A method for constructing a precast column inspection pit bed

Abstract

The present application relates to the field of track bed construction tooling equipment, and particularly relates to a prefabricated column inspection pit track bed construction method, which comprises the steps of setting a storage rack to vertically support prefabricated columns in a foundation pit and setting a center support to transversely support prefabricated columns in the foundation pit, the bottom of the prefabricated column is provided with reserved steel bars, the foundation pit is embedded with vertical connecting steel bars, the storage rack is removed after the track rack is set, the reserved steel bars are welded with the vertical connecting steel bars after track fine adjustment, and then the step of cast-in-place concrete is performed to realize prefabricated column inspection pit track bed forming. The prefabricated column is in a non-fixed state during track installation and fine adjustment, so that the installation precision of the prefabricated column does not affect the installation precision of the track, and the installation precision of the prefabricated column and the installation precision of the track can be simultaneously satisfied; the prefabricated column fixing and the track bed forming are synchronously performed, the construction efficiency is improved, meanwhile, the storage rack and the center support can be recycled, which is conducive to reducing the construction cost of the inspection pit track bed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of track bed construction equipment, in particular to a prefabricated column inspection pit track bed construction method. BACKGROUND

[0002] The column inspection pit track bed is a maintenance area that must be configured for urban rail transit lines, and the column is usually formed by cast-in-place, the rail is installed on the top of the column, and the rail is longitudinally spliced to form a vehicle track, and a maintenance space is formed below the track to facilitate vehicle maintenance. However, the cast-in-place construction quality is difficult to control, the appearance quality is poor, and secondary decoration is often required, and the maintenance amount is also large in the later period.

[0003] In order to overcome the above-mentioned defects of the cast-in-place column inspection pit track bed, at present, the column inspection pit is replaced by a prefabricated concrete column instead of the original cast-in-place column. The prefabricated column has an attractive appearance and does not require secondary decoration or maintenance in the later period, which can greatly improve the construction efficiency of the inspection pit track bed. During construction, the civil construction unit first constructs the civil foundation of the inspection pit, sets a pre-embedded part in the civil foundation, and then the track unit installs the prefabricated column. The bottom of the prefabricated column is connected with the pre-embedded part, and after the prefabricated column is fixed, the installation and fine adjustment of the top rail are carried out. Therefore, the installation precision of the prefabricated column will directly affect the installation precision of the upper rail. However, the setting position of the pre-embedded part is prone to deviation, and the preparation of the prefabricated column also inevitably has size errors, which can adversely affect the installation precision of the prefabricated column, and further affect the installation precision of the rail. Chinese invention patent CN107268348A provides a subway column inspection pit construction method, which supports the rail by a door-shaped support, and provides a construction process of first installing the rail and then installing the prefabricated column. However, the door-shaped support is set in the inspection pit, which will affect the pouring of concrete in the inspection pit. If it is set outside the inspection pit, additional installation planes are needed, and all door-shaped supports need to be kept at the same installation height, which increases the construction difficulty. At the same time, the weight of a single prefabricated column can reach 500 kg, and the weight of a 25 m rail can reach 20.5 t. Due to the large weight of the prefabricated column, the structural strength requirement of the door-shaped support is also correspondingly increased, which increases the preparation cost of the door-shaped support. The preparation, installation and removal of auxiliary equipment greatly affect the installation efficiency of the prefabricated column and the construction efficiency of the track bed. Moreover, the above two construction methods cannot provide a working platform for the workers, which affects the construction of the corresponding process by the workers and affects the work efficiency.

[0004] Therefore, there is an urgent need for a technical solution to solve the technical problem that the existing prefabricated column inspection pit track bed construction cannot simultaneously consider the rail installation precision, the inspection pit track bed construction efficiency and the cost, because if the prefabricated column is fixed first and then the rail is installed, the rail installation precision will be affected, and if the rail is installed first and then the prefabricated column is installed, the preparation cost of auxiliary equipment will be increased. SUMMARY

[0005] The present application aims at checking the technical problem that the existing prefabricated column inspection pit construction process cannot balance the track installation precision, the inspection pit bed construction efficiency and the cost, and provides a prefabricated column inspection pit bed construction method.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0007] A prefabricated column inspection pit bed construction method, comprising the steps of arranging a storage rack to vertically support the prefabricated column in the foundation pit and arranging a center support to transversely support the prefabricated column in the foundation pit, the bottom of the prefabricated column is provided with a reserved steel bar, the foundation pit is embedded with a vertical connecting steel bar, the storage rack is removed after the track rack is arranged, the reserved steel bar and the vertical connecting steel bar are welded after the track is precisely adjusted, and then the step of pouring cast-in-place concrete is performed to realize the forming of the prefabricated column inspection pit bed.

[0008] The prefabricated column inspection pit bed construction method of the present application realizes the positioning of the prefabricated column through the storage rack and the center support, ensures the installation stability of the prefabricated column in a non-fixed state, performs track installation and precise adjustment before the prefabricated column is fixed, makes the prefabricated column in a non-fixed state during track installation and precise adjustment, avoids the influence of the installation precision of the prefabricated column on the track installation precision, can simultaneously satisfy the installation precision of the prefabricated column and the installation precision of the track, realizes the synchronous fixing of the prefabricated column and the forming of the bed through cast-in-place concrete, improves the construction efficiency, and at the same time, the storage rack and the center support are removed at the appropriate time and can be recycled, which is beneficial to reducing the construction cost of the inspection pit bed.

[0009] As a preferred scheme of the present application, the storage rack comprises two support rods arranged in parallel, each support rod is provided with a top flat surface and a bottom steel foot arranged in line, the two support rods are placed in the foundation pit to form a through area for the reserved steel bar to pass through, the prefabricated column is supported by the top flat surface to form the vertical support. The storage rack is placed in the foundation pit in a placed manner, the position is flexible to adjust, the installation and removal are convenient, the prefabricated column is placed on the top flat surface of the storage rack in a gravity ballast manner to realize the stable vertical support of the prefabricated column.

[0010] As a preferred scheme of the present application, the center support comprises a support frame, a cross brace and a clamping mechanism, the support frame has a width not greater than the transverse design width of the center ditch of the inspection pit, the support frame is fixed to the longitudinal center line of the foundation pit by expansion bolts, the clamping mechanism is sleeved on the prefabricated column and connected with the support frame by the cross brace to form the transverse support. The center support is installed in the position of the center ditch of the inspection pit by bolt fixation, temporarily occupying the construction area of the center ditch of the inspection pit, not only providing stable transverse support for the prefabricated column to prevent the prefabricated column from falling down, but also serving as a formwork fixing support for concrete pouring, and being convenient to install and disassemble, which is conducive to repeated use.

[0011] As a preferred scheme of the present application, the clamping mechanism comprises a clamping part and a connecting part, the clamping part and the connecting part form a frame-shaped structural member adapted to the outer shape of the prefabricated column, the connecting part is fixedly connected with the end of the cross brace, and the clamping part is detachably connected with the connecting part. The clamping part provides circumferential stability for the prefabricated column, and the cross brace is connected with the support frame to further realize stable transverse support for the prefabricated column. Meanwhile, the detachable connection of the clamping part and the connecting part is also conducive to the overall disassembly of the center support, facilitating the repeated use of the center support.

[0012] As a preferred scheme of the present application, the step of providing a working platform by erecting a platform plate on the longitudinally adjacent cross braces is further included. The center support can also serve as the bottom support of the working platform to provide a working area for the workers during the process steps such as concrete pouring and track installation and adjustment, thereby improving the construction efficiency.

[0013] As a preferred scheme of the present application, the reserved steel bars are staggered welded with the vertical connecting steel bars or connected by auxiliary horizontal steel bars. When the reserved steel bars are in contact with the vertical connecting steel bars, the fixation can be realized by welding. When the reserved steel bars have a transverse spacing from the vertical connecting steel bars, the auxiliary horizontal steel bars are used for connection, which reduces the installation precision requirement for the prefabricated column, reduces the difficulty of installation and fixation of the prefabricated column, and is conducive to improving the overall construction efficiency.

[0014] As a preferred scheme of the present application, the step of pouring the cast-in-place concrete comprises fixing a first inner side formwork on the center support and erecting an outer side formwork on the side wall of the foundation pit to form a first pouring space. This reduces the installation difficulty of the first inner side formwork, reduces the formwork erection cost, realizes the dual-effect assistance function of stable installation of the prefabricated column and concrete pouring process.

[0015] As a preferred embodiment of the present invention, the step of casting the concrete includes erecting a second inner formwork above the concrete substrate formed in the first casting space, forming a second casting space between the second inner formwork and the outer formwork. This forms a layered casting process for the inspection tunnel bed. During the casting of the second casting space, the bottom surface of the inspection tunnel bed is flat, the second inner formwork is easy to install, and the precast columns are already fixed by the concrete below, ensuring stable track installation. This avoids the casting of the second casting space affecting the accuracy of the precast columns or tracks, reducing the requirements for casting and helping to lower the overall construction efficiency and cost of the inspection tunnel bed.

[0016] As a preferred embodiment of the present invention, the specific steps include: S1: roughening the bottom wall of the foundation pit; S2: measuring and positioning the center line of the track and the installation position of the column according to the design dimensions of the inspection tunnel bed, and placing the storage rack and installing the central support according to the measurement and positioning results; S3: lifting the precast column with mechanical equipment and placing it on the top surface of the storage rack, and providing lateral support through the central support; S4: forming a working platform by laying wooden planks on adjacent horizontal supports; S5: lifting the steel rail to the top surface of the precast column with mechanical equipment, and connecting and fixing it with fasteners to form a rail panel; S6: lifting the rail panel and removing it from the storage rack. S7: Lay out the support frame and complete the fine-tuning of the track panel; S8: Weld and fix the reserved steel bars and vertical connecting steel bars; S9: Tie and set up the steel cage for the space to be poured; S0: Install the outer formwork and the first inner formwork in the foundation pit to form the first pouring space and pour concrete. The height of the first pouring space is level with the top elevation of the central ditch; S10: Remove the central support and the first inner formwork, and erect the second inner formwork on the top surface of the concrete base formed in S9 to form the second pouring space and pour concrete; S11: After removing the second inner formwork, level the bottom of the central ditch. The above process integrates the advantages of stable installation and fixing of precast columns, high precision of track installation, reduced difficulty and cost of layered concrete pouring, and cost reduction through the reuse of auxiliary tools, achieving low-cost, high-quality, and high-efficiency construction of precast column inspection tunnel beds.

[0017] As a preferred embodiment of the present invention, the concrete pouring includes vibratory pouring to ensure the structural quality of the cast-in-place concrete portion of the tunnel bed is inspected.

[0018] In summary, due to the adoption of the above technical solutions, the beneficial effects of the prefabricated column inspection tunnel bed construction method of the present invention are:

[0019] 1. The precast columns are positioned using storage racks and central supports to ensure installation stability when the precast columns are not fixed.

[0020] 2. By installing and fine-tuning the track before fixing the precast column, the column is in a non-fixed state during the track installation and fine-tuning, which avoids the installation accuracy of the precast column affecting the installation accuracy of the track, and can simultaneously meet the installation accuracy of the precast column and the installation accuracy of the track.

[0021] 3. By using cast-in-place concrete, the fixing of precast columns and the forming of the track bed can be carried out simultaneously, which improves construction efficiency;

[0022] 4. The storage racks and central supports can be dismantled at appropriate times and reused, which helps reduce the construction cost of the inspection tunnel bed. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the prefabricated column inspection tunnel bed after it has been formed in this invention;

[0024] Figure 2 This is a schematic diagram of the storage rack described in the embodiment;

[0025] Figure 3 This is a schematic diagram of the support frame described in the embodiment;

[0026] Figure 4 This is a schematic diagram of the combination of the storage rack and the support frame described in Embodiment 1;

[0027] Figure 5 This is a schematic diagram of the prefabricated column in a non-fixed state in Example 1;

[0028] Figure 6 This is a schematic diagram of the precast column inspection tunnel bed during the pouring of the first pouring space in Example 4;

[0029] Figure 7 This is a schematic diagram of the precast column inspection tunnel bed during the pouring of the second pouring space in Example 4;

[0030] Figure 8 This is a schematic diagram of the precast column inspection tunnel bed during the leveling of the bottom of the central ditch in Example 4.

[0031] icon:

[0032] 1-Foundation pit, 11-Vertical connecting steel bars, 12-Central drainage ditch, 13-Track bed, 2-Precast column, 21-Reserved steel bars, 3-Storage rack, 31-Support rod, 32-Support leg, 4-Central support, 41-Support frame, 42-Horizontal brace, 43-Hogging mechanism, 431-Hogging part, 432-Connecting part, 5-Track panel, 6-Working platform, 7-First inner formwork, 8-Outer formwork, 9-First pouring space, 10-Second inner formwork, 20-Second pouring space. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Example 1

[0036] like Figures 1-8 As shown, a construction method for a precast column inspection tunnel bed includes the steps of setting up a storage rack 3 in the foundation pit 1 to vertically support the precast column 2 and setting up a central support 4 in the foundation pit 1 to horizontally support the precast column 2. The precast column 2 is provided with a reserved steel bar 21 at the bottom, and the foundation pit 1 is pre-embedded with vertical connecting steel bars 11. After the track panel 5 is erected, the storage rack 3 is removed, and after the track is finely adjusted, the reserved steel bars 21 are welded to the vertical connecting steel bars 11. Then, the precast column 2 is fixed and the track bed is formed by the step of pouring concrete in place.

[0037] Preferably, the storage rack 3 includes two parallel support rods 31. Each support rod 31 has a flat top and steel bar supports 32 arranged at the bottom. The two support rods 31 are placed in the foundation pit 1 to form a through area for the reserved steel bar 21 to pass through. The prefabricated column 2 is supported by the top flat to form the vertical support.

[0038] Specifically, such as Figure 2 As shown, the support rod 31 includes a channel steel component. The bottom of the channel steel component is welded with several steel bar supports 32 in a figure-eight shape. The top plane is provided through the structural plane of the channel steel component. Two support rods 31 are placed in parallel with a spacing that matches the outer dimensions of the precast column 2, forming a through area between the two support rods 31. In this embodiment, the storage rack 3 is placed in the foundation pit 1 in a placement manner. By adjusting the length of the channel steel component, it can support a single precast column 2 or support multiple precast columns 2 arranged longitudinally along the inspection pit at the same time. Since the storage rack 3 is placed in a placement manner, it can not only adjust the size of the through area according to the outer dimensions of the precast column 2 to expand the adaptation range of the storage rack 3, but also flexibly adjust according to the design installation position of the precast column 2. It is easy to install and remove. The precast column 2 is placed on the top plane of the storage rack 3 by gravity ballast, realizing stable vertical support of the precast column 2 in a non-fixed state in the foundation pit 1.

[0039] Preferably, in this embodiment, the storage rack 3 includes two arranged in a row, and the two storage racks 3 correspond to the two columns of prefabricated columns 2 in the longitudinal direction of the inspection tunnel bed 13, and the two columns of prefabricated columns 2 correspond one-to-one in the transverse direction of the inspection tunnel bed 13.

[0040] Preferred, such as Figures 3-4 As shown, the central support 4 includes a support frame 41, a cross brace 42, and a clamping mechanism 43. The width of the support frame 41 is not greater than the transverse design width of the central water ditch 12 of the inspection pit. The support frame 41 is fixed to the longitudinal centerline of the pit 1 by expansion bolts. The clamping mechanism 43 is sleeved on the precast column 2 and connected to the support frame 41 through the cross brace 42 to form the transverse support. The clamping mechanism 43 includes a clamping part 431 and a connecting part 432. The clamping part 431 and the connecting part 432 enclose each other to form a frame-shaped structural component that is adapted to the shape of the precast column 2. The connecting part 432 is fixedly connected to the end of the cross brace 42. The clamping part 431 and the connecting part 432 are detachably connected.

[0041] Specifically, such as Figures 3-4 As shown, the support frame 41 is a steel frame structure. The support frame 41 includes a plate-shaped structure at the bottom. The plate-shaped structure is fixed to the designed position of the central ditch 12 of the inspection pit bed 13 by expansion bolts, temporarily occupying the construction area of ​​the central ditch 12 of the inspection pit. Since the width of the support frame 41 is not greater than the transverse design width of the central ditch 12 of the inspection pit, it can assist in the support of the formwork during the later concrete pouring of the bed, which facilitates the formwork scheme and improves the formwork installation efficiency and cost.

[0042] Preferably, in this embodiment, the cross brace 42 is a steel pipe or steel component, and a connecting part 432 of a plate-shaped structural member is welded to the end of the cross brace 42. The connecting part 432 is reserved with a connecting hole adapted to the clamp part 431. The clamp part 431 is a steel bar bending structural member with a threaded section and a nut at the end. In use, the clamp part 431 is sleeved on the precast column 2, and then passed through the connecting hole reserved on the connecting part 432 and fixed with the nut to form a frame-type structural member, which provides a circumferential ring-shaped connection for the precast column 2, realizes stable lateral support for the precast column 2, and is easy to install and dismantle, facilitating the reuse of the central support 4.

[0043] Preferably, in this embodiment, the cross brace 42 can be two cross braces arranged opposite to each other on both sides of the support frame 41, with the two cross braces 42 respectively connected to the support frame 41, or it can be a single cross brace that passes through the support frame 41. A clamping mechanism 43 is provided at both ends of a single cross brace 42 to simultaneously provide lateral support for the precast columns 2 located in different columns opposite to each other in the foundation pit 1. This not only helps to stabilize the precast columns 2 and prevents them from tipping over, but also helps to ensure that the installation positions of the two opposite precast columns 2 correspond, thereby improving the installation accuracy of the precast columns 2.

[0044] Preferably, in this embodiment, there are multiple support frames 41 arranged longitudinally along the inspection tunnel, so that the number of support frames 41 is consistent with the number of prefabricated columns 2 in a single row. This allows each support frame 41 to support only two prefabricated columns 2 arranged opposite each other, reducing the manufacturing cost of the support frame 41 and facilitating the installation and disassembly of the support frame 41.

[0045] Preferably, in this embodiment, the cross brace 42 is welded and fixed at a position 1-1.5m away from the bottom of the support frame 41, preferably 1.3m, so that the precast column 2 can be laterally supported by the clamping mechanism 43 in the middle and upper part during use, thereby improving the stability of the support and preventing the precast column 2 from tilting.

[0046] Preferably, the reserved reinforcing bar 21 is a vertical reinforcing bar set along the height direction of the precast column 2, and the vertical connecting reinforcing bar 11 is a vertical reinforcing bar set along the depth direction of the foundation pit 1. This reduces the accuracy of the setting position of the vertical connecting reinforcing bar 11 in the foundation pit 1. When the reserved reinforcing bar 21 is close to the vertical connecting reinforcing bar 11, the connection between the precast column 2 and the embedded parts of the foundation pit 1 can be achieved by staggered welding of the side walls of the reserved reinforcing bar 21 and the vertical connecting reinforcing bar 11, thereby fixing the precast column 2. This allows the precast column 2 to stably support the upper track without changing its geometric dimensions during construction. When the reserved reinforcing bar 21 and the vertical connecting reinforcing bar 11 are close together, the connection between the precast column 2 and the embedded parts of the foundation pit 1 can be achieved by staggered welding of the side walls of the reserved reinforcing bar 21 and the vertical connecting reinforcing bar 11. When the vertical connecting steel bars 11 have a horizontal spacing, the connection between the precast column 2 and the pre-embedded parts of the foundation pit 1 can be achieved by lapping the reserved steel bars 21 with the vertical connecting steel bars 11 through auxiliary horizontal bars, thereby fixing the precast column 2. The height of the precast column 2 can be determined by the length of the reserved steel bars 21 at the bottom of the precast column 2. The steel bars support the stability of the precast column 2 in the temporary placement state when it is not fixed. The structure is simple, the preparation is easy, and the length adjustment process is simple. It reduces the installation accuracy requirements of the precast column 2, reduces the difficulty of installing and fixing the precast column 2, and helps to improve the overall construction efficiency.

[0047] This embodiment of a precast column inspection tunnel bed construction method utilizes a storage rack 3 and a bolt-fixed central support 4 to achieve positioning and stable support of the precast columns 2 in a non-fixed state. This ensures the installation stability of the precast columns 2 in a non-fixed state, prevents them from tipping over, and improves their positional accuracy. Simultaneously, by installing and fine-tuning the track before fixing the precast columns 2, the precast columns 2 are in a non-fixed state during track installation and fine-tuning, preventing the installation accuracy of the precast columns 2 from affecting the track installation accuracy. This method simultaneously satisfies the installation accuracy of both the precast columns 2 and the track. Furthermore, the simultaneous fixing of the precast columns 2 and the formation of the tunnel bed through cast-in-place concrete improves overall construction efficiency. The storage rack 3 and central support 4 can be removed at appropriate times, allowing for reuse and reducing the construction cost of the inspection tunnel bed 13. They also assist other processes, further reducing the overall efficiency and cost of the inspection tunnel bed 13 construction, thus achieving a balance between track installation accuracy, construction efficiency, and cost.

[0048] Example 2

[0049] like Figures 1-8 As shown, the construction method of a prefabricated column inspection tunnel bed in this embodiment, based on embodiment 1, further includes the step of providing a working platform 6 by erecting a platform board on the longitudinally adjacent cross braces 42.

[0050] This embodiment describes a construction method for a precast column inspection tunnel bed. The platform board is preferably a 5cm thick wooden board, which is overlapped on two to three adjacent horizontal supports 42 to form a working platform 6. This allows workers to perform process steps such as installing precast column 2 fasteners and fine-tuning track panel 5, and pouring track bed concrete on the working platform 6, thereby improving construction efficiency. Furthermore, it eliminates the need to set up a working plane near the foundation pit 1, reducing the overall construction cost.

[0051] Example 3

[0052] like Figures 1-8 As shown, this embodiment of the construction method for a precast column inspection tunnel bed, based on embodiment 2, the step of casting concrete includes fixing a first inner template 7 on a support frame 41, erecting an outer template 8 on the side wall of the pit 1 to form a first pouring space 9, erecting a second inner template 10 above the formed concrete base in the first pouring space 9, and forming a second pouring space 20 between the second inner template 10 and the outer template 8.

[0053] In this embodiment, a construction method for a precast column inspection tunnel bed is described. The height of the first pouring space 9 is flush with the top elevation of the central ditch 12, forming a layered pouring method with the top elevation of the central ditch 12 as the boundary. The precast column 2 is fixed by the concrete poured in the first pouring space 9, and the remaining structure of the inspection tunnel bed 13, including the side walls, is formed by the concrete poured in the second pouring space 20.

[0054] Specifically, the concrete pouring time of the tunnel bed 13 is divided into segments. The central support 4 can be fully utilized for the installation of the formwork, reducing the installation difficulty of the first inner formwork 7, reducing the formwork erection time and cost of the precast column 2 in the non-fixed state, and allowing the precast column 2 to be fixed as soon as possible after the track installation and fine adjustment, ensuring the stability of the track installation position, and avoiding the fixing process of the precast column 2 from affecting the track installation accuracy.

[0055] Specifically, when the second inner template 10 is installed, the top surface of the concrete base of the first pouring space 9 is flat, making the installation of the second inner template 10 convenient. When the second pouring space 20 is poured, the precast column 2 is fixed by the concrete below, the track installation position is stable, the pouring requirements are reduced, and the pouring of the second pouring space 20 avoids affecting the accuracy of the precast column 2 or the track. This helps to reduce the overall construction efficiency and construction cost of the inspection tunnel bed 13, and achieves the dual function of stable and accurate installation of the precast column 2 and track and concrete pouring process.

[0056] Example 4

[0057] This embodiment describes a construction method for a prefabricated column inspection tunnel bed, such as... Figures 1-8 As shown, the specific steps include S1-S11 performed sequentially:

[0058] S1: Roughen the bottom wall of the foundation pit.

[0059] Specifically, the roughening process includes chiseling pits with a depth of 5-10mm and a spacing of no more than 150mm in a quincunx pattern on the foundation wall of the foundation pit 1. After the roughening is completed, remove debris from the foundation surface and clean the roughened foundation surface to facilitate subsequent inspection of the concrete pouring effect when the tunnel bed 13 is formed.

[0060] S2: Measure and position the center line of the positioning track and the installation position of the precast column 2 according to the design dimensions of the inspection tunnel bed 13. Place the storage rack 3 and install the center support 4 according to the measurement and positioning results.

[0061] Specifically, the top surface of the storage rack 3 is kept horizontal in both the longitudinal and transverse directions, and the support frame 41 is fixed with expansion bolts according to the layout position.

[0062] S3: The prefabricated column 2 is lifted by mechanical equipment and placed on the top surface of the storage rack 3, and is supported laterally by the central support 4.

[0063] Specifically, after the prefabricated column 2 is hoisted to the top of the storage rack 3, it is temporarily fixed by the clamping mechanism 43 of the central support 4.

[0064] S4: A working platform 6 is formed by laying wooden planks on the adjacent cross braces 42.

[0065] Specifically, after the work platform 6 is formed, the operators adjust and stabilize the clamping mechanism 43 on the work platform 6.

[0066] S5: The steel rail is lifted to the top surface of the precast column 2 by mechanical equipment and connected and fixed by fasteners to form the rail panel 5.

[0067] Specifically, after the rails are initially adjusted to a track elevation and gauge not exceeding ±20mm, the rails are connected using quick couplings.

[0068] S6: Remove the storage rack 3 from the lifting rail panel 5 and complete the fine adjustment of the rail panel 5.

[0069] Specifically, the lifting height of track panel 5 is extremely small, just enough for storage rack 3 to be removed from the bottom of precast column 2. After storage rack 3 is removed, the track is fine-tuned according to the track design specifications and design requirements. This mainly includes: allowable deviation of track centerline from benchmark centerline ±2mm, allowable deviation of rail top elevation ±2mm, horizontal difference between left and right rails ≤2mm, height difference between front and rear rail tops ≤1mm, complete close contact between rail base plate and top surface of precast column, rail base slope set at 1 / 40, and rail gap controlled within allowable deviation ±2mm. Other requirements meet GB / T 50299-2018 "Standard for Acceptance of Construction Quality of Underground Railway Engineering" and TB 10413-2018 "Standard for Acceptance of Construction Quality of Railway Track Engineering".

[0070] S7: Weld the reserved reinforcing bar 21 to the vertical connecting reinforcing bar 11. This fixes the precast column 2 and ensures that the geometry of the upper track does not change during construction.

[0071] S8: Tie and set up the steel cage for the space to be poured.

[0072] Specifically, the shape of the steel reinforcement cage is adapted to the shape of the space to be poured in the test tunnel bed 13, and the whole structure is tied together according to the design drawings.

[0073] S9: Install the outer formwork 8 and the first inner formwork 7 in the foundation pit 1 to form the first pouring space 9, and then pour concrete.

[0074] Specifically, the outer formwork 8 is set to fit against the side wall of the foundation pit 1, and the first inner formwork 7 is supported and fixed by the support frame 41. During the concrete pouring process, a vibrator is inserted into the gap between the steel formwork and the reinforcing cage to improve the compactness of the concrete. The height of the first pouring space 9 is flush with the top elevation of the central ditch, which can meet the requirement of complete wrapping of the bottom connecting tooth groove of the precast column 2. At the same time, the track geometry and formwork stability are monitored in real time during the concrete construction process. If the track exceeds the design and specification requirements, it is adjusted immediately. If the formwork runs away or bulges, it is dealt with in a timely manner to ensure the quality of concrete pouring.

[0075] S10: Remove the central support 4 and the first inner template 7, erect the second inner template 10 on the top surface of the concrete base formed in S9 to form the second pouring space 20, and pour concrete.

[0076] Specifically, the pouring control process of the second pouring space 20 is the same as that of the first pouring space 10. The only difference is that the second inner template 10 is erected on the top surface of the concrete base formed in the first pouring space 10, and the concrete surface is finished no less than 3 times to ensure the flatness of the bottom surface of the tunnel bed 13, which is conducive to subsequent construction.

[0077] S11: After removing the second inner template 10, level the bottom of the central ditch 12.

[0078] Specifically, after the concrete pouring of the tunnel bed 13 is completed and reaches the design strength, the formwork is removed. According to the drainage location and the design drainage slope, the backfill height is marked on the side of the concrete base corresponding to the first pouring space 9. The bottom of the central ditch 12 is leveled according to the marked height to ensure smooth drainage.

[0079] This embodiment of a precast column inspection tunnel bed construction method integrates the advantages of stable installation and fixing of precast column 2, high track installation accuracy, reduced difficulty and cost of layered concrete pouring, and cost reduction through the sequential execution of the above-mentioned process flow, thereby achieving low-cost, high-quality, and high-efficiency construction of precast column 2 inspection tunnel bed 13.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for a precast column inspection tunnel bed, characterized in that, The process includes the steps of setting up a storage rack (3) in the foundation pit (1) to vertically support the precast column (2) and setting up a central support (4) in the foundation pit (1) to horizontally support the precast column (2). The precast column (2) has a reserved steel bar (21) at the bottom and a vertical connecting steel bar (11) is embedded in the foundation pit (1). After the track panel (5) is erected, the storage rack (3) is taken out. After the track is finely adjusted, the reserved steel bar (21) is welded to the vertical connecting steel bar (11). Then, the precast column (2) is formed by pouring concrete. The storage rack (3) includes two parallel support rods (31). Each support rod (31) has a flat surface at the top and steel bar supports (32) arranged at the bottom. The two support rods (31) are placed in the foundation pit (1) to form a through area for the reserved steel bar (21) to pass through. The precast column (2) is supported by the top flat surface. The vertical support is formed by the central support (4), which includes a support frame (41), a horizontal brace (42), and a clamping mechanism (43). The width of the support frame (41) is not greater than the horizontal design width of the central water ditch (12) of the inspection pit. The support frame (41) is fixed to the longitudinal centerline of the pit (1) by expansion bolts. The clamping mechanism (43) is sleeved on the precast column (2) and connected to the support frame (41) by the horizontal brace (42) to form the horizontal support. The step of casting concrete includes fixing the first inner template (7) on the central support (4) and erecting the outer template (8) on the side wall of the pit (1) to form the first pouring space (9). The step of casting concrete also includes erecting the second inner template (10) above the concrete matrix formed in the first pouring space (9) and forming the second pouring space (20) between the second inner template (10) and the outer template (8). The method specifically includes the following steps: S1: Roughen the bottom wall of the foundation pit (1); S2: Measure the center line of the positioning track and the installation position of the precast column (2) according to the design dimensions of the inspection tunnel bed (13), and place the storage rack (3) and install the center support (4) according to the measurement and positioning results. S3: The precast column (2) is lifted by mechanical equipment and placed on the top surface of the storage rack (3), and is supported laterally by the central support (4); S4: A working platform (6) is formed by laying wooden planks on the longitudinally adjacent cross braces (42); S5: The steel rail is lifted to the top surface of the precast column (2) by mechanical equipment and connected and fixed by fasteners to form the rail panel (5); S6: Remove the storage rack (3) from the lifting rail panel (5) and complete the fine adjustment of the rail panel (5); S7: Weld the reserved steel bar (21) and the vertical connecting steel bar (11) to fix them. S8: Tie and install the steel reinforcement cage for the space to be poured; S9: Install the outer formwork (8) and the first inner formwork (7) in the foundation pit (1) to form the first pouring space (9) and pour concrete. The height of the first pouring space (9) is level with the top elevation of the central ditch (12). S10: Remove the central support (4) and the first inner template (7), erect the second inner template (10) on the top surface of the S9 formed concrete base to form the second pouring space (20), and pour concrete. S11: After removing the second inner template (10), level the bottom of the central ditch (12).

2. The construction method for a precast column inspection tunnel bed as described in claim 1, characterized in that, The clamping mechanism (43) includes a clamping part (431) and a connecting part (432). The clamping part (431) and the connecting part (432) enclose each other to form a frame-shaped structural component that is adapted to the shape of the precast column (2). The connecting part (432) is fixedly connected to the end of the cross brace (42). The clamping part (431) and the connecting part (432) are detachably connected.

3. The construction method for a precast column inspection tunnel bed as described in claim 1, characterized in that, The reserved reinforcing bars (21) are welded to the vertical connecting reinforcing bars (11) in an alternating manner or connected by auxiliary horizontal bars.

4. The construction method for a precast column inspection tunnel bed as described in claim 1, characterized in that, The concrete pouring includes vibratory pouring.

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