A recyclable prestressed anchor cable for foundation pit support and its construction method

Abstract

This invention discloses a recyclable prestressed anchor cable for foundation pit support and its construction method. It includes a detachable anchor plate and a rubber ring fixed to the outside of the detachable anchor plate. The detachable anchor plate has grouting through holes, injection through holes, and steel strand installation through holes. A conical breaker is installed inside the injection through hole, and a steel strand is inserted through the steel strand installation through hole, with a steel strand compression head fixed to the insertion end of the steel strand. A steel strand sleeve is provided outside the steel strand, with one end of the sleeve fixed to the detachable anchor plate. The conical breaker is a hollow tube, and an injection pipe is also installed inside the conical breaker. The detachable anchor plate includes a left anchor plate and a right anchor plate, with the injection through holes and steel strand installation through holes evenly distributed on the left and right anchor plates. This invention has a simple structure and can realize the recycling of most of the equipment, including the steel strand, steel strand compression head, conical breaker, and injection pipe. The recycled components can be reused, improving the use value of the anchor cable.

Description

Technical Field

[0001] This invention relates to the field of civil engineering foundation pit support, specifically to a recyclable prestressed anchor cable for foundation pit support and its construction method. Background Technology

[0002] Prestressed anchor cables are widely used in civil engineering, primarily for slope protection after roadbed excavation in road projects, and for supporting the inner walls of foundation pits during the excavation of building and large structures. They are also extensively used in coal mines. Early prestressed anchor cables were generally non-recoverable, permanently embedded in the soil. In foundation pit support, the long-term presence of various anchor cable components in the soil can lead to corrosion, polluting groundwater and other natural resources, and causing problems for subsequent construction of adjacent buildings, thus becoming an obstacle to construction. Furthermore, the support function of prestressed anchor cables is no longer needed during the later backfilling of the foundation pit. Therefore, the invention of recyclable prestressed anchor cables for foundation pit support is essential, as it benefits both the protection of the natural environment and resources and cost savings.

[0003] Currently available mechanically recyclable prestressed anchor cables contain precision components such as detachable threaded connectors and small transmission gears. These components require high precision to manufacture and necessitate high-standard machine tools for processing. The anchor cables involve numerous installation procedures. During recycling, generally only the steel strands can be recovered. Extensive manual labor is required to rotate or shake the steel strands, which can be tens of meters long, to remove them from the anchorage, making the process difficult and time-consuming. Furthermore, during recycling, the internal precision mechanical components are prone to deformation and jamming due to improper operation. Mechanically recyclable prestressed anchor cables also include a U-shaped recyclable type. Because the bending radius of the steel strand at the U-shaped device at the anchoring end is very small, when the anchor cable is long, it is difficult to pull out manually, often requiring the use of jacks for slow extraction, thus extending the recycling time.

[0004] For thermoplastic recyclable prestressed anchor cables, compared to the aforementioned mechanical type, it is necessary to manufacture special anchorages with embedded thermoplastic material, and add components such as electric heating rings, conductors, and protective conduits. During recycling, only the steel strands can be recovered, resulting in a lower recovery rate. The precision requirements for adding thermoplastic material into the anchorage and installing the conductors are high. If the installation is not in place, or if the conductors are damaged or broken, or the joints fall off, or the thermoplastic material leaks or shifts during the anchor cable drilling process due to collisions or squeezing, the conductors will not be energized, the thermoplastic material will be insufficient, and the melting position will be inaccurate, resulting in ineffective melting. In such cases, manual and mechanical methods must be used to recover the anchor cable, or it may even be impossible to recover it at all.

[0005] In summary, existing recyclable anchor cable products suffer from high manufacturing and installation precision requirements and low recycling rates. This makes them difficult to operate during construction, and some steel strands and related equipment cannot be recycled or reused multiple times. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a recyclable prestressed anchor cable for foundation pit support and its construction method.

[0007] To achieve the aforementioned objectives, the technical solution adopted by this invention is as follows: It includes a detachable anchor plate and a rubber ring fixed to the outside of the detachable anchor plate. The detachable anchor plate is provided with a grouting through hole, a grouting through hole, and a steel strand installation through hole. A conical breaker is installed inside the grouting through hole. A steel strand is inserted through the steel strand installation through hole, and a steel strand extrusion head is fixed to the insertion end of the steel strand. A steel strand sleeve is provided outside the steel strand, and one end of the steel strand sleeve is fixed to the detachable anchor plate. The conical breaker is a... The empty pipe and the conical rupture device are equipped with grouting pipes; the steel strand extrusion head is cylindrical, and the contact end between the steel strand extrusion head and the separable anchor plate is flat; the separable anchor plate includes a left anchor plate and a right anchor plate, and the grouting through holes and steel strand installation through holes are evenly distributed on the left anchor plate and the right anchor plate, and the left anchor plate and the right anchor plate are also provided with several grouting through holes respectively; one end of the steel strand is fixed to one end of the separable anchor plate through the steel strand extrusion head, and the other end of the steel strand is fixed to the anchor beam through the external clamp anchor.

[0008] Furthermore, the conical rupture device includes a straight cylindrical section, a guide section, and an enlarged section connected in sequence. The conical rupture device is a hollow tube, and a grouting pipe is fixed inside the conical rupture device. The grouting through hole includes a guide straight hole and a guide hole connected to the guide straight hole. The slope of the guide hole is the same as that of the guide section. A chamfer is provided on the fixed side of the steel strand installation through hole for installing steel strands.

[0009] Furthermore, the left and right anchor plates are semi-circular in shape, and the left and right anchor plates are fitted together to form a cylindrical shape; there is one grouting through hole and two steel strand installation through holes, which are symmetrically distributed on both sides of the grouting through hole, and the grouting through hole and steel strand installation through hole are evenly divided and set on the left and right anchor plates.

[0010] Furthermore, a rubber plug is provided between the guide section, the enlarged section and the grouting pipe. The rubber plug has a through hole for installing the grouting pipe. The rubber plug has the same shape as the conical rupture device, and the outer diameter of the rubber plug is less than or equal to the inner diameter of the conical rupture device.

[0011] Furthermore, the steel strand sleeve is bonded and fixed to the detachable anchor plate.

[0012] Furthermore, a baffle is provided at the end of the enlarged section, and a through hole is provided on the baffle for installing the grouting pipe. The baffle is sealed to the enlarged section and the grouting pipe respectively.

[0013] Furthermore, the rubber ring is made of water-absorbing and expanding rubber, and the inner ring surface of the rubber ring is bonded and fixed to the outside of the separable anchor plate.

[0014] Furthermore, the side of the separable anchor plate that is in contact with the rubber ring is a frustum; the inner ring of the rubber ring is a frustum, the outer ring is a ring, and the smaller end of the radius of the frustum is located at the insertion end of the separable anchor plate.

[0015] Furthermore, the rubber ring is provided with several evenly distributed strip-shaped opening grooves, which are located at the corners of the outer ring surface and the upper side surface of the rubber ring; the vertical cross-section of the strip-shaped opening grooves is triangular.

[0016] The construction method for recyclable prestressed anchor cables includes the following steps:

[0017] S1: Assemble prestressed anchor cables:

[0018] First, glue and fix the steel strand sleeve into the steel strand installation through hole of the separable anchor plate. Then, pass the steel strand through the steel strand sleeve and the separable anchor plate, and fix the inserted end of the steel strand with the steel strand extrusion head. Separate the separable anchor plate, install the conical breaker through the grouting through hole, and then use a rubber ring to merge and fix the separable anchor plate.

[0019] S2: Drilling the foundation pit, installing prestressed anchor cables, and grouting:

[0020] Before excavating the foundation pit, confirm the pit depth, diameter, and excavation angle for the non-recoverable anchor cables; excavate within the designed area of ​​the foundation pit, and when excavating to the designed elevation of the prestressed anchor cables, use a drilling rig to form a hole; after the hole is formed, place the assembled prestressed anchor cables into the designed position in the hole, and perform grouting operations from the outside through the grouting pipe. When one side of the separable anchor plate is fully grouted, the grout enters the foundation pit on the other side of the separable anchor plate through the grouting through hole on the separable anchor plate until the foundation pit is fully grouted;

[0021] S3: Install anchor beams and tension steel strands:

[0022] Once the grout has solidified to the design strength, the steel strands are tensioned. When tensioned to the design tonnage, they are anchored to the anchor beam using wedge anchors to support the foundation pit and complete the installation of the prestressed anchor cable.

[0023] S4: Continue the subsequent foundation pit excavation, repeat S1-S3, and complete the installation of all prestressed anchor cables;

[0024] S5: Backfilling of the foundation pit and recovery of prestressed anchor cables:

[0025] At the tensioning end, the conical breaker is tensioned using tensioning equipment, causing it to move forward. The conical breaker expands the separable anchor plate, compressing the outer rubber ring and causing it to deform. The conical breaker continuously widens the gap between the two anchor plates in the separable anchor plate until it can be pulled out of the grouting hole. Under the tension force, the steel strand retracts into the steel strand sleeve, and is then manually pulled out and retrieved. The calculation method for the retraction amount of the un-tensioned steel strand under a certain internal tension force during anchor release is as follows:

[0026]

[0027] In the above formula, F represents the internal tension of the steel strand; L represents the calculated length of the steel strand; and EA represents the tensile stiffness of the steel strand.

[0028] The present invention has the following advantages:

[0029] 1. This invention achieves the support of the inner wall of the foundation pit through the combination of steel strand, steel strand sleeve, separable anchor plate, rubber ring, steel strand extrusion head, conical breaker, grouting pipe and wedge anchor, and realizes the recycling and reuse of most of the anchor cable structure by utilizing the corresponding functions of the components composed of separable anchor plate, rubber ring and conical breaker.

[0030] 2. This invention can provide effective pre-stress to the inner wall of the foundation pit, thus playing a supporting role; the structure of this invention is simple, and it is not prone to large deformation during service, and it is not prone to problems such as the steel strand getting stuck and unable to be recycled during recycling.

[0031] 3. In this invention, when the conical breaker is tensioned, the detachable anchor plate at the fixed end is opened. The untensioned steel strand and its extrusion head automatically detach from the detachable anchor plate at the fixed end under the action of internal tension force and enter the PVC sleeve, where it can be directly dragged out of the hole. This method is simple, has high recovery reliability, and good stability, avoiding the difficult operation of manually rotating or shaking the steel strand for anchor removal.

[0032] 4. Except for the detachable anchor plate and rubber ring, the rest of the anchor cable assembly can be recycled and reused, with a high recycling rate. This invention can realize the recycling of most of the tools such as steel strands, steel strand extrusion heads, conical breaker and grouting pipe. The recycled parts can be reused, which improves the use value of anchor cables, saves materials and reduces costs.

[0033] 5. After simple slag removal, the recycled components of this invention only need to be covered with a PVC pipe after the recycled steel strand and its extrusion head are put back on, and combined with the recycled conical breaker, they can be reassembled and reused with the replaced plastic grouting pipe and the fixed end detachable anchor plate, which increases the number of times the steel strand can be reused and is more economical.

[0034] 6. This invention eliminates the need for designing and customizing special anchors, thus avoiding the process of casting new anchors in a factory workshop. The detachable anchor plate can be fabricated on-site. Existing anchor plates can be simply cut in half, modified, and fitted with rubber rings to assemble into a detachable anchor plate with a fixed end.

[0035] 7. The overall structure of the anchor cable is not complicated, the assembly is simple, no professional training is required, and it is quick to learn. During the insertion into the hole and tensioning process, the steel strand at the fixed end will not separate from or fall off the separable anchor plate due to the use of a squeezed compression sleeve, and there will be no jamming of the steel strand with the internal components.

[0036] 8. During the recycling process, the present invention utilizes a tensioning device to tension the conical breaker, causing the separable anchor plate to open a sufficiently large gap. This allows the untensioned steel strands to automatically retract and detach from the separable anchor plate under the tension force inside the steel bundle, entering the PVC sleeve and then being directly dragged out of the hole. This method is simple, has high recycling reliability, good stability, and fast recycling speed.

[0037] 9. The anchor cable of the present invention is not anchored by clamps, but by end bearing pressure. Therefore, the non-recyclable separable anchor plate can be made very thin, so the cost of the separable anchor plate is lower and the non-recyclable part has less environmental impact.

[0038] 10. After simple slag removal, the recovered components of this invention only need to be fitted with a steel strand sleeve over the recovered steel strand and its extrusion head, and combined with the recovered conical breaker, to be reassembled and reused with the replaced grouting pipe and detachable anchor plate. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the external shape of the present invention. Figure 1 ;

[0040] Figure 2 This is a schematic diagram of the external shape of the present invention. Figure 2 ;

[0041] Figure 3 This is a front view of the present invention;

[0042] Figure 4 for Figure 3 BB cross-section diagram in the middle;

[0043] Figure 5 This is a schematic diagram illustrating the working principle of the present invention;

[0044] Figure 6 for Figure 5 AA section view in the middle;

[0045] Figure 7 This is a schematic diagram of the installation of the present invention.

[0046] The symbols for each component are as follows;

[0047] 1. Rubber ring; 2. Separable anchor plate; 3. Conical breaker; 4. Steel strand; 5. Steel strand extrusion head; 6. Grouting pipe; 7. Grouting through hole; 8. Steel strand sleeve; 9. Mountain; 10. Hole wall; 11. Anchor beam; 12. Wedge anchor. Detailed Implementation

[0048] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0049] like Figures 1 to 7 As shown, the recyclable prestressed anchor cable used for foundation pit support includes a separable anchor plate 2 and a rubber ring 1 fixed to the outside of the separable anchor plate 2. The separable anchor plate 2 is provided with a grouting through hole 7, a grouting through hole and a steel strand installation through hole; a steel strand is installed through the steel strand installation through hole, and a steel strand extrusion head 5 is fixed to the insertion end of the steel strand 4.

[0050] A steel strand sleeve 8 is provided on the outside of the steel strand 4, and one end of the steel strand sleeve 8 is fixed to the detachable anchor plate 2. The steel strand sleeve 8 is bonded and fixed to the detachable anchor plate 2. The steel strand sleeve 8 is preferably a PVC pipe. The steel strand sleeve 8 is bonded and fixed to the lower end of the detachable anchor plate 2 and is concentrically arranged with the steel strand installation through hole.

[0051] A conical breaker 3 is installed inside the grouting through hole. The conical breaker 3 is a hollow tube, and a grouting pipe 6 is also installed inside the conical breaker 3. The grouting pipe 6 is preferably a plastic flexible tube. The steel strand extrusion head 5 is cylindrical, and the contact end between the steel strand extrusion head 5 and the separable anchor plate 2 is flat. The conical breaker 3 includes a straight cylindrical part, a guide part, and an enlarged part connected in sequence. The conical breaker 3 is a hollow tube, and the grouting pipe 6 is fixed inside the conical breaker 3. The grouting through hole includes a guide straight hole and a guide hole connected to the guide straight hole. The slope of the guide hole is the same as that of the guide part. A chamfer is provided on the fixed side of the steel strand installation through hole for installing the steel strand 4. A partition is provided at the end of the enlarged part. The partition has a through hole for installing the grouting pipe 6, and the partition is sealed to the enlarged part and the grouting pipe 6 respectively.

[0052] The separable anchor plate 2 includes a left anchor plate and a right anchor plate. Grouting through holes and steel strand installation through holes are evenly distributed on the left anchor plate and the right anchor plate. Several grouting through holes 7 are also provided on the left anchor plate and the right anchor plate respectively. The left anchor plate and the right anchor plate are semi-circular in shape and are fitted together to form a cylinder. There is one grouting through hole and two steel strand installation through holes. The two steel strand installation through holes are symmetrically distributed on both sides of the grouting through hole. The grouting through hole and the steel strand installation through holes are evenly distributed on the left anchor plate and the right anchor plate.

[0053] In this embodiment, a rubber plug is provided between the guide section, the enlarged section, and the grouting pipe 6. The rubber plug has a through hole for installing the grouting pipe 6. The rubber plug has the same shape as the conical breaker 3, and the outer diameter of the rubber plug is less than or equal to the inner diameter of the conical breaker 3. The rubber plug can provide a certain degree of support for the inner wall of the conical breaker 3, and at the same time has a certain degree of elasticity, which can play a certain role in buffering and absorbing shock when the conical breaker 3 impacts the separable anchor plate 2, while also providing a certain degree of support and protection for the grouting pipe 6.

[0054] In this embodiment, the rubber ring 1 is made of water-absorbing and expanding rubber. The inner ring surface of the rubber ring 1 is bonded and fixed to the outside of the separable anchor plate 2. The upper and lower sides of the rubber ring 1 are in contact with the concrete, and the outer ring surface of the rubber ring 1 is in contact with the pit hole. The rubber ring 1 absorbs water from the concrete and soil, causing the upper and lower sides and the outer ring surface of the rubber ring 1 to absorb water and expand. The inner ring surface of the rubber ring 1 is in contact with the separable anchor plate 2. Therefore, the inner ring surface of the rubber ring 1 cannot absorb water, so the elastic force provided remains unchanged. However, the upper and lower sides and the outer ring surface of the rubber ring 1 absorb water and expand, so the elastic force provided will be reduced accordingly. Thus, the elastic binding force of the entire rubber ring 1 on the separable anchor plate 2 is reduced. When the conical breaker 3 is pulled out, it is more conducive to the pull-out of the conical breaker 3. At the same time, before the conical breaker 3 is pulled out, a certain prestress is provided to tighten the separable anchor plate 2, so that the steel strand 4 is always under tension and the normal operation of the steel strand 4 is not affected.

[0055] In this embodiment, the side of the separable anchor plate 2 that is in contact with the rubber ring 1 is a frustum surface; the inner ring surface of the rubber ring 1 is a frustum surface, and the outer ring surface of the rubber ring 1 is a ring surface, with the smaller end of the radius of the frustum surface located at the insertion end of the separable anchor plate 2. The outer frustum surface of the separable anchor plate 2, together with the inner ring surface of the rubber ring 1, can play a role in the aggregation and fixation of the separable anchor plate 2, and can fix the left and right anchor plates with the conical breaker 3 and the steel strand 4 into a whole. When the rubber ring 1 with the inner ring surface of the frustum is subjected to radial force, that is, the decomposition force on the separable anchor plate 2 when the conical breaker 3 is pulled out, the rubber ring 1 is prone to directional deformation, making it easier to retract the conical breaker 3, but without affecting the normal prestressed anchoring of the steel strand 4 and the steel strand extrusion head 5.

[0056] In this embodiment, the rubber ring 1 is provided with several evenly distributed strip-shaped opening grooves, which are located at the corners of the outer ring surface and the upper side surface of the rubber ring 1; the vertical cross-section of the strip-shaped opening grooves is triangular. The strip-shaped opening grooves facilitate upward deformation at the outer ring of the rubber ring 1, thereby making it easier for the conical breaker 3 to trigger the separable anchor plate 2 and the rubber ring 1, and making it easier to remove the conical breaker 3 and the steel strand 4.

[0057] The construction method for recyclable prestressed anchor cables includes the following steps:

[0058] S1: Assemble prestressed anchor cables:

[0059] First, the steel strand sleeve 8 is glued and fixed in the steel strand installation through hole of the separable anchor plate 2. Then, the steel strand 4 is passed through the steel strand sleeve 8 and the separable anchor plate 2, and the insertion end of the steel strand 4 is fixed with the steel strand extrusion head 5. The separable anchor plate 2 is separated, the conical breaker 3 is installed through the grouting through hole, and then the separable anchor plate 2 is joined and fixed with the rubber ring 1.

[0060] S2: Drilling the foundation pit, installing prestressed anchor cables, and grouting:

[0061] Before excavating the foundation pit, confirm the pit depth, diameter, and excavation angle for the non-recoverable anchor cables; excavate within the designed area of ​​the foundation pit, and when excavating to the designed elevation of the prestressed anchor cables, use a drilling rig to form a hole; after the hole is formed, place the assembled prestressed anchor cables into the designed position in the hole, and perform grouting operations from the outside through the grouting pipe. When one side of the separable anchor plate 2 is fully grouted, the grout enters the foundation pit on the other side of the separable anchor plate from the grouting through hole 7 on the separable anchor plate 2 until the foundation pit is fully grouted;

[0062] S3: Install anchor beam 11 and tension the steel strands:

[0063] Once the grout has solidified to the design strength, the steel strand 4 is tensioned. When tensioned to the design tonnage, it is anchored to the anchor beam 11 using the wedge anchor 12 to support the foundation pit and complete the installation of the prestressed anchor cable.

[0064] S4: Continue the subsequent foundation pit excavation, repeat S1-S3, and complete the installation of all prestressed anchor cables;

[0065] S5: Backfilling of the foundation pit and recovery of prestressed anchor cables:

[0066] At the tensioning end, the conical breaker 3 is tensioned using tensioning equipment, causing it to move forward. The conical breaker 3 expands the separable anchor plate 2, compressing the outer rubber ring 1 and causing it to deform. The conical breaker 3 continuously widens the gap between the two anchor plates in the separable anchor plate 2 until it can be pulled out of the grouting hole. Under tension, the steel strand 4 retracts into the steel strand sleeve 8, and is subsequently manually pulled out and retrieved. The calculation method for the retraction amount of the un-tensioned steel strand under a certain internal tension during anchor release is as follows:

[0067]

[0068] In the above formula, F represents the internal tension force of the steel strand; L represents the calculated length of the steel strand; and EA represents the tensile stiffness of the steel strand. For example, a 10m long 2Φs15.2 steel strand with an elastic modulus of , under an internal tension force of 20t, the amount of retraction during anchorage removal is:

[0069]

Claims

1. A recyclable prestressed anchor cable for foundation pit support, characterized in that: It includes a separable anchor plate (2) and a rubber ring (1) fixed to the outside of the separable anchor plate (2). The separable anchor plate (2) is provided with a grouting through hole (7), a grouting through hole and a steel strand installation through hole. A conical breaker (3) is installed in the grouting through hole. A steel strand (4) is installed through the steel strand installation through hole. A steel strand extrusion head (5) is fixed to the insertion end of the steel strand (4). A steel strand sleeve (8) is provided outside the steel strand (4). One end of the steel strand sleeve (8) is fixed to the separable anchor plate (2). The conical breaker (3) is a hollow tube. A grouting pipe (6) is also provided inside the conical breaker (3). The steel strand extrusion head (5) is cylindrical. The contact end of the steel strand extrusion head (5) with the separable anchor plate (2) is a plane. The separable anchor plate (2) includes a left anchor plate and a right anchor plate. The grouting through holes and steel strand installation through holes are evenly divided and arranged on the left anchor plate and the right anchor plate. The left anchor plate and the right anchor plate are also provided with a number of grouting through holes (7). One end of the steel strand (4) is fixed to one end of the separable anchor plate (2) by the steel strand extrusion head (5), and the other end of the steel strand (4) is fixed to the anchor beam (11) by the external clamp anchor (12). The rubber ring (1) is water-absorbing and expanding rubber, and the inner ring surface of the rubber ring (1) is bonded and fixed to the outside of the separable anchor plate (2); The upper and lower sides of the rubber ring (1) are in contact with the concrete, and the outer ring surface of the rubber ring (1) is in contact with the pit hole. The rubber ring (1) absorbs water from the concrete and soil, causing the upper and lower sides and the outer ring surface of the rubber ring (1) to absorb water and expand. The inner ring surface of the rubber ring (1) is in contact with the separable anchor plate (2).

2. The recyclable prestressed anchor cable for foundation pit support according to claim 1, characterized in that, The conical rupture device (3) includes a straight cylindrical part, a guide part and an enlarged part connected in sequence. The conical rupture device (3) is a hollow tube. The grouting pipe (6) is fixed inside the conical rupture device (3). The grouting through hole includes a guide straight hole and a guide hole connected to the guide straight hole. The slope of the guide hole is the same as that of the guide part. The fixed side of the steel strand installation through hole is provided with a chamfer for installing the steel strand (4).

3. The recyclable prestressed anchor cable for foundation pit support according to claim 1, characterized in that, The left and right anchor plates are semi-circular in shape and are fitted together to form a cylinder. There is one grouting through hole and two steel strand installation through holes. The two steel strand installation through holes are symmetrically distributed on both sides of the grouting through hole. The grouting through hole and the steel strand installation through hole are evenly divided and arranged on the left and right anchor plates.

4. The recyclable prestressed anchor cable for foundation pit support according to claim 2, characterized in that, A rubber plug is provided between the guide part, the enlarged part and the grouting pipe (6). The rubber plug is provided with a through hole for installing the grouting pipe (6). The rubber plug has the same shape as the conical rupture device (3). The outer diameter of the rubber plug is less than or equal to the inner diameter of the conical rupture device (3).

5. The recyclable prestressed anchor cable for foundation pit support according to claim 1, characterized in that, The steel strand sleeve (8) is bonded and fixed to the separable anchor plate (2).

6. The recyclable prestressed anchor cable for foundation pit support according to claim 2, characterized in that, The end of the enlarged part is provided with a partition plate, and the partition plate is provided with a through hole for installing the grouting pipe (6). The partition plate is sealed to the enlarged part and the grouting pipe (6) respectively.

7. The recyclable prestressed anchor cable for foundation pit support according to claim 1, characterized in that, The side of the separable anchor plate (2) that is in contact with the rubber ring (1) is a frustum; the inner ring surface of the rubber ring (1) is a frustum, the outer side of the rubber ring (1) is a ring, and the smaller end of the radius of the frustum of the rubber ring (1) is located at the insertion end of the separable anchor plate (2).

8. The recyclable prestressed anchor cable for foundation pit support according to claim 7, characterized in that, The rubber ring (1) is provided with a number of evenly distributed strip-shaped opening grooves, which are located at the corners of the outer ring surface and the upper side surface of the rubber ring (1); the vertical cross-section of the strip-shaped opening groove is triangular.

9. A construction method for a recyclable prestressed anchor cable as described in any one of claims 1-8, characterized in that, The steps include the following: S1: Assemble prestressed anchor cables: First, bond and fix the steel strand sleeve (8) into the steel strand installation through hole of the separable anchor plate (2), then pass the steel strand (4) through the steel strand sleeve (8) and the separable anchor plate (2), and fix the insertion end of the steel strand (4) with the steel strand extrusion head (5); separate the separable anchor plate (2), install the conical breaker (3) through the grouting through hole, and then use the rubber ring (1) to merge and fix the separable anchor plate (2); S2: Drilling the foundation pit, installing prestressed anchor cables, and grouting: Before excavating the foundation pit, confirm the depth, diameter and excavation angle of the foundation pit for the non-recoverable anchor cable; excavate within the design range of the foundation pit, and when excavating to the design elevation of the prestressed anchor cable, use a drilling rig to form a hole; after the hole is formed, place the assembled prestressed anchor cable into the design position in the hole, and perform grouting operation from the outside through the grouting pipe. When one side of the separable anchor plate (2) is grouted to the fullness, the grout enters the foundation pit on the other side of the separable anchor plate from the grouting through hole (7) on the separable anchor plate (2) until the foundation pit is grouted to the fullness. S3: Install anchor beam (11), tension steel strand: Once the grout has solidified to the design strength, the steel strand (4) is tensioned. When tensioned to the design tonnage, it is anchored to the anchor beam (11) using a wedge anchor (12) to support the foundation pit and complete the installation of the prestressed anchor cable. S4: Continue the subsequent foundation pit excavation, repeat S1-S3, and complete the installation of all prestressed anchor cables; S5: Backfilling of the foundation pit and recovery of prestressed anchor cables: At the tensioning end, the conical breaker (3) is tensioned using tensioning equipment, causing the conical breaker (3) to move forward. The conical breaker (3) expands the separable anchor plate (2), squeezing the outer rubber ring (1) to deform it. The conical breaker (3) continuously widens the gap between the two anchor plates in the separable anchor plate (2) until the conical breaker (3) can be pulled out from the grouting hole. Under the action of tension force, the steel strand (4) retracts into the steel strand sleeve (8), and then the steel strand (4) is manually pulled out and retrieved. The calculation method for the amount of retraction of the steel strand that was not released during anchoring under a certain internal tension force is as follows: In the above formula, F This indicates the internal tension of the steel strand; L Indicates the calculated length of the steel strand; EA This indicates the tensile stiffness of the steel strand.

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