Pressure relief type segmented rotary jet grouting anchor rod and construction method

Abstract

The invention provides a pressure relief type segmented rotary jet grouting anchor rod and a construction method, and belongs to the field of ground stress measurement and surrounding rock supporting design research, the pressure relief type segmented rotary jet grouting anchor rod comprises a rotary jet drilling rod, a pressure relief drilling rod, an expandable hole packer and a detachable drilling bit, the rotary jet drilling rod comprises a rotary jet end, a rotary jet rod body and a rotary jet tail, the pressure relief drill rod comprises a pressure relief end part, a pressure relief rod body and a pressure relief tail part; the pressure relief tail part is spirally connected with the detachable drill bit; the expandable hole packer is of a sleeve type structure, and the expandable hole packer is arranged on the outer side of the spiral connecting position of the pressure relief end and the rotary spraying tail in a sleeving mode. According to the method, the surrounding rock at the deep position of the drill hole and the hole opening can be strengthened in a segmented mode through the pressure relief and reinforcement combined method, the internal crack condition of the surrounding rock is improved, extrusion stress between the surrounding rock is reduced, and disturbance is avoided; and meanwhile, surrounding rock at the hole can be reinforced, and safety accidents caused by falling are prevented.

Description

Technical Field

[0001] The invention relates to the research field of ground stress measurement and surrounding rock support design, and in particular to a pressure-relieving segmented rotary jet grouting anchor rod and a construction method. Background Art

[0002] Geostress testing is a technology for measuring the internal stress of rock mass in its natural state, which is of great significance for engineering rock mass stability analysis and engineering design. Under the action of various dynamic movements, the crust will produce various stress fields, which will put the crustal material under its comprehensive action and produce internal stress effects. This stress is geostress. From the perspective of rock engineering, rock mass geostress mainly comes from geological tectonic movement and rock mass deadweight. Geostress testing has a wide range of applications in engineering construction, earthquake research, resource development and other fields. Accurately measuring geostress is of great significance for evaluating the stability of underground engineering, preventing geological disasters, and guiding resource exploration and development.

[0003] The development of geostress testing technology originated from early mining engineering construction, and the earliest in-situ geostress measurement began in the 1930s. With the birth and development of disciplines such as rock mechanics, numerical analysis, and engineering testing technology, geostress measurement theory and testing technology have also been innovated and developed. Common geostress testing methods include stress recovery method, stress relief method, and hydraulic fracturing method. Stress recovery method, also known as stress compensation method, is the earliest geostress testing technology used; the principle of stress relief method is that after the rock block is taken out of the rock mass with a certain stress environment, the rock undergoes elastic deformation, and the elastic deformation of the rock block after contact is measured. The elastic modulus is determined by rock mechanics experiments, and the stress magnitude and direction in the rock mass before relief can be calculated by Hooke's law; the basic assumption of hydraulic fracturing method is that the rock is isotropic, homogeneous medium, continuum, linear elastic body, and in addition, it is assumed that the drilling direction is a principal stress direction, thereby converting the problem into a problem of measuring the other two principal stresses in the plane. Regardless of the test method, during the ground stress test, due to the disturbance of the surrounding rocks, some places with higher ground stress may cause the surrounding rocks to fall off due to mutual compression between the surrounding rocks, which poses certain safety hazards to the test personnel. Summary of the invention

[0004] The purpose of the present invention is to provide a pressure-relief type segmented rotary jet grouting anchor rod and a construction method, which can strengthen the surrounding rock in the deep hole and at the hole entrance in segments by combining pressure relief and reinforcement, improve the internal cracks of the surrounding rock, reduce the compressive stress between the surrounding rocks, and avoid disturbance; at the same time, the surrounding rock at the hole entrance can be reinforced to prevent safety accidents caused by falling off.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first aspect, a pressure-relief type segmented rotary jet grouting anchor rod is characterized in that it includes a rotary jet drill rod, a pressure-relief drill rod, an expandable hole sealer and a detachable drill bit, the rotary jet drill rod includes a rotary jet end, a rotary jet rod body and a rotary jet tail, the rotary jet end is a threaded column, the rotary jet tail is a threaded cone, the rotary jet rod body is a hollow structure, a rotary jet pipe is arranged inside the rotary jet rod body, a rotary jet grouting pipe is arranged inside the rotary jet pipe, and a rotary jet port is arranged on the rotary jet pipe.

[0007] The pressure relief drill rod includes a pressure relief end, a pressure relief rod body and a pressure relief tail. The pressure relief end is an embedded threaded structure. A small hole is provided inside the pressure relief end. A slurry stopper is provided at the small hole. The pressure relief end is spirally spliced ​​with the rotary jet tail. The pressure relief rod body is a hollow structure. The pressure relief tail is a threaded column. The pressure relief tail is spirally connected to a detachable drill bit.

[0008] The expandable hole sealer is a sleeve-type structure, and the expandable hole sealer is sleeved on the outside of the spiral connection between the pressure relief end and the rotary spray tail.

[0009] Furthermore, the expandable hole sealer includes a fixed metal inner wall, an expandable outer wall and an elastic airbag, the fixed metal inner wall is fitted with the spiral connection between the pressure relief end and the rotary spray tail, the expandable outer wall is arranged on the outside of the expandable hole sealer, and the elastic airbag is arranged inside the expandable hole sealer.

[0010] A triangular bracket is arranged outside the expandable outer wall, the diameter of the fixed metal inner wall is the same as the diameter of the rotary jet rod body, and the diameter of the expandable outer wall is smaller than the diameter of the drill hole.

[0011] Furthermore, a pressure relief grouting pipe is provided inside the rotary jet drill rod, and the pressure relief grouting pipe enters into the small hole inside the pressure relief end through the rotary jet rod body, and the grouting plug is opened by the insertion of the pressure relief grouting pipe, and the grouting plug is automatically closed after the pressure relief grouting pipe is withdrawn. The pressure relief grouting pipe can enter into the pressure relief rod body through the interface of the pressure relief end, the diameter of the pressure relief grouting pipe is the same as the diameter of the small hole inside the pressure relief end, and the size of the grouting plug is the same as the size of the interface.

[0012] Furthermore, the elastic air bag inside the expandable hole sealer is connected to a pressure pump through a pressurized tube, and the pressure pump is arranged outside the borehole.

[0013] Furthermore, a gasket is sleeved on the outer side of the rotary spray end, the gasket is a metal thin-walled circular ring, and the gasket is larger than the drilled hole; and a nut is sleeved on the rotary spray end.

[0014] Furthermore, a pressure relief port is provided inside the pressure relief tail portion.

[0015] In a second aspect, a construction method of a pressure-relief segmented rotary jet grouting anchor bolt is characterized by comprising the following steps:

[0016] 1) Lay a layer of metal mesh outside the surrounding rock to be supported. If the surrounding rock becomes loose, it can be reinforced with shotcrete.

[0017] 2) Install anchor rods. Use pressure-relief segmented jet grouting anchor rods at preset locations. After the pressure-relief drill rod is buried, insert the jet grouting pipe into the jet grouting pipeline.

[0018] 3) The detachable drill bit works, the pressure-relief segmented jet grouting anchor rod continues to go deeper, and the high-pressure cement slurry is injected into the jet grouting pipe through the jet grouting pipe, and is evenly sprayed on the hole wall surface and the cracks in the hole wall from the jet nozzle.

[0019] 4) When the pressure-relief segmented jet-jet anchor is driven into the preset depth, the jet-jet grouting pipe is withdrawn, and the elastic airbag in the expandable hole sealer is pressurized by a pressure pump to expand it and seal the borehole. The triangular bracket is embedded in the hole wall as the elastic airbag expands.

[0020] 5) Remove the pressure pump and pressurized pipe, and install the gasket and nut.

[0021] 6) Insert the pressure relief grouting pipe into the pressure relief drill pipe, and inject the pressure relief material into the pressure relief rod body under high pressure. Under the action of pressure, the pressure relief material is injected into the deep hole wall and surrounding rock cracks from the small holes inside the pressure relief end.

[0022] Advantages of the present invention:

[0023] The present invention uses a combination of deep pressure relief and shallow reinforcement to reinforce the surrounding rock. In the depth of the surrounding rock, due to the high ground stress between the rock masses, it is easy to cause large pieces of shallow surrounding rock to fall off on the basis of the original cracks. Pressure relief can better improve this high ground stress situation and fill the original cracks. The expandable sealer can make the pressure relief material diffuse better into the depth of the cracks, and can achieve pressure relief and consolidation of a point within a range; at the borehole mouth, laying a metal mesh can prevent the surrounding rock from falling off, and through rotary grouting, the outermost surrounding rock can be reinforced, ensuring the safety of workers and experimental equipment during construction operations (such as drilling or blasting). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a pressure-relief type segmented rotary jet grouting anchor rod in the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the rotary jet drilling rod in the present invention;

[0026] Figure 3 It is a structural schematic diagram of the pressure relief drill rod in the present invention;

[0027] Figure 4 A half-section schematic diagram of a pressure relief anchor rod in the present invention;

[0028] Figure 5 This is a schematic diagram of the installation of a pressure relief anchor rod in an embodiment of the present invention;

[0029] Figure 6 It is a schematic diagram of the structure of the expandable hole sealer in the present invention;

[0030] In the figure: 1. Jet-jet drill rod; 2. Pressure relief drill rod; 3. Expandable hole sealer; 4. Removable drill bit; 5. Nut; 6. Gasket; 7. Jet-jet pipe; 8. Jet-jet outlet; 9. Triangle bracket; 10. Pressure pump; 11. Pressurizing pipe; 12. Interface; 13. Pressure relief grouting pipe; 14. Pressure relief outlet; 15. Jet-jet end; 16. Jet-jet tail; 17. Pressure relief end; 18. Grouting stopper; 19. Pressure relief tail; 20. Fixed metal inner wall; 21. Expandable outer wall; 22. Elastic air bag; 23. Drilling; 24. Jet-jet grouting pipe. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0032] like Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, a pressure-relief type segmented rotary jet grouting anchor rod comprises a rotary jet drill rod 1, a pressure-relief drill rod 2, an expandable hole sealer 3 and a detachable drill bit 4, wherein the rotary jet drill rod 1 comprises a rotary jet end 15, a rotary jet rod body and a rotary jet tail 16, wherein the rotary jet end 15 is a threaded column, the rotary jet tail 16 is a threaded frustum, the rotary jet rod body is a hollow structure, a rotary jet pipe 7 is arranged inside the rotary jet rod body, a rotary jet grouting pipe 24 is arranged inside the rotary jet pipe 7, and a rotary jet port 8 is arranged on the rotary jet pipe 7.

[0033] The pressure relief drill rod 2 includes a pressure relief end 17, a pressure relief rod body and a pressure relief tail 19. The pressure relief end 17 is an embedded threaded structure. A small hole is provided inside the pressure relief end 17. A slurry stopper 18 is provided at the small hole. The pressure relief end 17 is spirally spliced ​​with the rotary jet tail 16. The pressure relief rod body is a hollow structure. The pressure relief tail 19 is a threaded column. The pressure relief tail 19 is spirally connected to the detachable drill bit 4.

[0034] The expandable hole sealer 3 is a sleeve-type structure, and the expandable hole sealer 3 is sleeved on the outside of the spiral connection between the pressure relief end 17 and the rotary spray tail 16 .

[0035] As a preferred embodiment of the present invention, Figure 4 and Figure 6 As shown, the expandable hole sealer 3 includes a fixed metal inner wall 20, an expandable outer wall 21 and an elastic airbag 22. The fixed metal inner wall 20 is fitted with the spiral connection between the pressure relief end 17 and the rotary spray tail 16. The expandable outer wall 21 is arranged on the outside of the expandable hole sealer 3, and the elastic airbag 22 is arranged inside the expandable hole sealer 3.

[0036] A triangular bracket 9 is disposed outside the expandable outer wall 21 . The diameter of the fixed metal inner wall 20 is the same as the diameter of the rotary jet rod body. The diameter of the expandable outer wall 21 is smaller than the diameter of the drill hole 23 .

[0037] As a preferred embodiment of the present invention, Figure 1 As shown, a pressure relief grouting pipe 13 is arranged inside the rotary jet drill rod 1, and the pressure relief grouting pipe 13 enters into the small hole inside the pressure relief end 17 through the rotary jet rod body, and the grouting plug 18 is opened by the insertion of the pressure relief grouting pipe 13. After the pressure relief grouting pipe 13 is withdrawn, the grouting plug 18 is automatically closed, and the pressure relief grouting pipe 13 can enter into the pressure relief rod body through the interface 12 of the pressure relief end 17. The diameter of the pressure relief grouting pipe 13 is the same as the diameter of the small hole inside the pressure relief end 17, and the size of the grouting plug 18 is the same as the size of the interface 12.

[0038] As a preferred embodiment of the present invention, Figure 5 As shown, the elastic airbag 22 inside the expandable hole sealer 3 is connected to the pressure pump 10 through the pressurized tube 11. The pressure pump 10 is arranged outside the borehole 23. The pressure pump 10 continuously applies pressure, and the expandable outer wall 21 is expanded to tightly wrap the borehole 23. The triangular bracket 9 is then expanded and embedded in the inner wall of the borehole 23, thereby improving the stability of the anchor rod.

[0039] As a preferred embodiment of the present invention, a gasket 6 is sleeved on the outer side of the rotary spray end 15 . The gasket 6 is a metal thin-walled circular ring. The gasket 6 is larger than the drilled hole 23 . The rotary spray end 15 is sleeved with a nut 5 .

[0040] As a preferred embodiment of the present invention, a pressure relief port 14 is provided inside the pressure relief tail portion 19 .

[0041] Based on the above-mentioned pressure relief type segmented rotary jet grouting anchor rod, the present invention also proposes a construction method of the pressure relief type segmented rotary jet grouting anchor rod, comprising the following steps:

[0042] 1) Lay a layer of metal mesh outside the surrounding rock to be supported. If the surrounding rock becomes loose, it can be reinforced with shotcrete.

[0043] 2) Install the anchor rod, assemble the jet grouting drill rod 1, the pressure relief drill rod 2 and the detachable drill bit 4, and bond the expandable hole sealer 3 together with an adhesive material, use the pressure relief segmented jet grouting anchor rod at the preset point, and when the pressure relief drill rod 2 is buried, insert the jet grouting pipe 24 into the jet grouting pipeline 7.

[0044] 3) The detachable drill bit 4 works, the pressure-relief segmented jet anchor rod continues to go deeper, and the high-pressure cement slurry is injected into the jet pipe 7 through the jet grouting pipe 24, and is evenly sprayed on the hole wall surface and the hole wall cracks from the jet nozzle 8, so that the surrounding rock around the borehole 23 is reinforced.

[0045] 4) After the pressure-relief segmented jet-jet anchor rod is driven into the preset depth, the jet-jet grouting pipe 24 is withdrawn, and the elastic airbag 22 in the expandable hole sealer 3 is pressurized by the pressure pump 10 so that it expands and seals the borehole 23, and the triangular bracket 9 is embedded in the hole wall as the elastic airbag 22 expands.

[0046] 5) Remove the pressure pump 10 and the pressure pipe 11, and install the gasket 6 and the nut 5 to fasten the anchor rod inside the borehole 23.

[0047] 6) Insert the pressure relief grouting pipe 13 into the pressure relief drill rod 2, and inject the pressure relief material (such as foam concrete) into the pressure relief rod body under high pressure. Under the action of pressure, the pressure relief material is injected into the deep hole wall and the surrounding rock cracks from the small holes inside the pressure relief end 17.

[0048] The working principle and specific operation steps of the present invention are as follows:

[0049] In the flat tunnel that has been excavated on the mountainside, since the area is located at a high altitude and surrounded by mountains, the surrounding rocks inside the nearby mountains are under high ground stress. If relevant tests are to be carried out at a certain excavation surface in the flat tunnel, the surrounding rock stress in the surrounding mountains is too large, and the mutual disturbance between the rock masses is too large, causing the edge of the excavation surface to loosen or even fall, and in more serious cases, it may cause the collapse of the flat tunnel. Therefore, the surrounding rock of the required excavation surface needs to be reinforced before the test.

[0050] First, a layer of metal mesh is laid on the surface of the surrounding rock to be reinforced to prevent the loosening or falling of the edge surrounding rock and the safety accidents of personnel and equipment. The jet grouting drill rod 1 and the pressure relief drill rod 2 are spirally spliced, and the jet grouting tail 16 and the pressure relief end 17 are embedded spiral structures. After the splicing is completed, the expandable hole sealer 3 is sleeved on the outer end of the splicing of the two drill rods with an adhesive; after the anchor rod is assembled, the rotary spray end 15 is fixed on the drilling rig and the detachable drill bit 4 is aligned with the preset reinforcement point; the drilling rig is started, and the detachable drill bit 4 begins to be buried. When the pressure relief drill rod 2 is completely buried, the rotary spray grouting pipe is inserted into the rotary spraying pipeline 7. When the drilling depth reaches the rotary spraying port 8, high-pressure cement slurry is injected through the rotary spraying pipeline 7. The cement slurry is sprayed out from the rotary spraying port 8 and evenly sprayed on the surrounding rock hole wall and the cracks in the hole wall. After the cement slurry solidifies, it helps to improve the firmness of the shallow surrounding rock and fill the cracks to a certain extent, which can effectively improve the stability of the surrounding surrounding rock; as the detachable drill bit 4 reaches the preset drilling depth, the drilling rig is turned off and the rotary spraying grouting pipe is removed. At this point, the work of rotary spraying anchoring the shallow surrounding rock is completed.

[0051] Secondly, the staff operates the pressure pump 10 outside the borehole 23 to inflate and pressurize the elastic airbag 22 in the expandable hole sealer 3 through the pressure tube 11. The elastic airbag 22 has a maximum limit to bear. When this limit is reached, the elastic airbag 22 swells and drives the expandable outer wall 21 to expand, tightly sealing the borehole 23. The triangular bracket 9 located outside the expandable hole sealer 3 will be ejected and embedded in the surrounding rock of the hole wall as the expandable outer wall 21 expands. After the hole is sealed, the pressure pump 10 and the pressure tube 11 are removed, and the hole sealing process is completed. An expandable hole sealer 3 with a triangular bracket 9 is added to the outside of the anchor rod. The triangular bracket 9 can ensure the stability of the anchor rod in the borehole. The expanded expandable hole sealer 3 can seal the borehole tightly, so that the pressure relief section is a closed environment. When grouting, the pressure relief material can be injected into the deep cracks of the deep hole wall of the surrounding rock by pressure, so as to achieve point-to-surface, and spread from one point to a reinforced surface. Next, the anchoring process enters the pressure relief section.

[0052] After the hole is sealed, a gasket 6 is put on the rotary grouting end 15. The gasket 6 is a metal thin-walled ring. The gasket is larger than the size of the drill hole. A nut 5 is put on the rotary grouting end 15 and screwed until it is firmly fixed at the drill hole 23. The pressure relief grouting pipe 13 is inserted. The pressure relief grouting pipe 13 passes through the rotary grouting rod body of the rotary grouting drill rod 1 and enters the pressure relief rod body of the pressure relief drill rod 2 from the interface between the rotary grouting tail 16 and the pressure relief end 17. There is a contact grouting plug 18 at the pressure relief end 17. The size of the grouting plug 18 is the same as that of the interface 12. The grouting plug 18 adopts a spring connection. When the pressure relief grouting pipe 13 passes through the interface 12, the grouting stop plug 18 opens inward, and the pressure relief material is injected into the pressure relief rod body under high pressure by the pressure relief grouting pipe 13. At the connection between the pressure relief tail 19 and the detachable drill bit 4, there are two pressure relief ports 14 for the pressure relief material to enter the deep hole wall and the surrounding cracks from the pressure relief rod body. When the internal grouting is completed, the pressure in the enclosed space formed by the expandable hole sealer 3 in the pressure relief section increases, and it is difficult to continue grouting at this time, so it is stopped, the pressure relief grouting pipe 13 is removed, and the grouting stop plug 18 is closed accordingly, and the work of the pressure relief section is completed. After the pressure relief material enters the deep hole wall and surrounding cracks and solidifies, it can fill the cracks on the one hand and reduce the ground stress of the deep surrounding rock on the other hand. The presence of the pressure relief material can effectively reduce the disturbance between adjacent surrounding rocks and indirectly reduce the squeezing effect of the deep surrounding rock on the shallow surrounding rock. The shallow surrounding rock is reinforced by high-pressure cement slurry. This method of shallow reinforcement and deep pressure relief makes the surrounding rock in a large spatial range reinforced.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the above embodiments or replace some of the technical features by equivalents. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A pressure relief segmented rotary jet grouting anchor, characterized in that: The invention comprises a jet grouting drill rod (1), a pressure relief drill rod (2), an expandable hole sealer (3) and a detachable drill bit (4); the jet grouting drill rod (1) comprises a jet grouting end (15), a jet grouting rod body and a jet grouting tail (16); the jet grouting end (15) is in the shape of a threaded column; the jet grouting tail (16) is in the shape of a threaded truncated cone; the jet grouting rod body is a hollow structure; a jet grouting pipe (7) is arranged inside the jet grouting rod body; a jet grouting pipe (24) is arranged inside the jet grouting pipe (7); and a jet grouting port (8) is arranged on the jet grouting pipe (7); The pressure relief drill rod (2) comprises a pressure relief end portion (17), a pressure relief rod body and a pressure relief tail portion (19); the pressure relief end portion (17) is an embedded threaded structure; a small hole is provided inside the pressure relief end portion (17); a slurry stopper (18) is provided at the small hole; the pressure relief end portion (17) is spirally spliced ​​with the rotary jet tail portion (16); the pressure relief rod body is a hollow structure; the pressure relief tail portion (19) is a threaded columnar shape; and the pressure relief tail portion (19) is spirally connected to the detachable drill bit (4); The expandable hole sealer (3) is a sleeve-type structure, and the expandable hole sealer (3) is sleeved on the outside of the spiral connection between the pressure relief end (17) and the rotary spray tail (16).

2. A pressure relief segmented jet grouting anchor according to claim 1, characterized in that: The expandable hole sealer (3) comprises a fixed metal inner wall (20), an expandable outer wall (21) and an elastic airbag (22); the fixed metal inner wall (20) is fitted to the spiral connection between the pressure relief end (17) and the rotary jet tail (16); the expandable outer wall (21) is arranged on the outside of the expandable hole sealer (3); and the elastic airbag (22) is arranged inside the expandable hole sealer (3); A triangular bracket (9) is arranged outside the expandable outer wall (21), the diameter of the fixed metal inner wall (20) is the same as the diameter of the rotary jet rod body, and the diameter of the expandable outer wall (21) is smaller than the diameter of the drill hole (23).

3. A pressure relief segmented jet grouting anchor according to claim 2, characterized in that: A pressure relief grouting pipe (13) is arranged inside the rotary jet drilling rod (1). The pressure relief grouting pipe (13) enters into the small hole inside the pressure relief end (17) through the rotary jet rod body. The grouting stopper (18) is opened by inserting the pressure relief grouting pipe (13). After the pressure relief grouting pipe (13) is withdrawn, the grouting stopper (18) is automatically closed. The pressure relief grouting pipe (13) can enter into the pressure relief rod body through the interface (12) of the pressure relief end (17). The diameter of the pressure relief grouting pipe (13) is the same as the diameter of the small hole inside the pressure relief end (17). The size of the grouting stopper (18) is the same as the size of the interface (12).

4. A pressure-relief segmented jet grouting anchor according to claim 3, characterized in that: The elastic air bag (22) inside the expandable hole sealer (3) is connected to a pressure pump (10) via a pressure pipe (11), and the pressure pump (10) is arranged outside the borehole (23).

5. A pressure relief segmented jet grouting anchor according to claim 4, characterized in that: A gasket (6) is sleeved on the outer side of the rotary spray end (15); the gasket (6) is a metal thin-walled circular ring, and the gasket (6) is larger than the drilled hole (23); and a nut (5) is sleeved on the rotary spray end (15).

6. A pressure relief segmented jet grouting anchor according to claim 5, characterized in that: A pressure relief port (14) is provided inside the pressure relief tail portion (19).

7. A construction method for a pressure-relief segmented jet grouting anchor bolt, characterized in that: The following steps are involved: 1) Lay a layer of metal mesh outside the surrounding rock to be supported. If the surrounding rock is loose, it can be reinforced with sprayed concrete; 2) Installing anchor rods, using pressure relief segmented jet grouting anchor rods at preset points, and after the pressure relief drill rod (2) is buried, inserting the jet grouting pipe (24) into the jet grouting pipeline (7); 3) The detachable drill bit (4) works, the pressure-relief segmented jet grouting anchor rod continues to go deeper, and the high-pressure cement slurry is injected into the jet grouting pipe (7) through the jet grouting pipe (24), and is evenly sprayed on the hole wall surface and the cracks in the hole wall from the jet nozzle (8); 4) After the pressure-relief segmented jet-jet anchor rod is driven into a preset depth, the jet-jet grouting pipe (24) is withdrawn, and the elastic airbag (22) in the expandable hole sealer (3) is pressurized by the pressure pump (10) so that the elastic airbag (22) expands and seals the borehole (23), and the triangular bracket (9) is embedded in the hole wall as the elastic airbag (22) expands; 5) Remove the pressure pump (10) and the pressure pipe (11), and install the gasket (6) and the nut (5); 6) Insert the pressure relief grouting pipe (13) into the pressure relief drill rod (2), and inject the pressure relief material into the pressure relief rod body under high pressure. Under the action of pressure, the pressure relief material is injected into the deep hole wall and the surrounding rock cracks from the small hole inside the pressure relief end (17).

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