Accurate installation technology for preventing the secondary lining steel bars from falling in extra-large-span flat tunnels

Abstract

The invention relates to an accurate installation process for preventing the second lining steel bars from falling in a super-large-span flat tunnel, and belongs to the technical field of tunnel second lining construction. The arch top position is divided into a plurality of second lining steel bar installation areas from the outside to the inside along the tunnel with a length L as a stepping distance, and a positioning support mechanism is arranged on the plurality of second lining steel bar installation areas. The second lining steel bars are installed in the outermost second lining steel bar installation area, and the first arc-shaped second lining steel bars are respectively installed along the outermost and innermost arc-shaped edges of the second lining steel bar installation area, and then the first straight second lining steel bars are respectively installed along the two straight edges of the second lining steel bar installation area, and the two first straight second lining steel bars are connected as a whole with the two first arc-shaped second lining steel bars, and finally the first straight second lining steel bar and the first arc-shaped second lining steel bar are connected with the positioning support mechanism, so that the problem of uneven force on the supporting positioning steel bars during the entire installation process is avoided, which causes the fracture of the welding points of the supporting positioning steel bars welded at the arch top position, thereby causing the second lining steel bars to still fall.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel secondary lining construction, and in particular relates to an accurate installation process for preventing secondary lining steel bars from falling in extra-large-span flat tunnels. Background Art

[0002] Welded supporting steel bars are used because the protective layer of the lining steel bars at the top of the second lining arch is difficult to control. When pouring concrete, the steel bars of the arch are prone to sinking. Therefore, supporting positioning steel bars are welded at the top of the arch. The steel bars of the arch are tightened by supporting positioning steel bars to prevent the steel bars of the arch from sinking. This prevents the arch lining steel bars from sinking due to force during concrete pouring, affecting the thickness of the protective layer.

[0003] At present, during the construction process of the second lining steel bar anti-falling of the tunnel, after the supporting positioning steel bars are welded at the arch top, when the lining steel bars are installed on the supporting positioning steel bars, they are generally installed in sequence from right to left or from left to right along the arch part of the tunnel. However, when encountering a super-large span flat tunnel, this installation method has some problems: because it is aimed at a super-large span flat tunnel, the number of steel bars required at the arch top of the super-large tunnel will be more than that of an ordinary tunnel, so the gravity of the steel bars at the arch top will be greater. In addition, the angle of the arch top of the flat tunnel is large, which will make the gravity of the steel bars at the arch top This step increases the tendency of the secondary lining steel bars to sink. If the installation is still carried out in sequence from right to left or from left to right, as the number of steel bars increases, during the installation process, the force on the supporting and positioning steel bars at the arched part where the steel bars are installed first will be different from that on the arched part where the steel bars are installed later, resulting in uneven force on the supporting and positioning steel bars during the entire installation process. It is easy to cause the welding points of the supporting and positioning steel bars welded at the arch top to break, resulting in the possibility of the secondary lining steel bars still falling. In this regard, an accurate installation process for preventing the secondary lining steel bars from falling is proposed for extra-large span flat tunnels. Summary of the invention

[0004] In order to solve the above-mentioned problems existing in the prior art, the present invention provides an accurate installation process for preventing the second lining steel bars from falling in extra-large span flat tunnels, which solves the problem in the prior art that the force on the supporting and positioning steel bars at the arched part of the installed steel bars is different from that on the arched part of the later installed steel bars, resulting in uneven force on the supporting and positioning steel bars in the entire installation process, which can easily cause the welding points of the supporting and positioning steel bars welded at the arch top to break.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The accurate installation process of the second lining steel bar anti-falling of the extra-large span flat tunnel includes the following steps:

[0007] S1: Divide the arch top into a number of secondary lining steel bar installation areas along the tunnel from the outside to the inside with a length L as a stepping distance, and set positioning support mechanisms on the plurality of secondary lining steel bar installation areas respectively;

[0008] S2: Install the second lining steel bar in the outermost second lining steel bar installation area, install the first arc-shaped second lining steel bar along the outermost and innermost arc-shaped edges of the second lining steel bar installation area respectively, and then install the first straight second lining steel bar along the two straight edges of the second lining steel bar installation area respectively, connect the two first straight second lining steel bars and the two first arc-shaped second lining steel bars into one, and finally connect the first straight second lining steel bar and the first arc-shaped second lining steel bar to the positioning support mechanism;

[0009] S3: Then, two second arc-shaped second lining steel bars are respectively installed outwardly along the innermost first arc-shaped second lining steel bar and inwardly along the outermost first arc-shaped second lining steel bar with a distance of S, and then a second straight second lining steel bar is respectively installed along both ends of the two second arc-shaped second lining steel bars with a distance of H higher than the first straight second lining steel bar in the vertical direction, and the second straight second lining steel bar is connected with the first arc-shaped second lining steel bar and the second arc-shaped second lining steel bar as a whole, and then the second straight second lining steel bar and the second arc-shaped second lining steel bar are connected with the preset positioning support mechanism, and in this way, two third arc-shaped second lining steel bars and two third straight second lining steel bars, two fourth arc-shaped second lining steel bars and two fourth straight second lining steel bars ... two Nth arc-shaped second lining steel bars and two Nth straight second lining steel bars are continuously installed, and finally an N+1th arc-shaped second lining steel bar and an N+1th straight second lining steel bar are installed on the top of the second lining steel bar installation area, so that the second lining steel bars in the outermost second lining steel bar installation area are evenly stressed during installation;

[0010] S4: Repeat S2 and S3 to install the secondary lining steel bars in the remaining secondary lining steel bar installation areas.

[0011] As a further solution of the present invention, the number of all the straight secondary lining steel bars and the arc-shaped secondary lining steel bars in S4 is the same.

[0012] As a further solution of the present invention, the positioning support mechanism used in S2 and S3 is the same, and the positioning support mechanism includes a supporting part and a locking part. The supporting part is connected to the top wall of the tunnel vault through a limiting piece, and the second lining steel bar is locked with the supporting part through the locking part.

[0013] As a further solution of the present invention, the supporting portion is a steel grille, a plurality of rectangular grooves are provided on the steel grille, and the locking portion is located in the rectangular grooves.

[0014] As a further solution of the present invention, the locking portion includes a vertical rod and a plurality of movable rods, one end of the plurality of movable rods are respectively hinged to the side walls of the rectangular groove, the other ends of the plurality of movable rods are mounted on the same vertical rod through a sliding sleeve, and the other ends of the plurality of movable rods are hinged to the side walls of the sliding sleeve, the sliding sleeve is slidably connected to the vertical rod, and the vertical rod is slidably connected to the top wall of the rectangular groove.

[0015] As a further solution of the present invention, the angle between the two movable rods and the side wall of the rectangular groove close to the top of the tunnel is an acute angle.

[0016] As a further solution of the present invention, the vertical rod is located at the center of the rectangular groove, and the number of movable rods on the same vertical rod is greater than or equal to four.

[0017] As a further solution of the present invention, the connection between the straight second lining steel bars and the curved second lining steel bars in S4 is connected by a grasping mechanism, and the grasping mechanism includes a movable part, a four-claw grasping part and a guide part, one end of the four claws of the four-claw grasping part are evenly hinged on the guide part, and the movable part is slidably mounted on the guide part, and the four claw side walls of the four-claw grasping part are connected to the movable part by a connecting rod, and the two ends of the connecting rod are respectively hinged to the four claw side walls of the four-claw grasping part and the movable part, and the guide part drives the slider to slide along the guide rod of the guide part, and the movable part drives the connecting rod to slide along the four claw side walls of the four-claw grasping part, so that the other ends of the four claws of the four-claw grasping part clamp the connection between the straight second lining steel bars and the curved second lining steel bars.

[0018] As a further solution of the present invention, the four claws of the four-claw grasping portion are provided with a plurality of arc-shaped protrusions for increasing the friction between the straight second lining steel bars and the arc-shaped second lining steel bars and the four-claw grasping portion.

[0019] As a further solution of the present invention, the ends of the four claws of the four-claw grasping portion are pyramid structures.

[0020] The beneficial effects of the present invention are:

[0021] The arch top is divided into several second lining steel bar installation areas from the outside to the inside of the tunnel with a stepping distance of length L, and positioning support mechanisms are respectively set on several second lining steel bar installation areas, and the second lining steel bars are installed in the outermost second lining steel bar installation area, and the first arc-shaped second lining steel bars are respectively installed along the outermost and innermost arc-shaped edges of the second lining steel bar installation area, and then the first straight second lining steel bars are respectively installed along the two straight edges of the second lining steel bar installation area, and the two first straight second lining steel bars are connected with the two first arc-shaped second lining steel bars as a whole. Finally, the first straight second lining steel bars and the first arc-shaped second lining steel bars are connected to the positioning support mechanism, and the above steps are repeated to install the second lining steel bars in the remaining second lining steel bar installation areas, so as to avoid uneven force on the supporting positioning steel bars during the entire installation process, which can easily cause the welding points of the supporting positioning steel bars welded at the arch top to break, thereby causing the second lining steel bars to still fall. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the overall construction area of ​​the extra-large span flat tunnel of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the positioning support mechanism of the present invention;

[0025] Figure 3 A top view of the grabbing mechanism of the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of the grabbing mechanism of the present invention.

[0027] Description of main component symbols:

[0028] In the figure: 1. positioning support mechanism; 11. support part; 12. locking part; 2. extra-large span flat tunnel; 3. grabbing mechanism; 31. movable part; 32. four-claw grabbing part; 33. guide part; 34. connecting rod. DETAILED DESCRIPTION

[0029] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0030] See also Figure 1-4 This embodiment provides an accurate installation process for preventing the second lining steel bar from falling in a large-span flat tunnel 2, including the following steps:

[0031] S1: Divide the arch top into several secondary lining steel bar installation areas along the tunnel from outside to inside with a stepping distance of length L, and set a positioning support mechanism 1 on each of the secondary lining steel bar installation areas. The length L here needs to be determined according to the equipment, personnel and construction standards during construction;

[0032] S2: Install the second lining steel bars in the outermost second lining steel bar installation area, install the first arc-shaped second lining steel bars along the outermost and innermost arc-shaped edges of the second lining steel bar installation area respectively, and then install the first straight second lining steel bars along the two straight edges of the second lining steel bar installation area respectively, connect the two first straight second lining steel bars with the two first arc-shaped second lining steel bars as a whole, and finally connect the first straight second lining steel bars and the first arc-shaped second lining steel bars to the positioning support mechanism 1; the first arc-shaped second lining steel bars here are installed along the outermost and innermost sides of the first second lining area of ​​the tunnel, and the arc-shaped area formed by the two first straight second lining steel bars and the two first arc-shaped second lining steel bars is the largest. Next, in the same second lining steel bar installation area, the area formed by the straight second lining steel bars and the arc-shaped second lining steel bars decreases successively, such as Figure 1 As shown;

[0033] S3: Then, two second arc-shaped second lining steel bars are installed outwardly along the innermost first arc-shaped second lining steel bar and inwardly along the outermost first arc-shaped second lining steel bar with a distance of S, and then a second straight second lining steel bar is installed along both ends of the two second arc-shaped second lining steel bars with a vertical length higher than the first straight second lining steel bar H, and the second straight second lining steel bar is connected to the first arc-shaped second lining steel bar and the second arc-shaped second lining steel bar as a whole, and then the second straight second lining steel bar and the second arc-shaped second lining steel bar are connected to the preset positioning support mechanism 1, and in this way, two third arc-shaped second lining steel bars and two third straight second lining steel bars, two fourth arc-shaped second lining steel bars and two fourth straight second lining steel bars ... two Nth arc-shaped second lining steel bars and two Nth straight second Lining steel bars, and finally install an N+1th arc-shaped second lining steel bar and an N+1th straight second lining steel bar on the top of the second lining steel bar installation area, so that the second lining steel bars in the outermost second lining steel bar installation area are evenly stressed during installation; the S length and H length mentioned here are related to the thickness and bearing capacity of the steel bars, respectively. Construction personnel need to determine the S length and H length according to the size of the tunnel, the thickness of the steel bars and the bearing capacity, and also need to ensure that the whole formed by all the straight second lining steel bars and arc-shaped second lining steel bars is sufficient to support the tunnel as a whole; in addition, in order to facilitate the description of the last arc-shaped second lining steel bar and straight second lining steel bar, N and N+1 are used here, and N+1 only represents the last arc-shaped second lining steel bar and straight second lining steel bar;

[0034] S4: Repeat S2 and S3 to install the secondary lining steel bars in the remaining secondary lining steel bar installation areas.

[0035] At present, during the construction process of the tunnel second lining steel bar anti-falling, after the supporting positioning steel bars are welded at the arch top, when the lining steel bars are installed on the supporting positioning steel bars, they are generally installed in sequence from right to left or from left to right along the tunnel arch part. However, when encountering a super-large span flat tunnel 2, this installation method has some problems: because it is aimed at a super-large span flat tunnel 2,

[0036] The extra-large span flat tunnel 2 has a larger span and a larger angle of the arched part, so the requirements for the secondary lining steel bars will be higher, and the number of steel bars required at the arch of the extra-large tunnel will be more than that of the ordinary tunnel, so the gravity of the steel bars at the arch will be greater. In addition, the angle of the arch of the flat tunnel is larger, which will make the gravity of the steel bars at the arch further increase the tendency of the secondary lining steel bars to sink. At this time, if the installation is still carried out from right to left or from left to right in sequence, as the number of steel bars increases, during the installation process, the support and positioning steel bars at the arched part where the steel bars are installed first will be subjected to different forces from the support and positioning steel bars at the arched part where the steel bars are installed later, resulting in uneven force on the support and positioning steel bars during the entire installation process, which can easily cause the welding points of the support and positioning steel bars welded at the arch to break, thereby causing the secondary lining steel bars to still have the possibility of falling.

[0037] In order to solve the above problem, in this embodiment, the arch top is first divided into several second lining steel bar installation areas along the tunnel from the outside to the inside with a step distance of length L, and a positioning support mechanism 1 is set on each of the several second lining steel bar installation areas, and the second lining steel bars are installed in the outermost second lining steel bar installation area, and the first arc-shaped second lining steel bars are installed along the outermost and innermost arc-shaped edges of the second lining steel bar installation area respectively, and then the first straight second lining steel bars are installed along the two straight edges of the second lining steel bar installation area respectively, and the two first straight second lining steel bars are connected to the two first arc-shaped second lining steel bars as a whole, and finally the first straight second lining steel bars and the first arc-shaped second lining steel bars are connected to the positioning support mechanism 1, and then two second arc-shaped second lining steel bars are installed outwardly along the innermost first arc-shaped second lining steel bar and inwardly along the outermost first arc-shaped second lining steel bar with a length S as a distance, and then a second straight second lining steel bar is installed along both ends of the two second arc-shaped second lining steel bars with a length H higher than the first straight second lining steel bar in the vertical direction. The straight second lining steel bar is connected to the first arc-shaped second lining steel bar and the second arc-shaped second lining steel bar as a whole, and then the second straight second lining steel bar and the second arc-shaped second lining steel bar are connected to the preset positioning support mechanism 1. In this way, continue to install two third arc-shaped second lining steel bars and two third straight second lining steel bars, two fourth arc-shaped second lining steel bars and two fourth straight second lining steel bars... two Nth arc-shaped second lining steel bars and two Nth straight second lining steel bars, and finally install an N+1th arc-shaped second lining steel bar and an N+1th straight second lining steel bar on the top of the second lining steel bar installation area, so that the second lining steel bars in the outermost second lining steel bar installation area are evenly stressed during installation, repeat the above steps, and install the second lining steel bars in the remaining second lining steel bar installation areas respectively, so as to avoid uneven stress on the supporting positioning steel bars during the entire installation process, which can easily cause the welding points of the supporting positioning steel bars welded at the arch top to break, thereby causing the second lining steel bars to still fall, and this method can enable construction personnel to accurately complete the installation process of the second lining steel bars.

[0038] During the construction of the extra-large span flat tunnel 2, in order to ensure that the second lining steel bars can be evenly stressed, thereby reducing the risk of the second lining steel bars falling, in one embodiment, the number of all straight second lining steel bars and arc-shaped second lining steel bars in S4 is the same, because every two straight second lining steel bars and two arc-shaped second lining steel bars form an arc-shaped support area, and the arc-shaped support area decreases successively. When it is reduced to the minimum, the number of all straight second lining steel bars and arc-shaped second lining steel bars is the same, which can ensure that the second lining steel bars can be evenly stressed, and at the same time all the arc-shaped support areas will form a solid whole, reducing the risk of the second lining steel bars falling.

[0039] It is worth mentioning that after the second lining steel bars are installed, the overall weight formed by the second lining steel bars is heavier and there is a tendency to move downward. At present, the second lining steel bars are mostly connected to the inner wall of the tunnel by bolts. However, since the environment in the tunnel is prone to moisture, moisture will cause the bolts to loosen, and eventually the second lining steel bars may fall as a whole. In order to solve this problem, in one embodiment, the positioning support mechanism 1 used in S2 and S3 is the same, and the positioning support mechanism 1 includes a support portion 11 and a locking portion 12. The support portion 11 is connected to the top wall of the tunnel arch through a limit piece, and the second lining steel bars and the support portion 11 are locked by the locking portion 12.

[0040] In order to ensure that the support portion 11 can not only support the secondary lining steel bars, but also ensure that the support portion 11 can be removed and reused after use, in one embodiment, the support portion 11 is a steel grille, and a plurality of rectangular grooves are provided on the steel grille. The locking portion 12 is located in the rectangular groove, and the secondary lining steel bars are fixed to the steel grille through the locking portion 12, and the steel grille is fixed to the tunnel top wall, so that the secondary lining steel bars are fixed to the tunnel, and the secondary lining steel bars and the steel grille and the tunnel top wall are all detachable, and the detachment method can be a snap-fit ​​or buckle-fit connection, so as to achieve detachability.

[0041] In order to ensure good stability when the second lining steel bars are locked with the support part 11, and to prevent loosening in the humid environment of the tunnel, in one embodiment, the locking part 12 includes a vertical rod and a plurality of movable rods, one end of the two movable rods are respectively hinged to the side walls of the rectangular groove, the other ends of the plurality of movable rods are mounted on the same vertical rod through a sliding sleeve, and the other ends of the plurality of movable rods are hinged to the vertical rod, the sliding sleeve is slidably connected to the vertical rod, and the vertical rod is slidably connected to the top wall of the rectangular groove. When the second lining steel bars fall downward as a whole, the vertical rod and the plurality of movable rods are driven to move downward at the same time. At this time, the angle between the plurality of movable rods increases, and the angle between the plurality of movable rods cannot be increased under the squeezing of the rectangular groove, thereby limiting the increase in the angle between the plurality of movable rods, thereby preventing the second lining steel bars from falling downward as a whole.

[0042] Furthermore, when the second lining steel bars in the tunnel have a tendency to fall as a whole, if it is desired to use a plurality of movable rods to prevent the further expansion of the tendency of the second lining steel bars to fall as a whole, it is necessary to further design the structure of the movable rods. In this regard, in one embodiment, the angles between the plurality of movable rods and the side walls of the rectangular groove near the top of the tunnel are acute angles. By designing the angles between the plurality of movable rods and the side walls of the rectangular groove near the top of the tunnel to be acute angles, such as Figure 2 shown.

[0043] Since it is aimed at the second lining steel bars of extra-large span flat tunnels, in this environment, more second lining steel bars are needed. Once the support points of the second lining steel bars are subjected to uneven force, the force will gradually accumulate, resulting in overall uneven force. Therefore, in this case, the design of the support points of the second lining steel bars needs to take into account factors such as whether the force on each support point is uniform and whether the distance between adjacent support points is reasonable. In this regard, in one embodiment, the vertical rod is located at the center of the rectangular groove, and the number of movable rods on the same vertical rod is greater than or equal to four. The rectangular grooves on the steel grating here are of the same size. When in use, the vertical rod is set in the center of the rectangular groove, so as to facilitate the determination of the distance between adjacent support points. In addition, the vertical rod is located at the center of the rectangular groove to ensure that the force on each support point in each rectangular groove is uniform.

[0044] In addition, it is also necessary to note that in the extra-large span flat tunnel 2, a large amount of second lining steel bars are required, so a large amount of straight second lining steel bars and curved second lining steel bars are also required. If the connection between the straight second lining steel bars and the curved second lining steel bars is only connected by welding, in the case of humidity in the tunnel, cracks will also appear at the welding points. Once a crack appears at a certain point, the connection between the straight second lining steel bars and the curved second lining steel bars will be unstable, which will affect the remaining connections near the cracks and finally lead to instability. In order to solve this problem, in one embodiment, the connection between the straight second lining steel bars and the curved second lining steel bars is connected by a gripping mechanism 3, and the gripping mechanism 3 includes a movable portion 31, a four-claw gripping portion 32 and a guide The movable part 31 is slidably mounted on the guide part 33, and the four claws of the four-claw grasping part 32 are evenly hinged on the guide part 33. The four claw side walls of the four-claw grasping part 32 are connected to the movable part 31 through a connecting rod 34. The two ends of the connecting rod 34 are respectively hinged to the four claw side walls of the four-claw grasping part 32 and the movable part 31. The guide part 33 drives the slider to slide along the guide rod of the guide part 33. The movable part 31 drives the connecting rod 34 to slide along the four claw side walls of the four-claw grasping part 32, so that the other ends of the four claws of the four-claw grasping part 32 are clamped on the connection between the straight second lining steel bar and the arc second lining steel bar. Here, the straight second lining steel bar is clamped by designing the four-claw grasping part 32. The connection between the straight second lining steel bar and the curved second lining steel bar is limited and fixed, which can avoid the movement of the connection between the straight second lining steel bar and the curved second lining steel bar in the four directions of front, back, left and right. At the same time, due to the large number of straight second lining steel bars and curved second lining steel bars, the overall weight formed is also heavy, so the weight will be pressed on the four-claw grasping part 32, and the four-claw grasping part 32 can also be restricted from moving up and down, which not only solves the problem of cracks in the weld under humid conditions in the tunnel, but also causes cracks in the weld. Once a crack appears in a certain place, the connection between the straight second lining steel bar and the curved second lining steel bar will be unstable, which will affect the other connections near the crack, and finally cause instability. It can also make the operation convenient when connecting the straight second lining steel bar and the curved second lining steel bar. Compared with the welding method, it is easier to operate and can save time. The guide part 33 here is a guide rod, and the movable part 31 is a slider. However, the guide rod and the slider are movably connected, and the slider can slide upward along the guide rod. The slider slides upward along the guide rod to drive the four claws of the four-claw grasping part 32 away from each other. When the slider slides downward along the guide rod, the four claws of the four-claw grasping part 32 are driven to move closer to each other. The advantage of this design is that when the second lining steel bar has a tendency to fall as a whole, the slider will have a tendency to slide downward, which will make the four claws of the four-claw grasping part 32 closer to each other, and the fixing effect will tend to be better. This design further avoids the risk of the second lining steel bar falling as a whole. Figure 4As shown, in addition, the top end of the guide rod needs to be fixedly connected to the vertical rod, and a plurality of first sockets are provided on the guide rod, and a second socket is also provided on the slider, and the second socket is connected with a pin inside and outside the second socket, and the pin passes through one of the first sockets and the second socket to limit the position between the slider and the guide rod. In order to avoid blocking the slider and the guide rod structure, it is not drawn in the figure.

[0045] One thing that needs to be explained is that Figure 2 It can be seen that the locking portion 12 and the gripping mechanism 3 are described in the same figure. Restrictions are required here, that is, the gripping mechanism 3 is installed first, and then the locking portion 12 is adjusted after the gripping mechanism 3 is stable. The locking portion 12 cooperates with the gripping mechanism 3 to make the overall stability better, and at the same time avoids interference between the gripping mechanism 3 and the locking portion 12 when installing them.

[0046] Considering that the surface of the steel bar has a certain degree of roughness, but since it is aimed at the second lining steel bar of the extra-large span flat tunnel, there needs to be sufficient friction between the four claws of the four-claw grasping part 32 and the surface of the steel bar to ensure that the four-claw grasping part 32 will not loosen when fixing the straight second lining steel bar and the curved second lining steel bar. In this regard, in one embodiment, the four claws of the four-claw grasping part 32 are provided with a plurality of arc-shaped protrusions for increasing the friction between the straight second lining steel bar and the curved second lining steel bar and the four-claw grasping part 32. The ends of the four claws of the four-claw grasping part 32 are pyramid structures. The purpose of the arc-shaped protrusions is to increase the friction and prevent the straight second lining steel bar and the curved second lining steel bar from loosening when the fixing part is used for a long time or is hit by external force. In addition, there are many machines in the construction of the tunnel, which will inevitably touch the second lining steel bar. The ends of the four claws of the four-claw grasping part 32 are pyramid structures to prevent the straight second lining steel bar and the curved second lining steel bar from sliding when touching the second lining steel bar, causing the connection to be out of the limit.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. Accurate installation process for preventing the secondary lining steel bars from falling in extra-large-span flat tunnels, characterized in that: The following steps are involved: S1: Divide the arch top into a number of secondary lining steel bar installation areas along the tunnel from the outside to the inside with a length L as a stepping distance, and set positioning support mechanisms on the plurality of secondary lining steel bar installation areas respectively; S2: Install the second lining steel bar in the outermost second lining steel bar installation area, install the first arc-shaped second lining steel bar along the outermost and innermost arc-shaped edges of the second lining steel bar installation area respectively, and then install the first straight second lining steel bar along the two straight edges of the second lining steel bar installation area respectively, connect the two first straight second lining steel bars and the two first arc-shaped second lining steel bars into one, and finally connect the first straight second lining steel bar and the first arc-shaped second lining steel bar to the positioning support mechanism; S3: Then, two second arc-shaped second lining steel bars are respectively installed outwardly along the innermost first arc-shaped second lining steel bar and inwardly along the outermost first arc-shaped second lining steel bar with a distance of S, and then a second straight second lining steel bar is respectively installed along both ends of the two second arc-shaped second lining steel bars with a distance of H higher than the first straight second lining steel bar in the vertical direction, and the second straight second lining steel bar is connected with the first arc-shaped second lining steel bar and the second arc-shaped second lining steel bar as a whole, and then the second straight second lining steel bar and the second arc-shaped second lining steel bar are connected with the preset positioning support mechanism, and in this way, two third arc-shaped second lining steel bars and two third straight second lining steel bars, two fourth arc-shaped second lining steel bars and two fourth straight second lining steel bars ... two Nth arc-shaped second lining steel bars and two Nth straight second lining steel bars are continuously installed, and finally an N+1th arc-shaped second lining steel bar and an N+1th straight second lining steel bar are installed on the top of the second lining steel bar installation area, so that the second lining steel bars in the outermost second lining steel bar installation area are evenly stressed during installation; S4: Repeat S2 and S3 to install the secondary lining steel bars in the remaining secondary lining steel bar installation areas.

2. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 1 is characterized in that: The number of all the straight secondary lining steel bars and the arc-shaped secondary lining steel bars in S4 is the same.

3. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 1 is characterized in that: The positioning support mechanism used in S2 and S3 is the same, and the positioning support mechanism includes a support part and a locking part. The support part is connected to the top wall of the tunnel vault through a limiter, and the second lining steel bar is locked with the support part through the locking part.

4. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 3 is characterized in that: The supporting part is a steel grille, a plurality of rectangular grooves are arranged on the steel grille, and the locking part is located in the rectangular grooves.

5. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 4 is characterized in that: The locking portion includes a vertical rod and a plurality of movable rods, one end of the plurality of movable rods are respectively hinged to the side walls of the rectangular groove, the other ends of the plurality of movable rods are sleeved on the same vertical rod through a sliding sleeve, and the other ends of the plurality of movable rods are hinged to the side walls of the sliding sleeve, the sliding sleeve is slidably connected to the vertical rod, and the vertical rod is slidably connected to the top wall of the rectangular groove.

6. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 5 is characterized in that: The included angle between the two movable rods and the side wall of the rectangular groove close to the tunnel top is an acute angle.

7. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 5 is characterized in that: The vertical rod is located at the center of the rectangular groove, and the number of movable rods on the same vertical rod is greater than or equal to four.

8. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 4 is characterized in that: The connection between the straight second lining steel bars and the arc-shaped second lining steel bars is connected by a grabbing mechanism, which includes a movable part, a four-claw grabbing part and a guide part connected to the steel grating, the movable part is a slider, one end of the four claws of the four-claw grabbing part is evenly hinged on the guide part, the movable part is slidably mounted on the guide part, the four claw side walls of the four-claw grabbing part are connected to the movable part by a connecting rod, the two ends of the connecting rod are respectively hinged to the four claw side walls of the four-claw grabbing part and the movable part, the guide part drives the slider to slide along the guide rod of the guide part, and the movable part drives the connecting rod to slide along the four claw side walls of the four-claw grabbing part, so that the other ends of the four claws of the four-claw grabbing part clamp the connection between the straight second lining steel bars and the arc-shaped second lining steel bars.

9. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 8 is characterized in that: The four claws of the four-claw grasping part are provided with a plurality of arc-shaped protrusions for increasing the friction between the straight second lining steel bars and the arc-shaped second lining steel bars and the four-claw grasping part.

10. The accurate installation process for preventing the second lining steel bar from falling off in a super-large-span flat tunnel according to claim 9 is characterized in that: The ends of the four claws of the four-claw grasping part are pyramid structures.

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