A pre-tensioned bottom expansion anchor cable and a construction method for constructing a support structure thereof

Abstract

The invention provides a pre-tensioned expanded bottom anchor cable and a construction method for constructing a support structure thereof. The pre-tensioned expanded bottom anchor cable comprises an expansion drill bit, an extrusion joint, an expanded body anchor head and an anchor bar body. The expansion drill bit is connected to the top of the expanded body anchor head, and the anchor bar body is connected to the tail of the expanded body anchor head through an extrusion joint; the expanded body anchor head comprises a core tube and a support frame, and the support frame comprises two sleeves and a plurality of section rods connected between the two sleeves and distributed along the circumference of the sleeves, and both sleeves are sleeved on the core tube. The expanded bottom anchor cable is drilled into the slope surface according to the designed inclination angle and hole depth; the anchor bar body is tensioned, and the support frame is compressed and stretched to form a "lantern"-shaped expanded body bracket; grouting is injected into the "lantern" to form a dense expanded body to anchor the expanded bottom anchor cable in a stable soil layer; a lattice retaining wall is constructed, and the prestressed expanded body anchor cable and the lattice retaining wall are connected by anchors to form a spatial support structure, so that the unstable soil on the slope surface is anchored in the stable soil layer.

Description

Technical Field

[0001] The invention belongs to the technical field of expanded body anchoring, and in particular relates to a pre-tensioned expanded bottom anchor cable and a construction method for constructing a support structure thereof. Background Art

[0002] Geotechnical engineering anchoring technology is an important branch in the current geotechnical engineering field. It is one of the more economical and effective methods to solve the stability problems of geotechnical engineering. At present, geotechnical anchoring technology has been widely used in energy, transportation, water conservancy and urban infrastructure construction, and the anchoring structure form and process are constantly being updated and improved.

[0003] As a new type of high-bearing capacity support structure, the expanded anchor cable (rod) is increasingly valued by the majority of engineering personnel. Its use breaks through the adverse effects caused by the insufficient length of the traditional anchor cable (rod), and greatly improves the economy and effectiveness of the support structure. According to the different expansion forming methods, the expanded anchor cable (rod) can be roughly divided into the inflatable (grouting) expansion string type, the tension (compression) expansion type, etc. At present, the research on the inflatable (grouting) expansion string type anchor cable (rod) is still in the development stage, and there are many problems in terms of safety, construction technology, cost, etc., while the tension (compression) expansion type anchor cable (rod) is easier to be developed and applied due to the diversity of the structure of the expanded section. Despite this, this type of anchor cable (rod) has not been widely promoted in engineering. The main reasons are as follows: the expansion forming effect is poor, or the expanded strength after forming is low, which cannot meet the design bearing capacity requirements; the expanded structure is too complicated and the manufacturing cost is high; the construction and installation process is immature, affecting the progress of the project. Summary of the invention

[0004] In view of the problems existing in existing expanded body anchor cables (rods), such as complex expanded body section structure, high manufacturing cost, cumbersome installation and construction, difficult expanded body forming, or unable to ensure expanded body strength, the present invention creatively proposes a pre-tensioned expanded bottom anchor cable and a construction method for constructing a support structure thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] A pre-tensioned bottom-enlarged anchor cable comprises an expansion drill bit (2-1), an extrusion joint (2-2), an expanded anchor head (2-3) and an anchor bar body (2-4); the expansion drill bit (2-1) is connected to the top of the expanded anchor head (2-3), and the anchor bar body (2-4) is connected to the tail of the expanded anchor head (2-3) through the extrusion joint (2-2);

[0007] The expanded anchor head (2-3) comprises a core tube (2-6) and a support frame (2-5); a raised flange (2-8) is provided on the outer wall of the core tube (2-6) along the longitudinal direction of the core tube; the reaming drill bit (2-1) is fixedly installed on the top end of the core tube (2-6); and the extrusion joint (2-2) is fixedly connected to the rear end of the core tube (2-6); the support frame (2-5) comprises two sleeve rings (2-10) and a plurality of section rods (2-12) connected between the two sleeve rings and distributed along the circumference of the sleeve rings; the two sleeve rings (2-10) are both sleeved on the core tube (2-6), one sleeve ring is close to one side of the reaming drill bit (2-1), and the other sleeve ring is close to one side of the extrusion joint (2-2); an external thread is provided on the sleeve ring (2-10) of the support frame (2-5) close to the extrusion joint (2-2) for threaded connection with a drill pipe; each sleeve ring (2-10) is provided with a plurality of section rods (2-12) connected between the two sleeve rings and distributed along the circumference of the sleeve rings; the two sleeve rings (2-10) are sleeved on the core tube (2-6), one sleeve ring is close to one side of the reaming drill bit (2-1), and the other sleeve ring is close to one side of the extrusion joint (2-2); an external thread is provided on the sleeve ring (2-10) of the support frame (2-5) close to the extrusion joint (2-2) for threaded connection with a drill pipe; The outer wall of the drill bit (2-10) is provided with a plurality of hinge points (2-11) at intervals along its circumference, and the two ends of a single segment rod are respectively hingedly connected to the hinge points of the two sleeve rings, and a hinge point is provided in the middle part of the single segment rod; a groove matching with the flange (2-8) of the core tube (2-6) is provided on the inner wall of each sleeve ring (2-10); after the sleeve ring (2-10) is sleeved on the core tube (2-6), the sleeve ring (2-10) is installed by matching the groove of the sleeve ring (2-10) with the flange (2-8) of the core tube (2-6), so that the rotational freedom of the sleeve ring (2-10) and the core tube (2-6) can be limited but the axial sliding freedom can not be limited, so that when the drill rod is drilling, the expansion anchor head (2-3) and the core tube (2-6) can be drilled synchronously, and when the two sleeve rings (2-10) slide relatively close to each other on the core tube (2-6), the segment rod between the two sleeve rings can be stretched to form a "lantern"-shaped expansion bracket.

[0008] In the above technical solution, the number of the flanges (2-8) is two, and the two flanges (2-8) are symmetrically arranged with respect to the diameter of the core tube.

[0009] In the above technical solution, each section rod is composed of two sub-section rods of equal length that are hingedly connected.

[0010] In the above technical solution, a limiting ring (2-9) is provided on the core tube (2-6), and the limiting ring (2-9) is located on the inner side of the collar (2-10) close to the side of the reaming drill bit (2-1), and is used to limit the collar, so as to prevent the collar (2-10) close to the side of the reaming drill bit (2-1) of the support frame (2-5) from moving upward during drilling, thereby causing the support frame (2-5) to be stretched and unable to continue drilling.

[0011] In the above technical solution, a limit spring (2-7) is arranged between the two collars (2-10), and the limit spring (2-7) is sleeved on the core tube (2-6). The limit spring (2-7) keeps the support frame (2-5) in an un-expanded state during the drilling process.

[0012] In the above technical solution, after the node rods of the support frame (2-5) are stretched out, they squeeze the surrounding soil to form an expanded cavity. After grouting is injected into the cavity, the node rods act as tendons, greatly ensuring the strength of the expanded section.

[0013] In the above technical solution, the number of hinge points (2-11) on the collar (2-10) can be appropriately increased or decreased according to the design bearing capacity.

[0014] In the above technical solution, a corrugated pipe (3), an anchor plate (4) and a spiral rib (5) are sequentially mounted on the tail of the anchor bar body (2-4) and concrete is poured. The bottom of the corrugated pipe (3) should penetrate 10 cm to 20 cm into the slope surface to prevent the concrete and the anchor bar body (2-4) from being poured as a whole and unable to be tensioned.

[0015] In the above technical solution, the node rod is preferably in the shape of an elongated plate. When the node rods of the support frame are in a closed state, the node rods can completely wrap around the periphery of the core tube, thereby increasing the effective area of ​​the node rods on the surrounding soil as much as possible and increasing the cavity space formed after the support frame is opened as much as possible.

[0016] The construction method of using the pre-tensioned bottom-enlarged anchor cable to construct a support structure comprises the following steps:

[0017] ① sequentially connecting the hole expansion drill bit (2-1), the expanded anchor head (2-3) and the anchor bar body (2-4) into a whole;

[0018] ② Locate the anchor holes according to the designed points and position the drilling rig according to the designed inclination angle;

[0019] ③ Insert the anchor bar body (2-4) of the bottom anchor cable (2) along the bottom of the drill pipe, and thread the collar (2-10) at the rear end of the support frame to the drill pipe;

[0020] ④ Drilling is performed, during which the anchor bar body (2-4) and the drill rod length are gradually increased according to the designed hole depth;

[0021] ⑤ After the anchor cable is installed, the drill rod is reversed to separate it from the bottom anchor cable (2), and the anchor bar body (2-4) is tensioned after the drill rod is withdrawn 10cm-20cm. During the tensioning of the anchor bar body (2-4), the collar (2-10) is subjected to the pressure from the top of the drill rod, so that the support frame (2-5) is stretched to form a "lantern"-shaped enlarged head;

[0022] ⑥ Use the drill rod to inject grout into the "lantern" shaped enlarged head, and withdraw the drill rod after completion;

[0023] ⑦ Construction of lattice retaining wall (1); after the lattice retaining wall foundation trench is leveled, foundation construction is carried out, and then steel bars are tied and anchor brackets are made (6);

[0024] ⑧ Anchor support (6) construction: insert the corrugated pipe (3), anchor pad (4) and spiral reinforcement (5) into the tail of the anchor reinforcement body (2-4) in sequence, install the anchor support (6) steel formwork, and pour concrete;

[0025] ⑨ Apply prestress; after the concrete strength reaches the design strength, prestress the bottom anchor cable (2) according to the design requirements and lock the bottom anchor cable (2) on the anchor support (6) with an anchor (7), and then seal the anchor.

[0026] The advantages and beneficial effects of the present invention are:

[0027] 1. The pre-tensioned bottom expansion anchor cable of the present invention can quickly expand and squeeze the surrounding soil to form an expanded cavity. After grouting into the cavity, the support frame plays the role of bone reinforcement, and after forming, the quality and strength of the expanded section can be effectively guaranteed;

[0028] 2. The bottom-enlarging anchor cable in the present invention is a segmented assembly structure, each component has a simple structure, a mature manufacturing process, is easy to assemble, and has a low cost;

[0029] 3. The present invention is easy to construct and install. After installation, the bottom-enlarged anchor cable and the lattice retaining wall form a spatial integral support structure, which can effectively ensure that the unstable soil on the slope is anchored in the surrounding stable soil layer, greatly improving the stability of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the support structure constructed by using pre-tensioned and expanded bottom anchor cables according to the present invention.

[0031] Figure 2 yes Figure 1 Schematic diagram of the structure of the pre-tensioned bottom expansion anchor cable.

[0032] Figure 3 yes Figure 2 Schematic diagram of the structure of the expanded anchor head.

[0033] Figure 4 yes Figure 3 Schematic diagram of the structure of the support frame.

[0034] Figure 5 yes Figure 3 Schematic diagram of the structure of the core tube.

[0035] in:

[0036] 1 is a lattice retaining wall, 2 is an expanded bottom anchor cable, 3 is a corrugated pipe, 4 is an anchor pad, 5 is a spiral rib, 6 is an anchor support, 7 is an anchor, 2-1 is an expansion drill bit, 2-2 is an extrusion joint, 2-3 is an expanded anchor head, 2-4 is an anchor bar body, 2-5 is a support frame, 2-6 is a core tube, 2-7 is a limit spring, 2-8 is a flange, 2-9 is a limit ring, 2-10 is a sleeve ring, 2-11 is a hinge point, and 2-12 is a section rod.

[0037] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments.

[0039] Embodiment 1

[0040] A supporting structure constructed by using pre-tensioned bottom-enlarged anchor cables comprises a lattice retaining wall 1, a bottom-enlarged anchor cable 2, a corrugated pipe 3, an anchor pad 4, a spiral reinforcement 5, an anchor inclined support 6 and an anchor 7.

[0041] The bottom expansion anchor cable 2 includes a hole expansion drill bit 2-1, an extrusion joint 2-2, an expanded anchor head 2-3 and an anchor bar body 2-4. The hole expansion drill bit 2-1 is connected to the top of the expanded anchor head 2-3, the extrusion joint 2-2 is connected to the tail of the expanded anchor head 2-3, and the anchor bar body 2-4 is connected to the extrusion joint 2-2.

[0042] Specifically, the expanded anchor head 2-3 includes a core tube 2-6 and a support frame 2-5; two raised flanges 2-8 are provided on the outer wall of the core tube 2-6 along the longitudinal direction of the core tube, and the two flanges 2-8 are symmetrically arranged with the diameter of the core tube, the reaming drill bit 2-1 is fixedly installed on the top of the core tube 2-6, and the extrusion joint 2-2 is fixedly connected to the tail end of the core tube 2-6; the support frame 2-5 includes two collars 2-10 and a plurality of node rods 2-12 connected between the two collars and distributed along the circumference of the collars, the two collars 2-10 are both sleeved on the core tube 2-6, one of the collars is close to the side of the reaming drill bit 2-1, and the other collar is close to the side of the extrusion joint 2-2, and the collar 2-10 of the support frame 2-5 close to the side of the extrusion joint 2-2 is provided with an external thread for threaded connection with the drill pipe; on the outside of the collar 2-10 A plurality of hinge points 2-11 are arranged on the wall along its circumference at intervals, and the two ends of a single section rod are respectively hingedly connected to the hinge points of the two collars, and a hinge point is also arranged in the middle part of the single section rod (that is, each section rod is composed of two sub-section rods of equal length hingedly connected and connected); a groove matching the flange 2-8 of the core tube 2-6 is arranged on the inner wall of the collar 2-10, and after the collar 2-10 is sleeved on the core tube 2-6, the collar 2-10 is installed by matching the groove of the collar 2-10 with the flange 2-8 of the core tube 2-6, which can limit the rotational freedom of the collar 2-10 and the core tube 2-6 but not limit the axial sliding freedom, so that when the drill rod is drilling, the expansion anchor head 2-3 and the core tube 2-5 are drilled synchronously, and when the two collars 2-10 slide relatively close to each other on the core tube 2-6, the section rod between the two collars can be stretched to form a "lantern"-shaped expansion bracket.

[0043] The expanded bottom anchor cable 2 is drilled into the slope surface according to the designed inclination angle and hole depth, and the support frame 2-5 is compressed and stretched to form a "lantern"-shaped expanded body bracket by tensioning the anchor bar body 2-4; grouting is injected into the "lantern" through the drill rod to form a dense expanded body, thereby anchoring the expanded bottom anchor cable 2 in the stable soil layer; after the construction of the lattice retaining wall 1 on the slope surface is completed, prestress is applied to the expanded bottom anchor cable, and the expanded bottom anchor cable 2 and the lattice retaining wall 1 are connected to form a spatial support structure at the anchor inclined support 6 by the anchor device 7, so that the unstable soil on the slope surface is anchored in the surrounding stable soil layer.

[0044] Furthermore, a limit ring 2-9 is provided on the core tube 2-6, and the limit ring 2-9 is located on the inner side of the collar 2-10 close to the side of the reaming drill bit 2-1, and is used to limit the collar to prevent the collar 2-10 of the support frame 2-5 close to the side of the reaming drill bit 2-1 from moving up during drilling, thereby causing the support frame 2-5 to be stretched and unable to continue drilling.

[0045] Furthermore, a limit spring 2-7 is provided between the two collars 2-10, and the limit spring 2-7 is sleeved on the core tube 2-6. The limit spring 2-7 enables the support frame 2-5 to remain in an unexpanded state during the drilling process.

[0046] Furthermore, after the node rods of the support frame 2-5 are stretched out, they squeeze the surrounding soil to form an expanded cavity. After grouting is injected into the cavity, the node rods act as tendons, which greatly ensures the strength of the expanded section.

[0047] Furthermore, the number of hinge points 2-11 on the collar 2-10 can be appropriately increased or decreased according to the designed bearing capacity.

[0048] Furthermore, the tail of the anchor bar body 2-4 is sequentially covered with a corrugated pipe 3, an anchor plate 4 and a spiral bar 5, and the bottom of the corrugated pipe 3 should penetrate into the slope by 10cm-20cm to prevent the concrete and the anchor bar body 2-4 from being cast as a whole and unable to be tensioned.

[0049] Furthermore, the anchor bracket 6 is formed by pouring concrete with a steel formwork, and is a concentrated force-bearing component of the bottom-enlarged anchor cable 2 on the lattice retaining wall 1 .

[0050] Furthermore, the node rods are preferably in the shape of long plates. When the node rods of the support frame are in a closed state, the node rods can completely wrap around the periphery of the core tube 2-6, so as to increase the effective area of ​​the node rods on the surrounding soil as much as possible and increase the cavity space formed after the support frame is opened as much as possible.

[0051] Embodiment 2

[0052] The specific construction method of using pre-tensioned bottom-enlarged anchor cables to construct a support structure includes the following steps:

[0053] ① Assembling the bottom anchor rod: sequentially connect the hole expansion drill bit 2-1, the body expansion anchor head 2-3 and the anchor bar body 2-4 into a whole;

[0054] ② Anchor hole positioning: Position the anchor hole according to the designed point, and position the drilling rig according to the designed inclination;

[0055] ③ Anchor cable assembly; insert the anchor bar body 2-4 of the bottom anchor cable 2 along the bottom of the drill pipe, and make the collar 2-10 at the rear end of the support frame threadedly connected to the drill pipe;

[0056] ④ Anchor cable drilling and installation; increase anchor bar body 2-4 and drill rod length section by section according to designed hole depth;

[0057] ⑤ Anchor cable pre-tensioning: After the anchor cable is installed, reverse the drill rod to separate it from the bottom anchor cable 2, and tension the anchor bar 2-4 after withdrawing the drill rod 10cm-20cm. During the tensioning of the anchor bar 2-4, the collar 2-10 is subjected to the pressure from the top of the drill rod, so that the support frame 2-5 is stretched to form a "lantern"-shaped enlarged head;

[0058] ⑥ Grouting of the expansion section: grouting into the "lantern" through the drill rod, and after completion, withdraw the drill rod;

[0059] ⑦ Construction of lattice retaining wall 1: After the lattice retaining wall foundation trench is leveled, foundation construction is carried out, and then steel bars are tied and anchor brackets are made (6);

[0060] ⑧ Anchor support 6 construction: insert the corrugated pipe 3, anchor pad 4 and spiral reinforcement 5 into the tail of anchor bar body 2-4 in sequence, install the steel formwork of anchor support 6, and pour concrete;

[0061] ⑨ Apply prestress; after the concrete strength reaches the design strength, the bottom anchor cable 2 is prestressed according to the design requirements and the bottom anchor cable 2 is locked on the anchor inclined support 6 with the anchor 7, and then the anchor is sealed.

[0062] For ease of explanation, spatial relative terms such as "upper", "lower", "left", "right" and the like are used in the embodiments to illustrate the relationship of one element or feature shown in the figure relative to another element or feature. It should be understood that, in addition to the orientation shown in the figure, the spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, the element described as being "under" other elements or features will be positioned "on" other elements or features. Therefore, the exemplary term "under" can include both upper and lower orientations. The device can be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here can be interpreted accordingly.

[0063] Furthermore, relational terms such as “first” and “second” and the like are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0064] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A construction method for constructing a support structure by pre-tensioning and expanding bottom anchor cables, characterized in that: It comprises a hole-enlarging drill bit (2-1), an extrusion joint (2-2), an expanded anchor head (2-3) and an anchor bar body (2-4), wherein the hole-enlarging drill bit (2-1) is connected to the top of the expanded anchor head (2-3), and the anchor bar body (2-4) is connected to the tail of the expanded anchor head (2-3) via the extrusion joint (2-2); The expanded anchor head (2-3) comprises a core tube (2-6) and a support frame (2-5); a raised flange (2-8) is provided on the outer wall of the core tube (2-6) along the longitudinal direction of the core tube; the reaming drill bit (2-1) is fixedly mounted on the top end of the core tube (2-6); and the extrusion joint (2-2) is fixedly connected to the rear end of the core tube (2-6); the support frame (2-5) comprises two sleeve rings (2-10) and a plurality of section rods (2-12) connected between the two sleeve rings and distributed along the circumference of the sleeve rings; the two sleeve rings (2-10) are sleeved on the core tube (2-6), one sleeve ring is close to the side of the reaming drill bit (2-1), and the other sleeve ring is close to the side of the extrusion joint (2-2); an external thread is provided on the sleeve ring (2-10) of the support frame (2-5) close to the side of the extrusion joint (2-2) for threaded connection with a drill pipe; each sleeve ring (2-10) is provided with a plurality of section rods (2-12) connected between the two sleeve rings and distributed along the circumference of the sleeve rings; 10) A plurality of hinge points (2-11) are provided on the outer wall along its circumference at intervals, and the two ends of a single segment rod are respectively hingedly connected to the hinge points of the two sleeve rings, and a hinge point is provided in the middle of the single segment rod; a groove matching the flange (2-8) of the core tube (2-6) is provided on the inner wall of each sleeve ring (2-10); after the sleeve ring (2-10) is sleeved on the core tube (2-6), the sleeve ring (2-10) is installed by matching the groove of the sleeve ring (2-10) with the flange (2-8) of the core tube (2-6), so that the rotational freedom of the sleeve ring (2-10) and the core tube (2-6) can be limited but the axial sliding freedom can not be limited, so that when the drill rod is drilling, the expansion anchor head (2-3) and the core tube (2-6) can be drilled synchronously, and when the two sleeve rings (2-10) slide relatively close to each other on the core tube (2-6), the segment rod between the two sleeve rings can be stretched to form a "lantern"-shaped expansion bracket; The construction method of constructing a support structure by pre-tensioning and expanding the bottom anchor cable comprises the following steps: ① sequentially connecting the hole expansion drill bit (2-1), the expanded anchor head (2-3) and the anchor bar body (2-4) into a whole; ② Locate the anchor holes according to the designed points and position the drilling rig according to the designed inclination angle; ③ Insert the anchor bar body (2-4) of the bottom anchor cable (2) along the bottom of the drill pipe, and thread the collar (2-10) at the rear end of the support frame to the drill pipe; ④ Drilling is carried out, during which the anchor bar (2-4) and the drill rod length are gradually increased according to the designed hole depth; ⑤ After the anchor cable is installed, the drill rod is reversed to separate it from the bottom anchor cable (2). After the drill rod is withdrawn 10 cm to 20 cm, the anchor bar body (2-4) is tensioned. During the tensioning of the anchor bar body (2-4), the collar (2-10) is subjected to the pressure from the top of the drill rod, so that the support frame (2-5) is stretched to form a "lantern"-shaped enlarged head; ⑥ Use the drill rod to inject grout into the "lantern" shaped enlarged head, and withdraw the drill rod after completion; ⑦ Construction of lattice retaining wall (1): After the lattice retaining wall foundation trench is leveled, foundation construction is carried out, followed by tying steel bars and making anchor brackets (6); ⑧ Anchor support (6) construction: insert the corrugated pipe (3), anchor pad (4) and spiral reinforcement (5) into the tail of the anchor reinforcement body (2-4) in sequence, install the anchor support (6) steel formwork, and pour concrete; ⑨ Apply prestress; after the concrete strength reaches the design strength, prestress the bottom anchor cable (2) according to the design requirements and lock the bottom anchor cable (2) on the anchor bracket (6) with an anchor (7), and then perform anchor sealing.

2. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1 is characterized in that: The number of the flanges (2-8) is two, and the two flanges (2-8) are symmetrically arranged with respect to the diameter of the core tube.

3. The pre-tensioned bottom-expanding anchor cable according to claim 1, characterized in that: Each section rod is composed of two sub-section rods of equal length that are hinged and butt-jointed.

4. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: A limit ring (2-9) is provided on the core tube (2-6), and the limit ring (2-9) is located on the inner side of the collar (2-10) close to the side of the reaming drill bit (2-1), and is used to limit the collar, so as to prevent the collar (2-10) close to the side of the support frame (2-5) from moving upward during drilling, thereby causing the support frame (2-5) to be stretched and unable to continue drilling.

5. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: A limit spring (2-7) is arranged between the two collars (2-10), and the limit spring (2-7) is sleeved on the core tube (2-6). The limit spring (2-7) enables the support frame (2-5) to remain in an un-spread state during the drilling process.

6. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: After the node rods of the support frame (2-5) are stretched out, they squeeze the surrounding soil to form an expanded cavity. After grouting is injected into the cavity, the node rods act as tendons, thereby greatly ensuring the strength of the expanded section.

7. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: The number of hinge points (2-11) on the collar (2-10) increases or decreases according to the design bearing capacity.

8. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: A corrugated pipe (3), an anchor plate (4) and a spiral reinforcement (5) are sequentially mounted on the tail of the anchor reinforcement body (2-4) and concrete is poured. The bottom of the corrugated pipe (3) penetrates 10 cm to 20 cm into the slope surface to prevent the concrete and the anchor reinforcement body (2-4) from being poured as a whole and unable to be tensioned.

9. The construction method of constructing a support structure by pre-tensioning and expanding bottom anchor cables according to claim 1, characterized in that: The section rods are in the shape of long plates. When the section rods of the support frame are in a closed state, the section rods can completely wrap around the periphery of the core tube.

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