Method for repairing bottom drum roadway with FRP mesh fiber reinforced cement-based composite material

Abstract

The present invention discloses a method for repairing a bottom drum roadway with FRP mesh fiber reinforced cement-based composite materials, comprising the following steps: a plurality of grooves are opened along the direction of the roadway bottom plate, and fiber reinforced cement-based composite materials are injected into the grooves; when the maximum bulging height of the roadway bottom plate (the bottom plate rock layer outside the groove) exceeds 10 cm, "bottoming" is performed; the FRP mesh is horizontally laid on the roadway bottom plate after "bottoming"; the waste gangue generated by "bottoming" is laid on the upper part of the FRP mesh fixed on the roadway bottom plate; the waste gangue is laid on the upper part of the second layer of FRP mesh erected on the laid first layer of waste gangue; the third layer of FRP mesh is laid on the waste gangue; and the fiber reinforced cement-based composite materials are injected into the waste gangue. The method for repairing a bottom drum roadway with FRP mesh fiber reinforced cement-based composite materials provided by the present invention has the advantages of simple operation and construction, and can realize the rapid repair of the bottom drum roadway.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a method for repairing a floor drum tunnel using an FRP grid fiber reinforced cement-based composite material. Background Art

[0002] Normally, after the excavation of coal mine tunnels, the roof and sides of the tunnels need to be reinforced with support forms including anchor rods and anchor cables, while the tunnel floor is generally not reinforced. Affected by mining activities, especially with the gradual increase in the depth of coal mining, the unreinforced tunnel floor rock layer will bulge upward, commonly known as tunnel floor drum. Compared with normal tunnels, the tunnel section after the floor drum will be smaller, and the undulating tunnel floor will directly affect the normal transportation and pedestrians in the mine. In particularly serious cases, the entire tunnel will be scrapped, posing a serious hidden danger to the safe and efficient production of the mine. At present, the commonly used methods for treating tunnel floor heave mainly include the following three types: 1) Temporary cleaning of the bulging part of the tunnel, referred to as "bottoming out"; 2) Reinforcement of the tunnel floor after the tunnel is excavated to improve the strength of the tunnel floor rock layer, thereby alleviating or preventing the occurrence of floor heave; 3) Stress release of the surrounding rock around the tunnel floor by means of grooving the tunnel floor, etc., to reduce the floor heave caused by stress concentration.

[0003] The traditional method of "bottoming out" to deal with tunnel floor heave has the following problems: 1) As a passive method to deal with tunnel floor heave, it cannot fundamentally improve the stress environment of the tunnel floor. Under the influence of mining stress, the tunnel floor heave phenomenon will still occur repeatedly; 2) The waste rock generated by mechanical rock breaking to deal with the floor heave needs to be transported to other locations underground, resulting in additional rock discharge.

[0004] The method of reinforcing the tunnel floor in the early stage of tunnel excavation, including anchor support, has the problem of large overall economic investment and poor governance effect. The main reason is that the tunnel excavation activity destroys the original stress balance around the tunnel, and it takes a certain amount of time for the surrounding rock stress to be redistributed to achieve the second stress balance. When the tunnel roof, two sides and bottom plate are reinforced at the same time, the stress balance process is artificially blocked, and the process of stress release originally achieved through the bottom drum is transferred to other parts of the tunnel, which affects the stability control of the surrounding rock of the tunnel roof and two sides.

[0005] The use of stress transfer and release to treat tunnel floor heave is a proactive treatment method that has achieved good practical results on site. However, the use of stress transfer and release alone cannot fundamentally improve the strength of the floor rock formation, and its treatment effect has certain limitations.

[0006] The main development direction for treating bottom drum tunnels in the future is to combine "bottoming out", strengthening support, and combining stress transfer and stress release. Considering the increase in original rock stress after the mining depth of the tunnel increases, the additional transportation workload brought by traditional support forms, and the transportation of abandoned gangue in the bottom drum tunnel, it is necessary to develop a new method for strengthening the bottom drum tunnel. By innovating the construction process and introducing new materials including fiber-reinforced polymer (FRP), a new technical approach is provided for the rapid repair of bottom drum tunnels in deep mining coal mines. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for repairing a bottom drum roadway using an FRP grid fiber reinforced cement-based composite material, which is simple to operate, convenient to construct, and can effectively control the bottom drum deformation of the roadway.

[0008] In order to achieve the above purpose, the technical solution adopted by the present invention is: a method for repairing a floor drum roadway with an FRP mesh fiber reinforced cement-based composite material, comprising the following steps:

[0009] Step 1: multiple grooves are formed on the bottom plate of the tunnel along the direction of the tunnel;

[0010] Step 2: injecting fiber-reinforced cement-based composite materials into the multiple grooves in sequence;

[0011] Step 3: When the bottom rock layer outside the groove appears to be bulging and the maximum bulging height exceeds 10 cm, a pneumatic rock drill is used to "dig up the bottom";

[0012] Step 4: Lay the FRP grid horizontally on the tunnel floor after the "bottoming out" and fix it to the tunnel floor with positioning bolts and nuts;

[0013] Step 5, laying the waste gangue produced by "bottoming out" in step 3 on the upper part of the FRP grid fixed on the bottom plate of the roadway;

[0014] Step 6: Install a second layer of FRP grid on the first layer of waste rock and fix it with nuts and positioning bolts;

[0015] Step 7, laying waste gangue on the upper part of the second layer of FRP grid;

[0016] Step 8: Lay the third layer of FRP mesh on the waste gangue and fix it on the positioning bolts through nuts;

[0017] Step nine, injecting the fiber reinforced cement-based composite material using coal gangue as aggregate onto the waste gangue laid in the middle of the FRP grid until all the gaps are filled;

[0018] Step 10: Repeat steps 4 to 9 until all filling work is completed.

[0019] Preferably, the groove has a width of 20-40 cm and a depth of 50 cm.

[0020] Preferably, one of the grooves is located at the center of the lane width, and the other two grooves are symmetrically arranged on both sides of the center of the lane width, 30-50 cm away from both sides of the lane.

[0021] Preferably, the aggregate used in the fiber-reinforced cement-based composite material is crushed coal gangue.

[0022] Preferably, the cementitious material of the fiber-reinforced cement-based composite material is fast-hardening sulphoaluminate cement.

[0023] Preferably, the fiber material of the fiber-reinforced cement-based composite material is ultra-high molecular weight polyethylene fiber.

[0024] Preferably, the water of the fiber-reinforced cement-based composite material is mine water that has been purified underground.

[0025] Preferably, the FRP grid is a honeycomb three-dimensional structure produced by an extrusion molding process.

[0026] Preferably, the matrix material of the FRP grid includes but is not limited to basalt fiber, glass fiber and carbon fiber.

[0027] Preferably, the length of the FRP mesh is the actual width of the tunnel floor, and the width of the FRP mesh is half of its length.

[0028] Preferably, the fiber-reinforced cement-based composite material can completely fill the voids in the waste gangue, and the pressure of the grouting pump used to transport the fiber-reinforced cement-based composite material shall not be less than 2 MPa.

[0029] The beneficial effects of the bottom drum tunnel reinforcement and repair method of the present invention are that a fiber reinforced composite material (FRP) grid with light and high-strength mechanical properties is used as the main reinforcement material; by opening a groove on the tunnel floor, the stress concentration of the tunnel floor can be effectively reduced, and a deformation space is provided for the stress release of the tunnel floor; the fiber reinforced cement-based composite material is sequentially injected into the groove, and the aggregate of the fiber reinforced cement-based composite material is coal gangue, the cementitious material is fast-hardening sulfoaluminate cement, and the fiber material is ultra-high molecular weight polyethylene fiber. Since fast-hardening sulfoaluminate water has high water-cement ratio, fast hardening and high early strength mechanical properties, and ultra-high molecular weight polyethylene fiber has the characteristic of large deformation, the fiber reinforced cement-based composite material prepared by adding coal gangue aggregate and underground purified mine water can usually meet normal transportation and pedestrian needs within 1 day, and realize the rapid repair of the bottom drum tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of a laneway before a bottom drum appears in an embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of a laneway after bottom drum appears in an embodiment of the present invention;

[0032] Figure 3 Schematic diagram of the construction process of grooving the tunnel floor and injecting fiber-reinforced cement-based composite materials according to an embodiment of the present invention;

[0033] Figure 4 It is a schematic diagram of the roadway floor after the roadway floor is grooved and injected with fiber-reinforced cement-based composite material in an embodiment of the present invention;

[0034] Figure 5 is a schematic diagram of an FRP mesh according to an embodiment of the present invention;

[0035] Figure 6 It is a schematic diagram of the overall construction process of an embodiment of the present invention.

[0036] Reference numerals:

[0037] 1-anchor rod; 2-tunnel roof; 3-tunnel sides; 4-tunnel bottom plate; 5-rectangular groove; 6-fiber reinforced cement-based composite material; 7-waste gangue; 8-FRP grid; 9-positioning bolt; 10-nut. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0039] See attached Figure 1-6As shown, a bottom drum tunnel reinforcement and repair method of this embodiment includes the following steps:

[0040] Step one, after using anchor rods 1 to reinforce the tunnel roof 2 and the two sides 3 of the tunnel, a plurality of grooves are opened on the tunnel bottom plate 4 along the direction of the tunnel, and the width of the grooves is 20-40 cm and the depth is 30-50 cm. In this embodiment, three rectangular grooves 5 with a width of 20 cm and a depth of 50 cm are opened; one of the rectangular grooves 5 is located at the center of the tunnel width, and the other two rectangular grooves 5 are symmetrically arranged on both sides of the center of the tunnel width, and are 30-50 cm away from the two sides 3 of the tunnel respectively. By opening rectangular grooves 5 on the tunnel bottom plate 4, the stress concentration of the tunnel bottom plate 4 can be effectively reduced, and deformation space can be provided for stress release of the tunnel bottom plate 4;

[0041] Step 2. Although the three rectangular grooves 5 opened on the tunnel floor 4 can provide space for stress release, the tunnel floor 4 after the rectangular grooves 5 are opened is not conducive to normal transportation and pedestrians. In order to solve the above problems, it is necessary to inject fiber-reinforced cement-based composite materials 6 into the rectangular grooves 5 in sequence. The fiber-reinforced cement-based composite material 6 is composed of coal gangue aggregate, fast-hardening sulphoaluminate cement, ultra-high molecular weight polyethylene fiber and mine water. The use of fiber-reinforced cement-based composite material 6 can complete the curing reaction in a shorter time, usually within 1 day to meet the normal transportation and pedestrian needs, and realize the rapid repair of the bottom drum tunnel.

[0042] Step 3: When the tunnel floor 4 (the floor rock layer outside the rectangular groove) has a bottom bulge and the maximum bulge height exceeds 10 cm, a pneumatic rock drill is used to "excavate the bottom". The "excavation" depth is 50 cm. The waste waste rock 7 generated during the "excavation" process is temporarily accumulated within 5 meters of the "excavation" position;

[0043] Step 4, lay the FRP mesh 8 horizontally on the tunnel floor 4 after the "bottoming out", and fix it to the tunnel floor 4 by positioning bolts 9 and nuts 10. The FRP mesh 8 is a honeycomb three-dimensional structure produced by an extrusion molding process, and its matrix material includes but is not limited to basalt fiber, glass fiber and carbon fiber. The length of the FRP mesh 8 is the actual width of the tunnel floor 4, and the width of the FRP mesh 8 is half of its length. The positioning bolts 9 are full-length tapped screws, and the length of the full-length tapping is 40 cm. After the FRP mesh 8 is laid flat, drill holes in the pores of the FRP mesh, and the positioning bolts 9 are anchored to the tunnel floor 4 by resin rolls, and the drilling depth is 10 cm. Subsequently, the nuts 10 are passed through the FRP mesh 8 and tightened to achieve the purpose of fixing the FRP mesh 8.

[0044] Step 5: Lay the waste gangue 7 on the upper part of the FRP grid 8 fixed to the tunnel floor 4 by positioning bolts 9 and nuts 10, and the designed laying thickness is 20 cm. Considering the heterogeneity of the waste gangue 9, the designed laying thickness is the maximum height of the piled waste gangue 9 from the tunnel floor 4. To ensure that the laid waste gangue 7 on the tunnel floor 4 is relatively stable, the surface is manually leveled with a shovel after the filling is completed.

[0045] Step 6: A second layer of FRP mesh 8 is set up on the first layer of waste rock 7, and the second layer of FRP mesh 8 is fixed together with the positioning bolts 9 through nuts 10. The second layer of FRP mesh 8 and the first layer of FRP mesh 8 laid on the roadway floor 4 are arranged parallel in space.

[0046] Step 7: laying waste rock 7 on the upper part of the second layer of FRP grid 8, with a designed laying thickness of 20 cm. The designed laying thickness is the maximum distance between the piled waste rock 7 and the upper edge of the second layer of FRP grid 8. To ensure that the laid waste rock 7 is relatively stable, the surface is manually leveled with a shovel after the filling is completed.

[0047] Step eight, laying a third layer of FRP mesh 8 on the waste gangue 7. The third layer of FRP mesh 8 is arranged parallel to the second layer of FRP mesh 8 in space, and is fixed on the positioning bolts 9 by nuts 10.

[0048] Step nine, inject the fiber reinforced cement-based composite material 6 using coal gangue as aggregate onto the waste gangue 7 laid in the middle of the FRP grid 8 until all the gaps are filled. To ensure that the fiber reinforced cement-based composite material 6 can completely fill the gaps in the waste gangue 7, the pressure of the grouting pump used to transport the fiber reinforced cement-based composite material 6 shall not be less than 2 MPa.

[0049] Step 10: Repeat steps 4 to 9 until all filling work is completed.

[0050] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for repairing a bottom drum roadway using FRP mesh fiber reinforced cement-based composite materials, comprising the following steps: Step 1: Open multiple grooves on the bottom plate of the tunnel along the direction of the tunnel; Step 2, injecting fiber-reinforced cement-based composite materials into the multiple grooves in sequence; Step 3: When the bottom bulge appears in the bottom rock layer outside the rectangular groove and the maximum bulge height exceeds 10 cm, a pneumatic rock drill is used to "dig up the bottom"; Step 4: Lay the FRP grid horizontally on the tunnel floor after "bottoming out" and fix it to the tunnel floor with positioning bolts and nuts; Step 5: laying the waste gangue produced by "bottoming out" in step 3 on the upper part of the FRP grid fixed on the bottom plate of the roadway; Step 6: Install a second layer of FRP grid on the first layer of waste rock and fix it with nuts and positioning bolts; Step 7, laying waste gangue on the upper part of the second layer of FRP grid; Step 8: Lay the third layer of FRP mesh on the waste rock and fix it on the positioning bolts through nuts; Step nine, injecting the fiber reinforced cement-based composite material using coal gangue as aggregate onto the waste gangue laid in the middle of the FRP grid until all the gaps are filled; Step 10: Repeat steps 4 to 9 until all filling work is completed.

2. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The width of the groove is 20-40 cm and the depth is 50 cm. One of the grooves is located at the center of the lane width, and the other two rectangular grooves are symmetrically arranged on both sides of the center of the lane width, 30-50 cm away from both sides of the lane respectively.

3. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The aggregate used in the fiber-reinforced cement-based composite material is coal gangue.

4. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The cementitious material of the fiber-reinforced cement-based composite material is fast-hardening sulphoaluminate cement.

5. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The fiber material of the fiber-reinforced cement-based composite material is ultra-high molecular weight polyethylene fiber.

6. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The water used in the fiber-reinforced cement-based composite material is mine water that has been purified underground.

7. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The FRP grid is a honeycomb three-dimensional structure produced by an extrusion molding process.

8. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The matrix material of the FRP grid is any one of basalt fiber, glass fiber and carbon fiber.

9. The method for repairing a floor drum roadway using a FRP mesh fiber reinforced cement-based composite material according to claim 1, characterized in that: The length of the FRP mesh is the actual width of the tunnel floor, and the width of the FRP mesh is half of its length.

10. The method for repairing a floor drum roadway using FRP mesh fiber reinforced cement-based composite materials according to claim 1, characterized in that: The fiber-reinforced cement-based composite material completely fills the gaps in the waste gangue, and the pressure of the grouting pump used to transport the fiber-reinforced cement-based composite material shall not be less than 2 MPa.

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