A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and its application method

Abstract

This invention relates to the field of geological disaster prevention and control technology, and discloses a hollow anchor rod with a cutting disc for reinforcing unstable rock masses and its usage method. The anchor rod includes a rod body; the anchoring section of the rod body is equipped with a cutting disc; the cutting disc includes a main base, and several blade bases are evenly distributed along the circumference of the main base; serrated blades are rotatably mounted on the blade bases via anchor bolts; a buckle is installed on the blade bases; when all serrated blades are in the retracted position, the serrations are arranged along the circumference of the main base; a torsion member is installed at the anchor bolt; the rod body is hollow, and several grouting holes are opened in the anchoring section; a hollow connecting component is set at the end of the rod body away from the anchoring section. This design maintains the original friction between the grout and the hole wall while increasing the mechanical interlocking effect between the cutting disc and the rock and soil. Furthermore, based on the optimized anchor rod structure, these two effects mutually promote and enhance each other, significantly improving the pull-out resistance of the anchor rod and effectively enhancing its long-term performance in complex environments. It is particularly suitable for the reinforcement of unstable rock masses, slopes, and foundation pits.

Description

Technical Field

[0001] This invention relates to the field of geological disaster prevention and control technology, specifically to a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and its usage method. Background Technology

[0002] Rockfalls in the Three Gorges Reservoir area affect navigation and tourism safety. Therefore, anchor bolts are commonly used in engineering projects involving unstable rocks and slopes to reinforce soil and rock masses and ensure their stability. Typically, after the anchor hole is drilled, the anchor bolt is inserted into the hole, followed by the injection of concrete or mortar. The grout fills the space around the anchor hole and diffuses naturally according to the porosity and pressure of the surrounding medium, penetrating into the tiny cracks and pores of the soil and rock mass. Over time, once the grout has completely solidified and bonded tightly to the hole wall, it forms a robust grout body. Significant friction is generated between the grout body and the hole wall. This friction means that when external forces are applied to the anchor bolt, they are not directly borne by the anchor bolt alone. Instead, the load is distributed over a wider area of ​​the soil and rock mass through the friction between the grout body and the hole wall. This allows for a more even distribution of stress, reducing the risk of localized overload. Force is transmitted through the friction between the grout body and the hole wall, providing strong support and stability, thus achieving the reinforcement of the soil and rock mass.

[0003] To improve the pull-out resistance of anchor bolts, the most widely used method is to increase the friction between the anchor bolt or grout and the borehole wall. This can be achieved by changing the properties of the grout, but more often by improving the anchor bolt itself. For example, the anchor bolts disclosed in Chinese patents 201710164860.2, 201410014781.X, and 201680069725.3 all involve adding an expansion structure to the anchor bolt body; while the anchor bolt disclosed in Chinese patent 201721808323.9 adds barbs along the anchor bolt body to improve its pull-out resistance.

[0004] Analysis reveals that the aforementioned existing technologies essentially improve anchor performance by increasing the friction between the anchor bolt and the borehole wall. However, the increase in friction between the anchor bolt and the borehole wall is limited. First, given a fixed coefficient of friction in the borehole wall, the pull-out resistance can only be increased by increasing the compressive force exerted by the anchor bolt on the borehole wall. However, in practical engineering, the increase in compressive force is also limited. Therefore, enhancing the anchoring performance of the anchor bolt by increasing friction is not ideal. Second, under dynamic disturbances such as earthquakes, the soil and rock mass and the borehole wall may be damaged, leading to frictional failure between the anchor bolt and the borehole wall. Furthermore, due to the influence of the anchor bolt material, the expansion device may experience stress relaxation, also causing frictional failure.

[0005] Therefore, the existing method of improving anchor bolt resistance through friction cannot guarantee long-term stability. Summary of the Invention

[0006] This invention aims to provide a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and its usage method. While maintaining the original friction between the grout and the borehole wall, the anchor bolt increases the mechanical interlocking effect between the cutting disc and the rock and soil. Based on the optimized anchor bolt structure, these two effects promote and enhance each other, significantly improving the pull-out resistance of the anchor bolt and effectively enhancing its long-term performance in complex environments. It is especially suitable for the reinforcement of unstable rock masses, slopes, foundation pits, and other engineering projects.

[0007] The basic solution provided by this invention is: a hollow anchor rod for reinforcing unstable rock masses with a cutting disc, comprising a rod body; along the length of the rod body, the anchoring section of the rod body is fitted with at least one cutting disc, the cutting disc being axially aligned with the rod body;

[0008] The cutting disc includes a main base, with a plurality of blade bases evenly distributed along the circumference of the main base; serrated blades are rotatably mounted on the blade bases via anchor bolts; a latch is installed on the blade base so that when the latch engages with the tip of its rearward adjacent serrated blade, the serrated blade is subjected to a force that tends to hold the serrated blade in its retracted position; when all the serrated blades are in the retracted position, the serrations are arranged circumferentially along the main base; a torsion member is installed at the anchor bolts so that the serrated blade is subjected to an elastic biasing force that tends to hold the serrated blade in its open position.

[0009] The rod body is a hollow structure, and the anchoring section of the rod body has several grouting holes. The end of the rod body away from the anchoring section is provided with a hollow connecting component.

[0010] This invention relates to a hollow anchor bolt for reinforcing unstable rock masses with a cutting disc, and also provides a method for using the hollow anchor bolt for reinforcing unstable rock masses with a cutting disc, the method comprising:

[0011] S100, Anchor bolt preparation: Connect the anchor bolt to the equipment via the connecting assembly; all clips engage with the tips of the corresponding serrated blades to keep all serrated blades in a retracted state;

[0012] S200, the end of the anchor rod with the cutting disc is placed into the corresponding preset anchor hole, wherein all the cutting discs are inside the anchor hole;

[0013] S300: Under the control of the equipment, the anchor rod starts to rotate. The buckle rubs against the hole wall and disengages without interfering with the saw blade. The saw blade opens under the elastic bias force of the torsion component and cuts the surrounding rock and soil during the rotation and opening process. After the saw blade is fully opened, the cutting is completed and the rotation stops, so that the anchor rod mechanically engages with the rock and soil at a preset depth in the anchor hole through the corresponding saw blade of the cutting disc.

[0014] S400, grouting completed.

[0015] The working principle and advantages of this invention are as follows:

[0016] While traditional anchor bolt structures can improve pull-out resistance to some extent by enhancing friction, the improvement is very limited. More importantly, relying solely on friction not only makes it difficult to achieve a balance between pull-out resistance and anchoring force, but also leads to poor long-term performance.

[0017] This solution specifically considers the significant differences between unstable rock masses and ordinary soil and rock masses, primarily in terms of stability and potential risks. Specifically, unstable rock masses refer to rock formations located on steep slopes or cliff edges that are at risk of instability, sliding, or collapse due to natural or human factors. These rock masses exhibit high instability and destructive potential, potentially posing a serious threat to human activity areas below. Therefore, traditional anchor bolt structures that rely solely on friction to increase pull-out resistance are unsuitable for unstable rock mass scenarios. The unique geological characteristics of these unstable rock masses require more comprehensive and effective reinforcement measures to ensure their long-term stability and safety. In contrast, ordinary soil and rock masses typically have better internal homogeneity and lower risk levels, requiring less complex reinforcement techniques than those used for unstable rock masses. Therefore, when dealing with unstable rock masses, more advanced and targeted solutions must be adopted to effectively address their unique geological conditions and high-risk characteristics.

[0018] To address the shortcomings of existing technologies, this solution completely alters the relationship between the anchor bolt and the rock mass, specifically targeting the unique structure of unstable rock formations and similar soil types. An improved cutting disc cuts into the rock mass surrounding the anchor hole, embedding the disc within it. This simultaneously achieves a dual pull-out resistance effect: friction between the grout and the hole wall, and mechanical interlocking between the cutting disc and the rock / soil. Furthermore, these two pull-out resistance effects mutually reinforce each other. The mechanical interlocking further increases the grouting space around the anchor hole, while the cutting disc structure enhances the complexity of this space. Therefore, the mechanical interlocking method further improves the friction between the grout and the hole wall. Once the grout fills the increased grouting space, the friction between the grout and the hole wall further enhances the mechanical interlocking effect. Thus, under these dual pull-out resistance effects and mutually reinforcing effects, the pull-out resistance of the anchor bolt in the reinforcement of unstable rock formations is significantly increased. This effectively enhances the long-term performance of the anchor bolt in complex environments, ensuring the long-term stability of the reinforced rock and soil, guaranteeing project safety, and reducing project investment. It is particularly suitable for the reinforcement of unstable rock formations, slopes, and foundation pits. In addition, the cutting disc has a simple structure, can be mass-produced, effectively reduces manufacturing costs, and facilitates its widespread use.

[0019] During installation, no additional equipment is required. Existing drilling rigs and other equipment used in other processes can be used to complete the rotation operation. At the same time, based on the installation characteristics of anchor bolts, the designed buckles and torsion components enable convenient retraction and powerful opening of the blades. During rotation, the cutting disc quickly achieves a stable and firm mechanical engagement with the rock mass. The entire anchor bolt installation process is simple to operate and convenient to construct. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses, provided in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the cutting disc provided in an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of the cutting disc in its contracted state according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the cutting disc in the open state provided in an embodiment of the present invention;

[0024] Figure 5 This is a flowchart illustrating a method for using a hollow anchor bolt with a cutting disc to reinforce unstable rock masses, as provided in an embodiment of the present invention.

[0025] Figure 6 A comparison diagram of the stress conditions of a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and a traditional anchor bolt under the same displacement, provided in an embodiment of the present invention;

[0026] Figure 7 A comparison diagram of the force distribution of a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and a traditional anchor bolt under the same displacement, provided in an embodiment of the present invention.

[0027] The markings in the accompanying drawings of the instruction manual include: cutting disc 1, main base 11, blade base 12, serrated blade 13, anchor bolt 14, torsion member 15, buckle 16, rod 2, grouting hole 3, pad 4, nut 5, and clamp 6. Detailed Implementation

[0028] The following detailed explanation illustrates the specific implementation methods:

[0029] Example 1

[0030] The basics are as follows: Figure 1 The diagram illustrates a hollow rock mass reinforcement anchor bolt with a cutting disc, comprising a rod body 2. Along the length of the rod body 2, at least one cutting disc 1 is fitted onto the anchoring section of the rod body 2, with the cutting disc 1 axially aligned with the rod body 2. In this embodiment, all components are made of steel to ensure the rigidity and strength of the anchor bolt itself. Multiple cutting discs 1 are provided in segments along the length of the rod body 2, with the spacing between adjacent cutting discs 1 adapted to the depth of the anchor hole at the installation location and the characteristics of the soil and rock mass. In this embodiment, four cutting discs 1 are provided, spaced 500-1000 mm apart. The length occupied by all cutting discs 1 is one-quarter to one-half of the length of the rod body 2. The rod body 2 can be of uniform diameter, thereby ensuring stable engagement of the cutting discs 1 while maintaining a suitable length to ensure safe and stable rotation.

[0031] like Figure 2 The cutting disc 1 includes a main base 11, with several blade bases 12 evenly distributed around the circumference of the main base 11. A serrated blade 13 is rotatably mounted on each blade base 12 via anchor bolts 14. In this embodiment, the main base 11 has a ring structure, used to mount the cutting disc 1 onto the rod 2 and welded to the rod 2. Grooves are provided on the side of the ring around the circumference of the main base 11. Six blade bases 12 are evenly distributed, each blade base 12 including two sub-bases symmetrically distributed on both sides of the groove in the main base 11. The main base 11 and the blade bases 12 are welded together. Anchor bolts 14 pass through both sub-bases and the serrated blade 13, with the serrated blade 13 located between the two sub-bases. The serrated blade 13 has an arc shape, with serrations arranged at the end of the serrated blade 13 away from the blade base 12, i.e., the tip. The end away from the tip is connected to the anchor bolt 14. The length of the saw blades 13 is such that they do not interfere with adjacent blade bases 12 in the retracted state, meaning that all saw blades 13 belonging to the cutting disc 1 have no overlapping portions along the circumference of the main base when retracted; the length occupied by the saw teeth is two-fifths to one-half of the blade length; all the saw blades 13 are arranged circumferentially along the main base 11 in the retracted position, and the influence of the curvature of the saw blades 13 themselves on the circumferential arrangement is considered to optimize the arrangement of all saw teeth along the main base 11; the end of the saw blade 13 that is installed with the anchor bolt 14 has a mounting hole, the diameter of which is larger than the diameter of the anchor bolt 14, allowing the saw blade 13 to rotate well. The appropriate number of blade bases 12 and the reasonable structure of the saw blades 13 enable smooth rotary cutting and stable circumferential engagement of the anchor holes while ensuring both structural and cost-effectiveness.

[0032] A latch 16 is installed on the blade base 12 so that when the latch 16 is engaged with the tip of the adjacent serrated blade 13, the serrated blade 13 is subjected to a force that tends to hold the serrated blade 13 in its retracted position. When all the serrated blades 13 are held in their retracted position, the entire cutting disc 1 is in a retracted state as follows: Figure 3 As shown, where Figure 3 The arrows indicate the rearward direction, and correspondingly, the opposite direction is the forward direction. In this embodiment, the latch 16 is installed rearward of the serrated blade 13 belonging to the blade base 12. Specifically, the latch 16 has a triangular bracket with its base penetrating through the two sub-bases of the blade base 12, and the penetrating part is located rearward of the serrated blade 13 belonging to the blade base 12. The length of the latch 16 satisfies the requirement that the diameter of the circle formed by the outermost ends of all the latches on the cutting disc is slightly smaller than the diameter of the anchor hole wall, so that the latch 16 can smoothly disengage from the serrated blade 13 when rubbing against the hole wall, without interfering with the opening of the serrated blade 13.

[0033] A torsion member 15 is installed at the anchor bolt 14 to subject the serrated blade 13 to an elastic biasing force that tends to hold the serrated blade 13 in its open position. When all the serrated blades 13 are held in their open position, the entire cutting disc 1 is in the open state as follows: Figure 4 As shown. In this embodiment, the torsion member 15 is a high-strength torsion spring.

[0034] The rod 2 has a hollow structure, and the anchoring section of the rod 2 has several grouting holes 3. The end of the rod 2 away from the anchoring section is provided with a hollow connecting component.

[0035] In this embodiment, the connecting assembly includes a pad 4 with a central hole, a hollow clamp 6, and a nut 5 installed between the pad 4 and the hollow clamp 6. The clamp 6 is a square clamp with a small hole on each of its four sides, and is used to connect to equipment (such as a drilling rig). The clamp 6 and the rod body 2 are an integral unit; the square shape and the holes are designed to facilitate better connection with rotating equipment. The nut 5 and the rod body 2 are connected by a rotating connection similar to a screw. The pad 4 is clamped between the rock mass and the nut. The pad 4 and the nut 5 are common components of conventional anchor bolts, with a conventional design.

[0036] Except for one cutting disc 1 near the connecting component, the grouting holes 3 are evenly distributed above the other cutting discs 1 facing the connecting component. For better grouting, in actual engineering, the grout does not necessarily have to be injected through this hollow anchor rod; it can also be injected directly from the anchor hole.

[0037] like Figure 5 As shown, in addition to the hollow rock mass reinforcement method using the aforementioned hollow rock mass reinforcement method with cutting disc 1, a method for using the hollow rock mass reinforcement method with cutting disc 1 is also provided, the method comprising:

[0038] S100, Anchor bolt preparation, connecting the anchor bolt to the equipment via the connecting assembly; all clips 16 engage with the tips of the corresponding serrated blades 13 to keep all serrated blades 13 in a retracted state; the equipment may be a drilling rig, connected to the drilling rig via the chuck 6 to control the rotation of the anchor bolt.

[0039] S200, the end of the anchor rod with the cutting disc 1 is placed into the corresponding preset anchor hole, wherein all the cutting discs 1 are inside the anchor hole; the outermost diameter of the circle formed by all the buckles 16 belonging to each cutting disc is slightly smaller than the hole diameter, firstly to facilitate the smooth insertion of the entire device into the anchor hole, and secondly to allow the buckles 16 to collide and rub against the hole wall as soon as rotation begins, so that the blade is in a retracted state after insertion.

[0040] S300, under the control of the equipment, the anchor bolt begins to rotate. The buckle 16 rubs against the hole wall and disengages without interfering with the serrated blade 13. The serrated blade 13 gradually opens under the elastic bias force of the torsion member 15, and cuts the surrounding rock and soil during the rotational opening process. After the serrated blade 13 is fully opened, the cutting is completed, and the rotation stops, so that the anchor bolt mechanically engages with the rock and soil at a preset depth in the anchor hole through the corresponding serrated blade 13 of the cutting disc 1. After the serrated blade 13 is fully opened, the blade will no longer be able to cut the rock and soil, and the rotational resistance of the anchor bolt will be significantly reduced. At this time, the cutting is completed, and the rotation stops. The difference between the height occupied by all cutting discs 1 after being inserted into the anchor hole and the depth of the anchor hole is 100-200mm. Since the cutting discs are relatively deep in the hole, the entire rotation operation process is safe, and the rotation can be stopped in the conventional way.

[0041] S400, grouting complete. The grouting pump pushes the pre-prepared grout into the hollow rod 2 under high pressure, and then spreads to the entire anchor hole and the complex groutable space formed by the cutting disc and the soil and rock. For better grouting, in actual projects, the grout does not necessarily have to be injected through this hollow anchor rod; it can also be injected directly from the anchor hole.

[0042] like Figure 6 , 7 As shown, in order to illustrate the beneficial effects of the anchor bolts in this scheme, the force conditions of the two anchor bolts, namely a traditional anchor bolt and an anchor bolt with a cutting disc, were numerically simulated when they were pulled out to the same displacement. The shades of color in the figure represent the magnitude of the force.

[0043] Depend on Figure 6 Therefore, when the same displacement occurs, Figure 6 (b) The pull-out force that the anchor bolt with a cutting disc shown can withstand is Figure 6 (a) shows that the pull-out force of the conventional anchor bolt is 1.744 times (1.91 / 1.095≈1.744), while the pull-out force of the anchor bolt in this scheme is significantly improved.

[0044] Depend on Figure 7 Therefore, when the same displacement occurs, Figure 7 (a) shows a traditional anchor bolt where the entire length is stressed, while Figure 7 (b) shows that the anchor bolt with a cutting disc is essentially unloaded for more than 50% of its length behind the cutting disc. This means that in practical engineering, the length of this portion of the anchor bolt can be reduced, thereby reducing the amount of anchor bolt material used and lowering engineering costs. In summary, for the same displacement, the anchor bolt with a cutting disc can be more than 30% shorter than the traditional anchor bolt.

[0045] In summary, under the same displacement, the anchor bolt with an added cutting disc provides approximately 1.744 times the pull-out force of the traditional anchor bolt using 70% of its length, reducing costs while improving reliability. Similarly, it is foreseeable that the same effect will exist with multiple cutting discs.

[0046] This embodiment provides a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and its application method. It completely solves the problems of low anchoring force and weak long-term performance caused by traditional anchor bolts relying solely on friction to provide pull-out resistance. Compared with existing technologies, this solution maintains the original friction between the grout and the borehole wall while increasing the mechanical interlocking effect between the cutting disc and the soil / rock mass. Furthermore, based on the optimized anchor bolt structure, these two effects mutually enhance each other, significantly increasing the anchor bolt's pull-out resistance and effectively improving its long-term performance in complex environments. This ensures the long-term stability of the reinforced soil / rock mass, guarantees project safety, and reduces project investment. It is particularly suitable for reinforcing unstable rock masses, slopes, and foundation pits. The structure is simple, facilitating mass production, reducing costs, and the installation process is simple and convenient.

[0047] Example 2

[0048] Unlike Embodiment 1, the structure of the saw blade 13 is further designed. In this embodiment, the saw blade rotates to cut the rock and soil. In this application scenario, all saw teeth participate in the cutting in the early stage of the cutting. As the cutting progresses, the diameter of the cutting kerf gradually increases. Under the elastic bias force of the torsion member 15, the saw blade 13 gradually opens up, and the number of saw teeth participating in the cutting gradually decreases. Finally, only the tip of the saw tooth cuts the rock, and the resistance experienced by the cutting disc 1 also decreases.

[0049] For the aforementioned application scenarios, the saw blade 13 is designed by comprehensively considering the rod structure, anchor hole structure, characteristics of the rock and soil being cut, and equipment parameters. For example, it takes into account factors such as the rod diameter, the elastic modulus, cohesion, and internal friction angle of the rock and soil being cut, the diameter and depth of the anchor hole, and the rotation speed provided by the equipment, to design the blade curvature, saw tooth angle, and tooth spacing, thereby creating a saw blade structural design scheme suitable for different application scenarios.

[0050] The serrated blade arc design is to make the serrated blade 13 close as much as possible with the main base 11, so that the entire cutting disc 1 is approximately circular, which is compatible with the cylindrical structure of the rod and the anchor hole structure, making it easier to be placed into the anchor hole during construction. At the same time, it is optimized to enable the serrated blade to quickly contact the rock mass after it opens, so as to achieve rapid cutting.

[0051] Design a basic curvature, and then, for different application scenarios, combine factors such as rod diameter, elastic modulus of the rock and soil being cut, cohesion and internal friction angle, anchor hole diameter and depth, and use the following formula to correct the curvature:

[0052]

[0053] Where R is the corrected blade radian, R0 is the base radian, E is the elastic modulus of the soil / rock mass (unit: GPa), and C is the cohesion of the soil / rock mass (unit: MPa). D is the internal friction angle of soil and rock (unit: °). a D is the diameter of the anchor hole (unit: mm). r Let K be the diameter of the rod (unit: mm), and k1, k2, k3, and k4 be empirical constants.

[0054] In this embodiment, the basic arc R0 of the serrated blade 13 is π / 3, and the conventional design has 6 blades with arc adaptation.

[0055] Design a basic sawtooth tooth angle, and then modify it according to the above characteristics in different application scenarios. In this embodiment, the sawtooth is triangular, the basic sawtooth tooth angle is 45°, and the angle is corrected using the following formula:

[0056] θ = θ0 + Δθ

[0057]

[0058] Where θ is the corrected sawtooth angle, θ0 is the basic sawtooth angle, E is the elastic modulus of the soil / rock mass (unit: GPa), and C is the cohesion of the soil / rock mass (unit: MPa). K is the internal friction angle of the soil and rock (unit: °), and k5, k6, and k7 are empirical constants.

[0059] In this embodiment, the basic sawtooth angle θ0 is 45°, and the sawtooth is an isosceles triangle.

[0060] The design of the tooth spacing needs to take into account the particle size of the soil and rock, the cutting depth, and the feed rate provided by the equipment. A reasonable tooth spacing can ensure that each saw tooth works effectively during the cutting process.

[0061] S=k8×E+k9×h+k 10 ×V f

[0062] Where: S is the tooth spacing, E is the elastic modulus of the soil / rock mass (unit: GPa), h is the cutting depth (unit: mm), V f The feed rates provided to the equipment (unit: mm / min), k8, k9, k 10 This is an empirical constant.

[0063] For example: This device uses regional soil and rock samples with an elastic modulus E = 25 GPa, cohesion C = 35 MPa, and internal friction angle... Rod diameter Dr =30mm, anchor hole diameter D a =150mm, empirical constants k1=0.001, k2=0.0025, k3=0.0015, k4=0.12, k5=0.3, k6=0.1, k7=0.15. After calculation, R is 1.136rad and θ is 48.2°.

[0064] In addition, during actual use, the cutting strategy should be adjusted appropriately according to the rotational speed and feed rate provided by the equipment. For example, for harder rock and soil, a lower rotational speed and a higher feed rate can be selected; for more brittle rock and soil, the opposite is true.

[0065]

[0066] Where: N is the cutting disc rotation speed (unit: rpm), E is the elastic modulus of the soil and rock mass (unit: GPa), V f The feed rate provided to the equipment (unit: mm / min), k 11 This is an empirical constant.

[0067] Therefore, not only is the saw blade structure optimized based on actual application scenarios, but the cutting efficiency is also improved by adjusting the cutting strategy and optimizing other cutting parameters (such as the cutting disc rotation speed and feed rate). This allows the saw blade to work efficiently at different cutting stages, thereby achieving the goal of efficient cutting of rock and soil.

[0068] This embodiment provides a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses and its usage method. In specific applications, based on the hardness, particle size, brittleness coefficient of the rock and soil, as well as the dimensions of the bolt body and anchor hole, a correction formula is used to adjust the blade curvature and serration angle to ensure that the blade can work efficiently under different conditions. This embodiment provides a systematic method to optimize the design of the serrated blade, enabling it to adapt to different geological conditions and construction requirements.

[0069] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses, characterized in that, Includes a rod body; along the length of the rod body, the anchoring section of the rod body is fitted with at least one cutting disc, the cutting disc being axially aligned with the rod body. The cutting disc includes a main base, with a plurality of blade bases evenly distributed along the circumference of the main base; serrated blades are rotatably mounted on the blade bases via anchor bolts; a latch is installed on the blade base so that when the latch engages with the tip of its rearward adjacent serrated blade, the serrated blade is subjected to a force that tends to hold the serrated blade in its retracted position; when all the serrated blades are in the retracted position, the serrations are arranged circumferentially along the main base; a torsion member is installed at the anchor bolts so that the serrated blade is subjected to an elastic biasing force that tends to hold the serrated blade in its open position. The rod body is a hollow structure, and the anchoring section of the rod body has several grouting holes. The end of the rod body away from the anchoring section is provided with a hollow connecting component. The serrated blade has an arc, which increases the effect of the arc of the serrated blade itself on the circumferential arrangement of the serrations on the circumferential arrangement, based on the serrations being arranged circumferentially along the main base. The serrated blade arc design is to make the serrated blade close to the main base as much as possible, so that the entire cutting disc is approximately circular, which is compatible with the cylindrical structure of the rod and the anchor hole structure, making it easy to be inserted into the anchor hole and to quickly contact the rock mass after the serrated blade opens to achieve rapid cutting. Design a basic radius, and then adjust the radius for different application scenarios using the following formula: Where R is the corrected blade radian; R0 is the basic radian; and E is the elastic modulus of the soil and rock mass, in GPa. C Cohesion of soil and rock mass, unit: MPa; φ The internal friction angle of rock and soil, in degrees; D a Anchor hole diameter, unit: mm; D r The diameter of the rod is in mm. k 1 、k 2 、k 3 、k 4 is an empirical constant.

2. The hollow anchor bolt with cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, Along the length of the rod, the cutting discs are divided into multiple segments, and the spacing between adjacent cutting discs is adapted to the depth of the anchor hole at the installation location and the characteristics of the rock mass.

3. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, The serrations are arranged at the end of the serrated blade away from the blade base, and the total length of the serrations accounts for two-fifths to one-half of the length of the serrated blade.

4. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, When the cutting disc is in its retracted state, all the serrated blades have no overlapping portions along the circumference of the main base.

5. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, The serrated blade has an installation hole at one end where it is installed with the anchor bolt. The diameter of the installation hole is larger than the diameter of the anchor bolt.

6. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, The main base has a circular structure, and the side of the circular base is provided with grooves along the circumference of the main base.

7. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 6, characterized in that, The blade base includes two sub-bases, symmetrically distributed on both sides of the groove of the main base. An anchor bolt passes through the two sub-bases, and the serrated blade is located between the two sub-bases.

8. A hollow anchor bolt with a cutting disc for reinforcing unstable rock masses according to claim 1, characterized in that, The connecting assembly includes a pad with a central hole, a hollow clamp, and a nut mounted between the pad and the hollow clamp, wherein the hollow clamp is located away from the cutting disc.

9. A method for using a hollow anchor bolt with a cutting disc for reinforcing unstable rock masses, characterized in that, The method for reinforcing unstable rock masses using a hollow anchor bolt with a cutting disc as described in any one of claims 1-8 includes: S100, Anchor bolt preparation: Connect the anchor bolt to the equipment via the connecting assembly; all clips engage with the tips of the corresponding serrated blades to keep all serrated blades in a retracted state; S200, the end of the anchor rod with the cutting disc is placed into the corresponding preset anchor hole, wherein all the cutting discs are inside the anchor hole; S300: Under the control of the equipment, the anchor rod starts to rotate. The buckle rubs against the hole wall and disengages without interfering with the saw blade. The saw blade opens under the elastic bias force of the torsion component and cuts the surrounding rock and soil during the rotation and opening process. After the saw blade is fully opened, the cutting is completed and the rotation stops, so that the anchor rod mechanically engages with the rock and soil at a preset depth in the anchor hole through the corresponding saw blade of the cutting disc. S400, grouting completed.

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