A starting cavern for assisting small-section TBM support shoes and a construction method thereof

Abstract

An auxiliary small-section TBM support shoe starting chamber and a construction method thereof belong to the technical field of tunnel construction, comprising a city gate type starting chamber body formed by surrounding rock of the starting chamber, the starting chamber body comprising an integrally formed straight wall and a top arch, the upper end of the top arch being a semicircular structure, the distance between the two inner walls of the lower end gradually decreasing, the inner wall between the upper end and the lower end of the top arch forming an arc-shaped support surface, the distance from each point on the arc-shaped support surface to the center of the top arch being equal, and the inner arc surface of the arc-shaped support surface fitting the circular arc-shaped support surface of the TBM shield body and the TBM support shoe. The construction method comprises eight steps of bedrock surface treatment, anchoring mortar anchor rod, steel mesh hanging net, formwork support, concrete injection construction, surface repair and maintenance, formwork removal and bottom plate pouring. The starting chamber structure is integrally formed, the chamber support system and the auxiliary TBM support shoe structure do not need to be constructed separately, the construction process and difficulty are reduced, the construction time can be effectively shortened, and the TBM starting efficiency is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically the field of starting tunnel construction technology for small-section tunnels, and particularly relates to a starting tunnel with an auxiliary small-section TBM support shoe and its construction method. Background Technology

[0002] With the rapid development of domestic pumped storage and mining industries and the need for mechanization transformation, hard rock tunnel boring machines (TBMs), as a safe, efficient, and advanced non-blasting underground engineering construction technology, have been actively promoted and applied. Pilot tunnel launching is currently the safest and most mature TBM launching process. A launching chamber is often used before TBM tunnel excavation to assist in the TBM's step-by-step launching.

[0003] In existing technologies, the construction of TBM launching tunnels typically involves blasting to excavate a portal-shaped tunnel. Later stages generally involve integral casting of a circular full-section concrete structure or, after the portal-shaped support is in place, adding an additional curved concrete structure on both sides of the support shoe. However, this approach presents challenges related to curved surfaces, custom-made and irregularly shaped formwork, difficulties in formwork support, and challenges in concrete pouring. Furthermore, it presents construction bottlenecks such as complex procedures and difficulties in quality control. This not only results in difficult construction, high investment, and low efficiency but also hinders the realization of the TBM's high-efficiency launching tunnel construction advantages. Therefore, technical solutions are needed for the construction of the launching tunnel structure that supports the TBM support shoe. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a starting cavern for a small-section TBM support shoe and its construction method, so as to solve the technical problems of complex procedures, high construction difficulty, large investment, difficulty in quality control and low construction efficiency of the TBM starting cavern in the prior art.

[0005] To achieve the above and other related objectives, the present invention provides a launching chamber for an auxiliary small-section TBM support boot, comprising a portal-shaped launching chamber body formed by the surrounding rock of the launching chamber. The launching chamber body includes an integrally formed straight wall and a top arch. The upper end of the top arch has a semi-circular structure, and the distance between the two inner walls at the lower end gradually decreases. The inner wall between the upper and lower ends of the top arch forms an arc-shaped support surface. The distance from each point on the arc-shaped support surface to the center of the top arch is equal. The inner arc surface of the arc-shaped support surface is fitted with the arc-shaped support surface of the TBM shield and the TBM support boot. A launching chamber floor plate is provided between the straight walls, and a stepping track and a stepping trolley are provided on the launching chamber floor plate.

[0006] Preferably, in any of the above embodiments, the distance between the bottom outer wall of the arch and the straight wall is 180–220 mm.

[0007] Preferably, in any of the above embodiments, the straight wall and the arch both include a sealing layer on the base surface of the starting cavern formed by spraying onto the surrounding rock of the starting cavern.

[0008] Preferably, in any of the above embodiments, the top arch further includes a starting cavern structural layer sprayed onto the sealing layer of the starting cavern base surface. The starting cavern structural layer includes a skeleton composed of mortar anchors, connecting bars and steel mesh, and concrete integrally sprayed based on the skeleton.

[0009] A construction method for an initial tunnel using an auxiliary small-section TBM support shoe includes the following steps: S1. Bedrock surface treatment: The required cross-sectional dimensions of the starting cavern are excavated according to the design requirements using the blasting method. The two side walls at the bottom of the top arch are narrowed inward by 200mm to form a reserved space. Then, after marking the thickness of the sprayed concrete, the surrounding rock of the starting cavern is sprayed to form a sealing layer on the bedrock of the starting cavern. S2. Anchoring mortar anchors: After the initial tunnel foundation sealing layer is completed by spraying concrete, the mortar anchors are measured and positioned on the top arch. Holes are drilled in the tunnel wall at the corresponding positions to the design depth. The mortar anchors are anchored to the specified exposed length by grouting first and then installing the mortar anchors. The mortar anchors are all arranged perpendicular to the tunnel wall and maintain the same cross section in the circumferential direction, and are parallel to the tunnel axis in the longitudinal direction. S3. Reinforcing mesh installation: After the mortar anchor is anchored in place, connecting bars are welded along the tunnel axis at the designated position of the exposed part of the mortar anchor. Then, the reinforcing mesh is laid, and adjacent reinforcing meshes are overlapped and welded to the mortar anchor and connecting bars for fixation. S4. Template support: Lay out the template according to the reserved space, and determine the template width according to the spray coating thickness. Two wooden templates are symmetrically arranged at the bottom of the top arch as the bottom templates. The wooden templates are supported by the bottom template support structure. S5. Concrete spraying construction: After the formwork support is completed, concrete spraying construction is carried out on the top arch to form the initial tunnel structure layer. The TBM support shoe and TBM shield body are fitted in the initial tunnel structure layer to form an arc-shaped support surface structure. S6. Finishing and curing: After the concrete spraying is completed and before the concrete sets, use a scraper to fit and finish the surface of the TBM support shoe. After finishing, water should be sprayed for curing in time. S7. Formwork Removal: After the sprayed concrete has cured to the specified strength, the formwork shall be removed; S8. Base Slab Casting: After the formwork is removed, the design elevation points of the base slab surface are measured and laid out on both sides of the straight wall. Then, concrete is poured to the designated elevation points. After surface finishing and curing, the stepping track and stepping trolley are installed.

[0010] In any of the above schemes, it is preferred that, in S2, the spacing between any two adjacent mortar anchors in the tunnel axis direction is 800-1200mm, and in the direction perpendicular to the tunnel axis direction, any two adjacent mortar anchors are arranged at 15° along the circumferential direction of the top arch.

[0011] In any of the above schemes, it is preferred that, in S2, the exposed length of the mortar anchor rod in the upper semi-circular structural section is 480-520 mm.

[0012] In any of the above embodiments, it is preferred that, in S3, the connecting bar is located 320-380mm from the exposed part of the mortar anchor rod at the sealing layer of the starting tunnel base, and the overlap length between two adjacent steel meshes is not less than 150mm.

[0013] In the above-mentioned scheme, it is preferred that, in S5, during the concrete spraying construction, the exposed mortar anchor rods are marked with red paint every 50mm for use in determining the thickness of the concrete spraying construction.

[0014] In any of the above schemes, it is preferred that in S7, the thickness of the base plate is greater than 200mm and the slope is 0°.

[0015] As described above, the starting chamber of the auxiliary small-section TBM support shoe and its construction method of the present invention have the following beneficial effects: 1. In this invention, the spatial layout of the starting tunnel structure is optimized so that the structural surface of the starting tunnel is more closely fitted to the TBM support shoe surface in order to provide sufficient force for the TBM stepping and to reserve operating space for construction personnel to start, debug and maintain the TBM. 2. In this invention, the construction difficulty of the initial tunnel structure is reduced, and there is no need to customize templates or set up complex template support systems, which helps to save costs. At the same time, the construction of the initial tunnel structure has fewer procedures, is simple to operate, and has controllable quality. 3. In this invention, the efficiency of the initial tunnel structure forming is improved. Compared with the existing tunnel structure construction methods, the initial tunnel structure is formed as a whole, eliminating the need to construct the tunnel support system and auxiliary TBM support shoe structure separately. This greatly reduces the construction process and difficulty, effectively shortens the construction time, and significantly improves the efficiency of TBM initial formation. Attached Figure Description

[0016] Figure 1 The diagram shows a cross-sectional view of the initial tunnel structure. Figure 2 The diagram shows a plan view of the support structure of the initial tunnel. Figure 3 The diagram shows a cross-sectional view of the support structure of the starting tunnel. Figure 4 The diagram shows the sealed sprayed concrete section of the initial tunnel. Figure 5 The diagram shows a cross-sectional schematic of the steel reinforcement cage system for the initial tunnel support. Figure 6 The diagram shows a cross-sectional view of the initial tunnel support sprayed concrete and support system. Figure 7 This is a schematic diagram of the cross-section of the floor slab of the starting tunnel. Figure 8 This is a schematic diagram of the steel mesh used in the initial tunnel structure.

[0017] Component designation explanation 1-Surrounding rock of the starting chamber; 2-Starting chamber body; 201-Starting chamber base sealing layer; 202-Mortar anchor; 203-Connecting bar; 204-Reinforcing mesh; 205-Structural layer of the starting chamber; 206-Straight wall; 207-Top arch; 3-TBM support shoe; 4-TBM shield; 5-Starting chamber floor slab; 6-Stepping track; 7-Stepping trolley; 8-Wooden formwork; 9-Bottom formwork support structure. Detailed Implementation

[0018] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0019] Please see Figures 1 to 8 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0020] Please see Figure 1-8 Example 1

[0021] In the existing technology, the starting chamber structure is a city gate shape. Without treatment, when the TBM uses the support shoe for stepping start, the contact area between the support shoe surface and the original side wall of the starting chamber structure is too small, which cannot provide sufficient force for its stepping and starting. Therefore, in this embodiment, the starting chamber structure is designed as a half-section structure and an arc-shaped support surface, and the support structure and auxiliary support structure are combined into one construction. This can not only ensure the safety of the starting chamber, but also meet the needs of the TBM support shoe (3) stepping, and can be constructed in one go with convenient construction, and can provide maintenance space for subsequent TBM starting. Specifically: A launching chamber for an auxiliary small-section TBM support boot includes a gate-shaped launching chamber body (2) formed by the surrounding rock (1) of the launching chamber. The launching chamber body (2) includes an integrally formed straight wall (206) and a top arch (207). The top arch (207) includes an upper end and a lower end with equal radii, both centered at the same point, and formed in one piece. The upper end of the top arch (207) is a semi-circular structure, and the distance between the two inner walls at the lower end gradually decreases. The inner wall between the upper and lower ends of the top arch (207) forms an arc-shaped support surface. The distance from each point on the arc-shaped support surface to the center of the top arch (207) is equal. The net cross-sectional diameter of the top arch (207) is larger than the effective diameter of the TBM shield (4). The arc-shaped support surface is a circular arc-shaped concrete structure surface that is adapted to the orientation, surface fitting, and effective support distance of the launching chamber and the TBM.

[0022] A starting chamber floor slab (5) is provided between the straight walls (206), and a stepping track (6) and a stepping trolley (7) are provided on the starting chamber floor slab (5).

[0023] In order to provide support for the top arch (207) and reserve space for TBM auxiliary operation, the bottom outer wall of the top arch (207) is narrowed inward in this embodiment, that is, the distance between the outer wall of the top arch (207) and the straight wall (206) is set to 200mm.

[0024] Of course, the distance between the outer wall of the top arch (207) and the straight wall (206) is not limited to 200mm. It can be adjusted according to the actual working conditions. For example, the distance between the outer wall of the top arch (207) and the straight wall (206) is 180-220mm.

[0025] In this embodiment, the top arch (207) has a cross-sectional width of 3830mm and a length of 8000mm; the TBM shield (4) has a cross-sectional width of 3530mm and a length of 7000mm.

[0026] In this embodiment, the main construction materials used for the starting cavern structure of the auxiliary small section TBM support shoe (3) are Φ25mm steel bars, Φ6mm steel mesh (204), C30 shotcrete, M30 mortar, C25 concrete, 15mm thick wooden formwork (8), Φ48×3.6mm steel frame pipe, and 80×60mm square timber.

[0027] As a further description of the above embodiments, both the straight wall (206) and the arch (207) include a sealing layer (201) of the starting cavern base surface formed by spraying onto the surrounding rock (1) of the starting cavern.

[0028] As a further description of the above embodiment, the top arch (207) also includes an initial cavern structural layer (205) sprayed onto the initial cavern base sealing layer (201). The initial cavern structural layer (205) includes a skeleton composed of mortar anchors (202), connecting bars (203), and steel mesh (204), and integrally sprayed concrete based on the skeleton. Specifically: First, a skeleton system is constructed, that is, mortar anchors (202) are evenly arranged in both directions parallel to and perpendicular to the tunnel axis. One end is inserted into the surrounding rock (1) of the starting cavern, and the other end is exposed. The distance from the exposed end to the center of the top arch (207) is equal. Then, the connecting bar (203) is welded and fixed along the tunnel axis at the same distance from the exposed end of the mortar anchor (202) to the sealing layer (201) of the starting cavern base. Then, the steel mesh (204) is installed. The steel mesh (204) is welded and fixed to the mortar anchor (202) and the connecting bar (203), and the steel mesh (204) overlaps with each other. The overlap is reinforced by welding.

[0029] Then, after setting up formwork support at the bottom of the skeleton system, concrete is sprayed onto the formwork system to form the initial cavern structure layer (205).

[0030] In summary, in this embodiment, the initial tunnel structure is connected by a steel frame and shotcrete to form an integral whole, and is supported by a structural form. While ensuring the structural stability and strength, the construction is more convenient and simple, and the operating space is larger. Example 2

[0031] The construction method for the starting chamber using a small-section TBM support shoe includes the following steps: S1. Bedrock treatment: The required cross-sectional dimensions of the starting cavern were excavated using blasting according to the design requirements. The bottom two side walls of the top arch (207) were narrowed inward by 200mm to assist in the support of the subsequent cavern structure, and space was reserved for TBM auxiliary operation. After measuring the cavern cross-section, an operating frame was erected using a Φ48×3.6mm steel pipe frame. Then, a 50mm shotcrete thickness was marked on the cavern wall with marker nails, and C30 shotcrete was sprayed onto the surrounding rock (1) of the starting cavern to form a sealing layer (201) on the base surface of the starting cavern. The initial cavern base sealing layer (201) of the top arch (207) includes an upper semi-circular structure and a lower vertical sidewall formed in one piece. The lower vertical sidewall narrows inward by 200mm and then connects to the initial cavern base sealing layer (201) of the straight wall (206) section.

[0032] Before concrete spraying, high-pressure air is used to clean the base surface of the starting tunnel wall to remove debris such as stone chips and stone powder, as well as accumulated water, before sealing the base surface of the surrounding rock.

[0033] S2. Anchoring mortar anchors (202): After the initial tunnel base sealing layer (201) is sprayed and sealed, the mortar anchors (202) are measured and positioned on the top arch (207). Holes are drilled in the tunnel wall to 2000mm at the corresponding positions. The mortar anchors (202) are anchored to the specified exposed length by grouting first and then installing the mortar anchors (202). The mortar anchors (202) are all arranged perpendicular to the tunnel wall and maintain the same cross section in the circumferential direction, and are parallel to the tunnel axis in the longitudinal direction. The principles for measuring and positioning mortar anchor bolts (202) are as follows: The mortar anchor bolts (202) are arranged at 15° circumferentially around the top of the semi-circular structure section at the upper end of the top arch (207), perpendicular to the tunnel axis. Arranged at 450mm intervals on the vertical sidewall sections at the lower end of the top arch (207); The upper semi-circular structural section and the lower vertical sidewall section are arranged at intervals of 1000mm along the tunnel axis.

[0034] Among them, the mortar anchor (202) uses Φ25mm steel bars and is 2500mm long. The exposed length of the mortar anchor (202) on the upper semi-circular structural section of the top arch (207) is 500mm. The exposed length of the mortar anchor (202) on the lower vertical side wall section of the top arch (207) is adjusted appropriately according to the fitting distance so that the distance from the end of the exposed end of the mortar anchor (202) to the center of the top arch (207) is equal. The mortar anchor (202) was made by drilling holes in the tunnel wall using a YT-28 pneumatic rock drill, and then by grouting first and then inserting the rod to ensure that the mortar anchor (202) was anchored in place.

[0035] S3. Reinforcing mesh (204) installation: After the mortar anchor (202) is anchored in place, a connecting bar (203) is welded along the tunnel axis at 350mm of the exposed part of the mortar anchor (202). Then, a single layer of reinforcing mesh (204) is laid. Adjacent reinforcing meshes (204) are interlocked and the reinforcing mesh (204) is welded and fixed to the mortar anchor (202) and the connecting bar (203). Among them, the connecting bar (203) is a Φ25mm steel bar with a length of 8000mm; The specifications of the steel mesh (204) are: Φ6@150×150mm, size 1350mm×1350mm, and the overlap between adjacent steel mesh (204) is reinforced by welding; The overlap length between adjacent steel mesh (204) shall not be less than 150mm.

[0036] S4. Template support: The template is laid out according to the reserved space position, and the width of the template is determined according to the spraying thickness. Two wooden templates (8) are symmetrically arranged at the bottom of the top arch (207) as the bottom template. During the fixing process, the wooden template (8) should be perpendicular to the hole wall and parallel to the hole axis in the longitudinal direction. The wooden template (8) is supported by the bottom formwork support structure (9) below. Among them, the wooden formwork (8) uses boards with a thickness of 15mm, a length of 8000mm, and a width of 500mm; The wooden formwork (8) uses 60mm×80mm square timber as joists and Φ48×3.6mm steel frame pipes as supports and reinforcement; The bottom formwork support structure (9) is existing technology. As can be known by those skilled in the art based on existing technology, the structure and working method of the bottom formwork support structure (9) will not be further described in this embodiment.

[0037] S5. Concrete spraying construction: After the formwork support is completed, concrete spraying construction is carried out on the top arch (207) to form the starting cavern structure layer (205). The starting cavern structure layer (205) is fitted with TBM support boots (3) and TBM shield (4) in an arc-shaped support surface structure. Before spraying, high-pressure air should be used to clean the dust, mud and other stains on the surface of the structural compartment; after the concrete spraying machine is installed and debugged, a spraying test should be carried out to ensure that the equipment is normal before the initial tunnel structure spraying construction can be carried out. The sprayed concrete grade is C30, and the spraying thickness is 450mm; During the spraying operation, the material is continuously supplied and fine-tuned according to the material to keep the working air pressure stable at 0.25-0.5MPa, ensuring that the sprayed concrete is dense and reducing rebound. Reduce the distance between the nozzle and the surface to be sprayed appropriately, keeping it within 600-1200mm as much as possible. Adjust the spray angle in real time during the process to avoid the nozzle pointing directly at the steel bars. The nozzle and the surface to be sprayed should maintain a 90° angle. At the same time, the shotcrete should be applied from bottom to top, in sections, pieces, and layers. The length of each section should be controlled below 6000mm, the process for each piece should be the tunnel wall first and then the tunnel top, and the thickness of each layer should be controlled at 50mm. The thickness control method is as follows: the exposed mortar anchor rods (202) should be marked with red paint every 50mm for the shotcrete thickness measurement. When spraying in layers, the next layer is applied after the previous layer of concrete has fully set.

[0038] S6. Finishing and curing: After the concrete spraying is completed, before the concrete sets, a 2000mm long rectangular aluminum alloy scraper is used to fit and finish the TBM support boot (3) surface area to make it fit the support boot surface better. The remaining parts are simply leveled. After the finishing is completed, water is sprayed for curing in time.

[0039] S7. Formwork Removal: After the sprayed concrete has cured to the specified strength, the formwork shall be removed; specifically: After the shotcrete in the initial cavern structural layer (205) has been cured and its strength increased to a sufficient level to support its own weight and possible external loads, the formwork can be removed only when the structure is free from deformation and settlement. Specifically, the formwork can be removed only after the strength is greater than 75%, and the actual strength is based on the test results of test blocks cured under the same conditions.

[0040] S8. Bottom slab pouring: After the formwork is removed, the design elevation points of the bottom slab surface are measured and laid out on both sides of the straight wall (206). Then, C25 concrete is used for pouring to meet the design requirements of the slope and elevation of the bottom slab (5) of the starting tunnel. After the pouring is completed, the surface is finished and cured. Then, the stepping track (6) and stepping trolley (7) are installed to ensure that the stepping track (6) and stepping trolley (7) are installed normally.

[0041] The base slab has a thickness of 600mm and a slope of 0°.

[0042] As a further description of the above embodiment, in S2, the spacing between any two adjacent mortar anchors (202) in the tunnel axis direction is not limited to 1000mm, and can be adjusted accordingly according to the working conditions, such as 800 to 1200mm between any two adjacent mortar anchors (202).

[0043] As a further description of the above embodiment, in S2, the exposed length of the mortar anchor rod (202) in the upper semi-circular structural section is not limited to 500mm, and can be adjusted accordingly according to the construction situation, such as within the range of 480 to 520mm.

[0044] As a further description of the above embodiment, in S3, the connecting bar (203) is set at a distance of 350mm from the exposed part of the mortar anchor rod (202) from the sealing layer (201) of the starting cavern base, but not limited to 350mm. It can be adjusted accordingly according to the actual working conditions, such as within the range of 320 to 380mm.

[0045] As a further description of the above embodiment, in S7, the thickness of the base plate is not limited to 600mm, and can be adjusted accordingly according to the actual working conditions, as long as the thickness of the base plate is greater than 200mm.

[0046] In summary, this invention, by integrally forming the launching chamber structure, eliminates the need for separate construction of the chamber support system and auxiliary TBM support structure, significantly reducing construction procedures and difficulties, effectively shortening construction time, and greatly improving TBM launching efficiency. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A starting chamber for an auxiliary small-section TBM support shoe, comprising a portal-shaped starting chamber body (2) formed by the surrounding rock (1) of the starting chamber, characterized in that: The launching chamber body (2) includes an integrally formed straight wall (206) and a top arch (207). The upper end of the top arch (207) is a semi-circular structure, and the distance between the two inner walls at the lower end gradually decreases. The inner wall between the upper and lower ends of the top arch (207) forms an arc-shaped support surface. The distance from each point on the arc-shaped support surface to the center of the top arch (207) is equal. The inner arc surface of the arc-shaped support surface fits the arc-shaped support surface of the TBM shield (4) and the TBM support shoe (3). The launching chamber bottom plate (5) is provided between the straight walls (206). The launching chamber bottom plate (5) is provided with a stepping track (6) and a stepping trolley (7).

2. The launching chamber of the auxiliary small-section TBM support shoe according to claim 1, characterized in that: The distance between the bottom outer wall of the top arch (207) and the straight wall (206) is 180-220mm.

3. The launching chamber of the auxiliary small-section TBM support shoe according to claim 1, characterized in that: The straight wall (206) and the arch (207) both include a sealing layer (201) of the starting cavern base surface formed by spraying onto the surrounding rock (1) of the starting cavern.

4. The launching chamber of the auxiliary small-section TBM support shoe according to claim 1, characterized in that: The top arch (207) also includes a starting cavern structural layer (205) sprayed onto the sealing layer (201) of the starting cavern base surface. The starting cavern structural layer (205) includes a skeleton composed of mortar anchors (202), connecting bars (203) and steel mesh (204) and concrete integrally sprayed based on the skeleton.

5. A construction method for an initial tunnel using an auxiliary small-section TBM support shoe, characterized in that, Includes the following steps: S1. Bedrock surface treatment: The required cross-sectional dimensions of the starting cavern are excavated according to the design requirements by blasting. The bottom two side walls of the top arch (207) are narrowed inward by 200mm to form a reserved space. Then, the thickness of the sprayed concrete is marked and sprayed onto the surrounding rock (1) of the starting cavern to form the sealing layer (201) of the starting cavern base surface. S2. Anchoring mortar anchors (202): After the initial tunnel base sealing layer (201) is sprayed and sealed, the mortar anchors (202) are measured and positioned on the top arch (207). Holes are drilled in the tunnel wall at the corresponding positions to the design depth. Then the mortar anchors (202) are anchored to the specified exposed length. The mortar anchors (202) are all arranged perpendicular to the tunnel wall and maintain the same cross section in the circumferential direction and are parallel to the tunnel axis in the longitudinal direction. S3. Reinforcing mesh (204) installation: After the mortar anchor (202) is anchored in place, the connecting bar (203) is welded along the tunnel axis at the designated position of the exposed part of the mortar anchor (202), and then the reinforcing mesh (204) is laid. The adjacent reinforcing meshes (204) are interlocked and the reinforcing meshes (204) are welded and fixed to the mortar anchor (202) and the connecting bar (203); S4. Template support: The template is laid out according to the reserved space position, and the width of the template is determined according to the spraying thickness. Two wooden templates (8) are symmetrically arranged at the bottom of the top arch (207). The wooden templates (8) are supported by the bottom formwork support structure (9) below. S5. Concrete spraying construction: After the formwork support is completed, concrete spraying construction is carried out on the top arch (207) to form the starting cavern structure layer (205). The inner surface of the starting cavern structure layer (205) is fitted with TBM support boots (3) and TBM shield (4) to form an arc-shaped support surface structure. S6. Finishing and curing: After the concrete spraying is completed, before the concrete sets, use a scraper to fit and finish the TBM support shoe (3) within the range. After finishing the surface, water should be sprayed for curing in time. S7. Formwork Removal: After the sprayed concrete has cured to the specified strength, the formwork shall be removed; S8. Base plate pouring: After the formwork is removed, the design elevation points of the base plate surface are measured and laid out on both sides of the straight wall (206). Then, concrete is poured to the designated elevation points. After surface finishing and curing, the stepping track and stepping trolley are installed.

6. The construction method for the starting chamber of the auxiliary small-section TBM support shoe according to claim 5, characterized in that: In S2, the spacing between any two adjacent mortar anchors (202) in the tunnel axis direction is 800-1200mm, and in the direction perpendicular to the tunnel axis direction, any two adjacent mortar anchors (202) are arranged circumferentially at 15° along the top arch (207).

7. The construction method for the starting chamber of the auxiliary small-section TBM support shoe according to claim 5, characterized in that: In S2, the exposed length of the mortar anchor rod (202) in the upper semi-circular structural section is 480-520 mm.

8. The construction method for the starting chamber of the auxiliary small-section TBM support shoe according to claim 5, characterized in that: In S3, the connecting bar (203) is set at a distance of 320-380mm from the exposed part of the mortar anchor (202) from the sealing layer (201) of the base surface of the starting cavern, and the overlap length between two adjacent steel meshes (204) is not less than 150mm.

9. The construction method for the starting chamber of the auxiliary small-section TBM support shoe according to claim 5, characterized in that: In S5, during the concrete spraying construction, the exposed mortar anchor rods (202) are marked with red paint every 50mm for use in determining the thickness of the concrete spraying construction.

10. The construction method for the starting chamber of the auxiliary small-section TBM support shoe according to claim 5, characterized in that: In S8, the thickness of the base plate is greater than 200mm and the slope is 0°.

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