Fabricated prestressed fish-belly sill steel trestle for foundation pit construction and mounting method

Abstract

The invention provides an assembly type prestress fish-bellied beam steel trestle for foundation pit construction and an installation method, and relates to the technical field of foundation pit engineering, the section height of the assembly type prestress fish-bellied beam steel trestle is large in the middle and small in the two ends, and the whole assembly type prestress fish-bellied beam steel trestle is of a fish-bellied beam structure. Prestress is applied to the bridge structure through the prestressed steel strands, deflection deformation of the steel trestle is effectively reduced when construction vehicles pass through, and the smoothness of the steel trestle and the vehicle passing ability can be further improved; the steel strand limiter can fix the prestressed steel strand and adjust the direction of the prestressed steel strand, so that the prestressed steel strand can move freely in the longitudinal direction when the steel trestle applies prestress, the force transmission stability between the prestressed steel strand and the steel web member is guaranteed, and the steel strand limiter is high in popularization value.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit engineering, and in particular to an assembled prestressed fish-belly beam steel trestle for foundation pit construction and an installation method thereof. Background Art

[0002] During the construction of foundation pit projects, trestles are often used as important transportation channels for the transportation of waste soil and the supply of materials. Common foundation pit trestles include reinforced concrete trestles, steel trestles, combined trestles and other forms. The construction of reinforced concrete trestles and combined trestles involves the process of pouring concrete. The long curing cycle of concrete seriously affects the rapid construction of the trestles and even the entire support structure. At the same time, as a temporary structure, after the service life of the trestles ends, it is difficult to dismantle the reinforced concrete components, and the materials cannot be reused. In foundation pit projects, the use of steel trestles can avoid the problems of slow construction speed and serious material waste of reinforced concrete trestles and combined trestles. In the existing steel trestle technology, the patent with publication number 202310969023.2 discloses a foundation pit assembled steel trestle and its construction method. The trestle has the advantages of easy installation and disassembly and flexible structural layout, but the trestle is essentially a Bailey beam structure, and it is often necessary to increase the overall height of the structure to meet the requirements of structural stiffness for the passage of heavy vehicles, which has a certain degree of impact on the on-site layout and normal construction of the foundation pit project; the patent with publication number 202310123825.1 discloses a tensioned beam steel trestle for a foundation pit, which uses the reinforced concrete internal support in the foundation pit support structure as the lower structure of the trestle, which is more in line with the actual on-site conditions of general foundation pit projects, and the tensioned beam structure effectively reduces the height of the bridge superstructure, which is more conducive to the layout of the construction site, but the overall stiffness of the tensioned beam structure proposed by the steel trestle is not large, and it is prone to large flexural deformation when the vehicle load is large, affecting the smoothness of the trestle and the passability of the vehicle.

[0003] Therefore, it has become a real need in the field of foundation pit engineering for the applicant to think about how to develop a steel trestle that can improve bridge stiffness by applying prestress, achieve rapid trestle construction through modularization, and achieve efficient reuse of components through assembly. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide an assembled prestressed fish-belly beam steel trestle for foundation pit construction and an installation method. The present invention adopts prestressed steel strands to apply prestress to the bridge structure, effectively reducing the flexural deformation of the steel trestle when construction vehicles pass through, and can further improve the smoothness and vehicle passability of the steel trestle; the steel strand limiter of the present invention can fix the prestressed steel strands and adjust the direction of the prestressed steel strands, so that the prestressed steel strands can move freely in the longitudinal direction when the steel trestle is prestressed, thereby ensuring the force transmission stability between the prestressed steel strands and the steel web rods.

[0005] The present invention is achieved through the following technical solutions:

[0006] An assembled prestressed fish-belly beam steel trestle for foundation pit construction, the cross-section height of which is larger in the middle and smaller at both ends, and the whole is a fish-belly beam structure, which includes an assembled main body mechanism and two groups of symmetrically arranged prestressed mechanisms, and the prestressed mechanisms are arranged on the lower side of the assembled main body mechanism, wherein;

[0007] The assembled main structure includes multiple sets of steel longitudinal beams, steel cross beams and assembled bridge decks. The steel longitudinal beams and steel cross beams are cross-shaped and fixedly connected, and the assembled bridge decks are fixedly laid on the steel longitudinal beams.

[0008] The prestressed mechanism includes multiple groups of support and limit assemblies, prestressed steel strands and two groups of prestressing units. The upper end of the support and limit assemblies is fixedly connected to the steel cross beam, and the length of the support and limit assemblies gradually increases from the edge to the middle of the steel trestle. The lower end of the support and limit assemblies is used to limit and adjust the steel strands. The two groups of prestressing units are respectively arranged at the bridge ends of the steel trestle. The prestressing units are used to lock and apply prestress to the prestressed steel strands.

[0009] It can be seen that in the above technical scheme, the present invention adopts prestressed steel strands to apply prestress to the bridge structure, which effectively reduces the flexural deformation of the steel trestle when construction vehicles pass, and can further improve the smoothness and vehicle passability of the steel trestle; the steel strand limiter of the present invention can fix the prestressed steel strands and adjust the direction of the prestressed steel strands, so that the prestressed steel strands can move freely in the longitudinal direction when the steel trestle is prestressed, thereby ensuring the force transmission stability between the prestressed steel strands and the steel web rods.

[0010] According to the above technical solution, preferably, the support and limit assembly includes a steel web, a longitudinal tie rod, a transverse tie rod and a steel strand limiter, wherein;

[0011] The upper ends of the steel web bars, longitudinal tie rods and transverse tie rods are fixedly connected to the steel cross beams;

[0012] The longitudinal tie rod is arranged in the longitudinal direction, the transverse tie rod is arranged in the transverse direction, and the lower ends of the longitudinal tie rod and the transverse tie rod are fixedly connected to the middle and lower parts of the steel web members;

[0013] The steel strand limiter is arranged at the lower end of the steel web rod, and is used to limit the lateral position of the prestressed steel strand and adjust the movement of the prestressed steel strand along the longitudinal direction.

[0014] It can be seen that in the above technical scheme, the longitudinal tie rods, transverse tie rods and horizontal tie rods of the present invention can improve the stability of the steel web members when the steel trestle is in use, and effectively ensure the coordinated force between the main load-bearing components such as prestressed steel strands, steel web members, steel cross beams and steel longitudinal beams.

[0015] According to the above technical solution, preferably, the steel strand limiter comprises a limiter base, a limiter vertical plate, two sets of steel strand limiter rollers and vertical plate reinforcement ribs, wherein;

[0016] The stopper base is formed by channel steel, and the connection holes reserved on the wing plate of the stopper base are used for fixed connection with the steel web;

[0017] The stopper vertical plate is a trapezoidal steel plate, and a through hole is reserved along its axis for installing the steel strand stopper roller shaft;

[0018] The steel strand limiter roller shaft comprises a concave roller and a rotating shaft, both ends of the rotating shaft are rotatably connected to the limiter vertical plate, and the spacing of the concave rollers is adapted to the prestressed steel strand;

[0019] The prestressed steel strand passes through between the rollers of the steel strand limiter and can move with the rotation of the rollers of the steel strand limiter.

[0020] According to the above technical solution, preferably, the prestressing unit includes a prestressing box, a hollow jack, a steel strand lock, an inner partition and two sets of limiting rollers, wherein;

[0021] The prestressed box is fixedly installed at the lower part of both ends of the steel trestle;

[0022] The inner partition is fixedly arranged in the prestressed box, one end of the hollow jack is against the inner partition, and the steel strand lock is against the other end of the hollow jack;

[0023] The limiting roller is arranged on the inlet side of the prestressed box;

[0024] The prestressed steel strand passes through the limiting roller, the inner partition and the hollow jack in sequence, and is locked with a steel strand lock. The hollow jack pulls the prestressed steel strand to apply prestress.

[0025] According to the above technical solution, preferably, along the transverse direction of the steel trestle, adjacent support limit assemblies are connected by horizontal tie rods, and the steel web members are vertically mounted on the lower wing plates of the steel beams by bolts, wherein;

[0026] The longitudinal tie rod, transverse tie rod and horizontal tie rod are all steel tie rods with O-type joints at both ends and tensioners in the middle;

[0027] After the longitudinal tie rod is tensioned, it is used to improve the stability of the steel web along the longitudinal direction of the steel trestle;

[0028] After the transverse tie rod is tensioned, it is used to improve the stability of the steel web along the transverse direction of the steel trestle;

[0029] The horizontal tie rods are tensioned to improve the lateral stability of the steel trestle.

[0030] According to the above technical solution, preferably, the steel web is cut from an I-beam, and a web connecting plate is welded to the top of the steel web; U-shaped web angle codes, transverse tie rod connecting bolts, and horizontal tie rod connecting bolts are installed on the steel web; and the steel strand limiter is installed on the lower end of the steel web by bolts.

[0031] According to the above technical solution, preferably, it also includes a safety monitoring subsystem, which includes a sensing mechanism, a signal transmitting unit, a signal receiving unit and a digital simulation unit. The sensing mechanism includes a plurality of pressure sensing units arranged on the support limit assembly, the steel longitudinal beam and the steel cross beam. The pressure sensing unit records the three-dimensional coordinate value in real time. The transmitting end is fixedly installed on the assembled main body mechanism, and the transmitting end is connected to the sensing mechanism signal. The digital simulation unit receives the sensing mechanism value monitored in real time by the signal transmitting unit through the signal receiving unit, and realizes analysis and early warning through the built-in algorithm model data.

[0032] It can be seen that in the above technical scheme, the present invention can solve the problem that it is difficult to accurately observe whether the overall assembly, prestressing and hoisting process of the steel trestle are in a stable state by the naked eye. Through high-precision data collection and analysis, it is further analyzed whether the shaking angle of the steel trestle and the relative displacement of each component during the assembly and hoisting process exceed the set threshold, which is convenient for timely suspension of the assembly, prestressing and hoisting process operations, and waiting for the steel trestle to stabilize before continuing the operation, greatly reducing the operation risk; in addition, the deformation degree of the support limit assembly, steel longitudinal beam and steel cross beam during the assembly, prestressing and hoisting process can be analyzed, and the safety hazard caused by excessive deformation of the support limit assembly, steel longitudinal beam and steel cross beam can be effectively prevented.

[0033] According to the above technical solution, preferably, it also includes an assembled auxiliary mechanism, which includes a bridge limiter, an assembled guardrail and a beam end support, wherein;

[0034] Bridge stoppers are installed at both ends of the steel longitudinal beams;

[0035] The assembled guardrails are divided into two groups and installed at both ends of the steel beam;

[0036] The beam end support is installed at the bottom of the steel beam and is used to connect the steel trestle with the concrete support beam in the foundation pit support structure.

[0037] According to the above technical solution, preferably, the assembled bridge deck comprises a patterned steel plate, a deck beam and a deck limit column, wherein;

[0038] The panel beams are welded to the lower surface of the patterned steel plate at equal intervals;

[0039] The panel limit columns are arranged on the lower surface of both ends of the panel beam, and the steel longitudinal beam is preset with slots that are compatible with the panel limit columns.

[0040] The present invention also discloses a method for installing an assembled prestressed fish belly beam steel trestle for foundation pit construction, which is characterized in that the method is used to install the assembled prestressed fish belly beam steel trestle for foundation pit construction, and comprises the following steps:

[0041] Step 1: Connect the steel longitudinal beam and the steel cross beam in a cross-shaped manner with bolts, and install the steel web bars of the support limit assembly under the corresponding steel cross beams with bolts, install the longitudinal tie rods, transverse tie rods and horizontal tie rods in sequence, and rotate the tensioners of the longitudinal tie rods, transverse tie rods and horizontal tie rods to make each tie rod in a tensioned state;

[0042] Step 2: Install a steel strand limiter at the bottom end of the steel web, and install a prestressing unit with a built-in hollow jack on the corresponding steel beam, pass the prestressed steel strands through multiple groups of steel strand limiters located on the same longitudinal section in sequence, and pass both ends of the prestressed steel strands through the limit rollers, inner partitions and hollow jacks in the prestressing unit in sequence, and then install the steel strand lock;

[0043] Step 3: Install the upper support plate of the beam end support on the lower wing plate of the steel cross beam at the head and tail of the steel trestle, and hoist the steel trestle so that the upper support plate of the beam end support is combined with the lower support plate pre-anchored on the concrete support beam;

[0044] Step 4: Drill holes on the lower wing plate of the steel longitudinal beam to install the bridge limiter, install the assembled guardrails in two groups on both sides of the steel trestle with bolts, and lay the assembled bridge deck on the steel longitudinal beam;

[0045] Step 5: Push the installed hollow jack to apply prestress;

[0046] Step 6: After the use of the prefabricated prestressed fish belly beam steel trestle is over, the steel trestle is dismantled in the reverse order of the above steps, and all components are recovered and reused.

[0047] The beneficial effects of the present invention are:

[0048] (1) The present invention uses prestressed steel strands to apply prestress to the bridge structure, effectively reducing the flexural deformation of the steel trestle when construction vehicles pass through, and can further improve the smoothness and vehicle passability of the steel trestle;

[0049] (2) The steel strand limiter of the present invention can fix the prestressed steel strand and adjust the direction of the prestressed steel strand, so that the prestressed steel strand can move freely in the longitudinal direction when the steel trestle is prestressed, thereby ensuring the stability of force transmission between the prestressed steel strand and the steel web;

[0050] (3) The longitudinal tie rods, transverse tie rods and horizontal tie rods of the present invention can improve the stability of the steel web members when the steel trestle is in use, and effectively ensure the coordinated force between the main load-bearing components such as the prestressed steel strands, steel web members, steel cross beams and steel longitudinal beams;

[0051] (4) The main structural components and the auxiliary structural components of the present invention are connected by bolts, which realizes the assembly construction of the entire steel trestle bridge and improves the efficiency of the steel trestle bridge construction;

[0052] (5) The dimensions of the assembled bridge deck and assembled guardrail of the present invention are coordinated with the spacing between the steel longitudinal beams and the steel cross beams, so that the design of the steel trestle structure is standardized, and the bridge deck and guardrail are characterized by simple installation, reliable force bearing, and convenient replacement;

[0053] (6) The main structure and auxiliary structure of the steel trestle of the present invention are easy to disassemble and assemble, and the recycling rate is 100%, which realizes the reuse of the steel trestle; compared with the reinforced concrete trestle and steel trestle used in some foundation pit projects, the present invention provides a steel trestle structure for foundation pit projects with high construction efficiency, easy disassembly and assembly, and 100% reuse of components;

[0054] (7) The present invention can solve the problem that it is difficult to accurately observe whether the overall assembly, prestressing and hoisting process of the steel trestle are in a stable state by the naked eye. Through high-precision data collection and analysis, it can further analyze whether the shaking angle of the steel trestle and the relative displacement of each component during the assembly and hoisting process exceed the set threshold, so as to facilitate timely suspension of the assembly, prestressing and hoisting process operations, and wait for the steel trestle to stabilize before continuing the operation, which greatly reduces the operation risk; in addition, it can analyze the deformation degree of the support limit assembly, steel longitudinal beam and steel cross beam during the assembly, prestressing and hoisting process, and effectively prevent the safety hazard caused by excessive deformation of the support limit assembly, steel longitudinal beam and steel cross beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The main structural diagram of the fish belly beam steel trestle is shown;

[0056] Figure 2 A cross-section of a fish-belly steel trestle is shown;

[0057] Figure 3 The isometric diagram of the steel longitudinal beam, steel cross beam, assembled guardrail and assembled bridge deck in the fish-belly beam steel trestle is shown;

[0058] Figure 4 An isometric schematic diagram of the support and limit assembly and the steel beam connection structure in the fish-belly beam steel trestle is shown;

[0059] Figure 5The isometric schematic diagram of the steel strand stopper and the prestressed steel strand in the fish-belly beam steel trestle is shown;

[0060] Figure 6 An isometric schematic diagram of a steel web and a steel strand stopper in a fish-belly beam steel trestle is shown;

[0061] Figure 7 The isometric schematic diagram of the connection structure between the prestressing unit and the steel cross beam in the fish-belly beam steel trestle is shown;

[0062] Figure 8 Shows Figure 7 A schematic cross-sectional structure diagram of;

[0063] Fig. 9 An isometric view of a fabricated guardrail in a fish-belly beam steel trestle is shown;

[0064] Fig.10 An isometric schematic diagram of a fabricated bridge deck in a fish-belly girder steel trestle is shown;

[0065] Fig.11 An isometric schematic diagram of a bridge stop in a fish-belly girder steel trestle is shown;

[0066] Description of reference numerals:

[0067] 1. Assembled main structure; 2. Prestressed structure; 3. Steel longitudinal beam; 4. Steel cross beam; 5. Assembled bridge deck; 6. Support and limit assembly; 7. Prestressed steel strand; 8. Prestressing unit; 9. Steel web; 10. Longitudinal tie rod; 11. Transverse tie rod; 12. Steel strand limiter; 13. Limiter base; 14. Limiter vertical plate; 15. Steel strand limiter roller; 16. Vertical plate reinforcement rib; 17. Prestressed box; 18. Hollow jack; 19. Steel strand lock; 20. Inner partition; 21. Limit roller; 22. Horizontal pull rod; 23. Prefabricated attachment; 24. Bridge limiter; 25. Prefabricated guardrail; 26. Beam end support; 27. Patterned steel plate; 28. Panel beam; 29. ​​Panel limiter column; 30. Bridge limiter vertical plate; 31. Bridge limiter connecting plate; 32. Bridge limiter rib plate. DETAILED DESCRIPTION

[0068] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and the best embodiment. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the invention.

[0069] In the description of the invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the invention.

[0070] Example 1

[0071] As shown in the figure, this embodiment provides an assembled prestressed fish belly beam steel trestle for foundation pit construction, the cross-sectional height of which is large in the middle and small at both ends, and the whole is a fish belly beam structure, which includes an assembled main body mechanism 1 and two groups of symmetrically arranged prestressed mechanisms 2, and the prestressed mechanisms 2 are arranged on the lower side of the assembled main body mechanism 1, wherein;

[0072] The assembled main structure 1 includes a plurality of steel longitudinal beams 3, steel cross beams 4 and assembled bridge decks 5. The steel longitudinal beams 3 and steel cross beams 4 are fixedly connected in a cross-vertical manner, and the assembled bridge decks 5 are fixedly laid on the steel longitudinal beams 3.

[0073] The prestressed mechanism 2 includes multiple groups of support and limit assemblies 6, prestressed steel strands 7 and two groups of prestress applying units 8. The upper end of the support and limit assemblies 6 is fixedly connected to the steel cross beam 4. The length of the support and limit assemblies 6 gradually increases from the edge to the middle of the steel trestle. The lower end of the support and limit assemblies 6 is used to limit and adjust the steel strands. The two groups of prestress applying units 8 are respectively arranged at the bridge ends of the steel trestle. The prestress applying units 8 are used to lock and apply prestress to the prestressed steel strands 7. The support and limit assemblies 6 include steel webs 9, longitudinal pull rods 10, transverse pull rods 11 and steel strand limiters 12, wherein;

[0074] The upper ends of the steel web members 9, the longitudinal tie rods 10 and the transverse tie rods 11 are fixedly connected to the steel cross beam 4;

[0075] The longitudinal tie rod 10 is arranged in the longitudinal direction, and the transverse tie rod 11 is arranged in the transverse direction. The lower ends of the longitudinal tie rod 10 and the transverse tie rod 11 are fixedly connected to the middle and lower parts of the steel web member 9;

[0076] The steel strand limiter 12 is arranged at the lower end of the steel web 9, and is used to limit the lateral position of the prestressed steel strand 7 and adjust the longitudinal movement of the prestressed steel strand 7; the longitudinal tie rod 10, the transverse tie rod 11, and the horizontal tie rod 22 of the present invention can improve the stability of the steel web 9 when the steel trestle is in use, and effectively ensure the coordinated force between the main load-bearing components such as the prestressed steel strand 7, the steel web 9, the steel cross beam 4, and the steel longitudinal beam 3;

[0077] The steel strand limiter 12 comprises a limiter base 13, a limiter vertical plate 14, two sets of steel strand limiter rollers 15 and vertical plate reinforcing ribs 16, wherein;

[0078] The stopper base 13 is formed by channel steel, and the connection holes reserved on the wing plate of the stopper base 13 are used for fixed connection with the steel web 9;

[0079] The stopper vertical plate 14 is a trapezoidal steel plate, and a through hole is reserved along its axis for installing the steel strand stopper roller 15;

[0080] The steel strand limiter roller shaft 15 comprises a coaxially connected concave roller and a rotating shaft, both ends of the rotating shaft are rotatably connected to the limiter vertical plate 14, and the spacing between the concave rollers is adapted to the prestressed steel strand 7;

[0081] The prestressed steel strand 7 passes through between the steel strand limiter rollers 15 and can move with the rotation of the steel strand limiter rollers 15 .

[0082] The present invention adopts prestressed steel strands 7 to apply prestress to the bridge structure, which effectively reduces the flexural deformation of the steel trestle when construction vehicles pass through, and can further improve the smoothness and vehicle passability of the steel trestle; the steel strand limiter 12 of the present invention can fix the prestressed steel strands 7 and adjust the direction of the prestressed steel strands 7, so that the prestressed steel strands 7 can move freely in the longitudinal direction when the steel trestle is prestressed, thereby ensuring the force transmission stability between the prestressed steel strands 7 and the steel web rods 9.

[0083] Optionally, in a possible implementation, the prestressing unit 8 includes a prestressing box 17, a hollow jack 18, a steel strand lock 19, an inner partition 20 and two sets of limiting rollers 21, wherein;

[0084] The prestressed box 17 is fixedly installed at the lower part of both ends of the steel trestle;

[0085] The inner partition 20 is fixedly arranged in the prestressed box 17, one end of the hollow jack 18 is against the inner partition 20, and the steel strand lock 19 is against the other end of the hollow jack 18;

[0086] The limiting roller shaft 21 is arranged on the inlet side of the prestressed box 17;

[0087] The prestressed steel strand 7 passes through the limiting roller 21, the inner partition 20 and the hollow jack 18 in sequence, and is locked by the steel strand lock 19. The hollow jack 18 pulls the prestressed steel strand 7 to apply prestress.

[0088] Optionally, in a possible implementation, along the transverse direction of the steel trestle, adjacent support limit assemblies 6 are connected by horizontal tie rods 22, and steel web members 9 are vertically mounted on the lower wing plate of the steel beam 4 by bolts, wherein;

[0089] The longitudinal tie rod 10, the transverse tie rod 11, and the horizontal tie rod 22 are all steel tie rods with O-type joints at both ends and a tensioner in the middle;

[0090] The longitudinal tie rod 10 is used to improve the stability of the steel web member 9 along the longitudinal direction of the steel trestle after being tensioned;

[0091] After the transverse tie rod 11 is tensioned, it is used to improve the stability of the steel web member 9 along the transverse direction of the steel trestle;

[0092] The horizontal tie rod 22 is used to improve the lateral stability of the steel trestle after being tensioned.

[0093] Optionally, in a possible embodiment, the steel web 9 is cut from an I-beam, and a web connecting plate is welded to the top of the steel web 9; a U-shaped web angle code, a transverse tie rod 11 connecting bolts, and a horizontal tie rod 22 connecting bolts are installed on the steel web 9; and a steel strand limiter 12 is installed on the lower end of the steel web 9 by bolts.

[0094] Optionally, in a possible implementation, it further includes an assembled auxiliary mechanism 23, the assembled auxiliary mechanism 23 includes a bridge limiter 24, an assembled guardrail 25 and a beam end support 26, wherein;

[0095] The bridge limiters 24 are installed at both ends of the steel longitudinal beam 3;

[0096] The assembled guardrail 25 is divided into two groups and installed at both ends of the steel beam 4;

[0097] The beam end support 26 is installed at the bottom of the steel cross beam 4 and is used to connect the steel trestle with the concrete support beam in the foundation pit support structure.

[0098] Optionally, in a possible implementation, the assembled bridge deck 5 includes a patterned steel plate 27, a deck beam 28 and a deck limiting column 29, wherein;

[0099] The panel beams 28 are welded to the lower surface of the patterned steel plate 27 at equal intervals;

[0100] The panel limiting columns 29 are arranged on the lower surfaces of both ends of the panel beam 28 , and the steel longitudinal beam 3 is pre-set with slots adapted to the panel limiting columns 29 .

[0101] Optionally, in a possible embodiment, the bridge limiter 24 includes a bridge limiter upright plate 30, a bridge limiter connecting plate 31 and a bridge limiter rib plate 32. The bridge limiter upright plate 30 is a rectangular steel plate, and its height is greater than the sum of the heights of the steel cross beam 4 and the beam end support 26; the bridge limiter connecting plate 31 is a rectangular steel plate with holes, and its length is consistent with the length of the bridge limiter upright plate 30, and the 8 connecting holes reserved thereon are used for connecting the bridge limiter 24 with the steel longitudinal beam 3; the bridge limiter rib plate 32 is a right-angled trapezoidal steel plate, and its height is consistent with the height of the bridge limiter upright plate 30, and its upper and lower width is the same as the bridge limiter connecting plate The width of 31 is consistent; after the bridge limiter upright plate 30 and the bridge limiter connecting plate 31 are welded vertically to each other into an L shape, the right-angle waist of the bridge limiter rib plate 32 is welded to the bridge limiter upright plate 30, and the upper bottom is welded to the bridge limiter connecting plate 31 to improve the connection strength and rigidity between the bridge limiter upright plate 30 and the bridge limiter connecting plate 31; the welded bridge limiter 24 is respectively installed on the lower wing plates of the 1st, 3rd, 4th and 6th steel longitudinal beams 3 by bolts, and the position is located between the two steel cross beams 4 at the ends of the steel longitudinal beams 3, and the bridge limiter upright plate 30 should face the concrete support beam, and there should be a certain gap between the two.

[0102] Example 2

[0103] This embodiment includes all the technical features of embodiment 1, and also includes a safety monitoring subsystem. The safety monitoring subsystem includes a sensing mechanism, a signal transmitting unit, a signal receiving unit and a digital simulation unit. The sensing mechanism includes a plurality of pressure sensing units arranged on the support limit assembly 6, the steel longitudinal beam 3 and the steel cross beam 4. The pressure sensing unit records the three-dimensional coordinate values ​​in real time. The transmitting end is fixedly mounted on the assembled main body mechanism 1, and the transmitting end is connected to the sensing mechanism signal. The digital simulation unit receives the sensing mechanism value monitored in real time by the signal transmitting unit through the signal receiving unit, and realizes analysis and early warning through the built-in algorithm model data. The present invention can solve the existing manual single It is difficult to accurately observe with the naked eye whether the overall assembly, prestressing and hoisting process of the steel trestle are in a stable state. Through high-precision data collection and analysis, it is further analyzed whether the shaking angle of the steel trestle and the relative displacement of each component during the assembly and hoisting process exceed the set threshold, so as to facilitate timely suspension of the assembly, prestressing and hoisting process operations, and wait for the steel trestle to stabilize before continuing the operation, which greatly reduces the operation risk; in addition, the deformation degree of the support limit assembly 6, steel longitudinal beam 3 and steel cross beam 4 during the assembly, prestressing and hoisting process can be analyzed to effectively prevent the safety hazards caused by excessive deformation of the support limit assembly 6, steel longitudinal beam 3 and steel cross beam 4.

[0104] Example 3

[0105] This embodiment discloses an installation method of an assembled prestressed fish belly beam steel trestle for foundation pit construction, which is used to install the assembled prestressed fish belly beam steel trestle for foundation pit construction of the above embodiment 1, and includes the following steps:

[0106] Step 1, connect the steel longitudinal beam 3 and the steel cross beam 4 into one body by bolts in a cross form, and install the steel web rod 9 of the support limit assembly 6 under the corresponding steel cross beam 4 by bolts, install the longitudinal tie rod 10, the transverse tie rod 11 and the horizontal tie rod 22 in sequence, and rotate the tensioners of the longitudinal tie rod 10, the transverse tie rod 11 and the horizontal tie rod 22 to make each tie rod in a tensioned state;

[0107] Step 2, install a steel strand stopper 12 at the bottom end of the steel web 9, and install a prestressing unit 8 with a built-in hollow jack 18 on the corresponding steel beam 4, pass the prestressed steel strand 7 through multiple groups of steel strand stoppers 12 located on the same longitudinal section in sequence, and pass both ends of the prestressed steel strand through the limiting roller 21, the inner partition 20 and the hollow jack 18 in the prestressing unit 8 in sequence, and then install the steel strand lock 19;

[0108] Step 3, installing the upper support plate of the beam end support 26 on the lower wing plate of the steel cross beam 4 at the head and tail of the steel trestle, and hoisting the steel trestle so that the upper support plate of the beam end support 26 is combined with the lower support plate pre-anchored on the concrete support beam;

[0109] Step 4: Drill holes on the lower wing plate of the steel longitudinal beam 3 to install the bridge stopper 24, install the bolted assembled guardrail 25 in two groups on both sides of the steel trestle, and lay the assembled bridge deck 5 on the steel longitudinal beam 3;

[0110] Step 5: Push the installed hollow jack 18 to achieve the application of prestress;

[0111] Step 6: After the use of the prefabricated prestressed fish belly beam steel trestle is over, the steel trestle is dismantled in the reverse order of the above steps, and all components are recovered and reused.

[0112] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An assembled prestressed fish belly beam steel trestle for foundation pit construction, characterized in that: Its cross-sectional height is large in the middle and small at both ends, and the whole is a fish belly beam structure, which includes an assembled main body structure and two groups of symmetrically arranged prestressed mechanisms, wherein the prestressed mechanisms are arranged on the lower side of the assembled main body structure; The assembled main structure includes multiple groups of steel longitudinal beams, steel cross beams and assembled bridge decks, the steel longitudinal beams and steel cross beams are cross-vertically fixedly connected, and the assembled bridge deck is fixedly laid on the steel longitudinal beams; The prestressed mechanism includes multiple groups of support and limit assemblies, prestressed steel strands and two groups of prestressing units. The upper ends of the support and limit assemblies are fixedly connected to the steel cross beams. The length of the support and limit assemblies gradually increases from the edge to the middle of the steel trestle. The lower ends of the support and limit assemblies are used to limit and adjust the steel strands. The two groups of prestressing units are respectively arranged at the bridge ends of the steel trestle. The prestressing units are used to lock and apply prestress to the prestressed steel strands.

2. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 1 is characterized in that: The support and limit assembly includes a steel web, a longitudinal tie rod, a transverse tie rod and a steel strand limiter, wherein; The upper ends of the steel web bars, longitudinal tie rods and transverse tie rods are fixedly connected to the steel cross beam; The longitudinal tie rod is arranged in the longitudinal direction, the transverse tie rod is arranged in the transverse direction, and the lower ends of the longitudinal tie rod and the transverse tie rod are fixedly connected to the middle and lower parts of the steel web bars; The steel strand limiter is arranged at the lower end of the steel web, and is used to limit the lateral position of the prestressed steel strand and adjust the movement of the prestressed steel strand in the longitudinal direction.

3. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 2 is characterized in that: The steel strand limiter comprises a limiter base, a limiter vertical plate, two sets of steel strand limiter rollers and vertical plate reinforcing ribs, wherein; The stopper base is formed by processing channel steel, and the connection holes reserved on the wing plate of the stopper base are used for fixed connection with the steel web; The stopper vertical plate is a trapezoidal steel plate, and a through hole for installing the steel strand stopper roller is reserved along its axis; The steel strand limiter roller shaft comprises a concave roller and a rotating shaft, both ends of the rotating shaft are rotatably connected to the limiter vertical plate, and the spacing of the concave rollers is adapted to the prestressed steel strand; The prestressed steel strand passes through between the roller shafts of the steel strand limiter and can move along with the rotation of the roller shafts of the steel strand limiter.

4. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 1 is characterized in that: The prestressing unit comprises a prestressing box, a hollow jack, a steel strand lock, an inner partition and two sets of limiting rollers, wherein; The prestressed box is fixedly installed at the lower part of both ends of the steel trestle; The inner partition is fixedly arranged in the prestressed box, one end of the hollow jack is against the inner partition, and the steel strand lock is against the other end of the hollow jack; The limiting roller is arranged at the inlet side of the prestressed box; The prestressed steel strand passes through the limiting roller, the inner partition and the hollow jack in sequence, and is locked by a steel strand lock. The hollow jack pulls the prestressed steel strand to apply prestress.

5. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 2, characterized in that: Along the transverse direction of the steel trestle, adjacent support limit assemblies are connected by horizontal tie rods, and the steel web members are vertically mounted on the lower wing plates of the steel cross beams by bolts, wherein; The longitudinal tie rods, transverse tie rods and horizontal tie rods are all steel tie rods with O-type joints at both ends and tensioners in the middle; After the longitudinal tie rod is tensioned, it is used to improve the stability of the steel web along the longitudinal direction of the steel trestle; After the transverse tie rod is tensioned, it is used to improve the stability of the steel web along the transverse direction of the steel trestle; The horizontal tie rod is used to improve the lateral stability of the steel trestle after being tensioned.

6. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 5, characterized in that: The steel web is cut from an I-beam, and a web connecting plate is welded to the top of the steel web; a U-shaped web angle code, a transverse tie rod connecting bolt, and a horizontal tie rod connecting bolt are installed on the steel web; the steel strand limiter is installed on the lower end of the steel web by bolts.

7. The prefabricated prestressed fish belly beam steel trestle for foundation pit construction according to claim 1, characterized in that: It also includes a safety monitoring subsystem, which includes a sensing mechanism, a signal transmitting unit, a signal receiving unit and a digital simulation unit. The sensing mechanism includes a plurality of pressure sensing units arranged on support limit assemblies, steel longitudinal beams and steel cross beams. The pressure sensing units record three-dimensional coordinate values ​​in real time. The transmitting end is fixedly mounted on the assembled main body mechanism, and the transmitting end is connected to the sensing mechanism signal. The digital simulation unit receives the sensing mechanism value monitored in real time by the signal transmitting unit through the signal receiving unit, and realizes analysis and early warning through the built-in algorithm model data.

8. The prefabricated prestressed fish belly beam steel trestle for foundation pit construction according to claim 1, characterized in that: It also includes assembled auxiliary mechanisms, which include bridge limiters, assembled guardrails and beam end supports, wherein; The bridge limiters are installed at both ends of the steel longitudinal beam; The assembled guardrails are divided into two groups and installed at both ends of the steel beam respectively; The beam end support is installed at the bottom of the steel cross beam and is used for connecting the steel trestle with the concrete support beam in the foundation pit support structure.

9. The prestressed fish belly beam steel trestle for foundation pit construction according to claim 1, characterized in that: The assembled bridge deck comprises a patterned steel plate, a deck beam and a deck limit column, wherein; The panel beams are welded to the lower surface of the patterned steel plate at equal intervals; The panel limiting columns are arranged on the lower surfaces of both ends of the panel beam, and the steel longitudinal beam is pre-set with a slot adapted to the panel limiting columns.

10. A method for installing an assembled prestressed fish belly beam steel trestle for foundation pit construction, characterized in that: The method for installing the prestressed fish belly beam steel trestle for foundation pit construction according to claim 1 comprises the following steps: Step 1: Connect the steel longitudinal beam and the steel cross beam in a cross-shaped manner with bolts, and install the steel web bars of the support limit assembly under the corresponding steel cross beams with bolts, install the longitudinal tie rods, transverse tie rods and horizontal tie rods in sequence, and rotate the tensioners of the longitudinal tie rods, transverse tie rods and horizontal tie rods to make each tie rod in a tensioned state; Step 2: Install a steel strand limiter at the bottom end of the steel web, and install a prestressing unit with a built-in hollow jack on the corresponding steel beam, pass the prestressed steel strands through multiple groups of steel strand limiters located on the same longitudinal section in sequence, and pass both ends of the prestressed steel strands through the limit rollers, inner partitions and hollow jacks in the prestressing unit in sequence, and then install the steel strand lock; Step 3: Install the upper support plate of the beam end support on the lower wing plate of the steel cross beam at the head and tail of the steel trestle, and hoist the steel trestle so that the upper support plate of the beam end support is combined with the lower support plate pre-anchored on the concrete support beam; Step 4: Drill holes on the lower wing plate of the steel longitudinal beam to install the bridge limiter, install the assembled guardrails in two groups on both sides of the steel trestle with bolts, and lay the assembled bridge deck on the steel longitudinal beam; Step 5: Push the installed hollow jack to apply prestress; Step 6: After the use of the prefabricated prestressed fish belly beam steel trestle is over, the steel trestle is dismantled in the reverse order of the above steps, and all components are recovered and reused.

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