A fixed-point grouting drill tool and method

Abstract

The present invention provides a fixed-point grouting drill tool and method. The drill tool includes a reduced-diameter joint, a safety joint, a check valve, a grout stopper, a pressure-limiting valve, and a guide head that are connected in sequence from the rear to the front. The method includes determining the grouting depth and setting position, lowering a drillable grouting drill tool, setting the grout stopper, grouting under pressure, lifting and flushing the drill pipe, and waiting for the grout to set and cleaning the hole, which are six steps. The present invention uses a grout stopper to achieve fixed-point setting, and a pressure-limiting valve to control the flow direction of the grouting slurry. The drill tool cooperates with a high-pressure sealed drill pipe, can achieve fixed-point grouting in the long borehole fault zone (broken zone) formation, avoid waste caused by full-hole-section grouting, improve the drilling construction efficiency, and reduce the drilling construction cost.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine drilling, relates to fixed-point grouting, and particularly relates to a fixed-point grouting drill tool and method. Background Art

[0002] With the development of coal mine drilling technology, the supporting process technology schemes for conventional borehole construction have become increasingly mature, and the requirements for different strata and different uses have been basically solved. However, when the borehole encounters a large-drop fault zone (including fracture zone) during drilling, even if the directional branch opening method is used, it is impossible to completely avoid the borehole trajectory, resulting in difficult drilling. In severe cases, the borehole may even be scrapped. Grouting and strengthening the formation is a common and very effective solution. At present, the borehole grouting in the coal mine fault zone (including fracture zone) adopts the form of setting the hole mouth plug. When implementing full-hole grouting, since the previously constructed intact hole section will also be solidified by the grouting slurry, it is necessary to re-drill the hole, which seriously affects the borehole construction efficiency and increases the construction cost.

[0003] The key to implementing fixed-point grouting for boreholes in the coal mine fault zone (including fracture zone) is to isolate the fractured hole section that needs to be grouted from the intact hole section that does not need to be grouted. In theory, the packers commonly used in the oil drilling field can achieve this goal. However, during actual construction, if the packer is directly set on the open-hole wall, the outer rubber cylinder of the packer is prone to strength failure after repeated use in the open-hole wall. In addition, the structure of the packer is relatively complex and not suitable for direct application in coal mine underground grouting construction.

[0004] The key to implementing fixed-point grouting for long boreholes in coal mines is to accurately control the setting time of the grouting slurry and the top drive liquid volume. Theoretically, a large top drive liquid volume is likely to break through the formation and cause slurry leakage, while a small top drive liquid volume is likely to cause the grouting slurry to remain in the grouting drill pipe, resulting in the solidification of the grouting slurry in the grouting drill pipe during the setting process and causing the grouting drill pipe to be scrapped. However, during actual construction, if it is necessary to accurately control the setting time of the grouting slurry and the top drive liquid volume, the success rate is low and the grouting process will be cumbersome. Summary of the Invention

[0005] Aiming at the defects and deficiencies existing in the prior art, the purpose of the present invention is to provide a fixed-point grouting drill tool and method to solve the technical problem of low construction efficiency of fixed-point grouting for boreholes in the coal mine fault zone (including fracture zone) in the prior art.

[0006] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0007] A fixed-point grouting drill tool includes a reduced-diameter joint, a safety joint, a check valve, a grout stopper, a pressure limiting valve, and a guide head, which are connected in sequence from back to front.

[0008] The described grout stopper includes an expandable outer cylinder, and a central tube body is fixedly sleeved inside the expandable outer cylinder. The rear end of the central tube body is flush with the rear end of the expandable outer cylinder, and the front end of the central tube body extends out of the front end of the expandable outer cylinder. A check valve is fixedly installed inside the rear part of the central tube body, and the front part of the central tube body is fixedly installed inside a pressure limiting valve. The space inside the central tube body is the inner cavity of the grout stopper. A plurality of oil cups are arranged on the central tube body, and the plurality of oil cups are evenly arranged along the axial direction.

[0009] The described oil cup includes an oil cup housing arranged inside the central tube body. The outer end and the inner end of the oil cup housing are both open. The outer end of the oil cup housing is close to the inner wall of the expandable outer cylinder, and the inner end of the oil cup housing is close to the inner cavity of the grout stopper. The space inside the oil cup housing is the inner cavity of the oil cup. An oil cup spring is arranged inside the oil cup housing. The outer end of the oil cup spring is fixed on the outer end of the oil cup housing, and an oil cup ball valve is arranged at the inner end of the oil cup spring, and the oil cup ball valve is close to the inner end of the oil cup housing.

[0010] The present invention also has the following technical features:

[0011] Specifically, the described pressure limiting valve includes an upper pressure limiting valve body. A central tube body is fixedly installed inside the front part of the upper pressure limiting valve body. The rear part of the upper pressure limiting valve body is fixedly installed inside the front part of a lower pressure limiting valve body, and a guiding head is fixedly installed on the rear part of the lower pressure limiting valve body.

[0012] The space of the upper pressure limiting valve body from front to back is successively a central tube body installation cavity, a pressure limiting body installation cavity, and a pressure limiting valve inner cavity. On the inner wall of the upper pressure limiting valve body, a first step of the upper pressure limiting valve body and a second step of the upper pressure limiting valve body are successively arranged from front to back. The first step of the upper pressure limiting valve body is located at the junction of the central tube body installation cavity and the pressure limiting body installation cavity, and the second step of the upper pressure limiting valve body is located at the junction of the pressure limiting body installation cavity and the pressure limiting valve inner cavity.

[0013] A central tube body is fixedly installed inside the central tube body installation cavity. A pressure limiting body is movably arranged inside the pressure limiting body installation cavity. A spring seat is arranged inside the pressure limiting valve inner cavity. The front end of the spring seat is integrally arranged with the second step of the upper pressure limiting valve body. A pressure limiting valve slurry hole is opened on the front end of the spring seat, and the rear end of the spring seat is closed. A pressure limiting spring is arranged inside the rear part of the spring seat. The front part of the pressure limiting spring is fixedly installed inside the spring seat, and a pressure limiting body is sleeved inside the rear part of the pressure limiting spring.

[0014] Specifically, a pressure limiting valve sealing gasket is arranged at the rear end of the upper pressure limiting valve body, and the pressure limiting valve sealing gasket is fixedly installed inside the lower pressure limiting valve body. A pressure limiting body sealing ring is arranged on the pressure limiting body.

[0015] Specifically, the safety adapter includes a male safety adapter. A reducing adapter is installed inside the rear part of the male safety adapter. The front part of the male safety adapter is installed inside the female safety adapter. The inner ends of a plurality of safety adapter shear pins are fixedly installed on the front part of the male safety adapter, and the outer ends of the plurality of safety adapter shear pins are fixedly installed on the female safety adapter.

[0016] Specifically, a first step of the female safety adapter and a second step of the female safety adapter are sequentially arranged inside the female safety adapter from the rear to the front; the male safety adapter is sequentially divided into a first section of the male safety adapter, a second section of the male safety adapter, and a third section of the male safety adapter from the rear to the front. A first shoulder of the male safety adapter is arranged at the junction of the first section of the male safety adapter and the second section of the male safety adapter, and the first shoulder of the male safety adapter is close to the first step of the female safety adapter; a second shoulder of the male safety adapter is arranged at the junction of the second section of the male safety adapter and the third section of the male safety adapter, and the second shoulder of the male safety adapter is close to the second step of the female safety adapter.

[0017] Specifically, an external spline is arranged on the second section of the male safety adapter, and an internal spline matching the external spline is arranged inside the female safety adapter.

[0018] Specifically, a safety adapter seal ring is arranged between the third section of the male safety adapter and the female safety adapter.

[0019] Specifically, the check valve includes an upper check valve body. A safety adapter is fixedly installed inside the rear part of the upper check valve body. The front part of the upper check valve body is fixedly installed inside the lower check valve body. A check valve ball spool is movably arranged inside the upper check valve body. The front end of the upper check valve body is covered with a check valve cover, and a check valve slurry hole is opened on the check valve cover.

[0020] Specifically, the inner ends of a plurality of guide head shear pins are fixedly installed on the rear part of the pressure limiting valve, and the outer ends of the plurality of guide head shear pins are fixedly installed on the guide head.

[0021] The present invention also protects a fixed-point grouting method, which uses the fixed-point grouting drill tool as described above. The method specifically includes the following steps:

[0022] Step 1, determine the grouting depth and the setting position.

[0023] Step 2, lower the drillable grouting drill tool:

[0024] Assemble the reducing adapter, the safety adapter, the check valve, the grout stopper, the pressure limiting valve, and the guide head, install the high-pressure sealing drill pipe inside the safety adapter, and then send the high-pressure sealing drill pipe and the assembled drillable grouting drill tool to the setting position selected in Step 1.

[0025] Step 3, setting the packer:

[0026] Through the high-pressure sealed drill pipe and drillable grouting drill tool, grout is injected into the hole at the setting position. At this time, the pressure of the grouting slurry is lower than the working pressure of the pressure limiting valve. The grouting slurry causes the expandable outer cylinder to expand and seal the hole wall at the selected position.

[0027] Step 4, grouting under pressure:

[0028] After completing the setting in Step 3, through the high-pressure sealed drill pipe and drillable grouting drill tool, grout is injected into the hole at the setting position. At this time, the pressure of the grouting slurry is greater than the working pressure of the pressure limiting valve, which can break the shear pin of the guide head and cause the guide head to fall off. After the guide head falls off, the grouting slurry smoothly enters the hole section, and the expandable outer cylinder remains in the set state during the grouting process.

[0029] Step 5, lifting and flushing the drill pipe:

[0030] After completing the grouting in Step 4, use the drill rig to strongly lift the high-pressure sealed drill pipe from the hole opening. After the high-pressure sealed drill pipe is lifted out, remove it and flush it.

[0031] Step 6, waiting for the grout to set and reaming the hole:

[0032] Wait for the grouting slurry injected in Step 4 to solidify. During the waiting period for the grout to set, the expandable outer cylinder remains in the set state all the time; after the waiting period is completed, use the drill rig to drive the drill pipe and drill bit to break the remaining fixed-point grouting drill tool in the long hole, and then continue to drill through the hole section after grouting reinforcement.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] (Ⅰ) For the fixed-point grouting drill tool of the present invention, a packer is used to achieve fixed-point setting, and a pressure limiting valve is used to control the flow direction of the grouting slurry. This drill tool cooperates with the high-pressure sealed drill pipe, can realize fixed-point grouting in the fault zone (broken zone) of the long hole formation, avoid waste caused by full-hole grouting, improve the drilling construction efficiency, and reduce the drilling construction cost.

[0035] (Ⅱ) The fixed-point grouting drill tool of the present invention adopts a safety joint shear pin, which can realize the precise detachment of the high-pressure sealed drill pipe and the drillable grouting drill tool in the hole, and avoid the solidification risk of the high-pressure sealed drill pipe during the waiting period for the grout to set.

[0036] (Ⅲ) The fixed-point grouting method of the present invention ensures drillability while realizing fixed-point grouting in the hole. The fixed-point grouting drill tool can normally break rocks under the action of the drill bit and does not affect the subsequent hole reaming construction. Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the overall structure of a fixed-point grouting drill tool.

[0038] Figure 2 It is a schematic diagram of the structure of a plugging device.

[0039] Figure 3 It is a schematic diagram of the structure of a pressure-limiting valve.

[0040] Figure 4(A) is a schematic diagram of the structure of a safety joint.

[0041] Figure 4(B) is a cross-sectional view of the safety joint.

[0042] Figure 5 It is a schematic diagram of the structure of a check valve.

[0043] The meanings of the labels in the figure are as follows: 1 - reducing joint, 2 - safety joint, 3 - check valve, 4 - plugging device, 5 - pressure-limiting valve, 6 - guide head, 7 - guide head shear pin, 8 - high-pressure sealed drill pipe;

[0044] 201 - male joint of the safety joint, 202 - female joint of the safety joint, 203 - shear pin of the safety joint, 204 - first step of the female joint of the safety joint, 205 - second step of the female joint of the safety joint, 206 - external spline, 207 - internal spline, 208 - sealing ring of the safety joint;

[0045] 301 - upper valve body of the check valve, 302 - lower valve body of the check valve, 303 - ball spool of the check valve, 304 - valve cover of the check valve, 305 - slurry hole of the check valve;

[0046] 401 - expandable outer cylinder, 402 - central pipe body, 403 - inner cavity of the plugging device, 404 - oil cup;

[0047] 501 - upper valve body of the pressure-limiting valve, 502 - installation cavity of the central pipe body, 503 - installation cavity of the pressure-limiting body, 504 - inner cavity of the pressure-limiting valve, 505 - first step of the upper valve body of the pressure-limiting valve, 506 - second step of the upper valve body of the pressure-limiting valve, 507 - pressure-limiting body, 508 - spring seat, 509 - slurry hole of the pressure-limiting valve, 510 - pressure-limiting spring, 511 - sealing washer of the pressure-limiting valve, 512 - sealing ring of the pressure-limiting body;

[0048] 20101 - first section of the male joint of the safety joint, 20102 - second section of the male joint of the safety joint, 20103 - third section of the male joint of the safety joint, 20104 - first shoulder of the male joint of the safety joint, 20105 - second shoulder of the male joint of the safety joint;

[0049] 40401 - oil cup housing, 40402 - inner cavity of the oil cup, 40403 - oil cup spring, 40404 - oil cup ball valve.

[0050] The technical solution of the present invention will be further described below in conjunction with embodiments. Specific embodiments

[0051] It should be noted that all the components and drill pipes used in the present invention are the components and drill pipes known in the art without special description.

[0052] Complying with the above technical solution, the following specific embodiments of the present invention are given. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0053] Embodiment 1:

[0054] This embodiment provides a fixed-point grouting drill tool, as Figure 1 shown, including a reducing joint 1, a safety joint 2, a check valve 3, a grout stopper 4, a pressure limiting valve 5 and a guide head 6 connected in sequence from back to front.

[0055] As Figure 2 shown, the grout stopper 4 includes an expandable outer cylinder 401. A central pipe body 402 is fixedly sleeved inside the expandable outer cylinder 401. The rear end of the central pipe body 402 is flush with the rear end of the expandable outer cylinder 401, and the front end of the central pipe body 402 extends out of the front end of the expandable outer cylinder 401. A check valve 3 is fixedly installed inside the rear part of the central pipe body 402, the front part of the central pipe body 402 is fixedly installed inside the pressure limiting valve 5, and the space inside the central pipe body 402 is the grout stopper inner cavity 403. A plurality of oil cups 404 are arranged on the central pipe body 402, and the plurality of oil cups 404 are evenly arranged along the axial direction.

[0056] The oil cup 404 includes an oil cup housing 40401 arranged inside the central pipe body 402. Both the outer end and the inner end of the oil cup housing 40401 are open. The outer end of the oil cup housing 40401 is close to the inner wall of the expandable outer cylinder 401, the inner end of the oil cup housing 40401 is close to the grout stopper inner cavity 403, and the space inside the oil cup housing 40401 is the oil cup inner cavity 40402. An oil cup spring 40403 is arranged inside the oil cup housing 40401. The outer end of the oil cup spring 40403 is fixed on the outer end of the oil cup housing 40401, and an oil cup ball valve 40404 is arranged at the inner end of the oil cup spring 40403, and the oil cup ball valve 40404 is close to the inner end of the oil cup housing 40401.

[0057] In this embodiment, the expandable outer cylinder 401 is made of an elastic material known in the prior art, such as water-absorbing expandable rubber.

[0058] In this embodiment, when the grouting fluid flows into the inner cavity 403 of the grout stopper, it will spread in the radial direction, applying an outward radial force to the oil cup ball valve 40404. Under the action of this radial force, the oil cup ball valve 40404 compresses the oil cup spring 40403, and the grouting fluid flows into the oil cup inner cavity 40402 through the open inner end of the oil cup housing 40401, and then contacts the inner wall of the expandable outer cylinder 401, causing the expandable outer cylinder 401 to expand after absorbing water, thus achieving setting.

[0059] In this embodiment, both ends of the safety joint 2, the check valve 3, the grout stopper 4, the pressure limiting valve 5, and the guide head 6 are connected in a threaded form.

[0060] As a specific solution of this embodiment, as Figure 3 shown, the pressure limiting valve 5 includes an upper pressure limiting valve body 501. A grout stopper 4 is fixedly installed inside the front part of the upper pressure limiting valve body 501, and the rear part of the upper pressure limiting valve body 501 is fixedly installed inside the lower pressure limiting valve body 502.

[0061] The space of the upper pressure limiting valve body 501 from front to back is successively a central pipe body installation cavity 502, a pressure limiting body installation cavity 503, and a pressure limiting valve inner cavity 504. The inner wall of the upper pressure limiting valve body 501 is successively provided with a first step 505 of the upper pressure limiting valve body and a second step 506 of the upper pressure limiting valve body. The first step 505 of the upper pressure limiting valve body is located at the junction of the central pipe body installation cavity 502 and the pressure limiting body installation cavity 503, and the second step 506 of the upper pressure limiting valve body is located at the junction of the pressure limiting body installation cavity 503 and the pressure limiting valve inner cavity 504.

[0062] A central pipe body 402 is fixedly installed in the central pipe body installation cavity 502. A pressure limiting body 507 is movably arranged in the pressure limiting body installation cavity 503. A spring seat 508 is arranged in the pressure limiting valve inner cavity 504. The front end of the spring seat 508 is integrally provided with the second step 506 of the upper pressure limiting valve body. A pressure limiting valve grouting hole 509 is opened on the front end of the spring seat 508, and the rear end of the spring seat 508 is closed; a pressure limiting spring 510 is arranged inside the rear part of the spring seat 508. The front part of the pressure limiting spring 510 is fixedly installed inside the spring seat 508, and the rear part of the pressure limiting spring 510 is sleeved with the pressure limiting body 507.

[0063] In this embodiment, when the grouting fluid flows into the pressure limiting body installation cavity 503, it will apply an axial force forward to the pressure limiting body 507. When this axial force is greater than the elastic force of the pressure limiting spring 510 itself, the pressure limiting body 507 will compress the pressure limiting spring 510, causing the pressure limiting valve grouting hole 509 to open, and then the grouting fluid will flow into the pressure limiting valve inner cavity 504 through the pressure limiting valve grouting hole 509.

[0064] In this embodiment, most of the components of the pressure limiting valve 5 are non-metallic parts, and individual structural components are made of metal parts. The pressure limiting valve 5 as a whole has drillability.

[0065] As a specific solution of this embodiment, as Figure 3 shown, a pressure-limiting valve sealing gasket 511 is provided at the rear end of the upper valve body 501 of the pressure-limiting valve, and the pressure-limiting valve sealing gasket 511 is fixedly installed in the lower valve body 502 of the pressure-limiting valve; a pressure-limiting body sealing ring 512 is provided on the pressure-limiting body 507.

[0066] As a specific solution of this embodiment, as shown in FIGS. 4(A) and 4(B), the safety joint 2 includes a safety joint male joint 201. A reducing joint 1 is installed inside the rear part of the safety joint male joint 201. The front part of the safety joint male joint 201 is installed inside the safety joint female joint 202. The inner ends of a plurality of safety joint shear pins 203 are fixedly installed on the front part of the safety joint male joint 201, and the outer ends of the plurality of safety joint shear pins 203 are fixedly installed on the safety joint female joint 202. When the force for pulling out the fixed-point grouting drill tool outward is greater than the frictional force between the fixed-point grouting drill tool and the packer seating hole wall and the drillable grouting drill tool, the safety joint shear pins 203 will be broken to ensure that the high-pressure sealed drill pipe 8 can be smoothly withdrawn.

[0067] As a specific solution of this embodiment, as shown in FIGS. 4(A) and 4(B), a first step 204 of the safety joint female joint and a second step 205 of the safety joint female joint are sequentially arranged inside the safety joint female joint 202 from the rear to the front; the safety joint male joint 201 is sequentially divided into a first section 20101 of the safety joint male joint, a second section 20102 of the safety joint male joint, and a third section 20103 of the safety joint male joint from the rear to the front. A first shoulder 20104 of the safety joint male joint is provided at the junction of the first section 20101 and the second section 20102 of the safety joint male joint, and the first shoulder 20104 of the safety joint male joint is close to the first step 204 of the safety joint female joint; a second shoulder 20105 of the safety joint male joint is provided at the junction of the second section 20102 and the third section 20103 of the safety joint male joint, and the second shoulder 20105 of the safety joint male joint is close to the second step 205 of the safety joint female joint.

[0068] As a specific solution of this embodiment, as shown in FIGS. 4(A) and 4(B), an external spline 206 is provided on the second section 20102 of the safety joint male joint, and an internal spline 207 matching the external spline 206 is provided inside the safety joint female joint 202; the safety joint male joint 201 and the safety joint female joint 202 are fixedly connected through the external spline 206 and the internal spline 207.

[0069] As a specific solution of this embodiment, as shown in FIGS. 4(A) and 4(B), a safety joint sealing ring 208 is provided between the third section 20103 of the safety joint male connector and the safety joint female connector 202; the function of the safety joint sealing ring 208 is to ensure the sealed connection between the safety joint male connector 201 and the safety joint female connector 202.

[0070] As a specific solution of this embodiment, as Figure 5 shown, the check valve 3 includes an upper check valve body 301, a safety joint 2 is fixedly installed inside the rear part of the upper check valve body 301, the front part of the upper check valve body 301 is fixedly installed inside the lower check valve body 302, a check valve ball spool 303 is movably arranged inside the upper check valve body 301, the front end of the upper check valve body 301 is covered with a check valve cap 304, and a check valve slurry hole 305 is opened on the check valve cap 304; the check valve 3 can prevent the slurry entering the grout stopper 4 from flowing back.

[0071] Embodiment 2:

[0072] This embodiment provides a fixed-point grouting method, which uses the fixed-point grouting drill in Embodiment 1. This method specifically includes the following steps:

[0073] Step 1, determine the grouting depth and setting position:

[0074] When encountering complex strata during directional drilling construction, the downhole directional drilling drill is withdrawn, the downhole borescope is lowered to determine the borehole depth and the integrity of the entire borehole wall, the setting position is selected, and the required grouting volume is roughly calculated according to the grouting pressure diffusion range.

[0075] Step 2, lower the drillable grouting drill:

[0076] Assemble the reducing joint 1, the safety joint 2, the check valve 3, the grout stopper 4, the pressure limiting valve 5 and the guide head 6, install the high-pressure sealed drill pipe 8 inside the safety joint 2, and then send the high-pressure sealed drill pipe 8 and the assembled drillable grouting drill to the setting position selected in Step 1, that is, the hole section close to the fault zone and fracture zone in the hole and with relatively complete hole wall.

[0077] Step 3, set the grout stopper:

[0078] Through the high-pressure sealed drill pipe 8 and the drillable grouting drill, inject slurry into the hole at the setting position. At this time, the pressure of the grouting slurry is lower than the working pressure of the pressure limiting valve 5, and the grouting slurry causes the expandable outer cylinder 401 to expand and seal the hole wall at the selected position.

[0079] Step 4, grout under pressure:

[0080] After the setting in Step 3 is completed, grout is injected into the hole at the setting position through the high-pressure sealed drill pipe 8 and the drillable grouting tool. At this time, the pressure of the grouting slurry is greater than the working pressure of the pressure limiting valve 5, which can break the shear pin 7 of the guide head, causing the guide head to fall off. After the guide head falls off, the grouting slurry smoothly enters the hole section of the fault zone and broken zone. During the grouting process, the expandable outer cylinder 401 is always in the set state.

[0081] Step 5, lift and flush the drill pipe:

[0082] After the grouting in Step 4 is completed, the high-pressure sealed drill pipe 8 is strongly lifted from the hole mouth by the drill rig. After the shear pin 203 of the safety joint is broken, the drill pipe 8 and the drill tools after the shear pin 203 of the safety joint are separated, and then the high-pressure sealed drill pipe 8 is lifted out, removed and flushed.

[0083] Step 6, waiting for the grout to set and reaming the hole:

[0084] After waiting for the grouting slurry injected in Step 4 to solidify, during the waiting period for the grout to set, the expandable outer cylinder 401 is always in the set state; after the waiting period is completed, the drill rig drives the drill pipe and the drill bit to break the remaining fixed-point grouting tools in the long hole, and then continues to drill through the fault zone and broken zone strata after grouting reinforcement.

Claims

1. A fixed-point grouting drill tool, characterized in that It includes a reducing adapter (1), a safety adapter (2), a check valve (3), a grout stopper (4), a pressure limiting valve (5) and a guide head (6) connected in sequence from back to front; The grout stopper (4) includes an expandable outer cylinder (401). A central tube body (402) is fixedly sleeved inside the expandable outer cylinder (401). The rear end of the central tube body (402) is flush with the rear end of the expandable outer cylinder (401), and the front end of the central tube body (402) extends out of the front end of the expandable outer cylinder (401). A check valve (3) is fixedly installed inside the rear part of the central tube body (402). The front part of the central tube body (402) is fixedly installed inside the pressure limiting valve (5). The space inside the central tube body (402) is the grout stopper inner cavity (403). A plurality of oil cups (404) are arranged on the central tube body (402), and the plurality of oil cups (404) are evenly arranged along the axial direction; The oil cup (404) includes an oil cup housing (40401) arranged inside the central tube body (402). Both the outer end and the inner end of the oil cup housing (40401) are open. The outer end of the oil cup housing (40401) is close to the inner wall of the expandable outer cylinder (401), and the inner end of the oil cup housing (40401) is close to the grout stopper inner cavity (403). The space inside the oil cup housing (40401) is the oil cup inner cavity (40402). An oil cup spring (40403) is arranged inside the oil cup housing (40401). The outer end of the oil cup spring (40403) is fixed to the outer end of the oil cup housing (40401), and an oil cup ball valve (40404) is arranged at the inner end of the oil cup spring (40403). The oil cup ball valve (40404) is close to the inner end of the oil cup housing (40401); The pressure limiting valve (5) includes an upper pressure limiting valve body (501). A central tube body (402) is fixedly installed inside the front part of the upper pressure limiting valve body (501). The rear part of the upper pressure limiting valve body (501) is fixedly installed inside the front part of a lower pressure limiting valve body (502). A guide head (6) is fixedly installed on the rear part of the lower pressure limiting valve body (502); The space of the upper pressure limiting valve body (501) is sequentially a central tube body installation cavity (502), a pressure limiting body installation cavity (503) and a pressure limiting valve inner cavity (504) from front to back. A first upper pressure limiting valve body step (505) and a second upper pressure limiting valve body step (506) are sequentially arranged on the inner wall of the upper pressure limiting valve body (501) from front to back. The first upper pressure limiting valve body step (505) is located at the junction of the central tube body installation cavity (502) and the pressure limiting body installation cavity (503), and the second upper pressure limiting valve body step (506) is located at the junction of the pressure limiting body installation cavity (503) and the pressure limiting valve inner cavity (504); A central pipe body (402) is fixedly installed in the described central pipe body installation cavity (502), a pressure limiting body (507) is movably arranged in the pressure limiting body installation cavity (503), a spring seat (508) is arranged in the pressure limiting valve inner cavity (504), the front end of the spring seat (508) is integrally provided with the second step (506) of the upper valve body of the pressure limiting valve, a pressure limiting valve slurry hole (509) is opened on the front end of the spring seat (508), and the rear end of the spring seat (508) is closed; a pressure limiting spring (510) is arranged in the rear part of the spring seat (508), the front part of the pressure limiting spring (510) is fixedly installed in the spring seat (508), and the rear part of the pressure limiting spring (510) is sleeved with the pressure limiting body (507).

2. The fixed-point grouting drill tool according to claim 1, wherein A pressure limiting valve sealing gasket (511) is arranged at the rear end of the described upper valve body (501) of the pressure limiting valve, and the pressure limiting valve sealing gasket (511) is fixedly installed in the lower valve body (502) of the pressure limiting valve; a pressure limiting body sealing ring (512) is arranged on the pressure limiting body (507).

3. The fixed-point grouting drill tool according to claim 1, characterized in that The described safety adapter (2) includes a safety adapter male joint (201), a reducing adapter (1) is installed inside the rear part of the safety adapter male joint (201), the front part of the safety adapter male joint (201) is installed inside the safety adapter female joint (202), the inner ends of a plurality of safety adapter shear pins (203) are fixedly installed on the front part of the safety adapter male joint (201), and the outer ends of the plurality of safety adapter shear pins (203) are fixedly installed on the safety adapter female joint (202).

4. The fixed-point grouting drill tool according to claim 3, wherein A first step (204) of the safety adapter female joint and a second step (205) of the safety adapter female joint are sequentially arranged inside the described safety adapter female joint (202) from back to front; the safety adapter male joint (201) is sequentially divided into a first section (20101) of the safety adapter male joint, a second section (20102) of the safety adapter male joint, and a third section (20103) of the safety adapter male joint from back to front. A first shoulder (20104) of the safety adapter male joint is arranged at the junction of the first section (20101) of the safety adapter male joint and the second section (20102) of the safety adapter male joint, and the first shoulder (20104) of the safety adapter male joint is close to the first step (204) of the safety adapter female joint; a second shoulder (20105) of the safety adapter male joint is arranged at the junction of the second section (20102) of the safety adapter male joint and the third section (20103) of the safety adapter male joint, and the second shoulder (20105) of the safety adapter male joint is close to the second step (205) of the safety adapter female joint.

5. The fixed-point grouting drill tool according to claim 4, characterized in that, An external spline (206) is arranged on the second section (20102) of the safety adapter male joint, and an internal spline (207) matching the external spline (206) is arranged inside the safety adapter female joint (202).

6. The fixed-point grouting drill tool according to claim 4, wherein A safety adapter sealing ring (208) is arranged between the third section (20103) of the safety adapter male joint and the safety adapter female joint (202).

7. The fixed-point grouting drill tool according to claim 1, characterized in that, The check valve (3) described above includes an upper check valve body (301). A safety adapter (2) is fixedly installed inside the rear part of the upper check valve body (301). The front part of the upper check valve body (301) is fixedly installed inside the lower check valve body (302). A check valve ball spool (303) is movably arranged inside the upper check valve body (301). The front end of the upper check valve body (301) is covered with a check valve cover (304). A check valve slurry hole (305) is opened on the check valve cover (304).

8. The fixed-point grouting drill tool according to claim 1, characterized in that, The inner ends of a plurality of guide head shear pins (7) are fixedly installed on the rear part of the pressure limiting valve (5). The outer ends of the plurality of guide head shear pins (7) are fixedly installed on the guide head (6).

9. A fixed-point grouting method, characterized in that, This method uses the fixed-point grouting drill described in any one of claims 1 to 8. Specifically, this method includes the following steps: Step 1, determine the grouting depth and the setting position; Step 2, lower the drillable grouting drill: Assemble the variable diameter adapter (1), safety adapter (2), check valve (3), grout stopper (4), pressure limiting valve (5) and guide head (6), and install the high-pressure sealed drill pipe (8) inside the safety adapter (2). Then, send the high-pressure sealed drill pipe (8) and the assembled drillable grouting drill to the setting position selected in Step 1; Step 3, set the grout stopper: Through the high-pressure sealed drill pipe (8) and the drillable grouting drill, inject slurry into the hole at the setting position. At this time, the pressure of the grouting slurry is lower than the working pressure of the pressure limiting valve (5). The grouting slurry causes the expandable outer cylinder (401) to expand and seal the hole wall at the selected position; Step 4, grout under pressure: After completing the setting in Step 3, through the high-pressure sealed drill pipe (8) and the drillable grouting drill, inject slurry into the hole at the setting position. At this time, the pressure of the grouting slurry is greater than the working pressure of the pressure limiting valve (5), which can break the guide head shear pins (7) and cause the guide head to fall off. After the guide head falls off, the grouting slurry smoothly enters the hole section. During the grouting process, the expandable outer cylinder (401) is always in the set state; Step 5, lift and flush the drill pipe: After completing the grouting in Step 4, use the drilling rig to strongly lift the high-pressure sealed drill pipe (8) from the hole mouth. After the high-pressure sealed drill pipe (8) is lifted out, remove it and flush it; Step 6, wait for the slurry to set and ream the hole: Wait for the grouting slurry injected in Step 4 to solidify. During the waiting period for the slurry to set, the expandable outer cylinder (401) is always in the set state. After the waiting period is completed, use the drilling rig to drive the drill pipe and drill bit to break the remaining fixed-point grouting drill in the long hole, and then continue to drill through the hole section after grouting reinforcement.

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