A structure of a secondary lining in a tunnel excavation serving as a shield launching reaction force device

Abstract

This utility model discloses a structure for a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device. It includes a first primary support, a first secondary lining inside the first primary support, a second secondary lining on the sides of the first primary support and the first secondary lining, mortar anchor bolts on the outer side of the second secondary lining, a second primary support outside the second secondary lining, a shield machine front face on the right side of the first primary support, fiberglass anchor bolts inside the shield machine front face, and a concrete island platform at the bottom of the inner wall of the first secondary lining. The unit price of concrete is much lower than that of steel, and by utilizing the stress characteristics of concrete, costs are saved. Using a reinforced concrete structure reduces the structural dimensions and working space of the steel support, avoiding large-scale excavation. Furthermore, the reinforced concrete ring beam can later serve as a permanent secondary lining structure, reducing subsequent demolition, cutting, and other procedures and labor costs, further saving costs.

Description

Technical Field

[0001] This utility model relates to the field of tunnel construction technology, and in particular to a structure that serves as both the secondary lining of a mined tunnel and a shield tunneling starting reaction device. Background Technology

[0002] With the rapid development of urban construction, the functional requirements of subways and the terrain they need to deal with are becoming increasingly complex. The geological conditions of shield tunnels are becoming more and more varied, and the application environment is becoming wider and wider. The shield launching reaction frame plays a crucial role in shield construction. It can not only provide stable support for the shield machine and ensure that it advances accurately according to the predetermined trajectory, but also effectively guarantee the safety of construction and improve construction efficiency.

[0003] Conventional shield tunneling starting reaction frames use steel ring plates, horizontal and vertical or diagonal steel supports, and multiple brackets. The main requirements for the reaction frame to ensure successful shield tunneling starting are to provide sufficient reaction force and controllable stability to ensure accurate and stable shield tunneling starting.

[0004] The initial reaction frame is primarily subjected to the thrust of the tunnel boring machine (TBM) during the initial launch phase. The reaction frame's overall stress, the stress on local steel components, the stress on welded steel members, and the stress on bolted connections all need to meet requirements. The entire system is spatially complex. To ensure the stability of the reaction frame, the reaction force transmitted from the TBM must be transmitted and offset through horizontal, vertical, or diagonal steel supports. Sufficient working space is required to ensure the safe installation and dismantling of these steel supports, leading to wasted excavation space. The accuracy of the reaction frame's position determines the accuracy of the TBM's launch direction. The assembly precision and welding connections of the steel structure components require high precision. After conventional TBM launch, once the TBM has excavated to a certain length, the reaction frame and steel supports need to be cut, dismantled, and recycled. Since steel is more expensive than concrete, concrete can be considered as a substitute when conditions permit. Welding and cutting are all performed in confined spaces, resulting in a poor working environment. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model provides a structure that serves as both the secondary lining of a mined tunnel and a shield tunneling starting reaction device, thereby solving the aforementioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A structure for a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device includes a first primary support, a first secondary lining disposed inside the first primary support, a second secondary lining disposed on the sides of the first primary support and the first secondary lining, mortar anchor bolts disposed on the outer side of the second secondary lining, a second primary support disposed on the outer side of the second secondary lining, a shield machine front face disposed on the right side of the first primary support, glass fiber anchor bolts disposed inside the shield machine front face, and a concrete island platform disposed at the bottom of the inner wall of the first secondary lining.

[0007] Preferably, the first primary support is made of concrete, and the concrete grade of the first primary support is C35.

[0008] Preferably, the first and second linings are made of concrete, and the concrete grade of the first and second linings is C35.

[0009] Preferably, the fiberglass anchor rod has a steel grade of HRB22, a length of 6.0m, and a spacing of 1.5m x 1.5m.

[0010] Preferably, the front face of the tunnel boring machine is made of C25 shotcrete, and the thickness of the front face of the tunnel boring machine is 150mm.

[0011] Preferably, the length of the mortar anchor is 5m and the ring spacing of the mortar anchor is 1m.

[0012] Preferably, the second lining is made of reinforced concrete, and the concrete grade of the second lining is C35.

[0013] Compared with existing technologies, the beneficial effects of this utility model are as follows: The secondary lining of this mined tunnel also serves as the shield tunneling starting reaction device. Conventional reaction frames use steel supports for horizontal and vertical support, requiring an additional increase in the excavation cross-section to accommodate manual work. Using a reinforced concrete structure reduces the structural dimensions of the steel supports and the required workspace, avoiding large-scale over-excavation. This application uses a reinforced concrete scheme, and the concrete is homogeneous and round, ensuring uniform stress distribution and high reliability. In reinforced concrete structures, the concrete is primarily subjected to compression, while tension, bending, and shear are shared by both concrete and reinforcing steel. The design value for the axial compressive strength of C35 concrete is 16.7 N / m², and the design value for the axial tensile strength of 555 concrete is 1.57 N / m². The design values ​​for the compressive, tensile, and shear strengths of HRB400 reinforcing steel are 360 ​​N / m². If a conventional initial reaction frame is used, the design values ​​for the tensile, compressive, and bending strengths of steel (taking Q345 as an example) are 330 N / m², and the shear strength is 190 N / m². Using reinforced concrete components can fully utilize the characteristics of each material. This project, after calculation, uses a ring beam structure approximately 2.5m wide and 2.1m high, which also serves as the initial reaction frame, meeting the stress requirements of both the initial reaction frame and the permanent structure. This saves materials; based on market prices, the unit price of concrete is much lower than that of steel. By fully utilizing the characteristics of concrete based on its stress properties, costs are saved. Furthermore, the reinforced concrete ring beam will later serve as a permanent secondary lining structure, reducing subsequent demolition, cutting, and other procedures and labor costs, further saving costs. Attached Figure Description

[0014] Figure 1 This is a three-dimensional perspective view of the present invention; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This utility model Figure 2 Enlarged view of point A in the middle; Figure 4 This utility model Figure 2 Enlarged view of point B in the middle.

[0015] In the diagram: 1. First primary support; 2. First secondary lining; 3. Mortar anchor; 4. Second primary support; 5. Tunnel boring machine face; 6. Second secondary lining; 7. Concrete island platform; 8. Fiberglass anchor. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example: Refer to Figure 1-4A structure for a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device includes a first primary support 1, made of concrete of grade C35. The primary support 1 is constructed using concrete, which facilitates its fabrication and ensures high strength. A first secondary lining 2, also made of concrete of grade C35, is located inside the primary support 1. This construction also facilitates the secondary lining 2's fabrication and ensures high strength. A second secondary lining 6, also made of concrete of grade C35, is located on the sides of the primary support 1 and the secondary lining 2. Mortar anchors 3, 5m in length and 1m in spacing between rings, are installed on the outer side of the second secondary lining 6 to reinforce it. The second secondary lining 6 is constructed of reinforced concrete of grade C35, which enhances its fabrication. This design is relatively convenient and allows for more stable use of the second secondary lining 6. A second primary support 4 is installed on the outer side of the second secondary lining 6. The shield machine face 5 is located to the right of the first primary support 1. The shield machine face 5 is made of C25 shotcrete with a thickness of 150mm. Fiberglass anchors 8 are installed inside the shield machine face 5. The steel grade of the fiberglass anchors 8 is HRB22, and the length of the fiberglass anchors 8 is 6.0m, with a spacing of 1.5m x 1.5m. By installing fiberglass anchor bolts 8, the strength of the tunnel boring machine's (TBM) front face 5 can be improved, facilitating more stable use of the TBM front face 5. A concrete island platform 7 is installed at the bottom of the inner wall of the first and second linings 2. The secondary lining of this cut-and-cover tunnel also serves as the structure for the TBM's starting reaction force device. Since conventional reaction frames use steel supports for horizontal and vertical support, considering the need for manual working space, the excavation cross-section needs to be increased. Using a reinforced concrete structure can reduce the structural dimensions of the steel supports and the working space, avoiding large-scale over-excavation. This application adopts a reinforced concrete scheme, and the concrete is homogeneous and round, resulting in uniform stress distribution and high reliability. In reinforced concrete structures, the concrete is primarily subjected to compression, while tension, bending, and shear are shared by both concrete and reinforcing steel. The design value for the axial compressive strength of C35 concrete is 16.7 N / m², and the design value for the axial tensile strength of 555 concrete is 1.57 N / m². The design values ​​for the compressive, tensile, and shear strengths of HRB400 reinforcing steel are 360 ​​N / m². If a conventional initial reaction frame is used, the design values ​​for the tensile, compressive, and bending strengths of steel (taking Q345 as an example) are 330 N / m², and the shear strength is 190 N / m². Using reinforced concrete components can fully utilize the properties of each material. Calculations for this project show that a ring beam structure approximately 2.5m wide and 2.1m high is used, which also serves as the initial reaction frame, meeting the stress requirements of both the initial reaction frame and the permanent structure, thus saving materials.Based on market prices, the unit price of concrete is much lower than that of steel. By fully utilizing the properties of concrete according to its stress characteristics, costs can be saved. Furthermore, the reinforced concrete ring beam can later serve as a permanent secondary lining structure, reducing subsequent demolition, cutting, and other procedures and labor costs, further saving costs.

[0018] In use: following the tunnel excavation procedure of the mining method, first construct the first initial support 1 with C35 concrete, then construct the first secondary lining 2 with C35 concrete, and so on until the shield launching section, so as to facilitate subsequent construction. Concrete island 7 can be constructed to the permanent structural working face with C35 concrete. To ensure the stability of the tunnel face before the shield machine advances, HRB22 grade glass fiber anchor rods 8 are installed at the front face 5 of the shield machine, with a length of six meters and a spacing of 1.5m x 1.5m. After the anchor rods are installed, shotcrete is sprayed to form the front face 5 of the shield machine. The launching reaction frame is integrated with the first and second linings 2 concrete, as follows: To meet the launching reaction force requirements, the reinforced concrete at the launching reaction frame location needs to be locally enlarged. To ensure uniform stress distribution, a homogeneous circular shape is used. Mortar anchors 3, 5 meters long with a 1-meter ring spacing, are first installed above the rail surface. The second initial support 4, which also serves as the launching reaction structure ring beam, is pre-supported using C35 concrete. To ensure the stability of the launching reaction frame, I-beams are used internally in the second initial support 4. After the second initial support 4 reaches 85% of its design strength, waterproofing is carried out according to mining methods, and the second lining 6, which also serves as the shield tunneling launching reaction device, is poured, using C35 concrete. To ensure accurate shield launching, the verticality of the second lining 6 is ensured.

[0019] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A structure for a secondary lining of a mined tunnel that also serves as a shield tunneling starting reaction device, comprising a first initial support (1), characterized in that, The first primary support (1) is provided with a first secondary lining (2) on the inner side, and a second secondary lining (6) is provided on the sides of the first primary support (1) and the first secondary lining (2). A mortar anchor (3) is provided on the outer side of the second secondary lining (6), and a second primary support (4) is provided on the outer side of the second secondary lining (6). A shield machine front face (5) is provided on the right side of the first primary support (1), and a glass fiber anchor (8) is provided inside the shield machine front face (5). A concrete island platform (7) is provided at the bottom of the inner wall of the first secondary lining (2).

2. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The first primary support (1) is made of concrete, and the concrete grade of the first primary support (1) is C35.

3. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The first secondary lining (2) is made of concrete, and the concrete grade of the first secondary lining (2) is C35.

4. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The glass fiber anchor (8) has a steel grade of HRB22, a length of 6.0m, and a spacing of 1.5m x 1.5m.

5. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The front face (5) of the tunnel boring machine is made of C25 shotcrete, and the thickness of the front face (5) of the tunnel boring machine is 150mm.

6. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The length of the mortar anchor (3) is 5m, and the ring spacing of the mortar anchor (3) is 1m.

7. The structure of a secondary lining in a mined tunnel that also serves as a shield tunneling starting reaction device according to claim 1, characterized in that, The second secondary lining (6) is made of reinforced concrete, and the concrete grade of the second secondary lining (6) is C35.

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