Side top arch type steel mould trolley walking on different sections of lining tunnel

Abstract

The invention relates to a side top arch type steel mould trolley walking on different sections of a lining tunnel, and belongs to the technical field of tunnel construction. The trolley comprises a portal frame body structure, a formwork supporting structure and a formwork assembly. The portal frame main body structure is composed of a plurality of portal frame bodies, each portal frame body comprises a portal frame cross beam and a portal frame stand column with a hydraulic cylinder, height and position adjustment is achieved through segmented control of the hydraulic cylinders, and different section requirements are met. The formwork supporting structure comprises a top formwork rack and a side formwork supporting assembly, the formwork assembly is of an arc-shaped structure formed by splicing an upper formwork, a middle formwork and a lower formwork, and the complex lining construction requirement is met. The side top arch type steel mould trolley walking on the different sections of the lining tunnel is different from a conventional trolley concrete pouring mode, contraction and movement of the longitudinal side top arch template and the annular bottom arch template can be achieved at the same time, and meanwhile the height and the position of the trolley can be adjusted through a hydraulic system on the different sections; and a lining structure with a complex structure can be continuously subjected to concrete pouring.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, in particular to a side-top arch steel formwork trolley which travels on different sections of a lining tunnel. Background Art

[0002] As the country increases its investment in infrastructure, in addition to the large-scale construction of tunnels for high-speed railways and highways, more deep and long-distance water supply and diversion tunnels are widely used, and tunnels for other purposes are also gradually increasing their construction efforts. The requirements for tunnel lining are also higher than those for conventional tunnels. The steel formwork trolley used for concrete lining construction on the inner wall of the tunnel is an indispensable non-standard product for secondary lining during tunnel construction.

[0003] Traditionally used steel formwork trolleys include bottom formwork needle beam type, side top arch type, full circle type, etc. Conventional side top arch type steel formwork trolleys are used for linings with simple structures; but now tunnel lining structures used for different purposes are more complex and diverse in form. For example, in the secondary lining of TBM excavation tunnels, the bottom plate and small side walls are cast in advance before the side top arch lining, and the lining section is also complex and varied depending on the different rock conditions; therefore, conventional side top arch steel formwork trolleys have obvious limitations, and it is difficult to move in tunnels of different sizes, resulting in construction delays and high cost investment. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a side and top arch steel formwork trolley which can travel on different sections of the lining tunnel. Different from the conventional trolley concrete pouring method, it can simultaneously realize the contraction and movement of the longitudinal side and top arch formwork and the annular bottom arch formwork, and at the same time meet the requirements of adjusting the height and position of the trolley through the hydraulic system in different sections, so as to meet the requirements of continuous concrete pouring of complex lining structures.

[0005] The technical solution adopted by the present invention is: A side-top arch steel formwork trolley for traveling on different sections of a lining tunnel, the side-top arch steel formwork trolley for traveling on different sections of a lining tunnel comprises a portal main structure, a formwork support structure installed on the portal main structure, and a formwork assembly installed on the formwork support structure; The main structure of the gantry includes several groups of gantry, each group of gantry includes a gantry crossbeam and gantry columns installed on both sides of the bottom of the gantry crossbeam, and the gantry columns are provided with hydraulic cylinders; The template support structure includes a top template stand installed on the top of the portal main structure, and side template support assemblies installed on both sides of the portal main structure; The template assembly includes an upper template installed on the top template stand, and a middle template and a lower template installed on the side template support assembly. The upper template, the middle template and the lower template are spliced ​​to form an overall arc-shaped template assembly; The side and top arch steel formwork trolley that travels on different sections of the lining tunnel is controlled in sections by several groups of gantry column hydraulic cylinders of the gantry main structure, and can quickly step and slide in discontinuous lining sections to the side and top arch lining work.

[0006] Furthermore, the gantry column of the gantry includes a first hydraulic cylinder and a second hydraulic cylinder which are vertically coaxially arranged, the telescopic rod of the first hydraulic cylinder is fixedly connected to the gantry crossbeam through a gantry connecting seat, and the telescopic rod of the second hydraulic cylinder is fixedly connected to the cylinder body of the first hydraulic cylinder.

[0007] Furthermore, the main structure of the gantry also includes a supporting screw rod arranged between each group of gantry frames, one end of the supporting screw rod is fixedly connected to the gantry connecting seat at the bottom of the gantry column, and the other end is connected to a sliding sleeve mounted on the cylinder body of the first hydraulic cylinder and the telescopic rod of the second hydraulic cylinder.

[0008] Furthermore, the top formwork platform includes a diaphragm box beam fixedly connected to the portal crossbeam, and the diaphragm box beam is provided with a plurality of platform transverse columns which are coaxially arranged and transversely penetrate the diaphragm box beam, and each of the platform transverse columns is provided with a plurality of platform vertical columns which are axially arranged and vertically penetrate the diaphragm box beam.

[0009] Furthermore, the side form support assembly includes an upper longitudinal beam fixedly installed on the upper part of both sides of the portal main structure, and a plurality of side form beams are installed at equal intervals on the upper longitudinal beam. The side form beams are located between two adjacent portal columns. The top of the side form beam is fixedly connected to the top form platform, and the bottoms of all the side form beams located on one side of the portal main structure are connected through a lower longitudinal beam.

[0010] Furthermore, the lower longitudinal beams on both sides of the portal frame main structure are connected by a plurality of lower longitudinal beam supporting screw rods which are coaxially arranged and transversely penetrate the portal frame main structure.

[0011] Furthermore, the upper template includes two arc-shaped steel templates, and the two arc-shaped steel templates are fixedly connected to the horizontal columns and vertical columns of the top template frame.

[0012] Furthermore, the middle formwork and the lower formwork are both an arc-shaped steel formwork, and the middle formwork is installed on the upper longitudinal beam and the side formwork through beam of the side formwork support assembly through a number of side formwork upper support arms and a number of side formwork middle support arms; the lower formwork is installed on the side formwork through beam and lower longitudinal beam of the side formwork support assembly through a number of side formwork middle support arms and a number of side formwork lower support arms.

[0013] Furthermore, the upper support arm of the side mold, the middle support arm of the side mold and the lower support arm of the side mold are all provided with hydraulic cylinders.

[0014] Furthermore, the side-top arch steel formwork trolley that travels on different sections of the lining tunnel also includes a construction platform installed in the main structure of the portal frame and extending longitudinally, and ladders are installed on both sides of the front and rear ends of the construction platform.

[0015] The beneficial effects of the present invention are: 1. Strong adaptability to meet the needs of complex sections: The hydraulic system controls the height and position of the portal column in sections. The trolley can flexibly adjust the overall height and posture to adapt to tunnel sections of different sizes and shapes. This design solves the problem of traditional trolleys having difficulty walking in complex sections, ensuring the continuity and efficiency of construction.

[0016] 2. Flexible contraction and movement of the template to improve construction efficiency: The trolley adopts the design of longitudinal side top arch template and circumferential bottom arch template, combined with hydraulic cylinder drive to achieve rapid contraction and expansion of the template. This function enables the trolley to quickly step and slide between discontinuous lining sections, significantly shortening the construction preparation time and improving construction efficiency.

[0017] 3. Stable structure and strong bearing capacity: The main structure of the portal frame is composed of multiple groups of portal frames, each group of portal frames is connected by beams, columns and supporting screws to form a stable frame structure. The partition box beam and the coaxially arranged horizontal and vertical columns further enhance the rigidity of the top formwork stand, ensuring stability under large span and high load conditions.

[0018] 4. The template components are precisely spliced ​​to ensure the construction quality: The template components are spliced ​​from the upper template, the middle template and the lower template. The overall arc structure can fit closely with the inner wall of the tunnel. The side template support arm is equipped with a hydraulic cylinder, which can accurately adjust the position and angle of the template to ensure the quality of concrete pouring and surface flatness.

[0019] 5. Convenient operation and reduced labor costs: The introduction of the hydraulic system realizes the automatic adjustment of the template and trolley height, reducing the need for manual intervention. At the same time, the design of the construction platform and ladder provides a safe and convenient operating environment for construction personnel, further reducing human resource investment.

[0020] 6. Improved construction safety: The double hydraulic cylinder design of the gantry column and the reinforcement measures of the support screw effectively avoid the shaking and instability of the trolley during operation, improving the safety of construction. In addition, the design of the construction platform and ladder also provides a reliable operating space for construction personnel.

[0021] 7. Save construction time and reduce costs: Since the trolley can quickly adapt to different sections and realize continuous construction, the downtime and equipment adjustment costs caused by section changes are greatly reduced. At the same time, the efficient construction process and high-quality casting effect also indirectly reduce the rework rate and material waste.

[0022] In summary, the side-top arch steel formwork trolley proposed in the present invention not only overcomes the limitations of traditional trolleys in complex section construction, but also significantly improves construction efficiency, quality and safety through technological innovation, provides strong technical support for tunnel lining projects, and has important application value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a schematic diagram of the overall structure of the side-top arch steel mold trolley of the present invention; Figure 2 It is a schematic diagram of the main structure of the side-top arch steel mold trolley door frame of the present invention; Figure 3 It is a schematic diagram of the side-top arch steel mold trolley template support structure of the present invention; In the figure, 1 is the main structure of the gantry, 2 is the formwork support structure, 3 is the formwork assembly, 4 is the gantry, 5 is the gantry crossbeam, 6 is the gantry column, 7 is the hydraulic cylinder, 8 is the top formwork stand, 9 is the side formwork support assembly, 10 is the upper formwork, 11 is the middle formwork, 12 is the lower formwork, 13 is the inner wall of the tunnel, 14 is the first hydraulic cylinder, 15 is the second hydraulic cylinder, 16 is the gantry connecting seat, 17 is the support screw rod, 18 is the sliding sleeve, 19 is the partition type box beam, 20 is the stand horizontal column, 21 is the stand vertical column, 22 is the upper longitudinal beam, 23 is the side formwork through beam, 24 is the lower longitudinal beam, 25 is the lower longitudinal beam support screw rod, 26 is the side formwork upper support arm, 27 is the side formwork middle support arm, 28 is the construction platform, and 29 is the ladder. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In view of the limitations of conventional side-top arch steel formwork trolleys, which are difficult to move in tunnels of different sizes, causing delays in construction and high cost investment, this embodiment provides a side-top arch steel formwork trolley that can move in different sections of lining tunnels. Figure 1As shown, the side-top arch steel formwork trolley that travels on different sections of the lining tunnel includes a portal main structure 1, a formwork support structure 2 installed on the portal main structure 1, and a formwork assembly 3 installed on the formwork support structure 2. Among them, the portal main structure 1 is the main load-bearing frame of the entire trolley, providing overall support and stability; the formwork support structure 2 provides an installation base for the formwork assembly 3 and ensures the precise position and angle of the formwork; the formwork assembly 3 directly contacts the inner wall 13 of the tunnel, is used for concrete pouring and molding, and ensures the quality of the lining.

[0027] Specifically, Figure 1 and Figure 2 As shown, the main structure 1 of the gantry in this embodiment includes eight groups of gantry 4, each group of gantry 4 includes a gantry crossbeam 5, and a gantry column 6 installed on both sides of the bottom of the gantry crossbeam 5, and a hydraulic cylinder 7 is provided on the gantry column 6. The gantry crossbeam 5 is welded by H1000×300H steel, and its wing plate is made of δ=14㎜ steel plate, and the web plate is made of δ=12㎜ steel plate. The gantry crossbeam 5 connects the gantry columns 6 on both sides to form a stable horizontal frame, transfer load and enhance lateral rigidity. The gantry column 6 in this embodiment includes a first hydraulic cylinder 14 and a second hydraulic cylinder 15 arranged vertically and coaxially, and the first hydraulic cylinder 14 and the second hydraulic cylinder 15 are both hydraulic cylinders with a stroke of 1000mm; the telescopic rod of the first hydraulic cylinder 14 is fixedly connected to the gantry crossbeam 5 through the gantry connecting seat 16, and the telescopic rod of the second hydraulic cylinder 15 is fixedly connected to the cylinder body of the first hydraulic cylinder 14. The height of the gantry column 6 is adjusted by the hydraulic cylinder 7 to adapt to different cross-sectional sizes while bearing the weight of the superstructure; the coaxially arranged first hydraulic cylinder 14 and second hydraulic cylinder 15 can control the support points in sections to achieve flexible adjustment and rapid stepping and sliding of the trolley between different cross-sections.

[0028] Further, as a preferred technical solution of this embodiment, in order to prevent the main structure 1 of the gantry from deforming, as Figure 1 and Figure 2 As shown, the main structure 1 of the gantry in this embodiment also includes a support screw rod 17 arranged between each group of gantry 4, and the support screw rod 17 is formed by threading a Tr60×8 screw rod and a φ89×6 seamless steel pipe; one end of the support screw rod 17 is fixedly connected to the gantry connection seat 16 at the bottom of the gantry column 6, and the other end is connected to a sleeve 18 sleeved on the cylinder body of the first hydraulic cylinder 14 and the telescopic rod of the second hydraulic cylinder 15. The support screw rod 17 connects the gantry column 6 and the sleeve 18, and enhances the stability of the gantry column 6 and prevents the main structure 1 of the gantry from deforming without affecting the operation of the first hydraulic cylinder 14 and the second hydraulic cylinder 15.

[0029] like Figure 1 and Figure 3As shown, the formwork support structure 2 in this embodiment includes a top formwork stand 8 installed on the top of the portal main structure 1, and side formwork support assemblies 9 installed on both sides of the portal main structure 1. The top formwork stand 8 includes a diaphragm box beam 19 fixedly connected to the portal cross beam 5, and the diaphragm box beam 19 is provided with eight diaphragm transverse columns 20 arranged coaxially and laterally penetrating the diaphragm box beam 19, and each diaphragm transverse column 20 is provided with four diaphragm vertical columns 21 arranged axially and vertically penetrating the diaphragm box beam 19; wherein, the diaphragm transverse columns 20 and the diaphragm vertical columns 21 are both welded with 20b# I-beams. The upper formwork 10 is supported by the diaphragm box beam 19, the diaphragm transverse columns 20 and the vertical columns to enhance rigidity and ensure the stability and bearing capacity of the top formwork.

[0030] like Figure 1 and Figure 3 As shown, the side form support assembly 9 of the formwork support structure 2 includes an upper longitudinal beam 22 fixedly installed on the upper part of both sides of the portal main structure 1, the upper longitudinal beam 22 adopts H-shaped steel of H294×200, and eight side form beams 23 are installed at equal intervals on the upper longitudinal beam 22; the side form beam 23 is welded by two 20# channel steels, the side form beam 23 is located between two adjacent portal columns 6, and the top of the side form beam 23 is fixedly connected to the top formwork stand 8; the bottoms of all the side form beams 23 located on one side of the portal main structure 1 are connected by a lower longitudinal beam 24; the lower longitudinal beam 24 is a welded box beam with a height of 600㎜ and a width of 500㎜, and adopts δ=14㎜ steel plate as the wing plate and δ=12㎜ steel plate as the web plate for welding; the side form support assembly 9 provides stability and bearing capacity for the installation of the middle and lower formworks.

[0031] Further, as a preferred technical solution of this embodiment, in order to ensure the stability of the side mold support assembly 9, as Figure 1 and Figure 3 As shown, the lower longitudinal beams 24 on both sides of the portal main structure 1 in this embodiment are connected by eight coaxially arranged lower longitudinal beam support screw rods 25 that transversely penetrate the portal main structure 1. The lower longitudinal beam support screw rods 25 are formed by threading a Tr70×8 screw rod and a φ102×6 seamless steel pipe. After the lower longitudinal beam support screw rods 25 are connected to the lower longitudinal beams 24 on both sides, the stability of the side mold support assembly 9 can be ensured.

[0032] like Figure 1 and Figure 3As shown, the template assembly 3 in this embodiment includes an upper template 10 installed on the top template stand 8, and a middle template 11 and a lower template 12 installed on the side template support assembly 9. Among them, the upper template 10 includes two arc-shaped steel templates, and the two arc-shaped steel templates are fixedly connected to the horizontal column 20 and the vertical column 21 of the top template stand 8. The middle template 11 and the lower template 12 are both arc-shaped steel templates. The middle template 11 is installed on the upper longitudinal beam 22 and the side template through beam 23 of the side template support assembly 9 through eight sets of side template upper support arms 26 and eight sets of side template middle support arms 27; the lower template 12 is installed on the side template through beam 23 and the lower longitudinal beam 24 of the side template support assembly 9 through eight sets of side template middle support arms 27 and eight sets of side template lower support arms. Figure 3 In the figure, the middle support arm 27 and the lower support arm of the side form are not shown. The upper support arm 26, the middle support arm 27 and the lower support arm of the side form are all equipped with hydraulic cylinders to control the circular contraction and extension of the formwork. The upper formwork 10, the middle formwork 11 and the lower formwork 12 are all made of δ=10㎜ steel plate for the panel. The upper formwork 10, the middle formwork 11 and the lower formwork 12 are spliced ​​to form a formwork assembly 3 with an overall arc structure to ensure a close fit with the inner wall 13 of the tunnel; the plug formwork of the formwork assembly 3 is made of a wooden formwork, which is not shown in the figure and is fixed by tie bars.

[0033] The side top arch steel formwork trolley traveling on different sections of the lining tunnel is controlled in sections by the gantry columns 6 hydraulic cylinders 7 of the eight groups of gantry main structures 1, and can quickly step and slide in discontinuous lining sections to the side top arch lining work. Its working principle is: like Figure 1 As shown, the front four groups of portal frame main structures 1 of the eight groups of portal frame main structures 1 are supported on the small-section tunnel, the rear four groups of portal frame main structures 1 are supported on the large-section tunnel, and the cylinder body of the second hydraulic cylinder 15 of the portal frame column 6 of the eight groups of portal frame main structures 1 is supported on the ground, so as to meet the requirements of rapid side-top arch lining work in discontinuous lining sections. After the work is completed, if it is necessary to move into the small-section tunnel, the first hydraulic cylinder 14 and the second hydraulic cylinder 15 of the portal frame column 6 of the rear four groups of portal frame main structures 1 are retracted, so that the second hydraulic cylinder 15 is out of contact with the bottom ground of the large-section tunnel, and the side-top arch steel mold trolley can move into the small-section tunnel. Conversely, if it is necessary to move into the large-section tunnel, the first hydraulic cylinder 14 and the second hydraulic cylinder 15 of the portal frame column 6 of the front four groups of portal frame main structures 1 are retracted, so that the side-top arch steel mold trolley moves into the large-section tunnel. It should be noted that the side and top arch type steel mold trolley can be equipped with a stepping cylinder at the gantry column 6 to meet the stepping movement of the side and top arch type steel mold trolley; other technical means can also be used, such as cooperating with a rail car to achieve stepping movement along the tunnel; the movement of the steel mold trolley is a conventional technology in this field and will not be described in detail here.

[0034] In addition, as the preferred technical solution of this embodiment, considering the convenience of construction, Figure 1 As shown, the side-top arch steel formwork trolley that travels on different sections of the lining tunnel also includes a construction platform 28 installed in the main structure of the portal frame 1 and extending longitudinally, and ladders 29 are installed on both sides of the front and rear ends of the construction platform 28. The construction platform 28 and the ladder 29 provide a safe and convenient operating space for construction personnel, which is convenient for equipment maintenance and construction operations.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A side-top arch steel formwork trolley for traveling on different sections of a lining tunnel, characterized in that: The side-top arch steel formwork trolley traveling on different sections of the lining tunnel comprises a portal main structure, a formwork support structure installed on the portal main structure, and a formwork assembly installed on the formwork support structure; The main structure of the gantry includes several groups of gantry, each group of gantry includes a gantry crossbeam and gantry columns installed on both sides of the bottom of the gantry crossbeam, and the gantry columns are provided with hydraulic cylinders; The template support structure includes a top template stand installed on the top of the portal main structure, and side template support assemblies installed on both sides of the portal main structure; The template assembly includes an upper template installed on the top template stand, and a middle template and a lower template installed on the side template support assembly. The upper template, the middle template and the lower template are spliced ​​to form an overall arc-shaped template assembly; The side and top arch steel formwork trolley that travels on different sections of the lining tunnel is controlled in sections by several groups of gantry column hydraulic cylinders of the gantry main structure, and can quickly step and slide in discontinuous lining sections to the side and top arch lining work.

2. The side-top arch steel formwork trolley for traveling on different sections of the lining tunnel according to claim 1 is characterized in that: The gantry column of the gantry includes a first hydraulic cylinder and a second hydraulic cylinder which are vertically coaxially arranged. The telescopic rod of the first hydraulic cylinder is fixedly connected to the gantry crossbeam through a gantry connecting seat, and the telescopic rod of the second hydraulic cylinder is fixedly connected to the cylinder body of the first hydraulic cylinder.

3. The side-top arch steel formwork trolley for traveling on different sections of the lining tunnel according to claim 2 is characterized in that: The main structure of the gantry also includes a supporting screw rod arranged between each group of gantry frames, one end of the supporting screw rod is fixedly connected to the gantry connecting seat at the bottom of the gantry column, and the other end is connected to a sliding sleeve mounted on the cylinder body of the first hydraulic cylinder and the telescopic rod of the second hydraulic cylinder.

4. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 1 is characterized in that: The top formwork platform includes a diaphragm box beam fixedly connected to the portal crossbeam, and a plurality of platform transverse columns coaxially arranged and laterally penetrating the diaphragm box beam are arranged in the diaphragm box beam, and a plurality of platform vertical columns axially arranged and vertically penetrating the diaphragm box beam are arranged on each of the platform transverse columns.

5. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 1 is characterized in that: The side form support assembly includes an upper longitudinal beam fixedly installed on the upper part of both sides of the portal main structure, and a plurality of side form beams are installed on the upper longitudinal beam at equal intervals. The side form beams are located between two adjacent portal columns. The top of the side form beam is fixedly connected to the top form platform, and the bottoms of all the side form beams located on one side of the portal main structure are connected by a lower longitudinal beam.

6. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 5 is characterized in that: The lower longitudinal beams on both sides of the portal frame main structure are connected by a plurality of lower longitudinal beam supporting screw rods which are coaxially arranged and transversely penetrate the portal frame main structure.

7. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 4 is characterized in that: The upper template comprises two arc-shaped steel templates, and the two arc-shaped steel templates are fixedly connected to the horizontal columns and vertical columns of the top template frame.

8. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 5 is characterized in that: The middle template and the lower template are both an arc-shaped steel template. The middle template is installed on the upper longitudinal beam and the side template through beam of the side template support assembly through a number of side template upper support arms and a number of side template middle support arms; the lower template is installed on the side template through beam and lower longitudinal beam of the side template support assembly through a number of side template middle support arms and a number of side template lower support arms.

9. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 8 is characterized in that: The upper supporting arm of the side mold, the middle supporting arm of the side mold and the lower supporting arm of the side mold are all provided with hydraulic cylinders.

10. The side-top arch steel formwork trolley for traveling on different sections of a lining tunnel according to claim 1, characterized in that: The side-top arch steel formwork trolley that travels on different sections of the lining tunnel also includes a construction platform that is installed in the main structure of the portal frame and extends longitudinally, and ladders are installed on both sides of the front and rear ends of the construction platform.

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