Counter-force frame for shield launching opening negative ring and construction method of counter-force frame

Abstract

The invention provides a counter-force frame for a shield launching opening negative ring and a construction method of the counter-force frame. The counter-force frame comprises a pi-shaped beam, a transverse beam and a transverse beam, the two stand columns are parallel to the plane where the pi-shaped beam is located, and the upper portion of each stand column is connected with the oblique beam on the corresponding side through a set of connecting pieces; the two sets of connecting pieces are correspondingly arranged between the two oblique beams and the stand columns on the corresponding sides respectively. Wherein each group of connecting pieces comprises a plurality of connecting pieces; the supporting assembly comprises two inclined struts and two groups of first horizontal struts; one ends of the two inclined struts are correspondingly connected with the middle parts of the two upright posts respectively; the two first horizontal supports are correspondingly and vertically arranged on the lower portions of the two stand columns respectively. Through the structural design of the counter-force frame, the counter-force frame is suitable for providing counter-force in the shield tunneling machine propelling process when the negative ring is a split ring, the counter-force frame can be installed and fixed without full-ring splicing of the negative ring, the using amount of negative ring materials is effectively reduced, time consumed for splicing and dismounting of the negative ring is reduced, and the construction efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a reaction frame for the negative ring of the shield tunneling initiation opening and its construction method. Background Technology

[0002] During the initial startup phase of a tunnel boring machine (TBM), the main unit of the TBM must be mounted on the launching frame, with a reaction frame positioned behind it to provide reaction force during the TBM's advancement. During the initial normal tunneling process, segments, known as negative rings, need to be installed inside the shield. These negative rings contact the reaction frame to transmit the reaction force during advancement. Once the TBM has advanced a specific distance, the negative rings and reaction frame must be removed.

[0003] Currently, the traditional tunneling method using full-ring negative rings and reaction frames results in a significant waste of negative ring material and a long time consumption during the assembly and disassembly of the negative rings.

[0004] In view of the shortcomings of the existing tunneling methods using full-ring negative rings and reaction frames, those skilled in the art have been searching for solutions.

[0005] Therefore, there is an urgent need to develop a new type of launching device to save on the use of negative ring material and solve the problem of extended launching time caused by the assembly and disassembly of the negative ring. Summary of the Invention

[0006] The purpose of this invention is to provide a reaction frame for the negative ring of a shield tunneling initiation opening and its construction method, which can save the amount of negative ring material used and reduce the time consumption for negative ring assembly and dismantling.

[0007] To solve the above-mentioned technical problems, the present invention provides a reaction frame for a shield tunneling starting opening negative ring, the reaction frame for a shield tunneling starting opening negative ring comprising:

[0008] A π-shaped beam includes: a horizontal beam and two symmetrically distributed inclined beams connected to it;

[0009] Two columns are distributed parallel to each other and parallel to the plane of the π-shaped beam. The upper part of each column is connected to the inclined beam on the corresponding side by a set of connectors.

[0010] Two sets of connectors are respectively installed between the two inclined beams and the corresponding columns; each set of connectors includes multiple connectors.

[0011] A support component includes: two diagonal braces and two sets of first horizontal braces; one end of each of the two diagonal braces is connected to the middle of one of the two columns respectively; the two sets of first horizontal braces are respectively vertically arranged at the lower part of the two columns.

[0012] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the support assembly further includes: a plurality of second horizontal braces, which are disposed between the arch bottom block (-11) located between the two columns and the inner lining wall of the station structure.

[0013] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the diagonal brace is made of double-section 900H steel.

[0014] Optionally, in the reaction frame for the shield tunneling initiation opening negative ring, the length of the connector is calculated based on the number of opening rings required for construction and the width of the opening negative ring.

[0015] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the support assembly further includes: two pre-embedded anchor plates, which are respectively pre-embedded in the station structure platform layer at a preset position, so as to be connected to the other end of the two diagonal braces respectively.

[0016] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the π-shaped beam is made of Q235 steel.

[0017] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the first horizontal brace and the connecting member are both steel pipes with an outer diameter of 406mm.

[0018] Optionally, in the reaction frame for the shield tunneling starting opening negative ring, the second horizontal brace is a steel pipe with an outer diameter of 530 mm.

[0019] The present invention also provides a construction method for a reaction frame for a shield tunneling starting opening negative ring, the construction method for the reaction frame for a shield tunneling starting opening negative ring includes:

[0020] S1. Based on the simulated force analysis of the tunnel boring machine's thrust and the reaction force system of the opening negative ring, and the number of rings and width of the opening negative ring required for on-site construction, design the various components of the reaction frame for the shield tunneling starting opening negative ring as described in any one of claims 1 to 8 to meet the requirements.

[0021] S2. Install the two columns and some support components of the reaction frame; wherein, the two columns are connected to the station structure and are symmetrically distributed along the tunnel centerline; one end of each of the two diagonal braces is connected to the middle of the two columns respectively, and the other end is connected to the station structure; one end of each of the two sets of first horizontal braces is vertically set at the lower part of the two columns respectively, and the other end abuts against the inner lining wall of the station structure respectively; several second horizontal braces are set between the arch bottom block (-11) located between the two columns and the inner lining wall of the station structure;

[0022] S3. The tunnel boring machine advances forward to excavate and assembles the negative ring. After the predetermined full ring of the negative ring is exposed at the tail brush, the π-shaped beam and two sets of connectors are installed. The π-beam body is erected on the open negative ring adjacent to the full ring and connected to the adjacent full ring. The two sets of connectors are respectively set between the two inclined beams of the π-shaped beam and the corresponding columns.

[0023] S4. Complete the installation of the reaction frame.

[0024] Optionally, in the construction method of the reaction frame for the shield tunneling initiation opening negative ring, before performing S2, the method further includes:

[0025] Two pre-embedded anchor plates are pre-embedded at predetermined positions in the station platform layer to support and fix the two diagonal braces respectively.

[0026] In the reaction frame and its construction method for the opening negative ring of a tunnel boring machine (TBM) provided by this invention, the reaction frame includes: a π-shaped beam, comprising: a crossbeam and two symmetrically distributed inclined beams connected to it; two columns, parallel to each other and parallel to the plane of the π-shaped beam, with the upper part of each column connected to the corresponding inclined beam via a set of connectors; two sets of connectors, respectively disposed between the two inclined beams and the corresponding columns; wherein each set of connectors includes multiple connectors; a support assembly, comprising: two inclined braces and two sets of first horizontal braces; one end of each of the two inclined braces is connected to the middle of the two columns; the two sets of first horizontal braces are respectively vertically disposed at the lower part of the two columns. Through the structural design of the reaction frame, it is suitable for providing reaction force during the TBM's propulsion process when the negative ring is an open ring. The installation and fixing of the reaction frame can be completed without full ring assembly, effectively saving the amount of negative ring material used, reducing the time consumed in negative ring assembly and dismantling, and improving construction efficiency. Attached Figure Description

[0027] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0028] Figure 1 This is a schematic diagram of the reaction frame structure in one embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the π-shaped beam in one embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram showing the relative positions of the π-shaped beam, the negative ring, and the column in one embodiment of the present invention;

[0031] Figure 4 This is a schematic cross-sectional view of the column in one embodiment of the present invention;

[0032] Figure 5a This is a front view of the reaction frame during construction application in one embodiment of the present invention;

[0033] Figure 5b This is a left view of the reaction frame during construction application in one embodiment of the present invention;

[0034] Figure 5c This is a top view of the reaction frame in construction application according to an embodiment of the present invention;

[0035] Figure 6a This is a top view of a pre-embedded anchor plate in one embodiment of the present invention;

[0036] Figure 6b This is a side elevation view of the pre-embedded anchor plate in one embodiment of the present invention;

[0037] Figure 6c This is a front elevation view of the pre-embedded anchor plate in one embodiment of the present invention.

[0038] In the picture:

[0039] 100-π type beam: 1-Horizontal beam; 2-Inclined beam;

[0040] 3-Columns;

[0041] 4-Connectors;

[0042] 200-Supporting components: 5-First horizontal brace; 6-Second horizontal brace; 7-Diagonal brace; 8-Embedded anchor plate. Detailed Implementation

[0043] The reaction frame for the shield tunneling initiation opening negative ring and its construction method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0044] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0045] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "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 the invention 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 the invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] Please refer to Figures 1 to 4 The reaction frame for the shield tunneling starting opening negative ring includes: a π-shaped beam 100, two sets of connectors, two columns 3, and a support assembly 200. The π-shaped beam 100 includes: a crossbeam 1 and two inclined beams 2 connected to it and symmetrically distributed. The two columns 3 are parallel to each other and parallel to the plane of the π-shaped beam 100. The upper part of each column 3 is connected to the inclined beam 2 on the corresponding side through a set of connectors. The two sets of connectors are respectively set between the two inclined beams 2 and the corresponding column 3. Each set of connectors includes multiple connectors 4. The support assembly 200 includes: two diagonal braces 7, two sets of first horizontal braces 5, and several second horizontal braces 6. One end of each of the two diagonal braces 7 is respectively connected to the middle of the two columns 3, and the two sets of first horizontal braces 5 are respectively vertically set at the lower part of the two columns 3.

[0049] The reaction frame structure of this invention is simple and easy to manufacture. Specifically, the reaction frame has relatively few components, usually welded together from several sections of steel and steel pipes. It does not require complex connectors or special materials. At the same time, the manufacturing process mainly involves basic processes such as cutting and welding, which are very mature in modern construction, easy to operate, and have controllable quality.

[0050] Furthermore, the reaction frame of the present invention is easy to install and disassemble, and can be reused. The reaction frame of the present invention only requires the π beam body to be connected to the steel column through the support component. With the negative ring segment in the open ring state, it can be installed and fixed without full ring assembly. After use, it can save the time of removing the negative ring segment and can be reused in other places.

[0051] Furthermore, the reaction frame of this invention has excellent stability. After the π-shaped beam is installed, longitudinal pressure is provided by the steel pipe supports and the tunnel boring machine's thrust. The symmetrical structure on both sides allows the π-shaped beam to remain stable without other fixing methods.

[0052] Furthermore, the reaction frame of the present invention has universal applicability. The form, installation, and fixing method of the reaction frame of the present invention can be applied to all shield tunneling starting opening negative rings, only requiring adjustments based on structural dimensions, negative ring segment dimensions, thrust adjustment π-shaped beams, connector dimensions, and material types.

[0053] Furthermore, the support assembly also includes a plurality of second horizontal braces 6, which are disposed between the structural gaps located between the lower parts of the two columns.

[0054] Please refer to Figure 1 In this embodiment, the diagonal brace 7 is made of double 900H-beams. Double 900H-beams refer to two H-beams, each approximately 900 mm high, connected back-to-back or side-by-side along their weak axis (usually parallel to the web) using welding or high-strength bolts to form a single integral cross-section. The length of the connector 4 is calculated based on the number of open rings and the width of the open negative ring required for construction.

[0055] like Figure 1 and Figure 5b As shown, there are 7 open rings (labeled 4-10). The total width of the stacked rings is obtained by adding the widths of all the open negative rings together. The length of the connector is determined based on this, which spans the space corresponding to the total width and connects the π-shaped beam to the column. This allows the reaction frame to abut against the full ring and the inner lining wall of the structure to provide reaction force during the advancement of the tunnel boring machine.

[0056] Please refer to Figures 5b to 6cThe support assembly further includes two pre-embedded anchor plates 8, which are respectively pre-embedded in the station structure platform layer at a predetermined position, to be connected to the other end of the two diagonal braces 7 respectively. It can be understood that the size of the pre-embedded anchor plates 8 is adapted to the maximum shear force and reaction force of the downward slope of the two diagonal braces 7 of the support assembly, so that the diagonal braces 7 can stably support the column 3.

[0057] Here, before the reaction frame is installed, anchor plates need to be pre-embedded in the bottom slab of the station platform layer. The anchor plates can be cast at the same time as the concrete of the bottom slab of the platform layer to support and fix the two diagonal braces 7.

[0058] In this embodiment, the π-shaped beam is preferably made of Q235 steel; to enhance structural stability and load-bearing capacity, the crossbeam 1 is preferably made of 350H steel with stiffening plates on both sides; the inclined beam 2 is preferably made of 350H steel with stiffening plates on both sides; the first horizontal brace 5 and the connector 4 are both steel pipes with an outer diameter of 406mm; the second horizontal brace 6 is a steel pipe with an outer diameter of 530mm; the column 3 is preferably a steel column with a cross-sectional dimension of 800mm×800mm.

[0059] Accordingly, this embodiment also provides a construction method for a reaction frame used in the negative ring of the shield tunneling initiation opening. See below for reference. Figures 1 to 6c This embodiment details the construction method of the reaction frame used for the negative ring of the shield tunneling initiation opening.

[0060] First, perform step S1, and conduct a simulated force analysis based on the tunnel boring machine's thrust and the reaction force system of the opening negative ring, as well as the number of rings and the width of the opening negative ring required for on-site construction. Design the various components of the reaction frame for the shield tunneling starting opening negative ring as described above to meet the requirements.

[0061] Specifically, based on calculations of the tunnel boring machine's thrust, and while meeting the material's inherent stress, deflection, and stability requirements, the steel plate thickness can be flexibly adjusted according to the reaction force. The steel plate thickness ranges from 1cm to 2cm. An open negative ring forms the space required for hoisting tunnel segments, mud buckets, and other materials during the tunnel boring machine's advancement. Based on the reserved distance between the column and the end shaft's inner lining wall, as well as the number and width of the open negative rings required for on-site construction, the length of the connecting piece between the π-beam body and the column is calculated to facilitate subsequent installation of the π-beam body. Connector 4 connects the π-beam body to the column, forming a stable overall structure. Simulated force analysis and calculations are performed based on the tunnel boring machine's thrust and the reaction force system of the open negative ring to design the material types and dimensions of each component of the open negative ring reaction frame, ensuring the stability of the reaction force system structure during tunnel boring machine excavation.

[0062] Next, step S2 is performed to install the two columns 3 and some support components of the positioning reaction frame; wherein, the two columns 3 are connected to the station structure and are symmetrically distributed along the tunnel centerline; one end of each of the two diagonal braces 7 is connected to the middle of the two columns 3 respectively, and the other end is connected to the station structure; one end of each of the two sets of first horizontal braces 5 is vertically set at the lower part of the two columns 3 respectively, and the other end abuts against the inner lining wall of the station structure; several second horizontal braces 6 are set between the arch bottom block (-11) located between the two columns and the inner lining wall of the station structure.

[0063] Specifically, the top of column 3 rests directly on the central slab structure of the station; the position of the steel column is determined based on the width of the negative ring.

[0064] Next, step S3 is executed, the tunnel boring machine advances forward to excavate, assembles the negative ring, and after the predetermined full ring negative ring is exposed at the tail brush, the π-shaped beam and two sets of connecting parts are installed; wherein, the π-beam body is erected on the open negative ring adjacent to the full ring negative ring and connected to the adjacent full ring negative ring; the two sets of connecting parts are respectively set between the two inclined beams 2 of the π-shaped beam and the corresponding columns 3.

[0065] In this embodiment, the first horizontal brace 5 between the column 3 and the station inner wall mainly functions to connect and transmit force, and to share the force generated by the hydraulic cylinders on both sides acting on the column. The second horizontal brace 6 between the arch base block-11 and the station inner wall mainly functions to connect and transmit force, and to bear the reaction force generated by the lower hydraulic cylinders.

[0066] Specifically, the first horizontal brace 5 is fixedly welded to the column 3; the second horizontal brace 6 is fixedly welded to the -11 segment with a 2cm steel plate; and the steel plate (as a capping plate) is first placed at the corresponding position between the second horizontal brace 6 and the inner wall of the station, and then fixedly welded.

[0067] Please refer to Figure 5b ,like Figure 5bAs shown, -10, -9, -8, -7, -6, -5, and -4 are all open negative rings, -3, -2, and -1 are full-ring negative rings, and -11 is the arch bottom block. In this embodiment, during the assembly of the negative rings, the open negative rings -10 → -9 → -8 → -7 are installed first. During or after this process, the arch bottom block -11 can be installed. It can be transported to the designated position by the double beam (the device for transporting tunnel segments inside the tunnel boring machine) and connected to the open negative ring -10 by bolts. Subsequently, the negative rings numbered -6, -5, -4, -3, -2, and -1 are assembled in sequence. Generally, negative rings are full-ring circular shapes. In this invention, the space between the open negative rings -4 and -10 is used to accommodate the hoisting of tunnel segments, mud buckets, and other materials during the tunneling process. The reaction system of this invention can complete the installation and fixation of the reaction frame without the need for full-ring assembly of the negative ring, effectively saving the amount of negative ring material used, reducing the time spent on negative ring assembly and disassembly, and improving construction efficiency.

[0068] The arch bottom block -11 ring has only one segment installed to transfer force to the horizontal brace 6. Because the station platform level in the current embodiment is recessed relative to the middle slab, placing a segment can shorten the length of the horizontal brace 6, resulting in better force distribution. The open negative rings are -10 to -4 rings, each with only 3 segments assembled. The -3 to -1 rings are composed of 6 segments assembled into a circle, i.e., full ring segments. They are all steel negative ring segments, temporary. The negative ring segments will be removed when the friction between the tunnel concrete segments and the soil can resist the shield reaction force.

[0069] Once the π-shaped beam is installed, it relies on the support components and the thrust of the tunnel boring machine to provide longitudinal pressure. The symmetrical structure of the π-shaped beam on both sides allows it to remain stable without any other fixing methods.

[0070] Next, proceed to step S4 to complete the construction of the reaction frame.

[0071] Furthermore, before executing S2, the following steps are included: pre-embedding two anchor plates 8 at predetermined positions in the station structure platform layer to respectively support and fix the two diagonal braces 7. Here, the required anchor plate size and reinforcement are determined based on the maximum shear force and reaction force at the lower slope of the diagonal brace 7.

[0072] The force transmission process of the reaction frame of the present invention is briefly described by component number as follows: The reaction frame system of the present invention includes components 1 to 7. Before the tunnel boring machine advances to the -1 ring, components 1, 2, and 4 are not installed. During this process, the middle and lower hydraulic cylinders are mainly used to transmit force to components 5, 6, and 7 through the column 3. When the tail brush of the shield is separated from the -3 ring, the frame 1, 2, and 4 can be installed. After that, all the propulsion hydraulic cylinders can be used. The entire reaction system can then transmit force to the column 3 through 1, 2, 4 and the steel pipe segments, and then transmit force to components 5, 6, 7 and the station middle plate structure through the column 3.

[0073] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0074] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0075] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A reaction frame for the negative ring of a shield tunneling initiation opening, characterized in that, include: A π-shaped beam includes: a horizontal beam (1) and two inclined beams (2) connected to it and symmetrically distributed. Two columns (3) are distributed in parallel to each other and are parallel to the plane of the π-shaped beam. The upper part of each column (3) is connected to the inclined beam (2) on the corresponding side through a set of connectors. Two sets of connectors are respectively installed between the two inclined beams (2) and the corresponding columns (3); each set of connectors includes multiple connectors (4). A support component includes: two diagonal braces (7) and two sets of first horizontal braces (5); one end of the two diagonal braces (7) is connected to the middle of the two columns (3) respectively; the two sets of first horizontal braces (5) are respectively vertically set at the lower part of the two columns (3).

2. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The support assembly also includes: a plurality of second horizontal braces (6) disposed between the arch base block (-11) located between the two columns and the inner lining wall of the station structure.

3. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The diagonal brace (7) is made of double-section 900H steel.

4. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The length of the connector (4) is calculated based on the number of open rings and the width of the open negative ring required for construction.

5. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The support assembly also includes two pre-embedded anchor plates (8), which are pre-embedded in the station structure platform layer at a preset position, so as to be connected to the other end of the two diagonal braces (7) respectively.

6. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The π-shaped beam is made of Q235 steel.

7. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The first horizontal brace (5) and the connector (4) are both steel pipes with an outer diameter of 406 mm.

8. The reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, The second horizontal support (6) is a steel pipe with an outer diameter of 530 mm.

9. A construction method for a reaction frame for a shield tunneling initiation opening negative ring as described in any one of claims 1 to 8, characterized in that, include: S1. Based on the simulated force analysis of the tunnel boring machine's thrust and the reaction force system of the opening negative ring, and the number of rings and width of the opening negative ring required for on-site construction, design the various components of the reaction frame for the shield tunneling starting opening negative ring as described in any one of claims 1 to 8 to meet the requirements. S2. Install the two columns (3) of the reaction frame and some supporting components; wherein, the two columns (3) are connected to the station structure and are symmetrically distributed along the tunnel centerline; one end of the two diagonal braces (7) is connected to the middle of the two columns (3) respectively, and the other end is connected to the station structure; one end of the two sets of first horizontal braces (5) is respectively vertically set at the lower part of the two columns (3), and the other end is respectively abutted against the inner wall of the station structure; several second horizontal braces (6) are set between the arch bottom block (-11) located between the two columns and the inner wall of the station structure; S3. The tunnel boring machine advances forward to excavate and assembles the negative ring. After the predetermined full ring negative ring is exposed at the tail of the shield, the π-shaped beam and two sets of connectors are installed. The π-beam body is erected on the open negative ring adjacent to the full ring negative ring and connected to the adjacent full ring negative ring. The two sets of connectors are respectively set between the two inclined beams (2) of the π-shaped beam and the corresponding column (3). S4. Complete the installation of the reaction frame.

10. The construction method of the reaction frame for the negative ring of the shield tunneling initiation opening as described in claim 1, characterized in that, Before executing S2, the following are also included: Two pre-embedded anchor plates (8) are pre-embedded at predetermined positions in the station structure platform layer to support and fix the two diagonal braces (7) respectively.

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