Prefabricating method of fabricated inverted arch precast block for single track railway tunnel

Abstract

The invention provides a prefabricating method of an assembly type inverted arch precast block for a single-track railway tunnel. The prefabricating method comprises the following steps that a bottom formwork, a side formwork, an inner side formwork and an inverted arch steel reinforcement framework are manufactured; the inverted arch steel reinforcement framework is sequentially spliced with the bottom formwork, the side formworks and the inner side formworks to form a prototype mold; installing an embedded part in the prototype mold to form a fabricated inverted arch mold; and after concrete is poured into the fabricated inverted arch mold, vibration and maintenance are conducted, and the fabricated inverted arch mold is obtained. According to the prefabrication method of the fabricated inverted arch prefabricated block, the prefabricated part which is larger in weight, more complex in structure and larger in size can be rapidly prefabricated.

Description

Technical Field

[0001] The present invention belongs to the technical field of prefabricated construction, and specifically relates to a prefabrication method for prefabricated invert blocks for single-track railway tunnels. Background Art

[0002] The prefabrication method of prefabricated invert blocks is an advanced tunnel construction technology. It significantly improves the efficiency, quality, and safety of tunnel construction through factory prefabrication and on-site rapid assembly. Compared with traditional in-situ casting technology, by standardizing the production of prefabricated components in the factory and synchronizing it with tunnel excavation, the construction period is greatly shortened, and the construction efficiency is significantly improved. At the same time, when standardizing production in the factory, the high-precision steel molds and automated vibration technology in this environment make the discreteness of concrete strength much lower than that of the in-situ casting process, resulting in more excellent project quality.

[0003] However, the prefabrication methods of prefabricated invert blocks in the existing technology are difficult to prefabricate large-weight and large-size invert precast blocks. This is because large-size components have a large self-weight, which makes it easy to generate large bending moments due to the cantilever effect during hoisting and installation, resulting in local cracking or deformation. Moreover, for large-size and large-weight precast components, the corresponding mold size is also larger. The larger the mold size, the more prone it is to deformation during the concrete pouring and vibration process, resulting in geometric dimension deviation of the precast block and affecting the assembly accuracy. In addition, the shrinkage stress of large-volume concrete after hardening is large, which may cause the mold to be stuck, increasing the risk of demolding. Additionally, for ultra-long and ultra-wide molds, the requirements for processing accuracy are also high, and it is easy to leak slurry at the mold joints, affecting the surface quality of the precast components.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The first object of the present invention is to provide a prefabrication method for prefabricated invert blocks for single-track railway tunnels. Through a prefabricated invert mold with high precision and good structural quality provided by the present invention, a complete large-size and large-weight prefabricated invert block can be quickly prefabricated, thereby reducing the on-site assembly time of multiple small components, reducing the bolt connection or grouting operation time, reducing the risk of water leakage, and improving the seismic resistance and long-term bearing performance.

[0006] To achieve the above object of the present invention, the following technical solutions are specifically adopted: A prefabrication method for prefabricated invert blocks for single-track railway tunnels, comprising the following steps: Manufacture a bottom formwork, side formworks, inner formwork, and invert steel bar skeleton respectively; Splice the invert steel bar skeleton with the bottom formwork, side formworks, and inner formwork in sequence to form a prototype mold; Subsequently, embedded parts are installed in the prototype mold to form an assembled inverted arch mold; Pour concrete into the assembled inverted arch mold and then vibrate and cure it to obtain the finished product.

[0007] Preferably, as a further specific implementation manner, the side formwork includes a formwork main body and a moving support, and the formwork main body and the moving support are fixedly connected by bolts.

[0008] Preferably, as a further specific implementation manner, the prefabrication process of the inverted arch steel bar framework is as follows: Process the steel bars to respectively obtain a plurality of main bars, a plurality of distribution bars and a plurality of stirrups, wherein the main bars include straight bars, arc-shaped bent bars and special-shaped bent bars; Subsequently, bind the arc-shaped bent bars, straight bars, distribution bars and stirrups in sequence according to the steel bar spacing of 10 - 20 cm to obtain the inverted arch steel bar framework.

[0009] Preferably, as a further specific implementation manner, the splicing process of the mold prototype is as follows: A concrete prefabrication and assembly platform, with longitudinal slide rails embedded in the assembly platform; Lift the bottom formwork and place it on the assembly platform, and then fixedly connect the triangular fixing frames on both sides of the bottom formwork to the slide rails; After the fixation is completed, lift the side formwork, respectively fixedly connect the formwork main body to both sides of the bottom formwork, and then lift the moving support and place it on the slide rail to connect the moving support to the slide rail to form a prototype frame; Subsequently, apply protective layer cushion blocks under the inverted arch steel bar framework, lift the inverted arch steel bar framework and move it above the prototype frame and lower it, adjust the thickness of the protective layer cushion blocks, and the assembly is completed.

[0010] Preferably, as a further specific implementation manner, the thickness of the protective layer cushion block is 5 cm.

[0011] Preferably, as a further specific implementation manner, the steps of installing the embedded parts are as follows: Embed a 50 mm PVC pipe in the formwork tensioning hole groove reserved longitudinally on the side formwork; Subsequently, use a rubber rod to reserve an inverted arch rebar planting hole channel in the prototype mold; Subsequently, reserve a grouting hole at the top of the prototype mold; When the concrete strength reaches 75% of the design strength, pull out the PVC pipe and the rubber rod.

[0012] Preferably, as a further specific implementation manner, the rubber rod is conical, thick at the top and thin at the bottom, gradually tapering from top to bottom.

[0013] Preferably, as a further specific embodiment, the inner diameter of the top of the rubber rod is 30 mm, and the inner diameter of the bottom is 25 mm.

[0014] Preferably, as a further specific embodiment, the grouting hole includes a grouting pipe, a casing, a screw cap and a check valve, and a sealing ring is provided at the connection part of the screw cap and the grouting pipe and between the grouting pipe and the casing respectively.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a prefabrication method for prefabricated inverted arch blocks for single-track railway tunnels. Through the prefabrication mold for prefabricated inverted arches with high precision and good structural quality provided by the present invention, a complete large-size and large-weight prefabricated inverted arch block can be quickly prefabricated, thereby reducing the on-site assembly time of multiple small components, reducing the bolt connection or grouting operation time, reducing the risk of water leakage, and improving the seismic resistance and long-term bearing performance. Description of the Drawings

[0016] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0017] Figure 1 It is a structural diagram of straight bars, arc-shaped bent bars, special-shaped bent bars, distribution bars and stirrups in the present invention, where N1 and N2 are straight bars, N3 and N4 are arc-shaped bent bars, N5-N8 are special-shaped bent bars, N9 is a distribution bar, and N 10 -N 12 are stirrups; Figure 2 It is a structural diagram of the side formwork in the prefabrication method of the present invention; Figure 3 It is a structural diagram of the bottom formwork in the prefabrication method of the present invention; Figure 4 It is a side view of the prefabricated inverted arch mold in the present invention. Detailed Embodiments

[0018] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as a limitation of the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0019] In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below.

[0020] Example 1 In this embodiment, the main construction site is located at the playground of Berlin Junior High School at the entrance of Yaopo Village Tunnel. It is surrounded by fully enclosed enclosures, the site road has a 30cmC30 full concrete hardened surface, and the transportation route is a gentle uphill slope from the entrance of the prefabrication site to the inverted arch surface of the Yaopo Village Tunnel entrance, with a length of about 50m and a slope of 3.2%. The site is open, which is convenient for the installation and disassembly of large machinery, and the transportation distance is short and the transportation conditions are good. There are no buried pipelines and cables underground within the walking and lifting range of the tooling. A 20cm×20cm brick mortar powder rectangular drainage ditch is set around the site to discharge the water for maintenance and cleaning in the site; Above the outer side of the enclosure surrounding the site is an overhead high-voltage line for Berlin Junior High School, which is about 5m above the ground and has no impact on the transportation of prefabricated blocks and the installation of assembly machines in the site. A 250KVA transformer is installed on the right side of the Yaopo Village Tunnel, 40m away from the tunnel entrance. The electricity is introduced from the transformer to the primary distribution box (distribution room) of the prefabrication site through overhead lines, and then distributed to the secondary distribution box through cables to supply electricity for living and production. All power lines in the prefabrication site are buried underground, and three-level leakage protection is set up. Leakage protectors are installed in the distribution box and switch box to ensure the safety of electricity use; The assembled invert arch assembly machine is assembled at the site at the tunnel entrance. The temporary parts stacking site is set up in the prefabrication plant, and the 50t crane is used for lifting construction. The specific prefabrication process of the prefabricated inverted arch block is as follows: (1) Specific parameters of the invert precast block There are 98 prefabricated inverts in total, cast with C40 concrete, environmental grades H1, L1, T2, Y2, initial slump 190mm, slump 185 after 30min of parking, slump 180 after 60min of parking, the bottom of the prefabricated invert is an arc structure, length × width × height = 5.744 × 1.5 × 1.334m, single weight 16.12 tons, prefabricated blocks have 7 embedded parts that can be used for hoisting, of which 4 embedded parts that also serve as grouting holes are embedded at the top of the structure. To meet the requirements of production hoisting, transportation and stacking hoisting, 3 are embedded at the bottom for demoulding, and 2 blocks are assembled each time as a cycle. Prefabricated lining blocks need to be made in high-precision steel templates, and the allowable error for the production of a single prefabricated block is: Length: ±2.0mm Width, thickness: ±1.0mm Longitudinal and circumferential flatness: 0-2mm Tolerance of mortise and tenon dimensions: ±1.0mm Bolt and locating pin hole center distance deviation: ±1.0mm; The prefabrication process of the assembled inverted arch precast block provided by the present invention is as follows: formwork cleaning → formwork positioning → release agent brushing → steel bar processing → steel bar binding jig forming → steel bar cage inspection and acceptance → steel bar cage entering the formwork → embedded part installation → protective layer positioning → concrete production → concrete inspection → concrete pouring → vibration forming → concrete finishing → watering maintenance → side form removal and marking → semi-finished product inspection → spray maintenance → inverted arch block storage → precast block transportation; (2) Construction method S1: Preparation before construction 1) All steel bars used for precast blocks are processed and produced by the No. 2 steel bar processing factory and transported to the precast yard by dump trucks. All operating procedure signs in the precast yard are complete, and the site drainage is smooth, meeting the requirements for precast block production. There are areas for stacking semi-finished steel bars, precast block production areas, precast block storage areas, vehicle transportation and loading and unloading operation areas, etc. The processing yard is managed in a closed manner, and the storage area, processing area, and semi-finished product area are reasonably arranged, with obvious signs and nameplates. Steel bars are stacked separately according to different specifications, supported by steel welded brackets, more than 30 cm above the ground, and ensuring that the steel bars do not deform. Mark their model, specification, length, number and other parameters to prevent misusage. Various semi-finished steel bars are marked according to their inspection status and results, usage parts, etc., and the signboards are hung on iron racks at eye-catching places; 2) The semi-finished steel bars entering the site are stored in an orderly manner, with rainproof, rust-proof, and moisture-proof measures in place, and the support height is not less than 30 cm. Different types of steel bars are placed in separate areas, and chaotic placement is prohibited; 3) Familiarize with the design drawings and specifications of the precast inverted arch, and detect the appearance quality and tests of the steel bars entering the site. The steel bar detection is the responsibility of the project department's laboratory; 4) The equipment, formwork, semi-finished steel bars, and personnel entering the site all meet the construction requirements, and the special operation personnel (such as welders, electricians, crane operators, etc.) have complete certificates; S2: Prefabricate the bottom formwork, side formwork, inner formwork and inverted arch steel bar skeleton The preparation process of the inverted arch steel bar skeleton is as follows: 1) Process the steel bars. All steel bars are processed centrally in the steel bar processing area and then transported to the precast yard by dump trucks. After adjusting the binding spacing to 10 - 20 cm on the binding jig, bind the precast inverted arch steel bar skeleton; When processing steel bars, strictly make them according to the on-site steel bar large-scale drawing to ensure that the processed dimensions of the steel bars meet the requirements of the design drawings and specifications. After the project department's engineering and technical personnel draw the steel bar large-scale drawing according to the design drawings, make a signboard for the steel bar large-scale drawing and hang it in the steel bar processing factory; 2) Cut the steel bars strictly according to the drawings when cutting. Consider the elongation value during bending when cutting the steel bars. When cutting the steel bars, the required cutting length can be measured on the work platform, and then positioned with wooden boards to ensure accurate cutting. Use a numerical control hoop bender for steel bar bending.

[0021] 3) Gas welding or spot welding is strictly prohibited for steel bar cutting. For special parts where a cutting machine cannot be used, a cold saw is used for cutting.

[0022] 4) After the steel bars are cut, processed and formed, they are stacked neatly. The semi-finished steel bars are hung with identification plates indicating the using parts, types of steel bars, lengths, etc.

[0023] 5) Both the raw materials and semi-finished products of steel bars shall be supported. The supporting height shall not be less than 30 cm. When they need to be placed outdoors, all raw materials and semi-finished products shall be lifted and covered.

[0024] 6) During construction, if there is a conflict in steel bars, the position is allowed to be adjusted appropriately, but the concrete cover thickness shall be ensured; Among them, in the inverted arch precast blocks prepared in this embodiment, after the steel bars are processed, a plurality of main bars, a plurality of distribution bars and a plurality of stirrups are respectively made. The main bars include straight bars, arc-shaped bent bars and special-shaped bent bars. The total types of steel bars can be divided into N1 - N12. The specific steel bar pattern diagrams are as Figure 1 shown, and the specific quantity and parameters of the steel bars are shown in Table 1 below;

[0025] As Figure 1 shown, the specific binding process of the inverted arch steel bar framework: After adjusting the binding spacing to 10 - 20 cm on the binding jig, first bind the arc-shaped bent bars N3 and N4 to form the inverted arch prototype. Then, on the inverted arch prototype, bind the straight bars, distribution bars and stirrups according to the drawings respectively to obtain the inverted arch steel bar framework; Among them, the preparation processes of the bottom formwork, side formwork and inner formwork are as follows: S1: Preparation before preparation When designing the formwork, fully consider the number of times the formwork is reused, appropriately increase the stiffness of the formwork, and ensure that the deformation of the formwork during use meets the specification requirements. The processing and production of the formwork are carried out strictly according to the design drawings. The processed formwork surface is flat, the joints between the plates are tight and there is no leakage of slurry, ensuring the beauty of the exposed surface of the structure and the smoothness of the lines. The formwork tie rods must have a sufficient safety factor; In this embodiment, the formwork adopts large-sized standardized steel formwork newly processed by a designated manufacturer, with 8 sets of bottom formwork and 2 sets of side formwork. The surface of the steel formwork is rolled with a δ = 5.5 mm steel plate, the frame is δ = 12 mm × 120 mm, the transverse ribs are [12#, the back ribs are [12#, the formwork connection flange holes are Φ22 mm long holes, the side formwork track support is 250a I-beam, and the track is 50*50 mm angle iron, so that the inverted arch is evenly stressed on the entire ground in the vertical direction; The formwork tensioning holes adopt reserved tensioning grooves on the side formwork. During construction, a 5 cm PVC pipe is embedded to form a precast inverted arch tensioning duct; S2: Template Installation Before installing the template, carefully check whether its surface is clean and whether the release agent is evenly applied. The installation of the template is strictly carried out in the order of design requirements. The template connection adopts M20×50mm high-strength bolts to prepare the bottom template, side template and inner template; the bottom template is a fixed template, and the side template includes a template body and a movable bracket, wherein the template body and the movable bracket are fixedly connected by bolts, and the structural diagrams of the side template and the bottom template are shown as follows: Figure 2 and Figure 3 As shown, Figure 2 As shown, the inner formwork is the formwork surrounding the three holes on the side formwork diagram, where the side formwork is a triangular support formwork with 250a I-beams supported by tracks and 50*50mm angle irons for sliding tracks. During reinforcement, the sliding side formwork triangular support system is connected and stabilized with high-strength bolts to avoid displacement of the formwork during concrete pouring; the joints between the formworks are sealed with double-sided tape. Avoid welding near the formwork as much as possible. If welding is necessary, use a thin iron sheet to protect the top of the formwork to ensure that welding slag does not splash onto the formwork. After the formwork is installed, check and accept its geometric dimensions, top horizontality, node connections, and longitudinal and lateral stability; (3) Prototype mold splicing First, the prefabricated assembly platform is poured with concrete, and the longitudinal slide rails are embedded in the assembly platform; Use a lifting machine to lift the bottom template and place it on the assembly platform, then fix and connect the triangular fixing frames on both sides of the bottom template to the parts that contact the slide rail; After the fixation is completed, the side template is hoisted, and then the template body is fixedly connected to the two sides of the bottom template respectively, and then the movable bracket is hoisted and placed on the slide rail to connect the movable bracket and the slide rail to form a prototype frame; Then, a protective layer pad is applied under the inverted arch steel frame, the inverted arch steel frame is hoisted and moved to the top of the prototype frame and lowered, and the thickness of the protective layer pad is adjusted to 5 cm, and the assembly is completed; (4) Embedded parts construction 1) A 50mm PVC pipe with a length of 1.7m is embedded in the tensioning hole groove of the side formwork reserved in the longitudinal direction after the prefabrication is completed. When the concrete strength reaches 75% of the design strength, the PVC pipe is pulled out; 2) The reserved holes for the reinforcement of the prefabricated inverted arch are reserved with rubber rods. The rubber rods are conical, thick at the top and thin at the bottom, and gradually become thinner from top to bottom. The inner diameter of the top is 30mm and the inner diameter of the bottom is 25mm. The reinforcement holes are pre-buried in advance. When the concrete strength reaches 75% of the design strength, the rubber rods are pulled out to obtain the assembled inverted arch mold; The anchor bars are 20 steel bars, and the adhesive is modified epoxy resin or modified vinyl phenol. The performance of the adhesive should meet the relevant standards. 3) Reserve a grouting hole at the top of the prototype mold after installation. The grouting hole consists of a grouting pipe, a casing, a screw cap, and a check valve. A sealing ring is provided at each connection part between the screw cap and the grouting pipe, and between the grouting pipe and the casing. The connections between the components of the grouting hole and between the grouting pipe and the segment should be tight without slurry leakage. The appearance surface of the embedded part should be shiny, flat, with clear threads, uniform material, no bubble holes, and no peeling phenomenon. (4) Concrete construction S1: In this embodiment, all the concrete for the invert precast blocks uses C40 high-performance concrete. To ensure good workability of the concrete, strict regulations are imposed on the concrete raw materials, mix ratio, etc. Certain restrictions are placed on the maximum particle size grading, sand ratio, and minimum cement dosage of the aggregate. Concrete admixtures are added to ensure the workability of the concrete. High-efficiency retarder-water reducers are added to the concrete to improve the initial setting and final setting times of the concrete to meet the requirements of the invert concrete construction. S2: Concrete mixing and transportation The concrete is centrally batch-mixed at the 2# mixing plant and transported from the 2# mixing plant to the precast invert site of the Yaopocun Tunnel by concrete mixer trucks via the G345 National Highway. The concrete transportation time is generally controlled for transportation and pouring in the morning or evening. The initial setting time of the concrete is greater than 45 minutes, and the final setting time is less than 10 hours. During construction, a crane is used to lift the hopper to pour the concrete into the mold. The concrete mixing is carried out strictly according to the design mix ratio, and the water-cement ratio, mixing time, and slump are strictly controlled to ensure that the mixing quality of the concrete meets the requirements. S3: Concrete pouring 1) Pour the concrete into the assembled invert mold. Try to reduce the pouring temperature of the concrete as much as possible and choose a time period with lower air temperature. Sprinkle water on the surface of the assembled invert mold before pouring and detect the slump before pouring into the mold. Discard the concrete that does not meet the requirements to ensure the quality of the concrete poured into the mold. 2) During the pouring process, assign special personnel to check the stability of the formwork, steel bars, embedded parts, etc. Deal with any displacement or deformation found in a timely manner. 3) The concrete pouring is carried out continuously, and the interruption time is less than the initial setting time of the previous layer of concrete. The vibration process is assigned to specific personnel. 4) When pouring the concrete, pour the concrete in horizontal layers. 5) The prefabricated invert block concrete adopts a vibrating process with an inserted vibrator as the main vibrator and an attached vibrator as the auxiliary vibrator. The top of the concrete is vibrated with an inserted vibrator. Three attached vibrators are equipped on each side formwork, and one attached vibrator is equipped at the bottom of the elevation angle to cooperate with the vibrating construction to ensure the quality of concrete pouring. When pouring concrete, the layer thickness shall not exceed 30cm, the horizontal movement spacing shall not exceed 50cm, and the distance from the side formwork shall be 50mm~100mm; the vibration depth of the inserted vibrator rod shall generally not exceed 2 / 3~3 / 4 of the length of the vibrator rod. When pouring in layers, insert 50mm~100mm into the lower layer of concrete to ensure that the upper and lower layers of concrete are firmly combined; the corresponding positions of the attached vibrators must be staggered to ensure uniform vibration. The vibration radius of the attached vibrator acting on the formwork is 500-750mm, and the lateral impact depth is about 250mm. Before use, install the vibrator first, and then pour concrete. When the pouring height of the concrete exceeds the installation position of the vibrator, vibration can be started; 6) When vibrating concrete, follow the principle of fast insertion and slow withdrawal, and make sure that there is no more sinking on the concrete surface and no bubbles appear on the surface, and prevent honeycomb and pockmarks. Insert the concrete faster, and withdraw it slower, and vibrate while vibrating, so as to avoid leaving voids in the concrete. 7) When vibrating concrete, parallel or plum blossom type should be adopted, but no vibration, insufficient vibration or over-vibration should be allowed; after pouring concrete, vibration should be carried out immediately, and the vibration time should be appropriate, generally it can be controlled within 25s to 40s; the vibrator should not directly contact the steel bars arranged in the formwork; there should be spare vibrators on site, which can be quickly replaced in case of failure; 8) When the following conditions are met, it indicates that the concrete has been vibrated: ① The concrete surface stops sinking, or the sinking is not significant; ② No significant bubbles appear during vibration, or no bubbles appear around the vibrator; ③The concrete surface is flat and has a laitance; ④The concrete has filled the corners of the formwork; (4) Concrete maintenance The top surface of the prefabricated inverted arch is covered with geotextile, and then the rubber hose is connected to the top surface of the inverted arch through the quick connector pre-buried on the side of the pedestal. The end of the hose is connected to the swing nozzle for spraying and curing the inverted arch surface. It is advisable to spray until the covered geotextile is fully moistened. The swing nozzle sprays water to cover the entire top surface of the inverted arch. After the side form and the inner membrane are removed, the prefabricated inverted arch block is sprayed and cured with an automatic spray curing system. The water output from the nozzle is in the form of mist, so that the curing effect can achieve the best effect. In the blind area of ​​spraying, a special person is arranged to connect the quick connector next to the pedestal to the rubber hose for spray curing to ensure the quality of curing. The pedestal is stored for natural curing for no less than 14 days. At the same time, the concrete specimens cured with the prefabricated blocks are subjected to watering curing under the same conditions, so that the strength of the specimens and the strength of the prefabricated block concrete increase synchronously; After the concrete pouring is completed, timely curing shall be carried out, and appropriate curing methods shall be selected according to different construction periods to ensure the quality of the concrete and avoid cracking on the concrete surface.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A prefabrication method for assembled inverted arch precast blocks used in single-track railway tunnels, characterized in that, It includes the following steps: Manufacture a bottom formwork, side formworks, inner formwork and an inverted arch steel reinforcement cage respectively; Splice the inverted arch steel reinforcement cage with the bottom formwork, side formworks and inner formwork in sequence to form a prototype mold; Subsequently, install embedded parts in the prototype mold to form an assembled inverted arch mold; Pour concrete into the assembled inverted arch mold and vibrate and cure it to obtain the finished product.

2. The prefabrication method of the prefabricated inverted arch precast block for a single-track railway tunnel according to claim 1, characterized in that, The side formwork includes a formwork main body and a movable support, and the formwork main body and the movable support are fixedly connected by bolts.

3. The prefabrication method of the prefabricated inverted arch precast block for a single-track railway tunnel according to claim 1, characterized in that, The prefabrication process of the inverted arch steel reinforcement cage is as follows: Process the steel bars to respectively obtain a plurality of main bars, a plurality of distribution bars and a plurality of stirrups, wherein the main bars include straight bars, arc-shaped bent bars and special-shaped bent bars; Subsequently, bind the arc-shaped bent bars, straight bars, distribution bars and stirrups in sequence according to a steel bar spacing of 10-20 cm to obtain the inverted arch steel reinforcement cage.

4. The prefabrication method of the prefabricated inverted arch precast block for a single-track railway tunnel according to claim 2, characterized in that, The splicing process of the mold prototype is as follows: A concrete prefabrication and assembly platform, and longitudinal slide rails are embedded in the assembly platform; Lift the bottom formwork and place it on the assembly platform, and then fixedly connect the triangular fixing brackets on both sides of the bottom formwork with the slide rails; After the fixation is completed, lift the side formwork, fixedly connect the formwork main body with both sides of the bottom formwork respectively, and then lift the movable support and place it on the slide rails to connect the movable support with the slide rails to form a prototype frame; Subsequently, apply protective layer cushion blocks under the inverted arch steel reinforcement cage, lift the inverted arch steel reinforcement cage and move it above the prototype frame and lower it, adjust the thickness of the protective layer cushion blocks, and the assembly is completed.

5. The prefabrication method of the prefabricated inverted arch block for a single-track railway tunnel according to claim 4, characterized in that, The thickness of the protective layer cushion block is 5 cm.

6. The prefabrication method of the prefabricated inverted arch precast block for a single-track railway tunnel according to claim 1, characterized in that, The steps of installing the embedded parts are as follows: Embed a 50 mm PVC pipe in the formwork tensioning hole groove reserved longitudinally on the side formwork; Subsequently, reserve an inverted arch rebar planting hole channel in the prototype mold by using a rubber rod; Subsequently, reserve a grouting hole at the top of the prototype mold; When the concrete strength reaches 75% of the design strength, pull out the PVC pipe and the rubber rod.

7. The prefabrication method of the prefabricated invert precast block for a single-track railway tunnel according to claim 6, characterized in that, The rubber rod is conical, thick at the top and thin at the bottom, and gradually tapers from top to bottom.

8. The prefabrication method of the prefabricated inverted arch precast block for single-track railway tunnels according to claim 7, characterized in that, The inner diameter of the top of the rubber rod is 30 mm, and the inner diameter of the bottom is 25 mm.

9. The prefabrication method of the prefabricated inverted arch precast block for a single-track railway tunnel according to claim 6, characterized in that, The grouting hole includes a grouting pipe, a sleeve, a screw cap and a check valve, and a sealing ring is provided at the connection part of the screw cap and the grouting pipe and between the grouting pipe and the sleeve respectively.

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