Construction technology of large-section primary support arch cover for urban rail

Abstract

The present application relates to a construction process for a large-section primary arch cover of an urban rail, including step S1, advanced support construction; step S2, tunnel excavation; step S3, primary arch cover construction; step S31, spraying a concrete reinforcement layer on the inner wall of the tunnel guide tunnel; step S32, supporting a primary arch cover steel frame after the concrete reinforcement layer solidifies, each primary arch cover steel frame includes a pair of side support sections that abut against the inner wall of the tunnel guide tunnel to support the inner wall of the tunnel guide tunnel and a top support section installed between the two side support sections to support the top inner wall of the tunnel guide tunnel, the top support section includes a top cover support body and a pair of movable connectors slidably connected to the top cover support body, the top cover support body is provided with an adjustment mechanism for adjusting the sliding position of the movable connector, and the movable connector is installed on the top of the side support section. The present application has the effect of improving the installation efficiency of the primary arch frame.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel construction, and in particular to a large-section primary support arch construction process for urban rails, and is suitable for tunnel construction in which the arch passes through rock strata mainly consisting of sandstone and sandy mudstone. Background Art

[0002] With the continuous advancement of urban construction in my country, the demand for urban rail transit is increasing, and the design and construction of subway rail transit is becoming more and more common. In the design and construction of subway projects, the construction and operation of subway stations are usually indispensable. In the design and construction process of subway stations, dark excavation construction is the most common method. In the traditional dark excavation construction process, the arch cover construction method is one of the most commonly used methods in dark excavation construction.

[0003] With respect to the above-mentioned related technologies, the inventors believe that there are the following defects: due to the large size of the tunnel, the initial support arch frame in the arch cover method construction is usually composed of multiple sections, including two side support sections distributed on both sides of the tunnel to support the inner wall of the tunnel and a top support section to support the tunnel arch cover. In the arch cover method construction, the side support section is supported first and then the top support section. Due to errors in the construction process, the top support section and the side support section cannot be adapted. When the top support section is too long, it needs to be cut. When the top support section is too short, it is necessary to weld a support compensation section to supplement and reinforce the gap between the top cover support section and the side support section. This is very inconvenient and reduces the installation efficiency of the initial support arch frame, thereby extending the construction period of the initial support arch frame. Therefore, further improvement is needed. Summary of the invention

[0004] In order to improve the installation efficiency of the primary support arch frame, the present application provides a construction process for large-section primary support arch cover of urban rail.

[0005] The urban rail large-section primary support arch construction process provided in this application adopts the following technical solution:

[0006] The construction process of the large-section primary support arch cover of urban rail includes the following steps:

[0007] Step S1, advanced support construction;

[0008] Step S2, tunnel pilot hole excavation;

[0009] Step S3, initial support arch cover construction; the steps include: step S31, spraying a concrete reinforcement layer on the inner wall of the tunnel guide hole, step S32, supporting the initial support arch cover steel frame after the concrete reinforcement layer solidifies, the initial support arch cover steel frame is provided with multiple frames and distributed along the longitudinal direction of the tunnel, each initial support arch cover steel frame includes a pair of side support sections that are abutted against the inner wall of the tunnel guide hole to support the inner wall of the tunnel guide hole and a top support section installed between the two side support sections to support the top inner wall of the tunnel guide hole The support section, the top support section includes a top cover support body and a pair of movable connecting bodies slidably connected to the top cover support body, the top cover support body is provided with an adjustment mechanism for adjusting the sliding position of the movable connecting body, the movable connecting body is installed on the top of the side support section, in step S32, the side support section is locked to the inner wall of the tunnel guide hole by the locking foot anchor rod, and then the top support body is erected, and the sliding amount of the movable connecting body is controlled by the adjustment mechanism, so that the top support body is adapted to be installed on the top of the side support plate.

[0010] By adopting the above technical scheme, when the initial support arch cover construction is carried out on the inner wall of the tunnel guide, the side support sections are supported first, and then the top support sections are supported. During the construction of the top support sections, the sliding movement of the movable connector is adjusted by the adjustment mechanism to be retracted into the top cover support body, so that the length of the top support section is less than the spacing between the two side support sections. When the top cover support body is located above the side support section, the sliding movement of the two movable connectors is adjusted by the adjustment mechanism to extend out of the top cover support body, and then the movable connector is installed on the side support section. In addition, after the movable connector is installed on the side support section, the staff can adjust the sliding movement of the two movable connectors to extend out of the top cover support body again by the adjustment mechanism according to the construction situation, so that the top support section is lifted and pressed against the top inner wall of the tunnel guide, thereby improving the construction flexibility and the efficiency of the initial support arch cover construction.

[0011] Preferably, the top cover support body is provided with a first storage cavity along its length direction, and the end of the top cover support body is open, and the movable connecting body is slidably connected to the first storage cavity, and the adjustment mechanism includes an adjustment shaft rotatably connected to the first storage cavity and located between the two movable connecting bodies, an adjustment gear built into the first storage cavity and coaxially fixedly connected to the adjustment shaft, a first rack fixedly connected to one of the movable connecting bodies, and a second rack fixedly connected to the other movable connecting body, the first rack and the second rack are both meshed with the adjustment gear, the first rack and the second rack are respectively located above and below the adjustment gear, and the tooth surfaces of the first rack and the second rack are arranged opposite to each other. In step S32, the adjustment shaft is driven to rotate the adjustment gear, thereby driving the first rack and the second rack meshed with the adjustment gear to slide in a direction close to or away from each other, thereby adjusting the telescopic sliding amount of the movable connecting body so that the top support section is adapted to be installed on the side support section.

[0012] By adopting the above technical solution, the top cover support body is provided with a first storage cavity to realize the sliding assembly of the top cover support body and the movable connection body. When the sliding and telescopic amount of the movable connection body needs to be adjusted, the adjusting shaft is rotated to drive the adjusting gear to rotate, thereby driving the first rack and the second rack engaged with the adjusting gear to slide towards each other or away from each other, thereby adjusting the telescopic sliding amount of the movable connection body so that the top support section is adapted to be installed on the side support section.

[0013] Preferably, the adjusting shaft includes a rotating shaft rotatably connected to the inner wall of the first storage chamber and a movable shaft coaxially and circumferentially linked to the rotating shaft, the movable shaft is axially slidably connected to the rotating shaft, the movable shaft has a stop portion with a polygonal cross-section, the outer wall of the top cover support body is fixedly connected with a stop sleeve sleeved on the movable shaft, the stop sleeve has a stop groove adapted to the stop portion, the adjusting mechanism also includes a handwheel fixedly connected to the movable shaft and located outside the stop sleeve, in step S32, before rotating the adjusting shaft, it is necessary to first apply a force to the handwheel to drive the movable shaft to slide, so that the stop portion on the movable shaft disengages from the stop groove of the stop sleeve, and then apply a torque to the handwheel to drive the movable shaft to rotate, thereby driving the rotating shaft to rotate.

[0014] By adopting the above technical scheme, by setting the stop part and the stop sleeve, the hand wheel has a rotation limiting effect in the normal state. During the construction of the top support section, a force is first applied to the hand wheel to drive the movable shaft to slide, so that the stop part on the movable shaft is disengaged from the stop groove of the stop sleeve, and then a torque is applied to the hand wheel to drive the movable shaft to rotate, and then drive the rotating shaft to rotate. After the adjustment is completed, a force is applied to the hand wheel to make the movable shaft slide and reset, so that the stop part is embedded in the stop groove of the stop sleeve, and the rotation of the hand wheel is restricted, which effectively reduces the possibility of slipping of the movable connection body due to its own weight, improves construction safety and operational convenience, and when the top cover support body is located above the side support section, the operation is repeated to adjust the sliding position of the movable connection body, so that the top support section is adapted to be installed on the side support section.

[0015] Preferably, a spring is provided between the handwheel and the stop sleeve to force the movable shaft to slide toward the rotating shaft so that the stop portion is embedded in the stop groove. The spring sleeve is arranged on the movable shaft, one end of the spring is fixedly connected to the stop sleeve, and the other end of the spring is rotatably connected to the stop portion. In step S32, before rotating the adjusting shaft, it is necessary to first apply a force to the handwheel to drive the movable shaft to slide, so that the stop portion on the movable shaft is disengaged from the stop groove of the stop sleeve, and the spring undergoes elastic deformation and has elastic potential energy. Subsequently, a torque is applied to the handwheel to drive the movable shaft to rotate, and then the rotating shaft is driven to rotate. After the force applied to the handwheel is removed, the spring forces the movable shaft to slide and reset so that the stop portion is embedded in the stop groove.

[0016] By adopting the above technical solution, when it is necessary to turn the handwheel, a force is applied to the handwheel in the direction away from the stop sleeve, thereby driving the movable shaft to slide in the direction away from the rotating shaft, thereby pulling the stop portion of the movable shaft out of the stop groove of the stop sleeve, and then the handwheel is turned to drive the movable shaft to rotate, and the corresponding rotating shaft is driven to rotate and then drives the adjusting gear to rotate. After the adjustment is completed, after the force applied to the handwheel is removed, the spring forces the movable shaft to slide back to its original position so that the stop portion is embedded in the stop groove.

[0017] Preferably, the movable connecting body is provided with a second storage cavity, and the movable connecting body is opened at one end close to the adjusting gear, and the second storage cavities of the two movable connecting bodies are respectively slidably connected with the first reinforcement body and the second reinforcement body, the first reinforcement body and the first rack are arranged on the same movable connecting body, the second reinforcement body and the second rack are arranged on the same movable connecting body, the first reinforcement body and the second rack are fixedly connected, the second reinforcement body and the first rack are fixedly connected, and the first reinforcement body and the second reinforcement body are both located between the first rack and the second rack.

[0018] By adopting the above technical solution, a second receiving cavity is provided to realize the sliding and retracting of the first reinforcement body and the second reinforcement body on the movable connecting body. When the first rack and the second rack slide away from each other, the first reinforcement body and the second reinforcement body are driven to slide toward each other and extend into the first receiving cavity, thereby improving the supporting bearing capacity of the top cover support body in the middle area of ​​the first receiving cavity and reducing the possibility of fracture in the middle part of the top cover support body.

[0019] Preferably, the top cover support body is provided with a grouting hole connected to the first receiving cavity, and the first reinforcement body and the second reinforcement body both have a slurry flow channel, and the slurry flow channel is connected to the first receiving cavity and the second receiving cavity. In step S32, when the first rack and the second rack slide away from each other, the first reinforcement body and the second reinforcement body are driven to slide toward each other and extend into the first receiving cavity, and then concrete mortar is poured into the first receiving cavity through the grouting hole, and the concrete mortar flows into the second receiving cavity through the slurry flow channel.

[0020] By adopting the above technical solution, concrete mortar is poured into the first receiving cavity through the grouting hole, and the concrete mortar flows into the second receiving cavity through the slurry flow channel, thereby further improving the bearing capacity of the movable connecting body and the top cover supporting body.

[0021] Preferably, the end face of the side support section is fixedly connected with a first connecting plate, the end of the movable connecting member is hinged with a second connecting plate, and the first connecting plate and the second connecting plate are connected by bolts. In step S32, after the adjustment mechanism controls the slippage of the movable connecting body, the inclination angle of the second connecting plate is adjusted so that the second connecting plate and the first connecting plate are in a parallel abutment state, and then the first connecting plate and the second connecting plate are locked with bolts.

[0022] By adopting the above technical solution, after the adjustment mechanism controls the slippage of the movable connecting body, the angle of the second connecting plate can be flexibly adjusted, so that the second connecting plate and the first connecting plate are in a parallel abutment state, which is convenient for the installation of the second connecting plate and the first connecting plate.

[0023] Preferably, in step S32, temporary steel supports are provided at the arch feet of the supporting arch cover steel frame.

[0024] Preferably, the temporary steel support includes a supporting base plate detachably connected to the rock mass at the bottom of the tunnel guide hole, a reinforcing oblique arm hinged to the supporting base plate, and a fixing plate hinged to the other end of the reinforcing oblique arm, and the fixing plate is detachably connected to the side support section.

[0025] By adopting the above technical scheme, temporary steel supports are set at the lower part of the arch foot of the primary arch cover steel frame, and prestress is applied, so that the rock mass at the large arch foot of the primary arch cover steel frame is in a constrained state, thereby strengthening the bearing capacity of the rock mass at the large arch foot and ensuring the stability of the rock mass at the arch foot.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] 1. When the inner wall of the tunnel pilot hole is initially supported and the arch cover is constructed, the side support sections are first supported, and then the top support sections are supported. During the construction of the top support sections, the sliding movement of the movable connecting body is adjusted by the adjusting mechanism to be retracted into the top cover supporting body, so that the length of the top support section is less than the spacing between the two side support sections. When the top cover supporting body is located above the side support sections, the sliding movement of the two movable connecting bodies is adjusted by the adjusting mechanism to extend out of the top cover supporting body, and then the movable connecting body is installed on the side support sections. In addition, after the movable connecting body is installed on the side support section, the staff can adjust the sliding movement of the two movable connecting bodies to extend out of the top cover supporting body again by the adjusting mechanism according to the construction situation, so that the top support section is lifted and pressed against the top inner wall of the tunnel pilot hole, thereby improving the construction flexibility and the efficiency of the initial support and arch cover construction;

[0028] 2. A second receiving cavity is provided to enable the first reinforcement body and the second reinforcement body to slide and retract on the movable connecting body. When the first rack and the second rack slide away from each other, the first reinforcement body and the second reinforcement body are driven to slide toward each other and extend into the first receiving cavity, thereby improving the supporting bearing capacity of the top cover support body in the middle area of ​​the first receiving cavity and reducing the possibility of fracture in the middle part of the top cover support body. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an overall schematic diagram of the construction process of large-section primary support arch cover of urban rail.

[0030] Figure 2 It is a structural diagram of the primary support arch cover steel frame.

[0031] Figure 3 It is a structural diagram of the top support section.

[0032] Figure 4 yes Figure 3 A local enlarged schematic diagram at point A.

[0033] Figure 5 It is a schematic diagram of the structure of the adjusting shaft.

[0034] Figure 6 yes Figure 5 A partial enlarged schematic diagram at point B.

[0035] Explanation of the accompanying drawings: 1. Side support section; 11. Arch foot seat; 12. Locking foot anchor rod; 13. First connecting plate; 2. Top support section; 21. Top cover support body; 22. Movable connecting body; 23. First receiving cavity; 24. Second connecting plate; 25. Second receiving cavity; 26. First reinforcement body; 27. Second reinforcement body; 28. Slurry flow channel; 29. ​​Grouting hole; 20. Stop sleeve; 201. Stop groove; 202. Spring; 3. Temporary steel support; 31. Support bottom plate; 32. Reinforced oblique arm; 33. Fixed plate; 4. Adjustment mechanism; 41. Adjustment shaft; 411. Rotation shaft; 412. Movable shaft; 413. Stop part; 42. Adjustment gear; 43. First rack; 44. Second rack; 45. Handwheel; 46. First connecting block; 47. Second connecting block; 5. Steel mesh; 6. Radial anchor rod. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1-6 This application is described in further detail.

[0037] The present application embodiment discloses a construction process for a large-section primary support arch cover of an urban rail, comprising the following steps:

[0038] Step S1, advanced support construction.

[0039] Step S2: excavation of the tunnel pilot tunnel, which is carried out by combining manual excavation with mechanical excavation.

[0040] Step S3, initial support arch cover construction, includes the following steps: Step S31, initial spraying of a concrete reinforcement layer on the inner wall of the tunnel pilot hole.

[0041] Step S32: After the concrete reinforcement layer solidifies, the initial arch cover steel frame is supported. Figure 1 , Figure 2The primary support arch cover steel frame is provided with multiple frames and is evenly distributed along the longitudinal direction of the tunnel. Each primary support arch cover steel frame includes a pair of side support sections 1 abutting against the inner wall of the tunnel guide hole to support the inner wall of the tunnel guide hole and a top support section 2 installed between the two side support sections 1 to support the top inner wall of the tunnel guide hole. The side support section 1 and the top support section 2 are both arranged in arc segments. In this embodiment, the side support section 1 is a solid steel column pile.

[0042] The lower part of the side support section 1 is fixedly connected with an arch foot seat 11, and the arch foot seat 11 is fixedly penetrated with a locking foot anchor rod 12 inserted into the rock formation. The upper end face of the side support section 1 is fixedly connected with a first connecting plate 13, and the first connecting plate 13 is provided with a threaded hole. The side support section 1 is provided with a temporary steel support 3, which includes a support base plate 31 detachably connected to the rock mass at the bottom of the tunnel guide hole, a reinforcing inclined arm 32 hinged to the support base plate 31, and a fixing plate 33 hinged to the other end of the reinforcing inclined arm 32, and the fixing plate 33 is detachably connected to the middle part of the side support section 1 by bolts.

[0043] Reference Figure 3 , Figure 4 The top support section 2 includes a top cover support body 21 and a pair of movable connecting bodies 22 slidably connected to the top cover support body 21. The top cover support body 21 is provided with a first receiving cavity 23 along its arc length direction. The end of the top cover support body 21 is open, and the movable connecting body 22 is slidably connected to the first receiving cavity 23. The top cover support body 21 is provided with an adjustment mechanism 4 for adjusting the sliding position of the movable connecting body 22. The adjustment mechanism 4 includes an adjustment shaft 41, an adjustment gear 42, a first rack 43, a second rack 44 and a hand wheel 45. The adjustment shaft 41 is rotatably connected to the top cover support body 21 and is located between the two movable connecting bodies 22. The axial direction of the adjustment shaft 41 is parallel to the depth direction of the tunnel guide hole. The adjustment gear 42 is built into the first receiving cavity 23, and the adjustment gear 42 is coaxially fixedly sleeved on the adjustment shaft 41. The first rack 43 is fixedly connected to one of the movable connecting bodies 22, and the second rack 44 is fixedly connected to the other movable connecting body 22. The first rack 43 and the second rack 44 are both meshed with the adjusting gear 42. The first rack 43 and the second rack 44 are respectively located above and below the adjusting gear 42, and the tooth surfaces of the first rack 43 and the second rack 44 are arranged opposite to each other.

[0044] The movable connecting body 22 is provided with a second receiving chamber 25, and one end of the movable connecting body 22 near the adjusting gear 42 is open. The second receiving chambers 25 of the two movable connecting bodies 22 are respectively connected with the first reinforcing body 26 and the second reinforcing body 27 in sliding manner. The first reinforcing body 26 and the first rack 43 are provided on the same movable connecting body 22, and the second reinforcing body 27 and the second rack 44 are provided on the same movable connecting body 22. The first reinforcing body 26 and the second rack 44 are fixedly connected by the first connecting block 46, and the second reinforcing body 27 and the first rack 43 are fixedly connected by the second connecting block 47. The first reinforcing body 26 and the second reinforcing body 27 are both located between the first rack 43 and the second rack 44. The top cover support body 21 is provided with a grouting hole 29 connected to the first receiving chamber 23, and the first reinforcing body 26 and the second reinforcing body 27 both have a slurry flow channel 28, and the slurry flow channel 28 is connected to the first receiving chamber 23 and the second receiving chamber 25. A second connecting plate 24 is hingedly connected to the closed end surface of the movable connecting piece, and the second connecting plate 24 is provided with a strip-shaped mounting hole.

[0045] Reference Figure 5 , Figure 6 The adjusting shaft 41 includes a rotating shaft 411 rotatably connected to the inner wall of the first receiving chamber 23 and a movable shaft 412 coaxially and circumferentially linked to the rotating shaft 411. One end of the rotating shaft 411 is built into the first receiving chamber 23 and the other end is located outside the top cover support body 21. The adjusting gear 42 is coaxially and fixedly connected to the rotating shaft 411. The movable shaft 412 is located outside the top cover support body 21, and the movable shaft 412 is axially slidably connected to the rotating shaft 411. The movable shaft 412 has a stopper 413 with a polygonal cross section. The outer side wall of the top cover support body 21 is fixedly connected to a stopper sleeve 20 coaxially sleeved on the rotating shaft 411 and the movable shaft 412. The end of the stopper sleeve 20 away from the top cover support body 21 is provided with a stopper groove 201 adapted to the stopper 413. The hand wheel 45 is coaxially and fixedly connected to the movable shaft 412, and the hand wheel 45 is located outside the stopper sleeve 20. A spring 202 is provided between the handwheel 45 and the stop sleeve 20 to force the movable shaft 412 to slide toward the rotating shaft 411 so that the stop portion 413 is embedded in the stop groove 201. The spring 202 is built into the stop sleeve 20. The spring 202 is sleeved on the rotating shaft 411 and the movable shaft 412. One end of the spring 202 is fixedly connected to the stop sleeve 20, and the other end of the spring 202 is rotatably connected to the stop portion 413.

[0046] In step S32, first support the side support sections 1 on both sides of the tunnel, lock the side support sections 1 to the inner wall of the tunnel guide hole by the locking foot anchor rods 12, and set up temporary steel supports 3. Then set up the top support body. During the setting up of the top support body, first apply force to the hand wheel 45 to drive the movable shaft 412 to slide, so that the stopper 413 on the movable shaft 412 is separated from the stop groove 201 of the stop sleeve 20, and then apply torque to the hand wheel 45 to drive the movable shaft 412 to rotate, and then drive the rotating shaft 411 to rotate, so that the first rack 43 and the second rack 44 slide in a direction close to each other, and the sliding of the movable connecting body 22 is retracted in the top cover support body 21, so that the arc length of the top support section 2 is less than the distance between the upper parts of the two side support sections 1. After the adjustment is completed, apply force to the hand wheel 45 to make the movable shaft 412 slides and resets, so that the stopper 413 is embedded in the stopper groove 201 of the stopper sleeve 20, and the hand wheel 45 is restricted from rotating, which effectively reduces the possibility of the movable connecting body 22 sliding due to its own weight, improves the construction safety and operation convenience, and when the top cover support body 21 is located above the side support section 1, the rotation adjustment shaft 41 is repeatedly operated to make the first rack 43 and the second rack 44 slide in the direction away from each other, adjust the inclination angle of the second connecting plate 24, so that the second connecting plate 24 and the first connecting plate 13 are in a parallel abutment state, and then the first connecting plate 13 and the second connecting plate 24 are locked with bolts. When the first rack 43 and the second rack 44 slide in the direction away from each other, the first reinforcing body 26 and the second reinforcing body 27 are driven to slide in the direction of approaching each other and extend into the first receiving chamber 23, and then the first receiving chamber 23 is poured with concrete mortar through the grouting hole 29, and the concrete mortar flows into the second receiving chamber 25 through the grouting channel 28.

[0047] Step S33, a steel plate or a steel mesh 5 is fixedly connected between two adjacent primary supporting arch cover steel frames. In this embodiment, the steel mesh 5 is fixedly connected between two adjacent primary supporting arch cover steel frames, and a radial anchor rod 6 is fixed on the steel mesh 5 for being inserted into the inner wall of the tunnel guide hole between the two adjacent primary supporting arch cover steel frames.

[0048] Step S34, spraying concrete again to form an initial support structure composed of an initial support arch cover steel frame + radial anchor rods 6 + sprayed concrete.

[0049] Step S4, after the sprayed concrete solidifies, the temporary steel support 3 is removed.

[0050] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. The construction process of large-section primary support arch cover of urban rail is characterized by: The following steps are involved: Step S1, advanced support construction; Step S2, tunnel pilot hole excavation; Step S3, initial support arch cover construction; The method comprises the following steps: step S31, spraying a concrete reinforcement layer on the inner wall of the tunnel guide hole; step S32, supporting a primary arch cover steel frame after the concrete reinforcement layer solidifies; the primary arch cover steel frame is provided with a plurality of frames and distributed along the longitudinal direction of the tunnel; each primary arch cover steel frame comprises a pair of side support sections (1) abutting against the inner wall of the tunnel guide hole to support the inner wall of the tunnel guide hole and a top support section (2) installed between the two side support sections (1) to support the top inner wall of the tunnel guide hole; the top support section (2) comprises a top cover support body (21) and a pair of slidingly connected to the top cover support body (21); 1), the top cover support body (21) is provided with an adjustment mechanism (4) for adjusting the sliding position of the movable connection body (22), the movable connection body (22) is installed on the top of the side support segment (1), in step S32, the side support segment (1) is locked to the inner wall of the tunnel guide hole by the locking foot anchor rod (12), and then the top support body is erected, and the sliding amount of the movable connection body (22) is controlled by the adjustment mechanism (4) so ​​that the top support body is adapted to be installed on the top of the side support plate; the top cover support body (21) is provided with a first storage cavity (23) along its length direction, and the top cover support The end of the guard (21) is open, the movable connecting body (22) is slidably connected to the first receiving cavity (23), the adjustment mechanism (4) comprises an adjustment shaft (41) rotatably connected to the first receiving cavity (23) and located between the two movable connecting bodies (22), an adjustment gear (42) built into the first receiving cavity (23) and coaxially fixedly connected to the adjustment shaft (41), a first rack (43) fixedly connected to one of the movable connecting bodies (22) and a second rack (44) fixedly connected to the other movable connecting body (22), the first rack (43) and the second rack (44) being arranged to rotate relative to each other. 4) are both meshed with the adjusting gear (42), the first rack (43) and the second rack (44) are respectively located above and below the adjusting gear (42), and the tooth surfaces of the first rack (43) and the second rack (44) are arranged opposite to each other. In step S32, the adjusting gear (42) is driven to rotate by rotating the adjusting shaft (41), thereby driving the first rack (43) and the second rack (44) meshed with the adjusting gear (42) to slide in a direction closer to or away from each other, thereby adjusting the telescopic sliding amount of the movable connecting body (22) so that the top support section (2) is adapted to be installed on the side support section (1).

2. The construction process for large-section primary support arch cover of urban rail according to claim 1, characterized in that: The adjusting shaft (41) comprises a rotating shaft (411) rotatably connected to the inner wall of the first receiving chamber (23) and a movable shaft (412) coaxially and circumferentially linked to the rotating shaft (411); the movable shaft (412) is axially slidably connected to the rotating shaft (411); the movable shaft (412) has a stopper (413) with a polygonal cross section; the outer side wall of the top cover support body (21) is fixedly connected to a stopper sleeve (20) sleeved on the movable shaft (412); the stopper sleeve (20) has a stopper sleeve adapted to fit the stopper sleeve (413). The adjusting mechanism (4) further comprises a hand wheel (45) fixedly connected to the movable shaft (412) and located outside the stop sleeve (20). In step S32, before rotating the adjusting shaft (41), it is necessary to first apply a force to the hand wheel (45) to drive the movable shaft (412) to slide, so that the stop portion (413) on the movable shaft (412) is disengaged from the stop groove (201) of the stop sleeve (20), and then apply a torque to the hand wheel (45) to drive the movable shaft (412) to rotate, thereby driving the rotating shaft (411) to rotate.

3. The construction process for large-section primary support arch cover of urban rail according to claim 2, characterized in that: A spring (202) is provided between the hand wheel (45) and the stop sleeve (20) to force the movable shaft (412) to slide toward the rotating shaft (411) so that the stop portion (413) is embedded in the stop groove (201). The spring (202) is sleeved on the movable shaft (412). One end of the spring (202) is fixedly connected to the stop sleeve (20), and the other end of the spring (202) is rotatably connected to the stop portion (413). In step S32, before rotating the adjusting shaft (41), it is necessary to first apply an action to the hand wheel (45). The movable shaft (412) is driven to slide by force, so that the stop portion (413) on the movable shaft (412) is disengaged from the stop groove (201) of the stop sleeve (20), and the spring (202) undergoes elastic deformation and has elastic potential energy. Subsequently, a torque is applied to the hand wheel (45) to drive the movable shaft (412) to rotate, thereby driving the rotating shaft (411) to rotate. After the force applied to the hand wheel (45) is removed, the spring (202) forces the movable shaft (412) to slide and reset, so that the stop portion (413) is embedded in the stop groove (201).

4. The construction process for large-section primary support arch cover of urban rail according to claim 1, characterized in that: The movable connecting body (22) is provided with a second receiving chamber (25), and one end of the movable connecting body (22) close to the adjusting gear (42) is open. The second receiving chambers (25) of the two movable connecting bodies (22) are respectively slidably connected with a first reinforcing body (26) and a second reinforcing body (27). The first reinforcing body (26) and the first rack (43) are arranged on the same movable connecting body (22), and the second reinforcing body (27) and the second rack (44) are arranged on the same movable connecting body (22). The first reinforcing body (26) and the second rack (44) are fixedly connected, and the second reinforcing body (27) and the first rack (43) are fixedly connected. The first reinforcing body (26) and the second reinforcing body (27) are both located between the first rack (43) and the second rack (44).

5. The construction process for large-section primary support arch cover of urban rail according to claim 4, characterized in that: The top cover support body (21) is provided with a grouting hole (29) connected to the first receiving chamber (23); the first reinforcement body (26) and the second reinforcement body (27) both have a slurry flow channel (28); the slurry flow channel (28) is connected to the first receiving chamber (23) and the second receiving chamber (25); in step S32, when the first rack (43) and the second rack (44) slide in a direction away from each other, the first reinforcement body (26) and the second reinforcement body (27) are driven to slide in a direction close to each other and extend into the first receiving chamber (23); then, concrete mortar is poured into the first receiving chamber (23) through the grouting hole (29); and the concrete mortar flows into the second receiving chamber (25) through the slurry flow channel (28).

6. The construction process for large-section primary support arch cover of urban rail according to claim 1, characterized in that: The end face of the side support section (1) is fixedly connected to a first connecting plate (13), and the end of the movable connecting body (22) is hinged to a second connecting plate (24). The first connecting plate (13) and the second connecting plate (24) are connected by bolts. In step S32, the adjusting mechanism (4) controls the sliding amount of the movable connecting body (22), and then adjusts the inclination angle of the second connecting plate (24), so that the second connecting plate (24) and the first connecting plate (13) are in a parallel abutment state, and then the first connecting plate (13) and the second connecting plate (24) are locked by bolts.

7. The construction process for large-section primary support arch cover of urban rail according to claim 1, characterized in that: In step S32, temporary steel supports (3) are provided at the arch feet of the supporting arch cover steel frame.

8. The construction process for large-section primary support arch cover of urban rail according to claim 7, characterized in that: The temporary steel support (3) comprises a support base plate (31) detachably connected to the rock mass at the bottom of the tunnel pilot hole, a reinforcing inclined arm (32) hinged to the support base plate (31), and a fixing plate (33) hinged to the other end of the reinforcing inclined arm (32), wherein the fixing plate (33) is detachably connected to the side support section (1).

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