Tension and compression combined type high pre-stressed anchor cable structure, hole bottom reaming structure and construction method

Abstract

The invention provides a tension and compression combined type high pre-stressed anchor cable structure, a hole bottom reaming structure and a construction method.The tension and compression combined type high pre-stressed anchor cable structure comprises an anchor cable, and a bearing plate is arranged at the end of the anchor cable; the bearing plate is a memory metal plate; a limiting plate is arranged at the end part of the anchor cable; the bearing plate is wound outside the anchor cable in a spring shape; one end of the bearing plate is fixedly connected with the limiting plate; guide grooves are formed in the outer edge of the top of the bearing plate and the inner edge of the bottom of the bearing plate; the bearing plate is in a conical spiral line shape after being heated; a locking plate and a locking device are arranged outside the anchor cable; the diameter of the locking plate is larger than that of the anchor hole, the locking plate is located at the anchor hole opening, and the locking device is fixed to the anchor cable and abuts against the locking plate. According to the invention, the bottom hole of the anchor hole can be conveniently chambered, the operation is convenient, the chambering difficulty is reduced, and the chambering quality is ensured; and positioning is carried out during reaming, so that the reaming structure is prevented from inclining, the reaming quality is guaranteed, reaming inclining is avoided, and then follow-up installation of an anchor cable structure is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of anchor cable construction, and in particular to a tension-compression combined high prestressed anchor cable structure and a bottom hole expansion structure and a construction method. Background Art

[0002] Anchor cables are divided into tension type and pressure type according to the stress mode of the anchor body. The ultimate bearing capacity of the anchor section is generally controlled by the lateral friction resistance of the rock and soil: when the anchor length is less than the critical value, the anchor force increases with the increase of the anchor length; when the tension type anchor body is pulled, after reaching the critical value of tension, cracks will appear between the upper end anchor body and the rock and soil, and damage will occur; when the pressure plate of the conventional pressure type anchor cable is pulled, the lower end anchor body will be compressed, and after reaching the critical value of tension, cracks will appear between the upper end anchor body and the rock and soil, and damage will occur. If the dispersed type (multi-group anchor section) anchor cable is not used, when the rock and soil of the anchor hole wall and the anchor material are certain, the ultimate anchoring force of the anchor cable will be Certain, tension type, pressure type , tension and compression combination type is .

[0003] From the mechanism analysis, the expanded bottom anchor can break the limit of the ultimate anchoring force of the pressure anchor: when the strength of the anchor material meets the requirements, the ultimate anchoring force , is the bearing capacity of the rock and soil foundation on the bearing plate, A is the plate area. The development of bottom anchor cables and construction technology can bring huge economic benefits to the engineering industry, and the research is of great significance.

[0004] Regarding bottom hole expansion: Currently, large-diameter pile foundation bottom expansion is widely used in the field of building construction, and the technology has been overcome, but there is less research on anchor holes. The anchor holes are long and have small diameters, and the anchoring sections are mostly bedrock, making bottom expansion difficult. Summary of the Invention

[0005] The main purpose of the present invention is to provide a tension-compression combined high prestressed anchor cable structure and a bottom hole expansion structure and construction method, so as to solve the problems of difficulty in bottom expansion and insufficient anchoring force of the bottom expansion anchor cable in the prior art.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A tension-compression combined high prestressed anchor cable structure comprises an anchor cable with a pressure-bearing plate provided at the end of the anchor cable; The pressure plate is a memory metal plate; A limiting plate is provided at the end of the anchor cable.

[0007] In a preferred embodiment, the pressure plate is spring-shaped and wound around the outside of the anchor cable; One end of the pressure plate is fixedly connected to the limiting plate; The outer edge of the top of the pressure plate and the inner edge of the bottom of the pressure plate are both provided with guide grooves; The pressure plate takes on a conical spiral shape after being heated; A locking plate and a locking device are provided outside the anchor cable; The diameter of the locking plate is larger than the diameter of the anchor hole and is located at the anchor hole. The locking device is fixed to the anchor cable and presses against the locking plate.

[0008] The tension-compression combined high prestressed anchor cable bottom hole expansion structure includes a base, one side of the base is provided with a connector connected to the drill pipe, and the other end of the base is provided with a support rod and two fixing plates; Two reaming rods are hinged between the two fixing plates; the two reaming rods are located on both sides of the support rod; A connecting frame is provided between the reaming rod and the support rod, and the connecting frame is used to control the rotation of the reaming rod.

[0009] In a preferred embodiment, the reaming rod includes a rotating rod; The rotating rod is hinged to the fixed plate through a fixed shaft; A plurality of crushing blocks are arranged on one side of the rotating rod away from the supporting rod.

[0010] In a preferred embodiment, the connecting frame includes a plurality of connecting rods; One end of the connecting rod is hinged to the support rod through a first rotating shaft, and the other end of the connecting rod is hinged to the reaming rod through a second rotating shaft; The second rotating shaft is rotatably connected to the connecting rod; A slide groove is provided in the reaming rod, and the second rotating shaft passes through the slide groove and slides along the slide groove; A pull rod is provided inside the reaming rod, one end of the pull rod is fixedly connected to the reaming rod, and the other end of the pull rod is fixedly connected to the second rotating shaft; The pull rod is a memory metal rod.

[0011] In a preferred embodiment, a connecting sleeve is provided at the bottom of the support rod; both the connecting sleeve and the support rod are provided with connecting holes; A rotating plate is provided at the bottom of the connecting sleeve, and a cushion block is sleeved on the outside of the rotating plate; The rotating plate is a circular plate, and the pad is rotatably connected to the rotating plate; A plane bearing is provided between the pad and the rotating plate.

[0012] In a preferred solution, the rotating plate is provided with a rotating sleeve, and a transmission rod is provided at the bottom of the connecting sleeve, and the transmission rod is plugged into the interior of the rotating sleeve; A movable groove is provided in the rotating sleeve, and a slider is provided on the side of the transmission rod, and the slider is slidably connected to the inside of the movable groove; The end of the transmission rod is provided with a spring; The bottom of the pad is provided with a thorn block.

[0013] The construction method of the tension-compression combined high prestressed anchor cable includes the following steps: S1. Drill anchor holes in the anchor cable construction area; S2, anchor hole bottom expansion; S3, lowering the anchor cable with the pressure plate, which is located at the bottom of the hole; The pressure plate is a memory metal pressure plate; S4. The pressure plate is heated, and deformed by the heat. The anchor cable applies tension to change the pressure plate into a circular plate shape, and the plate is pressed against the hole wall after the hole is expanded. Casting molding; S5. The anchor hole is locked and the anchor cable construction is completed.

[0014] In a preferred solution, S4 includes: S41, pouring high heat release C40 fine stone concrete into the pressure plate through the orifice through the pouring pipe, until the pressure plate reaches a transition temperature, causing the pressure plate to change from a spring shape to a conical spiral shape; The first pouring is completed; S42, the anchor cable is tightened by applying tension, and the pressure plate changes from a conical spiral to a circular plate shape, and is left to stand for a period of time; S43. When the strength of the first pouring concrete reaches 70%-80%, apply the first tensioning force ; S44, pour C30 or C40 fine stone concrete, wait for the second pouring concrete strength to reach 75%; the second pouring is completed; S45, apply the second tension, total tension .

[0015] In a preferred solution, S2 includes: S21, the anchor cable hole-forming structure enters the bottom of the anchor hole, and the drill rod drives the anchor cable hole-forming structure to rotate; S22, the drill rod drives the anchor cable hole-forming structure to rotate, and friction between the anchor cable hole-forming structure and the hole bottom structure generates heat; S23, the memory metal rod in the anchor cable hole-forming structure is deformed by heat, driving the hole-expanding structure to open and start rotating to expand the hole; S24. During the hole expansion process, the temperature gradually increases, the memory metal rod gradually deforms due to the increased heat, and the hole expansion structure gradually opens; S25, the hole expansion structure is opened to the limit position, and the hole expansion is completed; S26. Add water to the hole to cool it down, reset the memory metal and hole expansion structure, and remove the anchor cable to form the hole structure.

[0016] The present invention provides a tension-compression combined high prestressed anchor cable structure and a bottom hole expansion structure and a construction method. By adopting the above scheme, the following beneficial effects are achieved: 1. It is convenient to expand the bottom hole of the anchor hole, which is not only convenient to operate, but also reduces the difficulty of expanding the hole and ensures the quality of the expansion.

[0017] 2. Positioning is performed during hole enlargement to avoid skewness of the hole enlargement structure, thereby ensuring the quality of the hole enlargement, avoiding skewness of the hole enlargement, and thus avoiding the installation of the subsequent anchor cable structure.

[0018] 3. The operation is simpler when connecting the anchor cables, and after the construction is completed, the force-bearing area is wider, the stability is better, and the anchoring force is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings and examples: Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the main structure of the present invention; Figure 3 It is a side cross-sectional structural schematic diagram of the present invention; Figure 4 It is a schematic structural diagram of an embodiment of the present invention; Figure 5 It is a schematic structural diagram of an embodiment of the present invention; Figure 6 It is a schematic diagram of the pressure plate structure of the present invention; Figure 7 It is a structural schematic diagram after the anchor cable structure of the present invention is constructed.

[0020] In the picture: Base 1, connector 101, fixed plate 2, fixed shaft 201, support rod 3, reaming rod 4, rotating rod 401, breaking block 402, connecting frame 5, connecting rod 501, first rotating shaft 502, second rotating shaft 503, slide groove 504, pull rod 505, connecting sleeve 601, connecting hole 602, pad 603, rotating plate 604, plane bearing 605, thorn block 606, rotating sleeve 701, transmission rod 702, movable groove 703, slider 704, spring 705, anchor cable 8, locking plate 801, locking device 802, pressure plate 9, limit plate 901, guide groove 902. DETAILED DESCRIPTION

[0021] Example 1: like Figure 6 and 7 As shown, the tension-compression combined high prestressed anchor cable structure includes an anchor cable 8, and a pressure plate 9 is provided at the end of the anchor cable 8; the pressure plate 9 is a memory metal plate. Under normal conditions, Figure 5 As shown, the pressure plate 9 is spring-shaped and wound around the outside of the anchor cable 8. After being heated, the pressure plate 9 gradually changes into a conical spiral shape; a limiting plate 901 is provided at the end of the anchor cable 8, and one end of the pressure plate 9 is fixedly connected to the limiting plate 901.

[0022] The memory metal material used for the pressure plate 9 is preferably nickel-titanium alloy.

[0023] When it is necessary to connect the anchor cable, the pressure plate 9 end of the anchor cable 8 is extended into the expanded hole at the bottom of the anchor hole, and then the pressure plate 9 is heated to change it from a spring shape to a conical spiral shape, and then the anchor cable 8 is pulled, and the pressure plate 9 is pressed against the inner wall of the expanded hole at the bottom of the anchor hole, and then the pulling is continued to make the limit plate 901 become a plate body, and finally the casting can complete the tension-compression combined high prestressed anchor cable connection of this application, which has better connection stability and better anchoring force.

[0024] Furthermore, the outer edge of the top of the pressure plate 9 and the inner edge of the bottom of the pressure plate 9 are both provided with guide grooves 902; when the pressure plate 9 is pulled to become a plate body, the guide grooves 902 are used for connection to ensure stability.

[0025] In a further embodiment, the anchor cable 8 is provided with a locking plate 801 and a locking device 802. The locking device 802 is preferably a nut adapted to the anchor cable 8 or a clamping locking block, which is selected according to the actual situation. The locking plate 801 has a diameter larger than the diameter of the anchor hole and is located at the anchor hole opening. The locking device 802 is fixed to the anchor cable 8 and abuts the locking plate 801. When the anchor cable 8 is connected to the hook, the locking device 802 is tightened to keep the locking plate 801 close to the slope where the anchor hole opening is located, thereby preventing the anchor cable 8 from moving inward and ensuring stability after construction.

[0026] Example 2: like Figure 1 、 2 As shown in Figure 3, a tension-compression combined high prestressed anchor bottom hole expansion structure includes a base 1, a connecting head 101 connected to the drill rod is provided on one side of the base 1, and the connecting head 101 is preferably an existing connecting structure connected to the existing drill rod, and the other end of the base 1 is provided with a support rod 3 and two fixed plates 2; two reaming rods 4 are hinged between the two fixed plates 2; the two reaming rods 4 are located on both sides of the support rod 3; when reaming, the two reaming rods 4 rotate outward synchronously, and when not reaming, the reaming rods 4 are retracted inward; further, the reaming rod 4 includes a rotating rod 401; the rotating rod 401 is hinged to the fixed plate 2 through a fixed shaft 201; a plurality of crushing blocks 402 are provided on the side of the rotating rod 401 away from the support rod 3, and the crushing block 402 is a crushing block structure commonly used in existing drill bits. When reaming, the rock formation is crushed and the hole is expanded by the crushing block 402.

[0027] In a further embodiment, a connecting frame 5 is provided between the reaming rod 4 and the support rod 3, and the connecting frame 5 is used to control the rotation of the reaming rod 4. Specifically, the connecting frame 5 includes a plurality of connecting rods 501; one end of the connecting rod 501 is hinged to the support rod 3 via a first rotating shaft 502, and the other end of the connecting rod 501 is hinged to the reaming rod 4 via a second rotating shaft 503; the second rotating shaft 503 is rotatably connected to the connecting rod 501; A slot 504 is provided within the reaming rod 4, through which the second rotating shaft 503 passes and slides. The sliding of the second rotating shaft 503 within the slot 504 causes one end of the connecting rod 501 to slide, thereby causing the reaming rod 4 to rotate about the fixed axis 201, thereby expanding and contracting the reaming rod 4. A pull rod 505 is provided within the reaming rod 4. The pull rod 505 is a memory metal rod. One end of the pull rod 505 is fixedly connected to the reaming rod 4, and the other end is fixedly connected to the second rotating shaft 503.

[0028] When the reaming rod 4 needs to be opened, the pull rod 505 is heated and contracted, thereby pulling the second rotating shaft 503 to slide along the sliding groove 504, thereby cooperating with the connecting rod 501 to push the reaming rod 4 to open, and vice versa.

[0029] In a further embodiment: like Figure 4 As shown, a connecting sleeve 601 is provided at the bottom of the support rod 3; both the connecting sleeve 601 and the support rod 3 are provided with a connecting hole 602; a rotating plate 604 is provided at the bottom of the connecting sleeve 601, and a pad 603 is sleeved on the outside of the rotating plate 604; the pad 603 is against the bottom of the anchor hole; the rotating plate 604 is a circular plate, and the pad 603 is rotatably connected to the rotating plate 604; a plane bearing 605 is provided between the pad 603 and the rotating plate 604, and the plane bearing ensures the stability of the relative rotation of the rotating plate 604 and the pad 603.

[0030] During use, after placing the bottom hole reaming structure into the anchor hole, adjust the position so that the pad 603 is located at the center of the bottom of the anchor hole, and then the drill rod of the drilling rig drives the bottom hole reaming structure to perform the reaming operation. At this time, the pad 603 is used for positioning to avoid the bottom hole reaming structure from being skewed, thereby ensuring the quality of the reaming.

[0031] In order to facilitate the spacer 603 to be located at the center of the bottom of the anchor hole, the diameter of the spacer 603 can be set to be the same as the diameter of the anchor hole to facilitate positioning.

[0032] In a further embodiment, Figure 5As shown, the rotating plate 604 is provided with a rotating sleeve 701, and a transmission rod 702 is provided at the bottom of the connecting sleeve 601. The transmission rod 702 is inserted into the interior of the rotating sleeve 701; a movable groove 703 is provided in the rotating sleeve 701, and a slider 704 is provided on the side of the transmission rod 702, which is slidably connected to the interior of the movable groove 703; a spring 705 is provided at the end of the transmission rod 702. When reaming, one end of the hole can be reamed first, and then the drill rig pushes the drill rod to move, thereby driving the bottom hole reaming structure downward. During this process, the transmission rod 702 slides along the rotating sleeve 701 and compresses the spring 705 to maintain the stability of the movement, thereby facilitating the stable increase of the reaming section length to meet different reaming requirements. The bottom of the spacer 603 is provided with a spike block 606, so that when connected, the spike block 606 penetrates into the bottom of the hole to locate the position of the spacer 603.

[0033] Example 3: The construction method of the tension-compression combined high prestressed anchor cable includes the following steps: S1. Drill anchor holes in the anchor cable construction area; S2. Expand the bottom of the anchor hole; specifically: S21, the anchor cable hole-forming structure enters the bottom of the anchor hole, and the drill rod drives the anchor cable hole-forming structure to rotate; S22, the drill rod drives the anchor cable hole-forming structure to rotate, and friction between the anchor cable hole-forming structure and the hole bottom structure generates heat; S23, the memory metal rod in the anchor cable hole-forming structure is deformed by heat, driving the hole-expanding structure to open and start rotating to expand the hole; S24. During the hole expansion process, the temperature gradually increases, the memory metal rod gradually deforms due to the increased heat, and the hole expansion structure gradually opens; S25, the hole expansion structure is opened to the limit position, and the hole expansion is completed; S26. Add water to the hole to cool it down, reset the memory metal and hole expansion structure, and remove the anchor cable to form the hole structure.

[0034] S3, lowering the anchor cable with the pressure plate, which is located at the bottom of the hole; The pressure plate is a memory metal pressure plate; S4. The pressure plate is heated, and deformed by the heat. The anchor cable applies tension to change the pressure plate into a circular plate shape, and the plate is pressed against the hole wall after the hole is expanded. Casting molding; Specifically: S41, pouring high heat release C40 fine stone concrete into the pressure plate through the orifice through the pouring pipe, until the pressure plate reaches a transition temperature, causing the pressure plate to change from a spring shape to a conical spiral shape; The first pouring is completed; S42, the anchor cable is tightened by applying tension, and the pressure plate changes from a conical spiral to a circular plate shape, and is left to stand for a period of time; S43. When the strength of the first pouring concrete reaches 70%-80%, apply the first tensioning force ; S44, pour C30 or C40 fine stone concrete, wait for the second pouring concrete strength to reach 75%; the second pouring is completed S45, apply the second tension, total tension .

[0035] S5. The anchor hole is locked and the anchor cable construction is completed.

[0036] The above method is easy to operate, and not only facilitates the bottom hole expansion operation of the anchor hole, but also ensures the stability of the anchor cable construction, and compared with the existing method, the anchoring force is stronger.

[0037] This application is applicable to the construction of anchor cables, but is not limited to the construction of anchor cables. It is also applicable to the construction of anchor rods, etc. The anchor cables cannot be interpreted as a limitation to this application.

[0038] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. In other words, equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. The tension-compression combined high prestressed anchor cable structure is characterized by: It comprises an anchor cable (8), and a pressure plate (9) is provided at the end of the anchor cable (8); The pressure plate (9) is a memory metal plate; A limiting plate (901) is provided at the end of the anchor cable (8).

2. The tension-compression combined high prestressed anchor cable structure according to claim 1 is characterized by: The pressure plate (9) is spring-shaped and wound around the outside of the anchor cable (8); One end of the pressure plate (9) is fixedly connected to the limiting plate (901); The outer edge of the top of the pressure plate (9) and the inner edge of the bottom of the pressure plate (9) are both provided with guide grooves (902); The pressure plate (9) is in a conical spiral shape after being heated; The anchor cable (8) is provided with a locking plate (801) and a locking device (802) outside; The locking plate (801) has a diameter greater than that of the anchor hole and is located at the anchor hole. The locking device (802) is fixed to the anchor cable (8) and abuts against the locking plate (801).

3. The tension-compression combined high prestressed anchor cable bottom hole expansion structure is characterized by: It comprises a base (1), one side of the base (1) is provided with a connector (101) connected to a drill rod, and the other end of the base (1) is provided with a support rod (3) and two fixing plates (2); Two reaming rods (4) are hinged between the two fixing plates (2); the two reaming rods (4) are located on both sides of the support rod (3); A connecting frame (5) is provided between the reaming rod (4) and the support rod (3), and the connecting frame (5) is used to control the rotation of the reaming rod (4).

4. The tension-compression combined high prestressed anchor cable bottom hole expansion structure according to claim 3 is characterized by: The reaming rod (4) includes a rotating rod (401); The rotating rod (401) is hinged to the fixed plate (2) via the fixed shaft (201); A plurality of crushing blocks (402) are provided on a side of the rotating rod (401) away from the supporting rod (3).

5. The tension-compression combined high prestressed anchor cable bottom hole expansion structure according to claim 3 is characterized by: The connecting frame (5) includes a plurality of connecting rods (501); One end of the connecting rod (501) is hinged to the supporting rod (3) via a first rotating shaft (502), and the other end of the connecting rod (501) is hinged to the reaming rod (4) via a second rotating shaft (503); The second rotating shaft (503) is rotatably connected to the connecting rod (501); A slide groove (504) is provided in the reaming rod (4), and the second rotating shaft (503) passes through the slide groove (504) and slides along the slide groove (504); A pull rod (505) is provided in the reaming rod (4), one end of the pull rod (505) is fixedly connected to the reaming rod (4), and the other end of the pull rod (505) is fixedly connected to the second rotating shaft (503); The pull rod (505) is a memory metal rod.

6. The tension-compression combined high prestressed anchor cable bottom hole expansion structure according to any one of claims 3 to 5, characterized in that: A connecting sleeve (601) is provided at the bottom of the support rod (3); both the connecting sleeve (601) and the support rod (3) are provided with connecting holes (602); A rotating plate (604) is provided at the bottom of the connecting sleeve (601), and a cushion block (603) is sleeved on the outside of the rotating plate (604); The rotating plate (604) is a circular plate, and the pad (603) is rotatably connected to the rotating plate (604); A plane bearing (605) is provided between the pad (603) and the rotating plate (604).

7. The tension-compression combined high prestressed anchor cable bottom hole expansion structure according to claim 6, characterized in that: The rotating plate (604) is provided with a rotating sleeve (701), and a transmission rod (702) is provided at the bottom of the connecting sleeve (601), and the transmission rod (702) is plugged into the interior of the rotating sleeve (701); A movable groove (703) is provided in the rotating sleeve (701), and a slider (704) is provided on the side of the transmission rod (702), and the slider (704) is slidably connected to the inside of the movable groove (703); A spring (705) is provided at the end of the transmission rod (702); A thorn block (606) is provided at the bottom of the cushion block (603).

8. A method for constructing a tension-compression combined high prestressed anchor cable, characterized by: The steps are as follows: S1. Drill anchor holes in the anchor cable construction area; S2, anchor hole bottom expansion; S3, lowering the anchor cable with the pressure plate, which is located at the bottom of the hole; The pressure plate is a memory metal pressure plate; S4. The pressure plate is heated, and deformed by the heat. The anchor cable applies tension to change the pressure plate into a circular plate shape, and the plate is pressed against the hole wall after the hole is expanded. Casting molding; S5. The anchor hole is locked and the anchor cable construction is completed.

9. The method for constructing a tension-compression combined high prestressed anchor cable according to claim 8, characterized in that: Included in S4: S41, pouring high exothermic C40 fine stone concrete into the pressure plate through the orifice through the pouring pipe, and the pressure plate reaches the transition temperature, so that the pressure plate changes from a spring shape to a conical spiral shape; The first pouring is completed; S42, the anchor cable is tightened by applying tension, and the bearing plate changes from a conical spiral shape to a circular plate shape and is left to stand; S43. When the strength of the first pouring concrete reaches 70%-80%, apply the first tensioning force ; S44, pour C30 or C40 fine stone concrete, wait for the second pouring concrete strength to reach 75%; the second pouring is completed; S45, apply the second tension, total tension .

10. The method for constructing a tension-compression combined high prestressed anchor cable according to claim 8, characterized in that: Included in S2: S21, the anchor cable hole-forming structure enters the bottom of the anchor hole, and the drill rod drives the anchor cable hole-forming structure to rotate; S22, the drill rod drives the anchor cable hole-forming structure to rotate, and friction between the anchor cable hole-forming structure and the hole bottom structure generates heat; S23, the memory metal rod in the anchor cable hole forming structure is deformed by heat, driving the hole expansion structure to open and start rotating to expand the hole; S24. During the hole expansion process, the temperature gradually increases, the memory metal rod gradually deforms due to the increased heat, and the hole expansion structure gradually opens; S25, the hole expansion structure is opened to the limit position, and the hole expansion is completed; S26. Add water to the hole to cool it down, reset the memory metal and hole expansion structure, and remove the anchor cable to form the hole structure.

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