A surrounding rock reinforcing and repairing structure and method for a coal-dropping passage in a mine

Abstract

The present application relates to the technical field of underground coal mine support, in particular to a kind of underground coal chute surrounding rock reinforcement repair structure and method, the structure includes a plurality of arc prefabricated supporting blocks, and is assembled into ring along the circumference of underground coal chute, the inner arc surface of supporting block is attached to the inner wall of channel, and grouting gap is formed between the two, grouting gap is filled with grouting body, grouting body is respectively bonded and fixed with supporting block and surrounding rock, and forms integrated load-bearing structure.Steel bars are arranged in supporting block, end is provided with mortise and tenon, upper portion is provided with lifting ring, and impact-resistant wear-resistant layer is arranged on inner arc surface.Repair method is as follows: prefabricating supporting block on ground;cleaning coal chute;directional hoisting and mortise splicing from shaft mouth;from top to bottom pressure grouting from top.The personnel is located outside the channel during the whole construction process.The present application is safe and efficient in construction, and the supporting structure has high integrity, impact resistance and wear resistance, the cumulative displacement of surrounding rock is less than or equal to 20mm in 30d, the bearing capacity is increased by more than 60%, and it is suitable for rapid reinforcement and repair of underground coal chute, coal discharge opening and other coal chute.

Description

Technical Field

[0001] This invention relates to the field of underground coal mine support technology, specifically a structure and method for reinforcing and repairing the surrounding rock of underground coal chutes. Background Technology

[0002] Coal chutes and coal outlets are crucial facilities for underground coal transportation and transfer. Their surrounding rock is subjected to multiple forces over long periods, including the impact and friction of falling coal and mine pressure, making it highly susceptible to problems such as rock fragmentation, spalling, and even collapse. This not only severely restricts coal transportation efficiency but can also lead to safety accidents, threatening the lives of underground workers.

[0003] Currently, common reinforcement and repair methods for the surrounding rock of underground coal chutes and coal outlets mainly include shotcrete support, anchor bolt and cable support, and ordinary concrete pouring support. However, all of the above methods have significant shortcomings:

[0004] Shotcrete support has low strength and poor impact resistance, making it prone to cracking and detachment under long-term coal flow impact, and it cannot form a tight bond with the surrounding rock. Anchor bolt and cable support has limited reinforcement effect on fractured surrounding rock, and the anchoring force is difficult to guarantee; more importantly, the construction process requires personnel to enter the narrow coal chute, posing extremely high safety risks. Ordinary concrete pouring support has a long construction cycle and complex procedures, requiring formwork erection, pouring, and curing, which significantly impacts mine production; furthermore, the bond between cast-in-place concrete and the surrounding rock is often not tight, easily forming voids and failing to form an effective integrated load-bearing structure.

[0005] Therefore, there is an urgent need for a technology to reinforce and repair the surrounding rock of underground coal chute that is easy to construct, safe and efficient, has good adhesion to the surrounding rock, strong impact resistance, and does not affect the normal coal chute function, in order to overcome the shortcomings in current practical applications. Summary of the Invention

[0006] The purpose of this invention is to provide a structure and method for reinforcing and repairing the surrounding rock of underground coal chutes. By adopting a complete set of technical solutions, namely "prefabricated arc-shaped blocks on the ground, directional assembly at the wellhead, and top pressure grouting", an integrated bearing structure of support block-grouting body-surrounding rock is formed, which realizes rapid and stable repair of the surrounding rock and ensures the smooth flow and impact resistance of the coal chutes, thereby solving the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A structure for reinforcing and repairing the surrounding rock of an underground coal chute includes several arc-shaped prefabricated support blocks, which are assembled into a ring along the circumference of the underground coal chute and fitted onto the outside of the underground coal chute.

[0009] The inner arc surface of the arc-shaped prefabricated support block fits into the inner curved surface of the underground coal chute, and the inner hole of the annular support structure after assembly is consistent with the inner diameter of the underground coal chute.

[0010] A grouting gap is formed between the arc-shaped prefabricated support block and the surrounding rock of the underground coal chute;

[0011] The grouting gap is filled with grout, which is bonded and fixed to the arc-shaped precast support block and the surrounding rock.

[0012] As a further aspect of the present invention: the thickness of the arc-shaped prefabricated support block is distributed in a medium-thick and two-thin pattern, with a maximum thickness of 10cm, an upper width of 40cm, a lower width of 20cm, and the curvature of its inner arc surface matches the curvature of the inner wall of the underground coal chute.

[0013] As a further aspect of the present invention: the arc-shaped prefabricated support block is provided with connecting steel bars inside.

[0014] As a further aspect of the present invention: the two ends of the arc-shaped prefabricated support block are provided with mortise and tenon structures for interlocking and splicing adjacent support blocks.

[0015] As a further aspect of the present invention: a lifting ring is reserved at the upper part of the arc-shaped prefabricated support block, and the lifting ring is embedded inside the support block; after the hoisting is completed, the surface of the lifting ring is sealed with concrete.

[0016] As a further aspect of the present invention: the inner arc surface of the arc-shaped prefabricated support block is provided with an impact-resistant and wear-resistant layer, which is a high-strength wear-resistant castable layer or a wear-resistant quartz sand composite mortar layer with a thickness of 8-10mm, and is integrally formed with the arc-shaped prefabricated support block during the ground prefabrication stage.

[0017] This invention also provides a method for reinforcing and repairing the surrounding rock of an underground coal chute based on the above-mentioned structure. The entire construction process involves personnel located outside the underground coal chute, and includes the following steps:

[0018] S1. Ground prefabrication: Cast arc-shaped prefabricated support blocks in the ground prefabrication yard, integrally form an impact-resistant and wear-resistant layer on its inner arc surface, arrange connecting steel bars inside, process mortise and tenon structures at both ends, reserve lifting rings at the top, and cure to the design strength.

[0019] S2. Pretreatment of surrounding rock: Clean up the broken surrounding rock and debris around the underground coal chute, repair the inner wall, mark the assembly positioning baseline, and reserve grouting gap;

[0020] S3. Directional assembly: Hoisting equipment is erected on the top of the underground coal chute to directionally lower the arc-shaped prefabricated support blocks to the design elevation, and each block is aligned with the tenon and mortise structure and spliced ​​together to form a ring support structure.

[0021] S4. Top grouting: Grouting material is injected from the top of the underground coal chute into the grouting gap and the joint of the support block from top to bottom. After the grouting material solidifies, the grouting body is bonded and fixed to the arc-shaped prefabricated support block and the surrounding rock to form an integrated reinforcement structure.

[0022] S5. Finishing treatment: After the grout has solidified, the surface of the lifting ring is sealed with concrete.

[0023] As a further embodiment of the present invention: in step S4, the grouting material is PO 42.5 ordinary silicate cement grout or cement-water glass two-component grout, the water-cement ratio of the cement grout is 0.6-0.8, the volume ratio of the cement to the water glass is 1:0.3-0.5, and the initial setting time is 3-10 minutes.

[0024] As a further aspect of the present invention: In step S4, before grouting, a grout-stopping platform is poured at the lower end of the arc-shaped precast support block and a sealing pad is laid. A sealing ring is erected at the upper end and sealed with quick-setting mortar. The grouting pressure increases in stages, with an initial grouting pressure of 0.2-0.4 MPa, a normal grouting pressure of 0.5-0.8 MPa, a maximum pressure not exceeding 1.0 MPa, and a pressure stabilization time of 3-5 minutes.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Extremely high safety: This invention overturns the traditional mode of requiring personnel to enter the coal chute for operation. The entire process of hoisting, assembling and grouting behind the wall of the support block is completed at the top of the chute and in the external safe area, completely eliminating major safety risks such as personnel falling and collapse.

[0027] 2. Stable and reliable structure: Ground prefabrication ensures the high quality and precision of the support blocks; the mortise and tenon structure enables precise and rapid assembly, forming a ring support body with good integrity; the pressure grouting technology behind the wall makes the grout body tightly bonded to the support blocks and surrounding rock, forming an integrated load-bearing structure, which completely solves the stubborn problems of "vacuuming" and "poor fit" in traditional support.

[0028] 3. Excellent support performance: Industrial tests have verified that after adopting this invention, the cumulative rock approach over 30 days is ≤20mm, which is more than 70% lower than that of traditional shotcrete support; the overall bearing capacity of the support structure is increased by more than 60%, and the impact resistance is more than twice that of ordinary concrete. The impact-resistant and wear-resistant layer set on the inner arc surface significantly improves the ability to resist long-term impact and friction from coal flow.

[0029] 4. Highly efficient and economical construction: Ground prefabrication and underground assembly are carried out simultaneously, significantly shortening underground construction time. The construction cycle for reinforcing a single section of coal chute can be reduced by more than 60%, minimizing the impact on normal mine production and resulting in significant overall economic benefits.

[0030] 5. Ensure smooth coal chute flow: The arc-shaped design and precise assembly process of the support blocks ensure a smooth transition of the inner wall of the coal chute after repair, without any structure that obstructs coal chute flow, thus guaranteeing coal transportation efficiency. Attached Figure Description

[0031] Figure 1 This is a three-dimensional structural diagram of a single arc-shaped concrete support block.

[0032] Figure 2 This is a schematic diagram showing the assembly effect of the annular support structure for a coal chute.

[0033] Figure 3 This is a top view schematic diagram of the coal chute support structure of the present invention.

[0034] Figure 4 for Figure 1 The image shows a side view of the arc-shaped concrete support block.

[0035] Figure 5 for Figure 1 The front view of the arc-shaped concrete support block shown.

[0036] In the diagram: 1. Concrete support block; 2. Connecting steel bars; 3. Mortise and tenon structure; 4. Reserved lifting ring; 5. Coal chute; 6. Grouting gap. Detailed Implementation

[0037] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0038] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0039]

Example

[0040] I. Project Overview

[0041] Taking the reinforcement and repair project of a coal chute in a coal mine as an example, the coal chute is 15m deep, with an upper diameter of 2.2m and a lower diameter of 1.8m. The surrounding rock is mainly broken sandy mudstone, with obvious spalling and collapse in some areas, and it urgently needs reinforcement and repair.

[0042] II. Strengthening and Repairing the Structure

[0043] Please see Figures 1 to 5The reinforcement and repair structure used in this embodiment mainly includes 12 arc-shaped precast concrete support blocks 1. These 12 concrete support blocks 1 are assembled circumferentially along the underground coal chute 5 to form a complete annular support body, which is fitted inside the underground coal chute 5. The inner arc surface of the concrete support block 1 completely matches the curved surface of the inner wall of the underground coal chute 5, and after assembly, the inner diameter of the annular support body is consistent with the inner diameter of the underground coal chute 5. A grouting gap 6 of approximately 3-5 cm is formed between the concrete support block 1 and the surrounding rock. This grouting gap 6 is filled with a cement-water glass dual-liquid grout, which solidifies to form an integrated reinforcement structure.

[0044] The specific structure of concrete support block 1 is as follows:

[0045] Matrix material: C35 high-strength concrete was used for casting.

[0046] Geometric dimensions: The thickness is distributed in the middle and thin at both ends, with a maximum thickness of 10cm, a top width of 40cm, a bottom width of 20cm, and the arc length is calculated based on the circumference of the coal chute.

[0047] Connecting steel bar 2: Cold-rolled ribbed steel mesh with a diameter of 6mm is evenly distributed inside.

[0048] Mortise and tenon structure 3: The two ends are respectively provided with protruding tenons and concave tenons for interlocking adjacent blocks.

[0049] Reserved lifting ring 4: A lifting ring made of Φ12mm high-strength round steel is pre-embedded in the upper part and embedded in the concrete support block 1.

[0050] Impact-resistant and wear-resistant layer: The inner arc surface is provided with an integrally formed wear-resistant quartz sand composite mortar layer with a thickness of 10mm. The inner arc surface is pre-roughened and coated with an interface agent to ensure bonding strength.

[0051] III. Reinforcement and Repair Construction Methods

[0052] The specific construction steps are as follows:

[0053] The first step is ground prefabrication.

[0054] At the ground prefabrication yard, standardized steel molds were used to pour concrete support blocks 1. First, connecting steel bars 2 and pre-installed lifting rings 4 were placed, followed by pouring C35 concrete. After the concrete initially set, the inner curved surface was roughened and coated with an interface agent. Then, a 10mm thick layer of wear-resistant quartz sand composite mortar was laid, smoothed, and polished to match the curvature of the mold. After 28 days of standard curing, 12 concrete support blocks 1 were transported to the vicinity of the upper entrance of the underground coal chute 5 for later use.

[0055] The second step is the pretreatment of the surrounding rock in the coal chute.

[0056] The loose coal, loose rocks, and broken surrounding rock at the top and inner wall of the underground coal chute 5 were manually removed. A pneumatic grinder was used to smooth the inner wall, making it roughly flat. Based on the circumference of the chute and the width of the concrete support blocks 1, the vertical assembly positioning baseline for each concrete support block 1 was marked on the shaft wall with red paint. During the cleaning process, a natural gap of approximately 3-5 cm was maintained between the concrete support block 1 and the surrounding rock as a grouting gap 6.

[0057] The third step is the targeted placement and assembly of the support blocks.

[0058] A 5-ton winch was securely erected directly above the underground coal chute 5, and guide pulleys and guide ropes were installed. An operator, positioned in a safe area at the top of the chute, used a pre-installed lifting ring 4 to hook the first concrete support block 1 onto the winch hook. Using the guide rope, it was slowly lowered to the pre-constructed support steps at the bottom of the chute. Its elevation and center position were checked using a laser pointer, and after confirmation, it was secured with a temporary rope. Subsequently, the remaining concrete support blocks 1 were lowered sequentially. Each lowered block was aligned with the tenon and mortise structure 3 of the adjacent block, allowing them to naturally interlock using their own weight, until all 12 blocks were assembled, forming a complete ring-shaped support structure. After assembly, an inspection confirmed that the inner hole of the ring-shaped support structure was smooth, without protrusions or obvious misalignments. Throughout the entire process, no personnel entered the interior of the coal chute 5.

[0059] The fourth step is to perform pressure grouting from top to bottom.

[0060] First, sealing is carried out: at the lower end of the ring support structure, a ring of C30 quick-setting concrete is poured to stop the grouting, and a rubber sealing gasket is laid. At the upper end, an adjustable steel sealing ring is erected, and the gap between the ring and the concrete support block 1 and the surrounding rock is filled with quick-setting mortar, so that the grouting gap 6 forms a closed cavity.

[0061] Then, the grouting material was prepared: a cement-water glass two-component grout was prepared on-site. P.O42.5 ordinary Portland cement was used, with a water-cement ratio controlled at 0.7:1. The cement grout was mixed with water glass of modulus 2.8 and Baume degree 40 at a volume ratio of 1:0.4, and the measured initial setting time was 5 minutes.

[0062] Finally, perform the grouting operation: Insert the grouting gun head into the top of the grouting gap 6 from the upper opening of the coal chute 5. Start the grouting pump and use a staged pressure increase method for grouting. The initial grouting pressure is controlled at 0.3 MPa, and after the pressure stabilizes, it is gradually increased to the normal grouting pressure of 0.6 MPa, with the maximum pressure not exceeding 1.0 MPa. Carefully observe the grout return situation at the lower port grout stop platform. After about 8 minutes, thick grout consistent with the injected grout flows out of the lower port grout return hole, and the pressure gauge shows a stable 0.6 MPa. At this time, immediately close the grouting pipe valve, seal the orifices of the upper and lower ports, and maintain stable pressure for 5 minutes.

[0063] After the grout solidifies, the grout body densely fills the grouting gaps 6 and all splicing joints, firmly bonding the concrete support block 1 and the surrounding rock into a whole. The entire grouting process is completed from the top, and personnel do not need to enter the coal chute 5.

[0064] The fifth step is the final finishing touches.

[0065] After the grout has solidified for 24 hours, the pre-reserved lifting rings 4 exposed on the upper surface of the concrete support block 1 are sealed and smoothed with quick-setting concrete. Finally, an endoscope is used to thoroughly inspect the inner surface of the ring support structure to confirm that the inner surface is smooth and does not obstruct the coal chute. The site is then cleaned up, and the construction is complete.

[0066] IV. Application Effects

[0067] The repaired coal chute 5 was monitored for three months, and the results are as follows:

[0068] Rock stability: 30 days after support, the maximum cumulative radial approach of the surrounding rock was 15mm, which is much smaller than that of traditional methods (usually ≥60mm), indicating good rock integrity.

[0069] Structural bearing capacity: Indoor bending tests were conducted on precast blocks from the same batch, and their ultimate bearing capacity was increased by 65% ​​compared with that of traditional C30 plain concrete specimens.

[0070] Impact resistance: Simulated coal impact tests show that the support structure of the present invention can withstand 2,000 standard coal impacts without structural damage, and its impact resistance is 2.5 times that of ordinary C30 concrete.

[0071] Construction efficiency: From assembly to grouting completion, the total time is only 6 hours, which shortens the cycle by more than 75% compared to the traditional cast-in-place concrete method (which usually takes 2-3 days).

[0072] Safety benefits: The entire construction process achieved "zero entry" and no personal safety risks.

[0073] The present invention provides a structure and method for reinforcing and repairing the surrounding rock of underground coal chutes. It employs a prefabrication method on the ground and rapid assembly underground, significantly shortening underground operation time and reducing the risk to personnel entering the coal chute. The mortise and tenon structure 3 enables precise splicing of the concrete support blocks 1, ensuring the integrity of the ring support. Subsequent grouting behind the wall ensures complete adhesion between the concrete support blocks 1 and the surrounding rock, enabling them to share the load. This significantly improves the impact and deformation resistance of the surrounding rock in the coal chute and coal outlet, solving the problems of poor adhesion, instability, and complex construction associated with traditional supports. It can be widely applied in coal mines, metal mines, and other projects requiring underground coal chutes and ore discharge. The construction method is simple, safe, and reliable; the reinforced and repaired structure is stable and durable, demonstrating significant practical value and promising prospects for wider application.

[0074] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A structure for reinforcing and repairing the surrounding rock of an underground coal chute, characterized in that, It includes several arc-shaped prefabricated support blocks, which are assembled into a ring along the circumference of the underground coal chute and fitted onto the outside of the underground coal chute. The inner arc surface of the arc-shaped prefabricated support block fits into the inner curved surface of the underground coal chute, and the inner hole of the annular support structure after assembly is consistent with the inner diameter of the underground coal chute. A grouting gap is formed between the arc-shaped prefabricated support block and the surrounding rock of the underground coal chute; The grouting gap is filled with grout, which is bonded and fixed to the arc-shaped precast support block and the surrounding rock.

2. The underground coal chute surrounding rock reinforcement and repair structure according to claim 1, characterized in that, The thickness of the arc-shaped prefabricated support block is distributed with a medium thickness and thin edges, with a maximum thickness of 10cm, an upper width of 40cm, a lower width of 20cm, and the curvature of its inner arc surface matches the curvature of the inner wall of the underground coal chute.

3. The underground coal chute surrounding rock reinforcement and repair structure according to claim 2, characterized in that, The arc-shaped prefabricated support block is internally reinforced with connecting steel bars.

4. The underground coal chute surrounding rock reinforcement and repair structure according to claim 3, characterized in that, The two ends of the arc-shaped prefabricated support block are provided with mortise and tenon structures for interlocking and splicing adjacent support blocks.

5. The underground coal chute surrounding rock reinforcement and repair structure according to claim 4, characterized in that, The upper part of the arc-shaped prefabricated support block is reserved with a lifting ring, which is embedded inside the support block; after the hoisting is completed, the surface of the lifting ring is sealed with concrete.

6. The underground coal chute surrounding rock reinforcement and repair structure according to claim 1, characterized in that, The inner arc surface of the arc-shaped precast support block is provided with an impact-resistant and wear-resistant layer. The impact-resistant and wear-resistant layer is a high-strength wear-resistant castable layer or a wear-resistant quartz sand composite mortar layer with a thickness of 8-10mm. It is integrally formed with the arc-shaped precast support block during the ground prefabrication stage.

7. A method for reinforcing and repairing the surrounding rock of an underground coal chute, applied to the underground coal chute surrounding rock reinforcement and repair structure described in any one of claims 1-6, characterized in that, Throughout the construction process, personnel are located outside the underground coal chute, including the following steps: S1. Ground prefabrication: Cast arc-shaped prefabricated support blocks in the ground prefabrication yard, integrally form an impact-resistant and wear-resistant layer on its inner arc surface, arrange connecting steel bars inside, process mortise and tenon structures at both ends, reserve lifting rings at the top, and cure to the design strength. S2. Pretreatment of surrounding rock: Clean up the broken surrounding rock and debris around the underground coal chute, repair the inner wall, mark the assembly positioning baseline, and reserve grouting gap; S3. Directional assembly: Hoisting equipment is erected on the top of the underground coal chute to directionally lower the arc-shaped prefabricated support blocks to the design elevation, and each block is aligned with the tenon and mortise structure and spliced ​​together to form a ring support structure. S4. Top grouting: Grouting material is injected from the top of the underground coal chute into the grouting gap and the joint of the support block from top to bottom. After the grouting material solidifies, the grouting body is bonded and fixed to the arc-shaped prefabricated support block and the surrounding rock to form an integrated reinforcement structure. S5. Finishing treatment: After the grout has solidified, the surface of the lifting ring is sealed with concrete.

8. The method for reinforcing and repairing the surrounding rock of an underground coal chute according to claim 7, characterized in that, In step S4, the grouting material is PO 42.5 ordinary silicate cement grout or cement-water glass two-component grout. The water-cement ratio of the cement grout is 0.6-0.8, the volume ratio of cement to water glass is 1:0.3-0.5, and the initial setting time is 3-10 minutes.

9. The method for reinforcing and repairing the surrounding rock of underground coal chute according to claim 7, characterized in that, In step S4, before grouting, a grout-stopping platform is poured at the lower end of the arc-shaped precast support block and a sealing pad is laid. A sealing ring is erected at the upper end and sealed with quick-setting mortar. The grouting pressure increases in stages, with an initial grouting pressure of 0.2-0.4 MPa, a normal grouting pressure of 0.5-0.8 MPa, a maximum pressure not exceeding 1.0 MPa, and a pressure stabilization time of 3-5 minutes.

Images