Anti-deformation shield tunnel construction method for underneath passing existing tunnel at small clear distance

Abstract

The invention relates to the technical field of shield methods, in particular to an anti-deformation shield tunnel construction method for underneath passing an existing tunnel at a small clear distance, a soil body between a preceding tunnel and a following tunnel is reinforced by mixing piles, the reinforcing width is 3-5 m on each of the two sides of the outer diameter of the tunnel, the reinforcing depth needs to exceed the bottom of the tunnel by 2-3 m, the diameter of the mixing piles is 0.6-1.0 m, the pile distance is 0.8-1.2 m, and the cement mixing amount is 15-20%; the diameter of the jet grouting piles is 0.8-1.2 m, the grouting pressure is 20-30 MPa, the water-cement ratio of grout is 1: 1, reinforced concrete isolation piles with the diameter of 0.8-1.2 m are adopted, the pile distance is 1.0-1.5 m, the embedded bedrock is larger than or equal to 2 m, and a reinforcing structure is arranged in the tunnel. The device has the advantages of soil body reinforcement and reinforcement, accurate grouting reinforcement, stable support, fine tunneling control and real-time monitoring and early warning. According to the method, the soil body between the preceding tunnel and the following tunnel is reinforced through the stirring piles and the jet grouting piles, the strength and stability of the soil body are effectively improved, the risks of ground surface settlement and tunnel deformation in the shield tunneling process are reduced, and meanwhile the reinforcing effect is further enhanced by embedding the reinforced concrete isolation piles.

Description

Technical Field

[0001] The present invention relates to the technical field of shield tunneling method, and specifically to a construction method for a deformation-preventing shield tunnel with a small clear distance passing under an existing tunnel. Background Technique

[0002] The shield tunneling method refers to a construction method that uses a special shield machine with a shield to carry out operations such as tunnel excavation and lining in soft foundations or broken rock formations. During the propulsion process of the shield machine, the pre-installed lining blocks at the tail are used as fulcrums to move forward, the cutter head cuts the soil, and at the same time, the soil is discharged and the precast concrete lining blocks behind are assembled. In this way, the tunneling and support of the tunnel can be carried out synchronously.

[0003] During the construction process of shield tunnels, in terms of reinforcement, only a single reinforcement measure is adopted, such as only using mixing piles or grouting reinforcement, resulting in an unsatisfactory reinforcement effect and difficulty in effectively resisting surface settlement and tunnel deformation during shield tunneling; and during construction, there is a lack of an effective dynamic support system, resulting in the tunnel structure being easily disturbed and deformed during shield tunneling, thus increasing construction risks and potential safety hazards; further, the settings of key parameters such as the tunneling process, speed, and cutter head torque of some shield machines are not reasonable enough, resulting in low tunneling efficiency and an increased risk of surface settlement and tunnel deformation; finally, the existing technology may lack a comprehensive monitoring and early warning system, making it difficult to detect and handle potential safety hazards during tunnel construction in a timely manner, which may lead to the occurrence of safety accidents and a decline in project quality.

[0004] Therefore, there is an urgent need for a construction method for a deformation-preventing shield tunnel with a small clear distance passing under an existing tunnel to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method for a deformation-preventing shield tunnel with a small clear distance passing under an existing tunnel, which has the advantages of strengthened soil reinforcement, precise grouting reinforcement, stable support, fine tunneling control, and real-time monitoring and early warning, and solves the problems raised in the above background technique.

[0006] To achieve the above object, the present invention provides the following technical solution: A construction method for a deformation-preventing shield tunnel with a small clear distance passing under an existing tunnel, the method comprising the following steps:

[0007] S1: The soil between the advanced tunnel and the subsequent tunnel is reinforced with mixing piles. The reinforcement width is 3 - 5 m on each side of the outer diameter of the tunnel, and the depth needs to exceed the bottom of the tunnel by 2 - 3 m. The mixing pile diameter is 0.6 - 1.0 m, the pile spacing is 0.8 - 1.2 m, and the cement content is 15% - 20%. The jet grouting pile diameter is 0.8 - 1.2 m, the grouting pressure is 20 - 30 MPa, the water-cement ratio of the slurry is 1:1. Reinforced concrete isolation piles with a diameter of 0.8 - 1.2 m are used, the pile spacing is 1.0 - 1.5 m, and the embedding depth into the bedrock is ≥2 m. And a reinforcement structure is set in the tunnel.

[0008] S2: After the excavation of the advanced tunnel is completed, immediately grout and reinforce the length of 30 - 50 m in the small clear distance range of the subsequent tunnel; the grouting pressure is 1.0 - 2.0 MPa, the slurry uses cement-sodium silicate double-fluid slurry, the diffusion radius is 0.8 - 1.2 m, and the single-hole grouting volume is ≥1.5 m 3 。

[0009] S3: Install a traveling hydraulic support trolley in the advanced tunnel. The support spacing is 3 - 5 ring segments, and the width of each ring is 1.2 - 1.5 m. When the shield of the subsequent tunnel advances to the small clear distance range, the trolley moves at a step distance of 5 - 10 m / step.

[0010] S4: Control according to 1.1 - 1.3 times the static earth pressure, reduce the propulsion speed to 10 - 20 mm / min, control the cutter head torque at 60% - 70% of the rated value, the grouting pressure is 0.3 - 0.5 MPa, the initial setting time is ≤6 h, inject foaming agent, and the foaming ratio is 10 - 15 times to ensure the slump of the muck is 150 - 180 mm.

[0011] S5: The monitoring point spacing is 5 m, and the alarm value is cumulative ±15 mm and the change rate is 2 mm / d. Install an automatic total station to monitor the horizontal convergence and vertical displacement. The alarm value of the former is ±10 mm, and the alarm value of the latter is ±8 mm. The monitoring point spacing is 10 m.

[0012] Further, as a preferred embodiment of the present invention, in the step S2, the volume ratio of the cement-sodium silicate double-fluid slurry is 1:0.6.

[0013] Further, as a preferred embodiment of the present invention, data collection is carried out once every 1.2 - 1.5 m of excavation for 1 ring.

[0014] Furthermore, as a preferred reinforcement structure of the present invention, the reinforcement structure is arranged in a shield tunnel. The reinforcement structure includes a reinforcement frame. Two mounting plates are fixedly connected to the bottom of the reinforcement frame. A fixing plate is arranged on the inner wall of the reinforcement frame. Bottom plates are fixedly connected to both sides of the fixing plate. Two first fixing bolts penetrate through one side of the bottom plate. A chute is formed on the surface of the reinforcement frame. A number of sliders are slidably connected in the inner cavity of the chute. One side of the slider is fixedly connected to the fixing plate.

[0015] Furthermore, as a preferred embodiment of the present invention, two second fixing bolts penetrate through the top of the mounting plate, and the number of the second fixing bolts is four.

[0016] Furthermore, as a preferred embodiment of the present invention, anti-slip patterns are provided on the surface of the reinforcement frame.

[0017] Furthermore, as a preferred embodiment of the present invention, limiting grooves are formed on both sides of the inner cavity of the chute. The limiting blocks are slidably connected to the inner cavities of the limiting grooves and the chute together. One side of the limiting block is fixedly connected to the slider.

[0018] In the present invention, the implementation steps of the reinforcement structure are as follows:

[0019] Step 1: When using the reinforcement structure, place the reinforcement frame in the shield tunnel. The second fixing bolts tightly connect the mounting plate to the tunnel, providing initial support for the reinforcement frame and ensuring the stability of subsequent adjustments. Slide the slider in the inner cavity of the chute to adjust the relative position between the fixing plate and the reinforcement frame. During this process, continuous observation and adjustment are required to find the best fixing points while ensuring the stability and accuracy during the installation process.

[0020] Step 2: As the fixing plate moves, the bottom plate will move in the same direction. When the fixing plate moves to the predetermined position, the two first fixing bolts penetrating through one side of the bottom plate are used to achieve the stable connection between the tunnel and the reinforcement frame. Since the number of the fixing plates and the bottom plates is several, the overall stability of the reinforcement frame is enhanced. To ensure the safety of the reinforcement frame in the tunnel, the slider will drive the limiting block to slide in the inner cavity of the limiting groove when moving, effectively avoiding the risk of the bottom plate and the fixing plate falling in case of an accident. To increase the friction between the tunnel and the reinforcement frame, anti-slip patterns are provided, which not only enhance the stability of the reinforcement frame but also reduce the possibility of sliding under extreme conditions.

[0021] Beneficial effects: The technical solution of this application has the following technical effects: The present invention has the advantages of strengthening soil reinforcement, precise grouting reinforcement, stable support, fine tunneling control, and real-time monitoring and early warning.

[0022] First, the method effectively improves the strength and stability of the soil mass by using mixing piles and jet grouting piles to reinforce the soil mass between the leading tunnel and the trailing tunnel, reduces the risk of ground settlement and tunnel deformation during the shield tunneling process. Meanwhile, the embedding of reinforced concrete isolation piles further enhances the reinforcement effect;

[0023] Next, the in-tunnel grouting reinforcement measures are carried out for the small clear distance range of the trailing tunnel. The control of grouting pressure and slurry ratio ensures the uniformity and reliability of the reinforcement effect. The use of cement-sodium silicate double-fluid slurry improves the setting speed and strength of the slurry, which helps to quickly stabilize the tunnel structure;

[0024] Furthermore, the introduction of a traveling hydraulic support trolley provides continuous and stable support force for shield tunneling, effectively reducing tunnel deformation during tunneling. The reasonable setting of the moving step distance and support spacing of the trolley ensures the effective coverage of the support force and the stability of the tunnel structure;

[0025] Finally, by controlling key parameters such as tunneling speed, cutter head torque, grouting pressure, and muck slump, the refined control of the tunneling process is realized. This not only reduces the risk of ground settlement and tunnel deformation, but also improves the tunneling efficiency and engineering quality. Measures such as arranging monitoring points and installing total station ensure the real-time monitoring and early warning of key indicators such as tunnel horizontal convergence and vertical displacement, which helps to timely discover and handle potential safety hazards and ensure the safety and stability of tunnel construction.

[0026] It should be understood that all combinations of the foregoing concepts and additional concepts described in more detail below can be regarded as part of the inventive subject matter of the present disclosure as long as such concepts do not contradict each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0028] Figure 1 is a schematic structural diagram of the present invention;

[0029] Figure 2 is a three-dimensional schematic diagram of a partial structure of the present invention.

[0030] In the figure, the meanings of the reference numerals are as follows: 1, reinforcement frame; 2, mounting plate; 3, fixing plate; 4, bottom plate; 5, fixing bolt; 6, chute; 7, slider; 8, fixing bolt; 9, anti-slip pattern; 10, limiting groove; 11, limiting block. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, detail the specific implementation manners, structures, features and their effects of the present invention as follows.

[0032] As shown in the attached Figure 1 to Figure 2 the attached figures: This embodiment provides a construction method for a deformation-preventing shield tunnel with a small clear distance passing under an existing tunnel, and the method includes the following steps:

[0033] S1: The soil between the advanced tunnel and the subsequent tunnel is reinforced by mixing piles. The reinforcement width is 3 - 5 m on both sides of the outer diameter of the tunnel, the depth needs to exceed the bottom of the tunnel by 2 - 3 m, the diameter of the mixing piles is 0.6 - 1.0 m, the pile spacing is 0.8 - 1.2 m, and the cement content is 15% - 20%; the diameter of the jet grouting piles is 0.8 - 1.2 m, the grouting pressure is 20 - 30 MPa, the water-cement ratio of the slurry is 1:1, and reinforced concrete isolation piles with a diameter of 0.8 - 1.2 m are used, the pile spacing is 1.0 - 1.5 m, and the embedment in the bedrock is ≥2 m, and a reinforcement structure is set in the tunnel.

[0034] S2: After the excavation of the advanced tunnel is completed, immediately conduct in-tunnel grouting reinforcement for the small clear distance range (length 30 - 50 m) of the subsequent tunnel; the grouting pressure is 1.0 - 2.0 MPa, the slurry uses cement-sodium silicate double-fluid slurry, the diffusion radius is 0.8 - 1.2 m, and the single-hole grouting volume is ≥1.5 m 3 .

[0035] S3: Install a traveling hydraulic support trolley in the advanced tunnel. The support spacing is 3 - 5 rings of segment width 1.2 - 1.5 m. When the shield of the subsequent tunnel advances to the small clear distance range, the trolley moves at a step distance of 5 - 10 m / time to ensure that the support force continuously covers the affected area.

[0036] S4: Control according to 1.1 - 1.3 times the static earth pressure. For example, it is set to 0.18 - 0.22 MPa in the sand layer and 0.15 - 0.18 MPa in the clay layer. The propulsion speed is reduced to 10 - 20 mm / min, the cutter head torque is controlled at 60% - 70% of the rated value, the grouting pressure is 0.3 - 0.5 MPa, the initial setting time is ≤6 h, and a foaming agent is injected with a foaming ratio of 10 - 15 times to ensure that the slump of the muck is 150 - 180 mm, reducing the cutter head torque and surface settlement.

[0037] S5: The monitoring points are arranged at a spacing of 5 m, and the alarm value is cumulative ±15 mm and the change rate is 2 mm / d. Install an automatic total station to monitor the horizontal convergence and vertical displacement. The alarm value for the former is ±10 mm, and the alarm value for the latter is ±8 mm, and the monitoring point spacing is 10 m.

[0038] Specifically, in the step S2, the volume ratio of the cement-sodium silicate double-fluid slurry is 1:0.6.

[0039] Specifically, in the step S4, data collection is carried out once every 1 ring (1.2 - 1.5 m) of tunneling.

[0040] Specifically, a reinforcement structure is provided in the shield tunnel. The reinforcement structure includes a reinforcement frame 1. Two mounting plates 2 are fixedly connected to the bottom of the reinforcement frame 1. A fixed plate 3 is arranged on the inner wall of the reinforcement frame 1. Two bottom plates 4 are fixedly connected to both sides of the fixed plate 3. Two first fixing bolts 5 penetrate through one side of the bottom plate 4. A chute 6 is formed on the surface of the reinforcement frame 1. A plurality of sliders 7 are slidably connected in the inner cavity of the chute 6. One side of the slider 7 is fixedly connected to the fixed plate 3.

[0041] Specifically, two second fixing bolts 8 penetrate through the top of the mounting plate 2, and the number of the second fixing bolts 8 is four.

[0042] Specifically, anti-slip patterns 9 are provided on the surface of the reinforcement frame 1.

[0043] Specifically, limiting grooves 10 are formed on both sides of the inner cavity of the chute 6. The limiting grooves 10 and the inner cavity of the chute 6 jointly slidably connect a limiting block 11. One side of the limiting block 11 is fixedly connected to the slider 7.

[0044] In the present invention, the implementation steps of the reinforcement structure are as follows:

[0045] Step 1: When using the reinforcement structure, place the reinforcement frame 1 in the shield tunnel. The second fixing bolts 8 tightly connect the mounting plate 2 to the tunnel, providing preliminary support for the reinforcement frame 1 and ensuring the stability of subsequent adjustments. Operate the slider 7 to slide in the inner cavity of the chute 6 to adjust the relative position between the fixed plate 3 and the reinforcement frame 1. During the process, continuous observation and adjustment are required to find the optimal fixing point while ensuring the stability and accuracy during installation.

[0046] Step 2: As the fixed plate 3 moves, the bottom plate 4 will move in the same direction. When the fixed plate 3 moves to the predetermined position, the two first fixing bolts 5 penetrating through one side of the bottom plate 4 are used to firmly connect the tunnel and the reinforcement frame 1. Since the number of the fixed plates 3 and the bottom plates 4 is several, the overall stability of the reinforcement frame is enhanced. To ensure the safety of the reinforcement frame 1 in the tunnel, when the slider 7 moves, it will drive the limiting block 11 to slide in the inner cavity of the limiting groove 10, effectively avoiding the risk of the bottom plate 4 and the fixed plate 3 falling in case of an accident. To increase the friction between the tunnel and the reinforcement frame 1, anti-slip patterns 9 are provided, which not only enhance the stability of the reinforcement frame 1 but also reduce the possibility of sliding under extreme conditions.

[0047] The above are only the preferred embodiments of the present invention and do not impose any formal limitations on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. Construction method of deformation-preventing shield tunnel undercutting existing tunnel with small clear distance, characterized in that: The method includes the following steps: S1: The soil between the advanced tunnel and the subsequent tunnel is reinforced by mixing piles. The reinforcement width is 3 - 5 m on each side of the outer diameter of the tunnel, and the depth needs to exceed the bottom of the tunnel by 2 - 3 m. The diameter of the mixing pile is 0.6 - 1.0 m, the pile spacing is 0.8 - 1.2 m, and the cement content is 15% - 20%; the diameter of the jet grouting pile is 0.8 - 1.2 m, the grouting pressure is 20 - 30 MPa, the water-cement ratio of the slurry is 1∶1, a reinforced concrete isolation pile with a diameter of 0.8 - 1.2 m is used, the pile spacing is 1.0 - 1.5 m, and it is embedded in the bedrock by ≥2 m, and a reinforcement structure is set in the tunnel; S2: After the excavation of the leading tunnel is completed, immediately grout and reinforce the 30-50m long section within the small clear distance range of the trailing tunnel; the grouting pressure is 1.0-2.0MPa, the grout is a cement-sodium silicate double-fluid grout, the diffusion radius is 0.8-1.2m, and the grouting volume per single hole is ≥1.5m 3 ; S3: Install a traveling hydraulic support trolley in the advanced tunnel. The support spacing is 3 - 5 ring segments of the lining, and the width of each ring is 1.2 - 1.5 m. When the shield tunneling of the subsequent tunnel reaches the small clear distance range, the trolley moves at a step distance of 5 - 10 m / time; S4: Control according to 1.1 - 1.3 times the static earth pressure, reduce the propulsion speed to 10 - 20 mm / min, control the cutter head torque at 60% - 70% of the rated value, the grouting pressure is 0.3 - 0.5 MPa, the initial setting time is ≤6 h, inject foaming agent, and the foaming ratio is 10 - 15 times to ensure that the slump of the muck is 150 - 180 mm; S5: The monitoring points are arranged at a spacing of 5 m, and the alarm value is cumulative ±15 mm and the change rate is 2 mm / d. Install an automatic total station to monitor the horizontal convergence and vertical displacement. The alarm value of the former is ±10 mm, and the alarm value of the latter is ±8 mm. The monitoring point spacing is 10 m.

2. The construction method of the anti-deformation shield tunnel passing under an existing tunnel with a small clear distance according to claim 1, characterized in that: In the step S2, the volume ratio of the cement-sodium silicate double-fluid slurry used is 1∶0.

6.

3. The construction method of a shield tunnel with anti-deformation for small clear distance undercrossing an existing tunnel according to any one of claims 1, characterized in that: In the step S4, data collection is carried out every 1.2 - 1.5 m for every 1 ring of tunneling.

4. The construction method of a shield tunnel with anti-deformation for small clear distance under-crossing an existing tunnel according to claims 1-3, characterized in that: Reinforcement structure, the reinforcement structure is arranged in the shield tunnel. The reinforcement structure includes a reinforcement frame (1). Two mounting plates (2) are fixedly connected to the bottom of the reinforcement frame (1). A fixing plate (3) is arranged on the inner wall of the reinforcement frame (1). Two bottom plates (4) are fixedly connected to both sides of the fixing plate (3). Two first fixing bolts (5) are arranged through one side of the bottom plate (4). A chute (6) is opened on the surface of the reinforcement frame (1). A plurality of sliders (7) are slidably connected in the inner cavity of the chute (6). One side of the slider (7) is fixedly connected to the fixing plate (3).

5. The construction method of the anti-deformation shield tunnel with small clear distance passing under the existing tunnel according to claim 4, characterized in that: Two second fixing bolts (8) are arranged through the top of the mounting plate (2), and the number of the second fixing bolts (8) is four.

6. The construction method of a shield tunnel with anti-deformation for small clear distance under-crossing an existing tunnel according to claim 4, characterized in that: Anti-slip lines (9) are arranged on the surface of the reinforcement frame (1).

7. The construction method of a shield tunnel with anti-deformation for small clear distance undercrossing an existing tunnel according to claim 4, characterized in that: Limit grooves (10) are opened on both sides of the inner cavity of the chute (6). A limit block (11) is slidably connected in the inner cavities of the limit groove (10) and the chute (6). One side of the limit block (11) is fixedly connected to the slider (7).

8. Construction method of a shield tunnel with anti-deformation for small clear distance under-crossing an existing tunnel, characterized in that: The implementation steps of the reinforcement structure are as follows: Step 1: When using the reinforcement structure, place the reinforcement frame (1) in the shield tunnel. The fixing bolt two (8) tightly connects the mounting plate (2) to the tunnel. The operating slider (7) slides in the inner cavity of the chute (6) to adjust the relative position of the fixing plate (3) and the reinforcement frame (1). During this process, continuous observation and adjustment are required to find the best fixing points; Step 2: As the fixing plate (3) moves, the bottom plate (4) will move in the same direction. When the fixing plate (3) moves to the predetermined position, the two fixing bolts one (5) passing through one side of the bottom plate (4) are used to achieve the stable connection between the tunnel and the reinforcement frame (1). Since the number of the fixing plates (3) and the bottom plates (4) is several, the overall stability of the reinforcement frame (1) is enhanced. When the slider (7) moves, it will drive the limiting block (11) to slide in the inner cavity of the limiting groove (10), making it difficult for the bottom plate (4) and the fixing plate (3) to fall.

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