A new type of precast invert block structure for tunnels

Abstract

The present invention provides a novel precast invert block structure for tunnels, which relates to precast invert blocks for tunnels and includes a precast invert. A bottom formwork is provided on the inner bottom wall of the precast invert, and side formworks are provided on both side surfaces of the precast invert. A reinforcing steel plate is fixedly installed on one side surface of each side formwork, and end formworks are fixedly installed on both outer sides of the bottom formwork. The secondary lining invert part, the invert backfill part, and the road surface base layer are integrally precast into a whole through the precast invert, and all invert construction can be completed by prefabricating and assembling the precast invert components at one time; the enlarged bolt holes greatly improve the connection success rate between precast blocks and enhance the adaptability to the planar alignment; the uniformly distributed circular holes make the overall stress of the precast components more reasonable, avoid the need for in-situ casting on both sides, improve the construction efficiency, and ensure better construction quality. Moreover, it avoids the need for two assemblies, realizes low-carbon environmental protection, and has a high degree of industrialization.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel precast invert blocks, and specifically to a novel structure of tunnel precast invert blocks. Background Art

[0002] The invert is a reverse arch structure arranged at the bottom of the tunnel to improve the stress conditions of the upper support structure. It is one of the main components of the tunnel structure. On the one hand, it effectively transfers the formation pressure from the upper part of the tunnel or the load on the road surface to the ground through the tunnel side wall structure, and also effectively resists the reaction force transmitted from the lower strata of the tunnel. The invert and the secondary lining form the whole tunnel, increasing the structural stability.

[0003] In the existing construction of the invert, two in-situ castings are involved. One is the construction of the post-cast strip; the other is the construction of the invert backfill. Although partial carbon reduction and environmental protection are achieved, the construction efficiency is the same as that of in-situ casting, the industrialization level is low, and the construction quality is difficult to control. Moreover, two assemblies are involved in the construction process of the invert. One is the assembly of the outer lining segments; the other is the assembly of the precast blocks for the invert backfill. Although carbon reduction and environmental protection are maximally achieved, the construction efficiency is not maximized, and the stress concentration at the top and bottom of the columns in the middle chamber is significant, which is not conducive to the force-bearing of the overall structure. Summary of the Invention

[0004] The purpose of the present invention is to provide a novel structure of tunnel precast invert blocks. To solve the problems that two in-situ castings are involved in the construction process of the invert. One is the construction of the post-cast strip; the other is the construction of the invert backfill. Although partial carbon reduction and environmental protection are achieved, the construction efficiency is the same as that of in-situ casting, the industrialization level is low, and the construction quality is difficult to control. Moreover, two assemblies are involved in the construction process of the invert. One is the assembly of the outer lining segments; the other is the assembly of the precast blocks for the invert backfill. Although carbon reduction and environmental protection are maximally achieved, the construction efficiency is not maximized, and the stress concentration at the top and bottom of the columns in the middle chamber is significant, which is not conducive to the force-bearing of the overall structure.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] A tunnel precast invert block device to improve the above problems.

[0007] Specifically, the present invention is as follows:

[0008] It includes a precast inverted arch. A bottom formwork is provided on the inner bottom wall of the precast inverted arch. Side formworks are provided on both side surfaces of the precast inverted arch. A reinforcing steel plate is fixedly installed on one side surface of each side formwork. End formworks are fixedly installed on both outer sides of the bottom formwork. Through holes are provided on both sides of each end formwork. Horizontal reinforcing bars are fixedly installed on the inner walls of the through holes. A cast-in-place secondary lining is fixedly installed on the upper surface of the bottom formwork. The horizontal reinforcing bars are transversely connected to the cast-in-place secondary lining. A fish-belly hole is provided on one side surface of the side formwork. A connection groove is provided on the upper surface of the side formwork. A cavity is provided on the inner bottom wall of the bottom formwork. A connection mechanism is fixedly installed on the inner side wall of the connection groove.

[0009] As a preferred technical solution of the present invention, the fish-belly hole is composed of a plurality of holes with different sizes, and the radius of the holes is between 0.35 m and 0.55 m. The bottom width of the bottom formwork is 9.34 m, the top width is 7.9 m, and the highest point in the middle is 1.84 m. Weather-resistant steel plates are symmetrically embedded at the top of the side formwork. The connection groove is provided on the weather-resistant steel plate.

[0010] As a preferred technical solution of the present invention, the number of the connection grooves is four, and they are grouped in pairs. M27 bolts are fixedly installed on the inner side wall of one group of the connection grooves. The connection mechanism includes a bolt body. The bolt body is fixedly installed on the inner side wall of the other group of the connection grooves. A movable tube is threadedly connected to the surface of the bolt body. A guiding groove is provided on the outer arc surface of the movable tube.

[0011] As a preferred technical solution of the present invention, a guiding support plate is slidably connected to the surface of the guiding groove. Rotating pins A are fixedly installed on both sides of the upper surface of the guiding support plate. One side of the rotating pin A is movably clamped with a first fixing rod through a rotating shaft. One end of the first fixing rod is movably clamped with a second fixing rod through a rotating shaft. One end of the second fixing rod is movably clamped with a rotating pin B through a rotating shaft.

[0012] As a preferred technical solution of the present invention, a pushing support plate is fixedly installed on the lower surface of the rotating pin B. The lower surface of the pushing support plate is fixedly installed on the top of the outer arc surface of the movable tube. A rotating push rod penetrates through one end of the movable tube. A fixed sleeve is threadedly connected to one end of the bolt body.

[0013] As a preferred technical solution of the present invention, the number of the guiding grooves is four. Guiding support plates are slidably connected to the inner side walls of all the four guiding grooves. A positioning pin is movably clamped on one side surface of the second fixing rod. Positioning holes are provided in the inner part of one group of the connection grooves.

[0014] As a preferred technical solution of the present invention, the number of the positioning holes is four, which are clamped and adapted to the four positioning pins. The number of the M27 bolts is four, and they are fixedly installed in the other group of connecting grooves. A grouting cavity with a reserved amount of 0.5 m is provided at the center position of the bottom of the cavity.

[0015] As a preferred technical solution of the present invention, the inside of the fish-belly hole is a hollow structure. The number of the horizontal steel bars is several, and they are fixed on the cast-in-place secondary lining.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. By prefabricating the inverted arch, the inverted arch part of the secondary lining, the inverted arch backfill part and the road surface base layer are prefabricated into a whole. The construction of the entire inverted arch can be completed by prefabricating and assembling the precast inverted arch components once. The enlarged bolt holes greatly improve the connection success rate between the precast blocks and enhance the adaptability of the planar alignment. The uniformly distributed circular holes make the overall stress of the precast components more reasonable, avoiding the need for in-situ casting on both sides, improving the construction efficiency, ensuring the construction quality, and avoiding the need for two assemblies, achieving low carbon environmental protection and high industrialization.

[0018] 2. Through the connecting mechanism, the rotating push rod rotates to push the fixing rod, which originally is horizontal. By rotation, it is jacked up and clamped on the inner wall of the through hole. The positioning pin is rotated and inserted into the positioning hole to further fix the precast slab. And by reverse rotation, the arched fixing rod can be rotated back to the horizontal state, and due to reverse rotation, the positioning pin is disengaged from the positioning hole and comes into contact and is fixed, thus realizing quick disassembly. This avoids the situation that ordinary bolts appear rusty due to long-term fixation and being eroded by rain and humidity, and also avoids the difficulty of removing the bolts due to rust spots during disassembly, improving the disassembly efficiency and facilitating fixation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the tunnel precast inverted arch block structure given in Example 1 of the present invention;

[0020] Figure 2 It is a structural example diagram of the weathering steel plate given in Example 1 of the present invention;

[0021] Figure 3 It is a schematic diagram of the overall implementation structure of the tunnel precast inverted arch block structure given in Example 2 of the present invention;

[0022] Figure 4 It is a schematic diagram of the partial structure of the tunnel precast inverted arch block structure given in Example 2 of the present invention;

[0023] Figure 5 It is a schematic diagram of the connecting mechanism structure of the tunnel precast inverted arch block structure given in Example 2 of the present invention;

[0024] Figure 6 This is the schematic plan view of the precast invert block structure for Example 2 of the present invention;

[0025] Figure 7 This is the tunnel precast invert block structure for Example 2 of the present invention Figure 6 The enlarged structure schematic diagram at position A in it.

[0026] In the figure: 1, precast invert; 2, bottom formwork; 3, side formwork; 4, end formwork; 5, horizontal planted bars; 6, cast-in-place secondary lining; 7, fish-belly hole; 8, connecting groove; 9, cavity; 10, connecting mechanism; 101, bolt body; 102, movable pipe; 103, guiding groove; 104, guiding support plate; 105, rotating pin A; 106, first fixing rod; 107, second fixing rod; 108, rotating pin B; 109, pushing support plate; 1010, rotating push rod; 1011, fixed sleeve; 1012, positioning pin; 11, M27 bolt; 12, positioning hole. Specific embodiments

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention.

[0028] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed present invention, but merely represents some embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0029] It should be noted that, without conflict, the embodiments in the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0030] It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0031] Example 1;

[0032] Refer to Figure 1 and Figure 2 , which shows an example solution for the composition of the tunnel precast invert block given in this example.

[0033] As can be seen from the figure, the tunnel precast invert block 20 given in this example adopts an integral fish-belly type structure, and innovatively prefabricates the secondary lining invert part, the invert backfill part and the road surface base course into a whole.

[0034] On this basis, in this example, uniformly distributed circular holes 21 are further adopted inside the precast inverted arch. Preferably, the radii of the holes here range from 0.35 m to 0.55 m. Through these circular holes with different diameters and uniform distribution, not only the structural stress distribution is improved, but also the effect of completing the inverted arch construction by one-time precast assembly is achieved.

[0035] Combined with Figure 2 As shown, in this example, corresponding weathering steel plates 22 are symmetrically embedded at the top of the precast inverted arch blocks of this tunnel. At the same time, enlarged screw holes 221 are configured on the weathering steel plates 22, so that the precast blocks can be longitudinally connected by bolts, thereby improving the connection success rate between the precast blocks and ensuring the smoothness of the plane alignment.

[0036] Preferably, multiple groups of enlarged screw holes 221 with different specifications are configured on the weathering steel plates 22 in this example to meet different requirements and ensure the stable reliability of the connection.

[0037] As an example, two groups of enlarged screw holes 221 are adopted in the illustrated scheme, with two enlarged screw holes in each group, and the distribution structures of these two enlarged screw holes are the same. Among them, the two enlarged screw holes in the first group located in the upper part are distributed horizontally in the length direction; the two enlarged screw holes in the second group located in the lower part are distributed vertically in the length direction.

[0038] As a further innovation, corresponding reinforcing bars 23 are embedded at the transverse two ends of the precast inverted arch blocks of this tunnel. Thus, in the transverse direction, the precast inverted arch blocks of this tunnel can be connected to the cast-in-place secondary lining through the pre-embedded reinforcing bars in advance, greatly improving the application convenience of the precast inverted arch blocks of the tunnel.

[0039] As a further innovation, a corresponding grouting cavity 24 is reserved at the center position of the bottom of the precast block of the precast inverted arch of this tunnel for grouting.

[0040] All the inverted arch construction can be completed by one-time precast assembly of the precast inverted arch components given in this example; the enlarged bolt holes greatly improve the connection success rate between the precast blocks and enhance the adaptability of the plane alignment; the uniformly distributed circular holes make the overall force of the precast components more reasonable.

[0041] Example Two;

[0042] Please refer to Figures 3 to 7The present invention provides a technical solution: a novel prefabricated tunnel arch block structure, comprising a prefabricated arch 1, the inner bottom wall of the prefabricated arch 1 is provided with a bottom template 2, both sides of the prefabricated arch 1 are provided with side templates 3, one side surface of the side template 3 is fixedly installed with a reinforcing steel plate, both sides of the outer side of the bottom template 2 are fixedly installed with end templates 4, both sides of the end template 4 are provided with through holes, the inner wall of the through hole is fixedly installed with transverse embedded steel bars 5, the upper surface of the bottom template 2 is fixedly installed with a cast-in-place second lining 6, the transverse embedded steel bars 5 are transversely connected to the cast-in-place second lining 6, and the side templates are fixedly installed with a cast-in-place second lining 6. A fish belly hole 7 is opened on one side surface of the plate 3, a connecting groove 8 begins to be opened on the upper surface of the side template 3, a cavity 9 is provided on the inner bottom wall of the bottom template 2, and a connecting mechanism 10 is fixedly installed on the inner wall of the connecting groove 8. The fish belly hole 7 is composed of a plurality of holes of different sizes, and the hole radius is set between 0.35m and 0.55m. The bottom template 2 has a bottom width of 9.34m, a top width of 7.9m, and a maximum of 1.84m in the middle. The top of the side template 3 is symmetrically embedded with 0.2m of pre-embedded holes, and the holes are weather-resistant steel plates, and the connecting groove 8 is opened on the weather-resistant steel plates.

[0043] It should be noted that the prefabricated invert 1 prefabricates the secondary lining invert part, the invert backfill part and the road base into a whole, adopting an integral fish belly structure, with a bottom width of 9.34m, a top width of 7.9m, a maximum of 1.84m in the middle, and a single block longitudinal length of 1.0m. Different from the existing prefabricated component form, the prefabricated invert uses uniformly distributed circular holes inside, with hole radius ranging from 0.35m to 0.55m; the top is symmetrically embedded in the form of 0.2m symmetrical embedded parts, the weather-resistant steel plate prefabricated this time, with enlarged screw holes configured on it and M2711 bolts connecting each prefabricated block longitudinally; the prefabricated invert block is connected to the cast-in-place secondary lining horizontally through pre-embedded reinforcement; a grouting cavity at the bottom center of the prefabricated block is reserved at the bottom center of 0.5m for grouting.

[0044] Embodiment three;

[0045] like Figure 3 and Figure 5As shown, as a preferred embodiment, on the basis of the above method, further, the number of the connecting grooves 8 is four, and they are grouped in pairs. M27 bolts 11 are fixedly installed on the inner side walls of one group of the connecting grooves 8. The connecting mechanism 10 includes a bolt body 101, and the bolt body 101 is fixedly installed on the inner side walls of the other group of the connecting grooves 8. A movable tube 102 is threadedly connected to the surface of the bolt body 101. A guiding groove 103 is formed on the outer arc surface of the movable tube 102. A guiding support plate 104 is slidably connected to the surface of the guiding groove 103. Rotating pins A105 are fixedly installed on both sides of the upper surface of the guiding support plate 104. One side of the rotating pin A105 is movably clamped with a first fixing rod 106 through a rotating shaft. One end of the first fixing rod 106 is movably clamped with a second fixing rod 107 through a rotating shaft. One end of the second fixing rod 107 is movably clamped with a rotating pin B108 through a rotating shaft. A pushing support plate 109 is fixedly installed on the lower surface of the rotating pin B108. The lower surface of the pushing support plate 109 is fixedly installed on the top of the outer arc surface of the movable tube 102. One end of the movable tube 102 penetrates and is connected with a rotating push rod 1010. One end of the bolt body 101 is threadedly connected with a fixing sleeve 1011. The number of the guiding grooves 103 is four, and the guiding support plates 104 are slidably connected to the inner side walls of all the four guiding grooves 103. A positioning pin 1012 is movably clamped on one side surface of the second fixing rod 107. Positioning holes 12 are formed in the inner part of one group of the connecting grooves 8.

[0046] Exemplarily, during grouting, as described above, the connecting grooves 8 on the surface of the weather-resistant steel plate at the top end of the side form 3 are used to fix the precast slab at the longitudinal rear end through the M27 11. Both ends of it are fixed through the connecting mechanism 10. The bolt body 101 is rotated into the connecting groove 8, and due to the rotation, the rotating push rod 1010 rotates downward along the thread teeth. One end of the movable tube 102 fixed to one end of the rotating push rod 1010 is pushed by the rotating push rod 1010, so that one end of the movable tube 102 abuts against the inner bottom wall of the through hole. Since the movable tube is of an elastic structure, one end abuts against the inner wall and remains stationary, while the other end still rotates and approaches, which will cause the guiding support plate 104 sliding in the guiding groove 103 to gradually approach the bottom end of the movable tube 102 and remain stationary like the movable tube 102. At this time, the force on the guiding support plate 104 will be transmitted to the rotating pin A105 on the surface. And due to continuous pressing and rotation, the pushing support plate 109 fixed at one end continuously moves forward and makes its vertical fixing rod deflect in angle. At this time, due to the deflection of the second fixing rod 107, the first fixing rod 106 movably clamped by it also deflects to reach the situation of internal expansion. And the positioning pin 1012 on one side of the original second fixing rod 107 is inserted into the positioning hole 12. At this time, the other end of the bolt body 101 is fixed again through the fixing sleeve.

[0047] It should be noted that the connection mechanism 10 rotates the push rod 1011 to push the fixed rod, so that the originally horizontal fixed rod is lifted by rotation, clamped on the inner wall of the through hole, and the positioning pin 1012 is rotated and inserted into the positioning hole to further fix the precast slab. By rotating in the reverse direction, the arched fixed rod can be rotated back to the horizontal state, and due to the reverse rotation, the positioning pin 1012 is disengaged from the positioning hole 12 and comes into contact and is fixed, thus realizing quick disassembly. This avoids the situation that ordinary bolts have rust spots due to being eroded by rain and humidity during long-term fixation, and also avoids the difficulty of removing bolts due to rust spots during disassembly, improves the disassembly efficiency, and is convenient for fixation.

[0048] Embodiment 4;

[0049] The number of positioning holes 12 is four, and they are engaged and adapted to the four positioning pins 1012. The number of M27 bolts 11 is four, and they are fixedly installed in another set of connection grooves 8. A grouting cavity of 0.5 m × 0.07 m is reserved at the center of the bottom of the cavity 9. The inside of the fish-belly hole 7 is a hollow structure. The number of horizontal reinforcing bars 5 is several, and they are fixed on the cast-in-place secondary lining 6.

[0050] Exemplarily, the extended length of the embedded steel bars at the side wall parts of the secondary lining on both sides of the inverted arch should meet the requirements for welding with the circumferential secondary lining steel bars, and the joints should be staggered so that the number of steel bar joints in the same section does not exceed 50% of the total number. The binding of the inverted arch secondary lining steel bars must ensure the spacing, and the layer spacing is ensured by welding positioning steel bars.

[0051] Embodiment 5;

[0052] The solutions in Embodiments 2 to 4 are further introduced below in combination with the specific working methods. See the following description for details:

[0053] When the new tunnel precast inverted arch block structure is specifically used:

[0054] The construction personnel first connect the prefabricated inverted arch block with the prefabricated block at the rear end through the connecting mechanisms 10 at both ends, rotate the bolt body 101 into the connecting groove 8, and rotate the rotating push rod 1010 downward along the thread teeth due to the rotation, and the movable tube 102 fixed at one end of the rotating push rod 1010 is overlapped on the inner bottom wall of the through hole due to the thrust of the rotating push rod 1010. Because the movable tube is an elastic structure, one end overlaps the inner wall and remains stationary, and the other end continues to rotate close to it. This will cause the guide support plate 104 sliding in the guide groove 103 to gradually approach the bottom end of the movable tube 102 and remain stationary like the movable tube 102. At this time, the force of the guide support plate 104 will be transmitted to the rotating pin A105 on the surface, and due to the continuous pressure and rotation, one end is fixedly pushed to the support plate 109 to continue forward and make its vertical fixed rod, resulting in an angular deviation. At this time, due to the deviation of the second fixed rod 107, the first fixed rod 106 that is movably connected to it is also The offset reaches the situation of internal expansion, and the positioning pin 1012 originally on one side of the second fixing rod 107 is inserted into the positioning hole 12. At this time, the other end of the bolt body 101 is fixed again through the fixing sleeve. When the fixing is completed, the prefabricated inverted arch 1 prefabricates the secondary lining inverted arch part, the inverted arch backfill part and the road surface base into a whole, adopts an integral fish belly structure, its bottom width is 9.34m, the top width is 7.9m, the highest in the middle is 1.84m, and the longitudinal length of a single block is 1.0m. Different from the existing prefabricated component form, the prefabricated inverted arch adopts uniformly distributed circular holes inside, and the hole radius varies from 0.35m to 0.55m; the top is symmetrically embedded in the form of 0.2m symmetrical embedded parts, the weather-resistant steel plate prefabricated this time is configured with enlarged screw holes and the prefabricated blocks are longitudinally connected by M2711 bolts; the prefabricated inverted arch block is connected to the cast-in-place second lining horizontally by pre-embedded reinforcement; a grouting cavity at the bottom center of the prefabricated block is reserved at the bottom center of 0.5m to implement grouting.

[0055] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A novel precast invert block structure for tunnels, including a precast invert (1). It is characterized in that: A bottom formwork (2) is provided on the inner bottom wall of the precast invert (1). Side formworks (3) are provided on both side surfaces of the precast invert (1). A reinforcing steel plate is fixedly installed on one side surface of the side formwork (3). End formworks (4) are fixedly installed on both outer sides of the bottom formwork (2). Through holes are provided on both sides of the end formwork (4). Horizontal reinforcing bars (5) are fixedly installed on the inner walls of the through holes. A cast-in-place secondary lining (6) is fixedly installed on the upper surface of the bottom formwork (2). The horizontal reinforcing bars (5) are horizontally connected to the cast-in-place secondary lining (6). A fish-belly hole (7) is provided on one side surface of the side formwork (3). A connecting groove (8) is provided on the upper surface of the side formwork (3). A cavity (9) is provided on the inner bottom wall of the bottom formwork (2). A connecting mechanism (10) is fixedly installed on the inner side wall of the connecting groove (8). The fish-belly hole (7) is composed of a plurality of holes of different sizes, and the radius of the holes is between 0.35 m and 0.55 m. The bottom width of the bottom formwork (2) is 9.34 m, the top width is 7.9 m, and the highest point in the middle is 1.84 m. Weathering steel plates (22) are symmetrically embedded at the top of the side formwork (3). The connecting groove (8) is provided on the weathering steel plate. The number of the connecting grooves (8) is four, and they are grouped in pairs. M27 bolts (11) are fixedly installed on the inner side wall of one group of the connecting grooves (8). The connecting mechanism (10) includes a bolt body (101). The bolt body (101) is fixedly installed on the inner side wall of the other group of the connecting grooves (8). A movable tube (102) is threadedly connected to the surface of the bolt body (101). A guiding groove (103) is provided on the outer arc surface of the movable tube (102).

2. A novel precast invert block structure for tunnels according to claim 1. It is characterized in that: A guiding support plate (104) is slidably connected to the surface of the guiding groove (103). Rotating pins A (105) are fixedly installed on both sides of the upper surface of the guiding support plate (104). One side of the rotating pin A (105) is movably clamped with a first fixing rod (106) through a rotating shaft. One end of the first fixing rod (106) is movably clamped with a second fixing rod (107) through a rotating shaft. One end of the second fixing rod (107) is movably clamped with a rotating pin B (108) through a rotating shaft.

3. A novel precast invert block structure for tunnels according to claim 2. It is characterized in that: A pushing support plate (109) is fixedly installed on the lower surface of the rotating pin B (108). The lower surface of the pushing support plate (109) is fixedly installed on the top of the outer arc surface of the movable tube (102). One end of the movable tube (102) is penetrated and connected with a rotating push rod (1010). One end of the bolt body (101) is threadedly connected with a fixed sleeve (1011).

4. A novel precast invert block structure for tunnels according to claim 2. It is characterized in that: The number of the guiding grooves (103) is four, and guiding support plates (104) are slidably connected to the inner side walls of the four guiding grooves (103). A positioning pin (1012) is movably clamped on one side surface of the second fixing rod (107), and positioning holes (12) are formed in the inner parts of one group of the connecting grooves (8).

5. A novel precast invert block structure for a tunnel according to claim 4, characterized in that: The number of the positioning holes (12) is four and is in clamping fit with the four positioning pins (1012). The number of the M27 bolts (11) is four and is fixedly installed in the other group of the connecting grooves (8). A grouting cavity of 0.5 m×0.07 m is reserved at the central position of the bottom of the cavity (9).

6. A novel precast invert block structure for a tunnel according to claim 1, characterized in that: The inside of the fish-belly hole (7) is a hollow structure. The number of the transverse steel bars (5) is several and is fixed on the cast-in-place secondary lining (6).

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