CN111980165A

CN111980165A - Large-span net rack external-expanding splicing integral jacking construction method

Info

Publication number: CN111980165A
Application number: CN202010785410.7A
Authority: CN
Inventors: 于景民; 徐超; 马海龙; 赵宝重; 张�浩; 高磊
Original assignee: Second Construction Co Ltd of China Construction Eighth Engineering Division Co Ltd
Current assignee: Second Construction Co Ltd of China Construction Eighth Engineering Division Co Ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2020-11-24

Abstract

The invention discloses a construction method for externally expanding, splicing and integrally jacking a large-span net rack, which belongs to the field of building construction, and aims to solve the technical problems of reducing the construction difficulty of a spherical shell, a cylindrical shell, a flat plate and various special-shaped stadium large-span net rack structures under complex conditions, reducing high-construction operation, improving safety and simultaneously ensuring construction quality, wherein the technical scheme is as follows: the construction method comprises the following specific steps: assembling and jacking: assembling the net rack on the ground, installing a jacking bracket when the net rack is assembled to the position of the stand, and stopping jacking when the net rack is jacked by the jacking bracket to a set height to meet the assembly of the next grid; symmetrically expanding and assembling: after the jacking operation is stopped, symmetrically expanding and assembling the completed space rigidity units from the center of the net rack, so that the net rack continuously extends to the periphery; adjusting the number and the positions of jacking points: when the net rack is expanded and spliced outwards, the number and the positions of the jacking points of the net rack are adjusted according to the calculation result; and (4) unloading and dismantling.

Description

Large-span net rack external-expanding splicing integral jacking construction method

Technical Field

The invention relates to the field of building construction, in particular to a construction method for externally expanding, splicing and integrally jacking a large-span net rack, which is particularly suitable for projects with the lower chord elevation of 25m and below of spherical shells, cylindrical shells, flat plates and various special-shaped net racks and particularly aims at a net rack structure formed by mixed assembly of welding joints, bolt spherical joints and welding spherical joints.

Background

Along with the construction of large stadiums, theaters and cultural and sports centers in various regions, various large-span steel structure net racks are increasingly applied to building roofs. The steel structure rack of this kind of engineering on the one hand span is big, the volume is many and highly high, on the other hand because the rack often erects at the center of venue, often has the peripheral hoist and mount degree of difficulty of hoisting machinery, the higher condition of cost in the construction.

Therefore, how to reduce the construction difficulty under the complex condition of a spherical shell, a cylindrical shell, a flat plate and various special-shaped stadium large-span net rack structures, reduce high-labor operation, improve safety and ensure construction quality is a technical problem to be solved urgently at present.

Disclosure of Invention

The technical task of the invention is to provide a construction method for externally expanding, splicing and integrally jacking a large-span net rack, which solves the problems of how to reduce the construction difficulty of a spherical shell, a cylindrical shell, a flat plate and various special-shaped stadium large-span net rack structures under complex conditions, reduce high-labor operation, improve safety and ensure construction quality.

The technical task of the invention is realized by the following method, and the construction method for the outward expansion, assembly and integral jacking of the large-span net rack specifically comprises the following steps:

assembling and jacking: assembling the net rack on the ground, installing a jacking support when the net rack is assembled to the position of the stand, jacking the net rack by using the jacking support to a set height (different jacking heights are determined according to civil engineering conditions) to meet the requirement of next grid assembly, and stopping jacking;

symmetrically expanding and assembling: after the jacking operation is stopped, symmetrically expanding and assembling the completed space rigidity units from the center of the net rack, so that the net rack continuously extends to the periphery;

adjusting the number and the positions of jacking points: when the net rack is expanded and spliced outwards, the number and the positions of the jacking points of the net rack are adjusted according to the calculation result;

unloading and dismantling: repeatedly assemble and jacking, the symmetry expands outward and assembles and adjust jacking point quantity and position, after the rack rises to above the position of structure elevation, the rack is accomplished the back and is inlayed the post top member, uninstallation and demolish jacking device, and the rack construction is accomplished.

Preferably, the construction method comprises the following process flows:

s1, preparation before construction;

s2, assembling net racks;

s3, arranging jacking points, and installing a jacking device;

s4, quality and safety inspection;

s5, trial jacking;

s6, formally jacking;

s7, outward expanding assembly and circular lifting;

s8, lifting to the right and butting the support;

s9, synchronous unloading;

and S10, removing the jacking device, and finishing the installation.

Preferably, the preparation before construction in step S1 is as follows:

s101, counting the net rack materials which have entered the field, stacking balls and rods in a classified mode respectively, and checking the machining sizes of the balls and the rods to guarantee the installation accuracy, otherwise, the net rack materials cannot be used;

s102, cleaning up sundries stacked on site to ensure smooth construction;

s103, calculating the number and the positions of the jacking frames by using MIDAS according to the site condition and the structure appearance, and performing stress and deformation accounting; after the net rack is checked and calculated, if the super-stress rod is found, temporary reinforcement is carried out, namely, the outer side of the rod piece is reinforced by a clamp;

s104, releasing the mounting position of the jacking frame and the projection position of part of the lower chord ball according to the position of the scheme, and positioning the position of the lower chord ball with the concrete structure at the position of the column beam;

s105, checking jacking equipment to ensure that the equipment runs normally in the jacking process;

s106, checking the foundation of the jacking equipment, wherein the foundation has enough strength, otherwise, the foundation is processed in advance.

Preferably, the assembling of the net rack in the step S2 is as follows:

s201, installing a lower chord plane net rack, and specifically comprising:

s20101, centering a column axis and a center line, rechecking elevation by using a level gauge, and correcting errors;

s20102, forming a longitudinal plane grid by a lower chord ball and a rod in the central area of the installation net rack; arranging temporary supporting points to ensure the equality of the lower string ball; finding out the slope bottom on the temporary pivot when an arching requirement exists;

s20103, mounting web members and an upper chord ball between first units, wherein a first cone is a small unit with one ball and four web members, and is screwed and fixed with a lower chord ball after being in place;

s20104, starting the second cone to be a triangular cone which is firstly provided with a ball, a chord and two web members, then filling the other two web members, and gradually circularly installing the net rack of the first unit;

s20105, checking the net rack, the grid size and the longitudinal size and rise of the net rack; meanwhile, the position of the net rack is checked, and if the net rack is in and out, the position and the height of the temporary fulcrum are adjusted to calibrate the positioning size of the net rack;

s202, installing an upper chord inverted triangular grid, and specifically comprising:

s20201, starting from the side span, firstly forming a triangular pyramid of the first sphere-first upper chord second web member, and then forming a quadrangular pyramid of the first sphere-second upper chord second web member;

s20202, supporting the two diagonal web members on the lower chord ball, and tensioning the upper chord member above to enable the upper chord member to gradually approach the mounted upper chord ball (push cone) to be screwed, adjusted and fastened;

s20203, in the installation process of the net rack, whether the axis of the net rack deviates from the axis of the building foundation is checked at any time, and the adjustment is carried out at any time;

s20204, checking the integral deflection of the net rack, strictly controlling the sizes of the upper chord and the lower chord of the net rack, and ensuring that each bolt is screwed in place;

s20205, the net rack is inspected at any time in the installation process for the sinking condition of each temporary supporting point, and if the sinking condition exists, the net rack is reinforced in time.

Preferably, the net rack is a steel net rack, and the assembling process of the steel net rack is as follows:

(1) positioning a first lower chord grid temporary supporting point on the ground;

(2) assembling the first grid lower chord member on the temporary supporting point;

(3) assembling an upper chord ball and a net rack web member connected with the upper chord ball into a whole and assembling a lower chord unit in place into an integral structure;

(4) assembling a lower chord member of the next unit grid frame;

(5) assembling an upper chord ball, a net rack web member connected with the upper chord ball and an upper chord member on one side into a whole and assembling a lower chord unit in place into an integral structure;

(6) repeating the step (4) and the step (5) to continue assembling the other grid components;

(7) and assembling the whole structure.

Preferably, in the step S3, in the process of determining the position of the jacking device, it is ensured that each node ball is uniformly stressed in the jacking process, and the bottom of the jacking device is provided with a steel plate support to avoid the pressure of the jacking device on the supporting surface from being too large;

when the jacking device is arranged on the concrete structure surface, the supporting points are arranged at the concrete columns and the concrete beams, and whether reinforcement is needed or not is determined through checking calculation;

when the supporting point is not placed at the main beam, a reserved hole is made before the floor slab is lifted, the ground is processed, meanwhile, the bearing capacity of the ground is checked, it is ensured that the ground settlement can not affect the construction quality and safety, and then the jacking device penetrates through the reserved hole to stand on the ground.

More preferably, the formal jacking in step S6 is as follows:

s601, rechecking the elevations and deformation conditions of different square points of the net rack by using a total station, and determining the allowable deviation of each elevation point according to the construction check calculation of the net rack;

s602, pausing each time of jacking for about 1.5m, checking the deviation of each point of the net rack, jacking the net rack to a preset elevation in times and then fixing;

s603, after the net rack is jacked to a preset elevation and fixed, checking the integral displacement and torsion deviation of the net rack; when large deviation exists, a concrete structure is used as a pulling node, and chain inversion adjustment is carried out;

s604, the lower bracket is stressed when the height is increased, a section of support frame is added when the piston rod is completely extended out, the piston rod retracts after the related bolt is screwed, the upper bracket is stressed, when the piston rod retracts completely, the lower bracket retracts to a position capable of being stressed, a cross rod (stress rod) is moved upwards, and the cross rod corresponds to the position of a stress beam of the lower bracket;

s605, when the upper bracket is stressed during dismantling, the piston rod retracts to be not stressed, the cross rod (stress rod) is moved downwards, the position of the cross rod is required to correspond to the position of the stress beam of the lower bracket, the piston rod extends out, the lower bracket is moved to the position of the next support frame, the lower bracket is stressed, the upper bracket is not stressed, and a section of support frame is dismantled.

Preferably, the step S7 of externally expanding, assembling and circularly lifting is as follows:

s701, stopping jacking when the net rack is jacked to a set height and the requirement of outward expansion and assembly of the net rack can be met;

s702, carrying out outward expansion assembly on the assembled miniature grid units through hoisting; meanwhile, according to the external expansion size, a jacking device is added at a determined position in time according to calculation;

s703, after the external expansion assembling and jacking devices are installed, performing trial jacking again to ensure that the jacking devices installed front and back are synchronous;

s704, paying attention to installation, adjustment and application of the guy rope and the tied steel wire rope in the processes of outward expanding assembly and circulating jacking; when the lifting device is lifted to the height of 3 m, the inclined support is added to the lifting device to ensure the integral stability; when the lifting is carried out to the height of 10 meters, the guy cables are adopted, the cable-stayed angle of the guy cables is not less than 30 degrees, and the arrangement positions are four corners of the lifting truss.

Preferably, the lifting to the position and butting to the support in the step S8 are as follows:

s801, expanding and assembling the net rack to a preset range, and stopping jacking after jacking to the elevation of the support;

s802, rechecking and adjusting the elevation, the displacement and the torsional deviation of the net rack, and completing the support rod piece embedding work after the adjustment is in place; simultaneously, the installation and elevation adjustment of the support are carried out, so that the butt joint quality of the net rack and the support is ensured;

and S803, after the net rack falls down and the support is stressed, assembling the residual overhanging node balls and the rod pieces until the net rack is completely assembled.

Preferably, the synchronous unloading in step S9 is specifically as follows:

s901, measuring the elevation of the middle node of the net rack before unloading;

s902, synchronously descending the jacking device by 10mm each time under the control of a computer, observing whether the jacking device is separated from the net rack, and measuring the elevation change condition of the middle node of the net rack until the jacking device is completely separated from the net rack;

and (S10) removing the jacking device, wherein the installation is completed as follows:

s1001, after the two sections of the jacking devices are disassembled, integrally and horizontally hanging the rest support frames on the ground by using a crane;

s1002, dismantling the steel pipe from the ground, stacking the steel pipe neatly and transporting the steel pipe to the outside of the field.

The construction method for externally expanding, splicing and integrally jacking the large-span net rack has the following advantages:

the invention successfully solves the construction problem under the complex condition of the venue large-span net rack structure, and the engineering can be well controlled in the aspects of construction period, quality, cost and safety by applying the invention, thereby obtaining good social and economic benefits;

the invention adopts the 800 × 800mm standard knot as the bearing device, which is convenient for installation and disassembly, and the standard knot adopts the circular tube to be welded with the flange, which is convenient for installation;

the core equipment of the hydraulic synchronous lifting technology is controlled by a computer, fully automatically completes multiple functions of synchronous lifting, load balancing, attitude correction, stress control, operation locking, process display, fault alarm and the like, and is modern advanced equipment integrating machines, electricity, liquid, sensors and computers;

the implementation of the invention can ensure that the net rack is assembled on the ground or in a lower space, the high-altitude operation is less, the safety risk is reduced, the quality monitoring is convenient, each point and surface can be embodied, the hidden danger is reduced, and the quality is ensured;

the method adopts a jacking method for installation, avoids the influence of scaffold erection on the construction period, reduces the measure cost, and meanwhile, most of work is finished on the ground, so that the method is hardly influenced by weather such as wind, rain and the like, the working efficiency is improved, and the construction period is shortened;

sixthly, for the net racks arranged on the stadiums and multi-storey buildings provided with stands, auxiliary rooms or basements, the difficulty that the structural type cannot be lifted integrally at one time is solved;

the invention reduces the engineering cost, shortens the construction period and creates conditions for the scheduled delivery of the engineering. The jacking process does not generate noise and various garbage, all jacking devices can be recycled, and the environment-friendly concept is met; the application of the net rack jacking method obtains higher attention in the industry, meets the observation and communication of external units for many times, and plays a good role in propaganda of enterprises.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a flow chart of a construction method for externally expanding, assembling and integrally jacking a large-span net rack;

FIG. 2 is a schematic structural view of node reinforcement;

FIG. 3 is a schematic view of the positioning of the support pad during the assembly of the steel mesh frame;

FIG. 4 is a schematic view of the assembly of the first grid lower chord member during the assembly of the steel mesh frame;

FIG. 5 is a schematic view of the steel net frame assembly process with the lower chord unit assembled in place to form an integral structure;

FIG. 6 is a schematic view of the assembly of the lower chord member of the next unit grid frame during the assembly of the steel grid frame;

FIG. 7 is a schematic view of the steel truss assembly process with the lower chord units in place assembled to form an integral structure;

FIG. 8 is a schematic view of the assembly of the remaining grid members during the assembly of the steel grid;

FIG. 9 is a schematic view of the entire structure after assembly;

FIG. 10 is a schematic view of a steel plate base of the jacking device;

FIG. 11 is a schematic illustration of the basic process of the jacking device;

FIG. 12 is a schematic illustration of a jacking frame installation process;

FIG. 13 is a schematic diagram of a cylinder installation process;

fig. 14 is a schematic drawing of a guy rope.

Detailed Description

The construction method for the outward expanding, assembling and integral jacking of the large-span net rack is described in detail below with reference to the attached drawings and specific embodiments of the specification.

Example 1:

the invention discloses a construction method for externally expanding, splicing and integrally jacking a large-span net rack, which comprises the following steps:

(II) symmetrical outward expansion assembling: after the jacking operation is stopped, symmetrically expanding and assembling the completed space rigidity units from the center of the net rack, so that the net rack continuously extends to the periphery;

(III) adjusting the number and the positions of jacking points: when the net rack is expanded and spliced outwards, the number and the positions of the jacking points of the net rack are adjusted according to the calculation result;

(IV) unloading and dismantling: repeatedly assemble and jacking, the symmetry expands outward and assembles and adjust jacking point quantity and position, after the rack rises to above the position of structure elevation, the rack is accomplished the back and is inlayed the post top member, uninstallation and demolish jacking device, and the rack construction is accomplished.

Example 2:

as shown in the attached drawing 1, the large-span net rack outward-expanding splicing integral jacking construction method has the following process flow:

s1, preparation before construction; the method comprises the following specific steps:

s102, cleaning up sundries stacked on site to ensure smooth construction;

s103, calculating the number and the positions of the jacking frames by using MIDAS according to the site condition and the structure appearance, and performing stress and deformation accounting; after the net rack is checked and calculated, if the super-stress rod is found, temporary reinforcement is carried out, namely the outer side of the rod piece is reinforced by a clamp, as shown in the attached figure 2;

S2, assembling net racks; the net rack assembly is as follows:

s201, installing a lower chord plane net rack, and specifically comprising:

Wherein the net rack is made of steel net rack, as shown in the attached figures 3-9, the assembling process of the steel net rack is as follows:

(4) assembling a lower chord member of the next unit grid frame;

(7) and assembling the whole structure.

S3, arranging jacking points, and installing a jacking device; in the position determining process of the jacking device, each node ball is ensured to be stressed uniformly in the jacking process, and the bottom of the jacking device is provided with a steel plate support to avoid overlarge pressure of the jacking device on a supporting surface, as shown in the attached drawing 10;

when the supporting point is not placed at the main beam, a reserved hole is made before the floor slab is lifted, the ground is processed, as shown in the attached drawing 11, meanwhile, the bearing capacity of the ground is checked, it is ensured that the ground settlement can not affect the construction quality and safety, and then the jacking device penetrates through the reserved hole to stand on the ground.

S4, quality and safety inspection; the method comprises the following specific steps: before jacking the net rack, quality and safety inspection needs to be carried out on the assembled net rack, and the quality is mainly used for inspecting and rechecking assembled node balls, rod pieces, welding seams, axes and the like. The safety aspect is mainly to check the in-place condition of the jacking device, such as a jack, a cable rope, a computer monitoring control system and the like, and in addition, whether other facilities obstruct the jacking of the net rack, whether the net rack is separated from other structures and the like needs to be noticed.

S5, trial jacking; the method comprises the following specific steps: before the net rack is jacked, all constructors are subjected to detailed technical and safety bottom crossing, and jacking is started for the first time after field equipment is checked to be correct. All jacking power devices start synchronous jacking under unified command, and jacking control is cooperatively performed by a wired network computer. The height of the trial jacking is controlled to be about 500mm, so that the assembled net rack is separated from the supporting point and is in a suspended state.

S6, formal jacking: after the jacking test is finished, checking in time to determine whether a problem exists, if all indexes are normal, carrying out formal jacking directly, and carrying out formal jacking and the jacking test operation method; the method comprises the following specific steps:

s605, when the upper bracket is stressed during dismantling, the piston rod retracts to be not stressed, the cross rod (stress rod) is moved downwards, the position of the cross rod is required to correspond to the position of the stress beam of the lower bracket, the piston rod extends out, the lower bracket is moved to the position of the next support frame, the lower bracket is stressed, the upper bracket is not stressed, and a section of support frame is dismantled. The lifting, mounting, and conversion process of the jacking frame is shown in figures 12 and 13.

Wherein, the jacking process is specifically as follows:

firstly, after the construction of a concrete structure is completed, installing a jacking bracket according to the plane position of a jacking point;

secondly, assembling the net rack inside the stand on the ground, and after the net rack is integrally assembled, carrying out self-checking on the size and the welding quality of the net rack. Jacking operation can be carried out after no error, and when the height of the jacking operation meets the next grid pairing, jacking is stopped, and the grid is paired and welded;

thirdly, jacking is started, the jacking is carried out to 3.5m, and the rod piece extends outwards;

fourthly, after the rod piece is installed, continuing jacking for 7.1m, and extending the rod piece outwards;

and fifthly, after the rod piece is installed, continuing jacking for 9.4m and extending the rod piece outwards. Meanwhile, the number and the positions of the jacking points are adjusted;

sixthly, repeating the step I-fifthly, after jacking to the position above the elevation 20.6m of the support, mounting the support, and falling the jacking frame to stress the support; after the support is stressed and the structure is stable, the suspended net frame is repaired by using a truck crane until the net frame is completely finished.

S7, outward expanding assembly and circular lifting; the method comprises the following specific steps:

s704, paying attention to installation, adjustment and application of the guy rope and the tied steel wire rope in the processes of outward expanding assembly and circulating jacking; when the lifting device is lifted to the height of 3 m, the inclined support is added to the lifting device to ensure the integral stability; when the jacking frame is jacked to a height of 10 meters, the guy cable is adopted, the diagonal pulling angle of the guy cable is not less than 30 degrees, the arrangement positions are four corners of the jacking truss, and the standard knot of the jacking truss is provided with a connecting plate for connecting a steel support or the guy cable, as shown in the attached drawing 14.

S8, lifting to the right and butting the support; the method comprises the following specific steps:

S9, synchronous unloading; the method comprises the following specific steps:

and S10, removing the jacking device, and finishing the installation. The method comprises the following specific steps:

The environmental protection measures are as follows:

1) in the process of assembling the net rack, the welding operation surface keeps good ventilation and slurry exchange, so that the harm of smoke dust to operators is prevented;

2) and closed and container type management should be carried out when the net rack is sprayed with the paint, so that air pollution is prevented. The release amount of the paint thinner is strictly controlled, and the rest part is timely recycled to prevent secondary pollution;

3) cleaning and sprinkling water in time when the vehicle enters and exits the construction site, and cleaning tires and a vehicle body before the transport vehicle leaves the construction site;

4) the components are stored in different regions according to the types and the installation sequence, and are required to be flat, padded, dry and free of accumulated water, so that the materials are prevented from rusting.

The specific implementation case is as follows:

1) and the jacking process adopted in the project of the gymnasium of Beijing university of chemical industry avoids the erection of full hall scaffolds, saves the measure cost, and saves the cost by 95 ten thousand yuan through measurement and calculation. The investment of a large-scale crawler crane can be reduced by the installation of the jacking process, only 1 crawler crane with 25t is invested in the engineering site, and the reduction of the machine shift cost is 25 ten thousand yuan through calculation.

2) And building projects of house property service buildings in Nanning cities avoid setting up of full framing scaffolds, the steel pipe lease cost of the scaffolds is saved by 8 ten thousand yuan, the setting and dismantling cost is 1 ten thousand yuan, and the scaffold measures are saved by 9 ten thousand yuan in total. The construction period is shortened by 25 days, the machine shift cost of each machine is 0.2 ten thousand yuan, 3 machines are used every day, and the machine shift cost is reduced by 15 ten thousand yuan in total. And obtains better social benefit.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The construction method for externally expanding, splicing and integrally jacking the large-span net rack is characterized by comprising the following steps of:

assembling and jacking: assembling the net rack on the ground, installing a jacking bracket when the net rack is assembled to the position of the stand, and stopping jacking when the net rack is jacked by the jacking bracket to a set height to meet the assembly of the next grid;

2. The large-span net rack outward-expanding splicing integral jacking construction method according to claim 1, characterized in that the construction method comprises the following specific process flows:

s1, preparation before construction;

s2, assembling net racks;

s3, arranging jacking points, and installing a jacking device;

s4, quality and safety inspection;

s5, trial jacking;

s6, formally jacking;

s7, outward expanding assembly and circular lifting;

s8, lifting to the right and butting the support;

s9, synchronous unloading;

and S10, removing the jacking device, and finishing the installation.

3. The large-span net rack externally-expanding, assembling and integral jacking construction method according to claim 2, wherein the preparation before construction in the step S1 is as follows:

s101, counting the net rack materials which have entered the field, respectively stacking balls and rods in a classified manner, and checking the processing sizes of the balls and the rods;

s102, cleaning up sundries stacked on site to ensure smooth construction;

s106, checking the foundation of the jacking equipment, wherein the foundation should have enough strength.

4. The large-span net rack outward-expanding assembling integral jacking construction method according to claim 2, wherein the net rack assembling in the step S2 is as follows:

s201, installing a lower chord plane net rack, and specifically comprising:

s20202, supporting the two diagonal web members on the lower chord ball, and tensioning the upper chord member above to enable the upper chord member to be gradually close to the mounted upper chord ball to be screwed, adjusted and fastened;

5. The large-span net rack outward-expanding assembling integral jacking construction method according to claim 4, wherein the net rack is a steel net rack, and the assembling process of the steel net rack is as follows:

(4) assembling a lower chord member of the next unit grid frame;

(7) and assembling the whole structure.

6. The construction method for the outward-expanding, assembling and integral jacking of the large-span net rack according to claim 2, wherein in the step of determining the position of the jacking device in the step S3, each node ball is uniformly stressed in the jacking process, and a steel plate support is arranged at the bottom of the jacking device;

7. The construction method for the outward-expanding, splicing and integral jacking of the large-span net rack according to claim 1, wherein the formal jacking in the step S6 is as follows:

s604, the lower bracket is stressed when the piston rod is heightened, a section of support frame is added when the piston rod is completely extended out, the piston rod retracts after the related bolt is screwed, the upper bracket is stressed, when the piston rod retracts completely, the lower bracket retracts to a position capable of being stressed, the cross rod is moved upwards, and the position of the cross rod corresponds to that of a stress beam of the lower bracket;

s605, when the upper bracket is stressed during dismantling, the piston rod retracts to be not stressed, the cross rod is moved downwards, the position of the cross rod is corresponding to that of the stress beam of the lower bracket, the piston rod extends out, the lower bracket is moved to the next support frame, the lower bracket is stressed, the upper bracket is not stressed, and a section of support frame is dismantled.

8. The large-span net rack externally-expanding assembling integral jacking construction method according to claim 2, wherein the externally-expanding assembling and cyclic lifting in the step S7 are as follows:

9. The construction method for the outward-expanding, assembling and integral jacking of the large-span net rack according to claim 2, wherein the lifting in place and the butt joint of the support in the step S8 are as follows:

10. The construction method for the outward-expanding, splicing and integral jacking of the large-span net rack according to claim 2, wherein the synchronous unloading in the step S9 is as follows: