A shield tunnel segment channel core mold and prefabricated mold thereof

Abstract

The present invention relates to a tunnel core mold mold for a shield segment and a prefabricated mold thereof; the tunnel core mold mold comprises a core mold bracket and a platform mold, the core mold bracket being detachably connected to the end of the core mold, thereby supporting the core mold in a specified shape; the platform mold being connected to the core mold bracket and arranged at a side position of the prefabricated mold of the shield segment, when a core mold fixing member fixes the core mold bracket and the platform mold by means of bolts penetrating the side of the prefabricated mold, the core mold and the core mold bracket enable the shield segment to be prefabricated into a tunnel having an expansion section, and the platform mold enables the shield segment to be prefabricated into a demoulding platform connected to the expansion section. By providing the tunnel core mold mold, the core mold can be stably fixed while its end forms an expansion section, and the demoulding difficulty is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnels, in particular to a channel core mold mould for a shield tunnel segment and a prefabricated mold thereof. Background Art

[0002] The design of channels within shield segments primarily serves various functional needs within the tunnel, including ventilation, drainage, cable routing, and pipe installation. For example, prestressed steel strands placed within the circumferential channels within the shield segments enhance the structural strength and stability of the segments, improving the tunnel's overall load-bearing capacity and crack resistance. Prestressed steel strands have several key functions within the shield segments: First, by applying prestress, they generate compressive stress within the segments when subjected to external loads, thereby increasing the segments' overall strength and stiffness. This prestress offsets some of the tensile stress caused by external loads, reducing the risk of cracking. Second, they enhance crack resistance. Prestressed steel strands can effectively control crack development within the shield segments, particularly when subjected to uneven tunnel settlement or lateral pressure. Prestressed steel strands limit crack width and length, improving the segments' crack resistance. The rational arrangement of prestressed steel strands ensures the stability of the segments under various loads. Third, it improves bearing capacity. The application of prestressed steel strands can increase the bearing capacity of shield segments, enabling them to withstand greater external loads such as earth and water pressure. Fourth, it improves structural performance. The installation of prestressed steel strands can also improve the overall structural performance of shield segments, such as improving their seismic resistance and deformation resistance. Fifth, it extends service life. The application of prestressed steel strands can reduce damage and degradation of shield segments during use, extending the service life of the tunnel. Anti-corrosion treatment of prestressed steel strands can also improve the durability of the strands, further ensuring the long-term stable operation of the tunnel.

[0003] The casting of shield segments with annular channels is a delicate and technically demanding process that requires precise positioning, size, and shape of the channels while maintaining the quality and structural strength of the segments. The general steps for casting shield segments with annular channels include:

[0004] (1) Install the core mold or mold assembly used to form the annular channel in the steel frame, ensuring that the position and direction of the core mold are correct and firmly fixed.

[0005] (2) Arrange the steel skeleton and core mold together in the mold.

[0006] (3) Install the core mold used to form the annular channel into the mold, ensuring that the position and direction of the core mold are correct and firmly fixed.

[0007] (4) Prepare concrete that meets the requirements and pour it. Pour the mixed concrete evenly into the mold and vibrate the concrete with a vibrator to remove bubbles and ensure that the concrete is dense. During the pouring process, care should be taken to control the pouring speed and thickness of the concrete to avoid poor concrete flow or segregation.

[0008] (5) After the concrete pouring is completed, the surface of the shield segment shall be treated as necessary, such as smoothing and calendering, to ensure that the surface is flat and smooth.

[0009] (6) After the concrete pouring is completed, the shield segments should be properly maintained, such as steam curing, curing agent curing, covering with moisturizing materials, water spray curing, pool curing, etc., to ensure the strength and durability of the concrete.

[0010] (7) After the concrete reaches sufficient strength, the mold is removed and the shield segments are inspected, including the location, size, shape, etc. of the channel, to ensure that the segments meet the design requirements and construction standards.

[0011] A tunnel core is typically a specially designed mold assembly used to form the tunnel's shape and dimensions during concrete pouring. The core's design and material selection must consider factors such as stability, durability, and ease of disassembly during concrete pouring and curing. Common types of tunnel cores include wooden, plastic, metal, rubber, and composite materials. A special type of core is a corrugated pipe, typically made of a flexible material with a corrugated surface structure. Corrugated pipe is suitable as a core for shield segments that require circumferential tunnels, particularly when the tunnel requires a certain degree of flexibility and sealing. Corrugated pipe is relatively simple to install and remove and can accommodate tunnels of varying sizes and shapes. For example, the flexibility of the bellows allows it to accommodate minor deformations during concrete pouring, minimizing damage to the concrete structure. The corrugated structure of the bellows increases the contact area with the concrete, improving the tunnel's sealing and stability.

[0012] Preferably, if the core mold is placed inside the tube body and acts as a support and bracket, then after the mold is removed, the core mold can be removed and reused. If the core mold is used directly to replace the tube body, the core mold is pre-embedded in the concrete to form a channel, becoming an integral part of the prefabricated component and cannot be reused. In this case, the core mold is usually a rigid tube.

[0013] Currently, the channel is prefabricated into an arc shape using a corrugated pipe as a core mold. The channel has the same diameter. When multiple shield segments are spliced together to form a pipe ring, multiple channels are spliced together to form a circular channel. When prestressing is applied by the steel bundles in the channel, the following problems often occur:

[0014] (1) Uneven prestress transfer: The end diameter of the ordinary channel does not change, which may lead to uneven transfer of the prestressed steel strands in the channel, affecting the effective application of prestress.

[0015] (2) When adjacent shield segments are misaligned, the end diameter of the common channel remains unchanged, which may make it difficult to achieve accurate docking of the channel during the misaligned connection, affecting the integrity and sealing of the segment. It also causes difficulties in the construction and operation of the prestressed steel strands in the tunnel. At the misaligned connection, since the diameter of the channel does not change, stress concentration may occur, affecting the structural strength and stability of the segment. During the misaligned construction process, it is necessary to ensure the accurate docking and sealing of the channel, otherwise it may cause water seepage or structural damage.

[0016] Therefore, the channel structure should be optimized. However, optimizing the channel core mold encountered many problems. If the ends of the bellows were simply set to a cone or expanded trumpet shape, it was found that the core mold could not be stably fixed.

[0017] Specifically, in terms of fixation: (1) Fixation is more difficult. The design of the expanded bell mouth increases the difficulty of fixing the bellows in the mold because the bell mouth part may be displaced or deformed during the concrete pouring process. (2) The fixing point is difficult to determine. Additional fixing points or support structures need to be designed to ensure the stable position of the bellows in the mold, which may increase the complexity and cost of the mold. (3) The fixing material is not easy to determine. The fixing material and method need to be able to withstand the pressure and vibration during the concrete pouring process to prevent the bellows from shifting or being damaged.

[0018] In terms of pouring: (1) Concrete flow is obstructed. The expanded bell mouth may hinder the uniform flow of concrete, resulting in uneven distribution of concrete around the hole, affecting the quality and shape of the hole. (2) Due to the change in the shape of the bell mouth, bubbles or gaps may be generated during the concrete pouring process, affecting the density and strength of the hole. (3) Vibration becomes more difficult. During the concrete pouring process, the vibrator may find it difficult to effectively reach the bell mouth, resulting in insufficient concrete density in this area.

[0019] For example, patent document CN114483088A discloses a prestressed steel fiber concrete shield tunnel structure comprising a shield ring and a circumferential prestressing structure. Each shield ring comprises multiple shield segments connected into a ring-shaped integral structure by the circumferential prestressing structure. Circumferential prestressing is applied to each shield segment by the circumferential prestressing structure. The circumferential prestressing structure comprises a circumferential corrugated tube pre-embedded in the shield ring. The shield segments are cast from steel fiber concrete, a multiphase composite material formed by randomly distributed short steel fibers in ordinary concrete. The ducts within the shield segments in this invention are typical ordinary ducts with unchanged diameters. Therefore, when circumferential prestressing is applied, there are problems with uneven prestressing transmission and stress concentration during misalignment.

[0020] Therefore, how to improve the core mold and the channel structure of the channel and overcome the above-mentioned defects at the same time is the technical problem that the present invention hopes to solve.

[0021] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the Invention

[0022] Currently, optimizing the core mold for the channel faces many challenges. For example, simply designing the ends of the bellows into a tapered or flared shape makes it difficult to stabilize the core mold.

[0023] Specifically, in terms of fixation: (1) Fixation becomes more difficult. The expanded bell-mouth design increases the difficulty of fixing the bellows in the mold because the bell-mouth portion may shift or deform during the concrete pouring process. (2) The fixing point is difficult to determine. Additional fixing points or support structures need to be designed to ensure the stable position of the bellows in the mold, which may increase the complexity and cost of the mold. (3) The selection of fixing materials is difficult. The fixing materials and methods need to be able to withstand the pressure and vibration during the concrete pouring process to prevent the bellows from shifting or being damaged.

[0024] In terms of pouring: (1) Concrete flow is obstructed. The expansion of the bell mouth may hinder the uniform flow of concrete, resulting in uneven distribution of concrete around the channel, affecting the quality and shape of the channel. (2) The change in the shape of the bell mouth may cause bubbles or gaps to form during the concrete pouring process, affecting the density and strength of the channel. (3) Vibration becomes more difficult. During the concrete pouring process, the vibrator may find it difficult to effectively reach the bell mouth, resulting in insufficient concrete density in this area.

[0025] In response to the deficiencies of the prior art, the present invention provides, from a first aspect, a core mold mold for a shield segment, comprising a core mold bracket and a platform mold, wherein the core mold bracket is connected to the end of the core mold in a detachable manner, thereby supporting the core mold in a specified shape; the platform mold is connected to the core mold bracket and is arranged on the side of the prefabricated mold of the shield segment, and when the core mold fixing part fixes the core mold bracket and the platform mold by bolts passing through the side of the prefabricated mold, the core mold and the core mold bracket enable the shield segment to be prefabricated into a channel with an expansion section, and the platform mold enables the shield segment to be prefabricated into a demolding platform connected to the expansion section.

[0026] The removable connection allows for the reuse of the channel core mold. The precise design of the core mold support and platform mold ensures the core mold is stably supported in the precast mold, preventing its ends from shifting during the pouring process. This design helps minimize deviations in channel diameter and shape, ensuring precise alignment when the channels are spliced into the pipe ring.

[0027] According to a preferred embodiment, the core mold bracket includes a core mold support bracket and a core mold expansion bracket; the core mold support bracket is a straight column, and is inserted into and fixed at the end of the core mold in a manner matching the diameter size of the core mold; the core mold expansion bracket forms an expansion shape in a manner that the diameter of the axial section gradually expands, and its end with a smaller diameter is connected to the core mold support bracket, so that the end of the channel forms an expansion section with a gradually changing diameter.

[0028] The core mold support bracket's shape shortens the core mold's material length while maintaining the shape of the core mold's ends. This reduces resistance to concrete flow toward the ends during pouring, while also strengthening the core mold's ends and preventing deformation. The core mold expansion bracket's structural design evenly distributes stress when the core mold is subjected to concrete pressure, reducing localized stress concentration and thus preventing twisting or deformation of the core mold.

[0029] According to a preferred embodiment, the inclined edge of the longitudinal section of the platform mold forms a demolding angle with its axis, and the platform mold is installed in a manner that the demolding angle expands toward the side of the prefabricated mold, and the diameter of the platform mold is larger than the diameter of the core mold expansion bracket. When the shield segment is prefabricated, the plane of the demolding platform prefabricated by the platform mold is perpendicular to the circumference of the expansion section.

[0030] The platform mold and core mold expansion bracket are fixed adjacent to each other, so the radial surface of the core mold expansion bracket is not fixed by the concrete pouring. At the same time, because the platform mold and the side of the precast mold are tightly fixed, concrete cannot flow between the platform mold and the precast mold, thus preventing the platform mold from being fixed relative to the shield segment. Therefore, this arrangement ensures smooth demolding of the platform mold and the core mold bracket.

[0031] The draft angle also reduces friction and resistance during demoulding, making demoulding easier and smoother, and improving demoulding efficiency. The draft angle also helps evenly distribute the forces on the mold during concrete pouring. The larger diameter design allows the concrete pressure to be more evenly distributed on the demoulding platform, reducing local stress concentration and thus avoiding deformation or damage to the mold.

[0032] According to a preferred embodiment, the extension lines of the side edges of the core mold expansion bracket intersect to form an expansion angle β. The expansion angle β ranges from 20 to 50 degrees to reduce resistance to concrete flow toward the side edges of the precast mold. Choosing a suitable expansion angle β allows for smoother concrete flow, reduces resistance around the pores, and promotes uniform distribution and filling of the concrete.

[0033] According to a preferred embodiment, the platform mold's draft angle α ranges from 10 to 75°, eliminating stress concentration between the demolding platform and the platform mold. Properly setting the draft angle α also helps improve demolding efficiency. During demolding, an appropriate draft angle allows the demolding platform to more smoothly separate from the mold, reducing friction and resistance during demolding, improving demolding speed and efficiency, and minimizing damage to shield segments.

[0034] According to a preferred embodiment, the precast mold is provided with a groove mold and an anchoring mold. The groove mold is arranged on both sides of the anchoring mold. The groove mold is configured as a convex arc structure to prefabricate the groove. The anchoring mold is recessed relative to the groove mold to form a deep groove. After prefabrication, the deep groove forms the anchoring tooth block of the shield segment. The core mold is fixed in the anchoring mold, forming a cross channel in the anchoring mold. The circumferential prestressing of the segment forms a closed loop, achieving prestressed tension in the ring, and further facilitating more uniform stress in the ring formed by splicing the shield segments.

[0035] The present invention provides a prefabricated mold for a shield segment from a second aspect. A groove mold and an anchoring mold are provided at the bottom of the prefabricated mold. The groove mold is provided on both sides of the anchoring mold. The groove mold is provided with a convex arc structure to prefabricate a groove. The anchoring mold is recessed relative to the groove mold and forms a deep groove, so that the deep groove forms an anchoring tooth block of the shield segment after prefabrication; at least one positioning hole is provided on the side of the prefabricated mold, for the channel core mold mold to pass through the positioning hole and fix one end of the core mold, and the other end of the core mold is fixed to the vertical side wall of the anchoring mold by an anchor; wherein, the channel core mold mold includes a core mold bracket and a platform mold, and the core mold bracket is connected to the end of the core mold in a detachable manner to support the core mold in a specified shape; the platform mold is connected to the core mold bracket and is provided on the side of the prefabricated mold of the shield segment.

[0036] The prefabricated mold of the present invention provides expansion sections at both ends of the channel of the prefabricated shield segment, and the channels in the anchor tooth block are cross-arranged, so that one end of the prestressed steel bundle in the channel can be tensioned in the anchor tooth block.

[0037] According to a preferred embodiment, one end of at least two core molds is fixed to two opposite vertical side walls of the anchoring mold by anchors in a staggered manner in the anchoring mold.

[0038] This design ensures the precise positioning and stability of the core mold during the prefabrication process. This design helps improve the prefabrication accuracy of the shield segment channel and also forms a closed loop of circumferential prestressing in the segment, achieving prestressed tensioning of the ring.

[0039] According to a preferred embodiment, the core mold fixing member securely connects the core mold support and the platform mold by means of bolts extending through positioning holes on the side of the precast mold. The core mold and the core mold support allow the shield segment to be prefabricated with a channel having an expansion section, while the platform mold allows the shield segment to be prefabricated with a demoulding platform that connects to the expansion section. This design allows the core mold and the core mold support to be installed quickly and securely, improving production efficiency.

[0040] According to a preferred embodiment, the core mold bracket includes a core mold support bracket and a core mold expansion bracket; the core mold support bracket is a straight column, and is inserted into and fixed at the end of the core mold in a manner matching the diameter size of the core mold; the core mold expansion bracket forms an expansion shape in a manner that the diameter of the axial section gradually expands, and its end with a smaller diameter is connected to the core mold support bracket, so that the end of the channel forms an expansion section with a gradually changing diameter.

[0041] The combined design of the core mold support bracket and the core mold expansion bracket ensures the precise expansion shape of the channel and improves the structural integrity and functionality of the channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the structure of the core mold of the duct provided by the present invention;

[0043] Figure 2 It is an angle schematic diagram of the core mold support provided by the present invention;

[0044] Figure 3 It is a structural schematic diagram of the platform mold provided by the present invention;

[0045] Figure 4 This is an angled schematic diagram of the core mold expansion stent provided by the present invention;

[0046] Figure 5 It is an enlarged structural schematic diagram of the core mold support provided by the present invention;

[0047] Figure 6This is a schematic structural diagram of a non-porous fixed mold provided by the present invention;

[0048] Figure 7 It is a schematic structural diagram of the shield segments provided by the present invention in a spliced state;

[0049] Figure 8 This is a schematic structural diagram of a duct prefabricated by a core mold support in a spliced state provided by the present invention;

[0050] Figure 9 It is a structural schematic diagram of the standard segment at the anchor end provided by the present invention;

[0051] Figure 10 It is a structural schematic diagram of the prefabricated mold provided by the present invention;

[0052] Figure 11 is an enlarged schematic diagram of the chamfer of the prefabricated mold provided by the present invention;

[0053] Figure 12 It is a side structural diagram of the arrangement of the inner channel of the standard segment at the anchor end provided by the present invention;

[0054] Figure 13 It is a planar structural schematic diagram of the hole arrangement method of the standard pipe segment at the anchor end provided by the present invention.

[0055] Reference Signs List

[0056] 110: Shield segment; 111: Standard segment at anchor end; 112: Standard segment at non-anchor end; 113: Adjacent segment; 114: Capping segment; 120: Hole; 121: Expansion section; 123: Demolding platform; 130: Anchor; 140: Anchor assembly; 141: Groove; 142: Anchor tooth block; 143: Anchor concrete; 300: Prestressed steel tendon; 400: Precast mold; 410 : Groove mold; 411: Anchoring mold; 420: Core mold; 421: Straight line segment; 422: Arc segment; 423: First chamfer; 424: Second chamfer; 430: Positioning hole; 440: Core mold bracket; 450: Core mold supporting bracket; 460: Core mold expansion bracket; 470: Core mold fixing part; 480: Platform mold; 481: Bolt; 482: Connecting hole; 490: Fixed mold without channel. DETAILED DESCRIPTION

[0057] The following is a detailed description with reference to the accompanying drawings.

[0058] Currently, the channel 120, formed by the corrugated tube as the core mold 420, is prefabricated into an arc shape. The channel 120 has a uniform diameter. When multiple shield segments 110 are spliced together to form a pipe ring, the multiple channels 120 are spliced together to form a circular channel 120. When prestressing is applied by the prestressed steel strands 300 within the channel 120, the following problems often arise:

[0059] (1) Uneven prestressing force transmission: The end diameter of the common channel 120 does not change, which may cause uneven transmission of the prestressing steel strand 300 in the channel 120, affecting the effective application of prestressing force.

[0060] (2) When adjacent shield segments 110 are misaligned, the end diameter of the common channel 120 does not change, which may make it difficult to achieve accurate docking of the channel 120 during the misaligned connection, thereby affecting the integrity and sealing of the segment, and also causing difficulties in the construction operation of the prestressed steel bundle 300 in the tunnel. At the misaligned connection, since the diameter of the channel 120 does not change, stress concentration may occur, affecting the structural strength and stability of the segment. During the misaligned construction process, it is necessary to ensure the accurate docking and sealing of the channel 120, otherwise it may cause water seepage or structural damage.

[0061] Therefore, the structure of the channel 120 should be optimized. However, there are many problems in optimizing the core mold 420 of the channel 120. If the two ends of the bellows are simply set to a cone or an expanded trumpet shape, it is found that the core mold 420 cannot be stably fixed.

[0062] Specifically, in terms of fixation: (1) Fixation is more difficult. The design of the expanded bell mouth increases the difficulty of fixing the bellows in the mold because the bell mouth part may be displaced or deformed during the concrete pouring process. (2) The fixing point is difficult to determine. Additional fixing points or support structures need to be designed to ensure the stable position of the bellows in the mold, which may increase the complexity and cost of the mold. (3) The fixing material is not easy to determine. The fixing material and method need to be able to withstand the pressure and vibration during the concrete pouring process to prevent the bellows from shifting or being damaged.

[0063] In terms of pouring: (1) Concrete flow is obstructed. The expanded bell mouth may hinder the uniform flow of concrete, resulting in uneven distribution of concrete around the channel 120, affecting the quality and shape of the channel 120. (2) Due to the change in the shape of the bell mouth, bubbles or gaps may be generated during the concrete pouring process, affecting the density and strength of the channel 120. (3) Vibration becomes more difficult. During the concrete pouring process, the vibrator may have difficulty effectively reaching the bell mouth, resulting in insufficient concrete density in this area.

[0064] In view of the shortcomings of the prior art, the present invention provides a shield tunnel segment channel core mold and a prefabrication mold thereof. The present invention can also provide a shield tunnel segment prefabrication method.

[0065] Example 1

[0066] like Figure 1 As shown, the present invention provides a tunnel core mold mold for a shield segment, comprising a core mold support 440 and a platform mold 480. The core mold support 440 is detachably connected to the end of the core mold 420, thereby supporting the core mold 420 in a specified configuration. The platform mold 480 is connected to the core mold support 440 and is positioned on the side of the precast mold 400 of the shield segment 110. The core mold fixing member 470 securely connects the core mold support 440 and the platform mold 480 by means of bolts 481 penetrating the side of the precast mold 400. In this case, the core mold 420 and the core mold support 440 act together on the shield segment 110 to prefabricate the tunnel 120 having an expansion section 121. At the same time, the platform mold 480 prefabricates the shield segment 110 into a demolding platform 123 that connects to the expansion section 121. The detachable installation method allows the tunnel core mold mold to be reused. The precise design of the core mold support 440 and the platform mold 480 ensures that the core mold 420 is stably supported in the precast mold 400, and its end is not easily displaced during the casting process. This design helps to reduce the diameter and shape deviation of the channel 120, ensuring that the channel 120 can be accurately connected when spliced into a pipe ring.

[0067] like Figure 2 As shown, 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 linear column and is inserted into and fixed to the end of the core mold 420 in a manner that matches the diameter of the core mold 420. The core mold expansion bracket 460 forms an expanded shape by gradually expanding the diameter of the axial cross-section, and its smaller diameter end is connected to the core mold support bracket 450, so that the end of the channel 120 forms an expanded section 121 with a gradually changing diameter.

[0068] The design of the core mold support bracket 450 not only maintains the shape of the core mold 420's ends, shortening the material length and reducing resistance to concrete flow toward the ends during pouring, but also enhances the end strength and prevents deformation. The structural design of the core mold expansion bracket 460 enables the core mold 420 to evenly distribute stress when subjected to concrete pressure, reducing localized stress concentration and thus preventing twisting or deformation of the core mold 420.

[0069] like Figure 3As shown, the inclined edge of the longitudinal section of the platform mold 480 forms a demolding angle with its axis, and the platform mold 480 is installed in a manner that the demolding angle expands toward the side of the prefabricated mold 400, and the diameter of the platform mold 480 is larger than the diameter of the core mold expansion bracket 460. When the shield segment 110 is prefabricated, the plane of the demolding platform 123 prefabricated by the platform mold 480 is perpendicular to the circumference of the expansion section 121.

[0070] The platform mold 480 and the core mold expansion bracket 460 are fixed adjacent to each other so that the radial surface of the core mold expansion bracket 460 is not fixed by the concrete pouring. At the same time, because the platform mold 480 is tightly fixed to the side of the precast mold 400, concrete cannot flow between the platform mold 480 and the precast mold 400, thereby preventing the platform mold 480 from being fixed relative to the shield segment 110. Therefore, this arrangement ensures smooth demolding of the platform mold 480 and the core mold bracket 440.

[0071] The draft angle also reduces friction and resistance during demolding, making demolding easier and smoother, improving demolding efficiency while minimizing damage to shield segments. The draft angle also helps evenly distribute the forces applied to the mold during concrete pouring. The larger diameter design allows for a more even distribution of concrete pressure on the demolding platform 123, reducing localized stress concentration and thus preventing deformation or damage to the mold.

[0072] like Figure 2 and Figure 4 As shown, the extension lines of the side edges of the core mold expansion bracket 460 intersect to form an expansion angle β, which ranges from 20 to 50 degrees to reduce the resistance of concrete to the side edges of the precast mold 400. Proper selection of the expansion angle β allows for smoother concrete flow, reduces resistance around the duct 120, and facilitates uniform distribution and filling of the concrete.

[0073] Preferably, the expansion angle β is further preferably between 25 and 35 degrees. Further preferably, the expansion angle β is 30 degrees. Setting the expansion angle β to 30 degrees facilitates the removal of the core mold expansion bracket 460 from the expansion section 121 of the channel 120. If the length of the expansion section 121 is fixed, if the expansion angle β is too large, the sidewalls of the expansion section 121 at the end of the precast segment will lose their guiding function. If misalignment occurs, the prestressed steel strand 300 cannot be smoothly guided into the channel 120. Wall thickness is related to stress resistance. Thinner walls reduce stress resistance, while thicker walls increase stress resistance. Furthermore, the expansion angle β is also related to wall thickness. The size of the expansion angle β causes a corresponding change in the hole diameter of the expansion section 121 at the end of the precast segment, thereby causing a corresponding change in the wall thickness between the side of the precast segment and the hole. If the expansion angle β is too large, the hole diameter of the expansion section 121 at the end of the precast segment increases, resulting in a thinner wall. Therefore, the expansion angle β cannot be set arbitrarily. If the expansion angle β is too small, the friction between the prestressed steel strand 300 and the borehole wall of the expansion section 121 will increase when misalignment occurs, failing to effectively reduce the resistance of the prestressed steel strand 300 to movement within the expansion section 121. Therefore, the present invention sets the expansion angle β to 30°, ensuring that the borehole wall thickness of the expansion section 121 is sufficient to withstand stress, while also facilitating the core mold expansion bracket 460's removal from the expansion section 121. Furthermore, the resistance between the prestressed steel strand 300 and the borehole wall at the end of the prefabricated segment is also reduced.

[0074] like Figure 3 and Figure 5 As shown, the demoulding angle α of the platform mold 480 ranges from 10 to 75 degrees, so that the stress between the demoulding platform 123 and the platform mold 480 is not concentrated. Further preferably, the demoulding angle α ranges from 15 to 65 degrees. Further preferably, the demoulding angle α is 20 degrees. The reasonable setting of the demoulding angle α also helps to improve the demoulding efficiency. During the demoulding process, the appropriate demoulding angle α enables the demoulding platform 123 to be separated from the mold more smoothly, reducing the friction and resistance during the demoulding process, improving the speed and efficiency of demoulding, and not easily causing damage to the shield segment.

[0075] If the core mold expansion bracket 460 is directly connected to the end of the precast mold 400 only by bolts 481, not only will concrete easily flow into the gap, but without the platform mold 480 to disperse the force, the pressure of the concrete may cause stress concentration at the contact point between the core mold expansion bracket 460 and the precast mold 400, which may cause local deformation or damage to the core mold expansion bracket 460 or the precast mold 400. Concrete may directly impact the end of the precast mold 400, causing the concrete surface to be uneven or form defects. During the pouring process, the direct contact between the concrete, the core mold expansion bracket 460 and the precast mold 400 may generate more vibration and noise.

[0076] The functions of platform mold 480 include two aspects:

[0077] First, to fill the gap between the core mold expansion bracket 460 and the precast mold 400, preventing concrete from flowing into the gap and forming an obstacle on the surface of the core mold expansion bracket 460 that would hinder demolding, the diameter of the platform mold 480 is larger than the maximum diameter of the core mold expansion bracket 460. The platform mold 480 can improve the sealing performance between the core mold expansion bracket 460 and the end of the precast mold 400, especially when there may be slight unevenness between the core mold expansion bracket 460 and the end of the precast mold 400. The platform mold 480 can fill these unevenness and prevent air or concrete leakage.

[0078] Second, it facilitates the securement of the core mold expansion bracket 460. The shape and size of the core mold expansion bracket 460 affect the path and speed of concrete flow. Due to the expansion angle β, the concrete near the core mold expansion bracket 460 flows along an inclined profile, and the direction of the force changes with the change in the expansion profile. As the concrete flows from the surface of the core mold 420 toward the surface of the core mold expansion bracket 460, the direction of the force gradually shifts from vertical to horizontal, resulting in uneven stress distribution. In this case, if the platform mold 480 is positioned between the core mold expansion bracket 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 bracket 460 and the precast mold 400, reducing localized stress concentrations. The platform mold 480 also absorbs the impact force during concrete pouring, preventing concrete from directly impacting the connection between the core mold expansion bracket 460 and the precast mold 400, thereby reducing the risk of damage. The platform mold 480 also reduces direct contact between the core mold expansion bracket 460 and the precast mold 400, thereby reducing vibration and noise.

[0079] Third, it facilitates demolding. The platform mold 480 provides an additional contact surface, making it easier to separate the precast segment from the precast mold 400. In particular, when the platform mold 480 is tilted on all sides, forming a draft angle α in cross section, the larger surface area of the platform mold 480 facilitates demolding from the end of the precast segment. Because the gap between the core mold expansion bracket 460 and the platform mold 480 is obstructed only by, or even absent of, concrete, resistance to demolding the core mold expansion bracket 460 is reduced, while also minimizing wear on the core mold expansion bracket 460 and extending its service life.

[0080] like Figure 10 As shown, a groove mold 410 and an anchoring mold 411 are provided in the prefabricated mold 400. The groove mold 410 is provided on both sides of the anchoring mold 411. The groove mold 410 is provided in a convex arc 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. The core mold 420 is fixed in the anchoring mold 411, so that a cross channel 120 is formed in the anchoring mold 411. The circumferential prestress of the segment forms a closed loop, realizing prestressed tensioning of the pipe ring, which is more conducive to making the stress of the pipe ring formed by splicing the shield segments 110 more uniform.

[0081] like Figure 9 As shown, the anchor assembly 140 includes a groove 141 and an anchor tooth block 142. A hole 120 is also provided in the anchor tooth block 142. The groove 141 is provided on the side of the anchor tooth block 142, and the extension direction of the groove 141 is perpendicular to the central axis of the prefabricated segment. In the prefabricated anchor assembly 140, the tensioning end of the prestressed steel strand 300 is sealed by the anchor concrete 143, so that the groove 141, the anchor tooth block 142 and the anchor concrete 143 together form a force-bearing structure. This ensures that the tensioning force of the prestressed steel strand 300 can be effectively transmitted to the prestressed shield segment 110, thereby improving the overall stability and tensile strength of the structure.

[0082] like Figure 11 As shown, the arcuate profile of the groove mold 410 includes a straight line segment 421 and an arc segment 422. The straight line segment 421 and the arc segment 422 form a natural transition. A second chamfer 424 is provided at the junction of the groove mold 410 and the anchor mold 411. A first chamfer 423 is provided at the bend between the vertical sidewall and the bottom of the anchor mold 411.

[0083] Preferably, the groove mold 410 and the anchoring mold 411 are formed by welding two steel plates, or by bending a single steel plate. Preferably, the first chamfer 423 is an inner fillet. The first chamfer 423 cannot be less than 10 mm. The second chamfer 424 is an outer fillet. The second chamfer 424 has a minimum of 6 mm. The first chamfer 423 and the second chamfer 424 are arranged in opposite directions.

[0084] like Figure 6 As shown, when the channels 120 are not required in the precast segments, a non-channel fixed mold 490 is installed at the positioning holes 430 of the precast mold 400 to block the positioning holes 430 and prevent concrete from flowing out of the positioning holes 430 during pouring. The non-channel fixed mold 490 differs from the platform mold 480 in that it is a circular piece and does not have a draft angle α in its cross-section when it is longitudinally arranged.

[0085] Example 2

[0086] This embodiment is a further improvement of embodiment 1, and repeated contents will not be repeated here.

[0087] The present invention provides a prefabricated mold 400 for a shield segment, such as Figure 10 As shown, the bottom of the precast mold 400 is provided with a groove mold 410 and an anchor mold 411. The groove mold 410 is arranged on both sides of the anchor mold 411. The groove mold 410 is arranged in a convex arc structure to prefabricate the groove 141. The anchor mold 411 is recessed relative to the groove mold 410 to form a deep groove. After prefabrication, the deep groove forms the anchor tooth block 142 of the shield segment 110. After prefabrication, the groove mold 410 forms the groove 141 of the shield segment 110.

[0088] like Figure 10 As shown, at least one positioning hole 430 is provided on the side of the prefabricated mold 400. Figure 2 and Figure 10 As shown, the bolt 481 passes through the positioning hole 430 and fixes the core mold fixing part 470 to the connecting hole 482 on the core mold expansion bracket 460, thereby fixing one end of the core mold 420 through the channel core mold 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 channel core mold mold includes a core mold bracket 440 and a platform mold 480. The core mold bracket 440 is connected to the end of the core mold 420 in a detachable manner, thereby supporting the core mold 420 in a specified shape. The platform mold 480 is connected to the core mold bracket 440 and is set at the side position of the prefabricated mold 400 of the shield segment 110.

[0089] The prefabricated mold 400 of the present invention provides expansion sections 121 at both ends of the channel 120 of the prefabricated shield segment 110. At the same time, the channels 120 in the anchoring tooth block 142 are cross-arranged, so that one end of the prestressed steel bundle 300 in the channel 120 can be tensioned in the anchoring tooth block 142.

[0090] like Figure 13 As shown, one end of at least two core molds 420 is fixed to two opposite vertical sidewalls of the anchor mold 411 by anchors 130 in a staggered manner within the anchor mold 411, forming intersecting channels 120 within the anchor tooth block 142. A non-intersecting channel 120 also exists within the anchor end standard segment 111. This non-intersecting channel 120 forms a prestressed channel in the circumferential direction of the shield tunnel. In the circumferential direction, the non-intersecting channel 120 is parallel to, or nearly parallel to, the intersecting channel 120.

[0091] like Figure 12 and Figure 13 As shown, after the prefabricated segment is finalized, the core mold 420 is not disassembled and forms a part of the channel 120. When the channel core mold is disassembled, the ends of the channel 120 on both sides of the anchor tooth block 142 respectively include expansion sections 121. In this part, an anchor 130 is set in the anchor tooth block 142. After the prestressed steel bundle 300 is inserted into the channel 120, the anchor 130 is used to tension the prestressed steel bundle 300 to form sufficient prestress. Such a design ensures the precise position and stability of the core mold 420 during the prefabrication process. This design helps to improve the prefabrication accuracy of the channel 120 of the shield segment 110, ensures that the channel core mold can accurately pass through the positioning hole 430 and fix the core mold 420, and also enables the prestressed steel bundle 300 to form a closed loop in the circumferential prestress of the segment, realizing the prestressed tensioning of the pipe ring, thereby improving the quality and consistency of the prefabricated segment.

[0092] like Figure 1 As shown, the core mold fixing member 470 securely connects the core mold support 440 and the platform mold 480 by means of bolts 481 penetrating the positioning holes 430 on the side of the prefabricated mold 400. The core mold 420 and the core mold support 440 allow the shield segment 110 to be prefabricated into a channel 120 having an expansion section 121, and the platform mold 480 allows the shield segment 110 to be prefabricated into a demoulding platform 123 connected to the expansion section 121. This design allows the core mold 420 and the core mold support 440 to be quickly and securely installed, thereby improving production efficiency.

[0093] like Figure 1As shown, 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 linear column and is inserted into and fixed to the end of the core mold 420 in a manner that matches the diameter of the core mold 420. The core mold expansion bracket 460 forms an expanded shape by gradually expanding the diameter of the axial cross-section, and its smaller diameter end is connected to the core mold support bracket 450, so that the end of the channel 120 forms an expanded section 121 with a gradually changing diameter.

[0094] The combined design of the core mold support bracket 450 and the core mold expansion bracket 460 ensures the precise expansion shape of the channel 120 and improves the structural integrity and functionality of the channel 120.

[0095] Example 3

[0096] This embodiment provides a prefabricated pipe segment made from the molds of Example 1 and Example 2.

[0097] like Figure 7 As shown, the shield segment 110 is composed of an anchor end standard segment 111, a non-anchor end standard segment 112, an adjacent segment 113 and a capping segment 114. Among them, the anchor end standard segment 111 is equipped with an anchor assembly 140. The non-anchor end standard segment 112 is located between the two anchor end standard segments 111. The anchor end standard segment 111 is connected to the adjacent segment 113, and the adjacent segment 113 is connected to the capping segment 114. A channel 120 is designed inside each shield segment 110. Figure 8 As shown, each shield segment 110 has at least one channel 120, and expansion sections 121 are provided at both ends of the channel 120. Ideally, the number of channels 120 in a shield segment 110 should be two or four. When multiple shield segments 110 are assembled into a pipe ring, the channels 120 inside them will also be connected one after another to form a continuous circular channel, such as Figure 8 For example, the diameter of the channel 120 in the non-expanded portion is 56 mm inner diameter and 60 mm outer diameter. Figure 7 It can be seen that the prestressed steel strands 300 pass through the circular holes 120 and are tensioned at the anchoring assemblies 140 , thereby applying prestress to each shield segment 110 .

[0098] The anchor end standard segment 111, the non-anchor end standard segment 112, the adjacent segment 113, and the capping segment 114 each have their own structural characteristics. For example, the center angles of the anchor end standard segment 111 and the non-anchor end standard segment 112 are both set between 67.3 and 67.5 degrees, the center angle of the adjacent segment 113 is also within this range, and the center angle of the capping segment 114 is set between 22.3 and 22.5 degrees. Figure 7As shown, 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.

[0099] This design shifts the center of gravity of the prestressed shield tunnel away from its geometric center, reducing the impact of internal bending forces on the segments. This improves the tunnel's resistance to bending deformation and extends its service life. Furthermore, adjusting the eccentricity effectively reduces the internal bending forces of the shield segments 110, significantly reducing the amount of steel reinforcement required and thus lowering project costs. Typically, the weight of each ring is reduced from approximately 1 ton to approximately 600 kg, while shield segments using steel fiber reinforced concrete can be further reduced to approximately 300 kg.

[0100] like Figure 7 and 9 As shown, the anchoring end standard segment 111 is preset with an anchoring assembly 140, and the end faces of its two ends 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 an anchoring assembly 140. Their end faces are also parallel to the central axis of the pipe ring, but the two end faces of the capping segment 114 are relatively inclined. The structure of the adjacent segment 113 matches the capping segment 114. The end face of its first end is parallel to the central axis of the pipe ring, which enables the adjacent segment 113 to be assembled with the anchoring end standard segment 111; while the end face of the second end is relatively inclined with respect to the central axis of the pipe ring, and the inclination angle is consistent with the inclination angle of the end of the capping segment 114, which in turn enables the adjacent segment 113 to be assembled with the capping segment 114.

[0101] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and fall within the scope of protection of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute a limitation on the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "preferably" and "according to a preferred embodiment", which means that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept.

Claims

1. A tunnel core mold for a shield segment, characterized in that: It includes a core mold support (440) and a platform mold (480), The core mold support (440) includes a core mold support support (450) in the form of a straight column and a core mold expansion support (460) formed into an expansion shape by gradually expanding the diameter of the axial section. The core mold support support (450) is detachably inserted into and fixed to the end of the core mold (420) in a manner matching the diameter size of the core mold (420), thereby supporting the core mold (420) in a specified shape. The platform mold (480) is connected to the core mold support (440) and is arranged on the side of the prefabricated mold (400) of the shield segment (110). When the core mold fixing member (470) is fixedly connected to the core mold support (440) and the platform mold (480) by means of bolts (481) passing through the side of the prefabricated mold (400), the core mold (420) and the core mold support (440) enable the shield segment (110) to be prefabricated into a channel (120) having an expansion section (121), and the platform mold (480) enables the shield segment (110) to be prefabricated into a demoulding platform (123) connected to the expansion section (121).

2. The shield segment channel core mold according to claim 1, characterized in that: The end with a smaller diameter of the core mold expansion bracket (460) is connected to the core mold support bracket (450), so that the end of the channel (120) forms an expansion section (121) with a gradually changing diameter.

3. The shield segment channel core mold according to claim 1 or 2, characterized in that: The inclined side of the longitudinal section of the platform mold (480) forms a demoulding angle with its axis, The platform mold (480) is installed in a manner such that the demoulding angle expands toward the side of the prefabricated mold (400), and the diameter of the platform mold (480) is larger than the diameter of the core mold expansion bracket (460). When the shield segment (110) is prefabricated, the plane of the demoulding platform (123) prefabricated by the platform mold (480) is perpendicular to the circumference of the expansion section (121).

4. The shield segment channel core mold according to claim 2, characterized in that: The extension lines of the side edges of the core mold expansion bracket (460) intersect to form an expansion angle β, The expansion angle β has a value range of 20 to 50 degrees, so as to reduce the resistance of concrete flowing to the side of the prefabricated mold (400).

5. The shield segment channel core mold according to claim 1, characterized in that: The demoulding angle of the platform mold (480) ranges from 10 to 75 degrees, so that stress between the demoulding platform (123) and the platform mold (480) is not concentrated.

6. The shield segment channel core mold according to claim 1, characterized in that: 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), and the groove mold (410) is arranged in a convex arc structure to prefabricate the groove (141). The anchoring mold (411) is recessed relative to the groove mold (410) to form a deep groove, so that the deep groove forms an anchoring tooth block (142) of the shield segment (110) after prefabrication.

7. A prefabricated mold for a shield segment, characterized in that: 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), and the groove mold (410) is arranged in a convex arc structure to prefabricate the groove (141). The anchoring mold (411) is recessed relative to the groove mold (410) to form a deep groove, so that the deep groove forms an anchoring tooth block (142) of the shield segment (110) after prefabrication; At least one positioning hole (430) is provided on the side of the prefabricated mold (400), for the core mold to pass through the positioning hole (430) and fix one end of the core mold (420). The other end of the core mold (420) is fixed to the vertical side wall of the anchoring mold (411) by an anchor (130); The tunnel core mold mold includes a core mold bracket (440) and a platform mold (480), wherein the core mold bracket (440) includes a core mold support bracket (450) in the form of a straight column and a core mold expansion bracket (460) formed into an expansion shape by gradually expanding the diameter of the axial section, and the core mold support bracket (450) is detachably inserted into and fixed to the end of the core mold (420) in a manner matching the diameter size of the core mold (420), thereby supporting the core mold (420) in a specified shape; the platform mold (480) is connected to the core mold bracket (440) and is arranged on the side of the prefabricated mold (400) of the shield segment (110).

8. The prefabricated mold for shield segments according to claim 7, characterized in that: One end of at least two core molds (420) is fixed in a staggered manner in the anchoring mold (411) by anchors (130) to two opposite vertical side walls of the anchoring mold (411).

9. The prefabricated mold for shield segments according to claim 7 or 8, characterized in that: The core mold fixing member (470) is fixedly connected to the core mold support (440) and the platform mold (480) by means of a bolt (481) penetrating the positioning hole (430) on the side of the prefabricated mold (400). The core mold (420) and the core mold support (440) enable the shield segment (110) to be prefabricated into a channel (120) having an expansion section (121), and the platform mold (480) enables the shield segment (110) to be prefabricated into a demoulding platform (123) connected to the expansion section (121).

10. The prefabricated mold for shield segments according to claim 7, characterized in that: The end with a smaller diameter of the core mold expansion bracket (460) is connected to the core mold support bracket (450), so that the end of the channel (120) forms an expansion section (121) with a gradually changing diameter.

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