Method for calculating multi-section self-expanding anchor rod of fractured rock mass and anchor rod pulling force

Abstract

The application provides a fissure rock mass multi-section self-expanding anchor rod and a method for calculating the anchor rod pulling force. The fissure rock mass multi-section self-expanding anchor rod comprises an anchoring structure, a sleeve, an expansion assembly and a moving extrusion assembly. The anchoring structure is used to contact the hole wall of the fissure rock mass. The sleeve is sleeved on the outer periphery of the anchoring structure and is in sliding connection with the anchoring structure. The sleeve is arranged in the vertical direction. The sleeve is provided with a plurality of avoiding notches. The avoiding notches are arranged at intervals around the central axis of the sleeve. The expansion assembly is provided with a plurality of expansion assemblies. Each expansion assembly is arranged in one-to-one correspondence with each avoiding notch. Each expansion assembly is arranged on the anchoring structure and in the corresponding avoiding notch. The moving extrusion assembly is arranged in sliding connection with the lower end of the sleeve on the anchoring structure. The fissure rock mass multi-section self-expanding anchor rod and the method for calculating the anchor rod pulling force can solve the technical problem of poor anchoring of the anchor rod in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of anchor bolt technology, specifically relating to a multi-segment self-expanding anchor bolt for fractured rock mass and a method for calculating the anchor bolt pull-out force. Background Technology

[0002] In the field of fractured rock mass reinforcement, anchor bolts have always been widely used as an economical and easy-to-install construction material.

[0003] In existing technologies, traditional anchor bolts often fail to anchor due to excessive stress or rock deformation, leading to detachment or cracking. Furthermore, during construction, anchor bolts are installed by drilling and grouting. During drilling, a loosening zone is created in the surrounding rock mass. The limited friction between the anchor bolt and the anchor body during grouting is insufficient to support the deformation of the surrounding rock mass, easily causing the anchor bolt to slip off and resulting in anchor bolt failure. Consequently, the anchor bolt cannot effectively perform its anchoring function and has poor practicality. Summary of the Invention

[0004] This invention provides a method for calculating the pull-out force of a multi-segment self-expanding anchor bolt in fractured rock mass, aiming to solve the technical problem of poor anchoring performance of anchor bolts in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a multi-segment self-expanding anchor bolt for fractured rock mass and a method for calculating the anchor bolt pull-out force, wherein the multi-segment self-expanding anchor bolt for fractured rock mass includes:

[0006] Anchoring structures are used to contact the borehole walls of fractured rock masses;

[0007] A sleeve is fitted around the outer periphery of the anchoring structure and slidably connected to the anchoring structure. The sleeve is arranged in a vertical direction. The sleeve is provided with a clearance groove, and there are multiple clearance grooves. Each clearance groove is spaced around the central axis of the sleeve.

[0008] Multiple expansion components are provided, each expansion component corresponding to a specific clearance slot. Each expansion component is disposed on the anchoring structure and within its corresponding clearance slot.

[0009] The movable extrusion assembly is slidably mounted on the anchoring structure and connected to the lower end of the sleeve.

[0010] In one possible implementation, the anchoring structure is arranged vertically, the anchoring structure includes an anchoring part and an anchor rod body, the anchoring part is provided with threads, the anchor rod body is located below the anchoring part, and the sleeve is fitted around the outer periphery of the anchor rod body.

[0011] In one possible implementation, each of the expansion components includes an expansion top block, and at least two expansion top blocks are provided, with each expansion top block spaced apart vertically on the anchor body.

[0012] In one possible implementation, each of the expansion top blocks has an arc-shaped structure.

[0013] In one possible implementation, the movable compression assembly includes a movable block slidably disposed on the anchor body and connected to the lower end of the sleeve.

[0014] Another object of the present invention is to provide a method for calculating the pull-out force of anchor bolts. Based on the multi-segment self-expanding anchor bolts in fractured rock masses as described above, the ultimate pull-out force of the anchor bolts is:

[0015] Where N is the number of top blocks, f is the friction coefficient, and w n S represents the actual width of the raised structure. n Let C be the elastic constant of the sleeve. n R represents the geometric parameters of the expanded top block. n Let be the radius of the expansion top block, and n be the number of expansion components.

[0016] In one possible implementation, the elastic constant S of the sleeve n The calculation formula is:

[0017] Where E is the elastic modulus of the sleeve; μ is the Poisson's ratio of the sleeve; a n b is the inner diameter of the sleeve; n The outer diameter is the sleeve.

[0018] In one possible implementation, the geometric parameter C of the expanded top block... n The calculation formula is:

[0019] Where h is the axial length of the expansion block.

[0020] The beneficial effects of the multi-segment self-expanding anchor bolt for fractured rock mass provided by this invention are as follows: Compared with the prior art, by setting an anchoring structure, the anchoring structure contacts the borehole wall of the fractured rock mass. A sleeve is fitted around the outer periphery of the anchoring structure and is slidably connected to it. The sleeve is provided with multiple clearance slots, each spaced around the central axis of the sleeve. Simultaneously, multiple expansion components are provided, each corresponding to one of the clearance slots, thus each expansion component is positioned within its corresponding clearance slot. A movable compression component is slidably mounted on the anchoring structure and connected to the lower end of the sleeve. In this application, when the fractured rock mass deforms, the movable compression component drives the sleeve to move, causing relative sliding between the sleeve and the anchoring structure. This results in compression friction between the expansion component and the sleeve, causing the sleeve to expand. The sleeve exerts a certain compressive force on the borehole wall and surrounding rock mass, preventing the anchor bolt from falling off, enhancing the anchoring effect, and improving practicality. Attached Figure Description

[0021] Figure 1 A schematic diagram of the structure of a multi-segment self-expanding anchor bolt for fractured rock mass provided in an embodiment of the present invention. Figure 1 ;

[0022] Figure 2 for Figure 1 Enlarged structural diagram at point A in the middle;

[0023] Figure 3 A schematic diagram of the structure of a multi-segment self-expanding anchor bolt for fractured rock mass provided in an embodiment of the present invention. Figure 2 ;

[0024] Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure at point B.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10. Anchoring structure; 11. Anchoring part; 12. Anchor rod body; 20. Sleeve; 21. Clearance groove; 22. Abutment end; 30. Expansion assembly; 31. Expansion top block; 40. Moving compression assembly. Detailed Implementation

[0027] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0028] It should be noted that the terms "length", "width", "height", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", and "tail" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0029] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Additionally, "multiple" and "several" mean two or more, unless otherwise explicitly specified.

[0031] Please refer to the following: Figures 1 to 4 This invention describes the multi-segment self-expanding anchor bolt for fractured rock mass and the method for calculating its pull-out force. The multi-segment self-expanding anchor bolt for fractured rock mass includes an anchoring structure 10, a sleeve 20, expansion components 30, and a movable compression component 40. The anchoring structure 10 is used to contact the borehole wall of the fractured rock mass. The sleeve 20 is fitted around the outer periphery of the anchoring structure 10 and is slidably connected to it. The sleeve 20 is arranged vertically. Multiple clearance slots 21 are provided on the sleeve 20, and each clearance slot 21 is spaced apart around the central axis of the sleeve 20. Multiple expansion components 30 are provided, each corresponding to one of the clearance slots 21. Each expansion component 30 is mounted on the anchoring structure 10 and positioned within its corresponding clearance slot 21. The movable compression component 40 is slidably mounted on the anchoring structure 10 and connected to the lower end of the sleeve 20.

[0032] The multi-segment self-expanding anchor bolt for fractured rock mass provided in this embodiment of the invention, compared with the prior art, involves setting an anchoring structure 10, which contacts the borehole wall of the fractured rock mass. A sleeve 20 is fitted around the outer periphery of the anchoring structure 10 and is slidably connected to it. The sleeve 20 has multiple clearance slots 21, which are spaced apart around the central axis of the sleeve 20. Multiple expansion components 30 are provided, each corresponding to one of the clearance slots 21, thus each expansion component 30 is positioned within its corresponding clearance slot 21. A movable compression component 40 is slidably mounted on the anchoring structure 10 and connected to the lower end of the sleeve 20. In this application, when the fractured rock mass deforms, the sleeve 20 is moved by moving the extrusion component 40. The sleeve 20 and the anchoring structure 10 slide relative to each other, thereby causing the expansion component 30 and the sleeve 20 to generate extrusion friction. The sleeve 20 expands and generates a certain extrusion force on the hole wall and the surrounding rock mass, which prevents the anchor rod from falling off, enhances the anchoring effect, and has good practicality.

[0033] In some embodiments, please refer to Figure 1 and Figure 3 The anchoring structure 10 is arranged vertically and includes an anchoring part 11 and an anchor rod body 12. The anchoring part 11 is threaded, the anchor rod body 12 is located below the anchoring part 11, and a sleeve 20 is fitted around the outer periphery of the anchor rod body 12. In this embodiment, by providing threads on the anchoring part 11, the contact area between the anchoring part 11 and the hole wall is increased.

[0034] In some embodiments, please refer to Figure 2 Each expansion component 30 includes an expansion top block 31. At least two expansion top blocks 31 are provided, each spaced vertically on the anchor body 12. In this embodiment, after grouting, as the surrounding rock deforms, the moving extrusion component 40 causes the sleeve 20 to slide relative to the anchor body 12. The abutting end 22 of the sleeve abuts against the expansion top block 31, causing extrusion friction between the expansion top block 31 and the sleeve 20. Under the extrusion friction of the lowest expansion top block 31, the sleeve 20 undergoes initial expansion, generating a certain extrusion force on the borehole wall and the surrounding rock mass. As the surrounding rock deformation deepens, the expansion top blocks 31 arranged sequentially from bottom to top contact the sleeve 20 in sequence, providing greater constant resistance, generating multiple expansions, further improving the anchoring effect, and reinforcing the loose ring of the borehole wall.

[0035] In the above embodiment, there is a certain distance between the multiple expansion blocks 31. The contact time between the expansion blocks 31 and the sleeve 20 can be controlled by controlling the distance between two adjacent expansion blocks 31, thereby changing the ultimate resistance value of the anchor bolt under different degrees of deformation of the rock mass.

[0036] In some embodiments, please refer to Figure 2Each expansion block 31 has an arc-shaped structure. Specifically, each expansion block 31 can be a semi-circular structure.

[0037] In some embodiments, please refer to Figure 2 There are two expansion top blocks 31, which can be the first expansion block and the second expansion block respectively. Both the first expansion block and the second expansion block are semi-circular structures, but the diameters of the first expansion block and the second expansion block are different. By setting multiple sets of expansion top blocks 31 of different sizes, the sleeve 20 can expand in multiple stages.

[0038] In some embodiments, please refer to Figure 1 and Figure 3 The movable compression assembly 40 includes a movable block, which is slidably disposed on the anchor rod body 12, and one end of the movable block is connected to the lower end of the sleeve 20. In this embodiment, one end of the movable block is connected to the lower end of the sleeve 20, so that the sleeve 20 and the anchor rod body 12 slide relative to each other under the action of the movable block.

[0039] Based on the same inventive concept, this application also provides a method for calculating the pull-out force of an anchor bolt. Based on the aforementioned multi-segment self-expanding anchor bolt in fractured rock mass, the ultimate pull-out force of the anchor bolt is:

[0040]

[0041] Where N is the number of top blocks, f is the friction coefficient, and w n S represents the actual width of the raised structure. n Let C be the elastic constant of sleeve 20. n R is the geometric parameter of the expanded top block 31. n Let n be the radius of the expansion top block 31, and n be the number of expansion components 30. In this embodiment, the ultimate tensile strength of the anchor bolt is controlled by changing the parameters of the expansion top block 31 structure and the control sleeve 20 structure.

[0042] In some embodiments, the anchor rod is modeled using elasticity formulas and a circular ring force model. A coordinate system z-axis is established along the central axis of the rod, with the center of the semi-circular expansion block 31 as the midpoint. The following formula can be used to calculate the radial compressive force exerted by the expansion block 31 on the sleeve 20:

[0043]

[0044] Where S n The elastic constant of sleeve 20 is given by ; h is the axial length of expansion block 31; a n Let z be the inner diameter of the sleeve (20mm); z is the independent variable of the function.

[0045] In some embodiments, to simplify the model for calculating the ultimate tensile pull-out force of the anchor bolt, it is assumed that the expansion block 31 is a regular semi-circular body and a rigid body; and that when the expansion block 31 and the sleeve 20 undergo extrusion friction, the sleeve 20 undergoes fully elastic deformation; therefore, the constitutive relation of the sleeve 20 deformation can be obtained according to the formulas of elasticity. The constitutive relation of the sleeve 20 deformation is expressed by the following calculation formula:

[0046]

[0047] Where δ(z) is the radial deformation of sleeve 20; b n Let be the outer diameter of sleeve 20; E be the elastic modulus of sleeve 20; and μ be the Poisson's ratio of sleeve 20. By refining the constitutive relationship of sleeve 20 under deformation, the radial compressive force generated by the expansion block 31 on sleeve 20 can be obtained:

[0048]

[0049] Where S n Let S be the elastic constant of sleeve 20, which is only affected by the structural parameters of sleeve 20 itself. n for:

[0050] Where E is the elastic modulus of sleeve 20; μ is the Poisson's ratio of sleeve 20; a n The inner diameter of the sleeve is 20 mm; b n The sleeve has an outer diameter of 20 mm.

[0051] In some embodiments, the radial compressive force P′(z) generated by the expansion block 31 on the sleeve 20 is distributed over an annular region R. n By integrating the axial length h of the expansion block 31 along the z-axis with radius 31, the total resistance P when any expansion block 31 and sleeve 20 experience extrusion friction can be obtained. n The total resistance P of the anchor bolt when any expansion block 31 and sleeve 20 are subjected to extrusion friction can be calculated using the following formula. n :

[0052]

[0053] From the force analysis, we get P0(z)=fP′(z)cos 2 α;

[0054] α is the angle between the tangent at any point on the expansion block 31 and the central axis of the rod; after rearranging the equation, the magnitude of the ultimate tensile force P0 of the anchor rod can be obtained as:

[0055]

[0056] The geometric parameters C of the expansion block 31 are obtained by simplifying the formula for the ultimate pull-out force. n :

[0057]

[0058] Since the magnitudes of the first two terms in the formula are much larger than those of the latter, they are neglected for the sake of simplifying the calculation. The geometric parameters C of the actual expanded top block 31 are... n : Where h is the axial length of the expansion block 31.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-segment self-expanding anchor bolt for fractured rock mass, characterized in that, include: Anchoring structures are used to contact the borehole walls of fractured rock masses; A sleeve is fitted around the outer periphery of the anchoring structure and slidably connected to the anchoring structure. The sleeve is arranged in a vertical direction. The sleeve is provided with a clearance groove, and there are multiple clearance grooves. Each clearance groove is spaced around the central axis of the sleeve. The expansion components are provided in multiple ways, and each expansion component is arranged in a one-to-one correspondence with each of the clearance slots. Each expansion component is arranged on the anchoring structure and is arranged in the corresponding clearance slot. as well as The movable extrusion assembly is slidably mounted on the anchoring structure and connected to the lower end of the sleeve; The anchoring structure is arranged vertically, and includes an anchoring part and an anchor rod body. The anchoring part is provided with threads, the anchor rod body is located below the anchoring part, and the sleeve is fitted around the outer periphery of the anchor rod body. Each of the expansion components includes an expansion top block, and at least two expansion top blocks are provided, with each expansion top block being spaced apart on the anchor body in a vertical direction; There is a certain distance between each of the expansion blocks; Each of the expansion blocks includes a first expansion block and a second expansion block. Both the first expansion block and the second expansion block have a semi-circular structure, and the diameters of the first expansion block and the second expansion block are different. Each of the aforementioned expansion top blocks has an arc-shaped structure; The movable extrusion assembly includes a movable block that is slidably disposed on the anchor body and is connected to the lower end of the sleeve.

2. A method for calculating the pull-out force of an anchor bolt, based on the multi-segment self-expanding anchor bolt for fractured rock mass as described in claim 1, characterized in that... The ultimate pull-out force of the anchor bolt is: P0 = ; Where N is the number of top blocks, and f is the friction coefficient. This is the actual width of the raised structure. Let be the elastic constant of the sleeve. For the geometric parameters of the expansion block, Let be the radius of the expansion top block, and n be the number of expansion components.

3. The method for calculating the pull-out force of an anchor bolt as described in claim 2, characterized in that, The elastic constant S of the sleeve n The calculation formula is: S n ; Where E is the elastic modulus of the sleeve; μ is the Poisson's ratio of the sleeve; a n b is the inner diameter of the sleeve; n The outer diameter is the sleeve.

4. The method for calculating the pull-out force of an anchor bolt as described in claim 3, characterized in that, The geometric parameters C of the expansion top block n The calculation formula is: C n = ; Where h is the axial length of the expansion block.

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