Construction method of fabricated entrance and exit structure under inner supporting system

Abstract

A construction method of an assembly type entrance and exit structure under an inner supporting system comprises the following steps that firstly, a crane installed at the top of a foundation pit is used for hoisting a bottom block of a first ring of a main body structure connecting section into the foundation pit; secondly, bottom blocks of follow-up components are hoisted in till the length of the trolley can fall down, and a walking track and a chain of the trolley are assembled; thirdly, hoisting splicing of the side wall and the top block of the first ring is conducted; fourthly, after the first ring is spliced, hoisting splicing of a side wall and a top block on a bottom plate is conducted subsequently, and splicing of a main body structure connecting section, a civil defense section, a straight section, a corner section, a straight section and an escalator foundation pit section is completed in sequence; 5, the slope lifting sections are spliced, and different slope section heights and lengths are achieved according to modulus combination; and sixthly, the U-shaped open slope lifting section and the U-shaped open section are spliced.

Description

Construction method of prefabricated entrance and exit structure under internal support system Technical Field

[0001] This invention relates to the technical field of rail transit, and in particular to a construction method for prefabricated entrance and exit structures under an internal support system. Background Technology

[0002] As a fundamental and strategic industry of the national economy, rail transit is a crucial support for building a modern industrial system. Promoting the transformation and upgrading of the construction industry is an important measure to achieve high-quality development of rail transit. Prefabricated assembly construction technology, with its advantages of being green, environmentally friendly, and energy-saving, has become an important future development direction for rail transit construction.

[0003] Currently, the research and application of prefabrication and assembly construction technology for the main structure of subway stations has achieved initial scale and results. However, the entrance and exit sections, as ancillary structures of stations, have a low degree of standardization due to the variety of structural components, including straight sections, civil defense sections, different types of corner sections, and lifting sections. There are no application cases of using prefabrication and assembly technology for the entire entrance and exit section.

[0004] Entrance and exit structures are typically completed towards the end of the civil engineering phase, leading to frequent rush work. Cast-in-place construction presents challenges such as long construction periods, difficulty in quality control, and high risks associated with rushed work. Precast assembly technology can effectively address these issues, improving both construction efficiency and quality.

[0005] Under internal support conditions, with numerous supports, the use of prefabricated assembly technology presents a significant challenge: how to coordinate support removal with hoisting and assembly while ensuring pit stability. Furthermore, the following technical issues arise during construction: 1. Conflict between internal support and assembly procedures: The narrow construction space under the internal support system and the complex assembly sequence of supports and prefabricated components make it difficult to remove supports and hoist components while ensuring pit stability. 2. Diverse structural types leading to assembly difficulties: Entrance structures include various types such as straight sections, air-raid shelter sections, corner sections, escalator sections, ramp sections, and open sections, with significant variations in cross-sectional dimensions and a lack of a unified assembly and connection system. 3. Difficulty in balancing force transfer and pit stability: Traditional support removal methods easily lead to pit instability, lacking effective means to achieve horizontal force transfer and force conversion during assembly. 4. Low construction efficiency and difficulty in quality control: Cast-in-place construction has a long cycle and is greatly constrained by site conditions, making standardized and industrialized construction difficult, affecting overall construction quality and progress.

[0006] Therefore, the existing technology has the following disadvantages: Disadvantages of the existing technology: 1. The existing technology adopts cast-in-place construction. Since the entrance and exit are in the late stage of civil construction and need to be rushed, the cast-in-place process (formwork, reinforcement binding, pouring, curing) takes a long time, resulting in delays in the construction period; on-site operations rely on manual operation, and the concrete mix ratio and reinforcement binding accuracy are greatly affected by the environment and personnel skills, resulting in a wide range of quality fluctuations; during rushing construction, high-altitude and cross-operations are frequent, and safety protection measures are difficult to keep up with, significantly increasing the operational risks - the essence is the contradiction between the "multi-process on-site and highly dependent on manual labor" characteristics of cast-in-place construction and the need for rushing construction.

[0007] 2. Derivation of shortcomings of existing technology: Under the internal support system, the construction space is narrow due to the support obstruction. Existing technology lacks hoisting path planning and assembly coordination schemes for prefabricated components, and does not utilize the temporary force transfer device designed for the top and bottom blocks of the structure itself. As a result, the foundation pit loses stable support after the support is removed. Additional temporary supports need to be built when the supports are reversed or replaced, which is complicated and costly. In essence, the existing technology does not combine the "structural characteristics" with the "stress requirements of the foundation pit" and lacks an integrated stress conversion design.

[0008] 3. The cross-sectional dimensions and types of the various structural sections at the entrance and exit vary greatly. Existing technology lacks standardized transition and connection components, and the connection between sections relies on on-site cutting and adjustment, resulting in low precision. At the same time, the joints within and between rings only use simple bolt connections, without dedicated waterproof sealing gaskets and tensioning and locking measures, resulting in poor water tightness. The essence is that existing technology lacks "modular design thinking" and has not designed dedicated technical solutions for the connection and waterproof sealing between sections, which makes it impossible to assemble the entire section and results in insufficient structural durability.

[0009] 4. Existing assembly trolleys lack anti-slip measures for sloping sections, relying solely on their own braking during slope construction, which can easily lead to slippage due to brake failure; the U-shaped open sections lack optimized segmentation based on the cantilever height of the side walls, and the joint placement is unreasonable, making the side walls prone to deformation during assembly; the initial support layout does not take into account assembly requirements, and the support positions conflict with component hoisting and trolley movement—essentially, the existing technology lacks "full-process adaptability design," failing to develop specific plans for the construction risks of special sections and their correlation with the initial support layout, thus hindering assembly construction.

[0010] Therefore, in view of the above-mentioned defects, the designers of this invention, through dedicated research and design, and by integrating years of experience and achievements in related industries, have researched and designed a construction method for prefabricated entrance and exit structures under an internal support system to overcome the above-mentioned defects. Summary of the Invention

[0011] The purpose of this invention is to provide a construction method for prefabricated entrance and exit structures under an internal support system. This method enables the assembly and assembly of the entire entrance and exit structure with a low standardization within a narrow space under an internal support system, including straight sections, civil defense sections, corner sections, escalator sections, ramp sections, and open sections. The entire entrance and exit structure adopts a modular design, with precast concrete components prefabricated in the factory and then transported to the site for rapid assembly.

[0012] To achieve the above objectives, this invention discloses a construction method for a prefabricated entrance / exit structure under an internal support system, characterized by the following steps: Step 1: First, using a crane installed at the top of the foundation pit, the bottom block of the first ring of the main structure connection section is hoisted into the foundation pit, with the width of the single ring controlled within the distance between the two supports of the internal support; Step 2: The bottom blocks of subsequent components are hoisted in. If the main structure connection section only has the first ring, the bottom blocks of the transition ring frame of the civil defense section and the bottom blocks of the standard ring frame of the subsequent civil defense section are hoisted until the length of the trolley can be lowered. Then, the side walls and top blocks of the first ring are hoisted and assembled. If the main structure connection section has other rings, the bottom blocks of other rings, the bottom blocks of the transition ring frame of the civil defense section, and the bottom blocks of the standard ring frame of the subsequent civil defense section are hoisted in sequence until the length of the trolley can be lowered, and the traveling rails and chains of the trolley are assembled; Step 3: ... Step 4: After assembling the first ring, the side walls and top blocks of the subsequent base plate are hoisted and assembled. The trolley is moved once after assembling n rings of side walls and top blocks. Before moving, the subsequent base blocks are hoisted in, and the trolley's running track and chain are assembled on the subsequent base blocks. Then, the trolley moves along the chain through a motor reducer or motor-driven gear. The hoisting and assembly of the side walls and top blocks are repeated. In this way, the main structure connection section, civil defense section, straight section, corner section, straight section, and escalator pit section are assembled in sequence. Step 5: Assemble the ramp lifting section, and realize the different heights and lengths of the ramp sections according to the modular combination. Step 6: Assemble the U-shaped open ramp lifting section and the U-shaped open section. These two sections are directly hoisted in by a crane. After assembling the last ring of the U-shaped open section, the assembly of the entire prefabricated entrance and exit structure is completed.

[0013] The specific assembly steps in step three are as follows: Step 3.1: The trolley is lowered onto the running track and positioned; Step 3.2: The side wall components are hoisted using a gantry crane, and the verticality of the side wall panels is adjusted by the side adjustment cylinders of the trolley to assemble the side wall panels into place; Step 3.3: The top block is hoisted using a gantry crane, and the trolley lifting cylinder extends a certain distance to place the top block on the crossbeam of the trolley. The posture of the top block is adjusted by the longitudinal movement mechanism, the transverse movement mechanism, and the lifting mechanism of the trolley to assemble the top block into place.

[0014] In step four, the longitudinal precast components are connected and locked together using jacks and tensioning rods.

[0015] Among them, the cross-sectional dimensions between the transition ring frame of the civil defense section and the standard ring frame of the civil defense section need to be converted, and the length of the outriggers of the trolley needs to be adjusted to adapt to the assembly of this section.

[0016] Among them: after each single ring is formed, the trench is backfilled in time. At the position where the support needs to be removed, after removing the support below the internal support in the foundation pit, the formed structure is used to use the limiting support device at the required position to transfer the horizontal force, complete the force conversion, and ensure the stability of the foundation pit.

[0017] Step 5 involves the following steps: Step 5.1: Using a gantry crane, assemble multiple base blocks of the ramp lifting section sequentially until the ramp lifting section assembly trolley can be placed on them. Assemble the running track and chain of the ramp lifting section assembly trolley on these base blocks and load it into the trolley. Step 5.2: Assemble the side wall panels of the ramp lifting section. Use a gantry crane to lift the side wall panels in, adjust their verticality using the side adjustment cylinders of the ramp lifting section assembly trolley, and assemble the side wall panels into place. Then, use a gantry crane to lift them. The top block of the section is raised a certain distance by the lifting cylinder of the ramp lifting section assembly trolley, and placed on the crossbeam of the top block trolley. The posture of the top block is adjusted by the longitudinal movement mechanism, transverse movement mechanism and lifting mechanism of the ramp lifting section assembly, and the top block is assembled into place. The subsequent assembly is completed in sequence. Step 5.3: For each n ring side wall and top block of the ramp lifting section, the ramp lifting section assembly trolley is moved once. The side wall and top block are lifted and assembled repeatedly by the motor reducer or motor-driven gear along the chain to complete the assembly of other rings.

[0018] As can be seen from the above, the prefabricated entrance / exit structure construction method under the internal support system of the present invention has the following effects: it realizes the assembly and assembly of the entire entrance / exit structure with a low standardization structure in a narrow space under the internal support system, including the straight section, the civil defense section, the corner section, the escalator section, the ramp section, and the open section. The entire entrance / exit structure adopts a modular design, and the precast concrete components are prefabricated in the factory and then transported to the site for rapid assembly.

[0019] This patent utilizes the top and bottom blocks of the prefabricated entrance and exit structure to install limiting supports or grout-filling bag structures to achieve the replacement of the internal support system, completing the force conversion and ensuring the stability of the foundation pit during assembly.

[0020] This patent proposes a preliminary support principle applicable to the design of prefabricated entrance and exit structures, thereby improving the efficiency of assembly and construction.

[0021] A transition ring frame is used to achieve a smooth connection between different cross-sectional structural sections, ensuring the integrity of the structure and its waterproof sealing performance.

[0022] We propose assembly techniques and trolley anchoring measures applicable to special structures such as sloping sections and U-shaped trough sections to ensure construction safety and accuracy.

[0023] The details of this invention will become apparent from the following description and the accompanying drawings. Attached Figure Description

[0024] Figure 1 shows a schematic diagram of the prefabricated entrance / exit structure (arc-shaped corner segment) in this invention.

[0025] Figures 2A and 2B show the elevation and perspective views of the prefabricated entrance / exit (right-angle corner section) in this invention, respectively.

[0026] Figure 3 shows a schematic diagram of the block structure in this invention.

[0027] Figure 4 shows a schematic diagram of the bent bolt single tongue and groove tenon joint of the present invention.

[0028] Figures 5A, 5B, and 5C show the cross-sectional view, top view, and front view of the longitudinal tensioning in this invention, respectively.

[0029] Figure 6 shows a schematic diagram of the transition ring frame of the civil defense section in this invention.

[0030] Figures 7A, 7B, and 7C respectively show schematic diagrams of the transition ring frame of the right-angle corner segment in this invention.

[0031] Figure 8 shows a partial schematic diagram of the standard cross-sectional structure in the right-angle corner segment of the present invention.

[0032] Figure 9 shows a schematic diagram of the arc-shaped corner segment in this invention.

[0033] Figures 10A, 10B, and 10C show the front view, top view, and side view of one embodiment of the wedge block in this invention, respectively.

[0034] Figures 11A and 11B show the front view and schematic diagram of the transition ring frame of the escalator pit section in this invention, respectively.

[0035] Figure 12 shows a schematic diagram of the cross-section of the escalator pit section in this invention.

[0036] Figures 13A and 13B show schematic diagrams of the cross-section of the ramp lifting section in this invention.

[0037] Figures 14A, 14B, 14C and 14D show schematic diagrams of the U-shaped block in this invention.

[0038] Figures 15A to 15F show schematic diagrams illustrating the construction steps of the prefabricated entrance / exit structure construction method under the internal support system of the present invention.

[0039] Figure 16 shows a schematic diagram of the assembly under internal support conditions in this invention.

[0040] Figure 17 shows the relationship between the assembled and replaced supports of the prefabricated entrance and exit under the internal support system of the present invention.

[0041] 1-Main structure connection section; 2-Civil defense section; 3-Straight section; 4-Corner section; 5-Escalator pit section; 6-Sloping lifting section; 7-U-shaped open sloping lifting section; 8-U-shaped open section; 9-Tenon; 10-Tongue groove; 11-Bent bolt; 12-Embedded sleeve; 101, 102-Waterproof sealing gasket; 103-Longitudinal tensioning steel bar; 401-Cable-type longitudinal tensioning; 14-Removal support; 141-Original support position of lifting section; 15-Limiting support device; 16-Flat trench; 17-Retaining pile / diaphragm wall; 18-First internal support; 19-Second internal support; 20-Third internal support; 503-Trolley heightening plate Detailed Implementation

[0042] Referring to Figures 1 to 17, the construction method of the prefabricated entrance / exit structure under the internal support system of the present invention is shown.

[0043] The prefabricated entrance / exit structure is divided into longitudinal multi-ring structural rings with a fixed module (thickness). Each structural ring (i.e., structural cross-section) is further divided into blocks according to its size. As shown in Figures 1, 2A, and 2B, the prefabricated entrance / exit structure includes the following sections arranged in sequence: main structure connecting section 1, civil defense section 2, straight section 3, corner section 4, escalator pit section 5, ramp lifting section 6, U-shaped open ramp lifting section 7, and U-shaped open section 8. The corner section 4 can be a right-angle corner section (as shown in Figures 2A and 2B) or an arc-shaped corner section (as shown in Figure 1) using a wedge block structure, depending on the construction needs of different entrances / exits. The structural sections are connected to each other through transition ring frames (as shown in Figures 6, 11A, and 11B).

[0044] If no joints are used, due to transportation and hoisting limitations, the side walls can be divided into one or two structural sections, as shown in Figure 3. The side walls on both sides are independently set between the upper and lower structural sections and connected to the upper and lower structural sections at both ends, including the top section A, the bottom section C, and the two side walls BL and BR. A bent bolt single-mortise and tenon joint is used within the ring, as shown in Figure 9. This bent bolt single-mortise and tenon joint includes a tenon 9 and a mortise 10 with mutually matching shapes. A bent bolt 11 passes between the tenon 9 and the mortise 10 for locking during construction before backfilling. Depending on the actual use, this bent bolt may not be necessary. The bent bolt 11 passes through a pre-embedded sleeve 12. Waterproof sealing gaskets can be installed at the joints on both sides of the tenon 9 and the mortise 10, and single or double waterproof sealing can be used depending on actual needs. The gasket used in the figure is a double waterproof sealing gasket, which has an outer first waterproof sealing gasket 101 and an inner second waterproof sealing gasket 102. If a single waterproof sealing gasket is used, the other side of the joint is filled with a grout stopper. Epoxy resin or cement-based grout can be injected between the first waterproof sealing gasket 101 and the second waterproof sealing gasket 102 to fill and limit the tenon and mortise. The tenon 9 is set upwards, so if the bottom is first installed with a groove before it is assembled into a ring, it is easy to accumulate dust and difficult to clean.

[0045] The joints between the rings also adopt a single tongue and groove joint, or the longitudinal tensioning method of longitudinal tensioning steel bar 103 ring by ring can be adopted, as shown in Figures 5A, 5B and 5C. The tensioning points of the front and rear ring blocks are set with separate tensioning anchor points. The joints between the rings and the joints inside the rings are also equipped with waterproof sealing gaskets (which may also include the first waterproof sealing gasket 101 and the second waterproof sealing gasket 102). The waterproof sealing gaskets are tightened by tensioning and locking to achieve the sealing and waterproofing of the prefabricated entrance and exit structure.

[0046] Among them, the civil defense section 2 is connected to the main structure connecting section 1 and the straight section 3 through the transition ring frame shown in Figure 6. The transition ring frames of the civil defense sections at both ends of the civil defense section 2 are connected to the standard ring frame of the civil defense section. The straight section 3 is connected to the corner section 4 after being transformed by the transition ring frame of the corner section. The corner section 4 can be either an arc corner section or a right-angle corner section according to the construction requirements.

[0047] The right-angle corner segment includes right-angle transition ring frames connecting the two ends and multiple corner expansion segments in the middle. The right-angle transition ring frames connect the straight segments at both ends, as shown in Figures 7A, 7B, and 7C. The right-angle transition ring frame can be a single piece of structure, thereby ensuring structural stability and integrity. Its top is connected to the standard cross-section of the right-angle corner segment through a tongue-and-groove joint. The right-angle transition ring frame is reliably connected to the standard cross-section of the right-angle corner segment perpendicular to 90 degrees through tongue-and-groove joints. Longitudinal tensioning is also achieved through the transition ring frame to realize the conversion of longitudinal tensioning in two vertical directions.

[0048] The entire arc-shaped corner segment is shown in Figure 9. Its cross-section adopts a wedge-shaped block structure in the longitudinal direction, which includes multiple sequentially connected wedge-shaped blocks to form an arc-shaped bending structure. The angles are adjusted by the thickness difference between the bottom and top of the wedge-shaped blocks. The cross-section can be divided into sections or a whole according to the actual construction conditions, as shown in Figures 10A, 10B, and 10C. The wedge-shaped blocks adopt an upper and lower segmented structure, i.e., including a top block and a bottom block. The multiple wedge-shaped blocks (i.e., longitudinal rings) of the arc-shaped corner segment are longitudinally tensioned using a cable-type longitudinal tensioning method. The arc-shaped corner segment does not require a reversal of the longitudinal tensioning direction; it can be directly tensioned by connecting the arc-shaped bend.

[0049] The corner section is connected to the straight section 3, and then connected to the escalator pit section 5 through the transition ring frame of the escalator pit section to ensure longitudinal continuity and tension locking, as shown in Figures 11A and 11B. The bottom block height of the lower part (dark shaded part) of the transition ring frame of the escalator pit section is determined according to the cross-sectional height of the next escalator pit section 5. The cross-section of the standard section of the escalator pit section is shown in Figure 12. Its block joints are set on the side wall. The block division principle, joint connection method and whether it is block-based are consistent with the form of the aforementioned straight section and other sections.

[0050] The escalator pit section 5 is followed by the ramp lifting section 6. The cross-sectional shape of the ramp lifting section 6 is shown in Figures 13A and 13B. Its cross-section can be adjusted by changing the modular thickness to achieve different angles and heights for the lifting section assembly. That is, if the overall ring width is 'a', the ring width of the lifting section can be set to 'b', 'c', etc. By combining 'a' with 'b', 'c', etc., the height and length can be adjusted. The ramp angle of the lifting section determines the slope of each standard ring of the lifting section. The sidewall segmentation principle, joint connection method, and whether or not to segment are consistent with the aforementioned straight sections and other sections.

[0051] The ramp lifting section 6 is followed by the U-shaped open ramp lifting section 7. The structure of each U-shaped block in the U-shaped open ramp lifting section 7 is shown in Figures 14A, 14B, 14C, and 14D. Since the ramp needs to be lifted, the height of the side wall of each U-shaped section is set sequentially according to the required angle, thus forming the ramp. At least one U-shaped block has a three-section bottom block, and the tenon joint is set at one-third of the bottom block. The U-shaped open ramp lifting section 7 is followed by the U-shaped open section 8. The side wall of the U-shaped open section 8 is relatively short and is not divided into blocks, but uses a whole block structure.

[0052] The specific steps of the construction method of the prefabricated entrance and exit structure under the internal support system of the present invention are as follows: Step 1: First, the bottom block of the first ring of the main structure connecting section 1 is hoisted into the foundation pit using a crane installed at the top of the foundation pit. The width of the single ring is controlled within the distance between the two supports of the internal support. For example, if the support distance is 4m, the width of the single ring is less than 4m when hoisting in. The first ring is connected using the sleeve bolts pre-embedded in the main structure section of the station.

[0053] Step 2: Hoist the bottom blocks of subsequent components. If the main structure connection section 1 only has the first ring (i.e., the main structure connection section 1 is a single-ring structure), hoist the bottom block of the transition ring frame of the civil defense section 2 and the bottom block of the standard ring frame of the subsequent civil defense section until the length of the trolley can be lowered (as shown in Figure 15A). Then, hoist and assemble the side walls and top blocks of the first ring. If the main structure connection section 1 has other rings, hoist the bottom blocks of the other rings, the bottom blocks of the transition ring frame of the civil defense section, and the bottom blocks of the standard ring frame of the subsequent civil defense section in sequence until the length of the trolley can be lowered. Then assemble the traveling rails and chains of the trolley.

[0054] Step 3: Hoist and assemble the side walls and top block of the first ring. Specific assembly steps: Step 3.1: Lower the trolley onto the traveling track and position it; Step 3.2: Use a gantry crane to hoist the side wall components, adjust the verticality of the side wall panels using the side adjustment cylinders of the trolley, and assemble the side wall panels into place; Step 3.3: Use a gantry crane to hoist the top block, extend the trolley's lifting cylinder a certain distance, place the top block on the trolley's crossbeam, and adjust the posture of the top block using the trolley's longitudinal movement mechanism, transverse movement mechanism, and lifting mechanism to assemble the top block into place.

[0055] Step 4: After assembling the first ring, proceed with the hoisting and assembly of the side walls and top blocks on the subsequent base plate. The trolley is moved once after assembling every n rings of side walls and top blocks (depending on the trolley length and ring width; n times the ring frame length must be greater than the trolley length). Before moving, the subsequent base blocks are hoisted in, and the trolley's running track and chain are assembled on the subsequent base blocks. Then, the trolley moves along the chain via a motor reducer or motor-driven gears. This process of hoisting and assembling the side walls and top blocks is repeated, thus completing the assembly of the main structure connection section 1, civil defense section 2, straight section 3, corner section 4, straight section 3, and escalator pit section 5 in sequence (as shown in Figures 15B, 15C, and 15D).

[0056] In this process, the longitudinal precast components are connected and locked together using jacks and tensioning rods. If the cross-sectional dimensions of the front and rear sections are inconsistent during longitudinal tensioning, a transition ring frame is used for conversion. At the location of the structural ring frame, the tensioning points of the front and rear rings need to be set separately for tensioning anchor points.

[0057] Among them, the cross-sectional dimensions between the transition ring frame and the standard ring frame of the civil defense section need to be converted, and the rings are tensioned to connect them. After the transition ring frame of the civil defense section is installed, the standard ring frame of the civil defense section is installed until there is a fire door. The transition ring frame of the civil defense section can also be installed at the fire door. Through the conversion of the transition ring frame of the civil defense section, the next section can be connected to the standard section of the civil defense section until the straight section 3 needs to be connected. Since the cross-sectional dimensions of the transition ring frame of the civil defense section and the standard ring frame of the civil defense section are different from those of the straight section 3, the trolley needs to adjust the length of the outriggers to adapt to the assembly of this section, as shown in Figure 15, which shows the main structure connecting section 1 and civil defense section 2.

[0058] After each ring is formed, the trough 16 in Figure 17 is backfilled promptly. At the location where the support needs to be removed, after removing the support below the internal support 18 in the foundation pit, the formed structure is used to transfer the horizontal force at the required location using a limiting support device 15, completing the force conversion and ensuring the stability of the foundation pit. The limiting support device can be a slurry-filled bag or a steel support.

[0059] When the corner segment is a right-angle corner segment, a corner segment transition ring frame is used to connect the straight segment 3 and the corner enlargement segment, as shown in Figure 7. This corner segment transition ring frame plays a role in ensuring structural stability and integrity. The top is connected to the standard cross-section of the right-angle corner segment through a tongue and groove tenon. This standard cross-section is shown in Figure 8. After installing the right-angle corner segment transition ring frame, the standard cross-section component of the right-angle segment is then installed.

[0060] When the corner segment is an arc-shaped corner segment, a cable-type longitudinal tensioning method (401) is used to splice the wedge-shaped section ring by ring, as shown in Figures 9 and 10A, 10B and 10C. If each section is divided into blocks, they are arranged in order from bottom to top. After this segment is completed, a transition ring frame is used to complete the transition and connection with the next straight segment 3 (right-angle corner segment). The arc-shaped corner segment does not require a transition ring frame because its dimensions are the same as those of the straight segment 3, and it can be directly connected, as shown in the assembly sequence in Figure 15.

[0061] The straight section 3 is connected to the escalator pit section 5 via a transition ring frame to ensure longitudinal continuity and tension locking. The transition ring frame is shown in Figure 11, and its lower height is determined based on the height of the next section. The standard section cross-section of the escalator pit section 5 is shown in Figure 12.

[0062] After the trolley rotates, adjust the trolley outriggers and perform splicing in another direction. Connect the straight section 3, and use the transition ring frame of the escalator pit section cross-section to splice the escalator pit section 5.

[0063] Among them, the bottom height of the escalator pit section 5 is greater than the front section, so a trolley heightening plate 503 needs to be added, and then the trolley is used for assembly, as shown in the assembly sequence of the escalator pit section 5 in Figure 15.

[0064] The trolley can be adjusted using its side and top outriggers to assemble components of different sizes.

[0065] Step 5: Assemble the ramp lifting section 6, and combine different ramp sections according to modular combinations to achieve different heights and lengths. Specifically, the following steps can be taken: Step 5.1: As shown in Figures 15E and 15F, use a gantry crane to assemble multiple bottom blocks of the ramp lifting section 6 in sequence until the ramp lifting section assembly trolley can be placed. Assemble the running track and chain of the ramp lifting section assembly trolley on these multiple bottom blocks, and load it into the ramp lifting section assembly trolley. In order to prevent the ramp lifting section assembly trolley from slipping and falling due to the failure of the gear chain braking mechanism, necessary anchoring measures are taken on the ramp lifting section assembly trolley on the bottom block of the ramp lifting section: Measure 1 is to add a stop block to prevent the running mechanism from rolling down the track; Measure 2 is to add an anchoring mechanism, which is anchored to the bottom trolley by a chain hoist and steel wire rope. In order not to affect the normal operation of the bottom trolley, the anchoring steel wire rope can be kept in a slack state.

[0066] Step 5.2: Assemble the side wall panels of the ramp lifting section. Use a gantry crane to hoist the side wall panels in, and adjust the verticality of the side wall panels using the side adjustment cylinders of the ramp lifting section assembly trolley. Once the side wall panels are in place, use the gantry crane to hoist the top block of the lifting section. Extend the lifting cylinder of the ramp lifting section assembly trolley a certain distance and place the top block on the crossbeam of the top block trolley. Adjust the posture of the top block using the longitudinal movement mechanism, transverse movement mechanism, and lifting mechanism of the ramp lifting section assembly to assemble the top block into place. Repeat this process to complete the subsequent assembly steps.

[0067] Step 5.3: Move the ramp lifting section assembly trolley once for each n-ring sidewall and top block of the assembled ramp lifting section (depending on the length of the ramp lifting section assembly trolley and the ring width; n times the ring width must be greater than the length of the ramp lifting section assembly trolley). Before moving, hoist the bottom block of the following ramp lifting section, and assemble the running track and chain of the ramp lifting section assembly trolley on the bottom block of the following ramp lifting section. Then, move along the chain through the motor reducer or motor-driven gear, repeating the hoisting and splicing of the sidewalls and top blocks to complete the assembly of the other rings.

[0068] Step Six: Assemble the U-shaped open ramp lifting section 7 and the U-shaped open section 8. These two sections are directly lifted in by a crane. After assembling the last link, the U-shaped open section 8, the assembly of the entire prefabricated entrance and exit structure is completed.

[0069] During the assembly of the corner section, the trolley turns and components are lowered. After the bottom block is assembled, the bottom support (third inner support 20) is removed, backfilling is carried out promptly, and the limiting support device 15 is installed, as shown in Figure 17. This horizontal force transmission converts the support force into a horizontal force transmission system formed by the support device and structure, ensuring the stability of the foundation pit. After removing the second inner support 19, the limiting support device 19 is installed using the top components to achieve the force conversion of the second support.

[0070] The bottom block of the ramp lifting section is assembled, the supports within the ramp section are dismantled, and the ramp section components are assembled. The support arrangement within the ramp section is shown at dismantling position 14 in Figure 16. The original support position 141 of the lifting section needs to be adjusted to the oblique arrangement shown at dismantling position 14 during the prefabricated entrance and exit structure assembly project before the foundation pit is excavated.

[0071] Therefore, this invention achieves efficient, safe, and high-quality construction of prefabricated entrance / exit structures under internal support conditions through innovative methods such as modular design, transition ring frame connection, limit support force conversion, and standardized assembly process. Specific advantages include: significantly improved construction efficiency: the use of prefabricated components and a dedicated assembly trolley enables rapid hoisting and precise assembly, greatly shortening the construction period and reducing on-site wet work; strong foundation pit stability: the limit support device achieves horizontal force transmission, ensuring foundation pit stability during support removal and avoiding the risks associated with traditional support replacement; strong structural adaptability: the transition ring frame and variable modular design adapt to different cross-sectional dimensions and structural types, achieving standardized assembly of the entire entrance / exit section; high quality controllability: the factory-prefabricated components have stable quality, the on-site assembly process is standardized, the joint waterproofing performance is reliable, and the overall structure has good durability; superior safety performance: specific construction measures are proposed for complex working conditions such as slope sections and corner sections to ensure construction safety during hoisting, assembly, and trolley operation.

[0072] It is obvious that the above description and account are merely illustrative and not intended to limit the disclosure, application, or use of this invention. Although embodiments have been described and illustrated in the accompanying drawings, the invention is not limited to the specific examples exemplified by the drawings and described in the embodiments as currently considered the best mode for carrying out the teachings of the invention. The scope of the invention will include any embodiments falling within the foregoing description and the appended claims.

Claims

1. A construction method for a prefabricated entrance / exit structure under an internal support system, characterized in that... The process includes the following steps: Step 1: First, using a crane installed at the top of the pit, the bottom block of the first ring of the main structure connection section is hoisted into the pit, with the width of each ring controlled within the distance between the two inner supports; Step 2: The bottom blocks of subsequent components are hoisted in. If the main structure connection section only has the first ring, the bottom blocks of the transition ring frame of the civil defense section and the bottom blocks of the standard ring frame of the subsequent civil defense section are hoisted until the length of the trolley can be lowered. Then, the side walls and top blocks of the first ring are hoisted and assembled. If the main structure connection section has other rings, the bottom blocks of other rings, the bottom blocks of the transition ring frame of the civil defense section, and the bottom blocks of the standard ring frame of the subsequent civil defense section are hoisted in sequence until the length of the trolley can be lowered, and the trolley's running track and chain are assembled; Step 3: The side walls and top blocks of the first ring are hoisted and assembled; Step 4: Complete. After assembling the first ring, the subsequent side walls and top blocks on the base plate are hoisted and assembled. The trolley is moved once after assembling every n rings of side walls and top blocks. Before moving, the subsequent base blocks are hoisted in, and the trolley's running track and chain are assembled on the subsequent base blocks. Then, the trolley moves along the chain via a motor reducer or motor-driven gears, repeating the hoisting and assembly of the side walls and top blocks. This process sequentially completes the assembly of the main structure connection section, the civil defense section, the straight section, the corner section, the straight section, and the escalator pit section. Step five: Assemble the ramp lifting section, using modular combinations to achieve different ramp heights and lengths. Step six: Assemble the U-shaped open ramp lifting section and the U-shaped open section. These two sections are directly hoisted in by a crane. After assembling the last ring of the U-shaped open section, the entire prefabricated entrance / exit structure is assembled.

2. The construction method for prefabricated entrance / exit structure under an internal support system as described in claim 1, characterized in that: The specific assembly steps in step three are as follows: Step 3.1: Lower the trolley onto the running track and position it; Step 3.2: Use a gantry crane to lift the side wall components, adjust the verticality of the side wall panels using the side adjustment cylinders of the trolley, and assemble the side wall panels into place; Step 3.3: Use a gantry crane to lift the top block, extend the trolley's lifting cylinder a certain distance, place the top block on the trolley's crossbeam, and adjust the posture of the top block using the trolley's longitudinal movement mechanism, transverse movement mechanism, and lifting mechanism to assemble the top block into place.

3. The construction method for prefabricated entrance / exit structure under an internal support system as described in claim 1, characterized in that: In step four: the longitudinal precast components are connected and locked together by using jacks to tension the force rods.

4. The construction method for prefabricated entrance / exit structure under an internal support system as described in claim 1, characterized in that: The cross-sectional dimensions between the transition ring frame of the civil defense section and the standard ring frame of the civil defense section need to be converted, and the trolley needs to adjust the length of the outriggers to adapt to the assembly of this section.

5. The construction method for prefabricated entrance / exit structure under an internal support system as described in claim 1, characterized in that: After each ring is formed, the trench is backfilled in a timely manner. At the location where the support needs to be removed, after removing the support below the internal support in the foundation pit, the formed structure is used to transfer the horizontal force at the required location using a limiting support device, thereby completing the force conversion and ensuring the stability of the foundation pit.

6. The construction method for prefabricated entrance / exit structure under an internal support system as described in claim 1, characterized in that: Step 5 involves the following steps: Step 5.1: Using a gantry crane, assemble multiple base blocks of the ramp lifting section sequentially until the ramp lifting section assembly trolley can be placed on them. Assemble the running track and chain of the ramp lifting section assembly trolley on these base blocks and load it into the trolley. Step 5.2: Assemble the side wall panels of the ramp lifting section. Use a gantry crane to lift the side wall panels in, and adjust their verticality using the side adjustment cylinders of the ramp lifting section assembly trolley. Once the side wall panels are in place, use the gantry crane to lift the entire section. The top block is lifted by the hydraulic cylinder of the ramp lifting section assembly trolley, which extends a certain distance and places the top block on the crossbeam of the top block trolley. The posture of the top block is adjusted by the longitudinal movement mechanism, transverse movement mechanism and lifting mechanism of the ramp lifting section assembly to assemble the top block into place. The subsequent assembly is completed in sequence. Step 5.3: For each n ring side wall and top block of the ramp lifting section assembly, the ramp lifting section assembly trolley is moved once. The side wall and top block are lifted and assembled repeatedly by the motor reducer or motor-driven gear along the chain to complete the assembly of other rings.

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