A honeycomb-like energy-absorbing and pressure-absorbing anchor rod / anchor cable and a method for implementing the same

Abstract

The present invention discloses a honeycomb-like absorbing and yielding anchor rod / anchor cable and a method for realizing the same, which includes an anchor rod / anchor cable body and a fastening / locking device. The anchor rod / anchor cable body is composed of solid threaded cylindrical rod sections / steel strand sections at both ends and a stress-deformation coordination section in the middle; the middle stress-deformation coordination section is a honeycomb-like cylindrical rod body, and the honeycomb-like cylinder refers to an interconnected diamond grid body viewed from the surface and cross section of the column. When the surrounding rock is delaminated or dislocated, the surrounding rock generates a large tensile stress or shear force on the anchor rod / anchor cable, and the diamond-shaped hole undergoes transverse or radial plastic deformation to store a portion of the strain energy, thereby absorbing energy and achieving yielding. The present invention not only achieves dynamic coordination between the deformation of the anchor rod and the deformation of the surrounding rock, but also maintains the stability of the overall support structure, so as not to cause stress concentration in certain local locations to cause the anchor rod / anchor cable to break.

Description

Technical Field

[0001] The invention belongs to the field of mine safety, and relates to roadway or tunnel support equipment, in particular to an anchor rod or anchor cable capable of absorbing and yielding pressure, and belongs to end anchor support equipment. Background Art

[0002] With the scale of coal mines and the application of large-scale, efficient, automated and intelligent mining equipment, the shallow coal resources in most mining areas in the east (Jixi, Kailuan, Zaozhuang, Jining, Xuzhou, Huainan, etc.) are close to exhaustion, and the mining depth is gradually extended to the deep. After entering deep mining, the deep tunnels are affected by high ground stress and strong mining stress, and dynamic disasters such as rock burst occur frequently. According to incomplete statistics, more than 80% of rock burst accidents occur in mining tunnels, and rock burst prevention and control in mining tunnels has become the key to surrounding rock control. As the last barrier to rock burst protection, rock burst tunnel anti-bumping support currently uses anchor rods (cables) as the basic support, combined with shotcrete, metal brackets, pillars, grouting, filling, masonry and pressure relief. Anchor support plays an important bearing role in the entire support system and is the foundation of the entire support system. In recent years, high-strength threaded steel anchors are often used as basic support in rock burst tunnels. However, due to their low elongation, limited energy absorption capacity, and poor coordination with surrounding rock deformation, the rods often suffer from tensile and shear failure under the combined action of dynamic and static loads, which in turn causes the overall progressive failure of the anchor system. The essence of anchor tension and shear failure is that the deformation of the anchor and the surrounding rock is not coordinated, resulting in the failure of the anchor. Therefore, how to ensure the dynamic coordination between the deformation of the anchor and the surrounding rock has become one of the urgent problems to be solved in deep rock burst tunnels.

[0003] In view of the above problems, a variety of new anchor rods have been developed in the prior art to solve the problem of incoordination between the anchor rod and the surrounding rock deformation, such as:

[0004] (1) Chinese patent publication number CN105909288A discloses an anti-rockburst wave-absorbing energy-dissipating anchor rod, which can absorb stress waves generated by rock mass changes through wave-absorbing dampers, and the dampers can suppress the rupture of surrounding rocks after rock mass excavation and unloading by absorbing stress and cracking energy during the rockburst incubation process, and suppress tensile failure in the rock mass. Moreover, the anchor rod can also enhance the surrounding rock strength to a certain extent after applying pre-tightening force. However, the invention does not take into account that the destruction of the anchor rod under shear stress is also one of the main reasons for the failure of the tunnel anchor rod, and cannot achieve the circumferential coordinated deformation of the anchor rod and the surrounding rock.

[0005] (2) Chinese patent publication number CN109989778A discloses a multi-stage anchor bolt and anchoring method. The invention adopts a multi-stage anchor bolt to disperse the load, increase the anchoring force and shear resistance. When the local deformation of the anchor bolt exceeds the limit, it can automatically yield to prevent stress concentration at the anchoring point, thereby preventing anchor failure or anchor bolt breakage, and adapting to local large deformation of the surrounding rock. It adopts a multi-stage anchoring method to disperse the load, increase the anchoring force and shear resistance, but does not propose effective countermeasures when the displacement of the surrounding rock occurs in the anchoring section. The invention considers the yield of axial tensile resistance, but does not fully consider the shear yield of the annular direction.

[0006] (3) Chinese patent publication number CN113217055A discloses a segmented energy-absorbing anchor cable that adapts to the deformation of block rock mass. This invention makes full use of the tensile strength of the anchor and the shear resistance of the anchor cable to resist the large uncoordinated deformation of the rock mass. Although this invention takes into account the destruction of the anchor under shear stress, its control of the surrounding rock is the combined effect of the anchor and the anchor cable, and the shear resistance and lateral elongation of the anchor itself are not significantly improved.

[0007] (4) Chinese patent publication number CN107227967A discloses a constant resistance large deformation pressure-yielding anchor rod or anchor cable, which can be segmented and constantly resisted to yield pressure, thereby protecting the overall strength of the anchor rod or anchor cable, and having a large deformation displacement distance. The invention fully considers the tensile strength of the anchor rod (cable) and achieves the effect of graded pressure-yielding. However, it does not take into account that the breaking of the anchor rod on site is the combined effect of tensile stress and shear stress. The hollow cavity and oil cavity in the invention will bring a certain degree of complexity to the construction of the anchor rod hole, and it is difficult to avoid the problem of easy breakage caused by the inability to yield pressure when the surrounding rock undergoes shear deformation.

[0008] It can be seen from the above public documents that the existing technology pays more attention to the axial bearing capacity of anchor rods or anchor cables, and ignores the shear resistance of anchor rods or anchor cables. For underground projects under complex geological conditions such as deep burial depth and high ground stress, when there is a weak structural surface in the surrounding rock, the mutual displacement of the rock mass on both sides of the structural surface will cause the anchor rods or anchor cables passing through the structural surface to bear a large shear force. At this time, the anchor rods or anchor cables are prone to shear fracture and lose the ability to control the stability of the surrounding rock, and even induce the failure of the entire support system, which seriously threatens the safe production of coal mines. Summary of the invention

[0009] In order to improve the coordinated deformation capability of the anchor rod or anchor cable with the surrounding rock during the support process, the present invention provides a honeycomb-like pressure-absorbing and yielding anchor rod / anchor cable.

[0010] The present invention provides a method for realizing the honeycomb-like pressure-absorbing and yielding anchor rod / anchor cable.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is:

[0012] A honeycomb-like pressure-absorbing anchor rod / anchor cable, which includes an anchor rod / anchor cable body and a fastening / locking device, and is characterized in that the anchor rod / anchor cable body is composed of solid threaded cylindrical rod sections / steel strand sections at both ends and a stress-deformation coordination section in the middle; the middle stress-deformation coordination section is a honeycomb-like cylindrical rod body, and the honeycomb-like cylinder refers to an interconnected diamond grid body viewed from the surface and cross-section of the column; the two ends refer to the anchor rod anchoring section and the exposed section.

[0013] Furthermore, the middle stress-deformation coordination section is integrated with the solid threaded cylindrical rod sections / steel strand sections at both ends by welding.

[0014] Furthermore, the welding methods include but are not limited to thermite welding and high-strength aluminum alloy welding, and other welding strengths may meet the support requirements.

[0015] Furthermore, the middle stress-deformation coordination section and the solid threaded cylindrical rod sections at both ends are cast into one piece, and the casting preferably recommends the existing wax film casting method (also called melt film precision casting method).

[0016] Furthermore, the material of the honeycomb-like cylindrical rod body is preferably high-elastic steel.

[0017] The following is a detailed description of a method for achieving absorption and yielding of pressure using the above-mentioned honeycomb-like absorption and yielding anchor rod / anchor cable.

[0018] First: Drill holes in the surrounding rock to be supported according to construction requirements, install the honeycomb-shaped pressure-absorbing anchor rod / anchor cable in the drilled hole, use anchoring agent to bond the anchor rod anchoring section with the surrounding rock, tighten the exposed section of the anchor rod with a tray nut or lock it with a locking device, and apply a certain prestress to the anchor rod / anchor cable;

[0019] Second: When the surrounding rock is delaminated, the surrounding rock generates a large tensile stress on the anchor rod / anchor cable. As the surrounding rock deforms, the anchor rod / anchor cable rod body generates an axial displacement due to the large axial force. At this time, the diameter of the honeycomb-like cylindrical rod body becomes smaller due to the tension, and the diamond hole is stretched. The diamond hole stores a part of the strain energy through the plastic deformation, thereby absorbing energy. On the basis of not losing the support capacity, the tensile stress is absorbed by compressive energy, and the axial coordinated deformation effect of the anchor rod and the surrounding rock is achieved;

[0020] (2) When the surrounding rock is displaced, the honeycomb-like cylindrical rod is radially sheared, and the diamond-shaped holes inside the honeycomb-like cylindrical rod are radially deformed. A part of the strain energy is stored through the radial plastic deformation of the diamond-shaped holes, thereby absorbing energy and releasing the shear stress, thereby achieving the radial coordinated deformation effect of the anchor rod and the surrounding rock.

[0021] The honeycomb-like energy-absorbing and pressure-absorbing anchor rod (cable) provided in the present invention has the following technical effects:

[0022] 1. The honeycomb-like pressure-absorbing anchor rod (cable) of the present invention has a honeycomb-like cylindrical rod body whose diameter becomes smaller when subjected to tension, and the diamond-shaped holes are stretched to achieve pressure relief of tensile stress; when subjected to shear, the shear stress can be relieved through radial deformation of the diamond-shaped holes, thereby achieving dynamic coordination between the deformation of the anchor rod and the deformation of the surrounding rock through the plastic deformation of the diamond-shaped holes.

[0023] 2. The present invention provides a honeycomb-like pressure-absorbing anchor rod (cable), wherein the honeycomb-like cylindrical rod body is composed of a plurality of diamond-shaped holes. When subjected to dynamic load disturbances in different directions, the honeycomb-like pressure-absorbing anchor rod can adaptively deform and adjust more timely than traditional pressure-absorbing anchor rods.

[0024] 3. The honeycomb-like energy-absorbing and pressure-reducing anchor rod (cable) of the present invention can allow the surrounding rock and the supporting structure to produce a certain displacement to release part of the surrounding rock pressure and the energy accumulated under the action of dynamic load, thereby playing the role of absorbing and pressure-reducing.

[0025] For a long time, it has been difficult for technicians in this field to balance the contradiction between the deformation capacity of anchor rods or anchor cables and the stability of support structures when designing anchor rods or anchor cable structures. The characteristic of diamond structure is instability, which is easily deformed by external interference, giving people a sense of insecurity, while anchor rods or anchor cables are used for safe support. Based on these characteristics, technicians would not think of applying diamonds to anchor rod / anchor cable structures under normal circumstances. However, the inventors broke the convention and made a honeycomb-like diamond lattice mechanism using the instability characteristics of the diamond structure. Compared with the diamond structure, the diamond lattice mechanism has a smaller equivalent stiffness, so it is easier to produce uniform deformation under external loads, which not only realizes the dynamic coordination between the deformation of the anchor rod and the deformation of the surrounding rock, but also maintains the stability of the overall support structure, so as not to cause stress concentration in certain local positions to cause the anchor rod / anchor cable to break. It solves the technical problems in this field, has outstanding substantive characteristics and significant progress, and meets the creativity stipulated in Article 22, Paragraph 3 of the Patent Law. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings used in the description of the embodiment will be briefly introduced below. The drawings in the following description are only principle diagrams of an embodiment of the present invention. For ordinary technicians in this field, other similar drawings can also be obtained based on these drawings.

[0027] Figure 1 A schematic diagram of a honeycomb-like pressure-absorbing and yielding anchor provided by the present invention;

[0028] Figure 2 It is the cross-sectional view of the AA section;

[0029] Figure 3 Schematic diagram of the tensile deformation of the rod;

[0030] Figure 4 Schematic diagram of the shear deformation of the rod.

[0031] In the figure: 1-anchoring agent, 2-anchoring section solid threaded cylindrical rod, 3-anchor hole, 4-honeycomb-shaped cylindrical rod, 5-tray, 6-washer, 7-nut, 8-exposed section solid threaded cylindrical rod, 9-surrounding rock. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more specific definition of the protection scope of the present invention. These drawings are all simplified schematic diagrams, which only illustrate the basic structure and working principle of the present invention in a schematic manner.

[0033] Example 1: Taking anchor rod as an example

[0034] like Figure 1 The honeycomb-like pressure-absorbing anchor shown includes an anchor body and a fastening device, wherein the fastening device adopts a tray 5, a washer 6 and a nut 7 commonly used in the art. The anchor body consists of three sections, which are respectively called the anchoring section solid threaded cylindrical rod body 2, the exposed section solid threaded cylindrical rod body 8 and the middle force-deformation coordination section for ease of description. These three sections constitute an equal-diameter cylinder; the middle force-deformation coordination section is a honeycomb-like cylindrical rod body 4, which belongs to a three-dimensional mesh structure. The tray 5 in the first embodiment is preferably a round arch tray.

[0035] Combination Figure 1 Appearance and Figure 2 As can be seen from the cross-sectional view, the honeycomb-like shape is an interconnected diamond grid body whether viewed from the surface of the column or the cross-section of the column, and is a diamond lattice structure.

[0036] Example 2: Take anchor cable as an example

[0037] The difference between the second embodiment and the first embodiment is that the two ends of the anchor cable are cylinders composed of steel strands, and the exposed section of the anchor cable is locked with a special lock. The lock is a commonly used component in the art and will not be described in detail here.

[0038] The material of the anchor rod or anchor cable body of the present invention is preferably high elastic steel, such as 60Si2MnA elastic steel.

[0039] The honeycomb-like cylindrical rod body 4 of the present invention is cast by the currently popular wax film precision casting process. Whether it is used for anchor cables or anchor rods, the honeycomb-like cylindrical rod body 4 and the other two sections can be welded into one piece by thermite welding or high-strength aluminum alloy, as long as the welding strength meets the support requirements. When used for anchor rods, the honeycomb-like cylindrical rod body 4 can also be cast into one piece with the other two sections by the wax film precision casting process at one time, and in this case, there is no need to cast the honeycomb-like cylindrical rod body 4 separately in advance.

[0040] The overall installation method of the honeycomb-shaped energy-absorbing anchor rod of the present invention is the same as that of an ordinary anchor rod, and does not require special construction techniques in the installation method and installation process to increase the construction difficulty. The specific installation process is described below using the anchor rod as an example.

[0041] The first step: first, drill the anchor hole 3 on the surrounding rock that needs to be supported according to the design requirements, then deliver the anchor 1 to the mouth of the anchor hole 3, and then use the anchor rod of the present invention to slowly push the anchor 1 to the bottom of the anchor hole 3, wherein the exposed section of the solid threaded cylindrical rod body 8 is exposed 15 to 20 cm, and finally use a pneumatic anchor drilling rig to connect the exposed section of the solid threaded cylindrical rod body 8 to drive the anchor rod of the present invention to drill, and drive the anchoring section of the solid threaded cylindrical rod body 2 to fully stir the anchor 1, the stirring time is 1 minute, after the stirring is completed, remove the pneumatic anchor drilling rig, at this time, the installation of the anchor rod body of the present invention is completed.

[0042] Step 2: Install the tray 5, gasket 6, nut 7 and other fastening components on the free section solid threaded cylindrical rod 8, and use a torque wrench to apply pre-tightening force. At this point, the entire honeycomb-shaped pressure-absorbing anchor rod is installed, and the state after installation is as follows: Figures 1-2 shown.

[0043] The following describes the pressure-absorbing and yielding method of the honeycomb-like pressure-absorbing and yielding anchor rod of the present invention by taking roof support as an example.

[0044] Considering that the failure of anchor bolts on site is mainly caused by the delamination or displacement of the roof, the present invention can achieve the coordination of the tensile and shear stresses generated by the delamination or displacement of the roof to a certain extent. The principle of coordinated deformation and pressure absorption of the present invention is as follows:

[0045] (1) Tensile state Figure 3 As shown). When the roof movement causes delamination, the surrounding rock 9 generates a large tensile stress on the anchor rod. When the surrounding rock movement causes delamination, the surrounding rock generates a large tensile stress on the anchor rod. As the surrounding rock deforms, when the surrounding rock tension is greater than the initial prestress of the anchor rod, the anchor rod body is subjected to a large axial force and produces axial displacement. At this time, the diameter of the honeycomb-like cylindrical rod body 4 becomes smaller when it is pulled, and the diamond hole is stretched and plastically deformed, so that the tensile stress is absorbed without losing the support capacity, so as to achieve the axial coordinated deformation effect of the anchor rod and the surrounding rock.

[0046] (2) Shear state Figure 4 After the bolt is installed, when the surrounding rock 9 is displaced and the honeycomb-like cylindrical rod body 4 is radially sheared, the rhombus-shaped holes inside the honeycomb-like cylindrical rod body 4 are radially deformed to release the shear stress, thereby achieving the radial coordinated deformation effect of the bolt and the surrounding rock.

[0047] In short, the essence of the honeycomb-like pressure-absorbing anchor is to store part of the strain energy through the plastic deformation of the diamond holes, thereby absorbing energy and achieving pressure relief.

[0048] Finally, it should be noted that the innovation of the present invention mainly lies in the honeycomb structure of the free section of the anchor rod / anchor cable and its absorption and allowance method, and the focus is not on the installation method and the overall manufacturing method. The above specific implementation methods are only used to illustrate the technical solution of the present invention but not to limit it. Ordinary technicians in this field should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A honeycomb-like pressure-absorbing anchor rod / anchor cable, comprising an anchor rod / anchor cable body and a fastening / locking device, characterized in that: The anchor rod / anchor cable body is composed of solid threaded cylindrical rod sections / steel strand sections at both ends and a stress-deformation coordination section in the middle; the middle stress-deformation coordination section is a honeycomb-like cylindrical rod body, and the honeycomb-like cylinder refers to an interconnected diamond grid body viewed from the surface and cross-section of the cylinder; the two ends refer to the anchor rod anchoring section and the exposed section; the honeycomb-like cylindrical rod body is made of high-elastic steel.

2. The honeycomb-like pressure-absorbing anchor rod / anchor cable as claimed in claim 1, characterized in that: The middle stress-deformation coordination section and the solid threaded cylindrical rod sections / steel strand sections at both ends are welded into one piece.

3. The honeycomb-like pressure-absorbing anchor rod / anchor cable as claimed in claim 2, characterized in that: The welding methods include aluminothermic welding and high-strength aluminum alloy welding, and the welding strength is required to meet the support requirements.

4. The honeycomb-like pressure-absorbing anchor rod / anchor cable as claimed in claim 1, characterized in that: The middle stress-bearing deformation coordination section and the solid threaded cylindrical rod sections at both ends are cast into one piece.

5. The honeycomb-like pressure-absorbing anchor rod / anchor cable as claimed in claim 4, characterized in that: The casting is a wax film casting method.

6. A method for realizing the honeycomb-like pressure-absorbing anchor rod / anchor cable as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: First: Drill holes in the surrounding rock to be supported according to construction requirements, install the honeycomb-shaped pressure-absorbing anchor rod / anchor cable in the drilled hole, use anchoring agent to bond the anchor rod anchoring section with the surrounding rock, tighten the exposed section of the anchor rod with a tray nut or lock it with a locking device, and apply a certain prestress to the anchor rod / anchor cable; Second: When the surrounding rock is delaminated, the surrounding rock generates a large tensile stress on the anchor rod / anchor cable. As the surrounding rock deforms, the anchor rod / anchor cable rod body generates an axial displacement due to the large axial force. At this time, the diameter of the honeycomb-like cylindrical rod body becomes smaller due to the tension, and the diamond hole is stretched. The diamond hole stores a part of the strain energy through the plastic deformation, thereby absorbing energy. On the basis of not losing the support capacity, the tensile stress is absorbed by compressive energy, and the axial coordinated deformation effect of the anchor rod and the surrounding rock is achieved; Third: When the surrounding rock is dislocated, the honeycomb-like cylindrical rod is radially sheared, and the diamond holes inside the honeycomb-like cylindrical rod are radially deformed. A part of the strain energy is stored through the radial plastic deformation of the diamond holes, thereby absorbing energy, achieving the compression of the shear stress, and achieving the radial coordinated deformation effect of the anchor rod and the surrounding rock.

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