A prestressed, visualized, large deformation relief anchor bolt and its application method

Abstract

This invention discloses a prestressed, visualized, large deformation yielding anchor bolt and its application method, belonging to the field of underground engineering support technology. It includes an anchor bolt with a serrated anchoring end, miniature hydraulic jacks at intervals in the middle section to enhance anchoring force, and a hydraulic piston-type yielding piston structure and pressure detection device at the tail end of the anchor bolt. The pressure detection device includes a pressure-measuring nut, which is installed close to the piston-type tray on the exposed section of the anchor bolt tail. A prestress monitoring device is connected to the pressure-measuring nut. When the surrounding rock deforms, the surrounding rock squeezes the metal sleeve outwards, and the piston-type tray can move inside it. The honeycomb-shaped elasto-plastic material absorbs the energy released by the deformation of the surrounding rock, thus yielding pressure and controlling the operation of the miniature hydraulic jacks to strengthen the anchoring effect. It achieves both prestress visualization and large deformation yielding functions, while also improving support resistance, and has advantages such as quantifiable and controllable prestress, stable yielding, and safe use.

Description

Technical Field

[0001] This invention relates to a prestressed, visualized, large deformation relief anchor bolt and its application method, which is applicable to areas with large deformation in weak and fractured surrounding rock and belongs to the field of underground engineering support. Background Technology

[0002] Prestressed anchoring technology achieves rock mass stability by applying prestress to anchor bolts, fully utilizing the rock mass's stability. It is a reliable, economical, and minimally disturbing reinforcement technology. Traditional prestressed anchor bolts consist of an anchor head, a bolt body, and a bearing plate. The anchor head uses the anchoring force generated by the anchoring agent to fix the anchor bolt to the surrounding rock, and applies a certain amount of prestress (pre-tightening force) to the anchor bolt to provide active support for the surrounding rock. Generally, applying prestress (pre-tightening force) to the anchor bolt is the main means of active anchor support, and the prestress (pre-tightening force) must be within a suitable range to maximize the active support effect of the anchor bolt. However, due to factors such as surrounding rock deformation and construction installation, the prestress of the anchor bolt can suffer uncontrollable losses after installation. Therefore, obtaining the actual prestress of anchor bolts in underground engineering such as roadways, tunnels, and caverns in real time is crucial to ensuring the full effectiveness of anchor bolt support. At the same time, in underground engineering projects such as roadways and tunnels, the weak and fractured surrounding rock in some high-stress areas is prone to large deformation and damage, making support difficult and causing huge loss of life and property to construction workers and production equipment, and creating technical difficulties for the safe and efficient development of mineral resources in my country.

[0003] Currently, extensive research has been conducted both domestically and internationally on the technical theory of prestressed anchor bolts, primarily focusing on the anchoring system and rock mass reinforcement. Systematic studies have been conducted on the transmission mechanism, action mechanism, and anchoring effect of anchor prestress. However, research on the relationship between anchor prestress and surrounding rock control is relatively limited. From a construction perspective, even simply assessing the prestress of anchor bolts presents numerous unresolved issues. Currently, applying prestress to anchor bolts mainly utilizes torque wrenches, torque amplifiers, and anchor bolt locators. However, these methods suffer from limitations such as the inability to dynamically monitor the magnitude of anchor prestress in real time, low measurement accuracy, and poor reliability, thus offering limited guidance for subsequent anchor bolt support. In conclusion, considering the characteristics of soft, fractured rock tunnels and other underground engineering projects prone to large deformations, there is an urgent need to develop an anchor bolt with prestress visualization and large deformation relief capabilities to meet the stability control requirements of underground engineering projects. Summary of the Invention

[0004] Technical Problem: The purpose of this invention is to overcome the shortcomings of existing technologies and provide a prestressed visualized large deformation yielding anchor rod and its usage method, which is structurally stable, safe and reliable, easy to operate, has visualized prestressing, and allows for large deformation yielding.

[0005] Technical solution: To achieve the above objectives, the present invention provides a prestressed, visualized, large deformation relief anchor bolt, which uses a stepped drilling structure, with the front end being the anchor bolt anchoring drilling section and the rear end being a larger diameter drilling expansion section;

[0006] It includes an anchor bolt, with a serrated anchoring end for stirring the anchoring agent at the end of the anchor bolt. Miniature hydraulic jacks are spaced along the middle section of the anchor bolt to increase the anchoring force according to the deformation of the surrounding rock. A hydraulic piston-type pressure-relief piston structure and a pressure detection device are located at the tail end of the anchor bolt. The pressure-relief piston structure is located in the borehole reaming section and includes a piston-type tray and a metal sleeve. The piston-type tray has a flange for mounting bolts to the surrounding rock, which is fixed to the surrounding rock by tray bolts and tray nuts. A piston head is located at the front end of the piston-type tray within a pre-drilled hole. The piston head matches the metal sleeve to form a piston structure, and the metal sleeve rests against the borehole reaming section. The end of the anchor bolt; the pressure detection device includes a pressure testing nut, which is installed on the exposed section of the anchor bolt tail tightly against the piston tray. A prestress monitoring device is connected to the pressure testing nut, and a pressure sensor is installed inside the prestress monitoring device to monitor the gas pressure inside the prestress monitoring device in real time. All micro hydraulic jacks are connected to the metal sleeve through high elongation hoses. When the surrounding rock deforms, the surrounding rock squeezes the metal sleeve outward. The piston head of the piston tray moves relative to the metal sleeve. When the pressure reaches a preset threshold, the micro hydraulic jack is extended through the high elongation hose to increase the force between it and the borehole wall, thereby completing the pressure relief.

[0007] Furthermore, a pressure valve is provided at the connection between the high elongation hose and the metal sleeve, which can be opened after the pressure reaches a specified value. The miniature hydraulic jack includes a hydraulic cylinder vertically mounted on the anchor rod. The hydraulic cylinder is equipped with a force transmission rod as a hydraulic rod. The end of the force transmission rod is equipped with a 1 / 4 annular force transmission plate that matches the borehole wall structure. The outer surface of the 1 / 4 annular force transmission plate is equipped with multiple protruding spikes.

[0008] Furthermore, a honeycomb-shaped elastomeric material is placed inside a metal sleeve. The metal sleeve matches the end of the piston-type tray to form a piston and piston cylinder structure. Hydraulic medium is filled in the gaps of the honeycomb-shaped elastomeric material inside the metal sleeve. An annular sealing rubber gasket b is provided between the end of the piston-type tray and the metal sleeve for sealing. When the surrounding rock deforms, the surrounding rock squeezes the metal sleeve to move towards the piston-type tray, thereby causing the piston-type tray to squeeze the honeycomb-shaped elastomeric material through the annular sealing rubber gasket b to deform and relieve pressure. At the same time, due to the reduction of space inside the metal sleeve, the volume of the hydraulic medium is compressed, and the hydraulic pressure begins to increase. When the pressure reaches the set value, the pressure valve opens, allowing the hydraulic medium to flow through the high-elongation hose to each miniature hydraulic jack, thereby enabling the miniature hydraulic jack to work.

[0009] Furthermore, the pressure testing nut includes a rotating module connected to a piston-type propulsion module, which in turn is connected to a pressure transmission module. The pressure transmission module is equipped with a rotary valve, which controls the connection between the pressure transmission module and the pressure sensor via a high-elongation hose. The pressure transmission module is positioned between the piston-type propulsion module and the piston-type tray, with a piston connection between them. A ring-shaped sealing rubber gasket a is provided between them to maintain a tight seal. The piston-type propulsion module can move in the pressure transmission module, compressing the gas volume within it. Multiple rotating steel balls are positioned between the piston-type propulsion module and the rotating module to allow free rotation between them. The rotating module, via a thread, can rotate and advance on the anchor rod, pushing the piston-type propulsion module to move in the pressure transmission module. When the piston-type propulsion module compresses gas within the pressure transmission module, the gas volume is compressed. During installation, the piston-type propulsion module needs to be stretched.

[0010] Furthermore, the prestress monitoring device is connected to a rotary valve on the pressure transmission module via a high-elongation hose. The prestress monitoring device is also connected to a miniature air compressor via the high-elongation hose. Compressed air is supplied to the prestress monitoring device and the pressure transmission module via the miniature air compressor. The connection between the miniature air compressor and the prestress monitoring device is controlled by an intake valve located on the pressure sensor.

[0011] Furthermore, the miniature hydraulic jacks are set perpendicular to the anchor bolts, and the number of miniature hydraulic jacks is arranged according to the size of the anchor bolts. Before construction, all miniature hydraulic jacks and pressure valves on the metal sleeves only need to be connected through high-elongation hoses. The metal sleeves and piston trays are assembled during production, and hydraulic medium has been injected into the honeycomb elasto-plastic material during production.

[0012] Furthermore, the diameter of the borehole reaming section is the same as that of the metal sleeve, and the length of the borehole reaming section is the sum of the radial lengths of the metal sleeve and the piston-type tray. This allows the end of the piston-type tray to contact the honeycomb-shaped elasto-plastic material inside the opening of the metal sleeve when the flange part of the piston-type tray is fixed to the surrounding rock wall by the tray bolts and tray nuts, and the end of the metal sleeve abuts against the end face of the borehole reaming section.

[0013] A method for using prestressed, visualized, large deformation anchor bolts, the steps of which are as follows:

[0014] First, anchoring holes are drilled in the surrounding rock. The holes are stepped. After the anchor holes are drilled, the hole enlargement section is constructed. The size of the hole enlargement section matches the metal sleeve. A gap is left between the outer edge of the piston-type tray and the matching part of the metal sleeve and the borehole wall.

[0015] After cleaning the hole, the assembled metal sleeve and piston tray are installed on the anchor rod. The pressure valve and multiple miniature hydraulic jacks are connected through a high elongation hose. Anchoring agent is injected into the bottom of the borehole. The anchor rod is placed in the borehole and rotated. The anchoring agent is stirred evenly through the serrated anchoring end set at the end of the anchor rod. The piston tray is fixed to the surrounding rock through the tray bolts and tray nuts.

[0016] After the anchor bolt is installed in place, the pressure testing nut is initially installed on the exposed section of the anchor bolt behind the piston tray. The rotary valve is opened, and the piston propulsion module and pressure transmission module are squeezed until the air in the pressure transmission module is completely expelled. The micro air compressor, prestress monitoring device and pressure transmission module are connected using a high elongation hose. The rotary valve is closed and the air inlet valve is open.

[0017] Start the miniature air compressor to input compressed air into the prestress monitoring device. When the reading of the prestress monitoring device reaches about 60 to 80% of its range, turn off the miniature air compressor to ensure that the maximum atmospheric pressure in the prestress monitoring device is within its effective range.

[0018] With the inlet valve closed and the rotary valve open, compressed air from the prestress monitoring device enters the pressure transmission module through a high-elongation hose. Once the gas volume stabilizes, rotate the rotary module until the entire pressure testing nut is precisely against the piston-type tray, zeroing the reading of the prestress monitoring device. Then, rotate the rotary module to apply prestress to the anchor bolt. Because one side of the pressure transmission module is already firmly against the piston-type tray, the piston-type propulsion module is pushed along the anchor bolt axis into the pressure transmission module by the rotary module. The air volume inside the pressure transmission module decreases, and the air pressure increases. During this process, the prestress monitoring device remains connected to the pressure transmission module through the high-elongation hose. The gas pressure is obtained through the pressure sensor installed in the prestress monitoring device, which can then be converted into the real-time anchor bolt prestress. The reading of the prestress monitoring device is the converted anchor bolt prestress, which can be read directly, thus achieving visualization of the anchor bolt prestress during application. After the anchor bolt prestress is applied to the design value, close the rotary valve, and then remove the miniature air compressor, prestress monitoring device, and multiple high-elongation hoses.

[0019] Furthermore, when the surrounding rock deforms, the borehole expansion section of the surrounding rock squeezes the metal sleeve, causing it to move relative to the piston tray. In turn, the piston tray pushes the annular sealing rubber pad b to squeeze the honeycomb elasto-plastic material to deform and release pressure. The internal space of the metal sleeve becomes smaller, the hydraulic medium is compressed, and the pressure increases.

[0020] As the surrounding rock deformation continues to increase, when the pressure of the hydraulic medium inside the honeycomb elasto-plastic material exceeds the set value, the pressure forces the pressure valve to open. The hydraulic medium supplies pressure to the miniature hydraulic jack through the high-elongation hose. The force transmission rod pushes the 1 / 4 annular force transmission plate to squeeze the inner wall of the borehole. The protruding spikes designed on the 1 / 4 annular force transmission plate can penetrate into the inner wall of the borehole, increasing the frictional resistance between the anchor bolt and the borehole, thereby improving the safety and stability of the support structure.

[0021] Beneficial Effects: This device utilizes a pressure-measuring nut composed of a rotating module, a piston-type propulsion module, and a pressure transmission module. Combined with a prestress monitoring device and a miniature air compressor, it enables visualization of prestress during anchor bolt prestress application. Before applying prestress to the anchor bolt, the pressure-measuring nut, prestress monitoring device, and miniature air compressor are connected via a high-elongation hose. The miniature air compressor fills the pressure transmission module in the prestress monitoring device and pressure-measuring nut with compressed air. After zeroing, the rotating module in the pressure-measuring nut is rotated to apply prestress. The entire prestress application process can be visualized using the prestress detection equipment. During anchor bolt use, the combination of a metal sleeve, a piston-type tray, and a honeycomb elasto-plastic material enables large deformation pressure relief. Simultaneously, the hydraulic medium within the honeycomb elasto-plastic material's voids and the miniature hydraulic jack increase the frictional resistance between the anchor bolt and the borehole, thus strengthening the support. The entire device not only has the dual functions of prestress visualization and large deformation pressure relief, but also strengthens the support by increasing the frictional resistance between the anchor rod and the borehole. It features simple construction, stable pressure relief, low cost, strong applicability, and easy promotion. It can be applied to the support engineering of underground projects such as soft rock slopes, deep foundation pits, mine roadways, traffic tunnels, and water conservancy and hydropower tunnels. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the drilling structure according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the hole-expanding structure according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the installation of the prestressed visualization large deformation relief anchor bolt of the present invention;

[0025] Figure 4 This is a schematic diagram illustrating the application of prestress to the anchor bolt during large deformation visualization in this invention.

[0026] Figure 5 This is a schematic diagram illustrating the service life of the prestressed large deformation relief anchor bolt of the present invention.

[0027] Figure 6 This is a schematic diagram of the prestress monitoring device in this invention;

[0028] Figure 7 This is a schematic diagram of the structure of the miniature hydraulic jack in this invention.

[0029] In the diagram: 1-surrounding rock, 2-drill hole, 3-anchor bolt, 4-anchoring agent, 5-piston tray, 6-tray bolt, 7-tray nut, 8-pressure testing nut, 9-rotating module, 10-rotating steel ball, 11-annular sealing rubber gasket a, 12-compressed air, 13-prestress monitoring device, 14-rotary valve, 15-annular sealing rubber gasket b, 16-metal sleeve, 17-honeycomb elasto-plastic material, 18-high elongation hose, 19-miniature hydraulic jack, 20-pressure valve, 21-force transmission rod, 22-1 / 4 annular force transmission plate, 23-piston propulsion module, 24-pressure transmission module, 25-serrated anchoring end, 26-pressure sensor, 27-hydraulic medium, 28-miniature air compressor, 29-drilling and reaming section, 30-intake valve, 31-hydraulic cylinder, 32-protruding spike. Detailed Implementation

[0030] The following description, in conjunction with the accompanying drawings, provides a further illustration of one embodiment of the invention:

[0031] like Figure 4 As shown, the present invention provides a prestressed visual large deformation relief anchor bolt, wherein the installed borehole 2 is a variable diameter borehole, and the tail end of the borehole 2 is provided with a borehole enlargement section 29 with a larger diameter.

[0032] It includes an anchor rod 3, with a serrated anchoring end 25 at the end of the anchor rod 3 for stirring the anchoring agent 4. Miniature hydraulic jacks 19 are spaced along the middle section of the anchor rod 3 to increase the anchoring force according to the deformation of the surrounding rock. A hydraulic piston-type pressure-relief piston structure and a pressure detection device are located at the tail end of the anchor rod 3. The pressure-relief piston structure is located in the borehole reaming section 29 and includes a piston-type tray 5 and a metal sleeve 16. The piston-type tray 5 has a flange for mounting bolts to the surrounding rock 1, and the flange is fixed to the surrounding rock 1 by tray bolts 6 and tray nuts 7. A piston head is located at the front end of the piston-type tray 5 within a pre-drilled hole. The piston head matches the metal sleeve 16 to form a piston structure, and the metal sleeve 16 abuts against the end of the borehole reaming section 29. The pressure detection device includes a pressure testing nut 8, which is installed on the exposed section of the tail of the anchor rod 3, closely attached to the piston tray 5. A prestress monitoring device 13 is connected to the pressure testing nut 8, and a pressure sensor 26 is installed inside the prestress monitoring device 13 to monitor the gas pressure inside the prestress monitoring device 13 in real time. All miniature hydraulic jacks 19 are connected to the metal sleeve 16 through a high elongation hose 18. When the borehole 2 deforms, the piston head of the piston tray 5 moves relative to the metal sleeve 16. When the pressure generated by the piston head in the metal sleeve 16 reaches a preset threshold, the miniature hydraulic jacks 19 are extended through the high elongation hose 18 to increase the force between them and the borehole wall of the borehole 2, thereby completing the pressure relief. The high elongation hose 18 is connected to the metal sleeve 16 with a pressure valve 20 that can be opened after the pressure reaches a specified value. The miniature hydraulic jack 19 includes a hydraulic cylinder 31 that is vertically mounted on the anchor rod 3. The hydraulic cylinder 31 is provided with a force transmission rod 21 that serves as a hydraulic rod. The end of the force transmission rod 21 is provided with a 1 / 4 annular force transmission plate 22 that matches the borehole wall structure. The outer surface of the 1 / 4 annular force transmission plate 22 is provided with multiple protruding spikes 32.

[0033] A honeycomb-shaped elastomeric material 17 is disposed inside a metal sleeve 16. The metal sleeve 16 and the end of the piston-type tray 5 are matched to form a piston and piston cylinder structure. Hydraulic medium 27 is disposed in the gaps within the honeycomb-shaped elastomeric material 17 in the metal sleeve 16. An annular sealing rubber gasket b15 is disposed between the end of the piston-type tray 5 and the metal sleeve 16 for sealing. When the surrounding rock 1 deforms, the surrounding rock 1 squeezes the metal sleeve 16 to move towards the piston-type tray 5, thereby causing the piston-type tray 5 to deform the honeycomb-shaped elastomeric material 17 through the annular sealing rubber gasket b15 to relieve pressure. At the same time, due to the reduction of the space inside the metal sleeve 16, the volume of the hydraulic medium 27 is compressed, and the hydraulic pressure begins to increase. When the pressure reaches the set value, the pressure valve 20 opens, allowing the hydraulic medium 27 to flow through the high elongation hose 18 to each miniature hydraulic jack 19, thereby enabling the miniature hydraulic jack 19 to work.

[0034] The pressure testing nut 8 includes a rotating module 9, which is connected to a piston-type propulsion module 23. The piston-type propulsion module 23 is connected to a pressure transmission module 24. The pressure transmission module 24 is equipped with a rotary valve 14, which controls the rotation of the valve. The pressure transmission module 24 is connected to the pressure sensor 26 via a high-elongation hose 18. The pressure transmission module 24 is positioned between the piston-type propulsion module 23 and the piston-type tray 5. A piston connection exists between the piston-type propulsion module 23 and the pressure transmission module 24, and an annular sealing rubber gasket a11 is provided between them to maintain a tight seal. The piston-type propulsion module 23 can perform piston movement in the pressure transmission module 24 and compress the gas volume in the pressure transmission module. Multiple rotating steel balls 10 are provided between the piston-type propulsion module 23 and the rotating module 9 to keep the rotating module 9 and the piston-type propulsion module 23 rotating freely. The rotating module 9 can rotate forward on the anchor rod 3 through the thread and push the piston-type propulsion module 23 to perform piston movement in the pressure transmission module 24. When the piston-type propulsion module 23 compresses in the pressure transmission module 24, it compresses the gas volume; when installing, the piston-type propulsion module 23 needs to be stretched.

[0035] The prestress monitoring device 13 is connected to the rotary valve 14 on the pressure transmission module 24 via a high elongation hose 18. The prestress monitoring device 13 is also connected to a miniature compressed air compressor 28 via the high elongation hose 18. Compressed air 12 is supplied to the prestress monitoring device 13 and the pressure transmission module 24 via the miniature air compressor 28. The connection between the miniature air compressor 28 and the prestress monitoring device 13 is controlled by the air intake valve 30 on the pressure sensor 26.

[0036] Miniature hydraulic jacks 19 are set perpendicular to the anchor bolts 3. The number of miniature hydraulic jacks 19 is arranged according to the size of the anchor bolts 3. Before construction, all miniature hydraulic jacks 19 and pressure valves 20 on the metal sleeves 16 only need to be connected through high-elongation hoses 18. The metal sleeves 16 and piston trays 5 are assembled during production, and hydraulic medium 27 has been injected into the honeycomb elasto-plastic material 17 during production.

[0037] The installation of prestressed visualization large deformation allows the borehole 2 of the anchor rod to be a stepped borehole structure, with the front end being the anchor rod 3 anchoring borehole section and the rear end being the borehole enlargement section 29. The diameter of the borehole enlargement section 29 is the same as that of the metal sleeve 16, and the length of the borehole enlargement section 29 is the sum of the radial lengths of the metal sleeve 16 and the piston-type tray 5. This allows the flange part of the piston-type tray 5 to be fixed to the surrounding rock wall by the tray bolt 6 and the tray nut 7. When the flange part of the piston-type tray 5 is fixed to the surrounding rock wall, the end of the piston-type tray 5 contacts the honeycomb elasto-plastic material 17 inside the opening end of the metal sleeve 16, and the end of the metal sleeve 16 abuts against the end face of the borehole enlargement section 29.

[0038] The method of using the prestressed visualization large deformation relief anchor bolt of the present invention:

[0039] As attached Figure 1 As shown, borehole 2 is constructed in the surrounding rock 1 with a diameter that matches the combined diameter of anchor bolt 3, micro jack 19 and 1 / 4 annular force transmission plate 22.

[0040] As attached Figure 2 As shown, a borehole enlargement section 29 with a borehole diameter matching the size of the piston tray 5 is constructed in the surrounding rock 1.

[0041] As attached Figure 3 As shown, the assembled metal sleeve 16 and piston tray 5 are first installed on the anchor rod 3. The pressure valve 20 and multiple miniature hydraulic jacks 19 are connected through the high elongation hose 18. Anchoring agent 4 is injected into the bottom of the borehole 2. The anchor rod 3 is placed into the borehole 2. The anchor rod 3 is rotated. The anchoring agent 4 is stirred evenly through the serrated anchoring end 25 set at the end of the anchor rod. The piston tray 5 is fixed to the surrounding rock 1 through the tray bolt 6 and tray nut 7.

[0042] After the anchor bolt 3 is installed in place, the pressure testing nut 8 is initially installed on the exposed section of the anchor bolt 3. The rotary valve 14 is opened to squeeze the piston-type propulsion module 23 and the pressure transmission module 24 until the air in the pressure transmission module 24 is completely expelled. The micro air compressor 28, the prestress monitoring device 13, and the pressure transmission module 24 are connected using the high-elongation hose 18. The rotary valve 14 is closed, and the air inlet valve 30 is open. The micro air compressor 28 is started to input compressed air 12 into the prestress monitoring device 13. When the reading of the prestress monitoring device 13 reaches approximately 60-80% of its range, the micro air compressor 28 is turned off, the air inlet valve 30 is closed, and the rotary valve 14 is open. The compressed air 12 in the prestress monitoring device 13 enters the pressure transmission module 24 through the high-elongation hose 18. In step 4, after the gas volume stabilizes, rotate the rotating module 9 so that the entire pressure measuring nut 8 is exactly attached to the piston tray 5, and reset the reading of the prestress monitoring device 13 to zero. Then, rotate the rotating module 9 to apply prestress to the anchor rod. The piston propulsion module 23 moves inside the pressure transmission module 24 under the push of the rotating module 9. The air volume inside the pressure transmission module 24 decreases and the air pressure increases. The gas pressure can be obtained through the pressure sensor 26 installed in the prestress monitoring device 13, and then the real-time anchor rod prestress can be calculated. The reading of the prestress monitoring device 13 is the calculated anchor rod prestress, which can be read directly. This achieves the purpose of visualizing the anchor rod prestress during the application process. After the anchor rod prestress is applied to the design value, close the rotary valve 14, and then remove the miniature air compressor 28, the prestress monitoring device 13, and the multi-section high elongation hose 18.

[0043] As attached Figure 5 As shown, when the surrounding rock 1 deforms, it compresses the metal sleeve 16, causing it to move relative to the piston-type tray 5. The piston-type tray 5 then pushes the annular sealing rubber gasket b15 to compress the honeycomb-shaped elasto-plastic material 17, causing it to release pressure. The internal space of the metal sleeve 16 decreases, the hydraulic medium 27 is compressed, and the pressure increases. As the deformation of the surrounding rock 1 continues to increase, when the pressure of the hydraulic medium 27 exceeds the set value, the pressure valve 20 opens. The hydraulic medium 27 supplies pressure to the miniature hydraulic jack 19 through the high-elongation hose 18. The force transmission rod 21 pushes the 1 / 4 annular force transmission plate 22 to compress the inner wall of the borehole 2. Simultaneously, the protruding spikes 32 on the 1 / 4 annular force transmission plate 22 pierce the inner wall of the borehole 2 to increase the frictional resistance between the anchor rod 3 and the borehole 2, thereby improving the safety and stability of the support structure.

[0044] In summary, the invention achieves visualized monitoring of anchor bolt prestress by using a pressure-measuring nut, a prestress monitoring device, and a miniature air compressor; it achieves large deformation pressure relief by using a combination of metal sleeves, honeycomb elasto-plastic materials, and piston-type trays; and it has good adaptability to drilling at any depth by using segmented anchor bolts.

[0045] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art and those skilled in construction can make various improvements or substitutions without departing from the technical principles of the present invention, and these improvements or substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A prestressed, visualized, large deformation relief anchor bolt, characterized in that: The drill hole (2) used is a stepped drill hole structure, with the front end being the anchor rod (3) anchoring the drill hole section and the rear end being the larger diameter drill hole expansion section (29). It includes an anchor rod (3), the end of the anchor rod (3) is provided with a serrated anchoring end (25) for stirring the anchoring agent (4), the middle section of the anchor rod (3) is provided with micro hydraulic jacks (19) for increasing the anchoring force according to the degree of deformation of the surrounding rock, and the tail end of the anchor rod (3) is provided with a hydraulic piston type pressure relief piston structure and a pressure detection device. The pressure relief piston structure is set in the borehole expansion section (29). The pressure relief piston structure includes a piston tray (5) and a metal sleeve (16). The piston tray (5) is provided with a flange for mounting bolts to be fixed to the surrounding rock (1). The flange is fixed to the surrounding rock (1) by setting tray bolts (6) and tray nuts (7). The front end of the piston tray (5) is provided with a piston head in the preset borehole. The piston head and the metal sleeve (16) are matched to form a piston structure. The metal sleeve (16) abuts against the end of the borehole expansion section (29). The pressure detection device includes a pressure nut (8), which is installed on the exposed section of the tail of the anchor rod (3) in close contact with the piston tray (5). A prestress monitoring device (13) is connected to the pressure nut (8). A pressure sensor (26) is installed inside the prestress monitoring device (13). The gas pressure inside the prestress monitoring device (13) is monitored in real time by the pressure sensor (26). All micro hydraulic jacks (19) are connected to the metal sleeve (16) through a high elongation hose (18). When the surrounding rock deforms, the surrounding rock squeezes the metal sleeve (16) outward. The piston head of the piston tray (5) moves relative to the metal sleeve (16) inside. When the pressure reaches the preset threshold, the micro hydraulic jack (19) is controlled to extend through the high elongation hose (18) to increase the force between the jack and the borehole wall of the borehole (2), thereby completing the pressure relief. When the surrounding rock deforms, it pushes the metal sleeve outward, and the piston-type tray can move inside it. The pressure testing nut (8) includes a rotating module (9), which is connected to a piston-type propulsion module (23). The piston-type propulsion module (23) is connected to a pressure transmission module (24). The pressure transmission module (24) is equipped with a rotary valve (14). The rotary valve (14) controls the pressure transmission module (24) to be connected to the pressure sensor (26) via a high-elongation hose (18). The pressure transmission module (24) is located between the piston-type propulsion module (23) and the piston tray (5). The piston-type propulsion module (23) and the pressure transmission module (24) are connected by a piston. An annular sealing rubber gasket a (11) is provided between the two to maintain a tight seal. The piston propulsion module (23) can perform piston movement in the pressure transmission module (24) and compress the gas volume in the pressure transmission module. There are multiple rotating steel balls (10) between the piston propulsion module (23) and the rotating module (9) to keep the rotating module (9) and the piston propulsion module (23) rotating freely. The rotating module (9) can rotate forward on the anchor rod (3) through the thread and push the piston propulsion module (23) to perform piston movement in the pressure transmission module (24). When the piston propulsion module (23) is compressed in the pressure transmission module (24), the gas volume is compressed. When installing, the piston propulsion module (23) needs to be stretched.

2. The prestressed, visualized, large deformation relief anchor bolt according to claim 1, characterized in that: A pressure valve (20) that can be opened after the pressure reaches a specified value is provided at the connection between the high elongation hose (18) and the metal sleeve (16). The miniature hydraulic jack (19) includes a hydraulic cylinder (31) vertically mounted on the anchor rod (3). The hydraulic cylinder (31) is provided with a force transmission rod (21) as a hydraulic rod. The end of the force transmission rod (21) is provided with a 1 / 4 annular force transmission plate (22) that matches the borehole wall structure. The outer surface of the 1 / 4 annular force transmission plate (22) is provided with multiple protruding spikes (32).

3. The prestressed, visualized, large deformation relief anchor bolt according to claim 1, characterized in that: A honeycomb-shaped elastomeric material (17) is placed inside a metal sleeve (16). The metal sleeve (16) and the end of the piston-type tray (5) are matched to form a piston and piston cylinder structure. The honeycomb-shaped elastomeric material (17) contains a hydraulic medium (27) in the gap inside the metal sleeve (16). An annular sealing rubber gasket b (15) for sealing is provided between the end of the piston-type tray (5) and the metal sleeve (16). When the surrounding rock (1) deforms, the surrounding rock (1) squeezes the metal sleeve (16) towards the piston-type tray. The disc (5) moves, thereby causing the piston-type tray (5) to deform the honeycomb elastomeric material (17) by squeezing it through the annular sealing rubber pad b (15) to release pressure. At the same time, due to the reduction of the internal space of the metal sleeve (16), the volume of the hydraulic medium (27) is compressed, and the hydraulic pressure begins to increase. When the pressure reaches the set value, the pressure valve (20) opens, allowing the hydraulic medium (27) to flow through the high elongation hose (18) to each micro hydraulic jack (19), thereby enabling the micro hydraulic jack (19) to work.

4. The prestressed, visualized, large deformation relief anchor bolt according to claim 1, characterized in that: The prestress monitoring device (13) is connected to the rotary valve (14) on the pressure transmission module (24) via a high elongation hose (18). The prestress monitoring device (13) is connected to a micro compressor to a micro air compressor (28) via the high elongation hose (18). Compressed air (12) is delivered to the prestress monitoring device (13) and the pressure transmission module (24) via the micro air compressor (28). The connection between the micro air compressor (28) and the prestress monitoring device (13) is controlled by the air inlet valve (30) set on the pressure sensor (26).

5. A prestressed, visualized, large deformation relief anchor bolt according to claim 1, characterized in that: Miniature hydraulic jacks (19) are set perpendicular to the anchor rod (3). The number of miniature hydraulic jacks (19) is arranged according to the size of the anchor rod (3). Before construction, all miniature hydraulic jacks (19) and pressure valves (20) on the metal sleeve (16) only need to be connected through the high elongation hose (18). The metal sleeve (16) and piston tray (5) are assembled during production, and the honeycomb elasto-plastic material (17) has been injected with hydraulic medium (27) during production.

6. The prestressed, visualized, large deformation relief anchor bolt according to claim 1, characterized in that: The borehole diameter of the borehole reaming section (29) is the same as that of the metal sleeve (16). The length of the borehole reaming section (29) is the sum of the radial lengths of the metal sleeve (16) and the piston tray (5). This allows the flange part of the piston tray (5) to be fixed to the surrounding rock wall by the tray bolts (6) and the tray nuts (7). The end of the piston tray (5) contacts the honeycomb elasto-plastic material (17) inside the opening of the metal sleeve (16), and the end of the metal sleeve (16) abuts against the end face of the borehole reaming section (29).

7. A method of using the prestressed visual large deformation relief anchor bolt as described in any one of claims 1 to 6, characterized in that... The steps are as follows: First, the anchoring borehole (2) is completed on the surrounding rock (1). The borehole (2) is a stepped structure. After the anchor bolt borehole is completed, the borehole enlargement section (29) is constructed. The borehole enlargement section (29) matches the size of the metal sleeve (16). A gap is left between the outer edge of the piston tray (5) and the matching part of the metal sleeve (16) and the borehole wall. After cleaning the hole, the assembled metal sleeve (16) and piston tray (5) are installed on the anchor rod (3). The pressure valve (20) and multiple miniature hydraulic jacks (19) are connected through the high elongation hose (18). Anchoring agent (4) is injected into the bottom of the borehole (2). The anchor rod (3) is placed in the borehole (2). The anchor rod (3) is rotated. The anchoring agent (4) is stirred evenly through the serrated anchoring end (25) set at the end of the anchor rod (3). The piston tray (5) is fixed on the surrounding rock (1) through the tray bolt (6) and tray nut (7). After the anchor bolt (3) is installed in place, the pressure testing nut (8) is initially installed on the exposed section of the anchor bolt (3) behind the piston tray (5). The rotary valve (14) is opened, and the piston propulsion module (23) and pressure transmission module (24) are squeezed until the air in the pressure transmission module (24) is completely discharged. The micro air compressor (28), prestress monitoring device (13) and pressure transmission module (24) are connected by the high elongation hose (18). The rotary valve (14) is closed and the air inlet valve (30) is open. Start the micro air compressor (28) to input compressed air (12) into the prestress monitoring device (13). When the reading of the prestress monitoring device (13) reaches 60~80% of its range, turn off the micro air compressor (28) to ensure that the atmospheric pressure in the prestress monitoring device (13) is within its effective range. With the air inlet valve (30) closed and the rotary valve (14) open, compressed air (12) in the prestress monitoring device (13) enters the pressure transmission module (24) through the high elongation hose (18). After the gas volume stabilizes, rotate the rotary module (9) so that the entire pressure measuring nut (8) is exactly attached to the piston tray (5), and reset the reading of the prestress monitoring device (13) to zero. Then, rotate the rotary module (9) to apply prestress to the anchor rod. Since one side of the pressure transmission module (24) is already attached to the piston tray (5), the piston propulsion module (23) is pushed along the anchor rod axis into the pressure transmission module (24) by the rotary module (9), and the pressure is transmitted. The air volume inside module (24) decreases and the air pressure increases. During this process, the prestress monitoring device (13) is connected to the pressure transmission module (24) through the high elongation hose (18). The gas pressure is obtained through the pressure sensor (26) installed in the prestress monitoring device (13), and then the real-time anchor prestress can be calculated. The reading of the prestress monitoring device (13) is the calculated anchor prestress, which can be read directly. This achieves the purpose of visualizing the anchor prestress during the application process. After the anchor prestress is applied to the design value, the rotary valve (14) is closed, and the miniature air compressor (28), the prestress monitoring device (13), and the multi-section high elongation hose (18) can be removed.

8. The method of using the prestressed visualized large deformation relief anchor bolt according to claim 7, characterized in that: When the surrounding rock (1) deforms, the borehole expansion section (29) of the surrounding rock (1) squeezes the metal sleeve (16) so that it moves relative to the piston tray (5), and then the piston tray (5) pushes the annular sealing rubber pad b (15) to squeeze the honeycomb elastic-plastic material (17) to deform and release pressure. The internal space of the metal sleeve (16) becomes smaller, the hydraulic medium (27) is compressed, and the pressure increases. When the deformation of the surrounding rock (1) continues to increase, and the pressure of the hydraulic medium (27) in the honeycomb elasto-plastic material (17) exceeds the set value, the pressure forces the pressure valve (20) to open. The hydraulic medium (27) supplies pressure to the micro hydraulic jack (19) through the high elongation hose (18). The force transmission rod (21) pushes the 1 / 4 ring force transmission plate (22) to squeeze the inner wall of the borehole (2). The protruding spikes (32) designed on the 1 / 4 ring force transmission plate (22) can penetrate into the inner wall of the borehole (2), increasing the frictional resistance between the anchor rod (3) and the borehole (2) to improve the safety and stability of the support structure.

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