A method for starting construction of a shield in a narrow space

Abstract

The application discloses a kind of narrow space under shield split originating construction method, in combination with engineering actual situation, originating end reinforcement, tooling assembly and shield machine assembly are carried out before construction.The hole door is broken and sealed, negative ring segment assembly and whole machine debugging are carried out when originating.The split originating mode is used, the outer layer reinforcement is removed first, and then the shield tail backfill grouting is carried out.The originating well length is less than the whole machine length of shield machine, and the originating end reinforcement, pile drilling sampling inspection reinforcement effect in hole opening range and three protection measures of face shotcrete protective layer are implemented by construction method improvement and construction step sequence adjustment to prevent soil collapse in originating stage.

Description

Technical Field

[0001] This invention relates to a subway construction technology, and more particularly to a method for the separate launching of a shield tunnel in a confined space. Background Technology

[0002] The shield tunneling start is the process by which the shield machine moves from the reinforced soil near the working shaft into the undisturbed soil section.

[0003] When a tunnel boring machine (TBM) is launched, the conventional method is to lower the TBM and the subsequent trolleys into the shaft and connect them before starting the excavation. The excavated soil is then transported vertically using the space at the rear of the trolleys.

[0004] In special circumstances, due to space constraints in the launching shaft, the total length of the launching shaft may be less than the total length of the tunnel boring machine (TBM), preventing the TBM from launching as a whole underground. The existing launching process involves: installing the launching base; assembling and debugging the TBM; installing the reaction frame; removing the tunnel portal; installing the portal seal; assembling the negative ring segments; and starting excavation. However, in the confined space of the launching shaft, the TBM and its supporting trolley cannot enter the tunnel as a whole, which can easily lead to problems such as poor end reinforcement and soil instability at the launching portal, resulting in risks such as portal collapse and end settlement.

[0005] Currently, there is a situation where the existing track space is not fully utilized during the tunnel boring machine (TBM) launching process, necessitating the rational use of the space on the other side track. Adopting a split-type launching method and ensuring reliable end reinforcement under space constraints allows for safe and reliable launching operations even in confined spaces.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method for the separate launching of a shield tunnel in a confined space, so as to solve the above-mentioned technical problems existing in the prior art.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] The present invention provides a method for the split-type initiation construction of a tunnel boring machine in a confined space, characterized by comprising the following steps:

[0010] S1: Before the separate launch of the shield tunneling machine, preparation work for the launch is carried out, including reinforcement of the launch end, installation of the shield launch bracket, assembly of the shield machine, installation of the reaction frame, and debugging of the shield machine system.

[0011] S2: Demolish the retaining piles of the starting tunnel portal and install the tunnel portal seal, and drill holes between the piles within the tunnel portal area to take samples of the reinforced strata to check the reinforcement effect and prevent the bottom layer from collapsing again;

[0012] S3: Assemble the negative ring segments and conduct a trial run of the tunnel boring machine as a whole. Spray a concrete protective layer on the tunnel face to prevent soil and groundwater loss. This is the third time to prevent ground subsidence.

[0013] S4: Remove the outer layer of steel bars, the tunnel boring machine enters the working face, and after the tail of the shield passes through the starting tunnel, backfill grouting is carried out behind the rear segments to begin the trial excavation stage;

[0014] S5: Trial tunneling to explore the optimal shield tunneling parameters suitable for tunneling in this geological section;

[0015] S6: After the trial excavation of 100m is completed, the negative pipe ring is removed and preparation for formal excavation is made. After 80 rings of excavation, the split launching trolley is connected to the tunnel boring machine to start normal excavation and complete the split launching.

[0016] Compared with the prior art, the shield tunneling split-type launching construction method provided by this invention, when the length of the launching shaft is less than the length of the shield machine, implements a triple guarantee measure of launching end reinforcement, pile drilling sampling within the opening range to check the reinforcement effect, and shotcrete protective layer at the tunnel face to prevent soil collapse during the launching stage. Attached Figure Description

[0017] Figure 1 A construction flowchart of a method for launching a shield tunnel in a confined space, provided in an embodiment of the present invention;

[0018] Figure 2 This is a cross-sectional view of the shield support frame according to an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them, and do not constitute a limitation on the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0020] First, the following explanations are provided for the terms that may be used in this article:

[0021] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0022] The terms “including,” “comprising,” “containing,” “having,” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, “including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.)” should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0023] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0024] Unless otherwise explicitly specified or limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this document according to the specific circumstances.

[0025] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” and “counterclockwise” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience and simplification of description and do not imply that the device or component 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 document.

[0026] The contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0027] The present invention provides a method for the separate launching and construction of a tunnel boring machine in a confined space, comprising the following steps:

[0028] S1: Before the separate launch of the shield tunneling machine, preparation work for the launch is carried out, including reinforcement of the launch end, installation of the shield launch bracket, assembly of the shield machine, installation of the reaction frame, and debugging of the shield machine system.

[0029] S2: Demolish the retaining piles of the starting tunnel portal and install the tunnel portal seal, and drill holes between the piles within the tunnel portal area to take samples of the reinforced strata to check the reinforcement effect and prevent the bottom layer from collapsing again;

[0030] S3: Assemble the negative ring segments and conduct a trial run of the tunnel boring machine as a whole. Spray a concrete protective layer on the tunnel face to prevent soil and groundwater loss. This is the third time to prevent ground subsidence.

[0031] S4: Remove the outer layer of steel bars, the tunnel boring machine enters the working face, and after the tail of the shield passes through the starting tunnel, backfill grouting is carried out behind the rear segments to begin the trial excavation stage;

[0032] S5: Trial tunneling to explore the optimal shield tunneling parameters suitable for tunneling in this geological section;

[0033] S6: After the trial excavation of 100m is completed, the negative pipe ring is removed and preparation for formal excavation is made. After 80 rings of excavation, the split launching trolley is connected to the tunnel boring machine to start normal excavation and complete the split launching.

[0034] In step S1:

[0035] The reinforcement of the starting end involves soil reinforcement within a certain range above the tunnel entrance, outside the tunnel's axis of symmetry, including grouting reinforcement within an 8m range of the starting end.

[0036] The shield tunneling machine launching bracket is installed after the bottom plate of the station's starting end is completed. The center line of the launching bracket is determined according to the design center line of the tunnel at this location. The center of the bracket coincides with the center line of the track. The shield tunneling machine bracket is raised by 20mm and leveled using steel plates. The shield tunneling machine bracket is then welded to the pre-embedded steel plates of the station's bottom plate.

[0037] Due to site limitations, the tunnel boring machine (TBM) was assembled in stages within the station. Following the assembly sequence, the components were hoisted down into the shaft, and then connected and assembled. The steps included:

[0038] S1.1: Lay the track to connect the starting shaft and the standard section, and put the battery car that pulls the shield tunneling trolley into the shaft;

[0039] S1.2: After the trolley wheels are installed on the ground, hoist the trolley into place according to the split launch arrangement requirements and place it on the trolley track;

[0040] S1.3: Hoist the segment trolley into place and install it on the track;

[0041] S1.4: The connecting bridge is hoisted in and slowly sent to the front of the trolley using the segment trolley. One end of the connecting bridge is connected to the trolley, and the other end is supported by steel sections to maintain its balance.

[0042] S1.5: The main unit shall be lowered into the well in the following order: screw conveyor, front shield, middle shield, cutterhead, assembly machine, and shield tail.

[0043] The bottom of the column for installing the reaction frame is welded to the reserved steel plate in the station, the upper part is supported by steel sections on the middle plate of the station behind, and the bottom is supported by steel pipes on the structural wall. After the reaction frame is fixed, the rear diagonal brace is welded.

[0044] The tunnel boring machine commissioning includes no-load commissioning and load commissioning.

[0045] In step S2:

[0046] The initial portal retaining piles were accurately positioned at the center line of the tunnel portal. The interior of the portal was excavated and laid out. The portal was removed using a manual pneumatic pick.

[0047] The sealing doorway is installed with an annular sealing rubber plate around the tunnel boring machine entrance circle on the inner lining wall. A pre-embedded steel ring with screw holes is installed around the entrance hole circle of the inner lining wall. The pre-embedded steel ring is welded with anchor bars and connected to the main body. The sealing rubber plate and the fan-shaped pressure plate are bolted to the pre-embedded steel ring.

[0048] In step S3:

[0049] The negative tube ring consists of 10 rings, numbered -10 to -1. The -10 ring is pushed to the front face of the reaction frame by empty assembly and movement in front of the shield tail brush. Before empty assembly, guide rails and limiting plates are welded. After the -10 ring is assembled, jacks are used to push the entire -10 ring to the reaction frame. After the tunnel boring machine advances about 1800mm, the assembly of the -9 ring begins.

[0050] In step S4:

[0051] The backfill grouting behind the tunnel segments adopts synchronous grouting at the shield tail and secondary supplementary grouting.

[0052] In step S5:

[0053] The determined tunneling parameters are the optimal shield tunneling parameters suitable for tunneling in this geological section.

[0054] In step S6:

[0055] The separate starting arrangement includes: No. 1 trolley is located inside the station structure, the connecting bridge is located inside the station structure, No. 4 trolley is located on the station floor, No. 3 trolley is located on the station floor, No. 2 trolley is located on the station floor, No. 6 trolley is located on the middle slab of the second basement level station, and No. 5 trolley is located on the middle slab of the second basement level station.

[0056] Before the 80th ring, a single trolley is connected to the main shield machine, while the remaining trolleys are set up in the starting station structure on one side of the adjacent line and excavated using small soil buckets.

[0057] The initial end reinforcement in step S1, the sampling and inspection of the reinforcement effect by drilling between piles within the opening range in step S2, and the shotcrete protective layer at the working face in step S3 are triple soil anti-collapse protection measures.

[0058] In summary, the shield tunneling method for split-stage launching in confined spaces, as described in this invention, takes into account the actual engineering conditions and includes pre-construction reinforcement of the launching end, tooling assembly, and shield machine assembly. During launching, the tunnel portal is broken up and sealed, negative ring segments are assembled, and the entire machine is debugged. Using a split-stage launching method, the outer layer of reinforcing steel is removed first, the tail of the shield is backfilled and grouted, and then the trolley and shield body are connected. When the length of the launching shaft is less than the overall length of the shield machine, the construction method is improved and the construction sequence is adjusted. Three safeguards are implemented: reinforcement of the launching end, sampling of piles within the tunnel portal area to check the reinforcement effect, and a shotcrete protective layer at the tunnel face, to prevent soil collapse during the launching stage.

[0059] The beneficial technical effects of this invention are as follows:

[0060] 1. Before the initial construction of the separate sections, three reinforcements were carried out to prevent soil collapse, which improved the problem of soil collapse in the initial section.

[0061] 2. Utilize the space on the other side of the track for hoisting and lowering operations, making more rational use of the limited and confined space.

[0062] 3. By improving construction methods and adjusting construction sequence, the launching operation, where the length of the launching wellhead is less than the length of the entire shield machine, can be carried out through segmented construction, which fundamentally solves the problems of limited space and high construction difficulty.

[0063] To more clearly demonstrate the technical solution and its effects provided by the present invention, the embodiments of the present invention will be described in detail below with reference to specific examples.

[0064] Example 1

[0065] like Figure 1 , Figure 2 As shown:

[0066] This invention provides a method for the segmented launching of a shield tunnel in a confined space. The method employs grouting in multiple segments to prevent soil collapse and falls, and uses a reasonable segmented launching procedure to solve the problem that launching operations cannot be carried out when the length of the launching shaft is less than the length of the entire machine.

[0067] The specific technical solution is as follows:

[0068] I. Preparations before starting the split

[0069] Deep-hole grouting was used to reinforce the shield tunnel end reinforcement area, using a cement grout and water glass dual-liquid grout. The injection pressure was controlled within the range of 0.2MPa to 0.3MPa. The reinforcement length at the shield starting end was 8m, and grouting reinforcement was carried out within 3m outside the tunnel segments. The left and right lines of the section were reinforced separately. The grouting holes at each tunnel entrance were divided into horizontal holes, outermost inclined holes, and central inclined holes. The outermost inclined holes had four angles: 10°, 20°, 35°, and 55°. The peak value of the deep-hole grouting pressure was controlled at 0.8 to 1.0MPa.

[0070] II. Installation of the launching base

[0071] The launching bracket is divided into two parts, which are hoisted by a 50t crawler crane. The center line of the bracket is aligned with the center line of the track. The center line of the bracket is marked on the bottom, end wall and side wall of the launching manhole to indicate the installation position of the bracket. The launching bracket is raised by 20mm for installation. The bracket is leveled by steel plate padding. The bracket and the pre-embedded steel plate of the station floor are welded and positioned.

[0072] III. Tunnel Boring Machine Lifting and Assembly

[0073] The track is laid using a support frame and sleeper rails inside the launching shaft, creating a slope between the launching shaft and the standard section track. The standard section sleepers use H10 steel, and the track uses 24kg / m steel rails. After the track is laid, a 25t battery-powered car is placed into the shaft and a winch is installed. After the trolley wheels are installed on the ground, the trolleys are hoisted in according to the split launching arrangement and placed on the trolley tracks without being connected. The split launching arrangement is as follows: Trolley No. 1 is located inside the station structure, the connecting bridge is located inside the station structure, Trolley No. 4 is located on the station floor, Trolley No. 3 is located on the station floor, Trolley No. 2 is located on the station floor, Trolley No. 6 is located on the middle slab of the second basement level station, and Trolley No. 5 is located on the middle slab of the second basement level station. Two segment cars are hoisted in and placed on 900mm gauge tracks. The connecting bridge is sent to the front of the trolley using the segment cars, and one section of the connecting bridge is connected to Trolley No. 1. One end is temporarily supported by structural steel; the next segment car lifts the screw conveyor into the shaft, places it upright on the segment car, fixes it, and tows it to the rear end of the launching shaft; remove the support sleepers and tracks within the lifting shaft opening area; lift the middle shield after turning it over on the ground and then lift it into the shaft; turn the front shield over on the ground, lift it, and install the central rotating body; lift the front shield into the shaft; clean the contact surfaces of the front and middle shields and tighten the bolts; push the front and middle shields and the connection position to the pre-reserved groove for welding on the bottom plate of the launching shaft, weld and seal the front and middle shields; lower the cutterhead and connect it to the front shield and the central rotating body; assemble the segment assembly machine and guide rails on the ground and lower it into the shaft; lift the shield tail into the shaft and move it horizontally, clean the hinge surface and the contact surface between the middle shield and the shield tail, apply lubricating grease and install the hinge seal; push out the connecting bridge and connect it to the rear matching trolley and the shield tail, cut off all lifting lugs and grind them.

[0074] IV. Installation of reaction frame

[0075] The position of the reaction frame is measured starting from the centerline of the mileage section; the centerline of the well is marked on the side wall of the starting well and the positioning plane of the reaction frame is close to the negative ring segment, perpendicular to the tunnel axis at this point, and the center positioning of the reaction frame is performed; the bottom of the reaction frame column is welded to the reserved steel plate of the station, the bottom is supported by steel pipe on the structural wall, and the upper part is supported by steel section on the reserved steel plate of the station; after the reaction frame is fixed, the rear diagonal brace is welded.

[0076] V. Tunnel Boring Machine Commissioning

[0077] The system equipment inspection includes the hydraulic system, lubrication system, cooling system, power distribution system, and grouting system; testing and calibration of various instruments; commissioning of the electrical components, including checking power supply, checking motors, setting and testing subsystem parameters, testing the entire machine, and further commissioning; commissioning of the hydraulic components, including the propulsion and articulation system, screw conveyor, segment installation machine, segment crane and trolley, foam and bentonite system, grouting system, and belt conveyor; and load testing of the entire tunnel boring machine.

[0078] VI. Demolition of the tunnel portal and installation of portal seals

[0079] Accurately locate the center line of the tunnel portal and excavate and lay out the interior of the portal; erect double-row scaffolding and excavate in sections according to the order of top to bottom and sides to the middle; after excavating the reinforcing steel of the back soil wall, cut it off with oxyacetylene welding and penetrate the remaining retaining structure; after the excavation is completed, dismantle the scaffolding and quickly assemble the negative ring segments to allow the tunnel boring machine to reach the working face; install L-shaped embedded steel rings with M27 bolts around the entrance ring of the inner lining wall; use bolts to connect the sealing rubber plate and the fan-shaped pressure plate to the embedded steel ring to form a portal seal; set bolt holes on the sealing steel ring and fix the curtain rubber plate between the two rings; the curtain rubber plate is installed by wrapping around the inner ring of the sealing ring.

[0080] VII. Assembly of Negative Ring Segments

[0081] Install the -10 ring segment inside the shield tail, push it out to the shield tail and directly connect it to the reference ring with bolts and tighten it, ensuring that the segment is at the same inclination angle as the tunneling route; when the shield machine advances to -9 to -6 rings, welded blocks to restrict the shield machine's movement and then assemble the segments; before advancing to -5 ring, install anti-torsion blocks on the shield body, at which point the cutterhead begins to cut the soil and install the -5 ring segment; when advancing to -4 ring, start using the auger to remove soil and install the -4 ring segment up to -1 ring.

[0082] VIII. Shield Tail Grouting and Trial Excavation

[0083] When the tunneling reaches the first ring, the shield tail sealing brush of the tunnel boring machine enters the portal ring plate device, and the shield tail grouting begins while tunneling continues; grout is injected directly into the shield tail gap through the injection port installed on the tunnel boring machine; secondary grouting is carried out after the segments separate from the shield tail 6 rings.

[0084] IX. Separate Launch and Final Operations

[0085] The No. 1 trolley is connected to the shield machine, and the other trolleys are set up in the structure of the starting station on the adjacent route. Small soil buckets are used to excavate soil up to the 80th ring. After the 80th ring, the trolleys are connected to the shield machine, thus completing the split launch of the shield.

[0086] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for split-type shield tunneling in confined spaces, characterized in that, Includes the following steps: S1: Before the separate launch of the shield tunneling machine, preparation work for the launch is carried out, including reinforcement of the launch end, installation of the shield launch bracket, assembly of the shield machine, installation of the reaction frame, and debugging of the shield machine system. S2: Demolish the retaining piles of the starting tunnel portal and install the tunnel portal seal, and drill holes between the piles within the tunnel portal area to take samples of the reinforced strata to check the reinforcement effect and prevent the bottom layer from collapsing again; S3: Assemble the negative ring segments and conduct a trial run of the tunnel boring machine as a whole. Spray a concrete protective layer on the tunnel face to prevent soil and groundwater loss. This is the third time to prevent ground subsidence. S4: Remove the outer layer of steel bars, the tunnel boring machine enters the working face, and after the tail of the shield passes through the starting tunnel, backfill grouting is carried out behind the rear segments to begin the trial excavation stage; S5: Trial tunneling to explore the optimal shield tunneling parameters suitable for tunneling in this geological section; S6: After the trial excavation of 100m is completed, the negative pipe ring is removed and preparation for formal excavation is made. After 80 rings of excavation, the split launching trolley is connected to the shield machine to start normal excavation and complete the split launching. In step S1: The reinforcement of the starting end involves soil reinforcement within a certain range above the tunnel entrance, outside the tunnel's axis of symmetry, including grouting reinforcement within an 8m range of the starting end. The shield launching bracket is installed after the bottom plate of the station's starting end is completed. The center line of the launching bracket is determined according to the design axis of the tunnel at this location. The center of the shield launching bracket coincides with the center line of the line. The shield launching bracket is raised by 20mm and leveled with steel plates. The shield launching bracket is then welded to the pre-embedded steel plates of the station's bottom plate. In step S1: Due to site limitations, the tunnel boring machine (TBM) was assembled in stages within the station. Following the assembly sequence, the components were hoisted down into the shaft, and then connected and assembled. The steps included: S1.1: Lay the track to connect the starting shaft and the standard section, and put the battery car that pulls the shield tunneling trolley into the shaft; S1.2: After the trolley wheels are installed on the ground, hoist the trolley into place according to the split launch arrangement requirements and place it on the trolley track; S1.3: Hoist the segment trolley into place and install it on the track; S1.4: The connecting bridge is hoisted in and slowly sent to the front of the trolley using the segment trolley. One end of the connecting bridge is connected to the trolley, and the other end is supported by steel sections to maintain its balance. S1.5: The main unit shall be lowered into the well in the following order: screw conveyor, front shield, middle shield, cutterhead, assembly machine, and shield tail. The bottom of the column for installing the reaction frame is welded to the reserved steel plate in the station, the upper part is supported by steel sections on the middle plate of the station behind, and the bottom is supported by steel pipes on the structural wall. After the reaction frame is fixed, the rear diagonal brace is welded. The tunnel boring machine commissioning includes no-load commissioning and load commissioning; In step S6: The separate starting arrangement includes: No. 1 trolley is located inside the station structure, the connecting bridge is located inside the station structure, No. 4 trolley is located on the station floor, No. 3 trolley is located on the station floor, No. 2 trolley is located on the station floor, No. 6 trolley is located on the middle slab of the second basement level station, and No. 5 trolley is located on the middle slab of the second basement level station. Before the 80th ring, a single trolley is connected to the main shield machine, while the remaining trolleys are set up in the starting station structure on one side of the adjacent line and excavated using small soil buckets.

2. The method for split-type shield tunneling in confined spaces according to claim 1, characterized in that, In step S2: The initial portal retaining piles were accurately positioned at the center line of the tunnel portal. The interior of the portal was excavated and laid out. The portal was removed using a manual pneumatic pick. The installation portal seal is installed around the shield machine entrance circle on the inner lining wall with an annular sealing rubber plate. A pre-embedded steel ring with bolt holes is installed around the shield machine entrance circle. The pre-embedded steel ring is welded with anchor bars and connected to the main body. The sealing rubber plate and the fan-shaped pressure plate are bolted to the pre-embedded steel ring.

3. The method for split-type shield tunneling in confined spaces according to claim 2, characterized in that, In step S3: The negative tube ring consists of 10 rings, numbered -10 to -1. The -10 ring is pushed to the front face of the reaction frame by empty assembly and movement in front of the tail brush. Before empty assembly, guide rails and limiting plates are welded. After the -10 ring is assembled, jacks are used to push the entire -10 ring to the reaction frame. After the tunnel boring machine advances 1800mm, the assembly of the -9 ring begins.

4. The method for split-type shield tunneling in confined spaces according to claim 3, characterized in that, In step S4: The backfill grouting behind the tunnel segments adopts synchronous grouting at the shield tail and secondary supplementary grouting.

5. The method for split-type shield tunneling in a confined space according to any one of claims 1 to 4, characterized in that, The initial end reinforcement in step S1, the sampling and inspection of the reinforcement effect by drilling between piles within the opening range in step S2, and the shotcrete protective layer at the working face in step S3 are triple soil anti-collapse protection measures.

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