Large-section closed wall forming process

Abstract

The large-section sealing wall forming process comprises the steps that S1, multiple rows of channel steel anchor cables are constructed on a roadway top plate in the advancing direction, each row comprises two sets of channel steel anchor cables, and multiple sets of reinforcing anchor rods are constructed on a roadway bottom plate; and S2, the ultrahigh large-section dismounting and mounting chamber section is backfilled with coal gangue to restore to the original tunneling section, and compaction is conducted through a vibration or crawler belt transport vehicle compaction technology. According to the invention, through the reinforcement of the top plate, the sinking force of the top plate can be counteracted through the prestress diffusion effect, and concentrated stress is converted into uniformly distributed load; through the synergistic effect of the grouting body and the anchor rod, a composite reinforcing layer is formed, surrounding rock and floor heaving are effectively prevented, the compaction degree is enhanced through the vibration and crawler belt transport vehicle compaction technology, the elasticity modulus of the backfill body reaches 200-300 MPa through the self-stability and gradation characteristics of coal gangue, and ground stress transmission is effectively buffered; the problems of cracking and deformation of the sealing wall caused by gravity and ground stress of the surrounding rock are effectively solved, and the method is suitable for deep high-stress roadway supporting and sealing wall construction.

Description

Technical Field

[0001] This invention relates to the field of coal mine tunnel engineering technology, and more specifically to the forming process of large-section sealed walls. Background Technology

[0002] During the mining process, high ground stress can have multiple effects on the deformation of the surrounding rock in the roadways near the goaf: 1. It leads to the expansion of the plastic zone of the surrounding rock: When the stress on the surrounding rock of the roadway near the goaf exceeds its yield strength, the surrounding rock enters a plastic state and the range of the plastic zone continues to expand; this will weaken the bearing capacity of the surrounding rock and make the roadway more prone to deformation and damage. 2. Increased deformation of surrounding rock: High ground stress can cause significant deformation of the surrounding rock in the roadway, including roof subsidence, floor bulging, and sidewall convergence. Near the goaf, due to the disruption of the original rock stress balance, high ground stress will further promote the deformation and displacement of the surrounding rock into the roadway, thereby affecting the normal use and maintenance of the roadway.

[0003] 3. Causes surrounding rock fracturing and instability: High ground stress may cause cracks to form inside the surrounding rock and continue to expand, destroying the integrity of the surrounding rock. Under the influence of goaf, this fracturing phenomenon may be more obvious, thereby reducing the stability of the surrounding rock, increasing the risk of roadway collapse, and affecting construction safety, efficiency and the overall performance of the sealing wall.

[0004] 4. Changes in the deformation characteristics of surrounding rock: High ground stress can change the deformation characteristics of surrounding rock, such as changing from elastic deformation to plastic deformation, and the deformation rate will also increase. Near the goaf, due to the complexity of stress distribution, the change in the deformation characteristics of surrounding rock may be more significant, bringing greater difficulties to roadway support.

[0005] In fields such as coal mining and underground engineering, the installation of airtight walls is crucial. They can effectively isolate harmful gases, prevent the spread of fire, and ensure the safety of the working environment. Traditional airtight wall construction techniques have problems such as long construction cycles and poor overall integrity, especially for airtight walls with large cross-sections. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to avoid cracking and deformation of the sealed wall caused by gravity and ground stress in the surrounding rock of large cross-section tunnels.

[0007] This invention solves the above-mentioned technical problems through the following technical means: a large-section sealed wall forming process, comprising: S1. Construct multiple rows of channel steel anchor cables on the roof of the tunnel along the direction of travel, with two sets per row, and construct multiple sets of reinforcing anchor bolts on the floor of the tunnel. S2. The ultra-high cross-section dismantling chamber section is backfilled with coal gangue to restore it to the original tunneling cross-section and compacted using a vibratory or tracked transport vehicle compaction process. S3. Construction explosion-proof wall and cast-in-place wall. A metal frame is arranged vertically in the same section of the cast-in-place wall. The metal frame includes two rows of four layers of anchor rods. S4. Construct multiple rows of grouting boreholes in the bottom slab of the backfill section of the roadway, with one row of grouting boreholes every 5m, and multiple grouting boreholes in each row; construct multiple rows of grouting boreholes within 2.5m outside the explosion-proof wall and the cast-in-place wall, with each row of grouting boreholes including multiple grouting boreholes; and perform shotcreting on the sidewalls facing the goaf within 5m outside the sealed wall.

[0008] As a preferred technical solution, in S1, four rows of channel steel anchor cables are installed on the roof of roadway 1, with two sets in each row, forming a composite beam. The roof of the roadway is connected to the channel steel anchor cables to form a composite beam, thereby reinforcing the roof of the roadway.

[0009] As a preferred technical solution, the roadway floor reinforcement shall be arranged with no less than three sets of reinforcement anchor bolts, with an interval of 5m between adjacent rows of grouting boreholes, each row of grouting boreholes including three grouting boreholes, the depth of the grouting boreholes being 2m, and the grouting pressure being 3-5MPa.

[0010] As a preferred technical solution, the backfill height in S2 is about 3.5m away from the top slab, and a perforated pipe is pre-embedded to grout the bottom slab.

[0011] As a preferred technical solution, grouting holes are constructed in a row every 5m, with three grouting holes in each row. At the joint between the anchor rods of the metal frame, iron wire is used to bind and fix it to the original mesh, anchor rod, or anchor cable.

[0012] As a preferred technical solution, the cast-in-place wall is set at a position inside the tunnel, facing inward from the track guide door. The cast-in-place wall includes masonry blocks and concrete filling wall. The concrete filling wall is 4m thick. The lower half of the wall has masonry blocks on both sides as anti-gable walls. The outer slope groove of the outer masonry block anti-gable wall is provided with a cast-in-place bottom section.

[0013] As a preferred technical solution, the sealed wall is equipped with nine pipelines, namely two observation pipes, two measure pipes, one water discharge pipe, two extraction pipes, one grouting pipe, and one nitrogen injection pipe. The two observation pipes are observation pipe one and observation pipe two, the two measure pipes are measure pipe one and measure pipe two, and the two extraction pipes are the original extraction pipe and the extraction pipe.

[0014] As a preferred technical solution, gate valves are installed on all pipelines, and the pipeline gate valves are led to the outside of the fence outside the enclosed wall.

[0015] As a preferred technical solution, measure pipe one is installed at the top of the roadway, and measure pipe two is installed at the top of the roadway.

[0016] As a preferred technical solution, the grout diffusion radius is >1.5m and the filling rate is >85%.

[0017] The beneficial effects of this invention are as follows: (1) In this invention, by strengthening the roof plate, the prestress diffusion effect can offset the roof plate settlement force and convert the concentrated stress into a uniform load. Compared with traditional anchor bolts, the shear strength of the channel steel anchor cable is increased by about 40%, and the ultimate bearing capacity is more than 350kN. Through the synergistic effect of the grouting body and the anchor bolt, a composite reinforcement layer is formed, which effectively prevents the surrounding rock and bottom heave. The compaction degree is enhanced by using vibration and tracked transport vehicle compaction technology. By utilizing the self-stabilization and gradation characteristics of coal gangue, the elastic modulus of the backfill body reaches 200-300MPa, which effectively buffers the transmission of ground stress. The anchor bolts or anchor cable skeleton built into the wall effectively avoid the problem of cracking and deformation of the sealed wall caused by gravity and ground stress in the surrounding rock, which is suitable for deep high-stress roadway support and sealed wall construction. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of tunnel 1 provided in an embodiment of the present invention; Figure 2 Provided for embodiments of the present invention Figure 1 A schematic diagram of the AA cross-sectional structure, where A is the direction of the cut; Figure 3 This is a schematic diagram of the cable arrangement for the channel steel in the roadway roof provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the grouting borehole layout for the tunnel floor provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the reinforced anchor bolt structure for the tunnel floor provided in an embodiment of the present invention; Reference numerals: 1. Tunnel; 2. Explosion-proof wall; 3. Cast-in-place wall; 4. Pipeline; 41. Measure pipe one; 42. Observation pipe one; 43. Original extraction pipe; 44. Original grouting pipe; 45. Original nitrogen injection pipe; 46. Water discharge pipe; 47. Extraction pipe; 48. Observation pipe two; 49. Measure pipe two; 5. Anchor frame; 6. Block anti-gable wall; 7. Cast-in-place bottom section; 8. Backfill section; 9. Direction anchor cable; 10. Channel steel; 11. Grouting borehole; 12. Reinforced anchor. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figure 1 , Figure 2 , Figure 5 Large-section sealed wall forming process, including: S1. The roof of tunnel 1 is constructed with multiple rows of channel steel anchor cables, with two sets per row. In this embodiment, four rows of channel steel anchor cables are constructed on the roof of tunnel 1. Among them, the roof of tunnel 1 is fixedly connected with directional anchor cables 9. The directional anchor cables 9 and channel steel 10 are fixedly connected to form a composite beam. It should be noted that in this embodiment, the channel steel 10 is set along the direction of tunnel 1. The bottom slab of tunnel 1 is constructed with multiple sets of reinforcing anchor bolts 12. In this embodiment, more than four sets of reinforcing anchor bolts 12 are constructed. Four rows of channel steel anchor cables were installed on the roof of tunnel 1. The prestress diffusion effect offset the roof settlement force and transformed the concentrated stress into a uniformly distributed load. Compared with traditional anchors, the shear strength of the channel steel anchor cables is increased by about 40%, and the ultimate bearing capacity is over 350kN. Multiple sets of reinforcing anchor bolts 12 are arranged to reinforce the bottom slab of tunnel 1, in conjunction with three-hole grouting boreholes 11 spaced 5m apart. The depth of the grouting boreholes 11 is 2m, and the grouting pressure is 3-5MPa. Through the synergistic effect of the grout and the anchor bolts, a composite reinforcement layer is formed, which effectively prevents the surrounding rock and bottom heave, and the amount of bottom heave is significantly reduced. S2. The ultra-high cross-section dismantling chamber section is backfilled with coal gangue to restore it to the original tunneling cross-section and compacted. The backfill height is about 3.5m away from the roof, and perforated pipes are pre-embedded to grout the bottom plate. Vibration and tracked transport vehicle compaction technology is used to enhance the compaction degree. By utilizing the self-stabilizing and gradation characteristics of coal gangue, the elastic modulus of the backfill body reaches 200-300MPa, effectively buffering the transmission of ground stress. S3, construction explosion-proof wall 2 and cast-in-place wall 3; S4. Construct multiple rows of grouting boreholes 11 in the bottom slab of the backfill section 8 of tunnel 1. In this embodiment, the grouting boreholes 11 are constructed in a row every 5m, with three grouting boreholes 11 in each row; construct multiple rows of grouting boreholes 11 in the top and bottom slabs within a 2.5m range outside the sealed wall. In this embodiment, the sealed wall includes an explosion-proof wall 2 and a cast-in-place wall 3, which are spaced at a certain distance. (See reference...) Figure 4 Within a 2.5m radius outside both the explosion-proof wall 2 and the cast-in-place wall 3, three rows of grouting holes 11 are constructed, with each row of grouting holes 11 consisting of three grouting holes 11; shotcrete reinforcement is carried out within a 5m radius outside the sealed wall. In particular, two rows of four layers of anchor rods are arranged vertically in the same section of the cast-in-place wall 3 to form a metal skeleton; at the joint of the anchor rods, 12# iron wire is used to tie and connect them to the original mesh or anchor rod or anchor cable. The grout diffusion radius is >1.5m and the filling rate is >85%, which effectively enhances the density of the top and bottom plates. Within 5m of the sealed wall facing the goaf, grout is sprayed to reinforce it. The thickness of the sprayed grout layer is ≥100mm and the compressive strength is C30, forming a dual protection system of grouting consolidation zone and sprayed layer protection zone, which improves the integrity coefficient of the surrounding rock. See Figure 2 Explosion-proof wall 2 is built at the drilling site inside the track, with a wall thickness of 4m. Metal mesh is hung on the outside of the wall and shotcrete is applied. In the tunnel 1, a block and concrete filling wall is built at a designated position inward from the track door. The block and concrete filling wall form a cast wall 3. The concrete filling wall is 4m thick. On both sides of the lower half of the wall, a 0.6m wide block anti-gable wall 6 is built. The outer slope groove of the outer block anti-gable wall 6 is equipped with a cast-in-fill section 7.

[0021] See Figure 1 , Figure 2 Nine pipelines 4 are laid on the sealed wall, including two observation pipelines, two control pipelines, one water discharge pipeline 46, two extraction pipelines, one grouting pipeline, and one nitrogen injection pipeline. All pipelines 4 are made of seamless iron pipes and are equipped with gate valves. The gate valves of pipelines 4 lead to the fence outside the sealed wall. Among them, the two observation pipelines are observation pipeline 1 42 and observation pipeline 2 48, the two control pipelines are control pipeline 1 41 and control pipeline 2 49, the two extraction pipelines are the original extraction pipeline 43 and extraction pipeline 47, the grouting pipeline is the original grouting pipeline 44, and the nitrogen injection pipeline is the original nitrogen injection pipeline 45. The measure pipe 41 is led out 2m inside the explosion-proof wall 2, and extends to at least 3.5m outside the cast wall 3 to install a gate valve, which is installed on the top of the tunnel 1; The observation tube 42 is led out 2m inside the explosion-proof wall 2, and extends to at least 3.5m outside the cast wall 3 to install a gate valve and a measuring nozzle, which is installed at two-thirds of the height of the tunnel 1. The original extraction pipe 43 is led out 2m inside the explosion-proof wall 2, and a DN250 butterfly valve is installed 3.5m outside the poured wall 3; a flower cap is installed at the end of the pipe inside the wall; The original grouting pipe 44 was led out from the goaf area and a gate valve was installed 3.5m outside the cast wall 3; The original nitrogen injection pipe 45 was led out from the goaf and a gate valve was installed 3.5m outside the cast wall 3; The water pipe 46 is led out 1m inside the cast wall 3 and extends to at least 3.5m outside the cast wall 3 to install a gate valve and a U-shaped water seal. The inner end of the pipe is a perforated pipe 500mm away from the bottom. Extraction pipe 47 is led out 5m inside the cast-in-place wall 3, and a DN250 butterfly valve is installed 3.5m outside the cast-in-place wall 3. Later, it will connect with #3. The 273mm gas pipe is joined together, and a decorative cap is installed at the end of the pipe inside the wall.

[0022] Observation pipe 248 is led out 1m inside the cast wall 3, and extends to at least 3.5m outside the cast wall 3 to install a gate valve and a measuring nozzle, which is installed at two-thirds of the height of the tunnel 1. The second pipe 49 is led out 1m inside the cast wall 3 and extends to at least 3.5m outside the cast wall 3 to install a gate valve, which is installed at the top of the tunnel 1.

[0023] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for forming large-section sealed walls, characterized in that, include: S1. Construct multiple rows of channel steel anchor cables on the roof of the tunnel along the direction of travel, with two sets per row, and construct multiple sets of reinforcing anchor bolts on the floor of the tunnel. S2. The ultra-high cross-section dismantling chamber section is backfilled with coal gangue to restore it to the original tunneling cross-section and compacted using a vibratory or tracked transport vehicle compaction process. S3. Construction explosion-proof wall and cast-in-place wall. A metal frame is arranged vertically in the same section of the cast-in-place wall. The metal frame includes two rows of four layers of anchor rods. S4. Construct multiple rows of grouting boreholes in the bottom slab of the backfill section of the roadway, with one row of grouting boreholes every 5m, and multiple grouting boreholes in each row; construct multiple rows of grouting boreholes within 2.5m outside the explosion-proof wall and the cast-in-place wall, with each row of grouting boreholes including multiple grouting boreholes; and perform shotcreting on the sidewalls facing the goaf within 5m outside the sealed wall.

2. The large-section sealed wall forming process according to claim 1, characterized in that, In S1, four rows of channel steel anchor cables are installed on the roof of tunnel 1, with two sets in each row. The roof of the tunnel is connected to the channel steel anchor cables to form a composite beam.

3. The large-section sealed wall forming process according to claim 1, characterized in that, Three sets of reinforcement anchors are arranged to reinforce the tunnel floor. The adjacent rows of grouting boreholes are spaced 5m apart. Each row of grouting boreholes includes three grouting boreholes with a depth of 2m and a grouting pressure of 3-5MPa.

4. The large-section sealed wall forming process according to claim 1, characterized in that, In S2, the backfill height is about 3.5m away from the top slab, and pre-embedded perforated pipes are used for grouting the bottom slab.

5. The large-section sealed wall forming process according to claim 1, characterized in that, Grouting holes are drilled in a row every 5m, with three grouting holes in each row. At the joints between the anchor rods of the metal frame, wire is used to tie and fix the anchor rods to the original mesh, anchor cable, or anchor rod.

6. The large-section sealed wall forming process according to claim 1, characterized in that, The cast-in-place wall is located in the inner part of the tunnel, facing inward from the track entrance. The cast-in-place wall consists of masonry blocks and a concrete filling wall. The concrete filling wall is 4m thick. The lower half of the wall has masonry blocks on both sides as anti-gable walls. The outer slope groove of the outer masonry block anti-gable wall is equipped with a cast-in-place bottom section.

7. The large-section sealed wall forming process according to claim 1, characterized in that, The sealed wall has nine pipelines: two observation pipelines, two measure pipelines, one water discharge pipeline, two extraction pipelines, one grouting pipeline, and one nitrogen injection pipeline. The two observation pipelines are observation pipeline one and observation pipeline two. The two measure pipelines are measure pipeline one and measure pipeline two. The two extraction pipelines are the original extraction pipeline and the extraction pipeline.

8. The large-section sealed wall forming process according to claim 1, characterized in that, Gate valves are installed on all pipelines, and the gate valves are led out of the fence outside the enclosed wall.

9. The large-section sealed wall forming process according to claim 1, characterized in that, Pipeline 1 is installed at the top of the tunnel, and pipeline 2 is installed at the top of the tunnel.

10. The large-section sealed wall forming process according to claim 1, characterized in that, The grout diffusion radius is >1.5m and the filling rate is >85%.

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