CN112253199B

CN112253199B - Anchor cable with hole bottom yielding device and construction method thereof

Info

Publication number: CN112253199B
Application number: CN202011171732.9A
Authority: CN
Inventors: 吴航通; 吕志平; 项小珍; 王勇; 周彪; 沈艳芳; 汪运来
Original assignee: Hangzhou Dodrive Engineering Materials Co ltd
Current assignee: Hangzhou Dodrive Engineering Materials Co ltd
Priority date: 2020-10-28
Filing date: 2020-10-28
Publication date: 2022-07-05
Anticipated expiration: 2040-10-28
Also published as: CN112253199A

Abstract

The invention discloses an anchor cable with a hole bottom yielding device and a construction method thereof, and relates to the technical field of rock-soil anchoring and engineering support, wherein the anchor cable with the hole bottom yielding device comprises a steel strand and a supporting base plate, the front part of the steel strand is sleeved with an anchor pipe, and the steel strand penetrates through the anchor pipe and then is scattered into a plurality of steel wires; wherein, the inner layer steel wire is sleeved with the conical wedge pipe, and the inner layer steel wire, the conical wedge pipe, the outer layer steel wire and the inner cavity of the anchor pipe form extrusion fit; the rear part of the steel strand is matched with the supporting base plate through a locking piece. The invention can be used for controlling the initial deformation by stretching to generate prestress, playing a function of yielding and sliding when the stress exceeds a certain value, absorbing the energy released by the stratum, and grouting to fully bond the anchor cable and the stratum, thereby improving the safety of the anchor cable and the durability of long-term operation.

Description

Anchor cable with hole bottom yielding device and construction method thereof

Technical Field

The invention relates to the technical field of rock and soil anchoring and engineering supporting, in particular to an anchor cable with a hole bottom yielding device and a construction method thereof.

Background

The prestressed anchor cable is flexible and is formed by high-strength steel strands, riggings and other accessories, and is used for mining engineering at first. The steel strand is a flexible steel bar twisted into rope shape by a plurality of strands of high-strength steel wires, 3 strands, 7 strands and 19 strands are commonly used. The diameter of the steel wire is commonly selected from phi 4, phi 5, phi 6 and the like, the steel wire is a high-strength steel wire formed by cold drawing carbon steel, the most commonly used ultimate tensile strength in the market at present is 1860MPa, and the steel wire is developed towards the direction of higher strength so as to save steel. The high-strength steel strand is generally a 7 phi 5 steel strand as a prestressed reinforcement steel strand with a nominal diameter of phi 15.2 in a prestressed concrete structure. The diameter of a single steel strand is commonly used in mining engineering, and the diameter of 7 strands and 19 strands of steel strands are commonly used as anchor bars and is generally phi 15.2-phi 21.8 mm; according to the national standard GB/T5224-2014, for example, the ultimate tensile strength 1860MPa of steel wires is, the nominal diameter of 7 phi 5-steel strands is phi 15.2, the maximum tension of the whole steel strand is 288KN, the nominal diameter of 1 multiplied by 19 (1+9+9) S steel strands is phi 21.8, and the maximum tension of the whole steel strand is 583 KN.

The single steel strand has the advantages of being much larger in bearing capacity than common steel bars, flexible and bendable, beneficial to small machine tool operation in narrow roadway engineering, capable of forming quick support by matching with resin cartridges, generally 1.8-3.0 m in length for mining, 0.5-0.8 m in length at the bottom of a hole, capable of achieving anchoring requirements by adopting 1-2 sections of resin cartridges, and convenient to construct. The general method is to punch a hole at a designated position, put in a resin cartridge, insert a steel strand, rotate the steel strand at a high speed with a special machine to fully stir the resin at the bottom of the hole, so that the steel strand and the rock hole are fully bonded and anchored. The working strength is achieved by adopting a quick resin cartridge usually for 5-10 min, then the steel strand is stretched on the rock bearing surface, and is locked by a rigging to form prestress, so that the installation is completed.

The above mentioned mines are usually bonded only at the end anchor resin anchors and not near the port section. If the length of the steel strand is 3.0m, the anchoring length of the resin cartridge at the bottom end part of the hole is 0.8m, the length of the part close to the outside reaches 2.2m, and the part is not bonded with the rock hole, so that the exposed steel strand is corroded in the rock hole, and the risk of corrosion, breakage and failure of the steel strand exists after long-term use. Meanwhile, the unbonded structure can also reduce the overall synergy between the steel strand anchor bars and the rock mass, and is not beneficial to the effect of forming a pressure ring through supporting at reasonable intervals. And therefore is used only as a temporary project.

On the other hand, in a high ground stress stratum, a hard rock stratum has special engineering problems such as rock burst, large deformation of soft rock or broken stratum and the like. For processing the special geological phenomena, various yielding anchor rods appear so as to solve the problem of support safety under high ground stress. A specific yielding device is arranged in the yielding anchor rod (cable), when the supported structure is greatly deformed, the yielding device enables the anchor rod (cable) body to generate deformation adaptive to the geotechnical body, the anchor rod (cable) body is prevented from being broken and losing efficacy, the supporting effect is kept, and the specific yielding anchor rod can effectively control complicated and variable large-deformation geotechnical engineering which is difficult to support. In recent years, various yielding anchor rods with constant-resistance deformation are continuously developed and applied to side slopes, underground engineering or mining roadway support engineering to solve the problem of large deformation of the stratum caused by weak surrounding rocks.

For permanent engineering supports, it is necessary that the support meet the long-term durability problem. Meanwhile, the supporting cost is much higher than that of the common ground layer, so that the anchor rod has good performance, long-term working durability and cost reduction, which are long-sought targets.

Disclosure of Invention

The invention provides an anchor cable with a hole bottom yielding device, wherein the hole bottom yielding device can be tensioned to generate prestress to control initial deformation, plays a function of yielding and sliding when the stress exceeds a certain value, absorbs the energy released by a stratum, can be grouted to fully bond the anchor cable and the stratum, and improves the safety of the anchor cable and the durability of long-term operation.

An anchor cable with a hole bottom yielding device comprises a steel strand and a supporting base plate, wherein an anchor pipe is sleeved at the front part of the steel strand, and the steel strand penetrates through the anchor pipe and then is scattered into a plurality of steel wires; wherein, the inner layer steel wire is sleeved with the conical wedge pipe, and the inner layer steel wire, the conical wedge pipe, the outer layer steel wire and the inner cavity of the anchor pipe form extrusion fit; the rear part of the steel strand is matched with the supporting base plate through a locking piece.

The outer layer steel wire the steel strand wires form a stirring head after extending out of the front end of the anchor pipe, and the front part of the steel strand wires, the anchor pipe and the conical wedge pipe form a yielding anchor head device.

The anchor cable has the advantages that the hole bottom yielding device is anchored by the resin cartridge and is rapidly anchored to form a supporting force, the anchor cable is used for energy absorption yielding and permanent engineering supporting under the condition of high ground stress, and when a large-tonnage single steel strand scheme (such as a phi 28.6mm steel strand, which can reach over 900 kN) is adopted, the anchor cable can be applied to supporting of large-span underground caverns, side slopes and the like.

Preferably, the anchor pipe is a round straight pipe, and the outer surface of the anchor pipe is a threaded surface or other regular concave-convex surfaces, so that resin anchoring is facilitated.

Preferably, the rear end of the anchor pipe is provided with a positioning piece, and the steel strand penetrates through the positioning piece and the anchor pipe and then is scattered into a plurality of steel wires; the locating piece is formed by extruding the rear end of the anchor pipe, or an independent pin key type braking ring is adopted.

The anchor pipe is matched with the steel strand through extrusion of the conical wedge pipe, the anchor pipe cannot be separated from the steel strand to rotate but can longitudinally slide under certain tension, and the positioning piece is used for limiting the longitudinal sliding distance of the steel strand.

Preferably, the front part of the anchor pipe is provided with at least one longitudinal slot, the length of the slot is not less than 20mm, and not more than 90% of the total length of the anchor pipe. The front part of the anchor pipe is longitudinally grooved, so that the front end of the anchor pipe can be conveniently opened, the anchor pipe is suitable for the solidification time of different types of anchoring agents, and meanwhile, the mechanical matching of the outer wall of the anchor pipe and the wall of a rock hole has the effect similar to that of a shell expansion anchoring head. In the invention, the stirring head can have two structures, the first structure is as follows: the steel strand wires pass through the front end of the anchor pipe and then form a diffusion-shaped stirring head under the extrusion of the conical wedge pipe, and the diffused steel wires are exposed at the front end of the anchor pipe to improve the stirring effect.

The second method is as follows: after the steel strand passes through the front end of the anchor pipe, diffused steel wires formed by extruding the conical wedge pipe are gathered into a bundle through a front end fastener, and a bullet-shaped stirring head is formed.

In the invention, the steel strand can adopt 7 strands of steel wires or 19 strands of steel wires; when 7 strands of steel wires are adopted, the inner layer steel wire and the outer layer steel wire are both one layer; when 19 strands of steel wires are adopted, the inner layer steel wires are two layers, and the outer layer steel wires are one layer.

Preferably, the conical wedge tube is installed by inserting the conical wedge tube into the inner cavity of the anchor tube as completely as possible. Furthermore, the large head end of the conical wedge pipe is flush with the front end surface of the anchor pipe.

Preferably, the locking piece of the invention adopts an anchoring-grouting integrated combined function locking piece, and specifically: the locking piece comprises a locking functional section, a pad seat, a grouting functional section and a connecting section; the pad seat and the grouting functional section are provided with lateral grouting holes, and the inner cavity of the locking piece is used for penetrating and locking a steel strand;

the middle part of the steel strand is sleeved with a grouting isolation sleeve, and a plurality of slurry outlet holes are formed in the grouting isolation sleeve; the front end of the grouting isolation sleeve is close to the rear end face of the anchor pipe, and the rear end of the grouting isolation sleeve is in butt joint with the connecting section of the locking piece; the lateral grouting holes, the inner cavity of the grouting isolation sleeve and the grout outlet form a channel communicated with the inside and the outside.

Furthermore, the locking function section, the pad seat and the grouting function section are of an integral structure or of two split structures.

The grouting isolation sleeve is preferably a corrugated pipe, can be made of stainless steel or engineering plastics, and can be provided with regular grout outlet holes according to actual conditions so as to improve the grouting effect.

The invention also provides a construction method of the anchor cable with the hole bottom yielding device, which comprises the following steps:

(1) drilling an anchor cable hole matched with the length of an anchor cable on the surface of the rock;

(2) firstly, putting a resin cartridge into the hole to the bottom of the hole, then inserting the pressure-yielding anchor head device, and stirring the resin cartridge to fully solidify the resin cartridge, the pressure-yielding anchor head device and the rock hole to form anchoring force;

(3) tensioning the steel strand to form a prestress, and screwing the locking piece when a preset locking force is reached; the tension force must be lower than the minimum allowable pressure of the pressure-yielding anchor head device;

(4) grouting the anchor cable holes as necessary: when the steel strand is stressed to generate yielding and sliding to a preset position, grouting into the anchor cable hole to enable the gap in the hole to be completely filled with inorganic slurry such as cement, and the like, so that full bonding anchoring is realized, and the installation of the anchor cable is completed;

or when the steel strand is not bonded with the isolation layer, the locking piece is immediately grouted to enable the hole to be filled with grouting bodies, and the installation is completed.

Compared with the prior art, the invention has the following beneficial effects:

1. compared with the existing anchor rod with a hole bottom yielding device, the anchor rod with the rigid rod body as the reinforcing rib has the advantages that the steel strand is adopted as the reinforcing rib of the anchor rod, the anchor rod has the characteristics of flexibility and bending, the operation space range is large, and the anchor rod has superiority to underground engineering chamber support with different sizes, such as the chamber operation height is 3m, and 9m long anchor rods are driven in during construction; rigid bolts are difficult.

2. The steel strand is used as a force bar, and compared with rigid rod bodies of solid and hollow rod bodies, the steel strand has the same diameter and steel consumption, so that the bearing capacity is large, and the cost is saved.

Drawings

FIG. 1 is a schematic structural view of example 1 of the present invention;

FIG. 2 is a first block diagram of an embodiment of the present invention;

FIG. 3 is a transverse cross-sectional view taken at the position A-A shown in FIG. 2 (the steel strands are laid using 7 strands of wires);

FIG. 4 is a transverse cross-sectional view taken at position B1-B1 shown in FIG. 2 (the steel strands are laid using 7 strands of wires);

FIG. 5 is a transverse cross-sectional view taken at the position A-A shown in FIG. 2 (the steel strands are laid using 19 strands of wires);

FIG. 6 is a transverse cross-sectional view taken at position B1-B1 shown in FIG. 2 (the steel strands are laid using 19 strands of steel wires);

FIG. 7 is a second block diagram of a yielding anchor head assembly in an embodiment of the present invention;

FIG. 8 is a transverse cross-sectional view taken at position B2-B2 shown in FIG. 7 (the steel strands are laid using 7 strands of wires);

FIG. 9 is a transverse cross-sectional view of the C-C position shown in FIG. 7 (the steel strands are laid using 7 strands of wires);

FIG. 10 is a longitudinal cross-sectional view of a tapered wedge tube in an embodiment of the present invention;

FIG. 11 is a schematic view of a retainer for the rear end of an anchor tube in accordance with an embodiment of the present invention;

FIG. 12 is a schematic structural view of example 2 of the present invention;

fig. 13 is a transverse cross-section at the position D-D shown in fig. 12 (the steel strands 2 are laid using 19 strands of wires).

Detailed Description

The invention will be described in further detail below with reference to the drawings and examples, which are intended to facilitate the understanding of the invention without limiting it in any way.

The anchor hole means a hole formed by drilling or the like in a ground layer to a predetermined diameter and depth to install an anchor, and therefore includes an anchor hole opening, an anchor hole bottom, and the like. "front" and "rear" are referenced with respect to the direction of the opening towards the bottom of the hole, and "rear" refers to the section of the anchor rod body or member towards or near the anchor rod opening; "front portion" means the portion of the bolt body or member that is towards or near the bottom of the bolt hole.

Example 1

As shown in fig. 1, an anchor cable with a hole bottom yielding device comprises a steel strand 2 and a supporting base plate 4, wherein an anchor pipe 10 is sleeved at the front part of the steel strand 2; the front end of the anchor pipe 10 is provided with a conical wedge pipe 11. The front end of the steel strand 2 passes through the anchor pipe 10 and then extends out of the front end of the anchor pipe 10; the conical wedge tube 11 is sleeved on the inner layer steel wire of the extending part of the steel strand 2 and forms extrusion fit with the outer layer steel wire, the inner layer steel wire and the inner cavity of the anchor tube of the steel strand.

The front end of the steel strand 2 extends out of the front end of the anchor pipe 10 to form a stirring head 25, the front part of the steel strand 2, the anchor pipe 10 and the conical wedge pipe 11 form a yielding anchor head device 1, and the rear part of the steel strand 2 is matched with the supporting base plate 4 through the locking piece 3. The front end of the yielding anchor head device 1 is provided with a stirring head 25, the yielding anchor head device 1 and the stirring head 25 are used as an anchoring section 200 for rapid bonding (such as resin cartridge anchoring agent), and the steel strand part at the rear end of the yielding anchor head device 1 is used as a grouting bonding section 100.

Specifically, the steel strand 2 is a flexible steel cable twisted by a plurality of high-strength steel wires and composed of an outer layer steel wire 21 and an inner layer steel wire 22, and as shown in fig. 3-4, the steel strand is 7 strands of steel strands which are an inner layer and an outer layer; as shown in fig. 5 to 6, the 19-strand steel strand is three-layered. According to the national standard GB/T5224-2014, the specification of 7 strands of steel strands is more, the nominal diameter phi is 9.5-phi 21.6, and the maximum force of the whole steel strand is 105 KN-530 KN; and the 19 strands of steel strands have relatively large diameter and large bearing capacity tonnage, taking (1+9+9) S as an example, the nominal diameter phi 17.8-phi 28.6 and the maximum force of the whole steel strand 368 KN-942 KN. The two can be adapted to different engineering occasions.

As shown in fig. 2, in order to provide a first structural view of the anchor head device 1, the anchor pipe 10 is a long straight pipe, two end surfaces are respectively a rear end surface 10a of the anchor pipe and a front end surface 10b of the anchor pipe, and the outer wall surface is a threaded surface or other regular concave-convex surface beneficial to resin anchoring. The conical wedge pipe 11 is placed in the front end surface 10b of the anchor pipe, and the big end of the conical wedge pipe faces forwards and the small end of the conical wedge pipe faces backwards; the front end of the steel strand 2 passes through the anchor pipe 10 concentric with the anchor pipe, and the conical wedge pipe 11 which is close to the front end surface 10b of the anchor pipe is sleeved on the inner layer steel wire 22 and is separated from the outer layer steel wire 21, and then passes out to form an outcrop so as to improve the stirring effect; the steel wires at the inner and outer layers of the outcrop have a certain length (such as 2-5 cm) and are used as a stirring head 25 of an anchoring agent.

A certain gap is formed between the anchor pipe 10 and the steel strand 2, and the gap can freely move, and is a transverse cross section of the yielding anchor head device 1 at the position A-A as shown in figure 3. As shown in fig. 4, in order to make the anchor head device 1 in a transverse cross section view from B1 to B1, the inner wall of the anchor pipe 10 is in force fit with the steel strand 2 and the conical wedge pipe 11. On the front end face 10b of the anchor pipe, the outer layer steel wire 21 of the steel strand 2 is in extrusion fit with the inner wall of the anchor pipe 10 by the wedge action principle of the conical wedge pipe 11, the tensile force is transmitted to the anchor pipe 10, and then the tensile force is transmitted to the rock stratum by the anchor pipe 10 and the bonding anchoring layer; on the contrary, the rock stratum stress is transmitted to the anchor pipe 10 through the bonding anchoring layer, and then transmitted to the steel strand 2 through the outer layer steel wire 21 and the conical wedge pipe 11 on the inner wall of the anchor pipe 10 to form a pulling force. The conical wedge 11 is mounted in a position that requires as full of the lumen of the anchor tube 10 as possible, preferably flush with the front anchor tube end face 10b (shown exposed for ease of illustration).

In order to ensure that the anchor pipe 10, the conical wedge pipe 11 and the steel strand 2 work cooperatively in the anchoring and stirring process, a positioning piece 12 is arranged at the position of the rear end surface 10a of the anchor pipe. As shown in fig. 2, the positioning member 12 is an anchor pipe 10 which is matched with the steel strand 2 by extrusion and has the function of enabling the steel strand not to be separated from the rotation of the steel strand but to slide longitudinally under a certain pulling force; as shown in fig. 11, a separate pin-type detent ring 15 is used as an alternative to the keeper.

As shown in fig. 10, which is a longitudinal sectional view of the tapered wedge tube 11, the tapered wedge tube 11 is a short steel tube, the inner hole of which is matched with the inner layer steel wire 22 of the steel strand 2, the taper of which is between 4 and 100, and the hardness of which is greater than that of the steel wire. The length of the anchor pipe 10 is determined according to the bearing capacity of the steel strand 2, the yielding slip amount and other factors, and is usually 0.5-1.5 m, and the material of the anchor pipe is alloy structural steel.

Another scheme of the yielding anchor head device 1 is as shown in fig. 7, and fig. 8 is a transverse cross-sectional view at the position B2-B2 shown in fig. 7 (the steel strands are laid by using 7 strands of steel wires); fig. 9 is a transverse cross-sectional view of the C-C position shown in fig. 7 (the steel strands are laid using 7 strands of wires). The difference with the first structure of letting press anchor head device 1 is:

1. the anchor tube 10 has a longitudinal slot 14 in the front anchor tube end 10b towards the rear anchor tube end 10a, and the number of the slots may be 1 or more (1 as shown in fig. 8). The length of the slot is not less than 20mm, but not more than 90% of the total length of the anchor tube 10. The front part of the anchor pipe is longitudinally grooved, so that the front end of the anchor pipe can be conveniently opened, the anchor pipe is suitable for different types of anchoring agent consolidation time (such as early cement anchoring agent and resin cartridges with different rapid and slow consolidation times), and meanwhile, the mechanical matching of the outer wall of the anchor pipe and the wall of the rock hole has the effect similar to that of an Expansion Shell anchoring head (Expansion Shell) in the prior art.

2. The structure of the mixing head 25 is that the inner and outer layer steel wires of the steel strand 2 are exposed after passing through the anchor pipe 10 and the conical wedge pipe 11, and the diffused steel wires are bundled by the front end fastener 13 to form a bullet-shaped mixing head, as shown in fig. 7.

The device of the invention is arranged in a stratum rock hole (not shown), is fixed on a supporting surface through a locking piece 3 and a supporting cushion plate 4, and forms a certain prestress to actively support a stratum through tensioning the steel strand 2, when stratum stress is transmitted to the steel strand 2 and exceeds a certain yielding value, the steel strand 2 drives the conical wedge tube 11 and the outer layer steel wire 22 to frictionally slide along the inner wall of the anchor tube in the anchor tube 10, and the steel strand 2 extends outwards to release stratum energy. Meanwhile, the conventional cement grouting process is adopted to perform grouting on the grouting bonding section 100 to form full bonding.

In addition, the steel strand 2 can adopt a bonded steel strand and a non-bonded steel strand according to different conditions before and after the grouting process and the yielding slip process of the anchor cable. When the requirement on corrosion resistance is high, epoxy coating steel strands or slow bonding steel strands are preferably adopted.

Example 2

Fig. 12 is a schematic structural view of a second embodiment of the present invention, which is used for supporting with high durability requirement. The differences from example 1 are described below:

the grouting isolation sleeve 6 is further included, and the locking piece 5 with the anchoring-grouting integrated function is matched with the bearing backing plate 4. The front end of the steel strand 2 is connected with the yielding anchor head device 1, the rear end of the steel strand is matched with the locking piece 5 and the supporting base plate 4, and a grouting isolation sleeve 6 penetrates through the middle of the steel strand. The front end of the grouting isolation sleeve 6 extends to and near the rear end surface 10a of the anchor pipe, and the rear end thereof is butted with the connecting section 52 of the locking piece 5.

The front end of the yielding anchor head device 1 is provided with a stirring head 25, the yielding anchor head device 1 and the stirring head 25 are used as an anchoring section 200 for rapid bonding (such as resin cartridge anchoring agent), and the steel strand part at the rear end of the yielding anchor head device 1 is used as a grouting bonding section 100.

The locking piece 5 comprises a locking function section 50, a pad and grouting function section 51 and a connecting section 52 which is in plug fit with the grouting isolation sleeve 6. The locking piece 5 further comprises a lateral grouting hole 53 and a longitudinal inner hole, the inner cavity of the lateral grouting hole 53 is used for penetrating the steel strand 2 and locking, and an inner and outer communicating channel is formed with the grouting hole 53, the inner cavity 500 of the grouting isolation sleeve 6 and the grout outlet hole 61 on the sleeve and is used for grouting and bonding the grouting bonding section 100. The locking function section 50, the shoe and the grouting function section 51 may also be separated into two separate parts.

The grouting isolation sleeve 6 is a corrugated pipe, the material of the grouting isolation sleeve can be stainless steel or engineering plastics, and a regular grout outlet 61 can be formed in the pipe wall according to actual conditions so as to improve the grouting effect, and is shown in fig. 13.

After the yielding anchor head device 1 is installed, the front end part can be quickly anchored with a rock body to form an anchoring section and used as tensioning prestress, the anchoring section is locked by the locking piece 5 with the anchoring-grouting integrated combination function, and meanwhile, when the yielding anchor head device 1 is pulled to exceed a rated yielding pressure value, the steel strand 2 slides and extends in the yielding anchor head device 10 to enable the yielding anchor head device 10 to be anchored with the rock body integrally and not to move, so that a constant-resistance yielding function is formed.

After yielding, the lateral grouting holes 53 of the locking piece 5 are grouted inwards to bond and grout the anchor cable in the whole length, and the grouting isolation sleeve 6 is made of engineering plastics or stainless steel corrugated pipes, can isolate water and gas from entering and has double anticorrosion functions and permanent working capacity. In order to achieve the anti-corrosion performance, the steel strand 2 can also adopt anti-corrosion technologies such as epoxy resin coatings and the like, so that the durability is further improved.

The invention discloses a construction method of an anchor cable with a hole bottom yielding device, which comprises the following steps:

The embodiments described above are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions and equivalents made within the scope of the principles of the present invention should be included in the scope of the present invention.

Claims

1. An anchor cable with a hole bottom yielding device comprises a steel strand and a supporting base plate, and is characterized in that an anchor pipe is sleeved at the front part of the steel strand, and the steel strand penetrates through the anchor pipe and then is scattered into a plurality of steel wires; wherein, the inner layer steel wire is sleeved with the conical wedge pipe, and the inner layer steel wire, the conical wedge pipe, the outer layer steel wire and the inner cavity of the anchor pipe form extrusion fit; the rear part of the steel strand is matched with the supporting base plate through a locking piece;

the locking piece comprises a locking function section, a cushion seat, a grouting function section and a connecting section; the pad seat and the grouting functional section are provided with lateral grouting holes, and the inner cavity of the locking piece is used for penetrating and locking a steel strand;

the middle part of the steel strand is sleeved with a grouting isolation sleeve; the front end of the grouting isolation sleeve is close to the rear end face of the anchor pipe, and the rear end of the grouting isolation sleeve is in butt joint with the connecting section of the locking piece; the lateral grouting holes and the inner cavity of the grouting isolation sleeve form a channel which is communicated with the inside and the outside.

2. The anchor cable with a hole bottom pressure relief device as claimed in claim 1, wherein the anchor pipe is a round straight pipe, and the outer surface is a threaded surface or other regular concave-convex surface.

3. The anchor cable with the bottom yielding device as claimed in claim 1, wherein a positioning member is provided at the rear end of the anchor pipe, and the steel strand is dispersed into a plurality of steel wires after passing through the positioning member and the anchor pipe; the locating piece is formed by extruding the rear end of the anchor pipe, or an independent pin key type braking ring is adopted.

4. The anchor rope with bottom pressure relief device as claimed in claim 1, wherein the front portion of said anchor pipe is provided with at least one longitudinal slot, the length of said slot is not less than 20mm and not more than 90% of the total length of said anchor pipe.

5. The anchor cable with the bottom pressure relief device as claimed in claim 1, wherein the steel strand is extruded by the conical wedge tube to form a spreading stirring head after passing through the anchor tube, and the spreading steel wire has a protruding end at the front end of the anchor tube.

6. The anchor rope with hole bottom pressure relief device as claimed in claim 1, wherein said steel strand is passed through the anchor tube and then gathered into a bundle by a front fastener to form a bullet-shaped mixing head.

7. The anchor cable with hole bottom pressure relief device as claimed in claim 1, wherein said steel strand is 7 strands or 19 strands; when 7 strands of steel wires are adopted, the inner layer steel wire and the outer layer steel wire are both one layer; when 19 strands of steel wires are adopted, the inner layer steel wires are two layers, and the outer layer steel wires are one layer.

8. The anchor cable with hole bottom pressure relief device as claimed in claim 1, wherein said conical wedge tube is fully inserted into the inner cavity of the anchor tube when installed.

9. The anchor cable with a bottom pressure relief device as claimed in claim 1, wherein said grouting isolation sleeve is provided with a plurality of grout outlet holes; the slurry outlet hole, the lateral grouting hole and the inner cavity of the grouting isolation sleeve form a channel which is communicated with the inside and the outside.

10. The anchor cable with the bottom pressure relief device according to claim 1, wherein the locking functional section, the pad seat and the grouting functional section are of an integral structure or of two separate structures.

11. The anchor cable with hole bottom pressure relief device as claimed in claim 1, wherein said grouting isolation sleeve is a corrugated tube made of stainless steel or engineering plastic.

12. The construction method of the anchor cable with the hole bottom yielding device as claimed in claim 1 to 11, which comprises the following steps:

or when the steel strand is not bonded with the isolation layer, grouting is carried out immediately after the locking piece to enable the hole to be filled with grouting body, and the installation is completed.