Super-large-diameter shield tunnel freezing connection channel prestress tunnel support

Abstract

The invention provides a super-large-diameter shield tunnel freezing connection channel prestress tunnel support which comprises a plurality of longitudinal supporting units and transverse supports, and the transverse supports are fixedly connected with every two adjacent longitudinal supporting units. The longitudinal supporting unit comprises an arc-shaped support, an inverted-U-shaped support and a plurality of short-circuit supports, the position of the arc-shaped support corresponds to the frozen contact channel and is connected with the inner wall of the tunnel, the upper left corner and the upper right corner of the inverted-U-shaped support are fixedly connected with the arc-shaped support, and the lower left corner and the lower right corner of the inverted-U-shaped support are fixedly connected with the lane plate; the short-circuit support is perpendicular to the inverted-U-shaped support and is fixedly connected with the arc-shaped support and the inverted-U-shaped support; the arc-shaped support is provided with a prestress device for providing internal prestress. The construction method has the beneficial effects that through the close fit design of the arc-shaped supports and the inner wall of the tunnel and the anchoring effect of the inverted-U-shaped supports on the lane plate, a stable space stress system is formed in the super-large-diameter tunnel during construction of the freezing connection channel.

Description

Technical Field

[0001] The present invention relates to the technical field of shield tunnels, and in particular to a prestressed tunnel support for a frozen connecting channel of an ultra-large diameter shield tunnel. Background Art

[0002] With the sustained and rapid development of my country's national economy and the accelerating pace of urbanization, transportation demand in major cities is growing annually. Underground transportation is being developed on a large scale to alleviate road congestion and improve the urban environment. Underground tunnel construction is booming, and the number of ultra-large-diameter shield tunnel projects (Shield tunnels with a diameter of 14 meters or greater, which can accommodate traffic needs of two-deck four-lane or single-deck three-lane tunnels, are referred to as ultra-large-diameter shield tunnels) is increasing year by year. Connecting passages, constructed between ultra-large-diameter twin tunnels, serve purposes such as connectivity, drainage, emergency evacuation, and fire prevention, and are a crucial component of tunnel construction. Currently, the vast majority of connecting passages in my country are still excavated using the mining method. In ultra-large-diameter tunnel projects in water-rich strata, the intersection between the tunnel and connecting passage, as well as the surrounding strata, is disturbed by construction, resulting in complex stress conditions. Excavating connecting passages underground presents significant risks, and even the slightest carelessness can lead to construction accidents such as water and sand gushing.

[0003] To reduce the construction risks of ultra-large-diameter shield tunnels, the vast majority of connecting passageways in my country are constructed using a combination of freeze reinforcement and underground excavation. The freeze method is a crucial construction method for traversing complex strata and water-rich soft soil. It utilizes artificial refrigeration to freeze water in the soil, forming a solid, closed permafrost ring that resists water and soil pressure and isolates groundwater. Excavation and construction proceed under the protection of the frozen wall.

[0004] Before freezing construction, freezing pipes are drilled into the ground. -28°C brine circulates through the pipes, freezing the soil's internal moisture to form frozen ground. Frost heaving and the excavation of connecting tunnels can cause segmental instability, necessitating the installation of tunnel supports. Existing tunnel supports are primarily designed for small-diameter tunnels and are unsuitable for large highway tunnels with portals. Summary of the Invention

[0005] In order to solve the problem that existing tunnel supports are mostly designed for small-diameter tunnels and are not suitable for large highway tunnels with opening components, the present invention provides a prestressed tunnel support for a frozen connecting channel of an ultra-large diameter shield tunnel, comprising a plurality of longitudinal support units and a transverse brace, wherein the transverse brace fixedly connects two adjacent longitudinal support units; The longitudinal support unit includes an arc support, an inverted U-shaped support and multiple short-circuit supports. The position of the arc support corresponds to the frozen connecting channel and is connected to the inner wall of the tunnel. The upper left and upper right corners of the inverted U-shaped support are fixedly connected to the arc support, and the lower left and lower right corners are fixedly connected to the lane slab. The short-circuit support is perpendicular to the inverted U-shaped support and fixedly connects the arc support and the inverted U-shaped support. The arc support is provided with a prestressed device to provide internal prestress.

[0006] As a preferred solution, the arc-shaped support is composed of a plurality of arc-shaped steel plates fixedly connected, and the arc-shaped steel plates are provided with stiffening ribs.

[0007] As a preferred solution, the inverted U-shaped support includes two support columns, and a cross beam is provided between the top ends of the two support columns for fixed connection.

[0008] As a preferred solution, the support column is provided with an oblique support fixedly connected to the crossbeam.

[0009] As a preferred solution, a reinforcement support is provided inside the inverted U-shaped support to increase the overall rigidity.

[0010] As a preferred solution, the arc-shaped supports are provided with end supports fixedly connected to the lane slab.

[0011] As a preferred solution, the arc-shaped steel plates are provided with connecting plates for reinforcement connection, and the connecting plates include inner connecting plates, outer connecting plates and middle connecting plates for multi-position reinforcement connection.

[0012] As a preferred solution, the prestressing device is a jack, which is arranged on the arc-shaped support part, and has both ends fixedly connected to the arc-shaped steel plates to provide prestressing.

[0013] The beneficial effects of the present invention are: The present invention forms a stable spatial force system inside the ultra-large diameter tunnel during the construction of the frozen connecting channel through the design of a close fit between the arc-shaped support and the inner wall of the tunnel, combined with the anchoring effect of the inverted U-shaped support on the lane plate. The stiffening ribs on the back of the arc-shaped steel plate significantly improve the circumferential stiffness of the support, so that the horizontal frost heave deformation of the connecting channel is controlled within 30% of the design allowable value; the oblique support in the inverted U-shaped support works in conjunction with the internal reinforcement support to reduce the stress concentration factor of the key node by more than 60%. At the same time, the lower space of the inverted U-shaped support 2 can ensure that traffic and transportation in the tunnel are not interfered with by the support. The triple connecting plate structure ensures the reliability of force transmission at the arc-shaped steel plate joints, and cooperates with the variable angle arrangement of the short-circuit support to achieve uniform transmission of frost heave force to the main structure of the tunnel. The application of prestressed cross braces enables the support system to form an internal stress field that resists deformation in advance. At the same time, the structure's repeatable disassembly and assembly characteristics reduce the cost of single-channel support materials by 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein Figure 1 It is a schematic diagram of the axial structure of the present invention.

[0015] Figure 2 It is a schematic diagram of the partial structure of the arc support of the present invention.

[0016] Figure 3 It is a schematic diagram of the radial structure of the present invention.

[0017] The numbers in the figure are: 1. Arc support; 11. Arc steel plate; 12. Stiffening rib; 13. Inner connecting plate; 14. Outer connecting plate; 15. Middle connecting plate; 16. End support; 2. Inverted U-shaped support; 21. Support column; 22. Crossbeam; 23. Diagonal support; 24. Reinforced support; 3. Short-circuit support; 4. Cross brace; 5. Prestressed device. DETAILED DESCRIPTION

[0018] To illustrate the features of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example: See also Figures 1 to 3 An embodiment of the present invention provides a prestressed tunnel support for a frozen communication channel in an ultra-large diameter shield tunnel. For the construction of a frozen communication channel in a 15.2-meter diameter tunnel, the arc support 1 of the longitudinal support unit is assembled on-site using eleven sets of customized arc steel plates 11. A jack is set between the two top arc steel plates 11 as a prestressing device 5 to provide prestress for the arc support 1. The jack is set in the middle of the arc support 1, and the arc steel plates 11 are fixedly connected at both ends. Continuous trapezoidal stiffening ribs 12 are welded to the back of each arc steel plate 11 to form a rigid arch ring, the inner arc surface of which is in close contact with the tunnel lining. The end supports 16 set at the ends of the arc support 1 are connected to the lane plate to form a complete support loop. The vertical support column 21 of the inverted U-shaped support 2 is fixedly connected to the lane slab. A cross beam 22 is set on the top of the support column 21 and connected to the top of the arc-shaped support 1 through a high-strength pin to form a stable support. A cross stiffening plate is set in the support column 21 to enhance the bending resistance, and a bidirectional inclined oblique support 23 steel plate is installed at the beam-column node, which significantly improves the stability of the node domain. At the same time, the lower space of the inverted U-shaped support 2 can ensure that the passage and transportation in the tunnel are not interfered with by the support.

[0020] Furthermore, the curved steel plates 11 of this embodiment feature a triple-security connection structure: The curved steel plates 11 are secured at their joints using a multi-dimensional arrangement of inner connecting plates 13, outer connecting plates 14, and central connecting plates 15. High-strength bolts are tightened with a hydraulic torque wrench to create a secure connection. Three sets of short-circuit supports 3 are positioned on either side of the inverted U-shaped support 2, securing the waist of the curved support 1 and forming a three-dimensional truss system to resist frost heave forces. Cross braces 4 are installed between the units for dual-directional reinforcement, forming a complete support system.

[0021] In this example, when the freezing cycle system cooled the ground in the connecting channel area to -28°C, the support system effectively suppressed horizontal frost heave deformation, maintaining the curved surface of the arc support 1 intact and in place. The cross brace 4 formed a prestressed field, pre-emptively building internal stress to resist deformation. During the peak frost heave pressure phase, the synergistic effect of the diagonal supports 23 and the reinforced supports 24 significantly reduced stress concentration at the nodes. Monitoring during the dismantling phase revealed no plastic deformation at all connection nodes, and the bolt threads remained intact after the connecting plate was removed, verifying the repeatability of this support system.

[0022] The above embodiments and accompanying drawings are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the spirit and scope of the present invention do not depart from the spirit of the present invention and are intended to fall within the scope of the claims. Other related technical structures not fully disclosed in the present invention constitute prior art in the art.

Claims

1. A prestressed tunnel support for a frozen connecting channel of an ultra-large diameter shield tunnel, characterized by: It comprises a plurality of longitudinal support units and a transverse brace (4), wherein the transverse brace (4) fixedly connects two adjacent longitudinal support units; The longitudinal support unit comprises an arc support (1), an inverted U-shaped support (2) and a plurality of short-circuit supports (3). The position of the arc support (1) corresponds to the frozen connecting channel and is connected to the inner wall of the tunnel. The upper left and upper right corners of the inverted U-shaped support (2) are fixedly connected to the arc support (1), and the lower left and lower right corners are fixedly connected to the lane plate. The short-circuit supports (3) are perpendicular to the inverted U-shaped support (2) and are fixedly connected to the arc support (1) and the inverted U-shaped support (2). The arc support (1) is provided with a prestressing device (5) to provide internal prestressing.

2. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 1 is characterized by: The arc-shaped support (1) is composed of a plurality of arc-shaped steel plates (11) that are fixedly connected, and the arc-shaped steel plates (11) are provided with stiffening ribs (12).

3. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 1 is characterized in that: The inverted U-shaped support (2) comprises two support columns (21), and a crossbeam (22) is provided between the top ends of the two support columns (21) for fixed connection.

4. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 1 is characterized in that: The support column (21) is provided with an oblique support (23) fixedly connected to the crossbeam (22).

5. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 4 is characterized in that: A reinforcing support (24) is provided inside the inverted U-shaped support (2) to increase the overall rigidity.

6. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 1 is characterized in that: The arc-shaped support (1) is provided with an end support (16) for fixedly connecting the lane slab.

7. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 2 is characterized by: The arc-shaped steel plate (11) is provided with a connecting plate for reinforcement connection, and the connecting plate comprises an inner connecting plate (13), an outer connecting plate (14) and a middle connecting plate (15) for multi-position reinforcement connection.

8. The prestressed tunnel support for the frozen connecting channel of an ultra-large diameter shield tunnel according to claim 2 is characterized in that: The prestressing device (5) is a jack, which is arranged in the middle of the arc-shaped support (1), and has both ends fixedly connected to the arc-shaped steel plates (11) to provide prestressing force.

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