Hollow grouting anchor rod automatic centering and lapping device and working method thereof

Abstract

This invention discloses an automatic centering and overlapping device for hollow grouting anchor rods and its usage method, belonging to the field of geotechnical engineering support. It includes a high-strength connecting shell for connecting two hollow grouting anchor rods. A cross-shaped mounting plate is located in the middle of the high-strength connecting shell, between the two hollow grouting anchor rods. Four sets of retractable and extendable straightening mechanisms are respectively arranged on the cross-shaped mounting plate. Each straightening mechanism includes a lightweight moving rod that extends out of the high-strength connecting shell under grouting pressure. The end of the lightweight moving rod has an outer support plate for straightening the position of the hollow grouting anchor rod. The tail of the lightweight moving rod has a liquid driving device powered by the grout, which drives the lightweight moving rod to move under the drive of the grout. By applying grouting pressure, the automatic outer support device moves towards the surrounding rock of the borehole until it contacts the rock, achieving automatic centering.

Description

Technical Field

[0001] This invention relates to an automatic centering and overlapping device for hollow grouting anchor bolts and its working method, belonging to the field of geotechnical engineering support. Background Technology

[0002] Hollow grouting anchors are widely used in slope, foundation pit, mine roadway, and tunnel engineering. As one of the common support methods for grouting and reinforcing slopes and surrounding rock stability, hollow grouting anchors offer advantages over ordinary anchors, including convenient installation, less grout loss, and better anchoring effect. However, the shortcomings of traditional hollow grouting anchor technology cannot be ignored. For example, during drilling, the excessive length of the overall support structure of self-drilling hollow grouting anchors can cause the anchors to sway, resulting in some sections deviating from the axis. This prevents the grout from evenly covering the anchors during grouting, significantly reducing the anchoring effect. Furthermore, the connectors of hollow grouting anchors generally have relatively low strength and may break under the deformation of the surrounding rock, leading to disconnection of the hollow grouting anchor and affecting the anchor support effect.

[0003] In recent years, with the development of my country's social economy, the requirements for construction quality and safety have been continuously increasing, leading to a growing demand for more refined and reliable construction devices and methods. Currently, among the existing patents related to hollow grouting anchor bolt technology, there are still relatively few involving auxiliary devices such as hollow grouting anchor bolt connectors. However, the hollow area of ​​the hollow grouting anchor bolt cross-section is large and its strength is limited. Therefore, improving the reliability of auxiliary equipment such as anchoring devices and connecting devices is equally crucial. For example, CN115182763A discloses a mortar anchor bolt drilling device that can directly fill the gap between the anchor bolt and the anchor hole with mortar while drilling the hollow grouting anchor bolt into the surrounding rock; CN207878461U utilizes grouting pressure to push out the support column to prevent the bolt from bending and sinking; CN217632520U proposes an automatic self-aligning device suitable for hollow grouting anchor bolt connectors with lower strength requirements. Currently existing hollow grouting anchor bolt connection devices suffer from problems such as low device strength and high production costs, and there is still considerable room for improvement in economic efficiency. Therefore, effective solutions are needed to address the issues of how traditional hollow grouting anchors can balance functionality and strength. There is an urgent need to develop a low-cost, high-strength, well-connected, and easy-to-operate hollow grouting anchor centering connection device. Summary of the Invention

[0004] Technical Problem: To address the shortcomings of existing technologies and overcome the deficiencies of traditional hollow grouting anchor connection devices, such as low strength and poor alignment, this paper provides an automatic alignment and overlapping device for hollow grouting anchors and its working method. This device can automatically align the hollow grouting anchor with the installation borehole, which is beneficial for load transfer and allows the hollow grouting anchor to fully utilize its load-bearing capacity, thereby improving the reliability of the support. It has advantages such as safe use, convenient installation, reliable technology, and good economic benefits.

[0005] Technical Solution: To achieve the above technical objectives, the present invention provides an automatic centering and overlapping device for hollow grouting anchor rods, used in conjunction with two hollow grouting anchor rods. It includes a high-strength connecting shell for connecting the two hollow grouting anchor rods. The inner diameter of the high-strength connecting shell matches the outer diameter of the hollow grouting anchor rod. A cross-shaped mounting plate is provided on the cross-shaped mounting plate at the cross-section between the two hollow grouting anchor rods. Four sets of straightening mechanisms pointing in four directions and capable of extension and retraction are respectively provided on the cross-shaped mounting plate. Each straightening mechanism includes a lightweight movable rod that extends out of the high-strength connecting shell under grouting pressure. The end of the lightweight movable rod... The unit is equipped with an external support plate to straighten the position of the hollow grouting anchor rod. The high-strength connecting shell has an opening at the position where the lightweight moving rod extends. A leak-proof damping washer is provided between the lightweight moving rod and the high-strength connecting shell. The tail of the lightweight moving rod is equipped with a liquid drive device that is powered by the grouting slurry. The liquid drive device drives the lightweight moving rod to move and center under the drive of the slurry, thereby ensuring that the hollow grouting anchor rod is aligned with the axis of the installation borehole before the slurry solidifies during grouting. This prevents the hollow grouting anchor rod from bending inside the installation borehole and coming into contact with the surrounding rock of the borehole wall, which would result in the slurry not completely covering the hollow grouting anchor rod and causing poor grouting reinforcement effect.

[0006] Furthermore, the cross-shaped mounting plate is provided with four rows of protruding steps to assist the movement of the four lightweight moving rods; the liquid drive device includes a miniature hydraulic fan located on the side of the cross-shaped bracket and driven to rotate directionally by the flowing slurry, the miniature hydraulic fan is coaxially connected to a small gear, the small gear is connected to a transmission gear through a metal chain, the transmission gear is coaxially connected to a climbing gear meshing on a row of protruding steps, and the lightweight moving rods move along the protruding steps through the climbing gear.

[0007] Furthermore, the front and rear sleeves of the high-strength connecting shell are respectively connected to the hollow grouting anchor rods, which are divided into front and rear sections, by threads.

[0008] Furthermore, the miniature hydraulic fan is located at the inner end of the lightweight moving rod. The blades of the miniature hydraulic fan have an arc that ensures its directional rotation under grouting pressure, thereby ensuring that the lightweight moving rod extends outward from the high-strength connecting shell. Since the miniature hydraulic fans in the four sets of straightening mechanisms on the cross-shaped mounting plate are driven by the same grouting pressure, the lightweight moving rods in the four sets of straightening mechanisms pointing in four directions extend outward at the same speed and with the same force, thereby ensuring the centering of the hollow grouting anchor rod. After grouting is completed, due to the lack of continuous power from the injected grout, the lightweight moving rod retracts slightly in the absence of continuous power, avoiding obstruction when the hollow grouting anchor rod needs to be moved. The rotation path of the miniature hydraulic fan is fixed and passes perpendicularly through the plane of the cross-shaped mounting plate structure. The base of the miniature hydraulic fan is equipped with a small gear with the same rotating shaft. The small gear is linked to the transmission gear through a metal chain. The transmission gear rotates coaxially with the climbing gear.

[0009] A method for operating an automatic centering and overlapping device for hollow grouting anchor bolts, comprising the following steps:

[0010] Drilling is carried out using a drilling rig and a diamond wear-resistant rock-breaking drill bit. After drilling is completed, the two hollow grouting anchor rods are connected by a high-strength connecting shell with an automatic centering and overlapping device.

[0011] Only by placing hollow grouting anchors equipped with automatic centering and overlapping devices into the borehole and connecting them to the grouting equipment, and then grouting through the hollow grouting anchors, can the position of the lightweight moving rod be adjusted by using the grout to drive a micro hydraulic fan, thereby automatically centering the hollow grouting anchors within the installation borehole. This ensures the accuracy of the drilling direction during construction and avoids situations where the hollow grouting anchors are not parallel to the installation borehole or even bend excessively during drilling and grout solidification. It also prevents the failure of the grouting anchor support due to excessive shear stress and bending moment, which has significant practical engineering implications.

[0012] Furthermore, during grouting, a preset grouting pressure is maintained at a constant level. The grout pressure injected into the hollow grouting anchor increases at the cross baffle inside the high-strength connecting shell. The increased flow rate accelerates the rotation of the micro hydraulic fan. The rotation of the micro hydraulic fan drives the small gear on its base to rotate. The small gear transmits the rotation of the gear and the climbing gear through a metal chain. Since the climbing gear meshes with the protruding step, the climbing gear will drive the lightweight moving rod and the outer support plate to move relative to the high-strength connecting shell. If the hollow grouting anchor deviates from the centerline position, the continuously provided grouting pressure will cause the outer support plate in the deviated direction to contact the surrounding rock of the borehole wall first and transmit the interaction force. Since the arc surface of the outer support plate has a large contact area with the surrounding rock of the borehole wall, the hollow grouting anchor is subjected to greater lateral pressure, which will cause it to shift until it automatically centers and balances in the installation borehole, so that the hollow grouting anchor always remains in the center position in the borehole during the grouting process.

[0013] Furthermore, after grouting is completed, the lightweight movable rod retracts slightly after losing power. Under the force of external machinery, the drill bit at the front end of the first hollow grouting anchor rod drills to form an installation hole. The depth of the first installation hole is approximately the length of the first hollow grouting anchor rod. If the drilling depth is to be increased, the first hollow grouting anchor rod needs to be partially pulled out so that the rear end of the first anchor rod can be installed outside the hole, thereby increasing the drilling depth. During this process, the hollow grouting anchor rod needs to move repeatedly in the hole to achieve deep drilling. Considering that high-pressure water may be applied to clean the inside of the hole during drilling, the mobility of the lightweight movable rod is retained. When there is no water pressure or grouting pressure, the lightweight movable rod naturally retracts, avoiding obstruction to the movement of the hollow grouting anchor rod.

[0014] Beneficial effects: This device can effectively achieve automatic alignment of hollow grouting anchors with installation boreholes. Its installation is relatively simple and the alignment speed is fast. During construction, a hollow grouting anchor can be screwed into each end of each high-strength connecting shell. Overlapping multiple hollow grouting anchors increases the depth of the installation borehole. The high-strength connecting shell material has a slightly higher strength than the hollow grouting anchor material, increasing the overall reliability of the support. After applying a constant grouting pressure, the grout pressure briefly increases at the cross baffle inside the device, increasing the grout flow rate and raising the speed of the micro hydraulic fan. This allows the fan to react quickly and move the lightweight moving rod outwards. The high-strength connecting shell protrudes outwards in the middle, providing more internal space and expanding the movable range of the lightweight moving rod. The adjustable range allows it to adapt to different installation borehole diameters; the damping washer prevents grout from flowing out of the gap between the lightweight moving rod and the high-strength connecting shell, and provides resistance to prevent the lightweight moving rod from shifting inward due to vibration; when the hollow grouting anchor rod experiences axial displacement due to borehole vibration, the outer support plate closest to the borehole wall rock first contacts the borehole wall rock, and part of the grouting pressure is converted into the supporting force of the outer support plate; the curved surface of the outer support plate increases its contact area with the borehole wall rock, avoiding indentation of the borehole wall rock during alignment, reducing the loss of supporting force, and improving the alignment efficiency of the rod. Its simple structure, easy operation, high connection strength, and good alignment effect make it widely applicable in this technical field. Attached Figure Description

[0015] Figure 1 A schematic diagram of the internal structure of the automatic centering and overlapping device for hollow grouting anchors in this embodiment of the invention;

[0016] Figure 2 A schematic diagram showing the working details of the climbing gear in an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the hollow grouting anchor bolt overlap in an embodiment of the present invention;

[0018] Figure 4 A schematic diagram illustrating the usage method of the automatic centering and overlapping device for hollow grouting anchor bolts in this embodiment of the invention.

[0019] In the diagram: 1-Hollow grouting anchor, 2-Installation borehole, 3-Borehole wall surrounding rock, 4-Metal chain, 5-Lightweight moving rod, 6-Transmission gear, 7-High-strength connecting shell, 8-Miniature hydraulic fan, 9-Protruding step, 10-Damping washer, 11-Outer support plate, 12-Small gear, 13-Climbing gear. Detailed Implementation

[0020] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings:

[0021] like Figure 1As shown, the automatic centering and overlapping device for hollow grouting anchor bolts of the present invention includes a hollow grouting anchor bolt 1, an automatic external support device composed of a lightweight moving rod 5, several gears, a miniature hydraulic fan 8, and an external support plate 11, and a high-strength connecting shell 7, as shown. Figure 1 As shown, the surface thread of the hollow grouting anchor rod 1 matches the inner thread of the high-strength connecting shell 7. The surface of the high-strength connecting shell 7 has four protruding parts with holes and damping sealing rings 10, and contacts the lightweight moving rod 5 through the damping sealing rings 10. The inner side has a cross baffle structure and a protruding step 9. The protruding step 9 meshes with the climbing gear 13 on the lightweight moving rod 5. One end of the lightweight moving rod 5 extends out of the high-strength connecting shell 7 and connects to the outer support plate 11. The other end inside the high-strength connecting shell 7 is equipped with a climbing gear 6 and a miniature hydraulic fan 8.

[0022] like Figure 2 As shown, the size of the damping sealing ring 10 matches that of the lightweight moving rod 5. The lightweight moving rod 5 fits into the cross baffle structure inside the high-strength connecting shell 7. The miniature hydraulic fan 8 is located at the inner end of the lightweight moving rod 5. The blades of the miniature hydraulic fan 8 have a certain curvature. Its rotation path is fixed and passes vertically through the plane where the cross baffle structure is located. The base of the miniature hydraulic fan 8 is equipped with a small gear 12 with the same rotating shaft, and is linked to the transmission gear 6 through the metal chain 4. The transmission gear 6 rotates coaxially with the climbing gear 13.

[0023] The high-strength connecting shell 7 has threads on its inner side, which can connect and fix two hollow grouting anchor rods 1. The thickness of the protruding part on the surface of the high-strength connecting shell 8 remains unchanged. The extension distance of the lightweight moving rod 5 inside is greater than the distance between the outer support plate 11 and the surrounding rock 3 of the hole wall. The cross baffle structure inside the high-strength connecting shell 7 is close to the side of the installation borehole 2.

[0024] Specific construction steps:

[0025] Step 1: Place the hollow grouting anchor rod on the drilling machine, install the diamond wear-resistant rock-breaking drill bit at the end of the hollow grouting anchor rod, and begin drilling.

[0026] Step two, combined Figure 3 As shown, after drilling to a certain depth, another hollow grouting anchor rod is screwed in through the corresponding thread, so that the two hollow grouting anchor rods 1 are fixed to the high-strength connecting shell 7. The hollow grouting anchor rods are then overlapped and drilled in sequence, thereby increasing the installation drilling depth.

[0027] Step 3, combined Figure 1 , Figure 2 , Figure 4As shown, during grouting, the pressure is kept constant. The grout pressure injected into the hollow grouting anchor rod 1 increases at the cross baffle inside the high-strength connecting shell 7, and the increased flow rate accelerates the rotation of the micro hydraulic fan 8. The rotation of the micro hydraulic fan 8 drives the small gear 12 coaxially on its base to rotate. The small gear 12 transmits the rotation of the gear 6 and the climbing gear 13 through the metal chain 4. Since the climbing gear 13 meshes with the protruding step 9, the climbing gear 13 will drive the lightweight moving rod 5 and the outer support plate 11 to move relative to the high-strength connecting shell 7. If the hollow grouting anchor rod 1 deviates from the centerline position, the continuously provided grouting pressure will cause the outer support plate 11 in the direction of deviation to contact the surrounding rock 3 of the borehole wall first and transmit the interaction force. Since the arc-shaped surface of the outer support plate 11 has a large contact area with the surrounding rock of the borehole wall, the hollow grouting anchor rod 1 is subjected to greater lateral pressure and will shift until it automatically re-aligns and balances.

[0028] The specific embodiments described above are merely illustrative or explanatory of the principles of the present invention and do not constitute a limitation thereof.

Claims

1. An automatic centering and overlapping device for hollow grouting anchor bolts, characterized in that: The application relates to a hollow grouting anchor rod (1) matching device, which comprises a high-strength connecting shell (7) used for connecting front and rear hollow grouting anchor rods (1), the inner diameter of the high-strength connecting shell (7) matches the outer diameter of the hollow grouting anchor rod (1), a cross-shaped mounting plate is arranged on the section of the high-strength connecting shell (7) between the front and rear hollow grouting anchor rods (1), four groups of righting mechanisms pointing to four directions and capable of stretching and contracting are arranged on the cross-shaped mounting plate, the righting mechanism comprises a light movable rod (5) capable of stretching out of the high-strength connecting shell (7) under the action of grouting pressure, an outer supporting plate (11) for righting the position of the hollow grouting anchor rod (1) is arranged at the end of the light movable rod (5), the high-strength connecting shell (7) is provided with an opening at the position where the light movable rod (5) stretches out, a leakage-proof damping washer (10) is arranged between the light movable rod (5) and the high-strength connecting shell (7), a liquid driving device is arranged at the tail of the light movable rod (5) and is driven by grouting liquid to move and center the light movable rod (5), so that the hollow grouting anchor rod (1) can be kept in alignment with the axis of the installation bore (2) before the grouting liquid solidifies during grouting, and the hollow grouting anchor rod (1) is prevented from being bent in the installation bore (2) and being in contact with the wall rock, so that the grouting liquid cannot completely wrap the hollow grouting anchor rod (1) and the grouting reinforcement effect is poor; Four rows of convex steps (9) are arranged on the cross-shaped mounting plate and used for assisting the movement of the four light movable rods (5); the liquid driving device comprises a micro hydraulic fan (8) arranged on the side of the cross-shaped mounting plate and driven by flowing grouting liquid to rotate, the micro hydraulic fan (8) is coaxially connected with a small gear (12), the small gear (12) is connected with a transmission gear (6) through a metal chain (4), the transmission gear (6) is coaxially connected with a climbing gear (13) engaged with the convex steps (9), and the light movable rod (5) moves along the convex steps (9) through the climbing gear (13). The micro hydraulic fan (8) is located at the inner end of the light moving rod (5), the fan blade of the micro hydraulic fan (8) has an arc to ensure its directional rotation under the grouting pressure, so as to ensure that the light moving rod (5) extends outward to the high-strength connecting shell (7), because the micro hydraulic fan (8) in the four groups of righting mechanisms on the cross-shaped mounting plate is driven by the same grouting pressure, the speed and force of the light moving rod (5) extending outward in the four groups of righting mechanisms pointing to four directions are the same, so as to ensure that the hollow grouting anchor rod (1) is centered; after grouting is completed, the light moving rod (5) retracts a small amount under the condition of lacking continuous power, which avoids hindering when the hollow grouting anchor rod (1) needs to be moved; the rotation path of the micro hydraulic fan (8) is fixed and vertically passes through the plane where the cross-shaped mounting plate structure is located, the base of the micro hydraulic fan (8) is provided with a small gear (12) with the same rotating shaft, the small gear (12) is linked with the transmission gear (6) through the metal chain (4), and the transmission gear (6) rotates coaxially with the climbing gear (13).

2. The automatic centering and splicing device for hollow grouting anchor rods according to claim 1, characterized in that: The front and rear pipe sleeves of the high-strength connecting shell (7) are respectively connected with the hollow grouting anchor rod (1) divided into front and rear two sections through threads.

3. A working method of the automatic centering and splicing device for hollow grouting anchor rods according to any one of claims 1-2, characterized in that The steps are as follows: Drilling is carried out by using a drilling machine and a diamond wear-resistant rock breaking drill bit, after drilling is completed, the high-strength connecting shell (7) of the automatic centering and lapping device is used to connect the front and rear two sections of the hollow grouting anchor rod (1); The hollow grouting anchor rod (1) provided with the automatic centering and lapping device is placed in the drilling hole and connected with the grouting equipment, grouting is carried out through the hollow grouting anchor rod (1), the grouting pressure is maintained, the micro hydraulic fan (8) is driven by the slurry to adjust the position of the light moving rod (5), so that the hollow grouting anchor rod (1) is automatically centered in the installation drilling hole (2), so as to ensure the accuracy of the drilling direction in construction, and the situation that the hollow grouting anchor rod (1) is not parallel to the installation drilling hole (2) or even the rod body is excessively bent is avoided when drilling and slurry solidification, the grouting anchor rod support failure caused by excessive shear stress and bending moment of the hollow grouting anchor rod (1) is prevented, and good practical engineering significance is achieved.

4. The method of working according to claim 3, characterized in that: When grouting, the grout pressure inside the hollow grouting anchor rod (1) will increase at the cross baffle inside the high-strength connecting shell (7), and the increase in flow rate accelerates the rotation of the miniature hydraulic fan (8). The rotation of the miniature hydraulic fan (8) drives the rotation of the small gear (12) coaxial with its base. The small gear (12) transmits the rotation of the gear (6) and the climbing gear (13) through the metal chain (4). Since the climbing gear (13) is engaged with the protruding step (9), the climbing gear (13) will drive the relative movement of the light moving rod (5) and the outer support plate (11) with the high-strength connecting shell (7). If the hollow grouting anchor rod (1) deviates from the centerline position, the continuously provided grouting pressure will cause the outer support plate (11) in the deviation direction to first contact the hole wall surrounding rock (3) and transmit the interaction force. Since the curved surface of the outer support plate (11) has a large contact area with the hole wall surrounding rock, the hollow grouting anchor rod (1) is subjected to greater lateral pressure, which will displace until it is automatically centered and balanced in the installed borehole (2), so that the hollow grouting anchor rod (1) always remains in the centered position in the borehole during grouting.

5. The method of working according to claim 3, characterized in that: After grouting is completed, the light moving rod (5) retracts a small amount after losing power; under the external machine force, the drill bit at the front end of the first hollow grouting anchor rod (1) drills into the installed borehole (2), and the depth of the first drilled installed borehole (2) is approximately the length of the first hollow grouting anchor rod (1); if you want to continue to increase the drilling depth, you need to partially withdraw the first hollow grouting anchor rod (1) so that the rear end of the first anchor rod can be installed with the next anchor rod outside the borehole, thereby achieving the increase of the drilling depth; during this process, in order to realize deep drilling, the hollow grouting anchor rod (1) needs to be repeatedly moved in the borehole; considering that high-pressure water may be applied during drilling to clean the inside of the borehole, the light moving rod (5) is kept active. When there is no water pressure or grouting pressure, the light moving rod (5) naturally retracts, avoiding hindering the movement of the hollow grouting anchor rod.

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