Anti-shearing anchor rod supporting structure for roadway with small coal pillars

Abstract

The utility model relates to the technical field of mine roadway supporting, and discloses an anti-shearing anchor rod supporting structure for a roadway with small coal pillars, which comprises an anchor rod body, a drum-shaped anti-shearing structure is arranged on the outer wall of the middle section of the anchor rod body, the drum-shaped anti-shearing structure comprises a boss fixedly connected to the outer wall of the middle section of the anchor rod body, and a plurality of tooth grooves are formed in the outer wall of the boss. The middle section of the anchor rod body is provided with a drum-shaped anti-shearing structure, the outer wall of the boss is provided with a plurality of tooth grooves, the tooth grooves are uniformly distributed in a circumferential array at equal intervals, one end of the anchor rod body is provided with an anchoring end, and the other end of the anchor rod body is provided with a free end. Therefore, the shearing resistance of the anchoring section of the anchor rod is improved, the shearing force generated by horizontal stress can be effectively resisted, the middle of the anchor rod is prevented from being subjected to shearing damage, the supporting effect of the anchor rod and the stability of a roadway are greatly improved, the fracture risk of the anchor rod is reduced, and the safety of the roadway is guaranteed.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of mine roadway support, in particular to a small coal pillar roadway shearing-resistant anchor rod support structure. BACKGROUND

[0002] In the mining of a mine roadway, the side corner area of a small coal pillar is often in a complex environment of high ground stress and broken surrounding rock, and the stress concentration characteristics of the small coal pillar and the structural defects of the broken surrounding rock synergize to form a strong damage load mode dominated by horizontal shearing force.

[0003] Under this environment, the traditional vertically arranged anchor rod exposes multiple technical problems: on the one hand, the shearing resistance of the anchor rod body is insufficient, and the middle part of the rod body is prone to become a shearing weak surface under the action of horizontal stress, which causes fracture failure, leading to frequent support failure and seriously affecting the stability of the roadway; on the other hand, the contact friction resistance between the broken surrounding rock and the tray is limited, the transverse displacement of the anchor rod is significant after being loaded, the pre-tightening force rapidly decays, it is difficult to form sustained constraint on the surrounding rock, and the active support efficiency is greatly weakened. In addition, the vertical arrangement of the bottom corner anchor rod has low matching degree with the transmission direction of the horizontal stress, and the adaptability of the stress transmission path is insufficient, which cannot effectively disperse the shearing load, leading to deformation of the side corner area exceeding the limit, and significantly increasing the maintenance cost and safety risk in the later period. Therefore, the small coal pillar roadway shearing-resistant anchor rod support structure is proposed to solve the above problems. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims at providing a small coal pillar roadway shearing-resistant anchor rod support structure to solve the problems in the background art.

[0005] The small coal pillar roadway shearing-resistant anchor rod support structure provided by the application adopts the following technical scheme:

[0006] A small coal pillar roadway shearing-resistant anchor rod support structure, comprising an anchor rod body, a drum-shaped shearing-resistant structure is arranged on the outer wall of the middle section of the anchor rod body, the drum-shaped shearing-resistant structure comprises a boss fixedly connected to the outer wall of the middle section of the anchor rod body, a plurality of tooth grooves are formed in the outer wall of the boss, and the plurality of tooth grooves are evenly distributed in an equidistant circumferential array.

[0007] One end of the anchor rod body is provided with an anchoring end, and the other end is provided with a free end, the outer wall of the free end is provided with a thread, a tray is sleeved on the outer wall of the free end, a nut is connected to the outer wall of the free end in a threaded manner, the nut is located above the tray, and a limit snap ring is sleeved on the outer wall of the anchor rod body close to the free end.

[0008] Preferably, the limit snap ring is a 10mm-thick Q345B steel ring, and is in interference fit with the anchor rod body, the limit snap ring is embedded in a groove with a depth of 20mm in the surface of the surrounding rock, and is located between the tray and the surrounding rock.

[0009] Preferably, the diameter of the boss is half of the length of the anchor rod body, and the plurality of tooth grooves are regularly distributed, and the depth and spacing are adapted to the characteristics of the anchoring agent to enhance the biting effect.

[0010] Preferably, the anchoring end comprises an expansion block, a fixing ring and a pressing block, the pressing block is fixedly connected to one end of the anchor rod body away from the free end, the pressing block is tapered, the fixing ring is sleeved on the outside of the anchor rod body, a plurality of pressing blocks are fixedly connected to the inner wall of the fixing ring, and the end of the plurality of expansion blocks away from the fixing ring abuts against the outer wall of the pressing block.

[0011] Preferably, the anchoring end is inclined to the vertical direction of the roadway side by 15-20°, and forms an angle of 30-45° with the horizontal stress direction.

[0012] In summary, the present application has the following beneficial technical effects:

[0013] 1. By providing a drum-shaped shear-resistant structure in the middle section of the anchor rod body, the outer wall of the boss is processed with a plurality of tooth grooves, the depth and spacing of which are optimized to strengthen the mechanical biting effect with the anchoring agent, and increase the contact area with the resin anchoring agent, which improves the shear resistance of the anchoring section of the anchor rod, effectively resists the shear force generated by the horizontal stress, prevents shear failure of the anchor rod in the middle section, greatly improves the supporting effect of the anchor rod and the stability of the roadway, reduces the risk of breakage of the anchor rod, and ensures the safety of the roadway.

[0014] 2. The limiting snap ring 303 of the structure is a 10mm thick Q345B steel ring, the inner diameter is in interference fit with the anchor rod body 1, the outer diameter is 80mm and is embedded in a 20mm deep groove on the surface of the surrounding rock, and cooperates with the tray to effectively limit the transverse displacement of the anchor rod body 1, significantly reduces the displacement, avoids the attenuation of the pre-tightening force due to excessive displacement, and enables the anchor rod to continuously and stably support the surrounding rock, thereby prolonging the effective supporting time.

[0015] 3. The anchor rod of the bottom corner (anchoring end) of the side of the structure is inclined to the vertical direction of the roadway side by 15-20°, and forms an angle of 30-45° with the horizontal stress direction. This inclined arrangement optimizes the stress transmission path, significantly converts the horizontal shear force into axial tension of the anchor rod, and disperses the remaining load to the surrounding rock in the form of transverse pressure, forming a collaborative shear mode of "rod body tension-resisting-surrounding rock compression", significantly reducing the risk of pure shear failure of the rod body, enabling the anchor rod to better withstand stress, effectively reducing the convergence of the side, reducing the degree of deformation of the roadway, thereby reducing the maintenance cost of the roadway, improving the safety of the roadway, and reducing safety hazards. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a whole schematic diagram of the application embodiment;

[0017] Figure 2 is a schematic diagram of an explosion of the application embodiment;

[0018] Figure 3 is a schematic diagram of a first part structure of the application embodiment;

[0019] Figure 4 is a schematic diagram of a second part structure of the application embodiment;

[0020] Figure 5 is Figure 2 is an enlarged schematic diagram of the structure at A in the middle.

[0021] Reference signs: 1, anchor rod body; 2, anchoring end; 201, expansion block; 202, fixing ring; 203, extrusion block; 3, free end; 301, tray; 302, nut; 303, limiting snap ring; 4, drum-shaped shear-resistant structure; 401, boss; 402, tooth groove. DETAILED DESCRIPTION

[0022] The following will be combined with the Figures 1-5 The application is further described in detail.

[0023] The application embodiment discloses a small coal pillar roadway shear-resistant anchor rod supporting structure. Figures 1-5 A small coal pillar roadway shear-resistant anchor rod supporting structure, comprising an anchor rod body 1;

[0024] The middle section outer wall of the anchor rod body 1 is provided with a drum-shaped shear-resistant structure 4, the drum-shaped shear-resistant structure 4 comprises a boss 401 fixedly connected to the middle section outer wall of the anchor rod body 1, the outer wall of the boss 401 is provided with a plurality of tooth grooves 402, the plurality of tooth grooves 402 are evenly distributed in an equidistant circumferential array, and the cross-sectional shape of the tooth groove 402 is isosceles trapezoidal, and the slot width is greater than the slot bottom width;

[0025] One end of the anchor rod body 1 is provided with an anchoring end 2, and the other end is provided with a free end 3;

[0026] The outer wall of the free end 3 is provided with a thread, the outer wall of the free end 3 is sleeved with a tray 301, the tray 301 is a circular plate structure, the area of the plate surface is greater than the cross-sectional area of the anchor rod body 1, and the tray 301 is provided with a through hole matched with the anchor rod body 1, and the edge of the through hole is provided with a chamfer; the outer wall of the free end 3 is connected with a nut 302 through a thread, the nut 302 is located above the tray 301, and the anchor rod body 1 is sleeved with a limiting snap ring 303 close to the outer wall of the free end 3.

[0027] The limiting snap ring 303 is a 10mm-thick Q345B steel ring and is in interference fit with the anchor rod body 1. The limiting snap ring 303 is embedded in a 20mm-deep groove on the surrounding rock surface and is located between the tray 301 and the surrounding rock. The inner wall and the outer wall of the limiting snap ring 303 are subjected to rust-proof treatment, and the inner wall is provided with anti-skid lines.

[0028] The boss 401 has a diameter of 26mm and a length of half of the anchor rod body 1. The outer wall of the plurality of tooth grooves 402 is processed with a plurality of tooth grooves. The depth and the pitch of the tooth grooves are optimized and designed to strengthen the mechanical engagement with the anchoring agent. The boss 401 is integrally formed with the anchor rod body 1, and the material of the boss 401 is the same as that of the anchor rod body 1, which is high-strength alloy steel material, and the yield strength is not less than 600MPa.

[0029] The anchoring end 2 includes an expansion block 201, a fixing ring 202 and an extrusion block 203. The extrusion block 203 is fixedly connected to one end of the anchor rod body 1 away from the free end 3. The extrusion block 203 is tapered, and the taper is 1:5-1:3. The fixing ring 202 is sleeved on the outside of the anchor rod body 1. A plurality of extrusion blocks 203 are fixedly connected to the inner wall of the fixing ring 202. A plurality of expansion blocks 201 are in abutment with the outer wall of the extrusion block 203 away from the fixing ring 202. The expansion block 201 is made of expandable metal material, and its volume can increase by 10%-20% when subjected to extrusion.

[0030] The anchoring end 2 is inclined by 15-20° to the vertical direction of the roadway side, and forms an angle of 30-45° with the horizontal stress direction. After the anchoring end 2 is installed at an angle, the friction between the expansion block 201 and the borehole wall can provide an anchoring force of not less than 100kN.

[0031] The drum-shaped shear-resistant structure 4 can improve the shear resistance of the anchor rod anchoring section. The limiting snap ring 303 can effectively limit the transverse displacement of the anchor rod body 1. The inclined arrangement of the anchoring end 2 can greatly convert the shear force acting on the anchor rod into axial tension and disperse the remaining transverse pressure, forming a cooperative shear mode.

[0032] The plate surface of the tray 301 is provided with anti-skid protrusions (not shown in the figure). The anti-skid protrusions are hemispherical and uniformly distributed on the plate surface of the tray 301. The height of the anti-skid protrusions is 2mm-3mm to increase the friction between the tray 301 and the surrounding rock surface.

[0033] The fitting accuracy of the internal thread of the nut 302 and the external thread of the free end 3 of the anchor rod body 1 is 6g / 6H. The width of the hexagonal head opposite sides of the nut 302 is 24mm-27mm to facilitate tightening operation using a wrench.

[0034] The length of the anchor rod body 1 is 2000mm-2500mm. The surface of the anchor rod body 1 is subjected to corrosion protection treatment to improve its service life in the underground environment.

[0035] The implementation principle of the small coal pillar roadway anti-shearing anchor support structure according to an embodiment of the application is as follows: in the construction area of the small coal pillar roadway, according to the specific geological conditions of the roadway and the size of the small coal pillar and other factors, parameters such as the arrangement interval, length and inclination angle of the anchor rod are determined in combination with the design requirements, the required materials are prepared, including the anchor rod body 1 (made of high-strength alloy steel), the limiting snap ring 303 of Q345B steel material, the tray 301, the nut 302, the resin anchoring agent for anchoring and the like, and corresponding construction equipment such as an anchor rod drilling machine, a torque wrench and the like, and the equipment is debugged and checked to ensure that the performance is good;

[0036] The anchor rod body 1 is processed, a boss 401 with a diameter of 26 mm and a length of half of the anchor rod body 1 is fixedly connected to the outer wall of the middle section by forging or mechanical processing, and a plurality of tooth grooves 402 are processed on the outer wall of the boss 401, the depth and interval of which are optimized and designed to strengthen the mechanical bite with the anchoring agent, and the plurality of tooth grooves 402 are evenly distributed in an equidistant circumferential array to form a drum-shaped anti-shearing structure 4.

[0037] The limiting snap ring 303 is made of Q345B steel with a thickness of 10 mm and is processed into a steel ring with an inner diameter of 22 mm (with an interference fit with the anchor rod body 1) and an outer diameter of 80 mm;

[0038] The components of the anchoring end 2 are prepared, the extrusion block 203 is fixedly connected to one end of the anchor rod body 1 away from the free end 3, so that the extrusion block 203 is conical, the fixing ring 202 is sleeved on the outside of the anchor rod body 1, and a plurality of extrusion blocks 203 are fixedly connected to the inner wall of the fixing ring 202, and a plurality of expansion blocks 201 are prepared, one end of each expansion block 201 away from the fixing ring 202 can abut against the outer wall of the extrusion block 203;

[0039] The anchor rod drilling machine is used to drill a hole at the designed position and inclination angle on the roadway side, for the side corner anchor rod, the anchor rod is inclined to the vertical direction of the roadway side by 15-20° (forms a 30-45° angle with the horizontal stress direction), the drilling diameter should be greater than the diameter of the boss 401 by 6 mm to ensure that the anchor rod can be smoothly inserted, the drilling depth is determined according to the anchoring length requirement of the anchor rod, and generally the anchoring end 2 of the anchor rod can be ensured to be deep into the stable rock mass, after the drilling is completed, the rock powder and debris in the drilling hole are cleaned by using high-pressure air or other cleaning tools to ensure the cleanliness of the drilling hole wall;

[0040] Then the prepared anchor rod body 1 is inserted into the drilling hole, the anchoring end 2 is first rotated and pushed at a certain speed by the anchor rod drilling machine, so that the expansion structure of the anchoring end 2 is in extrusion contact with the drilling hole wall in the rotating process to generate mechanical expansion bite, after the anchoring end 2 is deep into the predetermined position of the drilling hole and forms a preliminary expansion fixation, the pushing is paused and the rotation is maintained for a proper time to ensure that the expansion structure is tightly engaged with the hole wall;

[0041] Further, the resin anchoring agent is injected into the borehole through the grouting equipment, and the rotation speed is simultaneously increased during the injection process, and the rotation is continuously maintained for a proper time to ensure that the anchoring agent is fully filled into the gap between the anchor rod body 1 and the borehole wall, the tooth groove 402 of the drum-shaped shear-resistant structure 4, and the expansion structure occlusion gap. Through the dual action of the instantaneous mechanical fixation and chemical bonding of the anchoring agent, the interfacial bonding force and shear resistance of the anchor rod and the rock mass are greatly improved.

[0042] At the position of the anchor rod body 1 close to the free end 3, a groove with a depth of 20 mm is pre-excavated on the surrounding rock surface, the limiting snap ring 303 is sleeved on the anchor rod body 1 and embedded in the groove, and the limiting snap ring 303 is located between the tray 301 and the surrounding rock. The tray 301 is sleeved on the free end 3 of the anchor rod body 1, and the central hole of the tray 301 is aligned with the free end 3 of the anchor rod body 1.

[0043] The nut 302 is threadedly connected to the free end 3 of the anchor rod body 1 using a torque wrench, and the nut 302 is tightened according to the designed torque, so that the tray 301 is tightly pressed against the surrounding rock surface, and the limiting snap ring 303 is in close contact with the surrounding rock through the pre-tightening force.

[0044] When the small coal pillar roadway is subjected to high stress, especially the influence of horizontal stress, the anchoring end 2 of the anchor rod is tightly combined with the borehole wall under the action of the expansion block 201 extruded by the extrusion block 203, providing reliable anchoring force. The boss 401 and the tooth groove 402 of the drum-shaped shear-resistant structure 4 increase the contact area with the resin anchoring agent and the hole wall, and enhance the shear resistance of the anchoring section, effectively resisting shear force and preventing shear failure of the anchor rod at the anchoring section. The limiting snap ring 303 limits the transverse displacement of the anchor rod body 1 by interference fit with the anchor rod body 1 and embedding in the groove on the surrounding rock surface, so that the transverse displacement does not exceed the designed allowable range, avoiding the attenuation of the pre-tightening force caused by excessive transverse displacement. At the same time, the inclined arrangement of the floor corner anchor rod decomposes the shear force generated by the horizontal stress into axial tension and transverse pressure, optimizes the stress transmission path, and enables the anchor rod to better withstand stress, thereby achieving effective support of the surrounding rock of the small coal pillar roadway, improving the stability and safety of the roadway.

[0045] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application. Therefore, any equivalent changes made on the basis of the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A shear-resistant bolting structure for a gob-side entry, comprising a bolt body (1), characterized in that: The outer wall of the middle section of the anchor rod body (1) is provided with a drum-shaped shear structure (4), the drum-shaped shear structure (4) comprises a boss (401) fixedly connected to the outer wall of the middle section of the anchor rod body (1), and the outer wall of the boss (401) is provided with a plurality of tooth grooves (402) which are uniformly distributed in an equidistant circumferential array. The anchor rod body (1) is provided with an anchoring end (2) at one end and a free end (3) at the other end, the outer wall of the free end (3) is provided with threads, the outer wall of the free end (3) is sleeved with a tray (301), the outer wall of the free end (3) is threadedly connected with a nut (302), the nut (302) is located above the tray (301), and the outer wall of the anchor rod body (1) near the free end (3) is sleeved with a limiting snap ring (303).

2. A shear-resistant bolt support structure for a gateroad with a small coal pillar according to claim 1, characterized in that: The limiting snap ring (303) is a 10mm-thick Q345B steel ring and is in interference fit with the anchor rod body (1), the limiting snap ring (303) is embedded in a 20mm-deep groove in the surface of the surrounding rock and is located between the tray (301) and the surrounding rock.

3. A shear-resistant bolt support structure for a gateroad with a small coal pillar according to claim 2, characterized in that: The diameter of the boss (401) is half the length of the anchor rod body (1), the plurality of tooth grooves (402) are distributed according to certain rules, and the depth and spacing are adapted to the characteristics of the anchoring agent to enhance the biting effect.

4. A shear-resistant bolting arrangement for a gateroad with a small coal pillar according to claim 1, characterized in that: The anchoring end (2) comprises expansion blocks (201), a fixing ring (202) and extrusion blocks (203), the extrusion blocks (203) are fixedly connected to one end of the anchor rod body (1) away from the free end (3), the extrusion blocks (203) are conical, the fixing ring (202) is sleeved on the outside of the anchor rod body (1), the plurality of extrusion blocks (203) are fixedly connected to the inner wall of the fixing ring (202), and the plurality of expansion blocks (201) are in abutment with the outer wall of the extrusion blocks (203) away from the fixing ring (202).

5. A shear-resistant bolt support structure for a gateroad with a small coal pillar according to claim 4, characterized in that: The anchoring end (2) is inclined by 15-20° to the vertical direction of the roadway side and forms an angle of 30-45° with the horizontal stress direction.

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