Shield door opening structure system and method of construction thereof

Abstract

The application discloses a shield door hole structure system and a construction method thereof. The shield door hole structure system is used for solving the problems of long construction period and poor structural strength reliability of the existing shield door hole. The shield door hole structure system comprises an end wall arranged at a corresponding position of a free surface of a foundation pit support structure, at least one waist beam arranged in a horizontal direction and intersecting with the end wall, a pre-embedded steel ring pre-embedded at a corresponding position of the end wall and concentric with a door hole, a door hole seal fixedly connected with the pre-embedded steel ring, vertical supports arranged on both sides of the end wall along a vertical center line of the end wall and fixedly connected with the free surface of the end wall, a plurality of inclined supports supported between the vertical supports and a foundation pit bottom plate, and a concrete base arranged between the door hole seal and the foundation pit bottom plate and used for covering and supporting a bottom of the door hole seal. Compared with the construction of a conventional full-covering secondary lining structure of a shield starting foundation pit, the shield door hole structure construction can greatly save the construction period, reduce the construction cost and improve the construction efficiency.

Description

Technical Field

[0001] This invention application relates to the field of shield tunnel technology, specifically to a shield tunnel portal structure system and its construction method. Background Technology

[0002] As a key component in shield tunnel construction, the structural design and function of the shield tunnel portal have a crucial impact on the safety, stability, and subsequent operation of the tunnel.

[0003] As the entrance and exit for tunnel construction, the structural stability and sealing of the shield tunnel portal directly affect the safety of tunnel construction. The structure of the shield tunnel portal mainly includes the main portal structure and sealing devices. The main portal structure is usually a cast-in-place reinforced concrete structure with sufficient strength and rigidity to withstand the water and soil pressure inside and outside the tunnel, as well as various loads during construction. Portal types are diverse, including end-wall type, wing-wall type, and column type portals; the specific selection depends on factors such as geological conditions, tunnel cross-sectional dimensions, and construction requirements. The sealing device of the shield tunnel portal mainly consists of rubber curtain sheets, circular ring plates, fan-shaped flaps, and corresponding connecting bolts and washers. These components work together to form a reliable sealing system, preventing groundwater and sediment from seeping into the tunnel.

[0004] The existing shield tunnel portal structure construction generally adopts the sequential construction method, which involves excavating the foundation pit to the design elevation, lining the foundation pit with a full-coverage secondary lining structure, and then constructing the shield tunnel portal. Due to the large workload and long construction period of the full-coverage secondary lining structure, the construction period of the shield tunnel portal is delayed, which in turn affects the shield launch, resulting in slow overall construction progress and low efficiency. At the same time, the strength of the portal structure is affected by a variety of factors such as material selection, design parameters, and construction technology. The existing portal structure is mainly a cast-in-place portal ring beam. If any link fails, it will reduce the strength and reliability of the portal ring beam, making the shield launch a safety risk.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] In view of at least one of the above-mentioned technical problems, this disclosure provides a shield tunnel portal structure system and its construction method. It aims to solve the problems of long construction cycles and poor structural strength and reliability of existing shield tunnel portals.

[0007] According to one aspect of this disclosure, a shield tunnel portal structure system is provided, comprising an end wall located at a corresponding position on the open side of the foundation pit retaining structure, at least one horizontally arranged wainscoting intersecting the end wall and bearing force therewith, a pre-embedded steel ring embedded at a corresponding position on the end wall and concentric with the portal, a portal seal fixedly connected to the pre-embedded steel ring, vertical supports symmetrically arranged on both sides of the end wall along the vertical centerline of the end wall and fixedly connected to the open side of the end wall, a plurality of diagonal supports between the vertical supports and the foundation pit bottom plate, and a concrete base located between the portal seal and the foundation pit bottom plate for covering and supporting the bottom of the portal seal.

[0008] In some embodiments of this disclosure, the free surface of the foundation pit retaining structure used to correspond to the end wall is provided with a textured surface.

[0009] In some embodiments of this disclosure, the internal reinforcement of the end wall includes anchor bars embedded in the end wall.

[0010] In some embodiments of this disclosure, the end wall is a square structure with a width and height greater than the diameter of the shield tunnel by 1 to 4 m, and the thickness of the end wall structure is 0.8 to 2 m; the length of the waist beam is not less than the corresponding width of the end wall.

[0011] In some embodiments of this disclosure, the top surface of the vertical support is not lower than the plane corresponding to the narrowest point in the horizontal direction between the edge of the door opening and the edge of the end wall.

[0012] In some embodiments of this disclosure, the angle between the diagonal brace and the bottom plate of the foundation pit is 40° to 50°.

[0013] According to another aspect of this disclosure, a method for constructing a shield tunnel portal structure system is provided, comprising the following steps: (1) The end walls and waist beams are constructed and poured using the reverse construction method in sync with the excavation of the foundation pit, and pre-embedded steel rings and pre-embedded steel plates are embedded at the corresponding positions of the end walls and / or waist beams; before the construction of the end walls and waist beams, the corresponding open surfaces of the foundation pit retaining structure are roughened, and after high-pressure washing, an interface agent is applied. (2) The door seal, including the steel ring, the curtain rubber plate, the sealing brush, and the folding pressure plate, is bolted to the pre-embedded steel ring in sections. After the door seal is formed into a ring, the door seal is welded and fixed to the pre-embedded steel ring. (3) Vertical supports are fixedly installed at the corresponding pre-embedded steel plates on both sides of the end wall, and corresponding diagonal supports are fixedly installed between the vertical supports and the bottom plate of the foundation pit; (4) After the tunnel portal seal is installed and verified by measurement, a concrete base is poured at the bottom of the tunnel portal seal. The concrete base fills the corresponding space between the bottom surface of the tunnel portal seal and the bottom plate of the foundation pit.

[0014] In some embodiments of this disclosure, in step (1), the upper waist beam, the middle waist beam, the upper end wall between the upper waist beam and the middle waist beam, the lower waist beam, and the lower end wall between the middle waist beam and the lower waist beam are poured in sequence; and the corresponding internal reinforcement bars are tied in each pouring section from bottom to top.

[0015] In some embodiments of this disclosure, in step (3), the vertical support is welded to the pre-embedded steel plate, and before welding, the gap between the vertical support and the end wall is filled with steel plate or iron sheet.

[0016] One or more technical solutions provided in this application embodiment have at least the following technical effects or advantages: Compared with the construction of a fully covered secondary lining structure for a conventional shield tunneling starting pit, this shield tunneling portal structure only requires the construction of end wall and waist beams on the portal face before the shield machine can be lowered into the shaft for assembly. Furthermore, the use of a reverse construction method greatly saves construction time and reduces construction costs. In addition, the installation of the portal seal and the construction of vertical supports, diagonal braces, and concrete bases can be carried out simultaneously with the assembly of the shield machine, thereby further saving construction time and improving construction efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the shield tunnel portal structure system in one embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of the embedded steel plate in one embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the doorway structure inside the foundation pit in one embodiment of this application.

[0020] In the above figures, 1 is the foundation pit retaining wall, 2 is the end wall, 21 is the upper end wall, 22 is the lower end wall, 31 is the upper waist beam, 32 is the middle waist beam, 33 is the lower waist beam, 4 is the portal seal, 5 is the vertical brace, 6 is the diagonal brace, 7 is the concrete base, 8 is the embedded steel plate, and 81 is the fixing bar. Detailed Implementation

[0021] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer", "vertical", "horizontal", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] To address the technical problems of long construction cycles and relatively low structural strength and reliability of existing shield tunnel portal structures, this example discloses a shield tunnel portal structure system, taking open-cut excavation as an example. (See attached image.) Figure 1 It includes end walls, waist beams, portal seals 4, vertical supports 5, diagonal supports 6, and concrete base 7.

[0024] Considering that the construction of existing portal structures is generally carried out after the completion of the foundation pit retaining structure, along with the full-coverage secondary lining structure of the foundation pit, this will delay the construction period of the portal structure and hinder the overall construction progress of the project. Therefore, in this embodiment, after the completion of the foundation pit retaining structure, i.e., the foundation pit retaining wall 1, an end wall is poured at the open surface of the wall corresponding to the shield tunnel portal. The end wall is made of reinforced concrete, and its structural width and height are increased by 1m to 4m compared to the diameter of the shield tunnel, and its structural thickness is 0.8m to 2m. The structural form is square. Thus, the stability of the foundation pit wall where the portal is located can be ensured by the end wall, avoiding the safety accidents caused by the disturbance of the portal structure during the initial excavation. Since the end wall is constructed after the foundation pit retaining structure is completed, and to ensure its reliable stabilizing effect, a reliable connection between the end wall and the foundation pit retaining structure is necessary. Therefore, in this embodiment, the free-faced surface of the foundation pit retaining structure, i.e., the foundation pit retaining wall, is textured with raised and recessed patterns. This textured surface increases the bonding strength between the end wall and the foundation pit retaining wall, ensuring a good bond. Furthermore, in this embodiment, an interface layer is provided between the free-faced surface of the foundation pit retaining wall and the end wall. This interface layer is formed by the solidification of an interface agent, further increasing the bonding strength between the foundation pit retaining wall and the end wall. To further improve the bonding effect between the foundation pit retaining wall and the end wall, in this example, several anchor bars are embedded within the foundation pit retaining wall. Each anchor bar is connected and fixed to the internal reinforcement of the end wall. These anchor bars are inserted to a certain depth into the pit wall and reliably anchored there, thus preventing the sequential pouring of the foundation pit retaining wall and the end wall from affecting their bonding effect and overall structural integrity.

[0025] Considering the limited area of ​​the end wall, to ensure the foundation pit retaining structure does not taper inward and to improve the foundation pit support effect, in this embodiment, wainscoting is installed at the top, middle, and bottom of the end wall. The length of the wainscoting is longer than the corresponding length of the end wall, and both ends of the wainscoting extend a certain length beyond the sides of the end wall. This wainscoting increases the load-bearing capacity of the end wall and ensures the foundation pit support effect. In other embodiments, wainscoting is selectively installed at different locations based on the foundation pit structure and end wall load calculations. Similarly, during the pouring and construction of the wainscoting, the corresponding exposed surface of the foundation pit retaining wall is also provided with a textured surface to enhance the bonding strength, and an interface layer is provided at the joint between the two. Furthermore, to further improve the bonding strength, anchor bars, fixed to the inner reinforcement of the wainscoting, are added and anchored to the corresponding pit wall. Thus, the cooperation between the wainscoting and the end wall achieves reliable support for the foundation pit retaining wall where the shield tunnel portal is located, preventing the foundation pit wall from tapering inward.

[0026] In this embodiment, considering the need for portal seals during actual use to prevent external soil and water from entering the working shaft through the gap between the portal and the tunnel boring machine (TBM) or tunnel segments, thus affecting construction safety, a pre-embedded steel ring matching the portal seal is pre-embedded within the end wall during the construction of the end wall and corresponding girders. The diameter of this pre-embedded steel ring matches the diameter of the portal seal, allowing them to overlap. Furthermore, the center of the pre-embedded steel ring is aligned with the center of the TBM portal to prevent interference between the TBM and the ring during tunneling, thus avoiding impacts on tunneling and the portal structure. To ensure the bonding strength between the pre-embedded steel ring and the end wall, a groove is provided on the circumferential side of the pre-embedded steel ring. The corresponding end of the end wall reinforcement located outside the pre-embedded steel ring is placed within this groove, causing positional interference and preventing the pre-embedded steel ring from detaching from the end wall, thus ensuring the pre-embedded strength of the steel ring. In some other embodiments, to further improve the reliability of the connection between the embedded steel ring and the end wall, the inner reinforcement of the end wall is welded and fixed to the embedded steel ring.

[0027] In this example, the portal seal is in the form of a block and is composed of steel rings, curtain rubber rings, sealing brushes, folding pressure plates and other components. During installation, each block is fixed to the pre-embedded steel rings embedded in the end wall in sequence. Since the pre-embedded steel rings are firmly and reliably fixed in the end wall, the stability of the portal seal connection can be guaranteed.

[0028] However, in order to improve the reliability of the doorway structure, in this embodiment, see... Figure 1Vertical supports 5 are also provided on both sides of the end wall. These vertical supports 5 are perpendicular to the bottom slab of the foundation pit, and their bottom surfaces are coplanar with the bottom slab of the foundation pit. In this example, the end wall is a square structure. Therefore, the structure of the end wall at the widest part of the portal is relatively weak in the horizontal direction. After the tunnel boring machine passes through the portal, it is difficult to guarantee the structural strength of the portal. Therefore, in this example, the vertical supports 5 on both sides of the end wall provide support. The vertical supports on both sides are symmetrically arranged about the vertical centerline of the end wall, and the top surface of the vertical support 5 is not lower than the plane corresponding to the narrowest part of the horizontal direction between the excavation edge of the portal and the edge of the end wall. This allows the vertical supports to provide strong support to the weak structural part of the end wall, so that the portal structure always maintains reliable structural strength.

[0029] To ensure the vertical supports provide effective protection, in this embodiment, steel plates are pre-embedded at the corresponding support locations during the construction of the end wall. (See attached diagram.) Figure 2 The embedded steel plate 8 has several fixing ribs 81 on one side, which allows the embedded steel plate to be stably connected to the end wall through the interlaced fixing ribs 81. In this example, the vertical support is made of steel profile, and the fixed connection between the vertical support and the embedded steel plate at the end wall ensures that the load can be effectively transferred to the vertical support when the pit wall deforms.

[0030] See Figure 1 In this example, several diagonal braces 6 are installed between the vertical brace 5 and the foundation pit floor slab. One end of each diagonal brace is supported at the vertical brace, and the other end is supported at the foundation pit floor slab. In this example, the diagonal braces 6 are also made of steel, thus ensuring a secure connection between the diagonal braces and the vertical brace and guaranteeing connection strength. Additionally, a pre-embedded steel plate 8 is embedded in the foundation pit floor slab to fix the diagonal braces, preventing relative slippage between the diagonal braces and the foundation pit floor slab that would affect the support effect. Therefore, after deformation of the pit wall corresponding to the tunnel opening, the load can be transferred to the foundation pit floor slab through the vertical and diagonal braces for release, thereby ensuring the structural safety of the tunnel opening. In this embodiment, the angle between the diagonal brace 6 and the foundation pit floor slab is 45 degrees, achieving excellent support effect. In other embodiments, the angle between the diagonal brace 6 and the foundation pit floor slab is other angle values ​​between 40° and 50°. Thus, by strengthening the connection between the diagonal brace and the end wall through the vertical brace, stress concentration is avoided, preventing it from affecting the structural strength of the end wall.

[0031] In addition, since the portal seal has a certain thickness, it will protrude from the end wall when it is fixed to the open surface of the end wall. In order to avoid adverse effects on the structural strength of the shield tunnel portal, in this embodiment, a concrete base is poured between the portal seal and the foundation pit bottom plate to cover the bottom portal seal. The strength of the concrete and the adhesion between the concrete base and the portal seal are used to increase the rigidity and impermeability.

[0032] In other embodiments, the shield tunnel portal structure system is used for open-slope foundation pits and mine tunnel portal launching pits.

[0033] This example also discloses a construction method for a shield tunnel portal structure system. See [link to relevant documentation] Figure 3 Specifically, it includes the following steps: (1) The end walls and waist beams were poured using the reverse construction method simultaneously with the excavation of the foundation pit.

[0034] To save construction time, in this embodiment, the end walls and corresponding lintels are constructed using the reverse construction method, proceeding simultaneously with the foundation pit excavation. As the foundation pit excavation progresses, see [link to relevant documentation]. Figure 1 The upper waist beam 31, the middle waist beam 32, the upper end wall 21 between the upper waist beam 31 and the middle waist beam 32, the lower waist beam 33, and the lower end wall 22 between the middle waist beam 32 and the lower waist beam 33 are constructed in sequence.

[0035] Specifically, in this embodiment, to enhance the bond strength between the end walls and wainscoting and the foundation pit retaining structure, the joint areas of the end walls and wainscoting corresponding to the foundation pit retaining wall are roughened to create a textured surface, exposing fresh concrete. This increases the contact area between the concrete of the end walls and wainscoting and the foundation pit retaining wall, thereby strengthening the connection quality between the old and new concrete. After roughening the foundation pit retaining wall, the roughened surface is rinsed with high-pressure water to ensure that there is no dust, dirt, or other adhering substances. After the surface dries, an interface agent is applied between the contact surfaces of the end walls and the foundation pit retaining structure to form an interface layer, stabilizing the connection between the end walls and wainscoting and the foundation pit retaining wall. In each pouring section, the corresponding internal reinforcement bars are tied and the positioning bars are installed sequentially from bottom to top, progressively improving the overall stability and reliability of the reinforcement arrangement. In this example, after roughening the retaining wall of the foundation pit and before high-pressure flushing, anchor bars are inserted into the corresponding locations on the pit wall. During the reinforcement binding, the anchor bars are fixedly connected to the internal reinforcement of the end wall and / or the lintel, thereby further improving the bonding strength between the end wall and the retaining wall. Before pouring the end wall and lintel, embedded steel rings and plates are installed at corresponding locations on the end wall to provide reliable fixing points for subsequent portal sealing and vertical bracing. During the pouring operation, concrete is poured in layers of 300mm to 500mm in height.

[0036] Therefore, the shield tunnel portal structure can be constructed simultaneously with the foundation pit excavation using the reverse construction method, and there is no need to erect a scaffolding support system from the bottom of the foundation pit upwards. Compared with the conventional method of constructing the shield tunnel portal after the construction of the full-coverage secondary lining structure, it can save 30 to 70 days of construction time and reduce project investment by about 5 million to 8.9 million yuan.

[0037] In some other embodiments, anchor bolts or anchor cables are simultaneously installed on other sidewalls of the pit during excavation as an auxiliary reinforcement measure to enhance the stability of the pit structure.

[0038] (2) The portal sealing blocks are bolted together in sequence at the pre-embedded steel ring, and the portal sealing is welded and fixed to the pre-embedded steel ring after the portal sealing is formed into a ring.

[0039] After the end wall and waist beam are constructed, the portal seal is installed. In this embodiment, the portal seal is in a segmented form, with each segment installed sequentially. The segments are connected by bolts and finally assembled into a ring. During installation, each segment of the portal seal is connected to the pre-embedded steel ring at the end wall. After the portal seal is assembled into a ring, it is then welded and fixed to the pre-embedded steel ring, ensuring the strength and reliability of the connection between the two.

[0040] (3) Vertical supports are fixedly installed at the corresponding embedded steel plates on both sides of the end wall, and corresponding diagonal supports are fixedly installed between the vertical supports and the bottom plate of the foundation pit.

[0041] In this embodiment, the installation of the portal seal and the vertical bracing are carried out simultaneously to shorten the construction period. Furthermore, the installation of the portal seal, vertical bracing, and diagonal bracing is synchronized with the assembly of the tunnel boring machine, thereby further saving construction time. In this embodiment, the vertical bracing uses I-beams, which are welded to the embedded steel plates at the end walls. The contact surfaces between the I-beam structure and the embedded steel plates are fully welded. Before welding, steel plates or sheet metal are used to fill the gaps between the vertical bracing and the end walls until they are tight, thereby ensuring reliable and uniform stress transfer. After the vertical bracing is securely installed, diagonal bracing is installed between the vertical bracing and the embedded steel plates at the bottom of the pit. The diagonal bracing is set at a 45-degree angle to the ground, and both ends of the diagonal bracing are fully welded to the vertical bracing and the embedded steel plates at the bottom of the pit, respectively. This achieves effective stress transfer from the pit to the bottom of the pit through the end walls, vertical bracing, and diagonal bracing.

[0042] (4) After the tunnel portal seal is installed and verified by measurement, a concrete base is poured at the bottom of the tunnel portal seal. The concrete base fills the corresponding space between the bottom surface of the tunnel portal seal and the bottom plate of the foundation pit.

[0043] The concrete base is made of cast-in-place concrete to completely seal and enclose the bottom portal. The strength of the concrete and its adhesion to the portal seal achieve both support rigidity and impermeability. In this embodiment, the concrete base is plain concrete. Specifically, before pouring the concrete base, the contact surfaces of the foundation pit bottom slab, end walls, and portal sealing steel ring with the concrete base are cleaned to remove debris or rust. Then, the formwork is installed. After the concrete is poured and cured, the compactness of the concrete is checked. In this example, an ultrasonic testing instrument is used to check the compactness, and any voids in the poured concrete are addressed promptly.

[0044] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0045] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of its inventive concept. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for constructing a shield tunnel portal structure system, characterized in that, Includes the following steps: (1) The end walls and waist beams are constructed and poured using the reverse construction method in sync with the excavation of the foundation pit, and pre-embedded steel rings and pre-embedded steel plates are embedded at the corresponding positions of the end walls and / or waist beams; before the construction of the end walls and waist beams, the corresponding open surfaces of the foundation pit retaining structure are roughened, and after high-pressure washing, an interface agent is applied. (2) The door seal, including the steel ring, the curtain rubber plate, the sealing brush, and the folding pressure plate, is bolted to the pre-embedded steel ring in sections. After the door seal is formed into a ring, the door seal is welded and fixed to the pre-embedded steel ring. (3) Vertical supports are fixedly installed at the corresponding pre-embedded steel plates on both sides of the end wall, and corresponding diagonal supports are fixedly installed between the vertical supports and the bottom plate of the foundation pit; (4) After the tunnel portal seal is installed and verified by measurement, a concrete base is poured at the bottom of the tunnel portal seal. The concrete base fills the corresponding space between the bottom surface of the tunnel portal seal and the bottom plate of the foundation pit.

2. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, In step (1), the upper waist beam, the middle waist beam, the upper end wall between the upper waist beam and the middle waist beam, the lower waist beam, and the lower end wall between the middle waist beam and the lower waist beam are constructed in sequence; and the corresponding internal reinforcement bars are tied in each casting section from bottom to top.

3. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, In step (3), the vertical brace is welded to the pre-embedded steel plate, and before welding, the gap between the vertical brace and the end wall is filled with steel plate or iron sheet.

4. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, The exposed surface of the foundation pit retaining structure used to connect with the end wall has a textured surface.

5. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, The internal reinforcement of the end wall includes anchor bars embedded in the end wall.

6. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, The end wall is a square structure, with a width and height greater than the diameter of the shield tunnel by 1 to 4 meters, and a thickness of 0.8 to 2 meters; the length of the waist beam is not less than the corresponding width of the end wall.

7. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, The top surface of the vertical support is not lower than the plane corresponding to the narrowest point in the horizontal direction between the edge of the doorway excavation and the edge of the end wall.

8. The method for constructing the shield tunnel portal structure system according to claim 1, characterized in that, The angle between the diagonal brace and the bottom plate of the foundation pit is 40° to 50°.

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