed to match the limit position after the corresponding vertical bar fixed node is expanded; when the steel cage is not expanded, it is cylindrical; when the temperature control device is energized, the shape memory alloy ring spring is heated to a temperature higher than the shape change temperature, maintaining a contracted state (austenitic phase); when the steel cage is expanded, the temperature control device is de-energized, the shape memory alloy ring spring cools and expands, and the structural shape is deformed from a ring spring shape to a ring cylinder shape; the variable diameter stirrup has multiple joints on its inner side, one end of which is fixedly connected to the stirrup sleeve, and the other end is hinged to the support frame at the fixed node of the vertical bar through bolts.

[0006] Furthermore, a groove is formed on the outer surface of the end of the anchor head, and a sliding groove extending along the length of the groove is formed on the inner wall of the groove. The support frame is slidably connected to the sliding groove. The sliding groove provides sliding guidance for the support frame, allowing the support frame to slide flexibly in the sliding groove along the anchor axial direction as the reinforcing cage expands in diameter, adapting to the expansion stroke, ensuring a smooth expansion process, and at the same time limiting the movement trajectory of the support frame to prevent jamming.

[0007] Furthermore, the anchor rod has a hollow structure, and a grouting hole is provided at the head end of the anchor rod. The grouting hole is connected to the hollow inner cavity of the anchor rod. The hollow inner cavity of the anchor rod and the grouting hole form a grouting channel. During construction, grout can be injected around the anchor head. The grout fills the gaps and combines with the anchor head, improving the integrity of the anchor body and the anchoring strength.

[0008] Furthermore, the anchor rod is provided with a first stop for axially limiting and stopping the anchor rod sleeve and a second stop for axially limiting and stopping the variable diameter stirrup along the axis; the first stop is located near the head end of the anchor rod sleeve, and the second stop is located near the support frame; the first stop prevents the anchor rod sleeve from moving towards the support frame, and the second stop limits the maximum stroke of the support frame sliding along the groove; Furthermore, the anchor sleeve has a threaded hole at its head end, and one end of the vertical bar has an external threaded section. The vertical bar is threadedly connected to the anchor sleeve through the external threaded section. The use of a threaded connection to assemble the vertical bar and the anchor sleeve ensures a firm connection, convenient assembly and disassembly, and guarantees the circumferential distribution accuracy of the vertical bar, ensuring uniform stress distribution throughout the reinforcing cage.

[0009] Furthermore, the tail end of the anchor rod is provided with an external thread section, and a rotating nut is rotatably connected to the tail end of the anchor rod through the external thread section. The rotating nut is close to the tail end of the anchor rod sleeve. By applying an external torque force to the rotating nut, the rotating nut is rotated and drives the anchor rod to move axially. As the anchor rod moves axially, the support frame connected to the anchor rod pushes the vertical reinforcement bar, causing the vertical reinforcement bar to bend and deform outward, thereby completing the expansion operation of the steel cage.

[0010] Compared with the prior art, the beneficial effects of the present invention are: This invention uses an external force to drive a support frame to push the vertical reinforcement nodes, causing the vertical reinforcement to bend and deform. A temperature control device regulates the diameter of the variable-diameter stirrups, resulting in a pre-defined functional curve shape for the expanded reinforcement cage. Compared to traditional anchor bolts, this product offers superior structural stability and significantly improved ultimate tensile strength. This invention optimizes and innovates the expanded-head anchor bolt for reinforcement cages, applying a functional curve shape to the reinforcement cage structure and improving the anchor bolt's diameter expansion deformation method. This effectively enhances deformation control precision, strengthens overall structural stability, increases tensile strength, and improves anchoring performance. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the three-dimensional structure of the present invention after diameter expansion; Figure 2 This is a three-dimensional structural diagram of the present invention before diameter expansion; Figure 3 This is a cross-sectional view of the anchor rod of the present invention; Figure 4 This is a cross-sectional view of the minimum diameter of the variable diameter stirrup of the present invention; Figure 5 This is a cross-sectional view of the variable diameter stirrup of the present invention at its maximum diameter; Figure 6 This is a schematic diagram of the vertical rib structure of the present invention; Figure 7 This is a cross-sectional view of the anchor sleeve of the present invention.

[0012] Figure 8 This is a schematic diagram illustrating the application of the present invention.

[0013] In the diagram: 1. Anchor bolt; 11. First stop; 12. Second stop; 13. Groove; 14. Slide groove; 15. Grouting hole; 2. Anchor bolt sleeve; 21. Threaded hole; 3. Vertical reinforcement; 31. Fixed node; 311. First fixed node; 312. Second fixed node; 313. Third fixed node; 314. Fourth fixed node; 4. Variable diameter stirrup; 41. Joint; 42. Shape memory alloy ring spring; 43. Stirrup sleeve; 411. First variable diameter stirrup; 412. Second variable diameter stirrup; 413. Third variable diameter stirrup; 414. Fourth variable diameter stirrup; 5. Support frame; 51. First support frame; 52. Second support frame; 53. Third support frame; 54. Fourth support frame; 6. Rotating nut; 7. Temperature control device; 71. Temperature control wire. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] exist Figures 1 to 8 In the structure shown, the present invention provides a gradually increasing diameter steel cage enlarged head anchor bolt, comprising: A gradually increasing diameter steel cage enlarged head anchor bolt includes: an anchor bolt 1, an anchor bolt sleeve 2, vertical bars 3, four variable diameter stirrups 4 (in order: first variable diameter stirrup 411, first variable diameter stirrup 412, first variable diameter stirrup 413 and first variable diameter stirrup 414), four support frames 5 (in order: first support frame 51, second support frame 52, third support frame 53 and fourth support frame 54), and a temperature control device 7; The anchor rod 1 has a hollow structure, and a grouting hole 15 is provided at the head end of the anchor rod 1. The grouting hole 15 is connected to the hollow inner cavity of the anchor rod 1. The hollow inner cavity of the anchor rod 1 and the grouting hole 15 form a grouting channel. During construction, grout can be injected around the anchor head 1. The grout fills the gaps and combines with the anchor head, improving the integrity and anchoring strength of the anchor body. A groove 13 is provided on the outer surface of the head end of the anchor rod 1. A sliding groove 14 extending along the length of the groove 13 is provided on the inner wall of the groove 13. The support frame 5 is slidably connected to the sliding groove 14. The sliding groove 14 provides sliding guidance for the support frame, allowing the support frame 5 to slide flexibly within the sliding groove 14 along the axial direction of the anchor rod 1 as the diameter of the reinforcing cage expands, adapting to the diameter expansion stroke and ensuring the diameter expansion is complete. The movement is smooth and the movement trajectory of the support frame 5 is restricted to prevent jamming. The tail end of the anchor rod 1 is provided with an external thread section, and the tail end of the anchor rod 1 is rotatably connected to a rotating nut 6 through the external thread section. The rotating nut 6 is close to the tail end of the anchor rod sleeve 2. The anchor rod 1 is provided with a first stop 11 for axially limiting and stopping the anchor rod sleeve 2 and a second stop 12 for axially limiting and stopping the variable diameter stirrup along the axis. The first stop 11 is located close to the head end of the anchor rod sleeve 2, and the second stop 12 is located close to the support frame 5. The first stop 11 prevents the anchor rod sleeve from moving to one side of the support frame 5, and the second stop 12 limits the maximum stroke of the support frame 5 sliding along the slide groove 14. The anchor bolt 1 is fitted with an anchor bolt sleeve 2. Vertical reinforcing bars 3 are arranged in a circumferential array at the head end of the anchor bolt sleeve 2. The vertical reinforcing bars are installed at the head end of the anchor bolt sleeve 2 as follows: a threaded hole 21 is provided at the head end of the anchor bolt sleeve 2, and one end of the vertical reinforcing bar 3 has an external thread section. The vertical reinforcing bar 3 is threadedly connected to the anchor bolt sleeve 2 through the external thread section. This threaded connection method ensures a secure connection between the vertical reinforcing bar 3 and the anchor bolt sleeve 2, facilitates easy assembly and disassembly, and guarantees the circumferential distribution accuracy of the vertical reinforcing bars 3, ensuring uniform stress distribution throughout the reinforcing cage. The vertical reinforcing bar 3 has four fixed nodes 31 spaced along its axial direction (sequentially the first fixed node 311, the second fixed node 312, the third fixed node 313, and the fourth fixed node 314). The vertical reinforcing bar 3 is fixedly connected to the variable diameter stirrups 4 through the fixed nodes 31. The fixed nodes 31 provide precise installation points for the support frame 5 and the variable diameter stirrups 4, unifying the assembly positions of various components and improving the structural assembly accuracy and overall stability. Four variable-diameter stirrups 4 are arranged at intervals along the axial direction of the vertical bar 3 and connected to the vertical bar 3 to form a steel cage. Each variable-diameter stirrup 4 includes a stirrup sleeve 43 and a shape memory alloy ring spring 42 installed in the stirrup sleeve 43. The maximum expansion diameters of the four variable-diameter stirrups are different from each other, and the maximum diameter deformation of each shape memory alloy ring spring 42 is customized according to the limit size after expansion of the four corresponding fixed nodes 31 on the vertical bar 3. The temperature control device 7 is electrically connected to the shape memory alloy ring spring 42 via a temperature control wire 71. The shape memory alloy ring spring 42 has the deformation characteristics of contraction upon heating and expansion upon cooling. The maximum diameter change of each shape memory alloy ring spring 42 is designed to match the limit position of the corresponding vertical rib 3 fixed node 31 after diameter expansion. When the steel cage is not expanded, it is cylindrical. When the temperature control device 7 is energized, the shape memory alloy ring spring 42 is heated to a temperature higher than the shape change temperature, maintaining a contracted state (austenitic phase). During the steel cage diameter expansion operation, the temperature control device 7 is de-energized, and the shape memory alloy ring spring 42 cools and expands, changing its structural shape from a ring spring. The stirrup is deformed into a ring-shaped cylinder; multiple joints 41 are provided on the inner side of the variable diameter stirrup 4, one end of the joint 41 is fixedly connected to the stirrup sleeve 43, and the other end is hinged to the support frame 5 by bolts at the fixed node 31 of the vertical bar 3; the support frame 5 is arranged between the anchor rod 1 and the vertical bar 3, and both ends of the support frame 5 are respectively connected to the anchor rod 1 and the vertical bar 3; the first fixed node 311 and the first support frame 51 are hinged, the second fixed node 312 and the second support frame 52 are hinged, the third fixed node 313 and the third support frame 53 are hinged, and the fourth fixed node 314 and the fourth support frame 54 are hinged; Before expansion, the steel cage is cylindrical, and the variable diameter stirrups 4 are contracted to the minimum diameter. During expansion, the four support frames 5 push the vertical bars 3 at the fixed nodes 31 to make the vertical bars bend and expand outward. The temperature control device 7 drives the shape memory alloy ring spring 42 to expand the diameter, which drives the variable diameter stirrups 4 to expand synchronously. Finally, the vertical bars 3 bend to form a trumpet-shaped steel cage that conforms to the function curve, and the variable diameter stirrups 4 open to the maximum diameter. The steel cage with this function curve configuration has stronger pull-out bearing capacity, higher structural reliability, and better anchorage performance.

[0016] Specifically, the shape of the function curve after the vertical reinforcement is enlarged can be understood as solving the minimum revolution surface of the failure body using the variational method and classical Euler equations. The failure body is regarded as a rotating wedge with the centerline of the anchor plug as its axis. The angles between the generatrix of the wedge and the slope surface and the bottom plane of the anchor plug are specific angles, and the failure surface is the minimum revolution surface. The equation of the generatrix of the revolution surface is determined. This shape curve is a key geometric parameter for calculating the ultimate pull-out bearing capacity. Through mathematical derivation, it represents the optimal geometric shape for anchor failure. Experiments have confirmed that it has a higher upper limit of pull-out bearing capacity and strong structural reliability.

[0017] Specifically, the four fixed nodes 31 set on the vertical rib 3 can be understood as the positions x1, x2, x3, and x4 of the four feature points on the x-axis of the function curve, and the vertical height from the first support frame to the fourth support frame can be understood as the heights y1, y2, y3, and y4 of the four feature points on the y-axis of the function curve. By setting the four feature points and their heights on the coordinate axis of the function curve in equal proportions to the heights from the first fixed node to the fourth fixed node of the vertical rib and from the first support frame to the fourth support frame, the shape of the vertical rib conforming to the function curve after it is fully expanded can be more precisely controlled.

[0018] The anchor rod 1, the anchor sleeve 2, the vertical bar 3, the multiple variable diameter stirrups 4, and the multiple support frames 5 together constitute a radially expanded diameter steel cage anchor head; the anchor head adopts a radially expanded diameter structure, which can significantly increase the contact area with the soil and concrete, improve the interface gripping force, and effectively enhance the overall pull-out anchoring performance.

[0019] Working principle and usage process of this invention: During the assembly stage, firstly, take multiple vertical ribs 3 and tighten the threaded end of each rib into the threaded hole 21 on the end face of the anchor sleeve 2. Then, insert the anchor rod 1 into the internal cavity of the anchor sleeve 2 from the rear end. Four fixing nodes 31 on the vertical ribs 3 are connected to four support frames 5 (the first fixing node 311 connects to the first support frame 51, the second fixing node 312 connects to the second support frame 52, the third fixing node 313 connects to the third support frame 53, and the fourth fixing node 314 connects to the fourth support frame 54). The ends of the four support frames 5 furthest from the vertical ribs 3 are slidably connected to the grooves 14 in the anchor groove 13. Then, turn on the power to the temperature control device 7. Heat is transferred to the shape memory alloy ring spring 42, causing it to contract due to heat, thus driving... Four variable-diameter stirrups are brought together to their minimum diameter state; using locking bolts, the four variable-diameter stirrups 4, with diameters increasing from small to large, are locked and fixed. The joints 41 of the four variable-diameter stirrups are correspondingly fastened to the four fixed nodes 31 of the vertical reinforcement 3 (the first variable-diameter stirrup 411 is fixedly connected to the first fixed node 311, the second variable-diameter stirrup 412 is fixedly connected to the second fixed node 312, the third variable-diameter stirrup 413 is fixedly connected to the third fixed node 313, and the fourth variable-diameter stirrup 414 is fixedly connected to the fourth fixed node 314); this completes the overall pre-installation of the anchor bolt (e.g., Figure 2 (as shown) Then, the pre-assembled anchor rod 1 is inserted into the pre-drilled anchor hole. At the same time, the power supply to the temperature control device 7 is cut off, and the heating of the shape memory alloy ring spring 42 is stopped. When the shape memory alloy ring spring 42 cools down to the martensitic softening state as the ambient temperature decreases, the rotating nut 6 is screwed into the top of the tail of the anchor rod 1. The rotating nut 6 is screwed in at a uniform speed, driving the anchor rod 1 to move along its own axis toward the grouting hole 15. When the anchor rod 1 moves axially, the slide 14 simultaneously pulls the four support frames 5 to generate a radial outward pushing force, pushing the fixed node 31 on the vertical bar 3 outward, forcing the vertical bar 3 to bend and expand outward. The shape memory alloy ring spring 42 in the softened state undergoes circumferential extension and expansion under the outward mechanical pushing action of the support frame 5, simultaneously increasing the circumferential diameter of the various stages of variable diameter stirrups 4. The rotating nut 6 is continuously screwed in until the first stop 11 on the anchor rod 1 abuts against the front end face of the anchor rod sleeve 2, the axial travel of the anchor rod reaches the limit, and the gradually increasing diameter steel cage is expanded in place. Finally, cement mortar is injected through the reserved grouting hole 15. After the cement mortar solidifies, the steel cage, anchor rod, mortar and surrounding soil and rock form an integrated anchoring expansion body, and the overall anchoring is completed.

[0020] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gradually increasing diameter steel cage enlarged head anchor bolt, characterized in that, include: Anchor rod (1), anchor rod sleeve (2), vertical bar (3), multiple variable diameter stirrups (4), multiple support frames (5), and temperature control device (7); the anchor rod (1) is fitted with the anchor rod sleeve (2), the vertical bar (3) is installed in a circumferential array at the head end of the anchor rod sleeve (2), multiple variable diameter stirrups (4) are spaced apart along the axial direction of the vertical bar (3) and connected to the vertical bar (3) to form a steel cage; the support frame (5) is set between the anchor rod (1) and the vertical bar (3), and both ends of the support frame (5) are connected to the anchor rod (1) and the vertical bar (3) respectively; the anchor rod (1), the anchor rod sleeve (2), the vertical bar (3), multiple variable diameter stirrups (4), and multiple support frames (5) together constitute a radially expanded diameter steel cage anchor head; the temperature control device is electrically connected to the variable diameter stirrups through a temperature control wire; The vertical bar (3) is provided with multiple fixed nodes (31) at intervals along its own axis, and the vertical bar (3) is fixedly connected to the variable diameter stirrup (4) through the fixed nodes (31); The variable diameter stirrup (4) includes a stirrup sleeve (43) and a shape memory alloy ring spring (42) installed inside the stirrup sleeve (43); the temperature control device (7) is electrically connected to the shape memory alloy ring spring (42) through a temperature control wire (71); the variable diameter stirrup (4) is provided with multiple joints (41) on its inner side, one end of the joint (41) is fixedly connected to the stirrup sleeve (43), and the other end is hinged to the support frame (5) by bolts at the fixed node (31) of the vertical bar (3).

2. The gradually changing diameter steel cage enlarged head anchor bolt according to claim 1, characterized in that, The anchor rod (1) has a groove (13) on the outer surface of its head end. The inner wall of the groove (13) has a sliding groove (14) extending along the length of the groove (13). The support frame (5) is slidably connected to the sliding groove (14).

3. The gradually changing diameter steel cage enlarged head anchor bolt according to claim 1, characterized in that, The anchor rod (1) has a hollow structure, and a grouting hole (15) is provided at the head end of the anchor rod (1). The grouting hole (15) is connected to the hollow inner cavity of the anchor rod (1).

4. The gradually increasing diameter steel cage enlarged head anchor bolt according to claim 1, characterized in that, The anchor rod (1) is provided with a first stop (11) for axially limiting and stopping the anchor rod sleeve (2) and a second stop (12) for axially limiting and stopping the variable diameter stirrup along the axis; the first stop (11) is provided near the head end of the anchor rod sleeve (2) and the second stop (12) is provided near the support frame (5).

5. The gradually changing diameter steel cage enlarged head anchor bolt according to claim 1, characterized in that, The anchor sleeve (2) has a threaded hole (21) at its head end, and one end of the vertical bar (3) has an external thread section. The vertical bar (3) is threadedly connected to the anchor sleeve (2) through the external thread section.

6. The gradually changing diameter steel cage enlarged head anchor bolt according to claim 1, characterized in that, The anchor rod (1) has an external thread section at its tail end, and a rotating nut (6) is rotatably connected to the tail end of the anchor rod (1) through the external thread section. The rotating nut (6) is close to the tail end of the anchor rod sleeve (2).

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