Porous compression type underground grouting anchor rod suitable for multi-fissure rock stratum and method of porous compression type underground grouting anchor rod

Abstract

The invention belongs to the technical field of grouting supporting, and discloses a porous compression type underground grouting anchor rod suitable for a multi-fissure rock stratum and a method thereof.The anchor rod comprises a hollow grouting anchor rod body, an anchor head fixing piece and an anchor tail fixing piece, the anchor head fixing piece and the anchor tail fixing piece are arranged at the two ends of the grouting anchor rod body respectively, and a plurality of grout overflow holes are formed in the grouting anchor rod body in the length direction of the grouting anchor rod body; the grouting anchor rod further comprises a grouting assembly, the grouting assembly comprises a grouting rod, the grouting rod is a hollow grouting rod, the grouting rod is arranged in a hollow cavity of the grouting anchor rod in a penetrating mode in the axis direction of the grouting anchor rod, one end of the grouting rod extends to the area close to the anchor head fixing piece, and the free end of the grouting rod extends out of the end of the anchor tail fixing piece; according to the scheme, the grouting rod extends to the lower area, close to the anchor head fixing piece, of the anchor hole, the bottom of the anchor hole is filled with grout firstly, and cavities and bubble residues are reduced; the grouting anchor rod solves the problem that grout is not full during grouting of multiple grout overflow holes of an existing grouting anchor rod, and is suitable for grouting support of multi-fissure rock strata.

Description

Technical Field

[0001] This solution belongs to the field of grouting support technology, specifically involving a porous compressible downhole grouting anchor bolt and its method suitable for multi-fractured rock formations. Background Technology

[0002] In underground mining operations, fractured rock strata are affected by geological tectonic movements (such as fault activity and rock compression) and disturbances from early-stage blasting, forming complex rock strata with numerous, interconnected fractures. Compared to well-integrity general rock strata (such as intact limestone and sandstone), fractured rock strata have a uniaxial compressive strength of only 30%-60% of that of intact rock strata, exhibiting significant heterogeneity (large differences in strength and permeability between different areas). Once subjected to external loads from underground mining (such as roof pressure and excavation unloading reaction forces), the internal fractures can easily expand and connect rapidly, ultimately leading to rock mass instability.

[0003] Because underground mining requires the excavation of tunnels and working areas, the already fragile internal fractures in fractured rock strata can expand rapidly after excavation and unloading, leading to a series of safety risks. This problem can be solved by anchor bolt grouting support. Grouting injects cement-based materials into the anchor holes and surrounding rock fractures. After the grout solidifies, it fills the fracture spaces and cements loose rock debris. Simultaneously, the anchor bolts penetrate deep into the stable rock strata, providing active support to the grouted rock mass, restraining deformation trends, and ensuring the safe progress of underground mining operations.

[0004] See the existing publication (announcement) number CN113107560A, which discloses a reinforced anchoring type pressure-yielding grouting anchor bolt anchoring device and its usage method in a broken coal roadway. The device includes a hollow grouting anchor bolt, the tail of which is provided with a resistance-increasing ratchet sleeve. The grout stop passing through the hollow grouting anchor bolt is located at the orifice of the anchor hole. A constant resistance pressure-yielding structure is provided in conjunction with the hollow grouting anchor bolt. The constant resistance pressure-yielding structure includes an elastic pressure-yielding component and a plastic pressure-yielding component that are axially superimposed. The rod body of the hollow grouting anchor bolt contains multiple overflow holes.

[0005] For example, the aforementioned grouting anchor bolts, although multiple overflow holes are set along the length of the anchor bolt to improve the grouting range and efficiency, the grout will preferentially flow out from the overflow hole closer to the grouting opening due to the difference in flow resistance during grouting, rather than being discharged from the lower overflow hole in the order from the bottom of the anchor hole to the opening. This will make it difficult for the air in the lower part of the anchor hole (especially the bottom area) to be discharged with the grout. A large amount of air will be blocked in the bottom of the hole and the lower fissures, forming bubbles or cavities. At the same time, the grout will not be able to fully reach the bottom of the hole and the lower rock mass fissures, resulting in insufficient grout filling in the bottom anchoring section. Consequently, the bond strength between the lower part of the anchor bolt and the rock mass will be significantly insufficient, making it impossible to form stable and reliable support for complex strata such as broken coal roadways. Summary of the Invention

[0006] The purpose of this solution is to provide a porous compression-type downhole grouting anchor suitable for multi-fractured rock formations, in order to solve the problem of insufficient grout filling during grouting of existing grouting anchors with multiple overflow holes.

[0007] To achieve the above objectives, this solution provides a porous compression-type downhole grouting anchor suitable for fractured rock formations, comprising a hollow grouting anchor and anchor head and anchor tail fixing components respectively located at both ends of the grouting anchor. The grouting anchor has several overflow holes along its length and also includes a grouting assembly, which includes: The grouting rod is hollow and passes through the hollow cavity of the grouting anchor rod along the axial direction of the grouting anchor rod. One end of the grouting rod extends to the area near the anchor head fixing member, and the free end extends out of the end of the anchor tail fixing member.

[0008] The principle and effect of this scheme are as follows: (1) After the grouting anchor rod is fixed in the anchor hole through the anchor head fixing part and the anchor tail fixing part, the hollow grouting rod passes through its inner cavity along the axis of the grouting anchor rod. The external grouting device injects grout through the free end of the grouting rod extending out of the anchor tail fixing part. The grout is transported along the inner cavity of the grouting rod to the area near the anchor head fixing part, and then flows from the anchor head fixing part to the anchor tail fixing part, and is injected into the anchor hole through the overflow hole. (2) Compared with the existing grouting anchor rod with multiple overflow holes, this scheme extends the grouting rod to the lower part of the anchor hole near the anchor head fixing part, so that the grout fills the bottom of the anchor hole first, avoiding the problem of insufficient grout during grouting caused by the grout preferentially flowing out from the overflow hole near the hole opening of the existing anchor rod, and reducing voids and air bubbles.

[0009] Furthermore, the outer wall of the grouting anchor is provided with a spiral external thread along its length, and the overflow hole passes through the spiral external thread and communicates with the hollow cavity of the grouting anchor.

[0010] The principle and effect of this solution are as follows: compared with traditional cylindrical anchor bolts, the spiral interlocking structure formed after the grout solidifies increases the pull-out resistance and is more suitable for the support needs of fractured rock formations.

[0011] Furthermore, it also includes a cleaning component, which includes a fan blade and a sleeve. The fan blade's rotating shaft is threadedly connected to the outer wall of the grouting anchor rod, and the sleeve is coaxially rotatably arranged with the fan blade. The fan blade is used to clean the overflow hole. It also includes a drive component for driving the fan blade to rotate circumferentially along the length direction of the grouting anchor rod.

[0012] The principle and effect of this solution are as follows: After installing the grouting anchor bolt in the anchor hole, even before grouting begins, the fractured rock strata themselves contain a large amount of loose rock debris and dust, which will fall into the overflow hole, easily causing the overflow hole to become blocked before grouting. If it is not cleaned in advance, the grout cannot diffuse normally through the blocked overflow hole during subsequent grouting, affecting the filling effect. In this solution, because the fan blade's shaft is threadedly connected to the outer wall of the grouting anchor bolt, the drive assembly drives the fan blade to rotate circumferentially along the length of the grouting anchor bolt, causing the fan blade to rotate and generate airflow, thereby blowing away and cleaning the impurities in the overflow hole, thus ensuring the overflow hole is unobstructed.

[0013] Furthermore, the driving assembly includes a float plate, which is disposed between the fan blade and the anchor head fixing component, and the float plate is coaxially and fixedly connected to the fan blade. The float plate cooperates with the grout, and the grout is used to drive the float plate to move along the length direction of the grouting anchor rod, so as to drive the fan blade to rotate circumferentially along the length direction of the grouting anchor rod.

[0014] The principle and effect of this scheme are as follows: During grouting, the grout flows from the area near the anchor head fixing component towards the anchor tail. When it flows through the floating plate, the thrust of the grout drives the floating plate to move towards the anchor tail along the length of the grouting anchor rod. Since the fan blade is fixedly connected to the floating plate, the axial movement of the floating plate is converted into the circumferential rotation of the fan blade through the threaded engagement between the fan blade and the grouting anchor rod, so that the fan blade continues to rotate circumferentially along the length of the grouting anchor rod, thereby removing impurities in the overflow hole.

[0015] Furthermore, a stirring blade is coaxially fixed to one end of the float near the anchor head fixing member, and the stirring blade is used to stir the slurry.

[0016] The principle and effect of this scheme are as follows: During grouting, the grout flows from the anchor head fixing area towards the anchor tail, meaning the grout at the bottom pushes the grout at the top, resulting in poor fluidity of the grout on the surface and affecting its diffusion. In this scheme, during grouting, the grout drives the float plate to move axially, which in turn drives the agitator blades to rotate. The rotating blades agitate the grout surface, causing the grout to flow and diffuse into the rock fissures.

[0017] Furthermore, the drive assembly includes an impeller and a slider. The impeller is coaxially and fixedly connected to the grout outlet of the grouting rod. The side wall of the impeller shaft is provided with a grout spray nozzle, which communicates with the hollow cavity of the grouting rod. The outer wall of the grouting rod is provided with an external thread. The slider is threadedly connected to the outer wall of the grouting rod, and the outer wall of the slider is slidably connected to the inner wall of the grouting anchor rod. The sleeve is a ferromagnetic sleeve, and the slider is a magnetic slider used to attract the sleeve.

[0018] The principle and effect of this scheme are as follows: when the grout is sprayed out of the nozzle through the hollow cavity of the grouting rod, the impact force will drive the impeller to rotate. The rotation of the impeller not only agitates the grout, making the grout more fluid, but also drives the grouting rod to rotate, thereby driving the slider to move along the length of the grouting rod towards the anchor tail. Since the slider is a magnetic slider and the sleeve is a ferromagnetic sleeve, when the slider moves, it will attract the sleeve to move synchronously through magnetic attraction, thereby driving the fan blade to rotate continuously, thereby clearing impurities in the overflow hole.

[0019] Furthermore, the slider is provided with a groove, and a puncture needle for cleaning the overflow hole is provided in the groove. The puncture needle is connected to a compression spring, and the free end of the compression spring is fixedly connected to the groove.

[0020] The principle and effect of this scheme are as follows: the impeller drives the grouting rod to rotate synchronously, and the external thread on the outer wall of the grouting rod drives the slider to slide along the inner wall of the grouting anchor. During the movement of the slider, the piercing needle has a thrust towards the inner wall of the grouting anchor under the action of the elastic force of the compression spring. When the slider slides to the point where the piercing needle is aligned with a certain overflow hole, the compression spring will push the piercing needle to insert into the overflow hole. The piercing needle can fix the rock debris in the hole to the outside of the grouting anchor, completing the cleaning of a single hole. As the slider continues to slide along the axial direction of the grouting rod, the piercing needle will sequentially align with and clean each overflow hole, cleaning all overflow holes one by one. With the help of the fan blade's wind force, the cleaning of the overflow holes is further improved.

[0021] Furthermore, the grouting rod includes a fixed rod section, and the fixed rod is coaxially rotatably connected to the grouting rod. The outer wall of the fixed rod is provided with an external thread, and the inner wall of the grouting anchor rod is provided with an internal thread that mates with the external thread.

[0022] The principle and effect of this solution are as follows: the fixed rod is threadedly connected to the grouting anchor rod, which is used to support and fix the grouting rod.

[0023] A method for porous compressible downhole grouting in fractured rock formations includes the application of a porous compressible downhole grouting anchor bolt as described above, comprising the following steps: Step S10: Lower the grouting anchor into the anchor hole, center the grouting anchor, fix the front end of the grouting anchor with the anchor head fixing component, and fix the rear end of the grouting anchor with the anchor tail fixing component; Step S20: Insert the grouting rod into the inner cavity along the axis of the grouting anchor rod, so that one end of the grouting rod extends to the area near the anchor head fixing component, lock the axial position of the grouting rod, and then seal the free end of the grouting rod extending out of the anchor tail fixing component with the external grouting device. Step S30: Start the external grouting device. The grout is delivered to the area near the anchor head fixing part through the grouting rod and flows towards the anchor tail. The fan blade is driven by the drive component to rotate circumferentially along the length of the grouting anchor rod to clean the overflow hole and stir the grout. Step S40: When the grouting pressure reaches its limit, continue grouting until the grout overflows evenly from the liquid inlet of the grouting rod without any air bubbles. Then, close the grouting device and wait for the grout to solidify to complete the support. Finally, screw the sealing plug into the tail of the grouting rod.

[0024] Furthermore, in step S30, the thrust generated by the slurry flow drives the float plate to move towards the anchor tail along the length of the grouting anchor rod. The float plate drives the fan blades to rotate circumferentially by driving the fan blades to move synchronously. The airflow generated is used to clean the overflow hole. At the same time, it drives the stirring blades to rotate, agitating the surface of the slurry and improving its fluidity.

[0025] Furthermore, in step S30, the grout flows through the grouting rod to the spray nozzle of the impeller and is sprayed out, driving the impeller to rotate coaxially, which in turn drives the grouting rod to rotate, and drives the slider to move axially along the inner wall of the grouting anchor rod, so that the piercing needles are aligned one by one and inserted into each overflow hole under the pre-tightening force of the compression spring, which drives the fan blade to rotate and generate airflow to assist in cleaning the overflow holes. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a porous compressible downhole grouting anchor bolt suitable for fractured rock formations according to the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the cleaning component and drive component structure of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of the cleaning component and drive component structure of the present invention. Figure 2 ; Figure 4 This is a schematic diagram of the cleaning component and drive component structure of the present invention. Figure 3 .

[0027] The reference numerals in the accompanying drawings include: grouting anchor 1, overflow hole 11, spiral external thread 12, anchor head fixing component 2, anchor tail fixing component 3, pad 31, grouting assembly 4, grouting rod 41, fixing rod 411, sealing plug 412, cleaning assembly 5, fan blade 51, sleeve 52, drive assembly 6, float 61, mixing blade 62, impeller 63, grout nozzle 631, slider 64, groove 641, puncture needle 65, and compression spring 651. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] The following describes in detail, with reference to the accompanying drawings, an embodiment of the present invention, a porous compressible downhole grouting anchor suitable for multi-fractured rock formations. Please refer to the accompanying drawings. Figures 1-2 The core consists of grouting anchor bolt 1, anchor head fixing component 2, anchor tail fixing component 3, grouting assembly 4, cleaning assembly 5, and driving assembly 6. The specific structure and connection relationship are as follows: Example 1: Please see Figure 1 and Figure 2 The grouting anchor 1 is a hollow tubular structure made of steel reinforcement. Its outer wall is integrally formed with a spiral external thread 12 along its length. The pitch of the spiral external thread 12 is set to 20-30mm, which enhances the interlocking area with the grout and improves the contact stability between the anchor and the rock mass. Several overflow holes 11 are evenly distributed along the length and circumference of the grouting anchor 1. The diameter of the overflow holes 11 is 6-10mm, distributed in a quincunx pattern, and completely penetrates the spiral external thread 12. These holes are fully connected to the hollow cavity inside the grouting anchor 1, allowing the grout to smoothly diffuse from the hollow cavity through the overflow holes 11 into the anchor hole and rock fissures. After solidification, a spiral interlocking structure is formed, improving the anchor's pull-out resistance and adapting to the support requirements of fractured rock formations. Anchor head fixing component 2 and anchor tail fixing component 3 are respectively assembled at both ends of grouting anchor rod 1. Both are existing technologies and are fixed to grouting anchor rod 1 by threaded connection. The end of anchor head fixing component 2 is set with an inverted conical structure to facilitate the smooth insertion of grouting anchor rod 1 into the anchor hole. Anchor tail fixing component 3 has a through hole in the middle for grouting rod 41 to pass through, and a sealing gasket (not shown) is set on the inner wall of the through hole. Anchor tail fixing component 3 includes a pad 31, and the pad 31 has a vent hole (not shown) for gas in the anchor hole to be discharged from the vent hole during grouting.

[0032] Please continue reading. Figure 2 The grouting assembly 4 includes a grouting rod 41, which is also a hollow tubular structure made of the same material as the grouting anchor rod 1. It passes through the hollow cavity along the axial direction of the grouting anchor rod 1. One end of the grouting rod 41 extends to the area near the anchor head fixing member 2, 50-80mm from the end of the anchor head fixing member 2. The free end extends beyond the end of the anchor tail fixing member 3, with a reserved length of 200-300mm for easy connection to an external grouting device. A fixing rod 411 is provided at the tail of the grouting rod 41. The fixing rod 411 and the grouting rod 41 are coaxially rotatably connected via a bearing. The outer wall of the fixing rod 411 is machined with external threads, which mesh with the internal threads pre-set on the inner wall of the grouting anchor rod 1. By rotating the fixing rod 411, the axial position of the grouting rod 41 can be locked to prevent displacement during grouting. The tail of the fixing rod 411 is detachably provided with a sealing plug 412. After grouting is completed, the sealing plug 412 is inserted into the tail of the fixing rod 411 to seal the fixing rod 411.

[0033] Please continue reading. Figure 2 The cleaning component 5 includes a fan blade 51 and a sleeve 52. The central shaft of the fan blade 51 is threaded to the outer wall of the grouting anchor rod 1, and the thread direction of the shaft is consistent with the thread direction of the outer wall of the grouting rod 41. The sleeve 52 is fitted outside the shaft of the fan blade 51 and rotates coaxially with the shaft through bearings, so that the fan blade 51 rotates stably. The fan blade 51 is made of 304 stainless steel sheet with a thickness of 1.5-2mm. It consists of 3-4 arc-shaped blades with a bending angle of 50 degrees and the blade edges are ground. This material is lightweight and wear-resistant, and can generate sufficient airflow when rotating. The airflow is directed towards the anchor tail, and the disturbed airflow can cover the outer wall of the grouting anchor rod 1, thereby cleaning the overflow hole 11. It should be noted that, since the fan blade 51 needs to rotate along the length of the grouting anchor rod 1, those skilled in the art need to set a large lead angle between the thread on the outer wall of the grouting rod 1 and the internal thread in the rotating shaft of the fan blade 51, that is, the thread spacing between two adjacent threads needs to be set to be large, so that the fan blade 51 can be driven to move along the length of the grouting anchor rod 1, and is in a circumferential rotation state during the movement.

[0034] Please continue reading. Figure 2In this embodiment, the drive assembly 6 includes a float plate 61 and a stirring blade 62, which together form a linkage transmission structure with the fan blade 51 without additional power. The float plate 61 is located between the fan blade 51 and the anchor head fixing component 2, and is coaxially fixedly connected to the fan blade 51. The float plate 61 is made of lightweight, high-strength nylon material, with a density lower than that of the grout (cement-based grout density is approximately 1.8-2.0 g / cm³), minimizing grout pushing resistance and allowing the float plate 61 to move smoothly under the small thrust of the grout flow. The float plate 61 is designed as a circular disc, with a through hole (not shown) at its center for the outer wall of the grouting anchor rod 1 to pass through. The diameter of the float plate 61 is 0.5- smaller than the diameter of the anchor hole. The 1mm gap prevents friction between the float plate 61 and the inner wall of the anchor hole, and also reduces grout leakage from the edges of the float plate 61 and the inner wall of the anchor hole. The mixing blade 62 is also made of 304 stainless steel. The blade is an arc-shaped thin steel sheet with a thickness of 1mm. There are 3 blades evenly distributed around the central axis of the float plate 61. The root of the blade is coaxially fixed to the end of the float plate 61 near the anchor head fixing part 2 by welding. The tip of the mixing blade 62 maintains a 1.5mm gap with the inner wall of the grouting anchor rod 1, which not only avoids friction during rotation, but also maximizes the coverage of the grout surface area and improves the mixing effect.

[0035] After the grouting operation is started, the external grouting device pressurizes and injects cement-based grout (density approximately 1.8-2.0 g / cm³) into the hollow grouting rod 41. The grout is continuously delivered along the inner cavity of the grouting rod 41 to the area near the anchor head fixing component 2 (50-80 mm from the end of the anchor head fixing component 2), and then flows along the hollow cavity of the grouting anchor rod 1 towards the anchor tail fixing component 3. The continuous thrust generated by the grout flow will push the float plate 61 to move axially towards the anchor tail end along the length of the grouting anchor rod 1; the float plate 61 drives the fan blade 51 to move synchronously, and the threads on the inner wall of the central rotating shaft of the fan blade 51 and the outer wall of the grouting anchor rod 1 adopt a large lead angle design (large spacing between adjacent threads). When the rotating shaft is subjected to the axial thrust transmitted by the float plate 61, the thread meshing structure converts the axial movement into circumferential rotational motion, causing the fan blade 51 to rotate spirally along the length of the grouting anchor rod 1. When the fan blade 51 rotates, it generates airflow towards the anchor tail, covering the entire outer wall area of ​​the grouting anchor 1. This airflow blows away rock debris and dust from the overflow hole 11, clearing impurities from the opening of the overflow hole 11. Simultaneously, as the float 61 moves, the stirring blade 62 rotates synchronously with it, agitating the surface grout and causing it to flow and diffuse into the rock fissures. As grouting continues, the grout gradually fills the anchor hole and rock fissures. After solidification, it forms a tight spiral interlocking structure with the spiral external threads 12 on the outer wall of the grouting anchor 1, significantly improving the anchor's pull-out resistance and ultimately forming a stable and reliable multi-fracture rock support system.

[0036] Example 2: The difference between this embodiment and the previous embodiment is that in the previous embodiment, only the fan blade 51 was used to clean the overflow hole 11, but some impurities had already become stuck inside the overflow hole 11, so further cleaning of the overflow hole 11 was required. This embodiment makes further improvements based on the previous embodiment. In this embodiment, the grouting anchor 1 and grouting rod 41 are made of non-magnetic high-strength alloy material, and the float plate 61 and stirring blade 62 are eliminated. The specific structure is as follows: Please see Figure 3 and Figure 4 The drive assembly 6 includes an impeller 63 and a slider 64. The impeller 63 is coaxially and fixedly connected to the grout outlet at the head of the grouting rod 41. The impeller 63 is made of lightweight alloy, and several grouting nozzles 631 are evenly opened along the circumference on the side wall of its central rotating shaft. The grouting nozzles 631 are connected to the hollow cavity of the grouting rod 41 to ensure that the grout can be sprayed out smoothly.

[0037] Please continue reading. Figure 3 and Figure 4 The driving component 6 includes a slider 64, a piercing needle 65, and a compression spring 651. In this embodiment, the outer wall of the grouting rod 41 is machined with external threads, and the inner wall of the slider 64 is provided with a matching internal thread. The two are threadedly connected, and the outer wall of the slider 64 has a horizontal protrusion (not shown). The inner wall of the grouting anchor rod 1 has a horizontally arranged groove (not shown) that mates with the protrusion, and the groove extends along the length of the grouting anchor rod 1 to its tail, allowing the outer wall of the slider 64 to slide against the inner wall of the grouting anchor rod 1, enabling axial movement along the length of the grouting anchor rod 1. The slider 64 is made of neodymium iron boron permanent magnet and is a magnetic slider. The sleeve 52 of the cleaning component 5 is made of ferromagnetic stainless steel, and the two can be synchronously linked by magnetic attraction. The slider 64 has several vertically arranged grooves 641 evenly distributed around its circumference. The number of grooves 641 is the same as the number of overflow holes 11 on the same cross section of the grouting anchor rod 1 and they are distributed accordingly. The piercing needle 65 is located in the groove 641 and is made of hard alloy. Its end is conical and has an arc-shaped transition chamfer to facilitate insertion into the overflow hole 11. The tail of the piercing needle 65 is fixedly connected to one end of the compression spring 651. The compression spring 651 is a cylindrical helical compression spring, and its free end is fixed to the bottom of the groove 641. The initial preload is set to 5-8N so that the piercing needle 65 always has a thrust towards the inner wall of the grouting anchor rod 1.

[0038] During operation, the external grouting device injects cement-based grout into the hollow cavity of the grouting rod 41. The grout is transported along the cavity to the spray nozzle 631 of the impeller 63 and sprayed out at high speed. The sprayed grout generates a reverse thrust, driving the impeller 63 to rotate coaxially around the axis of the grouting rod 41, thereby driving the grouting rod 41 to rotate synchronously. Since the grouting rod 41 and the fixed rod 411 are coaxially rotatably connected, and the fixed rod 411 is locked to the grouting anchor rod 1 by threads, the grouting rod 41 only rotates without axial displacement. When the grouting rod 41 rotates, the external thread on its outer wall meshes with the internal thread of the slider 64, driving the slider 64 to move axially along the inner wall of the grouting anchor rod 1. During the movement of the slider 64, the piercing needles 65 in the groove 641, under the preload of the compression spring 651, move with the slider 64, aligning one by one and inserting into each overflow hole 11, pushing out the rock chips, dust and other blockages in the hole, thus achieving hole-by-hole cleaning of the overflow holes 11. At the same time, the magnetic slider 64 moves synchronously with the sleeve 52 by magnetic attraction. The sleeve 52 drives the thread on the outer wall of the grouting anchor 1 of the fan blade 51 to rotate, so that the fan blade 51 rotates to generate airflow. Combined with the cleaning effect of the puncture needle 65, the overflow hole 11 is further cleaned, so that the grout can diffuse and fill the rock fissures through the overflow hole 11.

[0039] Example 3: Next, refer to the appendix. Figure 1-4 A method for porous compressible downhole grouting suitable for fractured rock formations, according to an embodiment of the present invention, is described, specifically including the following steps: Step S10: Smoothly lower the grouting anchor rod 1 into the pre-drilled anchor hole. Adjust the position of the grouting anchor rod 1 to align it with the center of the anchor hole axis to avoid displacement affecting the grout distribution. After the position is calibrated, tighten the anchor head fixing part 2 to the front end of the grouting anchor rod 1 so that its tapered end tightly abuts against the bottom of the anchor hole. At the same time, assemble the anchor tail fixing part 3 to the rear end of the grouting anchor rod 1 and fix it to the anchor hole opening through threaded connection to complete the installation of the grouting anchor rod 1 in the anchor hole. Step S20: Insert the hollow grouting rod 41 into the hollow cavity of the grouting anchor 1 through the through hole of the anchor tail fixing member 3 along the axial direction of the grouting anchor 1. Slowly push the grouting rod 41 so that one end of the grouting rod 41 extends to the area close to the anchor head fixing member 2. Then rotate the fixing rod 411 in the middle of the grouting rod 41. Use the external thread on the outer wall of the fixing rod 411 to engage with the internal thread on the inner wall of the grouting anchor 1 to lock the grouting rod 41 in the preset axial position to prevent displacement during grouting. Finally, extend the free end of the grouting rod 41 beyond the end of the anchor tail fixing member 3 and seal it with the external grouting device through a sealing joint. Step S30: Start the external grouting device. The cement-based grout is delivered through the inner cavity of the grouting rod 41 to the area near the anchor head fixing part 2, and flows along the hollow cavity of the grouting anchor rod 1 towards the anchor tail fixing part 3. Depending on the selected drive component, the hole cleaning and mixing operations are realized. When the driving components are float plate 61 and stirring blade 62, the continuous thrust generated by the grout flow drives float plate 61 to move towards the anchor tail along the length of grouting anchor 1. The axial movement of float plate 61 directly drives the central shaft of fan blade 51 to move synchronously, converting the axial movement into the circumferential rotation of fan blade 51. When fan blade 51 rotates, it generates airflow towards the anchor tail. The airflow covers the outer wall area of ​​grouting anchor 1 and is used to clean the rock debris, dust and impurities in overflow hole 11. When stirring blade 62 rotates, it agitates the surface of grout and improves the fluidity of surface grout. When the driving assembly consists of impeller 63, slider 64, piercing needle 65, and compression spring 651, the grout flows through the inner cavity of the grouting rod 41 to the spray nozzle 631 of the impeller 63 and is sprayed out. The sprayed grout generates a reverse thrust, driving the impeller 63 to rotate coaxially around the axis of the grouting rod 41, causing the grouting rod 41 to rotate synchronously. When the grouting rod 41 rotates, it drives the slider 64 to move axially along the inner wall of the grouting anchor rod 1. During the movement of the slider 64, the piercing needle 65 in its circumferential groove is elastically pre-tightened by the compression spring 651. Under the action of force, the push force is always maintained towards the inner wall of the grouting anchor rod 1. As the slider 64 moves, it aligns with each overflow hole 11 one by one, pushing out the rock debris and dust blocking the holes to the outside of the grouting anchor rod 1, thus completing the cleaning of each overflow hole 11. At the same time, the magnetic slider 64 attracts the ferromagnetic sleeve 52 through magnetic attraction and moves synchronously. The sleeve 52 drives the central shaft of the fan blade 51 to rotate along the thread on the outer wall of the grouting anchor rod 1, so that the fan blade 51 rotates to generate airflow, which helps to clean the overflow holes 11. Step S40: Continue grouting until the grouting pressure reaches its limit. At this point, the anchor hole and surrounding rock fissures are basically filled with grout. Continue grouting until grout is observed to overflow evenly from the inlet of the grouting rod 41, and the overflowing grout contains no air bubbles, indicating that the anchor hole and rock fissures have been completely filled with grout. At this point, close the external grouting device and keep the grouting anchor 1 fixed, allowing the grout to solidify in the anchor hole and rock fissures. After the grout has solidified, screw the sealing plug 412 into the tail of the grouting rod 41 to complete the seal. The spiral external thread 12 on the outer wall of the grouting anchor 1 forms a tight spiral interlocking structure with the solidified grout, improving the anchor's pull-out resistance and forming a stable and reliable multi-fracture rock support system.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0041] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A porous compression-type downhole grouting anchor suitable for fractured rock formations, comprising a hollow grouting anchor (1) and anchor head fixing components (2) and anchor tail fixing components (3) respectively disposed at both ends of the grouting anchor (1), wherein the grouting anchor (1) is provided with a plurality of overflow holes (11) along its length direction, characterized in that, It also includes a grouting assembly (4), which comprises: Grouting rod (41), the grouting rod (41) is a hollow grouting rod (41), the grouting rod (41) is inserted into the hollow cavity of the grouting anchor rod (1) along the axial direction of the grouting anchor rod (1), one end of the grouting rod (41) extends to the area near the anchor head fixing member (2), and the free end extends out of the end of the anchor tail fixing member (3).

2. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 1, characterized in that: The outer wall of the grouting anchor (1) is provided with a spiral external thread (12) arranged along its length direction. The overflow hole (11) passes through the spiral external thread (12) and is connected to the hollow cavity of the grouting anchor (1).

3. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 1, characterized in that: It also includes a cleaning component (5), which includes a fan blade (51) and a sleeve (52). The rotating shaft of the fan blade (51) is threadedly connected to the outer wall of the grouting anchor rod (1). The sleeve (52) is coaxially rotatably arranged with the fan blade (51). The fan blade (51) is used to clean the overflow hole (11). It also includes a driving component (6) for driving the fan blade (51) to rotate circumferentially along the length direction of the grouting anchor rod (1).

4. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 3, characterized in that: The drive assembly (6) includes a float plate (61), which is disposed between the fan blade (51) and the anchor head fixing member (2). The float plate (61) is coaxially fixedly connected to the fan blade (51). The float plate (61) cooperates with the grout, which is used to drive the float plate (61) to move along the length direction of the grouting anchor rod (1) so as to drive the fan blade (51) to rotate circumferentially along the length direction of the grouting anchor rod (1).

5. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 4, characterized in that: The floating plate (61) is coaxially fixedly connected to a stirring blade (62) at one end near the anchor head fixing member (2), and the stirring blade (62) is used to stir the slurry.

6. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 3, characterized in that: The drive assembly (6) includes an impeller (63) and a slider (64). The impeller (63) is coaxially and fixedly connected to the grout outlet of the grouting rod (41). The side wall of the rotating shaft of the impeller (63) is provided with a grout spraying nozzle (631). The grout spraying nozzle (631) is connected to the hollow cavity of the grouting rod (41). The outer wall of the grouting rod (41) is provided with an external thread. The slider (64) is threadedly connected to the outer wall of the grouting rod (41). The outer wall of the slider (64) is slidably connected to the inner wall of the grouting anchor rod (1). The sleeve (52) is a ferromagnetic sleeve (52). The slider (64) is a magnetic slider (64) used to attract the sleeve (52).

7. The porous compressible downhole grouting anchor bolt suitable for multi-fractured rock formations according to claim 6, characterized in that: The slider (64) is provided with a groove (641), and a puncture needle (65) for cleaning the overflow hole (11) is provided in the groove (641). The puncture needle (65) is connected to a compression spring (651), and the free end of the compression spring (651) is fixedly connected to the groove (641).

8. A method for porous compressible downhole grouting in fractured rock formations, comprising the application of a porous compressible downhole grouting anchor bolt as described in any one of claims 1-7, characterized in that, Includes the following steps: Step S10: Lower the grouting anchor into the anchor hole, center the grouting anchor, fix the front end of the grouting anchor with the anchor head fixing component, and fix the rear end of the grouting anchor with the anchor tail fixing component; Step S20: Insert the grouting rod into the inner cavity along the axis of the grouting anchor rod, so that one end of the grouting rod extends to the area near the anchor head fixing component, lock the axial position of the grouting rod, and then seal the free end of the grouting rod extending out of the anchor tail fixing component with the external grouting device. Step S30: Start the external grouting device. The grout is delivered to the area near the anchor head fixing part through the grouting rod and flows towards the anchor tail. The fan blade is driven by the drive component to rotate circumferentially along the length of the grouting anchor rod to clean the overflow hole and stir the grout. Step S40: When the grouting pressure reaches its limit, continue grouting until the grout overflows evenly from the liquid inlet of the grouting rod without any air bubbles. Then, close the grouting device and wait for the grout to solidify to complete the support. Finally, screw the sealing plug into the tail of the grouting rod.

9. The porous compression grouting method for multi-fractured rock formations according to claim 8, characterized in that: In step S30, the thrust generated by the slurry flow drives the float plate to move towards the anchor tail along the length of the grouting anchor rod. The float plate drives the fan blades to rotate circumferentially by driving the fan blades to move synchronously. The airflow generated is used to clean the overflow hole. At the same time, it drives the stirring blades to rotate, agitating the surface of the slurry and improving its fluidity.

10. The porous compression grouting method for multi-fractured rock formations according to claim 8, characterized in that: In step S30, the grout flows through the grouting rod to the spray nozzle of the impeller and is sprayed out, driving the impeller to rotate coaxially, which in turn drives the grouting rod to rotate, and drives the slider to move axially along the inner wall of the grouting anchor rod, so that the piercing needles are aligned one by one and inserted into each overflow hole under the pre-tightening force of the compression spring, which drives the fan blade to rotate and generate airflow to assist in cleaning the overflow holes.

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