Multi-section large-span tunnel secondary lining trolley and modification method

Abstract

The invention provides a multi-section large-span tunnel secondary lining trolley and a modification method, and belongs to the technical field of tunnel construction. The secondary lining trolley comprises a portal frame assembly, a formwork system and a walking system; the portal frame assembly comprises a first portal frame and a second portal frame, the tops of the two portal frames are connected with a first cross beam and a second cross beam, a group of first longitudinal beams are uniformly distributed between the two cross beams, and the second portal frame is provided with a second longitudinal beam and a shear frame; the formwork system comprises a top formwork, a side formwork and a bottom formwork, the top formwork is supported on the second cross beam through stand columns, and the side formwork is hinged to the first door frame and the second door frame through a set of movable supporting rods; the walking system comprises a first supporting leg, a second supporting leg and a steel rail laid on the inverted arch. The modular design is adopted, the core is that the portal frame assembly, the formwork system and the walking system form a reconfigurable basic platform, and the overall outline of the trolley can be changed by adjusting the number of portal frames, the connecting mode and the size of formworks so as to adapt to different tunnel sections.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a multi-section, large-span tunnel secondary lining trolley and its modification method. Background Technology

[0002] With the continuous advancement of transportation infrastructure construction in my country, tunnel engineering is being used more and more widely in highways, railways, and other transportation lines. Especially in complex terrain conditions such as mountains and hills, tunnels have become a key structure for ensuring smooth traffic flow. Long-span tunnels, due to their ability to adapt to the traffic demands of special sections, are seeing a continuous increase in their construction scale and number. Different regions, due to varying geological conditions, terrain limitations, and design requirements, have diverse needs for tunnel cross-sectional shapes and dimensions, resulting in significant differences in span range. Against this backdrop, tunnel construction equipment needs to possess greater adaptability and flexibility.

[0003] Secondary lining formwork trolleys are indispensable non-standard tooling equipment in mining tunnel construction, crucial for achieving mechanized lining construction. Traditional secondary lining trolleys are often specially designed and manufactured for specific cross-sectional dimensions and shapes. Once the tunnel cross-section changes, the existing trolleys are often unusable, requiring redesign and manufacturing of new trolleys. This process is not only time-consuming and costly but also severely impacts construction progress. Especially in multi-section, large-span tunnel construction, if traditional single-section trolleys are used, frequent disassembly, reassembly, and adjustment are necessary during transitions between different sections, resulting in cumbersome operations, long cycles, and significantly reduced construction efficiency. Furthermore, repeated disassembly and reassembly can easily damage equipment components, increasing maintenance costs and the risk of malfunctions, further affecting construction continuity and overall efficiency.

[0004] Therefore, in order to address the shortcomings of traditional secondary lining trolleys in terms of cross-sectional adaptability, construction efficiency, and economy, it is urgent to develop a secondary lining trolley system that can be quickly modified, reused, and adapted to multi-section construction, along with its supporting modification methods, to meet the pressing needs of modern tunnel engineering for efficient, versatile, and flexible construction equipment. Summary of the Invention

[0005] Purpose of the Invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a multi-section, large-span tunnel lining trolley. The multi-section includes a standard three-lane section, an emergency stopping lane, and a large span. The lining trolley comprises a gantry assembly, a formwork system, and a traveling system. The gantry assembly includes a first gantry and a second gantry, with a first crossbeam and a second crossbeam connected to the top of the first and second gantry. A set of first longitudinal beams is evenly distributed between the first and second crossbeams. The second gantry is provided with a second longitudinal beam and a shear frame from top to bottom. The formwork system includes a top formwork, side formwork, and a bottom formwork. The top formwork is supported on the second crossbeam by columns, and the side formwork is hinged to the first and second gantry by a set of movable struts. The traveling system includes a first leg, a second leg, and a steel rail laid on the invert arch. The lower ends of the first and second legs are symmetrically arranged on both sides of the steel rail.

[0006] This invention adopts a modular design. Its core lies in the fact that the gantry assembly, template system and travel system constitute a reconfigurable basic platform. By adjusting the number of gantry, the connection method and the size of the template, the overall outline of the trolley can be changed, thereby adapting to different tunnel cross sections.

[0007] Furthermore, the second crossbeam is slidably connected to the first crossbeam via the first longitudinal beam, and a translation cylinder is provided between the first crossbeam and the structure below it and the first longitudinal beam and the structure above it. The translation cylinder can perform lateral sliding fine adjustment.

[0008] The hydraulic system controls the extension and retraction of the translation cylinders, driving the first longitudinal beam and above (including the second cross beam, columns, and top formwork) to slide laterally within a small range relative to the lower gantry structure. This achieves precise alignment of the trolley formwork. Before construction, the lateral position of the top formwork can be fine-tuned to ensure precise alignment with the tunnel design centerline, guaranteeing the accuracy of lining pouring and improving construction quality. Simultaneously, this function can also compensate for minor errors in tunnel surveying or track laying.

[0009] Furthermore, a lifting cylinder is installed on the second leg, and a travel motor and rollers are installed at the bottom of the second leg. The lifting cylinder is used to raise or lower the gantry, enabling coarse adjustment of the trolley height and demolding / former erection. The travel motor drives the rollers to roll on the steel rails, providing power for the trolley's movement within the tunnel. This achieves mechanization and automation of trolley operation. The lifting cylinder makes the formwork erection and demolding processes more efficient and labor-saving; the built-in travel motor allows the trolley to move independently without relying on external traction equipment, improving construction efficiency and automation levels.

[0010] Furthermore, when the span of the multi-section structure is ≥20 meters, a third longitudinal beam is installed on the second gantry. As the span increases, the area of ​​the top formwork and the concrete pressure it bears also increase, leading to an increase in the load transferred to the second crossbeam. Adding a third longitudinal beam is equivalent to adding an extra longitudinal connection between the gantry frames, more effectively distributing the load among multiple gantry frames and enhancing longitudinal stability. This effectively improves the rigidity and stability of the overall trolley structure under large-span conditions, preventing crossbeam deformation or gantry instability due to excessive load, and ensuring construction safety and the flatness of the lining surface.

[0011] Furthermore, the first gantry is a steel structure with ventilation duct openings; the second gantry is a structure without ventilation duct openings. During tunnel construction, ventilation ducts need to pass through the gantry. Designing the gantry at specific locations with openings provides a passage for the ventilation ducts without affecting the integrity and structural strength of other gantry structures.

[0012] A method for modifying a secondary lining trolley for a multi-section, large-span tunnel as described above includes the following steps:

[0013] S1. Identify the target type of the current tunnel section;

[0014] S2. Based on the span and height parameters of the target section, determine the corresponding trolley assembly method. The assembly methods include conventional gantry type, single-assembly combination type, double-assembly combination type, single-wing outward expansion type and double-wing outward expansion type. The conventional gantry type includes at least six pairs of gantry assemblies, which are arranged at equal intervals along the longitudinal direction of the tunnel. Each pair of adjacent gantry assemblies is connected by a set of second longitudinal beams, third longitudinal beams and shear frames.

[0015] S3. Retain the basic components in the current trolley that are suitable for the target section; replace, add or remove some of the gantry, crossbeams, longitudinal beams, shear frames, columns or formwork components, and adjust the connection relationship between the components;

[0016] S4. Debug and verify the overall size, stability and function of the modified trolley to complete the modification.

[0017] Furthermore, when the assembly method adopts a single-assembly combination, it specifically includes: a conventional gantry, with a wing extending outward from the side of the conventional gantry through a first extension member. The first extension member includes a third gantry, the top of the third gantry being connected to the first and second crossbeams respectively through a first crossbeam extension section and a second crossbeam extension section. A third crossbeam is provided above the second crossbeam, and one side of the third crossbeam is widened by a third crossbeam extension section. The third crossbeam 26 and the third crossbeam extension section are connected to the top formwork through columns.

[0018] While keeping the main gantry structure unchanged, the working range of the trolley is widened to one side by adding extension components (such as extension beams or additional gantry) on one side to meet the need for widening of the tunnel cross section on one side.

[0019] Furthermore, when the assembly method adopts a double-assembly combination, it specifically includes: separating a set of six pairs of portal frames into two sets of three pairs of portal frames; adding a third crossbeam and a second shear frame; adding widened sections of the first, second, and third crossbeams respectively to the first, second, and third crossbeams; adding or extending some columns; and replacing the bottom formwork with dimensions suitable for the cross-sectional profile of the large span.

[0020] This is the core method for achieving ultra-large spans. By longitudinally splitting the long trolley and then laterally splicing the two units together, and using strong central connectors (widened sections, shear frames), a huge, unsupported arch structure is formed. This successfully solves the technical problem that traditional trolleys cannot achieve ultra-large spans (such as over 26m). This "converting length into width" approach makes full use of existing materials and new components, achieving a fundamental transformation in structural form to meet extreme cross-sectional requirements.

[0021] Furthermore, when the assembly method adopts a double-wing outward expansion type, it specifically includes: a conventional gantry frame, with extension beams and gantry legs added to both sides of the conventional gantry frame; and replacing the top formwork with dimensions suitable for the cross-sectional profile of the large span.

[0022] Based on the standard gantry sequence, by symmetrically adding extension mechanisms (extension beams and outer legs) to both sides, the templates on both sides can move outward simultaneously, thereby symmetrically increasing the trolley width. While maintaining the integrity of the core gantry structure, the trolley span is increased efficiently and symmetrically. The structure is stable, with reasonable stress distribution, and is suitable for large-span sections requiring symmetrical widening on both sides.

[0023] Furthermore, when the assembly method adopts a single-wing outward expansion type, the specific steps include: removing the third crossbeam of the double-wing outward expansion gantry, removing the extension crossbeam and gantry legs on one side, replacing the other side with a suitable extension crossbeam, replacing some columns, and replacing the two templates near the middle position on the top formwork. A simplification is made based on the double-wing outward expansion type by removing the extension structure on one side and adjusting the other side and the top formwork to reduce the trolley span and adapt to a different cross-section.

[0024] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0025] 1. Improved equipment versatility, enabling "one vehicle for multiple uses," greatly enhancing the equipment's versatility and flexibility. It eliminates the need to manufacture a new trolley for each section, significantly reducing equipment procurement, warehousing, and transportation costs, and avoiding project delays caused by trolley replacements.

[0026] 2. Significantly improved construction quality, efficiency, and safety. The overall support has good strength and rigidity, a simple structure, is easy to construct and operate, is safe and reliable, effectively shortens the construction period, and accelerates the construction progress.

[0027] 3. It conforms to the concept of green construction. The demolition and modification materials can be reused repeatedly, which greatly reduces equipment costs. It is energy-saving, environmentally friendly, economical and reasonable, and has high promotion value.

[0028] 4. Enhanced construction adaptability. The installation, dismantling, and use of the trolley do not affect the normal construction of other processes in the tunnel excavation, and can ensure the passage needs of high-volume vehicles such as dump trucks, concrete mixer trucks, and loaders. Attached Figure Description

[0029] Figure 1 A simplified structural diagram of a three-lane standard section trolley;

[0030] Figure 2 This is a schematic diagram of the gantry assembly structure for a standard three-lane section.

[0031] Figure 3 This is a schematic diagram of the three-lane trolley structure for a standard section;

[0032] Figure 4 A schematic diagram of the structure of a large-span (one) trolley;

[0033] Figure 5 A schematic diagram of the large-span (two-stage) trolley structure;

[0034] Figure 6 A schematic diagram of a large-span (three-stage) trolley structure;

[0035] Figure 7 Schematic diagram of the structure of the large-span (fourth and fifth span) emergency stop lane trolley;

[0036] Figure 8 A schematic diagram of the large-span (six) trolley structure;

[0037] Figure 9 A schematic diagram of the large-span (seven) trolley structure;

[0038] Figure 10 A schematic diagram of a large-span (eight-piece) trolley structure;

[0039] In the diagram: 1-First gantry, 2-Second gantry, 3-First crossbeam, 4-Second crossbeam, 5-First longitudinal beam, 6-Second longitudinal beam, 7-Third longitudinal beam, 8-Shear frame, 9-Column, 10-First leg, 11-Second leg, 12-Top formwork, 13-Side formwork, 14-Bottom formwork, 15-Modible support rod, 16-Steel rail, 17-Third crossbeam, 18-Second shear frame, 19-Wide section of the first crossbeam, 20-Wide section of the second crossbeam, 21-Wide section of the third crossbeam, 22-Extended section of the first crossbeam, 23-Extended section of the second crossbeam, 24-Extended section of the third crossbeam, 25-Third gantry, 26-Third crossbeam. Detailed Implementation

[0040] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments described.

[0041] Example 1

[0042] A multi-section, large-span tunnel lining trolley and its modification method are disclosed. The main line section types include a standard three-lane section, an emergency stopping lane, and large spans (I), (II), (III), (IV), (V), (VI), (VII), and (VIII). The assembly methods include five types: conventional gantry type, single-assembly combination type, double-assembly combination type, single-wing outward expansion type, and double-wing outward expansion type.

[0043] like Figures 1-3 As shown, the standard section trolley structure includes: a conventional gantry-type assembly, comprising a gantry assembly, a formwork system, and steel rails. The gantry assembly includes a first gantry 1, a second gantry 2, a first crossbeam 3, a second crossbeam 4, a first longitudinal beam 5, a second longitudinal beam 6, a third longitudinal beam 7, a first shear frame 8, columns 9, first legs 10, and second legs 11. The first gantry 1 is a steel structure with ventilation duct holes, while the second gantry 2 does not. A first crossbeam 3 is fixedly connected to the top of the first gantry 1 and the second gantry 2. Several first longitudinal beams 5 are slidably connected to the top of the first crossbeam 3. A second crossbeam 4 is installed on the top of the first longitudinal beams 5. Several columns 9 are installed above the second crossbeams 4, with the other end of each column 9 connected to the top formwork 12 for support and lifting. Several first legs 10 are installed at the bottom of the first gantry 1 and the second gantry 2. Second legs 11 are installed on both sides of the front and rear gantry frames, and lifting cylinders are installed on the second legs 11 to adjust the overall height of the gantry. The lower end of the second leg 11 is equipped with a travel motor and rollers. Along the tunnel's forward direction, the gantry frames are connected by the first longitudinal beam 5, the second longitudinal beam 6, the third longitudinal beam 7, and the first shear frame 8 to ensure the overall stability of the platform. In addition, the overall structure of the first crossbeam 3 and below can be finely adjusted laterally within 10cm by means of a translation cylinder.

[0044] The formwork system includes a top formwork 12, side formwork 13, bottom formwork 14, and movable support rods 15. The top formwork 12 is composed of several steel formwork panels, and the left and right side formwork panels 13 are each a single piece of steel formwork panel, as are the bottom formwork 14. The top formwork 12, side formwork 13, and bottom formwork 14 are all equipped with back ribs. One end of the movable support rod 15 is hinged to the first portal frame 1 or the second portal frame 2, and the other end is hinged to the back rib of the formwork panel.

[0045] After precise measurement, several support blocks are placed at designated positions on the invert arch, and steel rails 16 are installed on the support blocks. The lower ends of the first leg 10 and the second leg 11 are both placed on the steel rails 16 to support the fixed trolley or for movement.

[0046] Different types of trolleys are required for different span sections, but the overall structure is similar to that of the standard section trolley. Assembly methods include five types: conventional gantry type, single-assembly combination type, double-assembly combination type, single-wing outward expansion type, and double-wing outward expansion type. Trolleys with a span ≥20m require an additional third crossbeam to prevent structural instability caused by excessively high columns. In the attached diagram, dark-colored components represent parts that need to be replaced or added after modification. The assembly methods and parameters of the trolleys required for different span sections are shown in the table below:

[0047] Table of trolley parameters for different cross-section types

[0048]

[0049] like Figure 4 and Figure 5 As shown, the assembly method of the large-span (I) and large-span (II) trolleys is a double-assembly combination, which can be modified from one set of six pairs of masts in the standard section into two sets of three pairs of masts. Since the spans of the large-span (I) and large-span (II) trolleys are 28m and 26m respectively, a third crossbeam 17 needs to be added. The two sets of masts of the large-span (I) trolley are connected by a second shear frame 18. The first crossbeam, the second crossbeam, and the third crossbeam are respectively equipped with a widened section 19, a widened section 20, and a widened section 21 for the first crossbeam, to facilitate subsequent modification. Based on the existing columns, several columns are added or extended to ensure the stability of the trolley structure. The bottom formwork 14 is replaced with a size type suitable for the building boundary and outline of the large-span (I) trolley, thus completing the modification from the standard section trolley to the large-span (I) trolley. When it is necessary to convert the large span (one) trolley into a large span (two) trolley, it is only necessary to replace the first crossbeam widening section, the second crossbeam widening section, the third crossbeam widening section, the second shear frame, replace the template and some columns in the middle position of the top formwork, and shorten the distance between the two sets of gantry frames to complete the conversion.

[0050] like Figure 6As shown, the assembly method of the large span (three) trolley is a double-wing outward expansion type. Based on the large span (two) trolley, the two sets of three pairs of masts are restored to one set of six pairs of masts. Extended crossbeams and mast legs are added to both sides of the mast, and the top formwork is replaced with a size type suitable for the building boundary and outline of the large span (three), thus completing the conversion from the large span (two) trolley to the large span (three) trolley.

[0051] like Figure 7 As shown, the assembly method of the large span (four), large span (five), and emergency stopping lane trolley is a single-wing outward expansion type. Among them, the large span (five) and emergency stopping lane trolley can be shared, so the emergency stopping lane trolley will not be described in detail. When modifying from the large span (three) trolley to the large span (four) trolley, the span and height of the trolley are further reduced. If the span is <20m, the third crossbeam is removed. One side of the extension crossbeam and gantry support leg are removed, and the other side is replaced with a suitable extension crossbeam. Some columns are replaced, and the two templates near the middle of the top formwork are replaced to complete the modification of the large span (four) trolley. Since the large span (five) and large span (four) are similar in size, it is only necessary to remove the extension section in the extension crossbeam and adjust the movable support rod to complete the modification of the large span (five) trolley.

[0052] like Figure 8 and Figure 9 As shown, the assembly method for both the large span (six) and large span (seven) trolleys is a single-assembly combination. New components include the first crossbeam extension section 22, the second crossbeam extension section 23, the third crossbeam 25, the third crossbeam extension section 24, the third gantry 25, the column 9, the diagonal brace, and the top formwork. After debugging and verification, the large span (six) trolley is modified. The large span (seven) trolley is similar to the large span (six) trolley; only the template in the middle of the top formwork needs to be replaced, and the movable support rods adjusted, to complete the modification.

[0053] like Figure 10 As shown, the large-span (eight) trolley is similar to the standard section trolley, and the assembly method is a conventional gantry type. Based on the large-span (seven) trolley, the third crossbeam is removed, and the extension sections of the first and second crossbeams, a small number of columns, top formwork, and the excess first gantry are replaced. After debugging and verification, the large-span (eight) trolley modification can be completed.

[0054] Example 2

[0055] Based on the actual situation, the mined tunnel is divided into north and south sections, with 10 different cross-sectional types for the main tunnel. Large spans (I) to (V) are located on the north side, large spans (VI) to (VIII) on the south side, and the standard section and emergency stopping lane are located in the middle of the main tunnel. Two solutions can be adopted on site:

[0056] Option 1: Deploy two trolleys, which will be used to carry out construction and modifications from the north and south ends toward the center.

[0057] Option 2: Use four trolleys for construction. Due to the long cross-sectional distance of the standard section, two trolleys will be dedicated to the secondary lining construction of the standard section, while the other two will be modified and constructed from the north and south ends towards the middle.

[0058] For ease of description, the trolley deployed on the north side will be referred to as Trolley A, and the trolley on the south side will be referred to as Trolley B. The following detailed operating steps will be illustrated using the first scheme as an example:

[0059] After the initial support, invert arch, and secondary lining reinforcement construction of the S1 cut-and-cover tunnel are completed, the secondary lining trolleys are assembled inside the tunnel, and trolleys A and B are converted into standard section trolleys. Through precise measurement, support blocks and tracks are laid at designated locations according to the trolley track gauge requirements, and the gantry assembly and formwork system are assembled from bottom to top, followed by standard section secondary lining construction.

[0060] After the standard section of the S2 north tunnel is completed, the trolley A will be modified into a large-span (I) trolley, based on the standard section trolley, in the manner described above. This process requires replacing 33% of the components and adding 58% of the components. Only a small piece of the top formwork and some columns will be replaced, and the two frames will be laterally reduced. Only 9% of the components will be replaced, and the large-span (I) trolley will be modified into a large-span (II) trolley to complete the secondary lining construction of the large-span (II) area.

[0061] S3. Revert the large-span (II) trolley from two sets of three-pair gantry frames to one set of six-pair gantry frames. Add extension beams and gantry support legs to both sides of the gantry frames. Replace the top formwork and beams. Replace 33% of the components and add 39% of the components to complete the conversion from the large-span (II) trolley to the large-span (III) trolley.

[0062] After the construction of the S4 (three) section is completed, remove the third crossbeam and one side extension crossbeam and support legs, and replace the other side with a suitable extension crossbeam. Replace some columns and replace the two formwork panels near the middle of the top formwork. Replace 15% of the components and dismantle 15% of the components to complete the modification of the large span (four) trolley. Since the large span (five) is similar in size to the large span (four), only the extension section in the extension crossbeam needs to be removed and the movable support rod adjusted. The modification of the large span (five) trolley can be completed by replacing only 5% of the components.

[0063] After the completion of the standard section of the S5 south tunnel, the trolley B will be modified into a large-span (six) trolley based on the standard section trolley. This process requires replacing 20% ​​of the components and adding 50% of the components. Both the large-span (six) and large-span (seven) trolleys are assembled using a single-assembly method. The modification from the large-span (six) and large-span (seven) trolleys only requires replacing the template in the middle of the top formwork and adjusting the movable support rods; only 5% of the components need to be replaced.

[0064] After the completion of the construction of the S6 (Seven) area, the third crossbeam is removed from the S6 (Seven) trolley, and a small number of crossbeams, columns, top formwork, and excess first gantry are replaced. During this process, 18% of the components need to be replaced and 25% need to be dismantled. After debugging and verification, the S6 (Eight) trolley modification is completed.

[0065] The application of this technology has promoted the development and innovation of multi-section, large-span secondary lining trolley installation and modification in mined tunnels, contributing to technological progress in related fields.

[0066] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A multi-section large-span tunnel secondary lining trolley, the multi-section comprising a standard three-lane section, an emergency stopping belt and a large span, characterized in that: The application relates to a tunnel construction vehicle, which comprises a portal assembly, a formwork system and a walking system; the portal assembly comprises a first portal (1) and a second portal (2), the top of the first portal (1) and the second portal (2) is connected with a first cross beam (3) and a second cross beam (4), a group of first longitudinal beams (5) is evenly arranged between the first cross beam (3) and the second cross beam (4), the second portal (2) is provided with a second longitudinal beam (6) and a shear frame (8) from top to bottom; the formwork system comprises a top formwork (12), a side formwork (13) and a bottom formwork (14), the top formwork (12) is supported on the second cross beam (4) through a stand column (9), the side formwork (13) is hingedly connected with the first portal (1) and the second portal (2) through a group of movable supporting rods (15); the walking system comprises a first supporting leg (10), a second supporting leg (11) and a steel track (16) arranged on a inverted arch, the lower ends of the first supporting leg (10) and the second supporting leg (11) are symmetrically arranged on the two sides of the steel track (16).

2. The multi-face large-span tunnel secondary lining trolley according to claim 1, characterized in that: The second cross beam (4) is slidably connected on the first cross beam (3) through the first longitudinal beam (5), a translation oil cylinder is arranged between the first cross beam (3) and the structure below and the first longitudinal beam (5) and the structure above, and the translation oil cylinder can be horizontally slid to make fine adjustment.

3. The multi-face large-span tunnel secondary lining trolley according to claim 1, characterized in that: A lifting oil cylinder (26) is arranged on the second supporting leg (11), and a walking motor and a roller are arranged at the bottom of the second supporting leg (11).

4. The multi-face large-span tunnel secondary lining trolley according to claim 1, characterized in that: When the span of the multi-section tunnel is greater than or equal to 20m, a third longitudinal beam (7) is arranged on the second portal (2).

5. The multi-face large-span tunnel secondary lining trolley according to claim 1, characterized in that: The first portal (1) is a steel structure provided with a ventilation pipe hole, and the second portal (2) is a structure without a ventilation pipe hole.

6. A retrofitting method for the multi-surface large-span tunnel two-formwork trolley according to any one of claims 1-5, characterized in that, The application further discloses a tunnel construction vehicle modification method, which comprises the following steps: S1, identifying the target type of a current tunnel section; S2, determining a corresponding trolley assembly mode according to the span and height parameters of the target section, wherein the assembly mode comprises a conventional portal type, a single assembly type, a double assembly type, a single wing outward expansion type and a double wing outward expansion type; the conventional portal type comprises at least six pairs of portal assemblies, and the six pairs of portal assemblies are arranged at equal intervals along the longitudinal direction of the tunnel; each adjacent two portal assemblies are connected through a group of second longitudinal beams (6), third longitudinal beams (7) and shear frames (8); S3, reserving basic components suitable for the target section in the current trolley; replacing, adding or removing part of the portal, the cross beam, the longitudinal beam, the shear frame, the stand column or the formwork component, and adjusting the connection relationship between the components; S4, debugging and checking the overall size, stability and function of the modified trolley, and completing the modification.

7. A retrofit method as claimed in claim 6, characterized in that: When the assembling mode adopts single-pieced combination, it specifically includes: a regular portal frame, a wing part is extended outwards from the side of the regular portal frame through a first extension member, the first extension member includes a third portal frame (25), the top of the third portal frame (25) is connected with the first cross beam (3) and the second cross beam (4) through a first cross beam extension section (22) and a second cross beam extension section (23) respectively, a third cross beam (26) is arranged above the second cross beam (4), the third cross beam (26) expands the lateral width through a third cross beam extension section (24) on one side, and the third cross beam (26) and the third cross beam extension section (24) are connected with a top die (12) through a stand column (9).

8. A retrofit method as claimed in claim 6, characterized in that: When the assembling mode adopts double-pieced combination, it specifically includes: a group of six pairs of portal frames is separated into two groups of three pairs of portal frames; a third cross beam (17) and a second shear frame (18) are additionally arranged; a first cross beam widening section (19), a second cross beam widening section (20) and a third cross beam widening section (21) are additionally arranged on the first cross beam (3), the second cross beam (4) and the third cross beam (17) respectively; part of the stand columns (9) are increased or lengthened; and the bottom die (14) is replaced by a size suitable for the cross-sectional profile of large span.

9. A retrofit method as claimed in claim 6, characterized in that: When the assembling mode adopts double-wing outward expansion, it specifically includes: a regular portal frame, an extension cross beam and a portal frame leg are additionally arranged on both sides of the regular portal frame; and the top die (12) is replaced by a size suitable for the cross-sectional profile of large span.

10. A retrofit method for use in a method as claimed in claim 9, characterized in that: When the assembling mode adopts single-wing outward expansion, it specifically includes: the third cross beam (17) of the double-wing outward expansion portal frame is removed, the extension cross beam and the portal frame leg on one side are removed, the other side is replaced by a suitable extension cross beam, part of the stand columns (9) are replaced, and two die plates close to the middle position of the top die (12) are replaced.

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