A tension-compression hybrid anchor bolt and its construction method

Abstract

This invention discloses a tension-compression hybrid anchor rod and its construction method in the field of anchoring construction. It includes an anchor rod body and anchor nails evenly fixed on the anchor rod body at intervals. The diameter of the anchor rod body section with anchor nails is larger than the diameter of the drill hole. This application combines mechanical and adhesive anchoring methods on the basis of self-drilling anchor rods, and overcomes the problems of low construction efficiency and low support force of existing self-drilling anchor rods. It has a simple structure, reduces construction procedures, and improves the timeliness of support.

Description

Technical Field

[0001] This invention relates to the field of anchoring construction, specifically to a tension-compression hybrid anchor rod and its construction method. Background Technology

[0002] In underground engineering projects such as tunnels, when the surrounding rock is weak, fractured, and has poor self-stability, it is difficult to achieve stable borehole formation. To address this issue, the commonly used anchor type in existing technologies is the self-drilling (post-grouting) anchor, which solves a series of problems such as anchor formation and installation in weak and fractured surrounding rock. However, it also has two significant drawbacks:

[0003] Firstly, self-drilling (post-grouting) anchor bolts are bonded anchor bolts. The bolt body comes into contact with the surrounding rock through grout. The commonly used cement grout generally takes more than 7 days to fully solidify. Therefore, before the cement grout is fully solidified, the bolt body cannot support the surrounding rock, making it difficult to achieve the desired support effect in rapidly deforming rock masses.

[0004] Secondly, self-drilling (post-grouting) anchor bolts are tension anchor bolts, and their anchoring force depends on the shear stress between the grouting body surface and the borehole wall. Because the rock mass is weak and fractured, the anchoring force is also relatively low.

[0005] The patent application with application number CN201620956111.4 discloses a multi-section variable cross-section grouting anchor. By adding a tie rod inside the grouting anchor body, a conical anchor is connected to the tie rod through a rotating shaft. The conical anchor passes through an arc-shaped opening groove. When the tie rod is subjected to outward tension, the conical anchor will be pushed outward with the rotation of the rotating shaft and embedded in the cement grout and soil around the grouting anchor body. This structure can play a better role in anchor support.

[0006] However, the aforementioned patent involves drilling before installation, which cannot solve the problem of hole collapse in soft rock and cannot provide timely support for soft rock.

[0007] Therefore, how to achieve rapid support while enhancing support force in rock formations where drilling is difficult has become an urgent problem to be solved in the field of anchoring tools and anchoring construction, based on the self-advancing construction of anchor bolts. Summary of the Invention

[0008] The purpose of this invention is to provide a tension-compression integrated hybrid anchor rod and its construction method. Targeting weak and fractured rock masses with poor self-stability, based on the traditional self-drilling grouting tension anchor rod, the anchor rod body is designed as a variable cross-section rod with a diameter larger than the borehole diameter at the end exposed in the borehole. At the same time, the opening of the rod body with the anchor nail is larger than the borehole diameter, so that the self-drilling anchor rod integrates friction and bonding and is subjected to both tension and compression. This overcomes the problem that existing anchor rods cannot achieve rapid support while enhancing support force in weak and fractured rock masses.

[0009] Because soft rock has low mechanical strength, the impact of the drill bit during drilling can easily cause the rock mass to change its original short-term stability, making the rock mass structure loose and prone to collapse. The conventional anchoring method of drilling first and then installing is difficult to implement. Moreover, because soft rock has poor water stability and significant creep characteristics, the deformation of soft rock will gradually increase over time. The longer the time, the more likely it is to produce large settlement or uneven deformation. Self-drilling anchors are tension anchors, and the magnitude of their anchoring force depends on the magnitude of the shear stress between the grout surface and the borehole wall. Due to the poor stability of soft rock, the anchoring force generated is also low. At the same time, the long setting time of the grout makes it difficult to support the rock mass in time.

[0010] The objective of this invention is mainly achieved through the following technical solutions:

[0011] A tension-compression integrated hybrid anchor bolt includes an anchor bolt body, which is a variable cross-section rod body. The diameter of the anchor bolt body increases from small to large along the direction from inside the borehole to outside the borehole, and the diameter of the portion of the anchor bolt body exposed in the borehole is larger than the borehole diameter.

[0012] The exposed side of the anchor rod can squeeze against the borehole wall to generate friction, which can provide timely support for the borehole after the anchor rod is drilled in. At the same time, it can replace the grout stop plug in the traditional self-drilling anchor rod to block the borehole opening, simplify the anchor rod structure, reduce construction procedures, and speed up the construction progress and support time.

[0013] The anchor body is provided with several wedge-shaped anchors with a cross-section of right trapezoidal shape, and the anchors can be driven into the rock and soil layer through the drill hole;

[0014] Because the grout of self-drilling anchor bolts takes a long time to solidify, and weak and fractured rock masses are easily deformed, the anchor bolts are prone to deformation before the grout solidifies and generates support force, making it difficult for them to provide good support. This technology, by making the diameter of the anchor bolt body connected to the anchor bolt larger than the borehole diameter, allows the anchor bolt to be squeezed into the rock mass, reducing the stress-bearing surface of the rock mass, concentrating stress, and generating immediate friction force due to the compression of the borehole wall, thereby generating anchoring force and achieving rapid support. At the same time, the natural solidification process of the grout between the bolt body and the borehole wall is not affected, allowing this application to generate rapid and timely support before the grout solidifies. After the grout solidifies, the friction between the grout, anchor bolt, and rock mass generates even greater anchoring force.

[0015] The anchor bolt adopts a wedge-shaped structure, which allows the anchor bolt to be fully squeezed with the rock mass and mud, and can transmit axial force and torque, improve the overall stability of the structure, and effectively prevent rock mass deformation.

[0016] Furthermore, the wedge-shaped body is a right-angled trapezoid. Due to the large angle of the trapezoidal slope, it can increase the contact area with mud and rock mass and improve the connection strength. Compared with ordinary structures, the trapezoidal structure is more robust and can withstand greater tensile and torque forces, making the overall structure of the anchor body more stable and further increasing the anchoring force.

[0017] This application adopts a variable cross-section anchor rod based on the self-drilling anchor rod, increasing the diameter of some sections of the anchor rod body to be larger than the borehole diameter. This allows the anchor rod to generate immediate support by rubbing against the borehole wall when drilling into the rock mass, which can prevent borehole collapse and deformation at the first time. In addition, this technology arranges anchor nails at intervals in the anchor rod body, so that the diameter of the anchor rod connecting the anchor nails is larger than the borehole diameter. The anchor body is subjected to both tensile and compressive forces at the same time, which can increase the anchoring force of the anchor rod.

[0018] In summary, this application, targeting soft rock, integrates mechanical and adhesive anchoring methods based on self-advancing anchoring. For weak and fractured rock and soil masses that cannot form holes on their own and have poor adhesive anchoring performance, the structure of this application can achieve rapid support and improve anchoring performance. At the same time, after the adhesive grout solidifies, its adhesive anchoring force is higher, which can better solve the problem of significant creep characteristics in soft rock.

[0019] Furthermore, the anchor body includes concave variable cross-section rod segments, concave cross-section rod segments, transition rod segments, and open cross-section rod segments distributed sequentially from inside the borehole to outside the borehole;

[0020] The cross-section of the anchor body changes from front to back. At the concave variable cross-section section, it gradually increases in size and remains smaller than the borehole diameter. At the concave cross-section section, it remains unchanged. At the transition section, it gradually increases in size until it is larger than the borehole diameter. Finally, at the open cross-section section, it remains unchanged. This makes the cross-section of the anchor body smaller at the front and larger at the back, which facilitates early drilling. At the same time, the diameter of the tail of the transition section and the open cross-section section is larger than the borehole diameter, which can support the rock mass immediately during drilling to prevent borehole collapse. While waiting for the mud to solidify normally, it plays a major supporting role for the rock mass.

[0021] The diameters of both the concave variable cross-section rod segment and the transition rod segment increase from small to large along the direction from inside the borehole to outside the borehole.

[0022] With the direction of anchor drilling as the front and the direction where the anchor is located outside the borehole wall as the rear, the cross-section of the concave variable cross-section rod segment is smaller at the front and larger at the rear. During the drilling process, the anchor can reduce the sway of the rod body and make it easier to better lock the drill bit and separate the drill rod and drill bit when the drill rod is pulled back.

[0023] The open section bar segment has openings distributed along the bar body direction, and the openings can be closed;

[0024] The open-section rod segment is a slotted rod body. After entering the borehole wall, it rubs against the entire cross-section of the borehole wall. The opening is gradually closed by compression, which can prevent the grout from overflowing from the inside of the anchor body. At the same time, because the diameter of the open-section rod segment is larger than the diameter of the borehole wall, it can also prevent the grout from seeping out from the gap between the anchor body and the rock mass. This allows the grout to maintain a certain pressure in the bonding zone to fully fill the voids in the surrounding rock. It replaces the grout stopper in the traditional anchor, simplifies the anchor structure, facilitates production, and saves costs.

[0025] Furthermore, the anchors are evenly spaced along the body of the concave cross-section bar segment, and the portion of the concave cross-section bar segment connected to the anchors is an anchored concave cross-section bar segment.

[0026] The anchors are evenly distributed around the circumference of the pole, which automatically meets the requirement of centering the pole. There is no need to set a centering device, and the spaced arrangement will also reduce the resistance when the pole is driven in.

[0027] The anchors are distributed at intervals along the concave cross-section of the rod body. After the grout has solidified, when the anchor rod is subjected to tension, the anchors will squeeze the anchor body and generate compressive stress, thereby generating a compressive stress in the anchor body and achieving the effect of improving the anchoring effect through tension and compression.

[0028] The anchor bolts are fixed at equal intervals on the concave cross-section rod segment. Since the anchor bolts are evenly distributed on the concave cross-section rod segment and the diameter of the front part of the transition rod segment is smaller than the diameter of the hole wall, the section with the diameter of the anchor bolt body cross-section larger than the diameter of the hole wall and the section with the diameter smaller than the diameter of the hole wall are both present. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a diagram illustrating the anchoring application of the anchor bolts in this application;

[0031] Figure 2 This is a schematic diagram of the anchor bolt in this application;

[0032] Figure 3 For this application Figure 2 A schematic diagram of part A in the middle;

[0033] Figure 4 This is a cross-sectional view of the open section of the rod that is not pressed against the bore wall in this application;

[0034] Figure 5 This is a cross-sectional view of the open section of the rod segment subjected to compression with the bore wall in this application;

[0035] Figure 6 This is a schematic diagram of the anchor bolt body of this application;

[0036] Figure 7 This is a cross-sectional view of the concave section bar segment of this application;

[0037] Figure 8 This is a cross-sectional view of the anchor-supported concave section bar segment of this application;

[0038] Figure 9 This is a schematic diagram of the drill bit, drill pipe, and connector of this application;

[0039] Figure 10This is a perspective view of the pad used in this application;

[0040] The names corresponding to the reference numerals in the attached drawings are as follows: 1. Anchor bolt body; 101. Concave variable cross-section rod segment; 102. Anchor nail; 103. Concave cross-section rod segment; 104. Concave cross-section rod segment with anchor nail; 105. Concave structure; 106. Transition rod segment; 107. Open cross-section rod segment; 108. Bearing ring; 2. Pad plate; 201. Wedge hole; 3. Drill bit; 4. Drill rod; 401. Threaded connection segment; 402. Impact ring; 403. Large hexagonal prism segment; 404. Small hexagonal prism segment; 5. Connector. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0042] Example:

[0043] like Figures 1-10 As shown,

[0044] A tension-compression integrated hybrid anchor bolt includes an anchor bolt body 1, wherein the anchor bolt body 1 is a variable cross-section rod body, the diameter of the anchor bolt body 1 increases from small to large along the direction from inside the borehole to outside the borehole, and the diameter of the portion of the anchor bolt body 1 exposed in the borehole is larger than the borehole diameter;

[0045] The anchor body 1 in this section can generate friction by pressing against the borehole wall. After the anchor is drilled, the borehole can be supported in time. At the same time, it can replace the grout stop plug in the traditional self-drilling anchor to block the borehole opening, simplify the anchor structure, reduce construction procedures, and speed up the construction progress and support time.

[0046] The anchor body 1 is provided with a number of wedge-shaped anchors 102 with a cross-section of right trapezoidal shape, and the anchors 102 can be driven into the rock and soil layer through the drill hole;

[0047] Because the grout of self-grooving anchor bolts takes a long time to solidify, and weak and fractured rock masses are easily deformed, the anchor bolts are prone to deformation before the grout solidifies and generates support force, making it difficult for them to provide good support. This technology, by making the diameter of the anchor bolt body 1 connected to the anchor 102 larger than the borehole diameter, allows the anchor bolt to be squeezed into the rock mass, reducing the stress-bearing surface of the rock mass, concentrating stress, and generating immediate friction force due to the compression of the borehole wall, thereby generating anchoring force and achieving rapid support. At the same time, the natural solidification process of the grout between the bolt body and the borehole wall is not affected, so that this application can generate rapid and timely support before the grout solidifies. After the grout solidifies, the friction between the grout, the anchor 102, and the rock mass generates a greater anchoring force.

[0048] The anchor 102 adopts a wedge-shaped structure, which allows the anchor 102 to be fully squeezed with the rock mass and mud, which can transmit axial force and torque, improve the overall stability of the structure, and effectively prevent rock mass deformation.

[0049] Furthermore, the wedge-shaped body is a right-angled trapezoid. Due to the large angle of the trapezoidal slope, it can increase the contact area with mud and rock mass and improve the connection strength. Compared with ordinary structures, the trapezoidal structure is more robust and can withstand greater tensile and torque forces, making the overall structure of the anchor body more stable and further increasing the anchoring force.

[0050] As one possible implementation of this application, the anchor 102 is welded to the rod body of the anchor rod 1;

[0051] As a preferred embodiment of the above implementation, the anchor 102 can be integrated with the rod body to directly eliminate the risk of unstable connection.

[0052] This application adopts a variable cross-section anchor rod based on the self-drilling anchor rod, increasing the diameter of a section of the anchor rod body to be larger than the borehole diameter. This allows the anchor rod to generate immediate support by rubbing against the borehole wall when drilling into the rock mass, which can prevent borehole collapse and deformation at the first time. In addition, this technology arranges anchor nails 102 at intervals on the anchor rod body, so that the diameter of the anchor rod connecting the anchor nails 102 is larger than the borehole diameter. The anchor body is subjected to both tensile and compressive forces, which can increase the anchoring force of the anchor rod.

[0053] In summary, this application, targeting soft rock, integrates mechanical and adhesive anchoring methods based on self-advancing anchoring. For weak and fractured rock and soil masses that cannot form holes on their own and have poor adhesive anchoring performance, the structure of this application can achieve rapid support and improve anchoring performance. At the same time, after the adhesive grout solidifies, its adhesive anchoring force is higher, which can better solve the problem of significant creep characteristics in soft rock.

[0054] Furthermore, the anchor body 1 includes concave variable cross-section rod segment 101, concave cross-section rod segment 103, transition rod segment 106 and open cross-section rod segment 107 distributed sequentially from inside the borehole to outside the borehole;

[0055] The cross-section of the anchor body 1 changes from front to back. At the concave variable cross-section section 101, it gradually increases in size and becomes smaller than the borehole diameter. At the concave cross-section section 103, it remains unchanged. At the transition section 106, it gradually increases in size until it becomes larger than the borehole diameter. Finally, at the open cross-section section 107, it remains unchanged. This makes the cross-section of the anchor body 1 smaller at the front and larger at the back, which facilitates early drilling. At the same time, the diameter of the tail of the transition section 106 and the open cross-section section 107 is larger than the borehole diameter, which can support the rock mass immediately during drilling and prevent borehole collapse. It also allows the mud to solidify normally and play a major supporting role on the rock mass.

[0056] The diameters of the concave variable cross-section rod segment 101 and the transition rod segment 106 both increase from small to large along the direction from inside the borehole to outside the borehole;

[0057] As an alternative to the above technology, the concave variable cross section 101, the concave cross section 103, and the transition section 106 are designed as an integral tapered bar.

[0058] With the direction of anchor drilling as the front and the direction of anchor rod outside the borehole wall as the rear, the cross section of the concave variable cross section 101 is smaller at the front and larger at the rear. During the drilling process, the anchor rod can reduce the shaking of the rod body and make it easier to better lock the drill bit 3 when the drill rod 4 is pulled back, so that the drill rod 4 and the drill bit 3 can be separated.

[0059] The open section bar segment 107 has openings distributed along the bar body direction, and the openings can be closed;

[0060] As a preferred embodiment of this technology, the perimeter of the cross-section of the open section rod segment 107 is equal to the length of the outer arc of the drill bit 3, so that after the drill bit 3 drills in, the diameter of the anchor rod body 1 connected thereafter is not greater than the hole diameter, and the anchor rod body 1 can directly enter the hole without being subject to rock resistance.

[0061] As one possible implementation scheme of the above solution, the length of the open section rod segment 107 is 30-50cm to prevent the rod body of the open section rod segment 107 from being too short and reducing the grouting effect, while being too long would reduce the length of the anchoring section; the arc length of the open part is 1 / 10 to 1 / 5 of the perimeter of the rod body cross section to prevent the rebound squeezing effect from being poor due to too small deformation, while if it is too large, the rod body is prone to distortion, making it difficult to fit well against the hole wall and resulting in poor grouting effect;

[0062] The open section rod segment 107 is a slotted rod body. After entering the borehole wall, it rubs against the entire cross-section of the borehole wall. The opening is squeezed and gradually closes, which can prevent the grout from overflowing from the inside of the anchor rod body. At the same time, because the diameter of the open section rod segment 107 is larger than the diameter of the borehole wall, it can also prevent the grout from seeping out from the gap between the anchor rod body 1 and the rock mass. This allows the grout to maintain a certain pressure in the bonding zone to fully fill the voids in the surrounding rock. It replaces the grout stopper in the traditional anchor rod, simplifies the anchor rod structure, facilitates production, and saves costs.

[0063] Furthermore, the anchors 102 are evenly spaced along the body of the concave cross-section rod segment 103, and the part of the concave cross-section rod segment 103 connected to the anchors 102 is an anchored concave cross-section rod segment 104.

[0064] The anchors 102 are evenly distributed along the circumference of the pole, which automatically meets the requirement of centering the pole. There is no need to set a centering device, and the spaced arrangement will also reduce the resistance when the pole is driven in.

[0065] The anchor bolts 102 are distributed at intervals along the concave cross-section rod segment 103. After the grout has solidified, when the anchor rod is subjected to tension, the anchor bolts 102 will squeeze the anchor body and generate compressive stress.

[0066] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tension-compression integrated hybrid anchor rod comprising a rod body (1), characterized in that: The anchor rod body (1) is a variable cross-section rod body, the diameter of the anchor rod body (1) increases from inside to outside of the borehole, and the diameter of the part of the anchor rod body (1) exposed outside the borehole is greater than the borehole diameter; The anchor rod body (1) is provided with a plurality of wedge-shaped anchor nails (102) with a straight trapezoidal cross section, and the anchor nails (102) can be nailed into the rock-soil layer from the borehole; The anchor rod body (1) comprises, from inside to outside of the borehole, an inner concave variable cross-section rod segment (101), an inner concave cross-section rod segment (103), a transition rod segment (106), and an open cross-section rod segment (107); The diameter of the inner concave variable cross-section rod segment (101) and the diameter of the transition rod segment (106) both increase from inside to outside of the borehole; The open cross-section rod segment (107) is provided with an opening along the rod body direction, and the opening can be closed; The anchor nails (102) are uniformly distributed on the rod body of the inner concave cross-section rod segment (103), and the part of the inner concave cross-section rod segment (103) connected with the anchor nails (102) is a rod segment with anchor nails (104); The surface of the rod body of the inner concave variable cross-section rod segment (101) and the inner concave cross-section rod segment (103) is provided with an inner concave structure (105) along the rod body direction, and the inner concave structure (105) avoids the distribution of the anchor nails (102); The inner concave structure (105) is U-shaped or V-shaped; Further comprising a backing plate (2) provided with a wedge-shaped hole (201); The anchor rod body (1) passes through the wedge-shaped hole (201) of the backing plate (2), and the backing plate (2) is located outside the borehole; The end of the anchor rod body (1) close to the backing plate (2) is provided with a bearing ring (108) with an outer convex wedge-shaped structure, the inner side of the bearing ring (108) is a conical structure, the outer side of the bearing ring (108) is a cylindrical structure, and the outer surface is a threaded structure; The bearing ring (108) and the wedge-shaped hole (201) can be mutually embedded; A drill rod (4) passes through the inside of the anchor rod body (1), one end of the drill rod (4) is connected with the bearing ring (108), and the other end of the drill rod (4) is connected with a detachable drill bit (3); The drill rod (4) is a hexagonal prism rod, one side of the drill rod (4) connected with the drill bit (3) is a small hexagonal prism segment (404), the other side of the drill rod (4) away from the drill bit (3) is a threaded connection segment (401), the part between the threaded connection segment (401) and the small hexagonal prism segment (404) is a large hexagonal prism segment (403), and the cross-sectional circumscribed circle radius of the large hexagonal prism segment (403) is greater than that of the small hexagonal prism segment (404); An impact ring (402) is arranged between the threaded connection segment (401) and the large hexagonal prism segment (403); The impact ring (402) is an inner concave structure, and the inner side of the impact ring (402) can be mutually embedded with the outer side of the bearing ring (108).

2. A tension and compression integrated hybrid anchor rod as claimed in claim 1, wherein: The threaded connection section (401) is provided with a connector (5), and the connector (5) is screw-connected with the threaded connection section (401).

3. A construction method of a tension-compression integrated hybrid anchor rod, characterized in that: The construction method of the tension-compression integrated mixed anchoring anchor rod is based on the tension-compression integrated mixed anchoring anchor rod of claim 1 or 2, and comprises the following steps: S1, assembling the anchor rod and the drilling machine; The anchor rod body (1) is inserted into the base plate (2) through the wedge-shaped hole (201), and the wedge-shaped hole (201) and the bearing ring (108) are embedded with each other; The drill rod (4) is inserted into the anchor rod body (1), and the impact ring (402) and the bearing ring (108) are embedded with each other; The drill bit (3) is connected with the small hexagonal prism section (404); One end of the connector (5) is connected with the threaded connection section (401), and the other end of the connector (5) is connected with the rotary impact drilling machine; S2, after the assembly of the anchor rod and the drilling machine is completed, the anchor rod is driven into the target rock mass: After the drill bit (30) of the anchor rod is aligned with the drilling position of the target rock mass, the rotary impact drilling machine is started, and the anchor rod is driven into the target rock mass; S3, after the anchor rod is completely driven in, grouting liquid is injected into the anchor rod: After the anchor rod is completely driven in, the rotary impact drilling machine is separated from the connector (5); A pulling force is applied at the connection between the connector (5) and the threaded connection section (401), so that the drill rod (4) and the drill bit (3) are separated, and the drill rod (4) is pulled out; The grouting pipe is connected with the bearing ring (108), and the grouting liquid is injected into the anchor rod.

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