High-pressure grouting end anchor type self-drilling prestressed anchor rod and construction method thereof

Abstract

The application discloses a high-pressure grouting end anchor type self-drilling prestressed anchor rod, which comprises a drill bit, anchoring material, a hollow rod body, a grouting controller and a grouting mixer, the drill bit is connected to the end of the anchoring section of the hollow rod body, the grouting controller is installed on the hollow rod body, the two ends of the grouting controller are connected with the hollow rod body respectively, the grouting mixer is communicated with the end of the free end of the hollow rod body, the hollow rod body is internally provided with a grouting channel, the anchoring material is stirred uniformly in the grouting mixer, and the anchoring material is injected through the grouting channel of the hollow rod body. The high-pressure grouting end anchor type self-drilling prestressed anchor rod has high anchoring force and good timeliness, the setting of the grouting controller ensures that the anchoring material is grouted densely and uniformly wrapped around the rod body, so that the anchoring force is greatly improved; the problems of the prior art, such as the incomplete grouting, the incompact grouting, the poor adhesion with the hole wall and the like, are solved, and the problems of low anchoring force, poor timeliness and inability to immediately apply prestress are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tunnel engineering, and particularly relates to a high-pressure grouting end anchor type self-drilling prestressed anchor rod and a construction method thereof. BACKGROUND

[0002] When the anchor rod is applied in soft and loose surrounding rock stratum, the borehole of the surrounding rock is easy to collapse, and the self-advancing anchor rod is often used.

[0003] Firstly, because of the poor integrity of the hole wall, the low strength of the surrounding rock, and the slow solidification of the cement-based anchoring material matched with the self-advancing anchor rod, there are problems such as incomplete and non-dense grouting of the anchoring section, poor adhesion with the hole wall, and the like, which leads to low anchoring force, poor time efficiency, and inability to immediately apply prestress.

[0004] Secondly, the traditional anchor rod applies prestress by means of tightening the nut to extrude the gasket, when the nut or the thread processing precision of the rod body is not high and the gasket is inclined, the nut is self-locked due to eccentric force, which makes it difficult to be tightened, and further causes the gasket to be unable to be extruded to apply prestress or the error condition that the prestress is considered to be applied in place.

[0005] Finally, the tunnel in soft and loose stratum is easy to deform greatly, and the anchor rod locally fails, and because the connection between the anchor rods is weak, the anchor rods cannot bear force cooperatively, and further develop to overall failure.

[0006] In summary, the existing anchor rod is difficult to meet the needs of instant support, strong support and overall support of the soft surrounding rock tunnel.

[0007] Through retrieval, it is found that the Chinese utility model patent with the patent number CN201820737228 disclosed on February 19, 2019 discloses a grouting anchoring self-drilling prestressed anchor rod device for soft rock roadway, which comprises a nut tray, a tail rod body and an end steel pipe rod body, the tail rod body is connected with the nut tray, and a grouting hole is arranged in the middle; the end steel pipe rod body is provided with an overflow hole and a conical tip; a rod thread connection section is arranged between the tail rod body and the end steel pipe rod body; an anchor rod thread section is arranged between the nut tray and the tail rod body; and an anchor rod anchoring section is arranged on the end steel pipe rod body. However, the above technical problems cannot be solved. SUMMARY

[0008] In view of the deficiencies in the prior art, the purpose of the present application is to provide a high-pressure grouting end anchor type self-drilling prestressed anchor rod which is simple in structure and convenient to use, has high anchoring force and good time efficiency, and the setting of the grouting controller ensures that the anchoring material is grouted densely and uniformly wrapped around the rod body, thereby greatly improving the anchoring force; and a construction method of the high-pressure grouting end anchor type self-drilling prestressed anchor rod.

[0009] In order to achieve the above object, the technical scheme of the present application is as follows: a high-pressure grouting end anchor type self-drilling prestressed anchor rod, comprising a drill bit, anchoring material, a hollow rod body, a grouting controller and a grouting mixer, the drill bit is connected to the end of the anchoring section of the hollow rod body, the grouting controller is installed on the hollow rod body, the two ends of the grouting controller are connected with the hollow rod body respectively, the grouting mixer is communicated with the end of the free end of the hollow rod body, the hollow rod body is internally provided with a grouting channel, the anchoring material is stirred uniformly in the grouting mixer, and the anchoring material is injected through the grouting channel of the hollow rod body.

[0010] Further, the anchoring material is A and B two-component material, which is mixed in a certain proportion, after the anchoring material overflows from the drill bit, high-pressure grouting is carried out in the closed space of the anchoring section and penetrates into the hole wall fracture, and the anchoring material can be solidified within 30-120 seconds to quickly anchor the end of the anchor rod.

[0011] Further, the hollow rod body is made of high-elongation steel material, the outer surface of the rod body of the hollow rod body is provided with left-handed or right-handed standard wave-shaped threads, and the inside of the hollow rod body is a hollow structure as the grouting channel.

[0012] Further, the grouting controller comprises a hollow core pipe and a shell, the two ends of the hollow core pipe are connected with the hollow rod body through standard wave-shaped internal threads respectively, the shell is wrapped outside the hollow core pipe, and the two ends of the shell and the hollow core pipe are sealingly connected through a metal fastening ring.

[0013] Further, a closed space is formed between the outer wall of the hollow core pipe and the inner wall of the shell, water-absorbing material is preinstalled in the closed space, and the middle part of the hollow core pipe is provided with symmetrically distributed one-way valve grout holes.

[0014] Further, the grouting controller connects two hollow rod bodies to jointly form a grouting channel, when grouting, grout flows from the one-way valve grout holes on the hollow core pipe to the shell, the shell expands to completely block the drill hole, a closed space is formed in the anchoring section, and the anchor rod is centered in the drill hole after the grouting controller expands.

[0015] Further, the anchor rod further comprises a limiting pad, the limiting pad is a conical pad, a circle of retreat-stopping teeth is arranged at the central hole of the limiting pad, the retreat-stopping teeth are tightly engaged with the wave-shaped threads on the outer surface of the hollow rod body, and the limiting pad can only advance on the hollow rod body and cannot retreat.

[0016] Further, one corner of the limiting pad is raised and provided with a through hole, high-strength steel wires pass through the through holes of the plurality of limiting pads in sequence to connect the plurality of anchor rods to form an integral force bearing.

[0017] Further, the anchor rod further comprises a grout-stopping plug, the grout-stopping plug is arranged at the free end of the hollow rod body and located in front of the limiting pad.

[0018] The application also relates to a construction method of a high-pressure grouting end anchor type self-drilling prestressed anchor rod.

[0019] Step 1. Construction preparation: preparing anchor rod drills, grouting systems, rod bodies and accessories, anchoring materials, high-pressure air / water working conditions required for anchor rod construction;

[0020] Step 2. Drilling and hole cleaning: connecting the assembled anchor rod to the anchor rod drill, starting the drill to drive the rod body to rotate, and the drill bit cuts the surrounding rock to drill a hole. When the designed depth is reached, connect the high-pressure air / water pipe and clean the hole through high-pressure air / water;

[0021] Step 3. First, apply axial force to the anchor rod so that the anchor rod drill bit rests on the hole bottom surrounding rock; second, according to the type of grouting controller, different ways are taken to make the shell of the grouting controller expand to block the hole;

[0022] Step 4. End anchor high-pressure grouting: the two feed pipes of the high-pressure grouting pump are respectively placed in the two storage tanks for storing the A and B components of the anchoring material, and the grouting pipe is connected to the hollow rod body for high-pressure grouting;

[0023] Step 5. Prestress application: install the limiting pad plate on the rod body, use the anchor rod installation tool to tension the hollow rod body, and continuously push the limiting pad plate to press the surrounding rock surface, when the tensioning force reaches the requirement, loosen the hollow rod body, and install the nut behind the limiting pad plate;

[0024] Step 6. After all the anchor rods are installed, use high-strength steel wire to connect the limiting pad plates at the key positions of the anchor rods into a net;

[0025] Step 7. Anchor rod post-grouting: when further protection of the anchor rod is required, a small hole reserved on the limiting pad plate and the grouting pipe can be inserted into the hole to grout the cement slurry at the free end of the hollow anchor rod.

[0026] The advantages of the technical scheme of the application are as follows:

[0027] 1、The grouting controller of the application can ensure the grouting of anchoring material to be compact and uniformly wrapped around the rod body without affecting the anchoring rod drilling, hole cleaning and stress, thereby greatly improving the anchoring force. Specifically as follows: ① the grouting controller can connect two hollow rod bodies together to form a grouting channel, effectively transfer the anchoring rod tension, and does not affect the anchoring rod drilling, hole cleaning and hole cleaning; ② the grouting controller can be expanded at the initial stage of grouting to completely block the drilling hole and form a closed space in the anchoring section, thereby preventing the anchoring material from flowing, saving material, and enabling high-pressure grouting of the anchoring section to improve the grouting fullness and compactness; ③ the expanded grouting controller can center the anchoring rod in the drilling hole, avoiding the problem of insufficient annular thickness of the anchoring material when the rod body contacts the hole wall; ④ when installing the anchoring rod at the top of the tunnel, the expanded grouting controller can temporarily fix the anchoring rod in the drilling hole, and the anchoring rod will not slip out or fall, avoiding the need for additional manual or mechanical temporary support during construction.

[0028] 2、The high-pressure grouting end anchor type self-drilling prestressed anchor rod of the application uses A and B two-component anchoring material, which can solidify within 30-120 seconds, thereby realizing rapid anchoring of the end of the anchor rod; the limiting pad plate has a retreat stopping tooth, and the hollow rod body can only advance and cannot retreat. Therefore, during construction, the limiting pad plate is only needed to be placed against the surrounding rock surface and the hollow rod body is pulled outward, so that the prestress can be applied, and the operation is simple and the prestress value is clear; the high-strength steel wire strand connects multiple anchor rods to form a cooperative force structure, avoiding the failure of the overall group anchor support caused by the failure of the local anchor rod. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a schematic diagram of the high-pressure grouting end anchor type self-drilling prestressed anchor rod of the application before grouting and anchoring;

[0030] Figure 2 It is a schematic diagram of the high-pressure grouting end anchor type self-drilling prestressed anchor rod of the application after grouting and anchoring;

[0031] Figure 3 It is a schematic diagram of the structure of the grouting controller before expansion;

[0032] Figure 4 It is a schematic diagram of the structure of the grouting controller after expansion;

[0033] Figure 5 It is a schematic diagram of the installation of the grouting plug on the anchor rod;

[0034] Figure 6 It is a schematic diagram of the installation structure of the limiting pad plate;

[0035] Figure 7 It is a schematic diagram of the connection of multiple anchor rods together.

[0036] In the figure: 1, drill bit; 2, anchoring material; 3, hollow rod body; 4, grouting controller; 41, hollow core tube; 42, outer shell; 43, metal fastening ring; 44, closed space; 45, one-way valve grout hole; 5, corrosion-proof sleeve; 6, connecting sleeve; 7, grout stopper; 8, limiting pad; 81, retreat stopper; 82, through hole; 9, nut; 10, high-strength steel wire; 11, grouting mixer. DETAILED DESCRIPTION

[0037] In the present application, it is understood that the terms "length"; "width"; "upper"; "lower"; "front"; "rear"; "left"; "right"; "vertical"; "horizontal"; "top"; "bottom"; "inner"; "outer"; "clockwise"; "counterclockwise"; "axial"; "planar direction"; "circumferential direction" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation; be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0038] As Figure 1 shown, a high-pressure grouting end anchor type self-drilling prestressed anchor rod, comprising a drill bit 1, an anchoring material 2, a hollow rod body 3, a grouting controller 4 and a grouting mixer 11, the drill bit 1 is connected at the end of the anchoring segment of the hollow rod body 3, the grouting controller 4 is installed on the hollow rod body 3, the two ends of the grouting controller 4 are connected with the hollow rod body 3 respectively, the grouting mixer 11 is in communication with the end of the free end of the hollow rod body 3, the hollow rod body 3 is provided with a grouting channel inside, the anchoring material 2 is stirred evenly in the grouting mixer 11, and the anchoring material 2 is injected through the grouting channel of the hollow rod body 3. The high-pressure grouting end anchor type self-drilling prestressed anchor rod of the present application has high anchoring force and good time effectiveness, the setting of the grouting controller ensures that the anchoring material grouts densely and uniformly wraps the rod body, thereby greatly improving the anchoring force; solves the problems of unsatisfied grouting, poor density, poor adhesion with the hole wall and the like in the prior art, and the problems of low anchoring force, poor time effectiveness and inability to immediately apply prestress.

[0039] The drill bit 1 is a disposable drill bit, and the main function is to cut the surrounding rock to form a hole; the drill bit has a small hole, through which high-pressure air and high-pressure water can be blown to remove slag and clean the hole, and grout can also be discharged.

[0040] The anchoring material 2 is a two-component material A and B, which is mixed in a certain proportion, the anchoring material 2 is overflowed from the drill bit 1, high-pressure grouting is carried out in the closed space of the anchoring segment, and penetration into the hole wall fissure is carried out, the anchoring material 2 can be solidified within 30-120 seconds to quickly anchor the end of the anchor rod.

[0041] The anchoring material is preferably a silicate modified polyurethane grouting material, which comprises two components, commonly known as black material and white material. The A component is composed of polyether polyol, sodium silicate, catalyst, flame retardant, antistatic agent and other components, and the B component is composed of polymethylene polyphenyl polyisocyanate, polymeric MDI, thixotropic agent and other components. The mixing ratio of the A component material to the B component material is 1:1.

[0042] Specifically, the anchoring material 2 is divided into A and B components, which are mixed uniformly in a certain proportion through the grouting mixer 11 and then injected through the inner wall of the hollow rod body 3. After the anchoring material 2 overflows from the drill bit 1, high-pressure grouting is carried out in the closed space of the anchoring section and penetrates into the fractures of the hole wall, and solidifies within 30-120 seconds, thereby achieving rapid anchoring of the end of the anchor rod.

[0043] The hollow rod body 3 is made of high-elongation steel material, which can elongate to prevent being pulled off when the surrounding rock of the tunnel deforms greatly. The outer surface of the hollow rod body 3 is provided with left-handed or right-handed standard wave thread, and the inside of the hollow rod body 3 is hollow, serving as a grouting channel.

[0044] The grouting controller 4 comprises a hollow core pipe 41 and an outer shell 42. Both ends of the hollow core pipe 41 are connected with the hollow rod body 3 through standard wave internal threads, and the outer shell 42 is wrapped outside the hollow core pipe 41. The outer shell 42 and the hollow core pipe 41 are sealingly connected through a metal fastening ring 43. The closed space 44 is formed between the outer wall of the hollow core pipe 41 and the inner wall of the outer shell 42, and water-absorbing material is pre-placed in the closed space 44. The middle part of the hollow core pipe 41 is provided with symmetrically distributed one-way valve grout outlets 45. The opening pressure of the one-way valve grout outlets 45 is higher than the air pressure and water pressure during anchor drilling. The grouting controller 4 connects the two hollow rod bodies 3 to form a grouting channel. During grouting, the grout flows from the one-way valve grout outlets 45 on the hollow core pipe 41 into the outer shell 42, and the outer shell 42 expands to completely block the drill hole, forming a closed space in the anchoring section. After the grouting controller expands, the anchor rod is centered in the drill hole.

[0045] According to the different expansion principles of the grouting controller 4, it can be divided into the following three types: ① Grouting (water) expansion type: the outer shell 42 is made of flexible material, and under a certain pressure, the grout (water) can enter the closed space 44 through the grouting hole 45 of the one-way valve. Grout (water) can only be injected and cannot flow out, causing the outer shell 42 to expand outward, thereby playing the role of plugging the borehole. ② Reaction expansion type: the outer shell 42 is made of flexible material, and the closed space 44 is pre-installed with water-absorbing materials such as water-absorbing resin, water-swelling rubber, and foaming polyurethane. Under a certain pressure, water can enter the closed space 44 through the grouting hole 45 of the one-way valve. The above-mentioned water-absorbing materials react rapidly when they come into contact with water, and their volume can expand by more than 600%, causing the flexible outer shell 42 to expand and plug the borehole. ③ Steel expansion shell type: the outer shell 42 is made of folded steel. Under super-high pressure, the grout (water) entering the closed space 44 causes the steel outer shell 42 to irreversibly stretch and expand, thereby plugging the borehole. At this time, even if the grouting (water) pressure is reduced, the steel outer shell 42 will still maintain its expanded shape. ④ When installing the anchor rod at the top of the tunnel, the grouting controller can temporarily fix the anchor rod in the borehole after expansion, preventing the anchor rod from sliding out or falling off, and avoiding the need for additional manual or mechanical temporary support during construction.

[0046] The grouting controller of the present application ensures that the anchoring material is grouted densely and uniformly around the rod body without affecting the drilling, hole cleaning and force bearing of the anchor rod, thereby greatly improving the anchoring force. Specifically: ① The grouting controller can connect two hollow rod bodies 3 together to form a grouting channel, effectively transmitting the anchor rod tension, and not affecting the drilling, hole cleaning and hole cleaning of the anchor rod; ② The grouting controller can expand at the initial stage of grouting to completely plug the borehole and form a closed space in the anchoring section, thereby preventing the anchoring material from flowing, saving materials, and allowing high-pressure grouting of the anchoring section to improve grouting fullness and density. ③ The grouting controller can center the anchor rod in the borehole after expansion, avoiding problems such as insufficient annular thickness of the anchoring material when the rod body contacts the hole wall.

[0047] The outer surface of the hollow rod body 3 on the right side of the grouting controller is wrapped with a corrosion-resistant sleeve 5, which mainly prevents the anchor rod from rusting. Secondly, the surface of the corrosion-resistant sleeve is printed with text or barcode information such as anchor rod model specifications, batch, application project name, etc., thereby enabling the anchor rod to be traced throughout the entire process.

[0048] The high-pressure grouting end anchor type self-drilling prestressed anchor rod also includes a connecting sleeve 6 and a grout stopper 7. The connecting sleeve 6 serves to connect the two rod bodies, acting as an extension. The grout stopper 7 is arranged at the free end of the hollow rod body 3, and the grout stopper 7 is located in front of the limiting pad 8. When the free section of the anchor rod needs to further improve the durability or full-length anchoring force of the anchor rod, the free section can be injected with cement grout, polyurethane and other post-grouting materials, and the grout stopper 7 can prevent the grout from overflowing from the hole.

[0049] The high-pressure grouting end anchor type self-drilling prestressed anchor rod further comprises a limiting pad plate 8, which is a tapered pad plate, and a circle of retreat-preventing teeth 81 is arranged at the central circular hole of the limiting pad plate 8, the retreat-preventing teeth 81 are tightly engaged with the wave-shaped thread on the outer surface of the hollow rod body 3, and the limiting pad plate 8 can only advance on the hollow rod body 3 but cannot retreat. One corner of the limiting pad plate 8 is raised and provided with a through hole 82, and the high-strength steel wire 10 passes through the through holes 82 of the plurality of limiting pad plates 8 in sequence to connect the plurality of anchor rods to form an integral force bearing structure.

[0050] Specifically, the limiting pad plate 8 is a tapered pad plate, a circle of retreat-preventing teeth is arranged at the central circular hole, and the diameter of the circular hole is slightly smaller than the outer diameter of the hollow rod body 3. The retreat-preventing teeth are tightly engaged with the wave-shaped thread on the outer surface of the hollow rod body 3, and under the action of extrusion force and frictional resistance, the limiting pad plate 8 can only advance on the hollow rod body 3 but cannot retreat. Secondly, one corner of the pad plate is raised and provided with a through hole through which the high-strength steel wire 10 can pass. The steel wire 10 can pass through the through holes of the plurality of pad plates in sequence to connect the plurality of anchor rods to form an integral force bearing structure, thereby avoiding the overall failure caused by the failure of individual anchor rods.

[0051] Thanks to the retreat-preventing teeth, the prestress of the rod body can be applied by only pulling the hollow rod body 2 outward with the limiting pad plate 8 abutting against the surrounding rock surface and stopping the pulling when the pulling force reaches the design requirement. This tensioning type prestress application method avoids the problems such as nut tightening failure and the like, and the prestress application value of the rod body can be directly measured during construction without the need of converting the torque into the axial force.

[0052] The nut 9 is arranged behind the limiting pad plate 8 on the hollow rod body 3, and after the prestress of the anchor rod is applied, the nut 9 is tightened to prevent the retreat-preventing teeth of the limiting pad plate 8 from failing.

[0053] The high-pressure grouting end anchor type self-drilling prestressed anchor rod of the application uses A and B two-component anchoring materials, the anchoring materials can be solidified within 30-120 seconds, thereby realizing the rapid anchoring of the end of the anchor rod; the limiting pad plate has retreat-preventing teeth, and the hollow rod body can only advance but cannot retreat. Therefore, during construction, the prestress can be applied by only pulling the hollow rod body 3 outward with the limiting pad plate 8 abutting against the surrounding rock surface, the operation is simple, and the prestress value is clear; the high-strength steel wire connects the plurality of anchor rods to form a cooperative force bearing structure, thereby avoiding the overall group anchor support failure caused by the failure of local anchor rods.

[0054] The grouting controller can ensure that the anchoring material is grouted densely and uniformly wrapped around the rod body without affecting the anchor rod drilling, hole cleaning and stress, thereby greatly improving the anchoring force. Specifically as follows: ① the grouting controller can connect two hollow rod bodies to form a grouting channel, effectively transfer the anchor rod tension, and not affect the anchor rod drilling, hole cleaning and hole cleaning; ② the grouting controller can be inflated at the initial stage of grouting to completely block the drilling hole and form a closed space in the anchoring section, thereby preventing the anchoring material from flowing, saving materials, and enabling high-pressure grouting of the anchoring section to improve grouting fullness and density. ③ the grouting controller can allow the anchor rod to be centered in the drilling hole after inflation, avoiding problems such as insufficient annular thickness of the anchoring material when the rod body contacts the hole wall.

[0055] Based on the above high-pressure grouting end anchor type self-drilling prestressed anchor rod, the present application also relates to a construction method of a high-pressure grouting end anchor type self-drilling prestressed anchor rod, which comprises the following steps:

[0056] Step 1. Preparation for construction. Prepare the anchor rod drilling machine, grouting system, rod body and accessories, anchoring material, high-pressure air (water) and other working conditions required for anchor rod construction.

[0057] Step 2. Drilling and hole cleaning. Connect the assembled anchor rod to the anchor rod drilling machine, start the drilling machine to drive the rod body to rotate, and the drill bit cuts the surrounding rock to drill a hole. When the designed depth is reached, connect the high-pressure air (water) pipe and clean the drilling hole with high-pressure air (water).

[0058] Step 3. First, apply axial force to the anchor rod so that the anchor rod drill bit rests on the surrounding rock at the bottom of the hole. Second, depending on the type of grouting controller, different methods are used to inflate the shell of the grouting controller to block the drilling hole. For the grouting (water) expansion type, increase the air pressure or water pressure to inflate (liquid) expansion. The high-pressure air (water) pipe can also be removed and connected to the grouting pipe, and the high-pressure grouting of the anchoring material slurry allows it to inflate with liquid. For the reaction expansion type, increase the water pressure to make the contents react and expand when water is added. For the steel expansion shell type, high-pressure water or high-pressure grouting can be used to inflate it. Finally, stop the water, air or slurry after stabilizing at a certain pressure for a period of time, and the anchor rod cannot be easily pulled out, which is considered to be the inflation of the grouting controller.

[0059] Step 4. High-pressure grouting of the end anchor. The two feed pipes of the high-pressure grouting pump are placed in the two storage tanks storing the anchoring material A and B components, and the grouting pipe is connected to the hollow rod body for high-pressure grouting. The grouting parameters are determined according to the chemical composition of the surrounding rock, the characteristics of the structural plane, etc., so that the mixed anchoring material fixes the anchoring section of the anchor rod in the surrounding rock. Do not shake the rod body for a short time after grouting is completed.

[0060] Step 5. Pre-stress application. Install the limiting pad plate to the hollow rod body, use the anchor rod installation tool to tension the hollow rod body, and continuously push the limiting pad plate to compress the surrounding rock surface. When the tension reaches the requirement, loosen the hollow rod body, and install the nut behind the limiting pad plate.

[0061] Step six 6. After all the anchor rods are installed, use high-strength steel wire to connect the limiting pad plates of the key parts of the anchor rods into a net.

[0062] Step 7. Anchor rod post-grouting. When further protection of the anchor rod is needed, a small hole reserved on the pad plate and the grouting plug can be used to insert a grouting pipe, and the free end of the hollow rod body can be grouted with cement slurry, so as to enhance the anchoring force and the corrosion resistance of the anchor rod.

[0063] The above describes the present application in an exemplary manner in combination with the drawings, and it is obvious that the present application is specifically implemented. It is not limited by the above-mentioned manner, and as long as various non-essential improvements are made by using the technical solutions of the present application, or the concept and technical solutions of the present application are directly applied to other occasions without improvement, they are all within the protection scope of the present application.

Claims

1. A high-pressure grouting end-anchored self-drilling prestressed anchor rod, characterized in that: The anchor rod comprises a drill bit (1), an anchoring material (2), a hollow rod body (3), a grouting controller (4) and a grouting mixer (11), the drill bit (1) is connected to the end of the anchoring section of the hollow rod body (3), the grouting controller (4) is installed on the hollow rod body (3), the two ends of the grouting controller (4) are connected with the hollow rod body (3) respectively, the grouting mixer (11) is communicated with the end of the free end of the hollow rod body (3), the hollow rod body (3) is internally provided with a grouting channel, the anchoring material (2) is stirred uniformly in the grouting mixer (11), and the anchoring material (2) is injected through the grouting channel of the hollow rod body (3); the hollow rod body (3) is made of high-elongation steel material, the outer surface of the rod body of the hollow rod body (3) is provided with left-handed or right-handed standard wave-shaped threads, the inside of the hollow rod body (3) is a hollow structure and serves as the grouting channel; the grouting controller (4) comprises a hollow core pipe (41) and a shell (42), the two ends of the hollow core pipe (41) are connected with the hollow rod body (3) through standard wave-shaped internal threads respectively, the shell (42) is wrapped outside the hollow core pipe (41), and the two ends of the shell (42) and the hollow core pipe (41) are sealingly connected through a metal fastening ring (43); a closed space (44) is formed between the outer wall of the hollow core pipe (41) and the inner wall of the shell (42), water-absorbing material is prearranged in the closed space (44), and the middle part of the hollow core pipe (41) is provided with symmetrically distributed one-way valve grout holes (45).

2. A high-pressure grouting end-anchored self-drilling prestressed anchor rod according to claim 1, characterized in that: The anchoring material (2) is A and B two-component material mixed at a certain ratio, after the anchoring material (2) overflows from the drill bit (1), high-pressure grouting is carried out in the closed space of the anchoring section and permeated into the hole wall fracture, and the anchoring material (2) can be solidified within 30-120 seconds to quickly anchor the end of the anchor rod.

3. A high-pressure grouting end-anchored self-drilling prestressed anchor rod according to claim 1, characterized in that: The grouting controller (4) connects the two hollow rod bodies (3) to jointly form the grouting channel, when grouting, the slurry flows from the one-way valve grout holes (45) on the hollow core pipe (41) to the shell (42), the shell (42) expands to completely block the drill hole, a closed space is formed in the anchoring section, and the anchor rod is centered in the drill hole after the grouting controller expands.

4. A high-pressure grouting end-anchored self-drilling prestressed anchor rod as claimed in claim 3, characterized in that: The anchor rod further comprises a limiting pad plate (8), the limiting pad plate (8) is a conical pad plate, a circle of retreat-stop teeth (81) is arranged at the central hole of the limiting pad plate (8), the retreat-stop teeth (81) are tightly engaged with the wave-shaped threads on the outer surface of the hollow rod body (3), and the limiting pad plate (8) can only advance on the hollow rod body (3) and cannot retreat.

5. A high-pressure grouting end-anchored self-drilling prestressed anchor rod as claimed in claim 4, characterized in that: One corner of the limiting pad plate (8) is raised and provided with a through hole (82), high-strength steel wires (10) pass through the through holes (82) of the plurality of limiting pad plates (8) in sequence to connect the plurality of anchor rods to form an integrated force-bearing structure.

6. A high-pressure grouting end-anchored self-drilling prestressed anchor rod as claimed in claim 4, characterized in that: The anchor rod further comprises a grout-stopping plug (7), the grout-stopping plug (7) is arranged at the free end of the hollow rod body (3) and located in front of the limiting pad plate (8).

7. A construction method of a high-pressure grouting end-anchored self-drilling prestressed anchor rod, characterized in that: The construction method of the high-pressure grouting end anchor type self-drilling prestressed anchor rod according to any one of claims 1 to 6 comprises the following steps: Step 1. Construction preparation: prepare the anchor rod drill, grouting system, rod body and accessories, anchoring material, high-pressure air / water working conditions required for anchor rod construction; Step 2. Drilling and hole cleaning: connect the assembled anchor rod to the anchor rod drill, start the drill to rotate the rod body, the drill bit cuts the surrounding rock to drill a hole, and when the designed depth is reached, connect the high-pressure air / water pipe to clean the hole with high-pressure air / water; Step 3. First, apply axial force to the anchor rod so that the anchor rod drill bit rests on the hole bottom surrounding rock; second, according to the type of grouting controller, different ways are taken to make the shell of the grouting controller expand to block the hole; Step 4. High-pressure end anchor grouting: the two feed pipes of the high-pressure grouting pump are respectively placed in the two storage tanks storing components A and B of the anchoring material, and the grouting pipe is connected to the hollow rod body for high-pressure grouting; Step 5. Pre-stress application: install the limiting pad plate on the hollow rod body, use the anchor rod installation tool to tension the hollow rod body, and continuously push the limiting pad plate to press the surrounding rock surface, when the tensioning force reaches the required value, loosen the hollow rod body, and install the nut behind the limiting pad plate; Step 6. After all the anchor rods are installed, use high-strength steel wire to connect the limiting pad plates at key positions of the anchor rods to form a net; Step 7. Post-grouting of anchor rod: when further protection of the anchor rod is needed, a small hole reserved on the limiting pad plate and the grouting pipe can be inserted through the hole to grout the free end of the hollow rod body with cement slurry.

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