A method for vertical anchoring and withdrawing of a support frame under the condition of broken roof

Abstract

This invention belongs to the field of hydraulic support withdrawal technology in fully mechanized coal mining faces, and discloses a method for vertical anchoring and withdrawal of supports under fractured roof conditions: A transition support at the end of the working face is selected as the support to be withdrawn; after lowering the support to its minimum height, it is pulled to a position in front of the working face in the direction of advancement; the support is rotated so that the top beam and the support to be withdrawn form an angle of 80°~100°, and the support is tightened to ensure the top beam is firmly connected to the roof, achieving vertical anchoring; a pulley suspension seat is fixed at the base of the support, but the pulley suspension seat is not connected to the roof strata; the wire rope of the withdrawal winch is passed through the pulley suspension seat and connected to the support to be withdrawn, and the withdrawal winch is started to pull it out; after withdrawing 2~3 supports, a grid of timber is constructed in the withdrawal area; until all supports to be withdrawn except the support to be withdrawn are withdrawn, the support to be withdrawn is finally withdrawn; this invention eliminates the dependence on roof anchor bolts and is applicable to various fully mechanized mining faces with fractured roofs and failed anchor bolts.

Description

Technical Field

[0001] This invention belongs to the technical field of hydraulic support retraction in fully mechanized coal mining faces, specifically relating to a method for vertical anchoring and retraction of hydraulic supports under conditions of fractured roof. Background Technology

[0002] After the longwall mining face is completed, the hydraulic supports of the working face need to be withdrawn to the roadway and transported out. Currently, the most common method is the winch-guided wheel traction withdrawal method: anchor bolts are installed on the roof of the withdrawal channel, guide wheels are suspended from the anchor bolts, the winch wire rope is looped around the guide wheel and connected to the support to be withdrawn, and the winch is started to pull the support out. This method works effectively when the roof is intact and the rock strata are firm, but its reliability depends entirely on the pull-out force of the roof anchor bolts.

[0003] When the working face roof is fractured and the ground pressure is high (such as weak and fractured roofs like sandy mudstone or shale), the roof rock structure itself is damaged, and the anchor pull-out force drops sharply, far below the safety standard. At this time, if the winch applies traction, the guide wheel is very likely to detach from the roof, causing the wire rope to spring out, the support to go out of control, and resulting in a major safety accident. Field practice shows that under these conditions, a maximum of only 6 supports can be withdrawn per shift, which is extremely inefficient and extremely risky.

[0004] Although the existing "single-frame shield method" introduces a shield support for roof support, its guide wheel is still suspended on the roof anchor bolt, which fails to solve the core problem of guide wheel detachment. Summary of the Invention

[0005] The purpose of this invention is to provide a method for vertical anchoring and retraction of hydraulic supports under conditions of fractured roof, enabling safe and efficient retraction of hydraulic supports without relying on roof anchors, even when the roof is fractured and the anchor pull-out force is severely insufficient or even zero. The present invention adopts the following technical solution: A method for vertical anchoring and retraction of scaffolding under conditions of fractured roof slab includes the following steps: Step 1: Select a transition support at the end of the working face as the support to be reserved; Step 2: After lowering the support to its lowest height, pull it to the front position on the side of the working face's advancing direction; Step 3: Rotate the support frame so that its top beam is at an angle of 80° to 100° to the direction of the support frame to be removed, and tighten the support frame so that its top beam is firmly connected to the top plate to achieve vertical anchoring. Step 4: Fix a pulley suspension seat on the base of the support frame. The pulley suspension seat is not connected to the top rock layer. Step 5: Pass the wire rope of the pulley winch through the pulley hanger and connect it to the support to be retracted. Start the pulley winch to pull out the support to be retracted. Step 6: After every 2 to 3 scaffolds are withdrawn, construct a "well" shaped wooden stack in the withdrawal area; Step 7: Repeat steps 4 to 6 until all stents to be withdrawn except for the remaining stents have been withdrawn, and finally withdraw the remaining stents.

[0006] The beneficial effects of this invention are as follows: This invention replaces the suspension carrier of the guide wheel from the fractured roof rock layer to the steel structure base of the support frame, so that the traction reaction force is borne by the high-strength steel structure, thereby completely eliminating the dependence on the pull-out force of the roof anchor bolts and eliminating the safety hazard of the guide wheel detachment; at the same time, by rotating the support frame to form an 80°~100° angle with the direction of the support frame to be withdrawn and raising it tightly to the top, its top beam actively supports the roof and the base provides anchoring points; together with the "well" shaped wooden stacks constructed after each withdrawal of 2~3 supports to form a joint support system, the support frame bears the dynamic traction load, and the wooden stacks bear the static roof pressure, effectively preventing the roof from collapsing instantly during the withdrawal process. Therefore, this invention can significantly improve the safety and efficiency of withdrawal operations under fractured roof conditions and reduce the consumption of support materials. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the planar arrangement of the present invention; In the diagram, 1. Support frame, 2. Support frame to be retracted, 3. Pulley hanger, 4. Removal winch, 5. Loading winch, 6. Transport winch, 7. "Well" shaped timber stack, 8. Guide pulley. Detailed Implementation

[0008] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0009] In one embodiment, a method for vertical anchoring and retraction of the support structure under conditions of a broken roof is provided, comprising the following steps: Step 1: Select a transition support at the end of the working face as the support 1.

[0010] For example, start with the first transition support at the head or tail of the machine face.

[0011] Step 2: After lowering the support bracket 1 to its lowest height, pull it to the front position on the side of the working face advancing direction.

[0012] Specifically, first, all the jacks of the support 1 are retrieved and lowered to the lowest level. The side guard plate is then retrieved and locked. Then, the retraction winch is used to pull it to the front of the adjacent intermediate support (i.e., one side of the working face advancing direction).

[0013] Step 3: Rotate the support 1 so that its top beam direction forms an angle of 80°~100° with the arrangement direction of the support 2 to be withdrawn, and tighten the support 1 so that its top beam is firmly connected to the top plate to achieve vertical anchoring.

[0014] Specifically, the support 1 is usually rotated 90° so that its top beam is perpendicular to the arrangement direction of other supports, and then the support is tightened with a top pressure of not less than 15MPa.

[0015] Step 4: Fix a pulley hanger 3 on the base of the support 1. The pulley hanger 3 is not connected to the top rock layer.

[0016] Specifically, the pulley hanger 3 is clamped onto the structural beam of the base using a U-shaped buckle.

[0017] Step 5: Pass the wire rope of the pulley winch 4 through the pulley hanger 3 and connect it to the support 2 to be retracted. Start the pulley winch 4 to pull out the support 2 to be retracted.

[0018] Specifically, the traction speed of the draw frame winch 4 is controlled at 0.3m / s to 0.5m / s.

[0019] Step 6: After every 2 to 3 units of the support frame 2 are withdrawn, construct the "well" shaped wooden stack 7 in the withdrawal area.

[0020] Specifically, the "well" shaped wooden stack 7 is made of round logs and forms a joint support with the reserved support frame 1.

[0021] Step 7: Repeat steps 4 to 6 until all supports 2 to be withdrawn except for support 1 have been withdrawn, and finally withdraw support 1.

[0022] In another embodiment, the included angle in step 3 is 90°. That is, the direction of the top beam of the support 1 is perpendicular to the arrangement direction of the support 2 to be withdrawn. Field tests have shown that a 90° perpendicular arrangement maximizes the coverage width of the top beam of the support 1 (approximately 2 to 3 times the width of the support), resulting in the best support effect. At the same time, the direction of the base toward the support 2 to be withdrawn is also the most reasonable, facilitating the guidance of the wire rope.

[0023] In another embodiment, the pulley suspension bracket 3 is connected to the structural beam supporting the base of the bracket 1 via at least two U-shaped clips. Specifically, the U-shaped clips are high-strength bolt-type clips of M24 or M30, with the opening facing upwards, embracing the base beam from below. Their threaded legs pass upwards through through holes in the base plate, and are then locked in place with nuts above the base plate, with a tightening torque of not less than 200 N·m. The two U-shaped clips are fixed to different positions on either side or on the same side of the base beam to ensure that the suspension bracket does not shift during traction.

[0024] In another embodiment, in step 6, the "well" shaped wooden stack 7 is formed by stacking round logs with a diameter of not less than 160mm into a well shape. The height of the "well" shaped wooden stack 7 is not less than 2.4m, and the distance between every two "well" shaped wooden stacks 7 is not greater than 5m. The intersection of the round logs is fixed with double nails.

[0025] In another embodiment, a condition determination step is included before step 1: the pull-out force of the top slab anchor bolts in the withdrawal area is measured. If the pass rate is less than 70%, the method is deemed appropriate. For example, 3 to 5 anchor bolts are randomly selected within a 10-meter range and tested using an anchor bolt pull-out gauge. If the average pull-out force is less than 70% of the design value, or if there is obvious pull-out or loosening, it indicates that the top slab is broken and the anchoring has failed, and the method of the present invention is activated.

[0026] In another embodiment, the number of support frames 1 is 1 to 3. When the roof is fractured and the pressure is high, 2 to 3 frames are selected and arranged at intervals of 5m to 10m along the dip of the working face. For example, if the roof of the working face is extremely fractured carbonaceous mudstone and the ground pressure is severe, one transition support frame can be selected at the head, middle and tail of the machine as support frame 1, spaced at intervals of 8m along the dip, forming multiple points of vertical anchorage to jointly bear the traction reaction force and the roof pressure.

[0027] In another embodiment, a large tilt angle adaptation step is also included: when the tilt angle of the working surface is greater than 25°, the rotation direction of the retaining bracket 1 is directed towards the downward tilt of the working surface, and an anti-slip support rod is added to the side of the base of the retaining bracket 1 facing downward tilt.

[0028] Specifically, "along the downward slope" refers to the lower end of the inclined plane of the working face, i.e., the downhill direction. Pointing the top beam of the support 1 in this direction will shift the center of gravity of the support downward, utilizing its own weight to generate an anti-slip force.

[0029] The anti-slip support rod is a section of adjustable-length steel pipe (60mm~80mm in diameter) or I-beam. One end is fixed to the ear plate on the side of the base through a hinge seat, and the other end is processed into a sharp corner or has an anti-slip pad, which is pressed against the bottom plate or coal wall. The angle between the support rod and the bottom plate is usually 30°~45°. After tightening the adjusting nut, a rigid support is formed to prevent the support from sliding down.

[0030] In another embodiment, after step 5, a loading step is also included: the bracket to be retracted 2 is connected to the loading winch 5, the loading winch 5 is started to pull it to the loading platform and load it onto the vehicle and fix it, and then the transport winch 6 transports it out along the track.

[0031] Specifically: After the pull-out winch 4 has dragged the support away from its original position by about 2m, remove the wire rope of the pull-out winch 4.

[0032] Anchor bolts are installed in the stable rock strata of the roof or sidewalls near the loading area. The guide pulley 8 is suspended on the anchor bolts, and the wire rope of the loading winch 5 is passed through the guide pulley 8 and connected to the support base.

[0033] Start the loading winch 5 to pull the support onto the flatbed truck along the loading platform; use a single hydraulic prop or special jack to adjust the position of the support on the flatbed truck so that its center of gravity is centered, and then use M30 special bolts and anti-loosening clamps to firmly fix the support to the flatbed truck.

[0034] Start the transport winch 6 to transport the flatbed car with the support frame along the track to the machine head of the working face or the external loading point.

[0035] In another embodiment, a track recovery step is also included: one to two sections of track are removed in advance as the support retracts. That is, as the working face support retracts frame by frame from the inside out, the track is also removed section by section from the inside out accordingly, keeping the transportation line synchronized with the retraction progress and avoiding excessive track length from affecting loading and transportation.

[0036] In another embodiment, the method also includes a two-way pre-support recovery step: three round logs are supported in each row from the inside out, with a row spacing of 1m. After one row is supported, the individual support columns and steel beams of that row are removed. Recovery is stopped when the top plate is broken or the steel beam is bent by more than 300mm.

[0037] In practice, starting from the innermost end of the roadway, first install three round logs (with a diameter of not less than 180mm) at the new location, with the tops of the logs secured by wooden wedges. After confirming the reliability of the new support, remove the existing single hydraulic props and I-beams at that location. Then move outwards by 1m and repeat the above process. If the roof is visibly broken or the steel beams are bent and deformed by more than 300mm, it indicates that the pressure in that area is too high, and the area will not be recovered; it will be retained as permanent support.

[0038] The effects of the present invention will be further illustrated below with reference to three embodiments.

[0039] Example 1: Taking the 23306 working face of a certain mine as an example, the roof is sandy mudstone, and the anchor pull-out force qualification rate is 45%. Three winches are configured on site: The No. 1 winch (JH-20T return column winch) serves as the fourth winch for the frame removal, with a rated traction force of 200kN. The No. 2 winch (JH-20T return winch) serves as the loading winch 5, with a rated traction force of 200kN; The No. 3 winch (JD-25KW dispatch winch) serves as transport winch 6, with a rated traction force of 250kN~390kN.

[0040] The implementation steps are as follows: Select the first transition support at the machine head as support 1, and tighten the second intermediate support to the top (pressure 16MPa).

[0041] Set up support 1, lower the frame, retract the side guard plate, and use a JH-20T winch to pull it to the front of the second frame (i.e., the front position on the side of the working face advance direction), rotate it 90° vertically, and lift it tightly to the top (pressure 15MPa) to complete the vertical anchoring posture.

[0042] Install pulley suspension seat 3 (fixed by U-shaped buckle, torque 220 N·m) on the base of the support 1, pass the No. 1 winch wire rope through the pulley, and connect it to the base of the second support.

[0043] Start the No. 1 winch (frame removal winch 4) and drag the second support frame away from its original position by about 2m at a speed of 0.3m / s.

[0044] Connect the second support frame to the wire rope of the second winch (loading winch 5). The guide pulley 8 of the loading winch 5 is fixed to the anchor bolt on the top plate of the loading area. Start the second winch to pull it to the loading platform and pull it onto the flatbed truck. Adjust its posture with a single support and then fix it.

[0045] For every two supports removed, construct a 2.4m×2.4m "well" shaped wooden stack 7 (round logs with a diameter of 18cm, fixed with nails) on both the coal face side and the side where the original supports were located.

[0046] Start the No. 3 winch (transport winch 6) to transport the flatbed car and support along the track to the loading point at the machine head.

[0047] The 3rd to 119th frames were withdrawn in sequence, and the timber stacking construction was repeated after every 2 to 3 frames were withdrawn.

[0048] Finally, the first support frame (the first frame) will be dismantled and removed in the order of top beam, tail beam, column, and base.

[0049] Example 2: A mine working face has a dip angle of 28° and a broken roof. This embodiment makes the following adaptive adjustments for steep dip conditions: In step 3, the rotation direction of the support 1 is directed towards the downward slope of the working surface (i.e., the lower end of the terrain), so that the top beam of the support 1 is arranged in the inclined direction. This arrangement utilizes the self-weight of the support to generate a downward component force, increasing the friction between the support and the base plate, and preventing the support from sliding down the slope under the action of gravity.

[0050] Meanwhile, an anti-slip brace is added to the side of the base of the support 1 facing downwards. The anti-slip brace is a section of steel pipe or I-beam with an adjustable length, the length of which is determined according to the distance between the base of the support 1 and the bottom plate or coal wall. One end of the anti-slip brace is connected to the side of the base of the support 1 through a hinged seat, and the other end rests on the bottom plate or coal wall at an angle of approximately 30° to 45° with the bottom plate, forming a physical stop to further prevent the support 1 from sliding in the inclined direction.

[0051] The remaining steps are the same as in Example 1. After the above adjustments, this method can also safely and efficiently complete the support retraction on a steeply inclined working surface.

[0052] Example 3: The roof of a certain mine working face consisted of extremely fractured carbonaceous mudstone, with a maximum anchor pull-out force of only 0.5 tons. Using this method, after vertical anchoring of support 1, the first intermediate support was successfully pulled out by the winch 4. During the process, the pulley suspension seat 3 showed no displacement, and no large-scale roof collapse occurred. This demonstrates the reliability of this method even under conditions of complete anchor failure.

[0053] The method of the present invention has the following effects: 1. The improved solution is simple, convenient, and low-cost, reducing the labor intensity of employees.

[0054] 2. High efficiency: The maximum number of supports that can be withdrawn per shift has been reduced from 6 to 14, increasing the working efficiency by 2.3 times. The time for withdrawing supports has been reduced from 21 days to 12 days.

[0055] 3. Cost savings: The materials used for the original 23308 mining face support are three times that used with the method of this invention, saving approximately 200,000 yuan in costs.

[0056] 4. High safety factor: The construction of a "well" shaped wooden stack under the top beam of the support reduces the probability of injury to workers due to roof breakage and prevents the support from being buried by roof gangue.

[0057] 5. The construction process is simple, reducing the number of times workers need to hang anchor rods on the guide wheels and strengthening the support of the side roof slab of the pedestrian passage.

Claims

1. A method for vertical anchoring and retraction of scaffolding under conditions of broken roof slab, characterized in that, Includes the following steps: Step 1: Select a transition support at the end of the working face as the support to be reserved; Step 2: After lowering the support frame to its lowest height, pull it to the front position on the working face advancing direction side; Step 3: Rotate the support frame so that its top beam direction forms an angle of 80°~100° with the arrangement direction of the support to be withdrawn, and tighten the support frame so that its top beam is firmly connected to the top plate to achieve vertical anchoring; Step 4: Fix a pulley suspension seat on the base of the reserved support, the pulley suspension seat is not connected to the top rock layer; Step 5: Pass the wire rope of the draw frame winch through the pulley hanger and connect it to the support to be retracted. Start the draw frame winch to pull out the support to be retracted. Step 6: After every 2 to 3 scaffolds are withdrawn, construct a "well" shaped timber stack in the withdrawal area; Step 7: Repeat steps 4 to 6 until all supports to be withdrawn except for the existing support have been withdrawn, and finally withdraw the existing support.

2. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, The included angle in step 3 is 90°.

3. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, The pulley hanger is connected to the structural beam with the support base via at least two U-shaped buckles.

4. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, In step 6, the "well" shaped wooden stack is formed by stacking round logs with a diameter of not less than 160mm into a well shape. The height of the "well" shaped wooden stack is not less than 2.4m, and the distance between any two "well" shaped wooden stacks is not greater than 5m. The intersections of the round logs are fixed with double nails.

5. The method for vertical anchoring and retraction of the support frame under the condition of a broken roof as described in claim 1, characterized in that, Before step 1, there is also a condition determination step: measure the pull-out force of the top plate anchor bolts in the withdrawal area. If the pass rate is less than 70%, then this method is adopted.

6. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, The number of supports is 1 to 3. When the top plate is broken and the pressure is high, 2 to 3 supports are selected and arranged at intervals of 5m to 10m along the working face.

7. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, It also includes a large tilt angle adaptation step: when the tilt angle of the working surface is greater than 25°, the rotation direction of the retaining bracket is directed towards the downward tilt of the working surface, and an anti-slip support rod is added to the side of the retaining bracket base facing downward tilt.

8. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, After step 5, a loading step is also included: connecting the support to be retracted to the loading winch, starting the loading winch to pull the support to be retracted to the loading platform and load and fix it on the vehicle.

9. The method for vertical anchoring and retraction of the support frame under broken roof conditions according to claim 1, characterized in that, It also includes a track recovery step: removing 1 to 2 sections of track in advance, following the retraction direction of the support to be retracted.

10. A method for vertical anchoring and retraction of the support frame under fractured roof conditions according to claim 1, characterized in that, It also includes the two-way pre-support recovery steps: three round logs are supported in each row from the inside out, with a row spacing of 1m. After one row is supported, the individual support columns and steel beams of that row are removed; when the roof is broken or the steel beam is bent by more than 300mm, the recovery is stopped.

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