An umbrella-shaped grouting anchor rod for supporting broken surrounding rock and a grouting reinforcement method

Abstract

The present invention discloses an umbrella-shaped grouting anchor rod and grouting reinforcement method for supporting broken surrounding rocks, which relate to the technical field of surrounding rock control in underground coal mine tunnels. The umbrella-shaped grouting anchor rod comprises a replaceable pressure transmission device, a steel hollow shell, an umbrella-shaped grouting device, and a central grouting pipe. In actual underground application scenarios, a tunnel section to be supported by grouting anchor rods is selected, drilling detection is performed, and the broken roof rock layer to be grouted is measured. Then, the umbrella-shaped grouting anchor rod is used for anchoring. Accurately differentiated grouting reinforcement is performed according to the actual crushing situation. In combination with umbrella-shaped four-directional splitting grouting, the anchoring force of the broken roof of the underground coal mine tunnel is enhanced. The spacing between the anchor rod supports is accurately controlled by the slurry diffusion distance to form a dot matrix grid grouting reinforcement group. The equipment effectively realizes targeted grouting reinforcement of the broken roof, forming a grouting network, improving the anchoring force of the anchor rod when mining under the broken roof, and improving the safety of production operations.

Description

Technical Field

[0001] The invention relates to the technical field of surrounding rock control of underground coal mine tunnels, and in particular to an umbrella-shaped grouting anchor rod for supporting broken surrounding rocks and a grouting reinforcement method. Background Art

[0002] Grouting technology has been widely used in underground engineering projects for foundation reinforcement, tunnel lining consolidation, and groundwater control. After the grouting slurry solidifies and hardens, it can act as a cementing and plugging agent, stabilizing the ground and isolating water sources to ensure smooth on-site construction. With the continuous advancement of science and technology, the application scope of this technology is becoming increasingly wider. During the excavation of underground coal mine tunnels, broken surrounding rock is often encountered. The use of traditional anchor rods and anchor cables often leads to the risk of insufficient anchoring force and water conduction through cracks in the broken surrounding rock, which can easily lead to safety accidents such as roof falls.

[0003] In order to solve the problem of poor adaptability of traditional support methods to broken surrounding rocks, coal mines currently usually use grouting reinforcement measures to reinforce the surrounding rocks of the tunnels. However, some existing grouting support equipment, such as grouting anchors and hollow grouting anchor cables, can achieve in-hole grouting and improve the integrity of the surrounding rock to a certain extent, but their grouting form is single and the targeting of different layers is poor, especially the overall control effect on large-scale water-conducting fissures is weak. For example, under the conditions of water-rich roof tunnels, existing grouting support equipment cannot effectively suspend the broken roof and play a significant water-blocking role in the aquifer above, resulting in serious safety accidents such as roof collapse and water inrush in the tunnel, which brings huge challenges to mine production. Therefore, it is urgent to invent an anchor rod that can support broken surrounding rocks with a reliable structure, strong anchoring force, and high working efficiency to provide technical support for safe and efficient tunneling construction in underground coal mine tunnels. Summary of the Invention

[0004] In response to the above problems, the present invention discloses an umbrella-shaped grouting anchor rod and a grouting reinforcement method for broken surrounding rock support. The broken roof is treated by directional grouting, and an umbrella-shaped grouting device is used to perform four-way in-hole grouting. Horizontal directional splitting grouting is formed at the end of the external bone, forming horizontal grouting diffusion, effectively realizing the targeted grouting reinforcement of the broken roof by the equipment, forming a grouting network, improving the anchoring force of the anchor rod when mining coal under the broken roof, and improving the safety of production operations.

[0005] According to the purpose of the present invention, an umbrella-shaped grouting anchor for supporting broken surrounding rocks is provided, comprising a replaceable pressure transmission device, a steel hollow shell, an umbrella-shaped grouting device and a central grouting pipe;

[0006] The replaceable pressure transmission device is arranged at the top of the steel hollow shell, and includes a top pressure-bearing plate and a middle pressure-transmitting rod; the top pressure-bearing plate is fixedly connected to one end of the middle pressure-transmitting rod and is subjected to pressure during the anchor bolt drilling process; the end of the middle pressure-transmitting rod away from the top pressure-bearing plate extends into the steel hollow shell through the pressure-transmitting rod limiting hole provided at the top of the steel hollow shell and is detachably fixedly connected to the umbrella-rib type grouting device;

[0007] The steel hollow shell is cylindrical, and has four external bone exploration holes evenly distributed along its side.

[0008] The umbrella-shaped grouting device includes a pressure-transmitting and limiting tube, a central bone and an outer probe bone; one end of the pressure-transmitting and limiting tube is detachably fixedly mounted on the middle pressure-transmitting rod and extends into one end of the hollow steel shell, and the other end is hollowly arranged; the central bone is an integrally formed component, one end of which is fixedly mounted on the top end of the central grouting tube, and the other end is inserted into the internal cavity of the pressure-transmitting and limiting tube; the outer probe bones are four and are arranged corresponding to the reserved holes of the outer probe bones, one end of each outer probe bone is rotatably connected to the pressure-transmitting and limiting tube, and the other end extends into the corresponding reserved hole of the outer probe bone, and the four outer probe bones are evenly distributed along the circumference of the pressure-transmitting and limiting tube. Cloth; a slide rail is provided on the outer probe bone, and an outer probe bone fixing guide joint is fixedly installed in the outer probe bone reserved hole, and the outer probe bone fixing guide joint is embedded in the slide rail, and the two cooperate to limit the movement trajectory of the outer probe bone; an outer probe bone injection tube is arranged on the end of the outer probe bone extending into the outer probe bone reserved hole, and the outer probe bone injection tube is connected with the central slurry delivery tube through a telescopic injection tube; the outer end of the outer probe bone extending into the outer probe bone reserved hole is also wrapped with an outer probe bone blocking liquid bag on the outside, and a blocking liquid bag pressurizing port is opened on the outer bone injection tube corresponding to the outer bone blocking liquid bag;

[0009] The central grouting pipe is fixedly installed inside the steel hollow shell through a grouting pipe fixing column, the top end is fixedly connected to the central bone, and the bottom end extends to the bottom of the anchor rod, and is provided with a bottom grouting interface; the end of the central grouting pipe connected to the central bone is connected to the external bone injection pipe through a telescopic injection pipe. After the slurry is input from the bottom grouting interface, it is input into the drill hole through the central grouting pipe, the telescopic injection pipe and the external bone injection pipe.

[0010] Preferably, the outer wall of one end of the pressure transmission limiting tube connected to the central bone is fixedly installed with an outer detection tooth of the limiting tube, and a fixed steering knuckle is fixedly installed on the outer detection tooth of the limiting tube. The outer detection bone is hinged to the outer detection tooth of the limiting tube through the fixed steering knuckle.

[0011] Preferably, one end of the central slurry delivery pipe connected to the telescopic injection pipe is provided with four outlet slurry delivery interfaces.

[0012] The present invention further discloses a method for grouting reinforcement of the umbrella-shaped grouting anchor rod for supporting broken surrounding rock, comprising the following steps:

[0013] Step 1: Select the area that needs grouting reinforcement in the underground coal mine tunnel, drill a certain number of holes in the tunnel roof, and use a rock formation detection recorder to observe and record the holes after the holes reach the predetermined depth;

[0014] Step 2: Organize and analyze the drilling process images, select the broken roof rock layer to be grouting, and determine the grouting height R ;

[0015] Step 3: According to the broken roof rock layer and grouting height found in step 2 R ,Pick R Conduct physical and mechanical parameter tests on rock samples and measure the weight of the rock γ , the tensile strength of rock σ t , Poisson's ratio of rock ν , grouting hole depth R z 、 Static lateral pressure coefficient of rock K 0;

[0016] Step 4: Calculate the vertical and horizontal splitting grouting pressures required for the grouting of the umbrella-shaped grouting anchor to form a splitting grouting vein network in the roof rock during the grouting process, based on the splitting grouting theory of rock fissures, and take the larger of the two as the minimum grouting pressure;

[0017] Step 5: Determine the actual grouting pressure based on the minimum grouting pressure determined in step 4. P z , combined with the rock grouting splitting and diffusion theory, the granular slurry splitting penetration and diffusion radius is obtained R K ;

[0018] Step 6: The granular slurry splitting penetration diffusion radius obtained in step 5 is combined with the characteristics of four-way orthogonal grouting diffusion of anchor rods to determine the spacing between anchor rods, so that a dot matrix grouting anchor rod group is formed in a certain broken roof roadway area, and the slurry is injected to form a grid-like diffusion group;

[0019] Step 7: In the area that needs grouting reinforcement, according to the location of the broken roof rock layer and the grouting height determined in step 2, R As well as the spacing between anchor rods determined in step 6, multiple lengths are constructed. L 0 anchor drilling, and grouting height in the anchor drilling R Construct horizontal grouting holes perpendicular to the anchor holes;

[0020] Step 8: Place the anchoring agent above the top bearing plate, and drill the umbrella-shaped grouting anchor into the anchor hole using an anchor drill. When the anchor reaches the head of the anchor hole, pierce the anchoring agent to form an anchor end.

[0021] Step 9: Continue to apply drilling force to the umbrella-shaped grouting anchor bolt. The top pressure plate, the middle pressure transmission rod and the pressure transmission limit tube remain in position. The steel hollow shell and the center bone continue to move into the anchor bolt borehole. At this time, the center bone is inserted into the internal cavity of the pressure transmission limit tube. At the same time, the outer bones are expanded upward and outward and inserted into the horizontal grouting hole. When the outer bones are expanded to a horizontal state, the center bone is just inserted into the top of the pressure transmission limit tube for mechanical locking, and the drilling action stops.

[0022] Step 10: Based on the actual grouting pressure determined in step 5, use a high-pressure grouting pump to perform grouting through the lower grouting interface at the tail end of the umbrella-shaped grouting anchor rod.

[0023] Preferably, in step 4, the vertical splitting grouting pressure and horizontal splitting grouting pressure required for the umbrella-shaped grouting anchor to form a splitting grouting vein network in the roof rock during the grouting process are calculated as follows:

[0024] Vertical cleavage:

[0025]

[0026] Horizontal splitting:

[0027]

[0028] Where:

[0029] P 0-grouting pressure, kPa;

[0030] γ - rock density, kN / m3;

[0031] R z - Grouting hole depth, m;

[0032] σ t - tensile strength of rock, kPa;

[0033] N -The proportional coefficient of the fluid pressure used to expand the pore wall, which generally varies between 0 and 1;

[0034] ν - Poisson's ratio of the rock;

[0035] K 0-static lateral pressure coefficient of rock.

[0036] Preferably, in step 5, the granular slurry splitting penetration diffusion radius R K The calculation method is:

[0037]

[0038] Where:

[0039] ρ w -Density of water, g / cm 3 ;

[0040] g - Gravitational acceleration, cm / s 2 ;

[0041] P z -actual grouting pressure, kPa;

[0042] r e -Equivalent radius of the pore, cm;

[0043] S - Gel strength of grouting material, dyn / cm²;

[0044] R z - Depth of grouting holes, m.

[0045] Compared with the prior art, the advantages of the umbrella-shaped grouting anchor and grouting reinforcement method for supporting broken surrounding rocks disclosed in the present invention are:

[0046] (1) The present invention is used for supporting the broken roof in the well. Its umbrella-shaped grouting device can be fixed by mechanical locking through the cooperation of the pressure-transmitting limit tube and the central bone. Its umbrella-shaped movement shape can ensure that the outer bone can be extended in a smaller space, so that the reserved hole has no squeezing and hindering effect on the outer bone. At the same time, its mechanical locking structure can make the outer bone at an angle of 90° with the anchor rod body when it is opened, so that the anchoring force of the anchor rod can be increased through the mechanical structure.

[0047] (2) The present invention treats the broken roof through directional grouting, uses an umbrella-shaped grouting device to perform four-way in-hole grouting, forms horizontal directional splitting grouting at the end of the external probe, and forms horizontal grouting diffusion. Compared with the spherical and columnar grouting of traditional grouting equipment, this equipment does not use the grouting anchor as a grouting unit to perform grouting in a very small range, but forms a dot matrix grouting grid through the four-way horizontal diffusion of the slurry, which can effectively prevent the roof from falling and water seepage.

[0048] (3) The dot matrix installation scheme provided by the present invention can pressurize the equipment through the minimum horizontal and vertical splitting pressure of the rock, and determine the spacing between the anchor equipment through the slurry diffusion radius. It is used for safe and efficient operations under a large range of broken roofs. Within a certain range, the equipment can be used at intervals to form a grouting grid plate model in a large range of roof fracture zones, which can provide a grid-type water-blocking layer for production activities under the aquifer. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 This is a schematic diagram of the overall device of the umbrella-shaped grouting anchor.

[0051] Figure 2 This is a schematic diagram of the external bone exploration.

[0052] Figure 3 Schematic diagram of the umbrella rib grouting device.

[0053] Figure 4 Expand the top view for the external bone.

[0054] Figure 5 This is a top view of the center slurry pipe.

[0055] Figure 6 This is the effect diagram of using a single umbrella-rib type grouting anchor.

[0056] Figure 7 Use the renderings for the anchor group.

[0057] In the figure: 1-replaceable pressure transmission device; 11-top pressure plate; 12-middle pressure transmission rod; 2-steel hollow shell; 21-pressure transmission rod limiting hole; 22-external probe bone reserved hole; 221-external probe bone fixed guide joint; 3-umbrella rib type grouting device; 31-pressure transmission limiting tube; 311-external probe tooth of limiting tube; 312-fixed steering knuckle; 32-center bone; 33-external probe bone; 331-slide rail; 332-external probe bone injection tube; 333-sealing liquid sac pressure port; 334-external probe bone sealing liquid sac; 335-liquid outlet; 4-center slurry pipe; 41-four-outlet slurry interface; 42-telescopic injection pipe; 43-lower slurry interface; 5-slurry pipe fixing column; 6-high-pressure grouting pump. DETAILED DESCRIPTION

[0058] The following is a brief description of the specific embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are also within the scope of protection of the present invention.

[0059] Figure 1-Figure 7 The preferred embodiments of the present invention are shown and analyzed in detail.

[0060] like Figure 1 、 2 , 4 is an umbrella-shaped grouting anchor for crushed surrounding rock support, comprising a replaceable pressure transmission device 1, a steel hollow shell 2, an umbrella-shaped grouting device 3 and a central grouting pipe 4.

[0061] The replaceable pressure transmission device 1 is arranged at the top of the steel hollow shell 2, and includes a top pressure plate 11 and a middle pressure transmission rod 12. The top pressure plate 11 is a metal flat plate, and the middle pressure transmission rod 12 is a rigid metal rod. The top pressure plate 11 is fixedly connected to one end of the middle pressure transmission rod 12 and is subjected to pressure during the process of anchor drilling. The end of the middle pressure transmission rod 12 away from the top pressure plate 11 extends into the steel hollow shell 2 through the pressure transmission rod limiting hole 21 set at the top of the steel hollow shell 2 and is threadedly connected to the umbrella-shaped grouting device 3. During the process of anchor drilling into the hole, as the anchor is drilled, the pressure on the top gradually increases, and the top pressure plate 11 transmits the pressure directly downward through the middle pressure transmission rod 12. Since the direction of the force transmitted by the top pressure plate 11 may not be along the drilling direction, the device fails. In order to avoid this situation, a pressure transmission rod limiting hole 21 is provided to constrain the longitudinal force direction of the middle pressure transmission rod 12.

[0062] The hollow steel shell 2 is cylindrical in shape, with four holes 22 evenly distributed around its circumference for external probing. A pressure-transmitting rod stopper hole 21, slightly larger than the outer diameter of the central pressure-transmitting rod 12, is located at the top of the hollow steel shell 2, limiting its horizontal displacement and ensuring only vertical displacement. The top pressure-bearing plate 11 is a horizontal metal plate parallel to the upper surface of the steel shell.

[0063] like Figure 3The umbrella-shaped grouting device 3 shown includes a pressure-transmitting and limiting tube 31, a central bone 32, and an outer probe bone 33. One end of the pressure-transmitting and limiting tube 31 is threadedly connected to one end of the middle pressure-transmitting rod 12 extending into the hollow steel shell 2, and the other end is a hollow metal straight tube with a closed upper end and an open lower end. The central bone 32 is an integrally formed component, one end of which is welded to the top of the central grouting pipe 4, and the other end is inserted into the internal cavity of the pressure-transmitting and limiting tube 31. The inner diameter of the pressure-transmitting and limiting tube 31 is slightly larger than the outer diameter of the central bone 32. There are four outer probe bones 33 corresponding to the outer probe bone reserved holes 22, and the four outer probe bones 33 are evenly distributed along the circumference of the pressure-transmitting and limiting tube 31. One end of each outer probe bone 33 is rotatably connected to the pressure-transmitting and limiting tube 31, and the other end extends into the corresponding outer probe bone reserved hole 22. Specifically, four outer probing teeth 311 are fixedly mounted circumferentially on the outer wall of one end of the pressure-transmitting limiting tube 31 connected to the central bone 32. The outer probing teeth 311 are integrally formed components fixed to the tail end of the pressure-transmitting limiting tube 31. A fixed steering knuckle 312 is fixedly mounted on the outer probing teeth 311, and the outer probing bone 33 is hingedly connected to the outer probing teeth 311 via the fixed steering knuckle 312. A slide rail 331 is provided on the outer probing bone 33, and an outer probing bone fixed guide joint 221 is fixedly mounted in the outer probing bone reserved hole 22. The outer probing bone fixed guide joint 221 is embedded in the slide rail 331. The two cooperate to limit the motion trajectory of the outer probing bone 33, ensuring that the motion of the outer probing bone 33 is completely within the reserved range of the outer probing bone reserved hole 22. An external bone injection tube 332 is arranged on one end of the external bone 33 extending into the external bone reserved hole 22. The external bone injection tube 332 is connected to the central grouting tube 4 through a telescopic injection tube 42, and the other end is a liquid outlet 335. The external end of the external bone 33 extending into the external bone reserved hole 22 is also wrapped with an external bone blocking liquid sac 334. A blocking liquid sac pressurization port 333 is opened on the external bone injection tube 332 corresponding to the external bone blocking liquid sac 334. When the slurry in the device is pressurized, the external bone blocking liquid sac 334 is pressurized by the blocking liquid sac pressurization port 333 to block the horizontal grouting hole.

[0064] When the outer rib 33 is deployed, the fixed steering knuckle 312 causes the end of the outer rib 33 within the hollow steel shell 2 to exhibit a tendency to move vertically downward. Meanwhile, the middle portion of the outer rib 33, restrained by the outer rib fixed guide knuckle 221, causes the end of the outer rib 33 outside the hollow steel shell 2, i.e., the end at the liquid outlet 335, to exhibit a tendency to simultaneously rotate upward and extend outward. When the center rib 32 reaches the upper wall of the pressure transmission and limiting tube 31, the outer rib 33's outward extension is complete, at which point the angle between the outer rib 33 and the outer wall of the hollow steel shell 2 is 90°. At this point, the umbrella-shaped grouting device 3 is fully deployed, forming a mechanical lock.

[0065] The central slurry pipe 4 is fixedly installed inside the steel hollow shell 2 through the slurry pipe fixing column 5. The top end is welded to the central bone 32, and the bottom end extends to the bottom of the anchor rod, and is provided with a bottom slurry interface. The end of the central slurry pipe 4 connected to the central bone 32 is provided with four outlet slurry interfaces 41, such as Figure 5 As shown, the four-outlet grouting interface 41 is connected to the external bone injection tube 332 through a telescopic injection tube 42. The lower grouting pump presses the slurry into the bottom grouting interface, along the central grouting tube 4 to the four-outlet grouting interface 41, and then through the telescopic injection tube 42 and the external bone injection tube 332 into the horizontal expansion borehole.

[0066] like Figure 6 、 7 As shown, the present invention further discloses a method for grouting reinforcement of the umbrella-shaped grouting anchor rod for broken surrounding rock support, comprising the following steps:

[0067] Step 1: Select the area that needs grouting reinforcement in the underground coal mine tunnel according to the production conditions, and drill a certain number of peepholes directly above the tunnel roof, symmetrically above and on both sides of the tunnel. After the drilling reaches the predetermined depth, place the rock formation detection recorder deep into the peephole to record important information during the observation process, including cracks, broken zones and rock property changes in the surrounding rock, and take videos or photos.

[0068] Step 2: Organize and analyze the images of the drilling process, record the distance between the broken roof rock layer that needs to be grouting in the collected video, and record its distance from the inner wall of the tunnel roof as R , the equivalent radius of the pores in the fracture area is recorded as r e , finally determine the grouting height R .

[0069] Step 3: According to the broken roof rock layer and grouting height found in step 2 R ,Pick R Conduct physical and mechanical parameter tests on rock samples and measure the weight of the rock γ , the tensile strength of rock σ t , Poisson's ratio of rock ν , grouting hole depth R z 、 Static lateral pressure coefficient of rock K 0.

[0070] Step 4: Calculate the vertical and horizontal splitting grouting pressures required for the grouting of the umbrella-shaped grouting anchor to form a splitting grouting vein network in the roof rock during the grouting process, based on the splitting grouting theory of rock fissures, and take the larger of the two as the minimum grouting pressure;

[0071] Vertical cleavage:

[0072]

[0073] Horizontal splitting:

[0074]

[0075] Where:

[0076] P 0-grouting pressure, kPa;

[0077] γ - rock density, kN / m3;

[0078] R z - Grouting hole depth, m;

[0079] σ t - tensile strength of rock, kPa;

[0080] N -The proportional coefficient of the fluid pressure used to expand the pore wall, which generally varies between 0 and 1;

[0081] ν - Poisson's ratio of the rock;

[0082] K 0-static lateral pressure coefficient of rock.

[0083] Step 5: Determine the actual grouting pressure based on the minimum grouting pressure determined in step 4. P z , combined with the rock grouting splitting and diffusion theory, the granular slurry splitting penetration and diffusion radius is obtained R K ;

[0084] Splitting penetration and diffusion radius of granular slurry R K The calculation method is:

[0085]

[0086] Where:

[0087] ρ w - Density of water, g / cm 3 ;

[0088] g - Gravitational acceleration, cm / s 2 ;

[0089] P z -actual grouting pressure, kPa;

[0090] r e -Equivalent radius of the pore, cm;

[0091] S - Gel strength of grouting material, dyn / cm²;

[0092] R z - Depth of grouting holes, m.

[0093] Step 6: Combine the granular slurry splitting penetration diffusion radius obtained in step 5 with the characteristics of four-way orthogonal grouting diffusion of anchor rods to determine the spacing between anchor rods, so that a dot matrix grouting anchor rod group is formed in a certain broken roof tunnel area, and the slurry is injected to form a grid-like diffusion group.

[0094] Step 7: In the area that needs grouting reinforcement, according to the location of the broken roof rock layer and the grouting height determined in step 2, R As well as the spacing between anchor rods determined in step 6, multiple lengths are constructed. L 0 anchor drilling, and grouting height in the anchor drilling R Directional drilling horizontal expansion PDC drill bits are used to construct horizontal grouting holes perpendicular to the anchor holes, so that the upper area of ​​the anchor holes has lateral horizontal four-way orthogonal expansion holes. Specifically, the length of the anchor hole L 0 equals grouting height R Add the length of the top pressure plate 11, the middle pressure-transmitting rod 12, and the pressure-transmitting stopper 31 of the umbrella-shaped grouting anchor. The diameter of the horizontal grouting hole is determined by the maximum outer diameter of the pressurized outer probing sac 334. It is required to be no larger than the maximum outer diameter of the pressurized outer probing sac 334 to ensure a good sealing effect while not affecting the deployment of the outer probing sac 33. The depth of the grouting hole is required to be slightly longer than the length of the outer probing sac 33 to ensure that the outer probing sac 33 can be deployed horizontally.

[0095] Step eight: place the anchoring agent above the top pressure plate 11, drill the umbrella-shaped grouting anchor into the anchor hole through the anchor drilling machine, and pierce the anchoring agent when the anchor reaches the anchor hole head to form an anchor end.

[0096] Step nine, continue to apply drilling force to the umbrella-shaped grouting anchor rod, the top pressure plate 11, the middle pressure transmission rod 12 and the pressure transmission limit tube 31 remain in position, the steel hollow shell 2 together with the center bone 32 continue to move into the anchor rod borehole, at this time the center bone 32 is inserted into the internal cavity of the pressure transmission limit tube 31, and at the same time the outer bone 33 is expanded upward and outward and inserted into the horizontal grouting hole. When the outer bone 33 is expanded to a horizontal state, the center bone 32 is also inserted into the top of the pressure transmission limit tube 31 for mechanical locking, and the drilling action stops.

[0097] Step 10: Based on the actual grouting pressure determined in step 5, use the high-pressure grouting pump 6 to perform grouting through the lower grouting interface 43 at the tail end of the umbrella-shaped grouting anchor rod.

[0098] The above description of the disclosed embodiments will enable one skilled in the art to implement and use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. An umbrella-shaped grouting anchor for supporting broken surrounding rocks, characterized in that: It comprises a replaceable pressure transmission device (1), a steel hollow shell (2), an umbrella-shaped grouting device (3), and a central grouting pipe (4); The replaceable pressure transmission device (1) is arranged at the top of the steel hollow shell (2), and includes a top pressure-bearing plate (11) and a middle pressure-transmitting rod (12); the top pressure-bearing plate (11) is fixedly connected to one end of the middle pressure-transmitting rod (12), and is subjected to pressure during the process of anchor drilling; the end of the middle pressure-transmitting rod (12) away from the top pressure-bearing plate (11) extends into the steel hollow shell (2) through the pressure-transmitting rod limiting hole (21) provided at the top of the steel hollow shell (2) and is detachably fixedly connected to the umbrella-shaped grouting device (3); The steel hollow shell (2) is cylindrical, and has four external bone exploration holes (22) evenly distributed along its side. The umbrella-shaped grouting device (3) comprises a pressure-transmitting and limiting tube (31), a central bone (32) and an outer bone (33); one end of the pressure-transmitting and limiting tube (31) is detachably fixedly mounted on one end of the middle pressure-transmitting rod (12) extending into the steel hollow shell (2), and the other end is hollowly arranged; the central bone (32) is an integrally formed component, one end of which is fixedly mounted on the top end of the central slurry delivery pipe (4), and the other end is inserted into the inner cavity of the pressure-transmitting and limiting tube (31); the outer bones (33) are four and are arranged corresponding to the outer bone reserved holes (22), one end of each outer bone (33) is rotatably connected to the pressure-transmitting and limiting tube (31), and the other end extends into the corresponding outer bone reserved hole (22), and the four outer bones (33) are evenly distributed along the circumference of the pressure-transmitting and limiting tube (31); the outer bones (33) are arranged in a uniform manner ... ) is provided with a slide rail (331), an outer bone fixing guide section (221) is fixedly installed in the outer bone reserved hole (22), and the outer bone fixing guide section (221) is embedded in the slide rail (331), and the two cooperate to limit the movement trajectory of the outer bone (33); an outer bone injection tube (332) is arranged on one end of the outer bone (33) extending into the outer bone reserved hole (22), and the outer bone injection tube (332) is connected to the central slurry delivery tube (4) through a telescopic injection tube (42); the outer end of the outer bone (33) extending into the outer bone reserved hole (22) is also wrapped with an outer bone blocking liquid sac (334), and a blocking liquid sac pressurizing port (333) is opened on the outer bone injection tube (332) corresponding to the outer bone blocking liquid sac (334); The central grouting pipe (4) is fixedly installed inside the steel hollow shell (2) through a grouting pipe fixing column (5), the top end of which is fixedly connected to the central bone (32), and the bottom end of which extends to the bottom of the anchor rod and is provided with a bottom grouting interface; one end of the central grouting pipe (4) connected to the central bone (32) is communicated with the external bone injection pipe (332) through a telescopic injection pipe (42); after the slurry is input through the bottom grouting interface, it is input into the drill hole through the central grouting pipe (4), the telescopic injection pipe (42) and the external bone injection pipe (332).

2. The umbrella-shaped grouting anchor for supporting broken surrounding rocks according to claim 1, characterized in that: The outer wall of one end of the pressure transmission limiting tube (31) connected to the central bone (32) is fixedly mounted with a limiting tube outer probing tooth (311), a fixed steering knuckle (312) is fixedly mounted on the limiting tube outer probing tooth (311), and the outer probing bone (33) is hinged to the limiting tube outer probing tooth (311) via the fixed steering knuckle (312).

3. The umbrella-shaped grouting anchor for supporting broken surrounding rocks according to claim 1, characterized in that: One end of the central slurry delivery pipe (4) connected to the telescopic liquid injection pipe (42) is provided with four outlet slurry delivery interfaces (41).

4. A method for grouting reinforcement using the umbrella-shaped grouting anchor for broken surrounding rock support according to claim 1, characterized in that: The following steps are involved: Step 1: Select the area that needs grouting reinforcement in the underground coal mine tunnel, drill a certain number of holes in the tunnel roof, and use a rock formation detection recorder to observe and record the holes after the holes reach the predetermined depth; Step 2: Organize and analyze the drilling process images, select the broken roof rock layer to be grouting, and determine the grouting height R ; Step 3: According to the broken roof rock layer and grouting height found in step 2 R ,Pick R Conduct physical and mechanical parameter tests on rock samples and measure the weight of the rock γ , the tensile strength of rock σ t , Poisson's ratio of rock ν , grouting hole depth R z 、 Static lateral pressure coefficient of rock K 0; Step 4: Calculate the vertical and horizontal splitting grouting pressures required for the grouting of the umbrella-shaped grouting anchor to form a splitting grouting vein network in the roof rock during the grouting process, based on the splitting grouting theory of rock fissures, and take the larger of the two as the minimum grouting pressure; Step 5: Determine the actual grouting pressure based on the minimum grouting pressure determined in step 4. P z , combined with the rock grouting splitting and diffusion theory, the granular slurry splitting penetration and diffusion radius is obtained R K ; Step 6: The granular slurry splitting penetration diffusion radius obtained in step 5 is combined with the characteristics of four-way orthogonal grouting diffusion of anchor rods to determine the spacing between anchor rods, so that a dot matrix grouting anchor rod group is formed in a certain broken roof roadway area, and the slurry is injected to form a grid-like diffusion group; Step 7: In the area that needs grouting reinforcement, according to the location of the broken roof rock layer and the grouting height determined in step 2, R As well as the spacing between anchor rods determined in step 6, multiple lengths are constructed. L 0 anchor drilling, and grouting height in the anchor drilling R Construct horizontal grouting holes perpendicular to the anchor holes; Step 8: Place the anchoring agent above the top bearing plate (11), and drill the umbrella-shaped grouting anchor into the anchor hole using an anchor drilling machine. When the anchor reaches the head of the anchor hole, pierce the anchoring agent to form an anchoring end. Step nine, continue to apply drilling force to the umbrella-shaped grouting anchor rod, the top pressure plate (11), the middle pressure transmission rod (12) and the pressure transmission limit tube (31) remain in position, the steel hollow shell (2) together with the center bone (32) continue to move into the anchor rod borehole, at this time the center bone (32) is inserted into the internal cavity of the pressure transmission limit tube (31), and at the same time the outer bone (33) is expanded upward and outward to be inserted into the horizontal grouting hole, and when the outer bone (33) is expanded to a horizontal state, the center bone (32) is also just inserted into the top of the pressure transmission limit tube (31) for mechanical locking, and the drilling action is stopped; Step 10: Based on the actual grouting pressure determined in step 5, a high-pressure grouting pump (6) is used to perform grouting through the lower grouting interface (43) at the tail end of the umbrella-shaped grouting anchor rod.

5. The method according to claim 4, characterized in that In step 4, the vertical splitting grouting pressure and horizontal splitting grouting pressure required for the grouting of the umbrella-shaped grouting anchor to form a splitting grouting vein network in the roof rock layer during the grouting process are calculated as follows: Vertical cleavage: Horizontal splitting: Where: P 0-grouting pressure, kPa; γ - Rock density, kN / m 3 ; R z - Grouting hole depth, m; σ t - tensile strength of rock, kPa; N -The proportional coefficient of the fluid pressure used to expand the pore wall, which generally varies between 0 and 1; ν - Poisson's ratio of the rock; K 0-static lateral pressure coefficient of rock.

6. The method according to claim 5, characterized in that In step 5, the granular slurry splitting penetration diffusion radius R K The calculation method is: Where: ρ w -Density of water, g / cm 3 ; g - Gravitational acceleration, cm / s 2 ; P z -actual grouting pressure, kPa; r e -Equivalent radius of the pore, cm; S - Gel strength of grouting material, dyn / cm²; R z - Depth of grouting holes, m.

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