Mining anchor rod suitable for drilling, blasting and tunneling of jointed hard rock roadway and construction method of mining anchor rod

Abstract

The invention discloses a mining anchor rod suitable for drilling and blasting tunneling of a jointed hard rock roadway and a construction method of the mining anchor rod, and relates to the technical field of hard rock mine roadway construction. Comprising an anchor rod outer pipe, an anchor rod inner rod, a flexible anchor cable, a tray, an anchor rod dynamometer, a gasket and a torque nut, the anchor rod inner rod is movably connected to the interior of the anchor rod outer pipe, the end of the anchor rod inner rod is connected with the flexible anchor cable, and the tray, the anchor rod dynamometer, the gasket and the torque nut are sequentially arranged at the end of the flexible anchor cable. The anchor rod body is designed to be of a two-layer structure of the anchor rod inner rod and the anchor rod outer pipe, the anchor rod outer pipe is anchored through an anchoring agent, the anchor rod inner rod and the anchor rod outer pipe are fastened through threads, after a rock body on the surface layer of a roadway falls off and is cleaned, due to the fact that a screwing stroke with a certain length is reserved in the anchor rod outer pipe, the situation that the exposed length of the anchor rod is unqualified cannot be caused, and the service life of the anchor rod is prolonged. And the flexible anchor cable is arranged at the end part of the anchor rod, so that the continuous drilling of the inner rod of the anchor rod is not influenced.

Description

Technical Field

[0001] The invention relates to the technical field of hard rock mine tunnel construction, and in particular to a mining anchor suitable for drilling and blasting in jointed hard rock tunnels and a construction method thereof. Background Art

[0002] During the excavation of mine tunnels, roof management has always been an extremely important step. Plastic failure of the tunnel roof is an important reason for the overall rupture of the roof, large deformation of the surrounding rock, failure of support, and then roof collapse in the tunnel. The support design is also based on the geometric characteristics of the plastic zone of the surrounding rock for roof collapse control design. For areas with poor surrounding rock stability, the excavation of hard rock tunnels in mines is usually carried out by blasting, and the maintenance of the roof is the support form of anchor nets. In order to ensure the safety of personnel and equipment to the greatest extent, the construction process is carried out in a one-by-one manner, and resin anchors are currently widely used for roof surrounding rock protection. During the tunnel excavation process, due to the secondary stress balance of the surrounding rock and the influence of blasting vibration, the roof anchor failure often occurs. Under the influence of rock gravity, after the floating stone in the anchor net is cleaned, the anchor has been bent. The exposed allowable length of the anchor exceeds the national standard specification and cannot be adjusted again. It usually needs to be reprocessed or re-anchored, which causes material waste and fails to achieve effective control of the surrounding rock. Summary of the invention

[0003] The purpose of the present invention is to provide a mining anchor rod suitable for drilling and blasting in jointed hard rock tunnels and a construction method thereof, so as to solve the problem that the existing anchor rods cannot be readjusted after secondary stress or blasting after anchoring, resulting in failure and inability to adjust.

[0004] In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a mining anchor suitable for drilling and blasting in jointed hard rock tunnels, characterized in that it includes an anchor outer tube, an anchor inner rod, a flexible anchor cable, a tray, an anchor dynamometer, a gasket and a torque nut, the anchor inner rod is movably connected to the inside of the anchor outer tube, the end of the anchor inner rod is connected to the flexible anchor cable, and the end of the flexible anchor cable is sequentially provided with a tray, an anchor dynamometer, a gasket and a torque nut.

[0005] A further technical solution is that a hexagonal nut is provided at the end of the anchor rod inner rod, the anchor rod outer tube is a hollow steel tube with one end open, the anchor rod inner rod is a solid steel tube, and the anchor rod inner rod is threadedly connected to the anchor rod outer tube.

[0006] A further technical solution is that the reserved screw-in length of the inner rod of the anchor rod is 500-600 mm.

[0007] A further technical solution is that protrusions are radially distributed on the outer side of the end of the outer tube of the anchor rod.

[0008] A further technical solution is to use the anchor rod in a construction method as follows:

[0009] Step 1: Drilling of tunnel roof

[0010] The roof anchor drilling rig is used for construction, and vertical holes are drilled into the roof as anchor holes;

[0011] Step 2: Deliver anchoring agent

[0012] Fill the anchor holes with resin anchors one by one, and slowly push the resin anchors to the bottom of the holes with the outer tube of the anchor;

[0013] Step 3: Stir the anchoring agent

[0014] Use a stirring connector to connect the drilling rig to the end of the anchor outer tube. When the anchor reaches the bottom of the hole, start the drilling rig and push it to the bottom of the hole while stirring. Stir quickly for 30 to 50 seconds and then stop.

[0015] Step 4: Install the inner rod of the anchor

[0016] Use an extended connecting sleeve, one end of which is connected to the inner rod of the anchor bolt, and the other end is connected to the anchor drilling rig. Start the drilling rig to screw in at the lowest drilling speed. When the inner rod of the anchor bolt is screwed in to the designed penetration, stop screwing in the inner rod of the anchor bolt.

[0017] Step 5: Tighten the anchor

[0018] Wait for 6 to 7 minutes and then start the drilling rig again, so that the pallet can quickly press the top plate, so that the anchor has a large pre-tension force and the pallet is close to the rock surface; record the initial stress value of the anchor dynamometer.

[0019] A further technical solution is that the deviation between the actual diameter of the anchor hole and the designed diameter is controlled within 1mm; the anchor hole depth error is in the range of 0mm to 30mm; the deviation between the actual drilling angle of the anchor hole and the designed angle is not greater than 5°; the spacing error of the anchor holes does not exceed 100mm.

[0020] A further technical solution is that the resin anchoring agents are loaded in sequence according to the order of the coagulation speed of the anchoring agents, first fast and then slow.

[0021] A further technical solution is that the tightening torque of the torque nut in the fifth step shall not be less than 100 N·m.

[0022] A further technical solution is that the method further includes secondary installation and pre-tightening of the anchor rod when the top rock mass falls and causes the top rock to lose its anchoring force. The specific steps are as follows:

[0023] Step 1: Remove the torque nut, gasket, anchor dynamometer and tray at the end of the flexible anchor cable;

[0024] Step 2: Use the extended connecting sleeve to continue screwing the inner rod of the anchor rod. The screwing stroke is the thickness of the topsoil rock and soil falling off.

[0025] Step 3: Reinstall the tray, anchor dynamometer, gasket, and torque nut, tighten the torque nut through the anchor drilling rig, and the tray quickly presses the top plate to give the anchor a large pre-tension, so that the tray is close to the rock surface.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The flexible anchor cable is designed as a flexible structure, while the rigid structure of the anchor rod outer tube and the anchor rod inner rod fits tightly with the stable rock mass. During the falling of the surface rock mass in the tunnel, the flexible anchor cable at the end of the anchor rod deforms together with the rock mass, which will not cause deformation of the lower anchor rod body.

[0028] The main body of the anchor rod is designed as a two-layer structure of an inner rod and an outer tube. The outer tube is anchored by an anchoring agent, and the inner rod and the outer tube are fastened by threads. When the surface rock of the tunnel falls off and is cleaned, a certain length of rotation stroke is reserved inside the outer tube, which will not cause the exposed length of the anchor rod to be unqualified, and since a flexible anchor cable is set at the end of the anchor rod, it will not affect the continued drilling of the inner rod. The inner rod and the outer tube are designed as relatively independent structures. For temporary support of the tunnel roof, the inner rod can be recycled many times. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram showing the use status of the anchor rod in the present invention.

[0030] Figure 2 It is a schematic diagram of the structure of the anchor rod in the present invention.

[0031] Figure 3 It is a schematic diagram of the secondary installation and pre-tightening of the anchor rod in the present invention.

[0032] In the figure: 1-anchor outer tube, 2-anchor inner rod, 3-flexible anchor cable, 4-tray, 5-anchor dynamometer, 6-washer, 7-torque nut, 8-hexagonal nut, 9-reserved screw-in space, 10-rigid inner rod section, 11-outer rod section, 12-anchoring section, 13-anchor hole, 14-rock mass, 15-reserved section. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] Example 1

[0035] Figure 1 , 2 It shows: a mining anchor suitable for drilling and blasting in jointed hard rock tunnels, characterized in that it includes an anchor outer tube 1, an anchor inner rod 2, a flexible anchor cable 3, a tray 4, an anchor dynamometer 5, a gasket 6 and a torque nut 7. The end of the anchor inner rod 2 is connected to the flexible anchor cable 3, and the end of the flexible anchor cable 3 is sequentially provided with a tray 4, an anchor dynamometer 5, a gasket 6 and a torque nut 7. A hexagonal nut 8 is provided at the end of the anchor inner rod 2. The anchor outer tube 1 is a hollow steel tube with an open end, and the anchor inner rod 2 is a solid steel tube. The anchor inner rod 2 is threadedly connected to the anchor outer tube 1. The reserved screw-in length of the anchor inner rod 2 is 500 to 600 mm. There are protrusions radially distributed on the outer side of the end of the anchor outer tube 1.

[0036] The outer tube 1 of the anchor rod is a hollow steel tube, and the outer and inner sides of the steel tube are designed with corresponding threads. The outer threads are mainly used to fasten with the outer rock wall, and the inner threads are mainly used to fasten with the inner rod 2 of the anchor rod.

[0037] The anchoring agent of the anchor outer tube 1 is resin, and the length of the anchoring section accounts for about one-third of the total length of the anchor. The length of the anchor outer tube 1 is designed to be longer than the length of the anchor inner rod 2. When the surface rock mass fails to support the anchor due to blasting vibration and natural instability, the anchor inner rod 2 can continue to be screwed in to provide prestress. For general support design, the reserved screw-in length is controlled between 500mm and 600mm.

[0038] The end side of the inner rod 2 of the anchor rod is designed as a flexible anchor cable 3. The inner rod 2 of the anchor rod is made of solid steel material, which is a rigid material. The flexible anchor cable 3 at the end is mainly used to resist the displacement deformation of the surface rock mass. It can deform with the deformation of the rock and absorb the strain energy of the rock to the maximum extent. Even if the rock mass breaks and falls, the anchor cable is flexible and will not deform rigidly, which will not affect the secondary pre-tightening construction of the anchor rod.

[0039] A hexagonal nut 8 is provided at the end of the anchor rod inner rod 2. When the anchor rod needs secondary pre-tightening, an extended connecting sleeve matching the hexagonal nut 8 is selected to perform secondary drilling through an anchor drilling rig.

[0040] The end of the anchor rod mainly consists of a torque nut 7, a gasket 6, an anchor rod dynamometer 5, and a tray 4. The application of the anchor rod preload mainly depends on the tightening of the torque nut 7. The anchor rod dynamometer 5 can be installed according to construction needs to measure the stress on the anchor rod. If the anchor rod is used for temporary support in a mine, the inner bar 2 of the anchor rod can be disassembled and reused. The anchor rod cooperates with the anchor net to support the top plate surrounding rock, and the tray 4 of the anchor rod should be close to the protective net. The protective nets are locked at an angle, and steel wire is used for bundling on site. The overlap length between the protective nets is controlled at about 150mm to 200mm.

[0041] The installation process of the above anchor rod is as follows:

[0042] Step 1: Drilling of tunnel roof

[0043] The roof anchor drilling rig is used for construction, and the vertical holes are drilled into the roof as anchor holes. The deviation between the actual diameter of the anchor hole and the designed diameter is controlled within 1mm; the anchor hole depth error is within the range of 0mm to 30mm; the deviation between the actual drilling angle of the anchor hole and the designed angle is not greater than 5°; the spacing error of the anchor holes does not exceed 100mm.

[0044] Step 2: Deliver anchoring agent

[0045] The anchoring agent is sequentially loaded into the anchor hole. The resin anchoring agent is sequentially loaded in the order of the coagulation speed of the anchoring agent being fast first and then slow. The resin anchoring agent is slowly pushed to the bottom of the hole by the anchor outer tube 1.

[0046] Step 3: Stir the anchoring agent

[0047] Use a stirring connector to connect the drilling rig to the end of the anchor outer tube 1. When the anchor reaches the bottom of the hole, start the drilling rig while stirring and push it to the bottom of the hole. Stir quickly for 30 to 50 seconds and then stop.

[0048] Step 4: Install the inner rod of the anchor

[0049] An extended connecting sleeve is used, one end of which is connected to the anchor inner rod 2, and the other end is connected to the anchor drilling rig. The drilling rig is started to screw in at the lowest drilling speed. When the anchor inner rod 2 is screwed in to the designed penetration, the screwing in of the anchor inner rod 2 is stopped.

[0050] Step 5: Tighten the anchor

[0051] Wait for 6 to 7 minutes and then start the drill again to remove the plug, so that the tray 4 can quickly press the top plate, so that the anchor has a large pre-tightening force and the tray 4 is close to the rock surface. After the anchor construction is completed, the angle and exposed length of the anchor must be carefully checked, and the torque and pull-out resistance must be tested. If the inspection fails, it needs to be re-drilled. The tightening torque of the torque nut 7 shall not be less than 100N·m.

[0052] Step 6: For anchor rods that require stress monitoring, record their initial stress values.

[0053] The secondary operation process after the failure of anchor support is as follows: Due to the collapse of the top rock mass, the top rock loses its anchoring force, and secondary installation and pre-tightening of the anchor are required.

[0054] The first step: dismantle the torque nut 7, the gasket 6, the anchor dynamometer 5 and the tray 4 at the end of the flexible anchor cable 3.

[0055] Step 2: Use the extended connecting sleeve to continue screwing the inner rod 2 of the anchor rod, and the screwing stroke is the thickness of the topsoil rock and soil falling.

[0056] Step 3: Reinstall the tray 4, anchor dynamometer 5, gasket 6, and torque nut 7. Tighten the torque nut 7 through the anchor drilling rig. The tray 4 quickly presses the top plate, so that the anchor has a large pre-tension force and the tray 4 is close to the rock surface. After the anchor construction is completed, the angle and exposed length of the anchor must be carefully checked and the torque force tested. The tightening torque of the torque nut 7 shall not be less than 100N·m.

[0057] Example 2

[0058] Take the excavation of the lower ore layer cutting tunnel of Kunyang Phosphate Mine No. 2 as an example. The lithology of the lower ore layer is mainly banded phosphorite, sandy phosphorite and gravel phosphorite. The surface fissures are developed and filled with mud. The rock mass belongs to hard rock, the rock mass integrity is broken to relatively complete, and the rock mass quality grade is IV to II. The factors affecting stability are mainly the degree of fissure development and weathering. In the local area where the surface and shallow weathering are strong, the ore body is weathered into sandy soil, which is prone to collapse. The middle and deep parts are weakly weathered, with high mechanical strength and good stability.

[0059] The support parameters are as follows: the anchor rods are made of 20mm diameter threaded steel bars with a spacing of 1000mm and a length of 2000mm; the steel mesh is made of 6mm diameter round steel bars with a mesh size of 120mm×120mm.

[0060] The maximum empty top distance refers to the maximum distance of the working face without support after the excavation working face is blasted or the comprehensive excavator is cut once, which is generally twice the support row. The minimum empty top distance refers to the minimum unsupported distance of the working face after support, which is generally not more than 1 / 2 of the support row. The empty top distance is designed according to the on-site support parameters, and the reserved empty top distance is between 0.5m and 2m.

[0061] Due to the development of joints and fissures in the ore body of the lower ore layer and the short distance between the void and the surrounding rock being affected by water, the surface rock and soil of the roof fell off under the coupling effect of the self-weight stress of the roof surrounding rock and the blasting vibration during on-site construction, resulting in the failure of the original conventional anchor rods.

[0062] The anchor described in Example 1 is used as a temporary support for the cut tunnel roof. The length of the anchor outer tube 1 is designed to be 2550mm, and the length of the anchor inner rod 2 is designed to be 2000mm. Specifically, it is made of solid steel, and a 550mm screw-in space is reserved at the bottom. The anchor outer tube 1 is anchored to the rock wall by a resin anchoring agent, and the anchoring length is 850mm, accounting for about one-third of the total length of the anchor. The length of the flexible anchor cable 3 is designed to be between 450mm-550mm, and is 500mm in this embodiment.

[0063] The connecting rods at the tray 4 are designed to be made of rigid material. The specifications of the tray 4 are 120mm*120mm. The yield strength of the steel of the tray 4 should be no less than 235MPa, and the thickness should be no less than 6mm.

[0064] Anchor rods cooperate with anchor nets to support the top plate surrounding rock. The tray 4 of the anchor rod should be close to the protective net. The protective nets should be locked at different angles. Steel wires should be used for bundling on site. The overlap length between the protective nets should be controlled at around 150mm-200mm.

[0065] The specific steps for anchor bolt installation are as follows:

[0066] Step 1: Drilling

[0067] a) The top plate anchor holes of the tunnel shall preferably be constructed by the top plate anchor drilling rig. The drilling rig model is MQT-130 / 3.2 starter anchor drilling rig, with a working pressure of 0.4-0.63MPa and a rated torque of 132KN.

[0068] b) The anchor holes in the roof should be constructed row by row from the outside to the excavation working face. Each row of anchor holes should be constructed from the middle to the two sides. The anchors should be perpendicular to the roof surrounding rock and the drilling depth should be 2550mm.

[0069] Other requirements for anchor drilling:

[0070] The deviation between the actual diameter of the anchor hole and the designed diameter should be controlled within 1mm; the depth error of the anchor hole should be within the range of 0mm to 30mm; the deviation between the actual drilling angle of the anchor hole and the designed angle should not be greater than 5°; the spacing error of the anchor holes should not exceed 100mm; the rock debris in the drilled hole should be cleaned up.

[0071] Step 2: Deliver anchoring agent

[0072] Load the resin anchor into the anchor hole in sequence. The anchor should be installed in sequence according to the coagulation speed of the anchor, first fast and then slow. Use the anchor outer tube 1 to slowly push the medicine roll to the bottom of the hole. The end of the anchor outer tube 1 on the tray side is designed and processed into an external hexagonal shape.

[0073] Step 3: Stir the anchoring agent

[0074] Use a stirring connector to connect the drilling rig to the end of the anchor outer tube 1, then raise the drilling rig to advance the anchor, slowly raise the air leg to prevent the anchor from being bent at a fast speed. At the same time, it is strictly forbidden to hold the anchor and its accessories by hand. When the anchor reaches the bottom of the hole, start the drilling rig and push it to the bottom of the hole while stirring. Stop after rapid stirring for 30-40S.

[0075] Step 4: Install the inner rod of the anchor

[0076] An extended connecting sleeve is used, and the interior of the sleeve is a hollow structure. The length of the extended connecting sleeve is between 480mm and 560mm, and it is mainly used to place the flexible anchor cable 3. One end is connected to the hexagonal nut 8 of the anchor rod inner rod 2, and the other end is connected to the anchor drilling rig. The torque required for screwing in the anchor rod inner rod 2 is small. The drilling rig is started to screw in the inner rod at the lowest drilling speed. When the anchor rod inner rod 2 is screwed in to the designed penetration, the screwing in of the anchor rod inner rod 2 is stopped.

[0077] Step 5: Tighten the anchor

[0078] After the anchoring agent mixing is stopped and the anchor inner rod 2 is installed, the tray 4, gasket 6, anchor dynamometer 5, and torque nut 7 are installed. The anchor drilling rig is connected to the torque nut 7 through a connector, and the drilling rig is started to quickly press the tray 4 against the top plate, so that the anchor has a large pre-tension force and the tray is close to the rock surface. After the anchor construction is completed, the angle and exposed length of the anchor must be carefully checked, and the torque force and pull-out resistance must be tested. If the inspection fails, it needs to be re-drilled. During the installation of the anchor, the tightening torque of the torque nut 7 must not be less than 100N·m, and the length of the anchor rod exposed by the nut ranges from 10-50mm.

[0079] Step 6: For anchor rods that require stress monitoring, record their initial stress values.

[0080] The secondary operation process after the failure of anchor support is as follows:

[0081] Due to the collapse of the top rock mass, the top rock loses its anchoring force, and secondary installation and pre-tightening of the anchor rod is required.

[0082] The first step: dismantle the torque nut 7, the gasket 6, the anchor dynamometer 5 and the tray 4 at the end of the flexible anchor cable 3.

[0083] Step 2: Use the extended connecting sleeve to continue screwing the inner rod 2 of the anchor rod, and the screwing stroke is the thickness of the topsoil rock and soil falling.

[0084] Step 3: Reinstall the tray 4, anchor dynamometer 5, gasket 6, and torque nut 7. Tighten the torque nut 7 through the anchor drilling rig. The tray 4 quickly presses the top plate, so that the anchor has a large pre-tension force and the tray 4 is close to the rock surface. After the anchor construction is completed, the angle and exposed length of the anchor must be carefully checked and the torque force tested. The tightening torque of the torque nut 7 shall not be less than 100N·m.

[0085] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise numerous other modifications and implementations that fall within the scope of the present disclosure. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and modifications may be made to the components or layout. In addition to variations and modifications to the components or layout, other uses will be apparent to those skilled in the art.

Claims

1. A mining anchor suitable for drilling and blasting in jointed hard rock tunnels, characterized by: The invention comprises an anchor rod outer tube (1), an anchor rod inner rod (2), a flexible anchor cable (3), a tray (4), an anchor rod dynamometer (5), a gasket (6) and a torque nut (7); the anchor rod inner rod (2) is movably connected to the inside of the anchor rod outer tube (1); the end of the anchor rod inner rod (2) is connected to the flexible anchor cable (3); and the end of the flexible anchor cable (3) is provided with a tray (4), an anchor rod dynamometer (5), a gasket (6) and a torque nut (7) in sequence.

2. A mining anchor suitable for drilling and blasting in jointed hard rock tunnels according to claim 1, characterized in that: The end of the anchor rod inner rod (2) is provided with a hexagonal nut (8); the anchor rod outer tube (1) is a hollow steel tube with one end open; the anchor rod inner rod (2) is a solid steel tube; the anchor rod inner rod (2) is threadedly connected to the anchor rod outer tube (1).

3. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 2, characterized in that: The reserved screw-in length of the anchor rod inner rod (2) is 500-600 mm.

4. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 2, characterized in that: The outer side of the end of the anchor rod outer tube (1) is radially provided with protrusions.

5. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 1, characterized in that: The construction method using the anchor rod is as follows: Step 1: Drilling of tunnel roof The top plate anchor drilling rig is used for construction, and vertical holes are drilled into the top plate as anchor holes; Step 2: Deliver anchoring agent The resin anchoring agent is sequentially loaded into the anchor hole, and the resin anchoring agent is slowly pushed to the bottom of the hole using the anchor outer tube (1); Step 3: Stir the anchoring agent Connect the drilling machine to the end of the anchor rod outer tube (1) with a stirring connector, start the drilling machine when the anchoring agent reaches the bottom of the hole, stir and push it to the bottom of the hole, stir quickly for 30 to 50 seconds and then stop; Step 4: Install the anchor rod An extended connecting sleeve is used, one end of which is connected to the anchor rod inner rod (2), and the other end is connected to the anchor drilling machine, the drilling machine is started to screw in at the lowest drilling speed, and when the anchor rod inner rod (2) is screwed in to the designed penetration, the screwing in of the anchor rod inner rod (2) is stopped; Step 5: Tighten the anchor After waiting for 6 to 7 minutes, the drilling machine is started again, so that the tray (4) quickly presses the top plate, so that the anchor rod has a large pre-tension force, and the tray is close to the rock surface; the initial stress value of the anchor rod dynamometer (5) is recorded.

6. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 5, characterized in that: The deviation between the actual diameter of the anchor hole and the designed diameter is controlled within 1mm; the depth error of the anchor hole is within the range of 0mm to 30mm; the deviation between the actual drilling angle of the anchor hole and the designed angle is not greater than 5°; the spacing error of the anchor holes does not exceed 100mm.

7. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 5, characterized in that: The resin anchoring agents are loaded in sequence according to the coagulation speed of the anchoring agents, first fast and then slow.

8. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 5, characterized in that: The tightening torque of the torque nut (7) in the fifth step shall not be less than 100 N·m.

9. The mining anchor bolt suitable for drilling and blasting in jointed hard rock tunnels according to claim 5, characterized in that: The method also includes secondary installation and pre-tightening of the anchor rod when the top rock loses its anchoring force due to the collapse of the top rock mass, and the specific steps are as follows: Step 1: dismantle the torque nut (7), the gasket (6), the anchor dynamometer (5) and the tray (4) at the end of the flexible anchor cable (3); Step 2: Use the extended connecting sleeve to continue screwing the anchor rod inner rod (2), and the screwing stroke is the thickness of the topsoil rock mass falling off; Step 3: Reinstall the tray (4), the anchor dynamometer (5), the gasket (6), and the torque nut (7). Tighten the torque nut (7) by the anchor drilling rig. The tray (4) quickly presses the top plate, so that the anchor has a large pre-tension force, and the tray (4) is close to the rock surface.

Images