Secondary yielding anchor rod and gob-side entry retaining secondary yielding anchoring support method

Abstract

The invention belongs to the field of coal mine roadway anchor rod supporting, and particularly relates to a secondary yielding anchor rod and a gob-side entry retaining secondary yielding anchoring supporting method. In the gob-side entry retaining construction process, a roof can generate two times of large disturbance, a secondary yielding anchor rod is configured on the basis of the discovery, a first yielding structure is arranged in the middle of the anchor rod of the secondary yielding anchor rod, the situation that the roof is suspended and moves downwards due to working face stoping can be adapted, collapse of the gob-side entry retaining roof caused by excessive sinking of the roof is avoided, and the working efficiency is improved. And the top plate sinks to a certain degree to prevent the anchor rod from being snapped. The secondary yielding anchor rod is further provided with a controllable second yielding structure at an orifice, and the second yielding structure works when a cementing material for constructing a retaining wall of the gob-side entry is solidified and contracted and is not in contact with the roof, so that the secondary yielding anchor rod has a yielding function again, the anchor rod is prevented from being snapped, and the service life of the anchor rod is prolonged. And the problems that the construction height of the retaining wall of the gob-side entry retaining is small and the sinking amount of a top plate is large due to continuous yielding of a single yielding structure can be solved.

Description

Technical Field

[0001] This invention belongs to the field of coal mine roadway anchor support, specifically involving secondary pressure relief anchor bolts and secondary pressure relief anchor support methods for roadway retention along the goaf. Background Technology

[0002] In mining roadways, bolt support is generally used. Bolt support has advantages such as good support effect, fast support speed, high degree of mechanization, and low cost. Bolt support can effectively control the deformation of the surrounding rock in the roadway, but it cannot completely prevent deformation. Sometimes it can only slow down the deformation. However, allowing the surrounding rock to undergo controllable deformation and letting the bolts adapt to this deformation, followed by further anchoring and reinforcement, is more beneficial for the support after the surrounding rock has deformed. Bolts with this function are called yielding bolts.

[0003] Gob-side retention is a common method of arranging mining roadways. It involves preserving the haulage roadway from the previous working face by constructing a gob-side retention wall, allowing it to continue serving the next working face as its return airway. This type of gob-side retention typically experiences two major disturbances. The first occurs after the working face is mined, when the coal seam supporting its roof on one side is excavated, causing that side of the roof to subside. Subsequently, a gob-side retention wall is constructed to replace the mined coal seam and support that side of the roof. However, because the cementing material of the gob-side retention wall shrinks after solidification, the wall may not connect to the roof after solidification, causing the roadway roof to subside again.

[0004] However, most existing pressure-relief anchor bolts are single-stage pressure-relief anchor bolts. When applied to the above-mentioned environment, the continuous operation of the pressure-relief structure after coal seam mining will result in a small height of the retaining wall along the goaf. After the cementing material of the retaining wall along the goaf solidifies, it will shrink, and the roof will be suspended again. If the anchor bolt continues to provide pressure, the total pressure relief will be large, resulting in poor roadway support. If the anchor bolt cannot continue to provide pressure, the anchor bolt will be subjected to large tensile stress for a long time under the suspended roof, which may cause the anchor bolt to break.

[0005] Therefore, how to adapt to the characteristics of secondary disturbances along the goaf and to reduce pressure in stages has become a difficult problem to be solved in this field. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a secondary pressure-relief anchor bolt, comprising a lower hollow rod body and an upper solid rod body; the upper end of the hollow rod body is fixedly connected to the bottom end of a first pressure-relief sleeve, the opening of the first pressure-relief sleeve faces upward, and a second grout stop plug is fixedly attached to the top of the first pressure-relief sleeve; a first pressure-relief block is fixedly connected to the lower end of the solid rod body, and the first pressure-relief block is disposed within the first pressure-relief sleeve; a second pressure-relief sleeve, a tray, and a first grout stop plug are sequentially arranged adjacently on the lower part of the hollow rod body, and grouting holes are radially arranged on the portion of the hollow rod body above the first grout stop plug; the second pressure-relief sleeve opens downward, and a second pressure-relief block is fixedly disposed on the hollow rod body; a radial limiting hole is also provided at the lower part of the second pressure-relief block on the hollow rod body, and when a limiting pin passes through the limiting hole, the movement of the second pressure-relief block relative to the second pressure-relief sleeve can be restricted.

[0007] Preferably, the inner wall of the first pressure relief sleeve is provided with an internal thread that inhibits the movement of the first pressure relief block under a set pressure.

[0008] Preferably, the diameter of the first pressure block is larger than the diameter of the solid rod, and the opening diameter of the first pressure sleeve is the same as the diameter of the solid rod.

[0009] Preferably, the solid rod body is slidably sealed to the first grout stop plug, and the portion of the solid rod body above the first grout stop plug has an outer spiral.

[0010] Preferably, the hollow rod body has an outer spiral on its outer periphery above the first stop plug.

[0011] Preferably, the inner wall of the second pressure relief sleeve is provided with an internal thread that inhibits the movement of the second pressure relief block under a set pressure.

[0012] Preferably, the opening of the second pressure relief sleeve is consistent with the inner diameter of the upper cavity, a high-strength spring is coaxially sleeved inside the second pressure relief sleeve, and the second pressure relief block is located below the high-strength spring.

[0013] Based on the secondary pressure relief anchor bolts described above, this invention also proposes a method for secondary pressure relief anchoring support along the goaf, comprising the following steps:

[0014] S1: Use secondary pressure relief anchor bolts to support the transport tunnel; drill a hole to the basic roof, put resin cartridges into the top of the hole, install the secondary pressure relief anchor bolts, and make the first pressure relief sleeve located in the immediate roof; then install the orifice device.

[0015] S2: The working face is mined back, and the transport roadway is retained to form a roadway along the gob. The secondary pressure relief anchor is subjected to tensile force, and the first pressure relief block slips relative to the first pressure relief sleeve.

[0016] S3: When constructing a retaining wall for the goaf along the side of the goaf, after the cementing material of the retaining wall has solidified, the retaining wall will not be connected to the roof. When the limiting pin is removed, the second relief block will move relative to the second relief sleeve, causing the direct roof to slowly move down to the solidified retaining wall along the goaf.

[0017] Preferably, in step S1, the orifice device includes a tray, a second pressure relief sleeve, a second pressure relief block, a high-strength spring, and a limiting pin.

[0018] Preferably, step S3 further includes grouting the borehole through the grouting hole using a hollow rod.

[0019] Preferably, step S3 further includes grouting reinforcement of the delamination between the basic top and the immediate top.

[0020] The key technical means and beneficial effects of this invention are as follows: During the construction of the gob-side retaining wall, the roof will experience two significant disturbances. Based on this discovery, this invention configures a secondary pressure-relief anchor bolt. The secondary pressure-relief anchor bolt has a first pressure-relief structure in the middle of the bolt, which can adapt to the situation where the roof is suspended and moves downwards due to the working face mining. This avoids excessive roof subsidence that could cause the roof of the gob-side retaining wall to collapse, while also allowing the roof to subside to a certain extent to prevent the anchor bolt from breaking. The secondary pressure-relief anchor bolt also has a controllable second pressure-relief structure at the orifice. This second pressure-relief structure works when the cementing material of the gob-side retaining wall solidifies and shrinks, preventing it from contacting the roof. This allows the secondary pressure-relief anchor bolt to regain its pressure-relief function, preventing the anchor bolt from breaking. It also solves the problem of small construction height and large roof subsidence in the gob-side retaining wall caused by continuous pressure relief from a single pressure-relief structure. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the working surface layout of the present invention;

[0022] Figure 2 This is a schematic diagram of the plan view of the present invention for retaining the tunnel along the goaf;

[0023] Figure 3 This is a schematic diagram of the first transport tunnel before the first working face is mined in this invention.

[0024] Figure 4 This is a schematic cross-sectional view of the transition zone after the first working face has been mined according to the present invention.

[0025] Figure 5 This is a schematic diagram of the cross-section of the roadway left along the goaf after the first working face is mined in this invention;

[0026] Figure 6 This is a schematic diagram of the secondary pressure relief anchor bolt structure of the present invention;

[0027] Figure 7This is a schematic diagram of the construction of the secondary pressure relief anchor bolt of the present invention in the first transport tunnel;

[0028] Figure 8 This is a schematic diagram of the secondary pressure relief anchor bolt of the present invention at the transition zone position;

[0029] Figure 9 This is a schematic diagram of the construction of the secondary pressure relief anchor bolt of the present invention in the goaf-retaining tunnel;

[0030] In the diagram: 01-First working face; 02-Second working face; 03-First return airway; 04-First transport airway; 05-Second transport airway; 06-Second return airway / goaf retaining wall; 07-Goaf retaining wall; 08-Goaf; 09-Transition zone; 11-Solid coal; 12-Basic roof; 13-Issued roof; 14-Separation layer;

[0031] 21-Hollow rod body; 22-Tray; 23-First grout stop plug; 24-Grouting hole; 25-Outer spiral; 26-First pressure relief sleeve; 27-Solid rod body; 28-First pressure relief block; 29-Second grout stop plug; 31-Second pressure relief sleeve; 32-Second pressure relief block; 33-High-strength spring; 34-Limiting pin; 41-Anchoring cartridge; 42-Grouting body; 43-Tunnel wall. Detailed Implementation

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] Example 1

[0034] like Figure 6As shown, this invention proposes a secondary pressure-relief anchor bolt, comprising a lower hollow rod body 21 and an upper solid rod body 27. The upper end of the hollow rod body 21 is fixedly connected to the bottom end of a first pressure-relief sleeve 26, the opening of the first pressure-relief sleeve 26 facing upwards, and a second grout stop plug 29 fixed to the top end of the first pressure-relief sleeve 26. The lower end of the solid rod body 27 is fixedly connected to a first pressure-relief block 28, which is disposed in the first pressure-relief sleeve 26. The inner wall of the first pressure-relief sleeve 26 is provided with an internal thread (not shown in the figure) to suppress the movement of the first pressure-relief block 28 under a set pressure. The diameter of the first pressure-relief block 28 is larger than the diameter of the solid rod body 27, and the opening diameter of the first pressure-relief sleeve 26 is the same as the diameter of the solid rod body 27. The solid rod body 27 is slidably sealed to the first grout stop plug 29, and the outer periphery of the portion of the solid rod body 27 above the first grout stop plug 29 is provided with an outer... The hollow rod body 21 has a spiral 25. A second pressure-relieving sleeve 31, a tray 22, and a first grout stop plug 23 are sequentially arranged adjacently at the lower part of the hollow rod body 21. An outer spiral 25 is provided on the outer periphery of the portion of the hollow rod body 21 above the first grout stop plug 23, and a grouting hole 24 is provided radially. The second pressure-relieving sleeve 31 has an opening facing downwards, and the opening is consistent with the inner diameter of the upper cavity. A high-strength spring 33 is coaxially sleeved inside the second pressure-relieving sleeve 31. A second pressure-relieving block 32 is fixedly provided on the hollow rod body 21. The inner wall of the second pressure-relieving sleeve 31 is provided with an internal thread (not shown in the figure) that inhibits the movement of the second pressure-relieving block 32 under a set pressure. The second pressure-relieving block 32 is located below the high-strength spring. A radial limiting hole is also provided at the lower part of the second pressure-relieving block 32 on the hollow rod body 21. When a limiting pin 34 passes through the limiting hole, the movement of the second pressure-relieving block 32 relative to the second pressure-relieving sleeve can be restricted.

[0035] Example 2

[0036] like Figures 1-9 As shown, this invention also proposes a method for secondary pressure relief anchoring support along the goaf, based on secondary pressure relief anchor bolts, comprising the following steps:

[0037] S1: As Figure 1 , Figure 3 , Figure 6-7As shown, a first working face 01 is arranged, which includes a first return air level 03 and a first transport level 04. The first transport level 04 is supported by a secondary pressure relief anchor. A construction borehole is drilled into the basic roof 12. A resin cartridge 41 is placed into the top of the borehole, and a secondary pressure relief anchor is installed, so that the first pressure relief sleeve 26 is located below the basic roof 12 and inside the direct roof 13. The anchoring cartridge 41 is stirred and mixed evenly using the outer spiral 25 on the solid rod body 27. The secondary pressure relief anchor is fixed in the borehole using the anchoring cartridge 41. Then, a borehole device is installed, including a tray 22, a second pressure relief sleeve 31, a second pressure relief block 32, a high-strength spring 33, and a limiting pin 34. The limiting pin 34 can inhibit the movement of the second pressure relief block 32.

[0038] S2: As Figure 2 , Figure 4 and Figure 8 As shown, the first working face 01 is being mined. The coal body supporting the roof of the first transport roadway 04 in the first working face 01 is mined, and the first transport roadway 04 is retained to form a goaf retainer 06. The goaf in the goaf retainer refers to the goaf area 08 formed after the first working face 01 is mined. The goaf retainer 06 is only supported by solid coal 11 on one side of the second working face 02. The roof of the unsupported side sinks, and the sinking of the direct roof 13 is greater than that of the basic roof 12, resulting in a delamination 14 between the two. Under this uneven settlement, the secondary relief anchor will be subjected to tensile force. The first relief block 28 slides relative to the first relief sleeve 26 to adapt to this uneven settlement and prevent the secondary relief anchor from being pulled apart. Of course, the secondary pressure relief anchor bolt does not allow the direct roof 13 to sink freely, but controls its sinking amount to avoid excessive sinking that could cause the direct roof 13 to collapse along the goaf. It also allows the direct roof 13 to sink to a certain extent to prevent the anchor bolt from breaking. That is, the pressure relief amount (maximum pressure relief amount) that can be generated between the first pressure relief sleeve 26 and the first pressure relief block 28 is much smaller than the sinking amount that the direct roof 13 can generate.

[0039] S3: As Figure 2 , Figure 5 and Figure 9As shown, under the anchoring action of the secondary pressure-relief anchor bolt, the construction of the gob-side retaining wall 07 near the goaf 08 in the gob-side retaining roadway 06 forms the second return airway 06. The second return airway 06 and the second transport roadway 05 are the horizontal roadways used during the mining of the second working face 02. The material for constructing the gob-side retaining wall 07 can be paste or high-water-content cementing materials. After the cementing material of the gob-side retaining wall 07 solidifies, the gob-side retaining wall 07 will shrink, its height will decrease, and the gob-side retaining wall 07 will experience a phenomenon of not connecting to the roof (a phenomenon of non-connection between the gob-side retaining wall 07 and the immediate roof 13). (Interlayer voids); due to the small size of these voids, it is difficult to replenish the cementing material. However, if the direct roof 13 is suspended for a long time, the anchor rod will be subjected to a large tensile force for a long time, which may cause the anchor rod to break. At this time, the limiting pin 34 is pulled out; the second relief block 28 will move relative to the second relief sleeve 31, causing the direct roof 13 to slowly move down to the solidified goaf retaining wall 07; then, the borehole is reinforced by grouting through the grouting hole 24 via the hollow rod 21. The injected grout can also reinforce the cracks in the rock strata around the borehole. Finally, the delamination 14 can be reinforced by grouting as needed.

[0040] This invention is not limited to the preferred embodiments described above. Anyone can derive other methods in various forms under the guidance of this invention. Any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A secondary pressure relief anchor bolt, characterized in that, The device includes a lower hollow rod and an upper solid rod. The upper end of the hollow rod is fixedly connected to the bottom end of a first pressure-relief sleeve, the opening of which faces upward, and a second grout stop plug is fixed to the top of the first pressure-relief sleeve. The lower end of the solid rod is fixedly connected to a first pressure-relief block, which is disposed within the first pressure-relief sleeve. The lower part of the hollow rod is sequentially and adjacently provided with a second pressure-relief sleeve, a tray, and a first grout stop plug. The portion of the hollow rod above the first grout stop plug has a grouting hole arranged radially. The opening of the second pressure-relief sleeve faces downward, and a second pressure-relief block is fixedly disposed on the hollow rod. The lower part of the second pressure-relief block on the hollow rod is also provided with a radial limiting hole. When a limiting pin passes through the limiting hole, the movement of the second pressure-relief block relative to the second pressure-relief sleeve can be restricted.

2. The secondary pressure relief anchor bolt according to claim 1, characterized in that, The inner wall of the first pressure relief sleeve is provided with an internal thread that inhibits the movement of the first pressure relief block under a set pressure.

3. The secondary relief anchor bolt according to claim 1 or 2, characterized in that, The diameter of the first pressure block is larger than the diameter of the solid rod, and the opening diameter of the first pressure sleeve is the same as the diameter of the solid rod.

4. The secondary pressure relief anchor bolt according to claim 1, characterized in that, The solid rod body is slidably sealed to the first grout stop plug, and the outer periphery of the portion of the solid rod body above the first grout stop plug is provided with an outer spiral.

5. The secondary pressure relief anchor bolt according to claim 1, characterized in that, The hollow rod body has an outer spiral on its outer periphery above the first stop plug.

6. The secondary relief anchor bolt according to claim 1, characterized in that, The inner wall of the second relief sleeve is provided with an internal thread that inhibits the movement of the second relief block under a set pressure.

7. The secondary relief anchor bolt according to claim 1 or 6, characterized in that, The opening of the second pressure relief sleeve is consistent with the inner diameter of the upper cavity. A high-strength spring is coaxially sleeved inside the second pressure relief sleeve, and the second pressure relief block is located below the high-strength spring.

8. A method for secondary pressure relief anchoring support along a goaf, employing the secondary pressure relief anchor bolt as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Use secondary pressure relief anchor bolts to support the transport tunnel; drill a hole to the basic roof, put resin cartridges into the top of the hole, install the secondary pressure relief anchor bolts, and make the first pressure relief sleeve located in the immediate roof; then install the orifice device. S2: The working face is mined back, and the transport roadway is retained to form a roadway along the gob. The secondary pressure relief anchor is subjected to tensile force, and the first pressure relief block slips relative to the first pressure relief sleeve. S3: When constructing a retaining wall for the goaf along the side of the goaf, after the cementing material of the retaining wall has solidified, the retaining wall will not be connected to the roof. When the limiting pin is removed, the second relief block will move relative to the second relief sleeve, causing the direct roof to slowly move down to the solidified retaining wall along the goaf.

9. The method for secondary pressure relief anchoring support along the goaf as described in claim 8, characterized in that, In step S1, the orifice device includes a tray, a second pressure relief sleeve, a second pressure relief block, a high-strength spring, and a limiting pin.

10. The method for secondary pressure relief anchoring support along the goaf as described in claim 8 or 9, characterized in that, Step S3 further includes grouting reinforcement of the borehole through the grouting hole using a hollow rod; and / or Step S3 also includes grouting reinforcement of the delamination between the basic top and the immediate top.

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