Shield end reinforcing method and structure

Abstract

The invention discloses a shield end reinforcing method and structure. The shield end reinforcing method is achieved through surrounding environment investigation, fence construction, site leveling, cast-in-situ bored pile construction, front retaining wall and side retaining wall construction, plain concrete backfilling, shield tunneling and greening protection. Comprising a cast-in-situ bored pile, a front retaining wall, a side retaining wall and shield tunneling machine holes, the cast-in-situ bored pile is arranged below the front retaining wall, the two shield tunneling machine holes are formed in the front retaining wall, and the center line of a shield tunnel left line of the shield tunneling machine hole on the left side is parallel to the center line of a shield tunnel right line of the shield tunneling machine hole on the right side; the shield tunneling machine hole in the left side and the shield tunneling machine hole in the right side are located in the same horizontal plane, and plain concrete is backfilled in the front retaining wall and the side retaining walls. The shield end reinforcing structure has small influence on the built underground tunnel, reduces the tunnel entering risk of the shield tunnel in the shallow-buried unsymmetrical-pressure section, reduces interference and damage to a mountain, and avoids water and soil loss caused by construction in the flood season, so that the safety requirement is met, and safe tunnel entering of the shield tunneling machine is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tunnel construction, in particular to a shield end reinforcing method and structure. BACKGROUND

[0002] With the development of underground tunnel space, the shield tunnel has to be implemented under the complex conditions of adjacent existing underground tunnels (including railway tunnels, subway tunnels, urban underground tunnels, etc.), mountain side pressure, partial emptying, and poor surrounding rock grade of portal section. Due to the high protection requirements of adjacent existing underground tunnel structures, the shield tunnel is difficult to enter the hole under the conditions of mountain side pressure and partial emptying, and the construction risk of the shield tunnel of the portal section with poor surrounding rock grade is high, which poses a great challenge to the implementation of the shield tunnel.

[0003] Based on the above situation, the present application provides a shield end reinforcing method and structure to effectively solve the above problems. SUMMARY

[0004] In order to solve the problems in the background art, the present application provides a shield end reinforcing method and structure.

[0005] The present application adopts the following technical solutions:

[0006] A shield end reinforcing method, comprising the following steps:

[0007] Step one, investigation of the surrounding environment: engineering geological data, existing structures and the surrounding environment, the existing structure refers to the adjacent existing railway tunnel data; the data includes bearing capacity limit, normal use limit, durability, etc.

[0008] Step two, construction of the enclosure, site leveling: after the completion of the investigation of the surrounding environment, the enclosure is constructed, the vegetation and floating soil on the ground within the enclosure are removed, and after the surface is cleaned, the ground is compacted and leveled by machinery; the site leveling line 1 is the ground surface after the ground is cleaned and leveled.

[0009] Step three, construction of bored piles, the distance between the bored piles and the length of the piles can be comprehensively valued according to the actual situation of the stratum and the requirements for the bearing capacity of the foundation; the comprehensive valuation includes the bearing capacity (including instability) calculation value of the structural members, the fatigue calculation value of the members directly bearing repeated loads, the seismic bearing capacity calculation value when there is a requirement for seismic fortification, and the overturning, sliding and floating calculation values of necessary structures, etc.

[0010] For the permanent design condition, the temporary design condition and the seismic design condition, when the form of force is expressed, the structural members should use the bearing capacity limit state expression:

[0011] γ0S≤R

[0012] R=R(f c,f s ,a k ,…) / γ Rd

[0013] In the formula: r0 is the structural importance coefficient: under both sustained and short-term design conditions, it should not be less than 1.1 for structural members with a safety level of 1, not less than 1.0 for structural members with a safety level of 2, and not less than 0.9 for structural members with a safety level of 3; it should be 1.0 under seismic design conditions.

[0014] S is the design value of the effect of the action combination under the ultimate limit state of bearing capacity: for persistent design conditions and transient design conditions, it should be calculated according to the basic combination of actions; for seismic design conditions, it should be calculated according to the seismic combination of actions.

[0015] R is the design resistance value of the structural member;

[0016] R(■) is the resistance function of the structural member;

[0017] rRd is the uncertainty coefficient of the resistance model of structural members: it is taken as 1.0 for static design, and a value greater than 1.0 is taken for structural members with large uncertainties according to the specific situation; the bearing capacity seismic adjustment coefficient rRE is used instead of rRd for seismic design.

[0018] fc and fs are the design strength values ​​of concrete and steel reinforcement, respectively.

[0019] ak is the standard value of the geometric parameter. When the variability of the geometric parameter has a significant adverse effect on the structural performance, an additional value should be added or removed.

[0020] Step 4: Construct the front and side retaining walls: After the bored piles are completed and tested to meet the requirements, excavate the foundations of the front and side retaining walls to form temporary slopes, and then pour the front and side retaining walls. The front and side retaining walls are poured as a whole at the same time, and the front and side retaining walls are placed on a stable foundation. If the bearing capacity cannot meet the requirements, the foundation needs to be treated. The bearing capacity requirements must comply with the Code for Design of Concrete Structures GB 50010-2010.

[0021] Step 5: Plain concrete backfilling: After the retaining wall reaches the required strength, the inner side of the front and side retaining walls is backfilled with plain concrete and compacted. A layer of steel mesh is installed 45mm above the top surface of the plain concrete backfill. The specifications and spacing of the steel bars used can be determined according to the actual site conditions.

[0022] Step Six: Tunnel Boring Machine (TBM) Enters the Tunnel: After the backfilled solid concrete reaches the required strength, the TBM begins excavation and the lining segments are constructed.

[0023] Step 7: Greening and Protection: Backfill the solidified roof with planting soil and greening and protection measures to ensure that the greening is in harmony with the surrounding natural environment.

[0024] Furthermore, the existing railway tunnel data includes the location, structural dimensions, burial depth, and existing deformation data of the railway tunnels.

[0025] Furthermore, the surrounding environment refers to the topography, existing pipelines, and existing buildings and structures surrounding the proposed site for the shield tunnel.

[0026] Furthermore, the structure based on a shield tunnel end reinforcement method includes bored piles, a front retaining wall, side retaining walls, and shield tunneling machine tunnels. Bored piles are provided below the front retaining wall, and two shield tunneling machine tunnels are provided inside the front retaining wall. The center line of the left tunnel of the shield tunnel of the left shield tunnel is parallel to the center line of the right tunnel of the shield tunnel of the right shield tunnel. The left shield tunnel and the right shield tunnel are the same size and are on the same horizontal plane. Plain concrete is backfilled inside the front retaining wall and the side retaining wall.

[0027] Furthermore, the side retaining wall is a sloping surface.

[0028] Furthermore, a steel mesh is installed 45mm away from the top surface of the plain concrete.

[0029] Furthermore, the area between the front retaining wall and the bored piles is a leveled ground line.

[0030] Furthermore, a railway tunnel is located below the ground level on one side of the front retaining wall.

[0031] Furthermore, the outer edges of the two tunnel boring machine tunnels are at the same horizontal level.

[0032] Furthermore, the front retaining wall and the side retaining walls are cast as a single integrated structure.

[0033] The present invention provides a shield tunnel end reinforcement method and structure: it has little impact on existing underground tunnels, reduces the risk of shield tunnels entering the tunnel in shallow buried biased pressure sections, and can reduce interference and damage to the mountain, avoid soil erosion caused by construction during the flood season, so that the permanent deformation of existing underground tunnels caused by shield tunneling meets safety requirements, and enables the shield machine to enter the tunnel safely. Attached Figure Description

[0034] Fig. 1 This is a schematic diagram of the overall structure of the present invention.

[0035] Fig. 2 This is a schematic diagram of the front retaining wall of the present invention.

[0036] Fig. 3 This is a cross-sectional schematic diagram of the present invention.

[0037] The numbers marked in the diagram represent the following in order: 1-site line, 2-drilled pile, 3-front retaining wall, 4-side retaining wall, 5-plain concrete, 6-center line of the left line of the shield tunnel, 7-center line of the right line of the shield tunnel, 8-center line of the railway tunnel, 9-ground line, 10-railway tunnel, 11-shield tunnel, 12-outer edge of the shield machine. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] See attached document Figs. 1-3 A method for reinforcing the end of a tunnel boring machine includes the following steps:

[0040] Step 1: Surrounding Environment Survey: Investigate the engineering geology, existing structures and surrounding environment. Existing structures refer to adjacent existing railway tunnels, including the location, structural dimensions, burial depth and existing deformation of the railway tunnels. Surrounding environment refers to the topography, existing pipelines (if any) and existing buildings and structures (if any) around the proposed shield tunnel site.

[0041] Step 2: Construction enclosure and site leveling: After the surrounding environment survey is completed, the construction enclosure is set up, vegetation and loose soil on the ground inside the enclosure are removed, and the surface is compacted and leveled by machinery after clearing; Site line 1 is the ground surface after clearing and leveling.

[0042] Step 3: Construct bored pile 2. The spacing and length of bored pile 2 can be determined comprehensively based on the actual conditions of the strata and the requirements for the bearing capacity of the foundation.

[0043] Step 4: Construct the front retaining wall 3 and the side retaining wall 4: After the bored pile 2 is completed and meets the requirements after testing, the foundation of the front retaining wall 3 and the side retaining wall 4 is excavated to form a temporary slope, and then the front retaining wall 3 and the side retaining wall 4 are poured. The front retaining wall 3 and the side retaining wall 4 are poured as a whole at the same time. The front retaining wall 3 and the side retaining wall 4 should be placed on a stable foundation. If the bearing capacity cannot meet the requirements, the foundation needs to be treated.

[0044] Step 5, Plain Concrete Backfilling: After the retaining wall reaches the required strength, backfill the inner side of the front retaining wall 3 and the side retaining wall 4 with plain concrete 5 and compact it. A layer of steel mesh should be installed 45mm above the top surface of the plain concrete 5 backfill. The specifications and spacing of the steel bars used can be determined according to the actual site conditions.

[0045] Step 6, Tunnel Boring: After the backfill of plain concrete 5 reaches the required strength, the tunnel boring machine (TBM) begins excavation and the lining segments are constructed.

[0046] Step 7, Greening and Protection: Backfill the solidified roof with planting soil and greening and protection to ensure that the greening is in harmony with the surrounding natural environment.

[0047] A shield tunnel end reinforcement structure includes bored piles 2, a front retaining wall 3, a side retaining wall 4, and a shield tunneling machine tunnel 11. The bored piles 2 are located below the front retaining wall 3. Two shield tunneling machine tunnels 11 are located inside the front retaining wall 3. The shield tunneling machine tunnel 11 includes two tunnels. The center line 6 of the left tunnel of the shield tunnel 11 is parallel to the center line 7 of the right tunnel of the shield tunnel 11. The left tunnel of the shield tunnel 11 and the right tunnel of the shield tunnel 11 are the same size and are on the same horizontal plane. Plain concrete 5 is backfilled in the front retaining wall 3 and the side retaining wall 4.

[0048] The side retaining wall 4 is a sloping surface.

[0049] A steel mesh is installed 45mm away from the top surface of plain concrete 5.

[0050] The area between the front retaining wall 3 and the bored pile 11 is the leveled ground line.

[0051] A railway tunnel 10 is located below the ground level on one side of the front retaining wall 3. Label 8 in the diagram indicates the centerline of the railway tunnel, used to show the center location of the tunnel.

[0052] The outer edges 12 of the two tunnel boring machine tunnels 11 are at the same horizontal level.

[0053] The front retaining wall 3 and the side retaining wall 4 are cast as a single unit.

[0054] Drilled pile foundations are a common method for deep foundation construction. They involve mechanically drilling holes to create pile bodies, then pouring concrete into these holes (usually after placing a reinforcing cage) to form the pile. Drilling machinery is used to drill holes of a certain diameter in the ground. Once these holes reach the designed depth, they are used to place the reinforcing cage and pour concrete. Construction steps include: ensuring the drilling rig is level and stable, and that the overhead crane, turntable, and pile center are aligned vertically; properly designing the drill bit, adding a centering ring to ensure smooth rotation; installing a guide device on the active drill rod to prevent excessive sway; and regularly checking the verticality of the drill rod.

[0055] Tubular lining segments are precast concrete components used for tunnel lining, playing a crucial role in tunnel construction. They are primarily used in underground engineering projects such as tunnels, subways, and water conservancy channels to prevent deformation or collapse of the surrounding rock. They are installed along the perimeter of the tunnel body to form a permanent support structure. Tubular lining segments are typically prefabricated in factories or on-site and then transported to the tunnel construction site for assembly. Based on different materials and manufacturing processes, they can be classified into types such as metal segments and reinforced concrete segments.

[0056] The site level line refers to the relatively flat ground elevation line formed after excavation and filling. It is determined during site leveling work. Site leveling involves transforming the original ground into a plane that meets the needs of construction, production, or living conditions by excavating higher areas and filling lower areas. This process involves calculating earthwork volumes and adjusting earthwork balance.

[0057] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for reinforcing the end of a tunnel boring machine, characterized in that, Includes the following steps: Step 1: Surrounding environment survey: engineering geological data, existing structures and surrounding environment, where existing structures refer to data on adjacent existing railway tunnels; Step 2: Construction enclosure and site leveling: After the surrounding environment survey is completed, the construction enclosure is set up, vegetation and loose soil on the ground inside the enclosure are removed, and the surface is compacted and leveled by machinery after clearing; the site leveling line is the ground surface after clearing and leveling. Step 3: Construct bored cast-in-place piles. The spacing and length of the bored cast-in-place piles can be determined comprehensively based on the actual conditions of the strata and the requirements for the bearing capacity of the foundation. Step 4: Construct the front and side retaining walls: After the bored piles are completed and tested to meet the requirements, the foundations of the front and side retaining walls are excavated to form temporary slopes, and then the front and side retaining walls are poured. The front and side retaining walls are poured as a whole at the same time, and the front and side retaining walls are placed on a stable foundation. If the bearing capacity cannot meet the requirements, the foundation needs to be treated. Step 5: Plain concrete backfilling: After the retaining wall has reached the required strength, the inner side of the front and side retaining walls is backfilled with plain concrete and compacted; a layer of steel mesh is placed on the top surface of the plain concrete backfill solid. Step Six: Tunnel Boring Machine (TBM) Enters the Tunnel: After the backfilled solid concrete reaches the required strength, the TBM begins excavation and the lining segments are constructed. Step 7, Greening and Protection: Backfill the solidified roof with planting soil and greening protection.

2. The shield tunnel end reinforcement method according to claim 1, characterized in that, Existing railway tunnel data includes the location, structural dimensions, burial depth, and existing deformation data of the railway tunnels.

3. The shield tunnel end reinforcement method according to claim 1, characterized in that, The surrounding environment refers to the topography, existing pipelines, and existing buildings and structures around the proposed site of the shield tunnel.

4. The structure of the shield tunnel end reinforcement method according to claim 1, characterized in that, The structure includes bored piles, a front retaining wall, side retaining walls, and tunnel boring machine (TBM) tunnels. Bored piles are installed below the front retaining wall. Two TBM tunnels are located inside the front retaining wall. The center line of the left tunnel of the left TBM tunnel is parallel to the center line of the right tunnel of the right TBM tunnel. The left TBM tunnel and the right TBM tunnel are the same size and on the same horizontal plane. Plain concrete is backfilled inside the front retaining wall and the side retaining wall. The side retaining wall is a sloping surface.

5. A shield tunnel end reinforcement structure according to claim 4, characterized in that, A steel mesh is installed 45mm away from the top surface of the plain concrete.

6. The shield tunnel end reinforcement structure according to claim 4, characterized in that, The area between the front retaining wall and the bored piles is the leveled ground line.

7. A shield tunnel end reinforcement structure according to claim 4, characterized in that, A railway tunnel is located below ground level on one side of the front retaining wall.

8. A shield tunnel end reinforcement structure according to claim 4, characterized in that, The outer edges of the two tunnel boring machine tunnels are at the same horizontal level.

9. A shield tunnel end reinforcement structure according to claim 4, characterized in that, The front retaining wall and the side retaining walls are cast as a single unit.

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