Method for cooperatively controlling surrounding rock deformation through mutual inhibition of coal mine tunnel top deflection and side expansion

Abstract

The invention belongs to the field of roadway support utilization, and particularly relates to a method for improving the bearing capacity of two sides by converting stress of the two sides into surrounding rock of the two sides. The core is that the vertical pressure of the top plate is transferred to the horizontal direction of the two sides, the confining pressure of the two sides is increased, and the bearing capacity of the coal rock mass is increased, so that the bearing capacity of the two sides is improved, the roadway stability is improved, and surrounding rock deformation is controlled. According to the method, U-shaped steel is used as a whole, three-section splicing is adopted, the U-shaped steel support is high in strength and stability and meanwhile has the advantages of being convenient to carry and operate, the junction is connected and fixed through a hoop, the sliding pressure relief effect can be achieved, and the safety of roadway supporting is guaranteed. Anchor cable channel steel is used for reinforcing and stabilizing the support, high-strength slotted steel pipes are driven outside anchor cable drill holes in the two sides to reduce shearing force borne by anchor cables, the support is more stable, the channel steel is arranged in the axial direction of a roadway, point stress of the sides is conveniently changed into face stress, the roadway sides can be stabilized in a larger range, and local point stress concentration is avoided.

Description

Technical Field

[0001] The patent of this invention belongs to the field of coal mining tunnel support technology, and specifically involves a method of converting the pressure of the roof into the confining pressure of the two sides, thereby improving the bearing capacity of the two sides and ensuring the overall stability of the tunnel surrounding rock. Background Art

[0002] At present, coal is still the main energy source in my country. The stability and control of the surrounding rock of the tunnel is an important guarantee channel for safe and efficient coal mining. More than 80% of the tunnels in my country's coal mines are mining tunnels, which are generally rectangular tunnels arranged in coal seams, and undergo the whole process of excavation, stabilization, and mining. The mining stress is as high as 2 to 5 times the original rock stress, and the mining impact is strong. Problems such as large deformation of the surrounding rock and damage to the support body often occur. At present, the surrounding rock control of domestic tunnels is mainly based on various support technologies such as anchor cable support, steel support, and steel tube concrete support. Among them, the mining tunnel mainly adopts anchor cable support. Although the anchor cable support has the advantages of low cost, good effect, flexible use and less space occupation, the effect of anchor support is poor under the conditions of high ground stress, surrounding rock crushing or soft rock in deep mining, and the maintenance cost is high during the tunnel service period. The traditional metal support method mainly relies on the strength of the support structure itself to achieve support bearing, but the compressive resistance of metal materials is relatively weak, and the bearing capacity of passive support components such as metal support is limited. In addition, most passive support components have moment instability defects. When encountering high-stress tunnel conditions, the bearing stability effect of the support components is poor.

[0003] Therefore, it is necessary to design a method for controlling surrounding rock deformation by mutual suppression of bending and expansion of coal mine tunnel roof. The present invention is a method of new tunnel support support proposed on the basis of giving full play to traditional metal support. Its core is "the vertical pressure of the roof is transferred to the horizontal direction of the two sides, the confining pressure of the two sides is increased, the bearing capacity of the coal rock mass is increased, thereby improving the bearing capacity of the two sides, improving the stability of the tunnel, and controlling the deformation of the surrounding rock". The method uses U-shaped steel as a whole and adopts three-section splicing. The U-shaped steel support is not only high in strength and stability, but also convenient to carry and operate. The U-shaped steel is connected by a clamp. When the mine pressure is large, the U-shaped steel can slide relatively to avoid bending damage. Anchor cable channel steel is used to reinforce the stable support, and the ends of the anchor cables anchored on the two sides are covered with high-strength open-slit steel pipes to avoid shear damage when the mine pressure is large. The channel steel is arranged along the axial direction of the tunnel to facilitate the change of the side from point force to surface force, which is conducive to the stability of the side of the tunnel in a larger range and avoid local point stress concentration. Summary of the invention

[0004] The purpose of the present invention is to overcome the defect that traditional supports rely on their own strength to achieve support bearing, which causes deformation of surrounding rock in coal mine tunnels and insecurity and instability. A method of using a three-section assembled support design of U-shaped steel is designed to transfer the vertical pressure of the top plate to the horizontal direction of the two sides, increase the confining pressure of the two sides, thereby improving the bearing capacity of the two sides and controlling the deformation of the surrounding rock.

[0005] The present invention proposes a method for controlling surrounding rock deformation by mutual suppression of bending and expansion of coal mine tunnel roof. This technology can realize the transfer of roof pressure to the two sides, giving the two sides a confining pressure. The strength of the coal rock mass increases with the increase of the confining pressure, thereby improving the bearing capacity of the two sides. This method also adopts a three-section assembled U-shaped steel design, which saves materials and is fast in construction. The U-shaped steel is connected by a clamp. When the mine pressure is high, the U-shaped steel can slide relatively to avoid bending damage. The ends of the anchor cables anchored on the two sides are covered with high-strength slit steel pipes to avoid shear damage when the mine pressure is high.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] 1. Design the cross-sectional dimensions and support parameters of the tunnel. Analyze and determine the geometry and dimensions of the tunnel, including the width, height and cross-sectional shape of the tunnel, and consider the changes in stress state after tunnel excavation, including the release and redistribution of original rock stress. Determine the length of the anchor cable by theoretical calculation, numerical simulation or engineering analogy.

[0008] 2. Excavate a rectangular cross-section tunnel and open rectangular grooves on both sides.

[0009] 3. According to the design, the roof support is carried out. First, the anchor cable is installed, and then the roof U-shaped steel is installed, and the anchor cable is tightened and anchored. Drill holes in the tunnel roof. The rock layer interface, sliding surface height and design length should be verified during the drilling process. After installing the anchor cable into the drilled hole, the roof U-shaped steel is installed. A long groove is opened in the connecting part of the U-shaped steel so that the anchor cable can slide horizontally to prevent bending due to excessive horizontal stress. Grouting or other anchoring agents are injected into the drilled hole to fill the hole pores, and finally the anchor cable is tightened to make the U-shaped steel roof and the anchor cable tightly combined. The top arch beam can be designed according to different mine pressure conditions. If you want to make the two sides more stable, you can make the angle between the bracket and the horizontal smaller, so as to obtain a greater confining pressure.

[0010] 4. Carry out two-side support, first drive the anchor cable, then install the high-strength slotted steel pipe, install the "concrete block + channel steel + wooden board", and tighten the anchor after installing the pallet. Drill holes in the rectangular grooves opened on the two sides and drive the anchor cable in. Put high-strength slotted steel pipes on the ends of the anchor cables anchored on the two sides to avoid shear damage when the mine pressure is high. Then install the concrete block, channel steel and wooden board in sequence. Tighten the anchor after installing the pallet.

[0011] 5. Clamp the top U-shaped steel and the two U-shaped steels, and tighten them with clamps. Put the two U-shaped steels in and weld them firmly with the two channel steels. The middle U-shaped steel bracket overlaps the U-shaped steel brackets on both sides, and the overlapping parts are connected with clamps. If the pressure is too high, the overlapping brackets can slide relative to each other to relieve the pressure and avoid bending damage.

[0012] 6. Dynamically monitor the deformation of the tunnel and support structure, and locally reinforce the areas with large deformation. After the installation of the U-shaped steel support, conduct a quality inspection to ensure that the support effect meets the requirements. Take necessary protective measures, such as setting up guardrails and warning signs, to prevent accidental collisions or damage during construction and protect the integrity of the support. At the same time, carry out dynamic monitoring to promptly discover and deal with potential safety hazards, locally reinforce the areas with large deformation, and improve the stability and safety of the overall structure.

[0013] Compared with traditional metal stent support, the present invention has the following advantages:

[0014] First, the vertical pressure of the roof can be transferred to the horizontal direction of the two sides, giving the two sides a confining pressure. The strength of the coal rock mass increases with the increase of the confining pressure, and the confining pressure of the tunnel changes from uniaxial to triaxial, which can improve the bearing capacity of the two sides and reduce the deformation of the confining pressure and a series of safety hazards. In addition, different arch beam angles can be designed according to different mine pressure conditions. If you want to make the two sides more stable, you can reduce the horizontal angle of the support to obtain a better confining pressure.

[0015] Second, use anchor cables to reinforce and stabilize the bracket. Insert slit anti-shear steel pipes outside the two anchor cable holes to reduce the shear force on the anchor cables and make the bracket more stable. Arrange channel steel along the axial direction of the tunnel to change the side force from point force to surface force.

[0016] It is beneficial to the stability of the tunnel side in a larger area and avoid stress concentration at local points.

[0017] Third, the overall bracket adopts U-shaped steel bracket design, which is easy to carry, high strength, safer and more stable than other materials. It is divided into three sections for easy operation, easy installation and removal, short construction period and fast construction; the overlapping parts are connected by clamps. If the pressure is too high, the overlapping parts of the bracket can slide relative to each other to relieve the pressure, which improves safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A method for controlling surrounding rock deformation by mutual suppression of roof bending and wall expansion in coal mine tunnels

[0019] Figure 2 Top U-shaped steel support structure diagram

[0020] Figure 3 Details of the two side anchor cable channels

[0021] Figure 4 U-shaped steel bracket clamp connection details

[0022] Figure 5 Process flow chart

[0023] The components in the attached figure are marked as follows: 1. Anchor cable outer jacket steel pipe, 2. Anchor cable, 3. Left U-shaped steel bracket, 4. Middle U-shaped steel bracket, 4.1 top slot, 5. Right U-shaped steel bracket, 6. Two side slots, 7. Two side anchor cables, 8. Precast concrete block, 9. Steel strand, 10. Channel steel, 11. Tray, 12. Clamp DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] 1. Design the cross-sectional dimensions and support parameters of the tunnel. Analyze and determine the geometry and dimensions of the tunnel, including the width, height and cross-sectional shape of the tunnel, and consider the changes in stress state after tunnel excavation, including the release and redistribution of original rock stress. Determine the length of the anchor cable by theoretical calculation, numerical simulation or engineering analogy.

[0026] 2. Excavate a rectangular cross-section tunnel and open rectangular grooves 6 on both sides.

[0027] 3. According to the design, the roof support is carried out. First, the anchor cable is driven, and then the roof U-shaped steel is installed, and the anchor cable is tightened and anchored. Drill holes in the tunnel roof. During the drilling process, the rock layer interface, the sliding surface height and the designed length should be verified. After installing the anchor cable 2 into the drilled hole, the roof U-shaped steel 4 is installed. A long groove 4.1 is opened in the connecting part of the U-shaped steel so that the anchor cable can slide horizontally to prevent bending due to excessive horizontal stress. Grouting or other anchoring agents are injected into the borehole to fill the hole pores, and finally the anchor cable 2 is tightened to make the U-shaped steel roof 4 tightly combined with the anchor cable. The top arch beam can be designed according to different mine pressure conditions. If you want to make the two sides more stable, you can make the angle between the bracket and the horizontal smaller, so as to obtain a greater confining pressure.

[0028] 4. Carry out two-side support, first drive the anchor cable, then install the high-strength slotted steel pipe, install the "concrete block + channel steel + wooden board", and tighten and anchor after installing the pallet. Drill holes in the rectangular grooves 6 opened on the two sides and drive the anchor cable 7 into them. Put the high-strength slotted steel pipe 1 on the ends of the anchor cables anchored on the two sides to avoid shear damage when the mine pressure is large. Then install the concrete block 8, channel steel 10 and wooden board in sequence. After installing the pallet 11, tighten and anchor.

[0029] 5. Clamp the top U-shaped steel and the two U-shaped steels, connect them with the clamp 12, and tighten the bolts. Put the two U-shaped steels 3 and 5 in and weld them firmly with the two channel steels 10. The middle U-shaped steel bracket 4 overlaps the two U-shaped steel brackets 3 and 5. The overlapping parts are connected with the clamp 12. If the pressure is too large, the overlapping parts of the brackets can slide relative to each other to relieve the pressure and avoid bending damage.

[0030] 6. Dynamically monitor the deformation of the tunnel and support structure, and locally reinforce the areas with large deformation. After the installation of the U-shaped steel support, conduct a quality inspection to ensure that the support effect meets the requirements. Take necessary protective measures, such as setting up guardrails and warning signs, to prevent accidental collisions or damage during construction and protect the integrity of the support. At the same time, carry out dynamic monitoring to promptly discover and deal with potential safety hazards, locally reinforce the areas with large deformation, and improve the stability and safety of the overall structure.

Claims

1. A method for controlling surrounding rock deformation by mutual suppression of roof bending and wall expansion in coal mine tunnels, characterized in that The vertical pressure of the tunnel roof is transferred to the horizontal confining pressure of the two sides. Since the bearing capacity of the coal rock mass increases with the increase of the confining pressure, the invention can significantly improve the bearing capacity of the two sides. The U-shaped steel is connected by a clamp. When the mine pressure is large, the U-shaped steel can slide relatively to avoid bending damage. The ends of the anchor cables anchored on the two sides are covered with high-strength slit steel pipes to avoid shear damage when the mine pressure is large. The specific implementation includes the following steps: (a) Design tunnel cross-sectional dimensions and support parameters. (b) Excavate a rectangular cross-section tunnel and open rectangular grooves on both sides of the tunnel. (c) According to the design, the top plate is supported by first driving the anchor cables, then installing the top plate U-shaped steel, and tightening and anchoring the anchor cables. (d) Carry out two-sided support, first install the anchor cable, then install the cut anti-shear steel pipe, install the "concrete block + channel steel + wooden board", and then tighten the anchor after installing the pallet. (e) Clamp the top plate U-shaped steel and the two side U-shaped steels and tighten them with clamps. (f) Dynamically monitor the deformation of tunnels and support structures, and perform local reinforcement on areas with large deformation.

2. A method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in a coal mine tunnel as claimed in claim 1, characterized in that The inclination angle of the top plate anchor cable to the two sides is generally in the range of 30° to 45°, and the length is generally 6.3m to 8.3m, ensuring that the anchor end is located above the two sides to avoid shear instability of the top plate.

3. A method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in coal mine tunnels as claimed in claim 1, characterized in that The two sides of the anchor cables are arranged in the middle, and a slit steel pipe with a length of about 1.5m to 2.0m is sleeved on the ends, and the diameter of the steel pipe is 2mm to 5mm larger than the diameter of the anchor cable.

4. A method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in a coal mine tunnel as claimed in claim 1, characterized in that A long groove is opened at the connection between the top plate U-shaped steel and the anchor cable, with a general length ranging from 10cm to 20cm. When the horizontal stress is too large, the anchor cable can move horizontally to prevent the U-shaped steel from bending and becoming unstable.

5. The method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in coal mine tunnels as claimed in claim 1 is characterized in that The two sides of the anchor cables are connected with channel steel, and every three rows of anchor cables are grouped together, which can increase the effective area of ​​the top plate transferred to horizontal confining pressure and improve the overall stability of the tunnel.

6. A method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in a coal mine tunnel as claimed in claim 1, characterized in that The U-shaped steel support is assembled from three parts. The overlapping parts of the U-shaped steel support at the shoulder angle of the tunnel are connected with clamps. The length of the overlapping part is generally 30cm to 50cm. When the mine pressure is high, the U-shaped steel can slide relatively to avoid bending damage.

7. A method for controlling surrounding rock deformation by mutual suppression of roof deflection and wall expansion in a coal mine tunnel as claimed in claim 1, characterized in that The U-shaped steel used for tunnel support is selected according to the mining depth. Conventional mining depth generally uses 25U or 29U steel, and deep mining generally uses 36U steel.

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