Method for pre-reinforcing shallow buried section of tunnel

Abstract

The invention discloses a method for pre-reinforcing a shallow buried section of a tunnel, which comprises the following steps of: S1, fixing a point: determining the position of an anchoring point of a to-be-reinforced section of the tunnel, and marking; s2, punching is conducted, specifically, anchor rod holes are vertically and downwards punched in the positions of the anchoring points through a punching mechanism; s3, rod placing, wherein at least one vertical anchor rod is placed in the anchor rod hole; s4, grouting is conducted, specifically, mortar is injected into the anchor rod hole under pressure through a grouting mechanism; and S5, reinforcement is conducted, specifically, after grouting is completed, concrete is poured on the top of the tunnel, and all the vertical anchor rods are connected into a whole. The device is simple in structure, and through reinforcement of the anchor rods, when the top of a tunnel is subjected to pressure of surrounding rock above, vertical supporting force provided by the vertical anchor rods can share the weight of the surrounding rock above, the pressure borne by a tunnel vault is reduced, and the sinking trend of the vault is effectively resisted.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel reinforcement, and in particular to a method for pre-reinforcing a shallow buried section of a tunnel. Background Art

[0002] With the rapid development of transportation infrastructure construction, a large number of tunnel projects have emerged. Shallow buried tunnels refer to tunnels with a thinner cover layer on the top, generally less than 8 meters. Shallow buried tunnel construction is prone to roof falls. Once a roof fall occurs during tunnel excavation, a large amount of surrounding rock may suddenly collapse into the tunnel excavation surface, causing serious casualties and property losses. In addition, roof fall accidents may further cause surface subsidence and affect the safety and stability of the surrounding environment. Effective technology to prevent excavation roof falls is imminent, which is of vital importance to ensuring tunnel construction safety, improving project quality and protecting the surrounding environment.

[0003] For example, the patent with publication number CN218542269U discloses a tunnel support structure for layered surrounding rock tunnels that resist shear and release energy; the support structure includes a plurality of prestressed anchor rods arranged around the outside of the tunnel, and a plurality of energy release mechanisms arranged along the radial direction of the tunnel, wherein the prestressed anchor rods are arranged along the radial direction of the tunnel, the prestressed anchor rods are extended toward the inside of the surrounding rock, and the energy release mechanism is connected to the initial support steel frame of the tunnel.

[0004] However, the device still has the following problems:

[0005] 1. The use of radial anchors to reinforce the top of the tunnel can only be done after excavation. The tunnel must be dug out first, and then the top of the tunnel must be anchored. This cannot provide safety during excavation.

[0006] 2. During the construction of underground tunnels, in small-section tunnels or narrow lanes, the operating space for reinforcing the arch range at the top of the tunnel is limited, and the anchor drilling accuracy is poor, which affects the subsequent reinforcement effect.

[0007] 3. After grouting in the anchor hole, the mortar deep in the anchor hole is prone to produce bubbles or gaps, affecting the subsequent reinforcement capacity. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, a method for pre-reinforcement of a shallow buried section of a tunnel is provided.

[0009] The technical solution adopted by the present invention to solve its technical problem is:

[0010] The present invention proposes a method for pre-reinforcement of a shallow buried section of a tunnel, comprising the following steps:

[0011] S1: Locating points: determine the anchor point locations of the tunnel sections to be reinforced and mark them;

[0012] S2: Drilling: At the anchor point, use the drilling mechanism to drill the anchor hole vertically downward;

[0013] S3: Putting the anchor rod: Put at least one vertical anchor rod into the anchor rod hole;

[0014] S4: Grouting: inject mortar under pressure into the anchor hole through the grouting mechanism;

[0015] S5: Reinforcement: After grouting, concrete is poured on the top of the tunnel to connect all vertical anchors to form a whole.

[0016] Preferably, in S1, marking is performed by spraying or pre-punching.

[0017] Preferably, in S2, the diameter of the hole is 100 mm, the angle range of the hole is 140° in the tunnel arch, the width range of the hole is 1 m outside the tunnel excavation contour line, the hole depth is 1 m inside the tunnel excavation contour line, and the hole spacing is a plum blossom arrangement of 1.0 m×1.0 m.

[0018] Preferably, in S4, M35 cement mortar is used for grouting in the anchor hole, and the grouting pressure is not less than 0.4 MPa.

[0019] Preferably, the grouting mechanism comprises a grouting pipe and a grouting tank, a grouting pump is arranged in the grouting tank, the upper end of the grouting pipe is connected to the grouting tank, and a vibration component is arranged on one side of the grouting pipe.

[0020] Preferably, the vibration assembly includes a vibration rod, a vibration motor is arranged inside the vibration rod, a float is slidably arranged on the upper end of the vibration rod, a switch is also fixed on the upper end of the vibration rod, and the float cooperates with the switch.

[0021] Preferably, a plurality of fixing rings are fixed on one side of the vibration rod, and the fixing rings are sleeved on the outer wall of the grouting pipe. A limiting rod for limiting the relative sliding of the grouting pipe and the vibration rod is arranged inside the vibration rod. A pressure rod is also slid inside the vibration rod, and one end of the pressure rod is connected to the limiting rod, and the other end cooperates with the float.

[0022] Preferably, a flap which can rotate to change the inner diameter of the grouting pipe is provided at the lower end of the grouting pipe, and a push rod is also slidably provided at the lower end of the grouting pipe, and the push rod is fixed to the grouting pipe by a spring; one end of the push rod is in contact with the flap, and the other end is provided with a limit groove which cooperates with the limit rod.

[0023] Preferably, an insertion rod for limiting the left and right sliding of the push rod is arranged in the grouting pipe, and a slot is opened on one side of the push rod, and the slot cooperates with the insertion rod.

[0024] Preferably, a lifting groove is provided on one side of the vibration rod, and a lifting rod matching the lifting groove is provided in the grouting pipe.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts vertical anchor rods for reinforcement within a certain range of the tunnel top, provides support and protection for the tunnel top before excavation, can apply prestress before the surrounding rock is deformed, actively restrain the deformation of the surrounding rock, provide effective protection during tunnel excavation, and reduce the construction in the tunnel; at the same time, the vertical anchor rods are reinforced, so that when the tunnel top is subjected to the pressure of the surrounding rock above, the vertical supporting force provided by the vertical anchor rods can share the weight of the upper surrounding rock, reduce the pressure on the tunnel arch, and effectively resist the sinking trend of the arch.

[0027] 2. The present invention uses drilling from the top of the tunnel to insert anchor rods before excavation. The construction is not limited by space and has high construction accuracy. At the same time, it can be flexibly adjusted according to different geological conditions. By changing the position and density of anchor rod reinforcement, it can adapt to complex and changeable construction conditions. After digging the tunnel, radial anchor rods are used at the bottom for further reinforcement, which further improves the bearing capacity of the tunnel.

[0028] 3. The grouting mechanism used in the present invention can inject grout into the anchor hole under pressure, ensuring that the mortar can diffuse to the surroundings through the hole wall, pre-reinforce the surrounding rock, and further enhance the firmness of the surrounding rock.

[0029] 4. The vibration component adopted in the present invention can detect whether the mortar in the anchor hole is full. When it is full, the limit rod will release the limit on the grouting pipe, and the vibration motor will be turned on at the same time. The vibration component vibrates the mortar from the bottom layer to make the mortar evenly distributed, reduce the stress concentration phenomenon, and greatly reduce the gap between the mortar and the anchor and the surrounding rock layer; after the grouting pipe is pulled up for a distance, it is re-connected with the vibration component to avoid affecting the vibration effect at the same height as the vibration component. After re-connection, the inner diameter of the grouting pipe outlet becomes smaller, and the slurry starts to be discharged slowly, while driving the vibration component to rise slowly, and the grouting is slowly replenished while vibrating and compacting. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0031] Figure 1 It is a schematic diagram of the anchor reinforcement range of the present invention;

[0032] Figure 2 It is a front view of the grouting mechanism of the present invention;

[0033] Figure 31 is a cross-sectional view of the grouting mechanism of the present invention (working state 1);

[0034] Figure 4 1 is a cross-sectional view of the grouting mechanism of the present invention (working state 2);

[0035] Figure 5 1 is a cross-sectional view of the grouting mechanism of the present invention (working state three);

[0036] Figure 6 It is a schematic diagram of the anchor distribution at the top of the tunnel of the present invention;

[0037] Figure 7 It is a schematic diagram of the single deformation of the tunnel after the anchor rod reinforcement of the present invention;

[0038] Figure 8 It is a schematic diagram of the cumulative deformation of the tunnel after the anchor reinforcement of the present invention (short time);

[0039] Fig. 9 It is a schematic diagram of the cumulative deformation of the tunnel after anchor reinforcement according to the present invention (long time).

[0040] Description of reference numerals:

[0041] 1. Tunnel; 2. Contour line; 3. Vertical anchor rod; 4. Grouting pipe; 5. Vibration rod; 6. Vibration motor; 7. Float; 8. Switch; 9. Fixed ring; 10. Limit rod; 11. Pressure rod; 12. Flap; 13. Push rod; 14. Spring; 15. Limit groove; 16. Slot; 17. Insert rod; 18. Lifting groove; 19. Lifting rod; 20. Compression spring; 21. First connecting rod; 22. Second connecting rod; 23. Third connecting rod; 24. Mortar anchor rod. DETAILED DESCRIPTION

[0042] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0043] Reference Figure 1 -Attached Fig. 9 This embodiment proposes a method for pre-reinforcement of a shallow buried section of a tunnel, comprising the following steps:

[0044] S1: Point determination: According to the direction of tunnel 1 and the design range of tunnel contour line 2, the anchor point position of the section to be reinforced of tunnel 1 is determined and marked;

[0045] S2: Drilling: At the anchor point, use the drilling mechanism to drill the anchor hole vertically downward;

[0046] S3: placing the anchor: placing at least one vertical anchor 3 into the anchor hole;

[0047] S4: Grouting: inject mortar under pressure into the anchor hole through the grouting mechanism;

[0048] S5: Reinforcement: After the grouting is completed, concrete is poured on the top of the tunnel to connect the top ends of all vertical anchor rods 3 to form a whole.

[0049] The tunnel contour line 2 is a boundary line designed in advance before the tunnel 1 is excavated and is used to define the final excavation shape of the tunnel.

[0050] In S1, marking is performed by spraying or pre-punching.

[0051] Spraying uses paint or pigment to mark the anchor points.

[0052] Since the drilling machinery for anchor holes is relatively heavy, pre-drilling is done at the anchor point using a small, portable drilling device to pre-drill shallow holes to facilitate the positioning of the anchor holes later.

[0053] In S2, the drilling machine adopts a common hydraulic anchor drilling rig or an electric anchor drilling rig. The hydraulic anchor drilling rig uses a hydraulic system to provide power. The hydraulic pump pressurizes the hydraulic oil and transmits it to the hydraulic motor and thrust cylinder of the drilling rig. The hydraulic motor drives the drill rod to rotate, and the thrust cylinder pushes the drill rod forward to drill. The electric anchor drilling rig is powered by an electric motor. The motor drives the drill rod to rotate, and then the electric push rod is pushed forward to drill.

[0054] In S2, the diameter of the hole is 100 mm, and the angle range of the hole is 135-145° in the tunnel arch, preferably 140°; outside 140°, after the tunnel is excavated, conventional mortar anchor rods 24 are used for radial support, and the width range of the hole is 0.5-2m outside the tunnel excavation contour line 2, preferably 1m, and the hole depth is 0.5-2m inside the tunnel excavation contour line 2, preferably 1m, and the hole spacing is 1.0m×1.0m plum blossom arrangement.

[0055] The vertical anchor rod 3 adopts φ25 glass fiber anchor rod, and the mortar anchor rod 24 adopts φ22 steel bar.

[0056] In S2, vertical anchor reinforcement is used before tunnel excavation, which can pre-reinforce the surrounding rock at the top of the tunnel before tunnel excavation, and directly provide safety protection when the tunnel is excavated in the later stage. The commonly used radial anchor reinforcement on the top of the tunnel requires drilling and placing anchor reinforcement after tunnel excavation, which cannot provide safety protection when the tunnel is excavated.

[0057] Radial anchor reinforcement is to drive anchors into the surrounding rock along the circumferential direction of the tunnel. The direction and angle of the drilling must be precisely controlled. After the tunnel is excavated, it is difficult to drill holes on the top of the tunnel. Once the drilling angle deviation is too large, the anchors will not be able to effectively reinforce the surrounding rock and may even affect the reinforcement effect of adjacent anchors. The vertical anchor reinforcement on the top of the tunnel is to measure the top of the tunnel in advance, then mark or pre-drill holes, and finally drill vertically downwards uniformly. It can be flexibly adjusted according to different geological conditions, and has better reinforcement effect and adaptability.

[0058] The top of the tunnel is reinforced with radial anchor rods. In small tunnels or narrow spaces, the construction space is limited, which can easily affect the construction effect. Vertical reinforcement is carried out at the top of the tunnel, and there is no problem of limited construction methods.

[0059] After the top of the tunnel is reinforced with vertical anchor rods 3, radial mortar anchor rods 24 are used at the bottom for reinforcement, so that the tunnel can be further reinforced in a relatively safe situation. At the same time, the radial anchor rod holes at the bottom are relatively convenient to operate.

[0060] In S4, M35 cement mortar is used to grout the anchor hole with a grouting pressure of no less than 0.4 MPa to ensure that the grouting can diffuse through the hole wall to the surrounding area and pre-reinforce the surrounding rock.

[0061] The grouting mechanism comprises a grouting pipe 4 and a grouting tank. A grouting pump is arranged in the grouting tank. The upper end of the grouting pipe 4 is connected to the grouting tank. A vibration component is arranged on one side of the grouting pipe 4.

[0062] After placing the vertical anchor rod 3 into the drilled anchor hole, place the grouting pipe 4 into the bottom of the anchor hole, start the grouting pump, and the grouting pump pressurizes the cement mortar in the grouting tank through the grouting pipe 4 and injects it into the bottom of the anchor hole, so that the cement mortar overflows upward from the bottom of the anchor hole.

[0063] The vibration assembly includes a vibration rod 5, in which a vibration motor 6 is arranged, a float 7 is slidably arranged on the upper end of the vibration rod 5, a limit block is fixed on the vibration rod to prevent the float 7 from sliding down, and a switch 8 is also fixed on the upper end of the vibration rod 5, and the float 7 cooperates with the switch 8.

[0064] When the cement mortar overflows from the anchor hole, it will drive the float 7 to slide upward, and the float 7 touches the switch 8, and the switch 8 is electrically connected to the vibration motor 6. After the switch 8 is touched and energized, the vibration motor 6 starts to energize and work, vibrating and compacting the cement mortar at the bottom.

[0065] A plurality of fixing rings 9 are fixed on one side of the vibration rod 5, and the fixing ring 9 is sleeved on the outer wall of the grouting pipe 4. A limiting rod 10 is arranged inside the vibration rod 5 to limit the relative sliding of the grouting pipe 4 and the vibration rod 5. The limiting rod 10 is connected to the vibration rod 5 in a horizontal sliding direction. A pressure rod 11 is also slidably arranged inside the vibration rod 5, and one end of the pressure rod 11 is connected to the limiting rod 10, and the other end cooperates with the float 7.

[0066] The pressure rod 11 is connected to the vibration rod 5 in a sliding manner in the horizontal direction. There is also a second connecting rod 22 that slides vertically in the vertical direction inside the vibration rod 5. The second connecting rod 22 and the vibration rod 5 are fixed by a compression spring 20. A first connecting rod 21 and a third connecting rod 23 are also provided in the vibration rod 5. The upper ends of the pressure rod 11 and the second connecting rod 22 are hinged by the first connecting rod 21, and the lower ends of the limit rod 10 and the second connecting rod 22 are hinged by the third connecting rod 23.

[0067] When the cement mortar does not overflow from the anchor hole, the float 7 is at the upper end of the limit block, and the inner wall of the float 7 limits the pressure rod 11 in the vibration rod 5. The pressure rod drives the second connecting rod 22 to slide downward through the first connecting rod 21, and the compression spring 20 is compressed. At the same time, the limit rod 10 limits the relative sliding of the grouting pipe 4 and the vibration rod 5. At this time, the grouting pipe 4 and the vibration rod 5 rise and fall together; after the cement mortar overflows from the anchor hole, the float 7 slides upward and no longer limits the displacement of the pressure rod 11. The compression spring 20 extends, pushing the second connecting rod 22 to slide upward, and the pressure rod 11 extends out of the upper end of the vibration rod 5.

[0068] The lower end of the grouting pipe 4 is rotatably connected to a flap 12 which can change the inner diameter of the grouting pipe 4. The lower end of the grouting pipe 4 is also slidably connected to a push rod 13, which is fixed to the grouting pipe 4 by a spring 14. One end of the push rod 13 is in contact with the flap 12, and the other end is provided with a limit groove 15 which cooperates with the limit rod 10.

[0069] When the limiting rod 10 is inserted into the limiting groove 15 on the top rod 13, the limiting groove 15 is horizontal, and the limiting rod 10 can limit the relative sliding of the grouting pipe 4 and the vibration rod 5 at this time; when the second connecting rod 22 slides upward, it is driven by the third connecting rod 23 to slide the limiting rod 10 out of the limiting groove 15, thereby releasing the restriction between the grouting pipe 4 and the vibration rod 5, so that the grouting pipe 4 and the vibration rod 5 can slide relative to each other again.

[0070] There is a slide groove on one side of the vibration rod 5, and the slide groove has a vertical surface and an inclined surface. When the limit rod 10 is inserted into the limit groove 15, under the action of the spring 14, the push rod 13 is at the bottom of the inclined surface. After the limit is released, due to the limitation of the fixing ring 9, only vertical displacement can occur between the grouting pipe 4 and the vibration rod 5, and horizontal displacement cannot be performed. The grouting pipe 4 is pulled upward, and the vibration rod 5 remains stationary. At this time, the push rod 13 slides upward on the inclined surface, and the spring 14 is continuously compressed. The push rod 13 gradually slides into the grouting pipe 4, and at the same time drives the flap 12 to rotate, changing the inner diameter of the outlet position of the grouting pipe 4, so that the slurry discharge per unit time is reduced, and it is avoided that after the top mortar overflows, a large flow of grouting is still carried out, causing waste.

[0071] An insertion rod 17 is provided in the grouting pipe 4 to limit the left and right sliding of the push rod 13. The insertion rod 17 is fixedly connected to the grouting pipe 4 through an elastic component. The elastic component can be a common elastic element such as a spring or elastic rubber. A slot 16 is provided on one side of the push rod 13, and the slot 16 cooperates with the insertion rod 17.

[0072] The top rod 13 moves along the slide groove on the vibration rod 5. When it moves to the vertical surface of the slide groove, the slot 16 on the top rod moves to the position of the insertion rod 17. Under the action of the elastic component, the insertion rod 17 is inserted into the slide groove 16 to limit the left and right sliding of the top rod 13, so that the flap 12 cannot be reversed, and the grouting pipe 4 continues to be in a small flow state.

[0073] A lifting groove 18 is provided on one side of the vibration rod 5, and a lifting rod 19 matching the lifting groove 18 is provided in the grouting pipe 4. The lifting rod 19 is fixed to the grouting pipe 4 through an elastic component, and the elastic component can adopt common elastic elements such as springs or elastic rubber.

[0074] As the grouting pipe 4 is continuously pulled upward, the lifting rod 19 moves upward along with the grouting pipe 4. When the lifting rod 19 moves to the position of the lifting groove 18, under the action of the elastic force of the elastic component, the lifting rod 19 is inserted into the lifting groove 18, so that the relative sliding between the grouting pipe 4 and the vibration rod 5 is restricted again. At this time, the position of the vibration motor 6 is lower than the lower surface of the grouting pipe 4, avoiding the grouting pipe 4 and the vibration component being at the same height to affect the vibration effect.

[0075] When the grouting pipe 4 is pulled upward, the vibration assembly is driven up together, so that the vibration motor 6 can vibrate and compact the mortar at the bottom. After vibration and compaction, intermittent or cavities will appear inside the mortar, so the grouting pipe 4 discharges the mortar at a small flow rate above the vibration motor 6, which can be replenished in time until the grouting pipe 4 drives the vibration tube 5 to reach the top of the anchor hole to complete the grouting work.

[0076] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for pre-reinforcement of shallow buried tunnel section, characterized in that: The following steps are involved: S1: Locating points: Determine the anchor point locations of the tunnel (1) section to be reinforced and mark them; S2: Drilling: At the anchor point, use the drilling mechanism to drill the anchor hole vertically downward; S3: placing the anchor: placing at least one vertical anchor (3) into the anchor hole; S4: Grouting: inject mortar under pressure into the anchor hole through the grouting mechanism; S5: Reinforcement: After the grouting is completed, concrete is poured on the top of the tunnel to connect all the vertical anchors (3) to form a whole.

2. The method for pre-reinforcement of shallow buried tunnel section according to claim 1, characterized in that: In S1, marking is performed by spraying or pre-punching.

3. The method for pre-reinforcement of shallow buried tunnel section according to claim 1, characterized in that: In S2, the diameter of the hole is 100 mm, the angle range of the hole is 140° in the tunnel arch, the width range of the hole is 1 m outside the tunnel excavation contour line (2), the hole depth is 1 m inside the tunnel excavation contour line (2), and the hole spacing is a plum blossom arrangement of 1.0 m × 1.0 m.

4. The method for pre-reinforcement of shallow buried tunnel section according to claim 1, characterized in that: In S4, M35 cement mortar is used to grout the anchor hole, and the grouting pressure is not less than 0.4MPa.

5. The method for pre-reinforcement of shallow buried tunnel section according to claim 1, characterized in that: The grouting mechanism comprises a grouting pipe (4) and a grouting tank, a grouting pump is arranged in the grouting tank, the upper end of the grouting pipe (4) is connected to the grouting tank, and a vibration component is arranged on one side of the grouting pipe (4).

6. The method for pre-reinforcement of shallow buried tunnel section according to claim 5, characterized in that: The vibration assembly comprises a vibration rod (5), a vibration motor (6) is arranged inside the vibration rod (5), a float (7) is slidably mounted on the upper end of the vibration rod (5), a switch (8) is also fixed on the upper end of the vibration rod (5), and the float (7) cooperates with the switch (8).

7. The method for pre-reinforcement of shallow buried tunnel section according to claim 6, characterized in that: A plurality of fixing rings (9) are fixed on one side of the vibration rod (5), and the fixing ring (9) is sleeved on the outer wall of the grouting pipe (4). A limiting rod (10) is arranged inside the vibration rod (5) to limit the relative sliding of the grouting pipe (4) and the vibration rod (5). A pressure rod (11) is also slidable inside the vibration rod (5), and one end of the pressure rod (11) is connected to the limiting rod (10), and the other end cooperates with the float (7).

8. The method for pre-reinforcement of shallow buried tunnel section according to claim 7, characterized in that: The lower end of the grouting pipe (4) is provided with a rotatable flap (12) capable of changing the inner diameter of the grouting pipe (4), and the lower end of the grouting pipe (4) is also provided with a sliding push rod (13), the push rod (13) and the grouting pipe (4) being fixed by a spring (14); one end of the push rod (13) is in contact with the flap (12), and the other end is provided with a limiting groove (15) matching with the limiting rod (10).

9. The method for pre-reinforcement of shallow buried tunnel section according to claim 8, characterized in that: The grouting pipe (4) is provided with an insertion rod (17) for limiting the left and right sliding of the push rod (13); a slot (16) is provided on one side of the push rod (13); the slot (16) matches the insertion rod (17).

10. The method for pre-reinforcement of shallow buried tunnel section according to claim 9, characterized in that: A lifting groove (18) is provided on one side of the vibration rod (5), and a lifting rod (19) matching with the lifting groove (18) is provided in the grouting pipe (4).

Images