Prefabricating method and prefabricating mold of shield segment and duct core mold

Abstract

The invention relates to a shield segment prefabrication method, a prefabrication mold and a duct core mold. The hole channel core mold comprises a core mold support, the core mold support comprises a core mold supporting support and a core mold expansion support, the core mold supporting support is a linear cylinder, and the diameter of the axial section of the core mold expansion support is gradually increased. The end, with the smaller diameter, of the core mold expansion support is connected with the core mold supporting support, the core mold supporting support is detachably inserted into the end of the core mold and fixed in the mode that the core mold supporting support is matched with the diameter of the core mold, and an expansion section with the gradually-changed diameter is formed at the end of the hole channel. According to the shape structure of the core mold supporting bracket, the material length of the core mold is shortened under the condition that the shape of the end part of the core mold is maintained, the resistance of concrete flowing towards the end parts on the two sides in the pouring process is reduced, meanwhile, the strength of the end parts of the core mold is enhanced, and the deformation of the end parts of the core mold is avoided. According to the invention, the core mold expansion bracket is easy to separate from the expansion section, and the resistance between the prestressed steel beam and the hole wall at the end part of the shield segment is relatively small.

Description

A prefabrication method of a shield segment, a prefabrication mold and a duct core mold TECHNICAL FIELD

[0001] The present application relates to the technical field of shield tunneling, in particular to a prefabrication method of a shield segment and a duct core mold thereof. BACKGROUND

[0002] The channel reserved inside the shield segment is mainly designed to serve the diversified functional requirements of the tunnel system, covering application scenarios such as ventilation system layout, drainage pipeline installation, cable laying and auxiliary pipeline embedding. Among them, the ring-arranged ducts embed prestressed steel strands, which can significantly improve the mechanical properties and stability of the segment structure, thereby strengthening the overall compression resistance and crack resistance of the tunnel.

[0003] The core function of the prestressed steel strand in the segment can be summarized as follows: first, by applying the prestress, the segment forms a compression stress field when subjected to external loads, which can effectively offset the tensile stress caused by external loads, reduce the risk of structural cracking, and simultaneously improve the stiffness and bearing stiffness. Second, the crack control function is significant. When the tunnel encounters uneven settlement or lateral soil pressure, the prestressed steel strand can effectively inhibit the crack propagation trend, control the crack width and length, and ensure the structural integrity. Through scientific arrangement of the steel strand position, the structural stability under complex load conditions can be realized. Third, the bearing capacity is enhanced. After the steel strand is tensioned, the resistance of the segment to external forces such as soil pressure and groundwater pressure can be improved. Fourth, the structural performance is optimized, which not only improves the seismic performance and anti-deformation ability, but also improves the overall dynamic response characteristics. Fifth, the service life is extended. The prestress effect of the steel strand can slow down the damage accumulation of the segment during service, and combined with the corrosion-resistant coating treatment, the long-term operation safety is further ensured.

[0004] Currently, the difficulties encountered in the prefabrication process of the shield segment mainly focus on the duct core mold design and the concrete pouring process, which can be summarized as follows:

[0005] First, the fixing difficulty of the expanding trumpet design is increased.

[0006] If the ends of the corrugated pipe core mold are designed as a cone or a trumpet to optimize the duct structure, the trumpet part in the mold is prone to displacement or deformation due to the pressure and vibration of the concrete pouring, resulting in insufficient stability of the core mold.

[0007] Additional support structures (such as steel binding, positioning supports) need to be designed to ensure the position of the core mold, but such structures will increase the complexity of the mold and the construction cost.

[0008] Materials that can withstand pouring pressure and vibration (such as high-strength adhesives or detachable buckles) need to be selected, but existing materials may not be able to balance durability and detachability.

[0009] Second, the limitation of keeping the end diameter of a conventional channel constant.

[0010] The constant diameter of the existing ducts makes it difficult to precisely align the prestressed steel strands at misaligned joints, easily leading to stress concentration and reducing the overall structural integrity and sealing performance. Uneven distribution of prestress within the ducts also affects the tunnel's load-bearing capacity and crack resistance.

[0011] Third, the flow of concrete is obstructed.

[0012] An expanded bell-shaped design may hinder the uniform flow of concrete around the duct, leading to uneven concrete distribution in certain areas and affecting the shape and quality of the duct. Variations in the bell-shaped design can easily create air bubbles or voids during pouring, reducing the duct's density and strength. Furthermore, the vibrator may struggle to effectively cover the bell-shaped area, potentially resulting in insufficient concrete density in that area and creating weak points at the interface between the duct and the tunnel segment.

[0013] Fourth, the installation of prestressed steel strands is difficult.

[0014] When connecting misaligned sections, the unchanged diameter at the end of the duct complicates the process of threading the steel strands, increasing construction time and labor costs. Loose connections between ducts at misaligned sections can lead to water seepage, threatening the long-term stability of the tunnel. If the core mold is embedded in concrete (e.g., a rigid pipe core mold), it cannot be reused, increasing material costs; if a removable core mold (e.g., a corrugated pipe) is used, a balance must be struck between flexibility and structural stability to prevent deformation during pouring.

[0015] Therefore, while improving the shape of the duct (such as a flared opening) can improve prestress transfer and staggered connections, it significantly increases the difficulty of fixing the core mold and the complexity of concrete pouring. While ensuring the duct's sealing and prestress uniformity, the operability of the pouring process and cost control must also be considered.

[0016] For example, CN115674423A discloses a new type of jacking pouring type concrete segment prefabrication process, comprising the following steps: S1: checking all molds before construction, checking whether there is deformation and damage, and removing surface residues to ensure that the inner surface of the mold is smooth, then brushing release agent on all inner surfaces; fixing the embedded parts on the top mold or the bottom mold according to the drawing requirements, and checking the stability of the embedded parts; S2: completing the binding of the steel reinforcement cage according to the drawing requirements, and binding and fixing a plurality of concrete pads on the inner and outer sides and the bottom of the steel reinforcement cage as temporary support for the steel reinforcement cage during pouring, and simultaneously forming a concrete protection layer for the segment; S3: closing the side mold and the end mold in turn, and clamping the locking clamps between the side mold and the end mold to make them fixed on the bottom mold; S4: hoisting the steel reinforcement cage into the mold, adjusting the gap between the steel reinforcement cage and the side mold and the end mold, and checking the stability of the steel reinforcement cage in the mold to ensure the thickness of the concrete protection layer on the side of the segment; S5: hoisting the top mold, accurately positioning the position of the top mold through positioning pins, making the four edges of the top mold fall on the side mold and the end mold, and clamping the locking clamps around the top mold and the side mold and the end mold; S6: adjusting the jacking device to tilt the mold to the set maximum angle and keep it, pouring concrete into the mold through the pouring opening, starting the variable frequency vibrator at the same time, adjusting the frequency of the vibrator at different positions as the height of the poured concrete rises, discharging the air between the segment concrete and the mold, and closing the observation hole in time as needed; S7: when the concrete is poured to the vicinity of the pouring opening, adjust the jacking device to slowly lower the mold to the intermediate inclination angle and keep it, continue to pour concrete and vibrate with the variable frequency vibrator; S8: when the concrete is poured again to the vicinity of the pouring opening, adjust the jacking device to slowly lower the mold to the horizontal position, continue to pour concrete to fill the mold cavity, and manually finish the surface according to the pouring opening of the top mold, complete the pouring of the segment; S9: steam curing the whole mold, demolding after the concrete strength reaches the demolding requirement, disassembling all locking clamps, hoisting off the top mold, and opening the side mold and the end mold; S10: using the demolding suction cup or lifting device to hoist the concrete segment to the segment turning-over tool, and then transferring it to the storage yard for curing. The prefabrication process cannot build a trumpet-shaped hole in the shield segment.

[0017] Therefore, how to improve the prefabrication method of the shield segment and the hole core mold thereof to overcome the above-mentioned defects is a technical problem to be solved by the present application. SUMMARY

[0018] At present, there are many difficulties in optimizing the hole core mold. For example, simply designing the two ends of the corrugated pipe as a cone or an expanding trumpet shape, it is found that the core mold is difficult to be stably fixed.

[0019] Specifically, in terms of fixation: (1) Difficulty in fixation increases, the design of the expanding trumpet mouth increases the difficulty of fixing the corrugated pipe in the mold, as the trumpet mouth part may shift or deform during the concrete pouring process. (2) Difficulty in determining the fixing point, additional design of the fixing point or support structure is needed to ensure the stable position of the corrugated pipe in the mold, which may increase the complexity and cost of the mold. (3) Difficulty in selecting fixing materials, the fixing materials and methods need to withstand the pressure and vibration during the concrete pouring process to prevent the corrugated pipe from shifting or being damaged.

[0020] In terms of pouring: (1) Concrete flow is blocked, the expanding trumpet mouth may hinder the uniform flow of concrete, leading to uneven distribution of concrete around the hole, affecting the quality and shape of the hole. (2) Shape change of the trumpet mouth part may cause bubbles or voids during the concrete pouring process, affecting the compactness and strength of the hole. (3) Difficulty in vibration, the vibrator may not effectively reach the trumpet mouth part during the concrete pouring process, resulting in insufficient concrete density in that area.

[0021] To overcome the shortcomings of the prior art, the present application provides a shield segment hole core mold from a first aspect, comprising a core mold support, the core mold support comprising a core mold support bracket and a core mold expanding bracket, the core mold support bracket being a straight cylindrical body, and the core mold expanding bracket having a gradually increasing diameter in axial cross-section; the smaller end of the core mold expanding bracket is connected with the core mold support bracket, and the core mold support bracket is detachably inserted into the end of the core mold in a manner matching the diameter of the core mold and is fixed, so that the end of the hole forms an expanding section with a gradually changing diameter.

[0022] According to a preferred embodiment, the hole core mold further comprises a platform mold, the platform mold being connected with the core mold support and arranged at the side edge of the prefabricated mold of the shield segment, the inclined edge of the longitudinal cross-section of the platform mold forms a demolding angle with the axis thereof, the platform mold is installed in a manner expanding towards the side edge of the prefabricated mold according to the demolding angle, and the diameter of the platform mold is greater than the diameter of the core mold expanding bracket, so that the platform mold forms a demolding platform connected with the expanding section when the shield segment is prefabricated.

[0023] According to a preferred embodiment, the platform mold is connected with the core mold support and arranged at the side edge of the prefabricated mold of the shield segment, and the plane of the demolding platform formed by the platform mold is perpendicular to the axis of the expanding section.

[0024] According to a preferred embodiment, the extension lines of the side edges of the core mold expanding bracket intersect to form an expanding angle β, the value of the expanding angle β ranges from 20 to 50 degrees, so as to reduce the resistance of concrete flowing to the side edge of the prefabricated mold; the demolding angle of the platform mold ranges from 10 to 75 degrees, so that the stress between the demolding platform and the platform mold is not concentrated.

[0025] The application provides a prefabricated mold for a shield segment, at least one positioning hole is arranged at a side edge position of the prefabricated mold, and is used for fixing a hole core mold; an anchoring mold is arranged at a bottom of the prefabricated mold, and the other end of the core mold is fixed to a vertical side wall of the anchoring mold by an anchor.

[0026] According to a preferred embodiment, one end of the at least two core molds is fixed to the opposite vertical side walls of the anchoring mold by the anchor in a staggered manner.

[0027] According to a preferred embodiment, the core mold fixing member is used to fixedly connect the core mold support bracket and the platform mold in a manner that a bolt penetrates through the positioning hole of the side edge of the prefabricated mold; the inclined side of the longitudinal section of the platform mold forms a demolding angle with the axis of the platform mold; the platform mold is installed in a manner that the inclined side of the longitudinal section of the platform mold expands towards the side edge of the prefabricated mold according to the demolding angle; and the diameter of the platform mold is greater than the diameter of the core mold expanding bracket; and in the case that the prefabrication of the shield segment is completed, the platform mold makes the prefabrication of the shield segment form a demolding platform connected with the expanding section.

[0028] According to a preferred embodiment, the bottom of the prefabricated mold is provided with a groove mold, the groove mold is arranged at both sides of the anchoring mold, and the groove mold is arranged in a protruding arc-shaped structure to prefabricate a groove; the arc-shaped profile of the groove mold comprises a straight line section and an arc line section, and the straight line section and the arc line section are naturally connected; a first chamfer is arranged at the bending position of the vertical side wall and the bottom of the anchoring mold; the first chamfer is an inner fillet; and a second chamfer is arranged at the connection position of the groove mold and the anchoring mold; the second chamfer is an outer fillet.

[0029] The application provides a prefabrication method for a shield segment, which comprises the following steps: connecting the smaller-diameter end of the core mold expanding bracket with the core mold support bracket to form a core mold support bracket, detachably inserting the core mold support bracket into the end of the core mold in a manner that the diameter of the core mold support bracket matches the diameter of the core mold, and fixing the core mold support bracket; using a core mold fixing member to fixedly connect the core mold support bracket and a platform mold in a manner that a bolt penetrates through the positioning hole of the side edge of the prefabricated mold; preparing required concrete and pouring the concrete; after the shield segment is shaped, the core mold is not disassembled and forms a part of the hole; the core mold and the core mold support bracket make the prefabrication of the shield segment form a hole with expanding sections at both ends; and the platform mold makes the prefabrication of the shield segment form a demolding platform connected with the expanding sections.

[0030] According to a preferred embodiment, the method further comprises: arranging at least one socket at the longitudinal end face of the prefabricated mold; and connecting the sockets between the adjacent shield segments along the tunnel axis by means of a socket plug, so that the longitudinal end faces of the two adjacent shield segments can be connected and fixed.

[0031] According to a preferred embodiment, the method further comprises: arranging at least three hole core mold molds at the prefabricated mold, which pass through the shield segment along the circumferential direction, so that the shield segment comprises at least three holes passing through the two ends of the shield segment along the circumferential direction, and at least one of the holes is a redundant hole for introducing new prestressed steel strands in later maintenance.

[0032] According to a preferred embodiment, the prefabrication method comprises: fixing one end of the core mold by means of the hole core mold mold through the positioning hole by means of a bolt, and fixing the other end of the core mold by means of an anchor on the vertical side wall of the anchoring mold; wherein the ends of the at least two core molds are fixed by means of the anchor on the opposite two vertical side walls of the anchoring mold in the anchoring mold at the bottom of the prefabricated mold in a staggered manner, forming the crossing holes in the anchoring tooth block; and when the hole core mold mold is disassembled, the ends of the two side holes in the anchoring tooth block respectively comprise an expansion section, and the holes in the anchoring tooth block are cross arranged. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 is a structural schematic view of a hole core mold provided by the present application;

[0034] Fig. 2 is an angle schematic view of a core mold support provided by the present application;

[0035] Fig. 3 is a structural schematic view of a platform mold provided by the present application;

[0036] Fig. 4 is an angle schematic view of a core mold expansion support provided by the present application;

[0037] Fig. 5 is an enlarged structural schematic view of a core mold support provided by the present application;

[0038] Fig. 6 is a structural schematic view of a hole-free fixed mold provided by the present application;

[0039] Fig. 7 is a structural schematic view of a shield segment in a spliced state provided by the present application;

[0040] Fig. 8 is a structural schematic view of a hole formed by a core mold support in a spliced state provided by the present application;

[0041] Fig. 9 is a structural schematic view of an anchoring end standard segment provided by the present application;

[0042] Fig. 10 is a structural schematic view of a prefabricated mold provided by the present application;

[0043] Fig. 11 is an enlarged schematic view of the chamfer of the prefabricated mold provided by the present application;

[0044] Fig. 12 is a side view of the arrangement of the inner channel of the standard segment at the anchoring end provided by the present application;

[0045] Fig. 13 is a plan view of the arrangement of the inner channel of the standard segment at the anchoring end provided by the present application;

[0046] Fig. 14 is a first flowchart of the prefabrication method of the shield segment provided by the present application;

[0047] Fig. 15 is a second flowchart of the prefabrication method of the shield segment provided by the present application;

[0048] Fig. 16 is a third flowchart of the prefabrication method of the shield segment provided by the present application;

[0049] Fig. 17 is a schematic view of the structure of the shield segment with the top segment expanded provided by the present application;

[0050] Fig. 18 is a schematic view of the partial method of the anchoring tooth block of the shield segment provided by the present application;

[0051] Fig. 19 is a sectional view of the circumferential end face of the shield segment provided by the present application;

[0052] Fig. 20 is a schematic view of the longitudinal end face of the shield segment provided by the present application;

[0053] Fig. 21 is a schematic view of the socket-type positioning strip of the circumferential end face of the shield segment provided by the present application;

[0054] Fig. 22 is a sectional view of the planar structure of the shield segment provided by the present application.

[0055] List of Reference Signs 110: shield segment; 111: anchor end standard segment; 112: non-anchor end standard segment; 113: abutment segment; 114: capping segment; 120: duct; 121: expansion section; 123: stripping platform; 130: anchor; 140: anchoring assembly; 141: groove; 142: anchoring tooth; 143: anchoring concrete; 144: edge corner; 300: prestressed steel tendon; 400: precast mold; 410: groove mold; 411: anchoring mold; 420: core mold; 421: straight section; 422: curved section; 423: first chamfer; 424: second chamfer; 430: positioning hole; 440: core mold support; 450: core mold support support; 460: core mold expansion support; 470: core mold fixing member; 480: platform mold; 481: bolt; 482: connecting hole; 490: ductless fixing mold; 510: socket; 520: circumferential center line; 530: socket positioning bar; 540: circumferential end face; 550: longitudinal end face; 560: longitudinal center line. DETAILED DESCRIPTION

[0056] The following detailed description is made in connection with the accompanying drawings.

[0057] The core mold 420 of the duct 120 is typically a specially designed mold assembly used to form the shape and size of the duct 120 during concrete casting. The design and material selection of the core mold 420 need to consider factors such as stability, durability, and ease of removal during concrete casting and curing. Common types of duct core molds include wooden core molds, plastic core molds, metal core molds, rubber core molds, and composite core molds. A corrugated pipe is a special type of core mold 420, which is typically made of flexible material with a corrugated surface structure. The corrugated pipe as a core mold 420 is suitable for shield segments 110 that require the formation of circumferential ducts 120, especially in cases where the duct 120 needs to have a certain flexibility and sealing properties. The installation and removal of the corrugated pipe are relatively simple and can adapt to the needs of ducts 120 of different sizes and shapes. For example, the flexibility of the corrugated pipe allows it to adapt to minor deformations during the concrete casting process, reducing damage to the concrete structure. The corrugated structure of the corrugated pipe can increase its contact area with the concrete, improving the sealing and stability of the duct 120.

[0058] Preferably, if the core mold 420 is placed inside the pipe body and serves as a support and support, after stripping, the core mold 420 can be extracted and reused. If the core mold 420 is used directly instead of the pipe body, at this time the core mold 420 is embedded in the concrete to form the duct 120, becomes a component of the precast member and cannot be reused, in this case, the core mold 420 is usually a hard pipe.

[0059] Currently, the duct 120 formed by the corrugated pipe as the core mold 420 is prefabricated in an arc shape. The diameter of the duct 120 is the same. When multiple shield segments 110 are spliced to form a pipe ring, multiple ducts 120 are spliced to form a circular duct 120. When prestress is applied by the prestressed steel strand 300 inside the duct 120, the following problems often occur:

[0060] (1) Uneven prestress transmission: The end diameter of the ordinary duct 120 does not change, which may cause uneven transmission of the prestressed steel strand 300 in the duct 120, affecting the effective application of prestress.

[0061] (2) When the adjacent shield segments 110 are misaligned, the end diameter of the ordinary duct 120 does not change, which may cause difficulty in achieving precise butt joint of the duct 120 at the misaligned connection, thereby affecting the integrity and sealing of the segment, and also causing difficulty in the construction operation of the prestressed steel strand 300 inside the tunnel. At the misaligned connection, stress concentration may occur due to the unchanged diameter of the duct 120, affecting the structural strength and stability of the segment. During the misaligned construction process, it is necessary to ensure the precise butt joint and sealing of the duct 120, otherwise water seepage or structural damage may occur.

[0062] Therefore, the structure of the duct 120 should be optimized. However, the optimization of the core mold 420 of the duct 120 has encountered many problems. If the two ends of the corrugated pipe are simply designed as a tapered or expanded trumpet shape, it will be found that the core mold 420 cannot be stably fixed.

[0063] Specifically, in terms of fixation: (1) The fixation difficulty is increased, and the design of the expanded trumpet mouth will increase the fixation difficulty of the corrugated pipe in the mold, because the trumpet mouth part may be displaced or deformed during the concrete pouring process. (2) The fixation point is not easy to determine, and additional fixation points or support structures need to be designed to ensure the stable position of the corrugated pipe in the mold, which may increase the complexity and cost of the mold. (3) The fixation material is not easy to determine, and the fixation material and method need to be able to withstand the pressure and vibration during the concrete pouring process to avoid displacement or damage of the corrugated pipe.

[0064] In terms of pouring: (1) The concrete flow is blocked, and the expanded trumpet mouth may hinder the uniform flow of concrete, causing uneven distribution of concrete around the duct 120, affecting the quality and shape of the duct 120. (2) Due to the shape change of the trumpet mouth part, air bubbles or voids may be generated during the concrete pouring process, affecting the compactness and strength of the duct 120. (3) The vibration difficulty is increased, and the vibrator may not be able to effectively reach the trumpet mouth part during the concrete pouring process, resulting in insufficient compactness of the concrete in this area.

[0065] In view of the deficiencies of the prior art, the present application provides a core mold mold for a shield segment and a prefabricated mold thereof.

[0066] Embodiment 1

[0067] As shown in FIG. 1, the present application provides a core mold mold for a shield segment, which comprises a core mold support 440 and a platform mold 480. The core mold support 440 is detachably connected with the end of the core mold 420, thereby supporting the core mold 420 into a specified shape and fixing the position of the core mold 420. The platform mold 480 is connected with the core mold support 440 and arranged at the side edge position of the prefabricated mold 400 of the shield segment 110. The side edge position refers to the annular end of the prefabricated mold 400. The annular direction refers to the dimension around the circumferential direction of the prefabricated mold 400. The core mold fixing member 470 fixes and connects the core mold support 440 and the platform mold 480 by penetrating the side edge of the prefabricated mold 400 through the bolt 481. In this case, the core mold 420 and the core mold support 440 jointly act on the shield segment 110, so that the core 120 with the expansion section 121 is prefabricated. At the same time, the platform mold 480 makes the shield segment 110 prefabricated into the demolding platform 123 connected with the expansion section 121. Through the detachable connection installation mode, the core mold mold can be repeatedly used. Through the precise design of the core mold support 440 and the platform mold 480, the core mold 420 is stably supported in the prefabricated mold 400, and the end thereof is not easily displaced in the pouring process. This design helps to reduce the diameter and shape deviation of the core 120, and ensures that the core 120 can be accurately butt-jointed when spliced into a pipe ring.

[0068] As shown in FIG. 2, the core mold support 440 comprises a core mold support bracket 450 and a core mold expansion bracket 460. The core mold support bracket 450 is a straight linear column, and is inserted into the end of the core mold 420 and fixed in a manner matched with the diameter size of the core mold 420. The core mold expansion bracket 460 is formed in an expansion shape in a manner that the diameter of the axial section gradually increases, and the smaller end thereof is connected with the core mold support bracket 450, so that the end of the core 120 forms the expansion section 121 with gradually increasing diameter. Preferably, the core mold expansion bracket 460 is formed in a cone in a manner that the diameter of the axial section gradually increases.

[0069] The design of the core mold support bracket 450 not only maintains the shape of the end of the core mold 420, but also shortens the material length, reduces the resistance of the concrete flowing to both sides of the end in the pouring process, enhances the strength of the end, and avoids deformation. The structural design of the core mold expansion bracket 460 enables the core mold 420 to uniformly disperse stress when bearing the concrete pressure, reduces local stress concentration, thereby avoiding the distortion or deformation of the core mold 420.

[0070] As shown in FIG. 3, the inclined side of the longitudinal section of the platform mold 480 forms a demolding angle with its axis, the platform mold 480 is installed in a way that it expands towards the side of the precast mold 400 according to the demolding angle, and the diameter of the platform mold 480 is larger than that of the core mold expansion support 460, and the plane of the demolding platform 123 precast by the platform mold 480 is perpendicular to the axial direction of the expansion section 121 when the shield segment 110 is precast.

[0071] The setting of the platform mold 480 adjacent to the core mold expansion support 460 ensures that the radial surface of the core mold expansion support 460 is not fixed by the concrete pouring, and at the same time, due to the close fixing of the platform mold 480 and the side of the precast mold 400, the concrete cannot flow between the platform mold 480 and the precast mold 400, so that the platform mold 480 cannot be fixed relative to the shield segment 110. Therefore, such setting ensures the smooth demolding of the platform mold 480 and the core mold support 440.

[0072] The setting of the demolding angle also reduces the friction and resistance in the demolding process, making the demolding easier and smoother, improving the demolding efficiency, and at the same time, not easy to cause damage to the shield segment. The setting of the demolding angle also helps to uniformly disperse the force on the mold during the concrete pouring process. The larger diameter design makes the concrete pressure more evenly distributed on the demolding platform 123, reducing local stress concentration, thereby avoiding deformation or damage of the mold.

[0073] As shown in FIGS. 2 and 4, the extension lines of the side edges of the core mold expansion support 460 intersect to form an expansion angle β, and the value of the expansion angle β is in the range of 20-50°, so as to reduce the resistance of the concrete flowing to the side of the precast mold 400. The reasonable selection of the expansion angle β makes the concrete flow more smoothly, reduces the resistance of the concrete around the hole 120, and helps the uniform distribution and filling of the concrete.

[0074] Preferably, the angle of the expansion angle β is further preferably 25-35°. Further preferably, the angle of the expansion angle β is 30°. Setting the expansion angle β to 30° helps the core expansion support 460 to be easily removed from the expansion section 121 of the tunnel. Given the length of the expansion section 121, if the expansion angle β is too large, i.e. the expansion angle β of the expansion section 121 is too large, the side wall of the expansion section 121 of the shield segment will lose its guiding function, and when the segment misalignment occurs, the prestressed steel strand 300 cannot be smoothly introduced into the tunnel 120. The thickness of the wall is related to the stress bearing capacity. The thinner the wall, the lower the stress bearing capacity, and the thicker the wall, the higher the stress bearing capacity. Moreover, the size of the expansion angle β is related to the thickness of the wall. The size of the expansion angle β will cause the hole diameter of the expansion section 121 of the shield segment to change accordingly, thereby changing the thickness of the wall between the side of the shield segment and the hole. If the expansion angle β is too large, the hole diameter of the expansion section 121 of the shield segment will increase accordingly, and the wall will become thin. Therefore, the size of the expansion angle β cannot be arbitrarily set. If the expansion angle β is too small, when the segment misalignment occurs, the friction between the prestressed steel strand 300 and the hole wall of the expansion section 121 will increase, and the resistance to the movement of the prestressed steel strand 300 in the expansion section 121 cannot be effectively reduced. Therefore, the expansion angle β is set to 30° in the present application, so that the thickness of the hole wall of the expansion section 121 is sufficient to bear the stress, the core expansion support 460 is easily removed from the expansion section 121, and the resistance between the prestressed steel strand 300 and the hole wall of the shield segment is also small.

[0075] As shown in FIGS. 3 and 5, the demolding angle α of the platform mold 480 ranges from 10° to 75°, so that the stress between the demolding platform 123 and the platform mold 480 is not concentrated. Further preferably, the demolding angle α ranges from 15° to 65°. Further preferably, the demolding angle α is 20°. Reasonable setting of the demolding angle α also helps to improve the demolding efficiency. During the demolding process, the appropriate demolding angle α enables the demolding platform 123 to be more smoothly separated from the mold, reduces the friction and resistance in the demolding process, improves the speed and efficiency of demolding, and is not easy to cause damage to the shield segment.

[0076] If the core expansion support 460 is directly connected to the end of the prefabricated mold 400 only by the bolt 481, not only is it easy for the concrete to flow into the gap, but also there is no platform mold 480 to disperse the force, and the pressure of the concrete may cause stress concentration at the contact point between the core expansion support 460 and the prefabricated mold 400, which may cause local deformation or damage to the core expansion support 460 or the prefabricated mold 400. The concrete may directly impact the end of the prefabricated mold 400, causing the surface of the concrete to be uneven or forming defects. During the pouring process, the direct contact of the concrete with the core expansion support 460 and the prefabricated mold 400 may generate more vibration and noise.

[0077] The functions of the platform mold 480 include two aspects:

[0078] First, the platform mold 480 fills the gap between the core mold expansion support 460 and the precast mold 400, avoiding concrete flowing into the gap and forming obstacles on the surface of the core mold expansion support 460 that hinder demolding, so the diameter of the platform mold 480 is larger than the maximum diameter of the core mold expansion support 460. The platform mold 480 can improve the sealing performance between the core mold expansion support 460 and the end of the precast mold 400, especially in the case of possible minor unevenness between the core mold expansion support 460 and the end of the precast mold 400, the platform mold 480 can fill these unevenness, preventing air or concrete leakage.

[0079] Second, it is beneficial to fix the core mold expansion support 460. The shape and size of the core mold expansion support 460 affect the path and speed of concrete flow. Due to the existence of the expansion angle β, the concrete near the core mold expansion support 460 flows along the inclined profile, and the direction of force changes with the change of the expansion profile. When the concrete flows from the surface of the core mold 420 to the surface of the core mold expansion support 460, the direction of force gradually changes from vertical to horizontal, and the stress distribution is uneven. At this time, if the platform mold 480 is arranged between the core mold expansion support 460 and the end of the precast mold 400, the platform mold 480 can help more evenly transfer the weight and pressure of the concrete to the core mold expansion support 460 and the precast mold 400, reducing local stress concentration. The platform mold 480 can also absorb the impact force during concrete pouring, preventing the concrete from directly impacting the connection part of the core mold expansion support 460 and the precast mold 400, thereby reducing the risk of damage. The platform mold 480 can also reduce direct contact between the core mold expansion support 460 and the precast mold 400, thereby reducing vibration and noise.

[0080] Third, it is beneficial to demolding. The platform mold 480 provides an additional contact surface, making it easier for the shield segment to separate from the precast mold 400. In particular, when the four sides of the platform mold 480 are inclined and form a demolding angle α in the cross section, the larger surface of the platform mold 480 makes it easier to demold from the end of the shield segment. Because there is only a small amount of concrete or even no concrete formed obstacles in the gap between the core mold expansion support 460 and the platform mold 480, the resistance of the core mold expansion support 460 to demolding is reduced, and the wear of the core mold expansion support 460 is also reduced, prolonging its service life.

[0081] As shown in FIG. 10, the prefabrication mold 400 is provided with a groove mold 410 and an anchoring mold 411. The groove mold 410 is arranged on both sides of the anchoring mold 411. The groove mold 410 is arranged in a protruding arc shape to prefabricate the groove 141. The anchoring mold 411 is recessed relative to the groove mold 410 and forms a deep groove, so that the deep groove forms the anchoring tooth block 142 of the shield segment 110 after prefabrication. The core mold 420 is fixed in the anchoring mold 411, so that the intersecting hole 120 is formed in the anchoring mold 411. The circumferential prestress of the segment forms a closed loop, which is beneficial to the prestress tension of the pipe ring and makes the stress of the pipe ring formed by the shield segments 110 more uniform.

[0082] As shown in FIG. 9, the anchoring assembly 140 on the anchoring end standard segment 111 includes a groove 141 and an anchoring tooth block 142. The anchoring tooth block 142 is also provided with a hole 120. The groove 141 is arranged on the side of the anchoring tooth block 142, and the extension direction of the groove 141 is perpendicular to the central axis of the shield segment. In the prefabricated anchoring assembly 140, the tension end of the prestressed steel strand 300 is fixed by the anchoring concrete 143, so that the groove 141, the anchoring tooth block 142 and the anchoring concrete 143 form a force structure together. In this way, it is ensured that the tension force of the prestressed steel strand 300 can be effectively transmitted to the prestressed shield segment 110, thereby improving the overall stability and tensile performance of the structure.

[0083] As shown in FIG. 11, the arc profile of the groove mold 410 includes a straight line segment 421 and an arc line segment 422. The straight line segment 421 and the arc line segment 422 are naturally transitioned. The connection between the groove mold 410 and the anchoring mold 411 is provided with a second chamfer 424. The bending part of the vertical side wall and the bottom of the anchoring mold 411 is provided with a first chamfer 423.

[0084] Preferably, the groove mold 410 and the anchoring mold 411 are formed by butt welding two steel plates or bending a single steel plate. Preferably, the first chamfer 423 is an internal fillet. The first chamfer 423 cannot be less than 10 mm. The second chamfer 424 is an external fillet. The second chamfer 424 is at least 6 mm. The first chamfer 423 and the second chamfer 424 are oppositely arranged.

[0085] As shown in FIG. 6, when the hole 120 is not needed in the shield segment, the non-hole fixing mold 490 is arranged at the positioning hole 430 of the prefabrication mold 400 to plug the positioning hole 430, so as to prevent the concrete from flowing out of the positioning hole 430 during pouring. The non-hole fixing mold 490 is different from the platform mold 480 in that it is a circular sheet body, and the cross section of the longitudinal arrangement is not provided with a demolding angle a.

[0086] Embodiment 2

[0087] This embodiment is a further improvement of embodiment 1, and the repeated contents will not be described again.

[0088] The present application provides a prefabricated mold 400 of a shield segment, as shown in FIG. 10, the bottom of the prefabricated mold 400 is provided with a groove mold 410 and an anchoring mold 411. The groove mold 410 is arranged on both sides of the anchoring mold 411. The groove mold 410 is arranged in a protruding arc-shaped structure to prefabricate the groove 141. The anchoring mold 411 is recessed relative to the groove mold 410 and forms a deep groove, so that the deep groove forms the anchoring tooth block 142 of the shield segment 110 after prefabrication, and the groove mold 410 forms the groove 141 of the shield segment 110 after prefabrication.

[0089] As shown in FIG. 10, at least one positioning hole 430 is arranged at the side edge position of the prefabricated mold 400. As shown in FIG. 2 and FIG. 10, the bolt 481 penetrates the positioning hole 430, and the core mold fixing part 470 is bolted with the connecting hole 482 on the core mold expansion support 460, so as to fix one end of the core mold 420 through the channel core mold. The other end of the core mold 420 is fixed by the anchor 130 on the vertical side wall of the anchoring mold 411. The channel core mold includes the core mold support 440 and the platform mold 480, the core mold support 440 is connected with the end of the core mold 420 in a detachable manner, so as to support the core mold 420 to a specified shape. The platform mold 480 is connected with the core mold support 440 and arranged at the side edge position of the prefabricated mold 400 of the shield segment 110.

[0090] The prefabricated mold 400 of the present application makes the two ends of the channel 120 of the prefabricated shield segment 110 have expansion sections 121, and the channels 120 in the anchoring tooth block 142 are arranged in a cross manner, so that one end of the prestressed steel strand 300 in the channel 120 can be tensioned in the anchoring tooth block 142.

[0091] As shown in FIG. 13, one end of at least two core molds 420 is fixed by the anchor 130 in the anchoring mold 411 in a staggered manner on the opposite two vertical side walls of the anchoring mold 411, forming the channels 120 crossing in the anchoring tooth block 142. In the anchoring end standard segment 111, there is also a non-crossing channel 120. The non-crossing channel 120 forms a prestressed channel in the circumferential direction of the shield tunnel. In the circumferential direction, the non-crossing channel 120 is parallel to the crossing channel 120, or approaches parallel.

[0092] As shown in FIGS. 12 and 13, the core mold 420 is not disassembled and forms a part of the duct 120 after the shield segment is shaped. The end portions of the duct 120 on both sides of the anchoring tooth block 142 respectively include the expansion section 121 after the duct core mold is disassembled. In this portion, the anchoring device 130 is arranged in the anchoring tooth block 142. After the pre-stressed steel beam 300 is inserted into the duct 120, the anchoring device 130 is used to tension the pre-stressed steel beam 300 to form sufficient pre-stress. Such a design ensures the accurate position and stability of the core mold 420 during the prefabrication process. This design helps to improve the prefabrication accuracy of the duct 120 of the shield segment 110, ensures that the duct core mold can accurately penetrate the positioning hole 430 and fix the core mold 420, and also enables the pre-stressed steel beam 300 to form a closed loop in the circumferential direction of the segment, so as to realize the pre-stress tensioning of the segment ring, thereby improving the quality and consistency of the shield segment.

[0093] As shown in FIG. 1, the core mold fixing member 470 fixedly connects the core mold support 440 and the platform mold 480 in a manner that the bolt 481 penetrates the positioning hole 430 of the side edge of the prefabrication mold 400, the core mold 420 and the core mold support 440 enable the shield segment 110 to be prefabricated to form the duct 120 with the expansion section 121, and the platform mold 480 enables the shield segment 110 to be prefabricated to form the demolding platform 123 connected with the expansion section 121. Such a design enables the core mold 420 and the core mold support 440 to be quickly and stably installed, thereby improving the production efficiency.

[0094] As shown in FIG. 1, the core mold support 440 includes a core mold support bracket 450 and a core mold expansion bracket 460. The core mold support bracket 450 is a straight linear cylinder and is inserted into the end portion of the core mold 420 and fixed in a manner that the diameter of the core mold support bracket 450 matches the diameter of the core mold 420. The core mold expansion bracket 460 is formed in an expansion shape in a manner that the diameter of the axial section gradually increases, and the smaller-diameter end of the core mold expansion bracket 460 is connected with the core mold support bracket 450, so that the end portion of the duct 120 forms the expansion section 121 with gradually increasing diameter.

[0095] The combined design of the core mold support bracket 450 and the core mold expansion bracket 460 ensures the accurate expansion shape of the duct 120 and improves the structural integrity and functionality of the duct 120.

[0096] Embodiment 3

[0097] The embodiment provides a shield segment made of the mold of the embodiments 1 and 2.

[0098] As shown in FIG. 7, the shield segment 110 is composed of an anchoring end standard segment 111, a non-anchoring end standard segment 112, an adjoining segment 113, and a capping segment 114. The anchoring end standard segment 111 is equipped with an anchoring assembly 140. The non-anchoring end standard segment 112 is located between two anchoring end standard segments 111. The anchoring end standard segment 111 is connected to the adjoining segment 113, and the adjoining segment 113 is connected to the capping segment 114. Each shield segment 110 is designed with a tunnel 120 inside. As shown in FIG. 8, the number of tunnels 120 in each shield segment 110 is at least one, and each tunnel 120 is provided with an expansion section 121 at both ends. Ideally, the number of tunnels 120 in the shield segment 110 is two to four. When multiple shield segments 110 are assembled into a ring, the tunnels 120 inside them are also connected in sequence to form a continuous circular channel, as shown in FIG. 8. For example, the diameter of the non-expanded part of the tunnel 120 is 50-90 mm, preferably 56-66 mm. Further preferably, the diameter of the non-expanded part of the tunnel 120 is 56 mm in inner diameter and 60 mm in outer diameter. As can be seen from FIG. 7, the prestressed steel tendon 300 passes through these circular tunnels 120 and is tensioned at the anchoring assembly 140, thereby applying prestress to each shield segment 110.

[0099] The anchoring end standard segment 111, the non-anchoring end standard segment 112, the adjoining segment 113, and the capping segment 114 each have their own structural characteristics. For example, the central angle of the anchoring end standard segment 111 and the non-anchoring end standard segment 112 is set to be between 67.3 degrees and 67.5 degrees, the central angle of the adjoining segment 113 is also within this range, and the central angle of the capping segment 114 is set to be between 22.3 degrees and 22.5 degrees. As shown in FIG. 7, the sum of the central angles of all these segments is not less than 180 degrees. This assembly method causes the center of gravity of the prestressed shield tunnel to deviate from its geometric center, forming an eccentricity, thereby reducing the bending moment internal force of the shield segment 110.

[0100] This design causes the center of gravity of the prestressed shield tunnel to deviate from the geometric center, reducing the influence of the bending moment internal force on the segment, thereby improving the tunnel's ability to resist bending deformation and prolonging the tunnel's service life. In addition, by adjusting the eccentricity, the bending moment internal force of the shield segment 110 can be effectively reduced, which can greatly reduce the reinforcement of the shield segment 110, thereby reducing the engineering cost. Typically, the weight of each ring is reduced from about 1 t to about 600 kg, and the weight of the shield segment using steel fiber reinforced concrete is further reduced to about 300 kg.

[0101] As shown in FIGS. 7 and 9, the anchoring end standard segment 111 is provided with an anchoring assembly 140, the end faces of the two annular ends of which are parallel to the central axis of the pipe ring. The non-anchoring end standard segment 112 and the capping segment 114 are not provided with the anchoring assembly 140, the end faces of the two annular ends of which are also parallel to the central axis of the pipe ring, but the end faces of the two annular ends of the capping segment 114 are oppositely inclined. The structure of the abutting segment 113 matches that of the capping segment 114, the end face of the first annular end of which is parallel to the central axis of the pipe ring, which enables the abutting segment 113 to be assembled with the anchoring end standard segment 111; and the end face of the second annular end is oppositely inclined to the central axis of the pipe ring, and the angle of inclination is consistent with that of the annular ends of the capping segment 114, which enables the abutting segment 113 to be assembled with the capping segment 114.

[0102] Embodiment 4

[0103] The embodiment provides a prefabrication method of the shield segment 110 of the embodiments 1 to 3.

[0104] In the embodiment, the annular end face 540 refers to the connecting face of the shield segment 110 in the circumferential direction (i.e. the contact face of the adjacent segments in the same ring). The longitudinal end face 550 refers to the connecting face of the shield segment 110 in the direction of the tunnel axis (i.e. the contact face between the adjacent shield pipe rings).

[0105] The pouring step of the shield segment 110 containing the annular channel 120 is a delicate and technically demanding process, which needs to ensure the accuracy of the position, size and shape of the channel 120, and at the same time ensure the quality and structural strength of the shield segment 110. The existing pouring step of the shield segment 110 containing the annular channel 120 includes:

[0106] S1: Install the channel core mold assembly for forming the annular channel 120 in the steel reinforcement framework, and ensure that the position and direction of the core mold 420 are correct and fixed firmly.

[0107] S2: Place the steel reinforcement framework and the core mold 420 together in the prefabrication mold 400.

[0108] S3: Prepare the required concrete and pour the concrete. Pour the mixed concrete into the mold uniformly, and use a vibrator to vibrate the concrete to remove air bubbles and ensure the density of the concrete. During the pouring process, attention should be paid to control the pouring speed and thickness of the concrete to avoid poor flow or segregation of the concrete.

[0109] S4: After the pouring of the concrete is completed, perform necessary treatment on the surface of the shield segment 110, such as troweling, polishing, etc., to ensure that the surface is flat and smooth; and select necessary static placement according to the setting condition of the concrete.

[0110] S5: After the concrete surface treatment and standing are completed, appropriate pre-demoulding curing is performed on the shield segment 110, such as steam curing, covering heat-retaining and moisture-retaining materials, to ensure that the strength and durability of the concrete grow well.

[0111] S6: After the concrete reaches sufficient strength, the mould is removed, and the shield segment 110 is inspected, including the position, size, shape, etc. of the channel 120, to ensure that the segment meets the design requirements and construction standards.

[0112] S7: After the shield segment 110 is demoulded and inspected, necessary curing needs to be performed, such as curing agent curing, water spraying curing, pool curing, etc., to ensure the strength and durability of the concrete.

[0113] Unlike the prior art described above, in the present embodiment, as shown in FIG. 14, the prefabrication method of the shield segment 110 includes:

[0114] S100: The smaller-diameter end of the core mould expansion support 460 is connected with the core mould support 450 to form a core mould support 440.

[0115] S200: The core mould support 450 is detachably inserted into the end of the core mould 420 in a manner matching the diameter of the core mould 420 and is fixed.

[0116] S300: The core mould support 440 and the platform mould 480 are fixedly connected using the core mould fixing member 470 in a manner that the bolt 481 penetrates the positioning hole 430 of the annular end face 540 of the prefabrication mould 400.

[0117] S400: The required concrete is prepared and concrete pouring is performed.

[0118] S500: After the shield segment 110 is shaped, the core mould 420 is not removed and forms part of the channel 120. The core mould 420 and the core mould support 440 enable the shield segment 110 to be prefabricated to form the channel 120 with expansion sections 121 at both ends, and the platform mould 480 enables the shield segment 110 to be prefabricated to form the demoulding platform 123 connected with the expansion sections 121.

[0119] Alternatively, step S600 or S700 is performed before step S400 is performed.

[0120] S600: The core mould fixing member 470 is bolted with the connecting hole 482 on the core mould expansion support 460 by penetrating the positioning hole 430 with the bolt 481, thereby fixing one end of the core mould 420 through the channel core mould. The other end of the core mould 420 is fixed to the vertical side wall of the anchoring mould 411 by the anchor 130.

[0121] Specifically, one end of the at least two core molds 420 is fixed by the anchor 130 in the opposite two vertical sidewalls of the anchoring mold 411 in the bottom of the prefabricated mold 400 in a staggered manner, forming the intersecting channels 120 in the anchoring teeth 142.

[0122] When the channel core mold is disassembled, the end of the channel 120 on both sides of the anchoring teeth 142 respectively includes an expansion section 121. The channels 120 in the anchoring teeth 142 are arranged in a cross manner.

[0123] S700: When the shield segment 110 does not need to be provided with a channel 120, a non-channel fixing mold 490 is arranged at the positioning hole 430 of the prefabricated mold 400 to plug the positioning hole 430, so as to prevent the concrete from flowing out of the positioning hole 430 during pouring.

[0124] As shown in FIGS. 19 and 20, the longitudinal end face 550 of the shield segment 110 after demolding is provided with at least one socket 510. As shown in FIG. 19, the profile of the socket 510 is a gradually expanding trumpet shape. Preferably, at least one socket 510 is arranged on each of the two longitudinal end faces 550 of the shield segment 110. Preferably, there is a spacing between the multiple sockets 510 on the same longitudinal end face 550. As shown in FIG. 20, three sockets 510 are arranged on one longitudinal end face 550 of the shield segment 110.

[0125] In FIG. 22, the cross-shaped dashed lines are the circumferential center line 520 and the longitudinal center line 560 of the planar structure of the shield segment 110, respectively. The circumferential center line 520 (the transverse dashed line in FIG. 22) represents the axis of symmetry of the shield segment 110 in the circumferential direction (i.e., the diameter direction of the tunnel ring). The circumferential center line 520 is used to position the assembly position of the shield segment 110 in the circumferential direction. The longitudinal center line 560 (the longitudinal dashed line in FIG. 22) represents the axis of symmetry of the shield segment 110 in the axial direction of the tunnel (i.e., the tunneling direction). The longitudinal center line 560 is used to position the assembly alignment of the segment in the longitudinal direction (such as the connection between adjacent rings). As shown in FIG. 22, three sockets 510 are arranged on each of the two longitudinal end faces 550 of the shield segment 110, and there are a total of six sockets 510.

[0126] That is, at least one socket 510 is arranged on the longitudinal end face 550 of the prefabricated mold 400 before the concrete pouring is performed. In this way, after pouring and molding, multiple sockets 510 are embedded on the longitudinal end face 550 of the shield segment 110. The sockets 510 between the adjacent shield segments 110 in the axial direction of the tunnel are connected by socket plugs in a socket connection, so that the longitudinal end faces 550 of the two adjacent shield segments 110 can be connected and fixed. The socket 510 and the socket plug form a socket connector.

[0127] The socket 510 preferably comprises a pre-buried sleeve and a gasket. The spigot is a connecting rod. The material of the pre-buried sleeve is usually stainless steel, high-strength alloy or high-strength nylon plastic. Preferably, the material of the pre-buried sleeve can also be nylon plastic. The inner wall of the pre-buried sleeve is designed as a stepped shaft hole and is provided with an inner clamping structure. The pre-buried sleeve is used to provide an embedding space for the connecting rod, and at the same time, through the cooperation of the internal thread with the external thread of the connecting rod, mechanical fixation is achieved.

[0128] A gasket (such as a rubber ring or an elastic gasket) is arranged on the outer side of the pre-buried sleeve (close to the concrete part of the shield segment 110). When the connecting rod is inserted into the pre-buried sleeve, the gasket is compressed and deformed, filling the gap between the sleeve and the connecting rod, playing a sealing and buffering role, preventing water leakage and absorbing minor displacement during construction.

[0129] The connecting rod is a stepped shaft, one end of which is an outer clamping (matching the inner clamping of the pre-buried sleeve), and the other end is a smooth section (convenient for insertion). The rod body material is usually high-strength steel, and the surface can be plated or coated to prevent corrosion. Preferably, the rod body can also be provided with a shell made of nylon plastic, which covers the steel material. Since nylon plastic has toughness, the difficulty of clamping the rod body and the pre-buried sleeve is reduced, and the cost is also reduced. After the connecting rod is inserted into the pre-buried sleeve, the two are locked through clamping, locking the longitudinal end surface 550 of the adjacent shield segment 110, forming an axial rigid connection.

[0130] In the process of subsequent splicing of shield segments 110, the connecting rod, i.e., the spigot, is first inserted into the socket 510 of the spliced shield segment 110 along the axial direction of the tunnel, and then the socket 510 of the shield segment 110 to be spliced is pushed towards the spigot. In this way, the two sockets 510 at the positions between the two shield segments 110 are connected by the same spigot, thereby sequentially fixing the shield segments 110 along the axial direction of the tunnel.

[0131] The shield segment 110 provided by the embodiment provides an optimized assembly structure. The socket connector is a quick connection device designed based on the socket structure principle. The socket connector realizes the functions of quick positioning, fixing and dismounting between components through insertion and mechanical bearing. The optimized scheme reduces the number of assembly holes, which can expand the circumferential size of the anchoring tooth block 142 and the opening width of the groove 141. As shown in FIGS. 17 and 18, the improved anchoring tooth block 142 has a significantly increased size in the circumferential direction compared with the reference structure in FIG. 7. This structural improvement not only improves the spatial adaptability of the anchoring tooth block 142, but also effectively improves the operation space of equipment installation during the prestress tensioning process by increasing the opening size of the groove 141, thereby significantly improving the construction efficiency and safety.

[0132] Preferably, compared with the shield segment 110 in FIG. 7, the socket positioning strip 530 is added to the circumferential end surface 540 of the shield segment 110, as shown in FIG. 21. The socket positioning strip 530 generally includes one or more recessed / protruding positioning features. The socket positioning strip 530 is used to ensure accurate alignment and stable connection of the shield segment 110 during assembly. The socket positioning strip 530 is generally installed on the circumferential end surface 540 of the shield segment 110. For example, a socket positioning strip 530 with a recessed structure is fixed with a protruding socket positioning strip 530 of an adjacent shield segment 110 in the circumferential direction, which plays a triple role of guiding, positioning and auxiliary installation. The design purpose of the socket positioning strip 530 is to provide a stable positioning reference to ensure the quick and accurate assembly of the circumferential shield segment 110. In the embodiment, steps S300 and S600-S700 can be executed in sequence or in any order according to actual needs.

[0133] The non-anchoring end standard segment 112, the adjacent segment 113 and the capping segment 114 shown in FIG. 7 only include arc-shaped holes 120. Therefore, when pouring the non-anchoring end standard segment 112, the adjacent segment 113 or the capping segment 114, step S300 needs to be performed between steps S200 and S400, as shown in FIG. 14.

[0134] As shown in FIG. 15, when there is no need to set the hole 120, only step S700 is performed between steps S200 and S400.

[0135] The inside of the anchoring end standard segment 111 shown in FIG. 12 comprises an arc-shaped hole 120 and two holes 120 arranged in cross in the anchoring tooth block 142. As shown in FIG. 16, when the anchoring end standard segment 111 needs to be cast, steps S300 and S600 are simultaneously performed between steps S200 and S400, and the execution order of steps S300 and S600 is not strictly limited.

[0136] The shield segment 110 is further optimized and improved.

[0137] As shown in FIG. 17, the anchoring end standard segment 111, the non-anchoring end standard segment 112, the abutting segment 113 and the capping segment 114 are spliced to form a pipe ring. Preferably, the longitudinal length of the shield segment 110 in FIG. 7 is 1.2 meters, and the central angle of the capping segment 114 is 22.5°. The longitudinal length of the shield segment 110 in FIG. 17 is set to 1.5 meters. Compared with the shield segment 110 in FIG. 7, the circumferential width of the capping segment 114 in FIG. 17 is increased, for example, the central angle of the capping segment 114 is increased to 67.5°. This improvement effectively avoids the stress concentration phenomenon that may occur at the edge of the capping segment 114 when the shield machine applies a thrust force, thereby reducing the risk of structural damage during pipe ring splicing.

[0138] Preferably, as shown in FIG. 18, the edge angle 144 of the anchoring mold 411 is adjusted to an arc-shaped angle, and the edge angle 144 of the anchoring tooth block 142 is correspondingly formed as an arc-shaped angle structure. The arc-shaped angle structure can reduce the demolding resistance during the production of the shield segment 110, effectively reducing the risk of structural damage caused by demolding operation.

[0139] Preferably, at least three hole core molds are arranged through the two ends of the shield segment 110 in the circumferential direction in the prefabrication mold 400, so that the shield segment 110 comprises at least three holes 120 through the two ends of the shield segment 110 in the circumferential direction. At least one hole 120 is a redundant hole 120 for introducing a new pre-stressed steel strand 300 during later maintenance.

[0140] For example, on a shield segment 110 with a longitudinal length of 1.5 meters, at least three cores 420 can be preset during prefabrication, and at least three holes 120 through the two ends of the shield segment 110 in the circumferential direction are formed after the shield segment 110 is formed. The inner side of the shield segment 110 is also provided with a redundant hole communicating with the redundant hole 120, for introducing a new pre-stressed steel strand 300 into the redundant hole 120 through the redundant hole during subsequent maintenance.

[0141] Compared with the traditional prefabrication method which only provides two holes 120, the embodiment has a significant advantage in the later maintenance of the shield segment 110.

[0142] Specifically, in the prior art, when only two ducts 120 are arranged in the shield segment 110, if the prestressed steel strand 300 needs to be replaced, the original prestressed steel strand 300 needs to be completely removed and a new steel strand needs to be reinstalled. This process has the following technical defects: first, the removal operation is easy to cause local damage to the body of the shield segment 110; second, accurate positioning of the position of the duct 120 is required for reinstallation, and the construction precision requirement is high; third, a single maintenance period usually takes a lot of time, which seriously affects the tunnel operation efficiency. The embodiment of the present application provides a design scheme of reserving at least three ducts 120 (two of which are used for initial prestressed steel strand 300 arrangement, and the remaining at least one is used as a redundant duct 120) in the prefabrication stage, which realizes obvious improvement of the maintenance process. In the later maintenance, only the new prestressed steel strand 300 needs to be guided into the idle duct 120 along the ring direction by a special guide device, and then a hydraulic tensioning device is used to apply prestress to the new prestressed steel strand 300, and the anchoring connection is completed through the ring fixing piece, completely avoiding the traditional removal operation. This maintenance method shortens the single maintenance time and significantly improves the construction efficiency. The structural design of the shield segment 110 of the embodiment realizes double technical advantages through the pre-provision of the redundant duct 120: first, the modular maintenance mode significantly reduces the maintenance cost; second, by reserving the structural redundancy, the shield segment 110 can still maintain the designed bearing capacity after being maintained for many times, and the service period can be extended to at least twice that of the traditional structure. This structural innovation based on the preventive maintenance design concept not only reduces the whole life cycle maintenance cost through the redundant space design, but also ensures the safety of the tunnel structure through the non-destructive operation mode, which significantly improves the economy and reliability of the whole life cycle of the shield tunnel.

Claims

1. A tunnel core form for a shield segment, characterized in that, The core mold support (440) comprises a core mold support bracket (450) and a core mold expansion bracket (460), The core mold support bracket (440) comprises a core mold support bracket (450) and a core mold expansion bracket (460), The core mold support bracket (450) is a straight linear cylinder, The core mold expansion bracket (460) is gradually enlarged in diameter in axial section; The smaller diameter end of the core mold expansion bracket (460) is connected with the core mold support bracket (450), and the core mold support bracket (450) is detachably inserted into the end of the core mold (420) and fixed in a manner matching the diameter size of the core mold (420), so that the end of the hole (120) forms a gradually enlarged expansion section (121).

2. The tunnel segment core form mold of claim 1, wherein, The hole core mold further comprises a platform mold (480), The platform mold (480) is connected with the core mold support (440) and arranged at the side of the precast mold (400) of the shield segment (110), The plane of the demolding platform (123) formed by the platform mold (480) is perpendicular to the axis of the expansion section (121).

3. A tunnel segment core form mould according to claim 1 or 2, characterised in that, The inclined side of the longitudinal section of the platform mold (480) forms a demolding angle with the axis thereof, The platform mold (480) is installed in a manner of expanding towards the side of the precast mold (400) according to the demolding angle, and the diameter of the platform mold (480) is greater than that of the core mold expansion bracket (460), When the shield segment (110) is precast, the platform mold (480) forms the demolding platform (123) connected with the expansion section (121) of the shield segment (110).

4. A tunnel segment core form mould according to any one of claims 1 to 3, wherein, The extension lines of the sides of the core mold expansion bracket (460) intersect to form an expansion angle β, The expansion angle β ranges from 20° to 50°, so as to reduce the resistance of the concrete flowing to the side of the precast mold (400); The demolding angle of the platform mold (480) ranges from 10° to 75°, so that the stress between the demolding platform (123) and the platform mold (480) is not concentrated.

5. A precast form for a shield segment, characterized by, At least one positioning hole (430) is arranged at the side of the precast mold (400) for fixing the hole core mold, The other end of the core mold (420) is fixed to the vertical side wall of the anchoring mold (411) by the anchor (130); The core mold support (440) comprises a core mold support bracket (450) and a core mold expansion bracket (460), The core mold support bracket (450) is a straight linear cylinder, The core mold expansion bracket (460) is gradually enlarged in diameter in axial section; The smaller diameter end of the core mold expansion bracket (460) is connected with the core mold support bracket (450), and the core mold support bracket (450) is detachably inserted into the end of the core mold (420) and fixed in a manner matching the diameter size of the core mold (420), so that the end of the hole (120) forms a gradually enlarged expansion section (121). The core mold support (440) comprises a core mold support bracket (450) and a core mold expansion bracket (460), The core mold support bracket (440) comprises a core mold support bracket (450) and a core mold expansion bracket (460), The core mold support bracket (450) is a straight linear cylinder, The core mold expansion bracket (460) is gradually enlarged in diameter in axial section; The smaller diameter end of the core mold expansion bracket (460) is connected with the core mold support bracket (450), and the core mold support bracket (450) is detachably inserted into the end of the core mold (420) and fixed in a manner matching the diameter size of the core mold (420), so that the end of the hole (120) forms a gradually enlarged expansion section (121).

6. The precast form for a shield segment according to claim 5, wherein, The ends of the at least two core molds (420) are fixed by the anchors (130) in an interleaved manner on the opposite vertical side walls of the anchoring mold (411) within the anchoring mold (411).

7. A precast form for a shield segment according to claim 5 or 6, wherein, The bottom of the prefabricated mold (400) is provided with a groove mold (410) arranged on both sides of the anchoring mold (411), and the groove mold (410) is arranged in a protruding arc-shaped structure to prefabricate the groove (141).

8. A precast form for a shield segment according to any one of claims 5 to 7, wherein, The arc-shaped profile of the groove mold (410) on both sides of the anchoring mold (411) comprises a straight line segment and an arc line segment, which are naturally transitioned; The bending part of the vertical side wall and the bottom of the anchoring mold (411) is provided with a first chamfer; the first chamfer is an internal fillet; the connecting part of the groove mold (410) and the anchoring mold (411) is provided with a second chamfer; the second chamfer is an external fillet.

9. A precast form for a shield segment according to any one of claims 5 to 8, wherein, The anchoring mold (411) is recessed relative to the groove mold (410) and forms a deep groove, so that the deep groove forms an anchoring tooth block (142) of the shield segment (110) after prefabrication.

10. A method of prefabricating a segment of a tunneling shield, characterized in that, The prefabrication method comprises: connecting the end with a smaller diameter of the core mold expansion support (460) with the core mold support support (450) to form a core mold support (440), detachably inserting the core mold support support (450) into the end of the core mold (420) in a manner matched with the diameter of the core mold (420) and fixing it, using the core mold fixing member (470) to fixedly connect the core mold support (440) and the platform mold (480) in a manner that the bolt (481) penetrates the positioning hole (430) on the side of the prefabricated mold (400), preparing the required concrete and pouring the concrete, when the shield segment (110) is shaped, the core mold (420) is not disassembled and forms part of the tunnel (120); the core mold (420) and the core mold support (440) make the shield segment (110) prefabricated to form a tunnel (120) with expansion sections (121) at both ends, and the platform mold (480) makes the shield segment (110) prefabricated to form a demolding platform (123) connected with the expansion sections (121).

11. The method of prefabricating a shield segment according to claim 10, wherein, The prefabrication method comprises: using the bolt (481) to penetrate the positioning hole (430) and fixedly connecting the core mold fixing member (470) with the connecting hole (482) on the core mold expansion support (460) by the bolt, so as to fix one end of the core mold (420) by the tunnel core mold; the other end of the core mold (420) is fixed by the anchor (130) on the vertical side wall of the anchoring mold (411); wherein the ends of the at least two core molds (420) are fixed by the anchors (130) in an interleaved manner on the opposite vertical side walls of the anchoring mold (411) within the anchoring mold (411) at the bottom of the prefabricated mold (400), forming intersecting tunnels (120) in the anchoring tooth block (142); when the tunnel core mold is disassembled, the ends of the tunnels (120) on both sides in the anchoring tooth block (142) respectively comprise expansion sections (121), and the tunnels (120) in the anchoring tooth block (142) are arranged in an intersecting manner.

12. A method of precasting a shield segment according to claim 10 or 11, characterised in that, The method further comprises: providing at least one socket (510) at one longitudinal end face (550) of the prefabricated mold (400); socket (510) between the shield segments (110) adjacent along the tunnel axis is connected by socket plug, so that the longitudinal end face (550) of the two adjacent shield segments (110) can be connected and fixed.

13. A method of precasting a shield segment according to any one of claims 10 to 12, wherein, The method further comprises: providing at least three hole core mold (460) at the prefabricated mold (400) which penetrates the shield segment (110) along the ring direction, so that the shield segment (110) includes at least three holes (120) which penetrates the two ends of the shield segment (110) along the ring direction, wherein at least one hole (120) is used as a redundant hole (120) for introducing new prestressed steel strand (300) in later maintenance.

14. A method of precasting a shield segment according to any one of claims 10 to 13, wherein, The extension lines of the side edges of the core mold expander bracket (460) intersect to form an expansion angle β, the value range of the expansion angle β is 20-50°, so as to reduce the resistance of the concrete flowing to the side edge of the prefabricated mold (400).

15. A method of precasting a shield segment according to any one of claims 10 to 14, wherein, the angle range of the demolding angle of the platform mold (480) is 10-75°, so that the stress between the demolding platform (123) and the platform mold (480) is not concentrated.

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