Concreting of Super-large Foundation Slab in Deep Foundation Pit with Large-diameter and Ultra-long Chute Pipe in Narrow Space and Construction Method

Abstract

The present invention relates to a method for pouring an extra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space, which includes the following steps: a middle tie rod and a top tie rod are arranged between the telescopic vertical rods of a standardized steel support; a slide rail installed on the top tie rod is connected to the standardized steel support; a bifurcated box is installed on the top of the standardized steel support through a bifurcated box fixing system; and the foundation pit floor slab is poured. The beneficial effects of the present invention are as follows: By adopting the standardized steel support technology, a chute is arranged on the support cross bar of the standardized steel support. By adjusting the internal threaded rod and installing a fastening nut to tighten the slider in the chute, and setting a U-shaped limiting piece, the limiting block is placed in the limiting groove arranged on the middle tie rod, so as to quickly position the tie rod and form a steel support with stable structure.

Description

Technical Field

[0001] The present invention belongs to the field of deep foundation pit bottom slab construction, and particularly relates to a method for pouring an extra-large bottom slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space and a construction method thereof. Background Art

[0002] With the advancement of the urbanization process, more and more high-rise and super high-rise buildings are constructed in the city centers. The foundations of these high-rise and super high-rise buildings in the downtown areas mostly adopt pile raft foundations buried in deep foundation pits. The construction of mass concrete for the bottom slab in the deep foundation pit often faces the following problems: small construction site around the foundation pit, difficult traffic organization and coordination, tight construction period, high requirements for safety and civilization, long continuous pouring time of concrete, and easy occurrence of construction cold joints resulting in bottom slab leakage. Rapid pouring of mass concrete for the raft in the deep foundation pit is the key to controlling the construction quality of super high-rise buildings, and also the key to reducing the risk of foundation pit heave, reducing deformation, and ensuring the safety of the foundation pit.

[0003] For the mass concrete of the raft in the deep foundation pit, the commonly used pouring methods include pumping with a ground pump or a truck pump, and pouring with a suspension tank. These methods have low pouring efficiency of pumped concrete, consume energy, generate noise, and often occur pipe blockage and pipe explosion phenomena. Pouring with a pump truck requires sufficient pump station positions on the edge of the foundation pit, and it is difficult to organize traffic in a narrow site. Pouring with a ground pump involves a large amount of installation and disassembly work of pump pipes, and it is difficult to handle once the pipe is blocked. In summary, it is very meaningful to seek a construction method for pouring an extra-large bottom slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space, which has high construction efficiency, low construction cost, and convenient operation. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for pouring an extra-large bottom slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space and a construction method thereof.

[0005] The construction method for pouring an extra-large bottom slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space includes the following steps:

[0006] Step 1: A middle tie rod and a top tie rod are arranged between the telescopic vertical rods of the standardized steel support; a slider is arranged inside the support cross bar, and a support diagonal rod is arranged between the slider and the middle tie rod;

[0007] Step 2: The standardized steel support is connected to the slide rail installed on the top tie rod; a prefabricated support section is arranged between the external square frame and the internal square frame;

[0008] Step 3: The bifurcation box is installed on the top of the standardized steel support through the bifurcation box fixing system;

[0009] Step 4: The adjacent bifurcation boxes are connected by a chute pipe, the bottom of the bifurcation box is connected to a concrete collection tank, and the concrete collection tank is connected to a mobile branch chute; the bottom slab of the foundation pit is poured.

[0010] Preferably, in step one, the standardized steel bearing includes a telescopic vertical rod, a supporting crossbar, a bottom plate, a U-shaped limiting member, and an external threaded rod. Docking columns are provided at the four corners of the bottom plate. The bottom of the telescopic vertical rod is installed with a docking block and placed inside the docking columns provided on the bottom plate. A top tie rod and a middle tie rod are arranged between the telescopic vertical rods. The supporting crossbar is fixed to the telescopic vertical rod. A chute is formed by grooving in the middle of the supporting crossbar. A slider is provided in the chute. The slider is connected with a supporting diagonal rod, and the other end of the supporting diagonal rod is connected to the telescopic vertical rod.

[0011] Preferably, in step one, an internal threaded rod is installed inside the external threaded rod. By adjusting the internal threaded rod and installing a fastening nut to tighten the slider. A pair of arc-shaped connecting plates are welded to the end of the slider. The arc-shaped connecting plates are connected to the supporting diagonal rod through bearings. A number of bearing rods installed with pyramid cones are evenly arranged at the bottom of the supporting crossbar. The limiting block installed at the end of the U-shaped limiting member is placed in the limiting grooves provided at both ends of the middle tie rod, and the middle tie rod is fixed using a connecting screw.

[0012] Preferably, in step two, the standardized steel support includes an external square frame, an internal square frame, and prefabricated support segments. A shelving bottom plate is arranged between the external square frame and the internal square frame. The prefabricated support segments of the standardized steel support are placed above the shelving bottom plate between the external square frame and the internal square frame. The prefabricated supports of different segments are quickly fixed by inserting the insertion blocks into the threaded jacks, and are further fixed by installing bolts on the docking plates. At the same time, a diagonal brace is provided on the prefabricated support segments to enhance the stability of the structure.

[0013] Preferably, in step two, connecting short rods are provided on both sides of the external square frame. A slide rail is vertically provided on the inner side of the top tie rod. The sliding blocks installed on the connecting short rods of the external square frame are placed inside the slide rails installed on the top tie rod. A bearing plate is provided at the bottom of the slide rail. A jack is installed on the bearing plate and docked with the bottom sliding block. Internal tie rods are installed between adjacent sliding blocks to form an integral structure. By changing the position of the sliding blocks through the jacks, the vertical positions of the external square frame and the internal square frame are adjusted.

[0014] Preferably, in step three, the bifurcated box fixing system includes an adjustable fastening component and a trapezoidal fastener. The adjustable fastening component is installed on the top of the standardized steel support. The adjustable fastening component includes a side short plate and a side long plate. A telescopic bottom plate is installed between the side short plate and the side long plate. The adjustable fastening component makes the side short plate tighten the bifurcated box through a top tightening screw. Trapezoidal fasteners are installed on the other two sides of the standardized steel support. One end of the trapezoidal fastener is welded to the top tie rod, and the other end is welded to a trapezoidal fixing block and connected to the standardized steel support. A number of connecting short columns are evenly arranged between adjacent trapezoidal fasteners. A jack is installed inside the trapezoidal fastener to further fix the bifurcated box. A positioning groove is provided on the top tie rod and fixed corresponding to the positioning block installed at the bottom of the bifurcated box.

[0015] Preferably, in step four, the chutes between adjacent bifurcated boxes are connected to each other through bifurcated holes and form a certain inclination angle. A vertical chute is arranged at the bottom of the bifurcated box and connected to the chute. A concrete collection trough is installed at the bottom of the standardized steel support to collect the concrete flowing out of the vertical chute. Diagonal chutes are arranged on four sides of the concrete collection trough and connected to the mobile branch chute. The mobile branch chute includes an arc-shaped telescopic chute. A number of triangular support frames are installed at the bottom of the arc-shaped telescopic chute, and telescopic cylinders are installed on the triangular support frames to fix the arc-shaped telescopic chute. During the pouring of the foundation pit floor slab, the length of the arc-shaped telescopic chute is changed by adjusting the telescopic cylinder, so as to change the concrete outflow position.

[0016] The super-large foundation pit floor slab with a large-diameter and extra-long chute in a narrow space is poured by any of the above methods.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1) The present invention adopts the standardized steel support technology. A chute is arranged on the support cross bar of the standardized steel support. By adjusting the internal threaded rod and installing a fastening nut to tighten the slider in the chute, and setting a U-shaped limiting part, the limiting block is placed in the limiting groove arranged on the middle tie rod to quickly position the tie rod and form a steel support with stable structure.

[0019] 2) The present invention adopts the rapid assembly technology of the standardized steel support. The standardized steel support is arranged in the laying bottom plate arranged between the external square frame and the internal square frame. By changing the position of the sliding block through a jack, the vertical positions of the external square frame and the internal square frame are adjusted, so as to achieve the purpose of finely adjusting the elevation of the steel support. The prefabricated supports of different segments are quickly fixed by inserting the insertion block into the threaded jack hole, and are further fixed by installing bolts on the docking plate, improving the assembly efficiency of the steel support.

[0020] 3) The present invention adopts the rapid fixing technology of the bifurcated box. By adjusting the jacking screw of the adjustable fastening component, the side short plate is tightened against the bifurcated box, and the bifurcated box is further fixed by installing a jack in the trapezoidal fastener, achieving the purpose of quickly fixing the bifurcated box.

[0021] 4) The present invention adopts the mobile chute inclined groove pouring technology. The mobile branch chute is composed of an arc-shaped telescopic chute. Triangular support frames are installed at its bottom, and telescopic cylinders are installed on the triangular support frames at its end to fix the arc-shaped telescopic chute. During the pouring of the foundation pit floor slab, the length of the arc-shaped telescopic chute is changed by adjusting the telescopic cylinder, so as to change the concrete outflow position and meet the construction requirements. Description of the Drawings

[0022] Figure 1 It is a construction schematic diagram of pouring a super-large foundation pit floor slab with a large-diameter and extra-long chute in a narrow space;

[0023] Figure 2 It is a structural schematic diagram of a standardized steel support

[0024] Figure 3 It is a cross-sectional view of the support cross bar

[0025] Figure 4 It is a structural schematic diagram of a U-shaped limit part

[0026] Figure 5 It is a structural schematic diagram after the installation of the standardized steel support is completed

[0027] Figure 6 It is a structural schematic diagram of the standardized steel support when the steel support is not installed

[0028] Figure 7 It is a connection schematic diagram of the external square frame and the slide rail

[0029] Figure 8 It is a structural schematic diagram of the prefabricated support segment when it is not assembled

[0030] Figure 9 It is a structural schematic diagram of the prefabricated support segment after assembly

[0031] Figure 10 It is a structural schematic diagram after the installation of the bifurcated box

[0032] Figure 11 It is a structural schematic diagram of the standardized steel support when the bifurcated box is not installed

[0033] Figure 12 It is a structural schematic diagram of the adjustable fastening assembly

[0034] Figure 13 It is a structural schematic diagram of the pouring of the mobile chute

[0035] Figure 14 is Figure 13 An enlarged schematic diagram of part A in

[0036] Description of reference numerals: 1 - standardized steel support, 2 - movable branch chute, 3 - standardized steel support bracket, 4 - bifurcated box fixing system, 5 - chute pipe, 6 - bottom plate, 7 - pyramid, 8 - bearing rod, 9 - support cross bar, 10 - support diagonal rod, 11 - telescopic vertical rod, 12 - top connecting rod, 13 - middle connecting rod, 14 - U-shaped limit piece, 15 - limit groove, 16 - bearing, 17 - chute, 18 - docking block, 19 - docking column, 20 - internal threaded rod, 21 - external threaded rod, 22 - arc-shaped connecting plate, 23 - slider, 24 - fastening nut, 25 - limit block, 26 - U-shaped plate, 27 - through hole, 28 - resting bottom plate, 29 - sliding block, 30 - external square frame, 31 - internal square frame, 32 - connecting short rod, 33 - slide rail, 34 - bearing plate, 35 - jack, 36 - internal connecting rod, 37 - prefabricated support segment, 38 - docking plate, 39 - threaded socket, 40 - plug block, 41 - diagonal brace, 42 - trapezoidal fixing block, 43 - adjustable fastening assembly, 44 - connecting short column, 45 - bifurcated box, 46 - bifurcated hole, 47 - trapezoidal fastener, 48 - positioning groove, 49 - telescopic bottom plate, 50 - side short plate, 51 - side long plate, 52 - tightening screw rod, 53 - foundation pit bottom plate, 54 - concrete collection tank, 55 - vertical chute pipe, 56 - inclined chute pipe, 57 - triangular support frame, 58 - telescopic cylinder, 59 - arc-shaped telescopic chute. Detailed implementation manners

[0037] The present invention will be further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the technical field, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0038] Embodiment 1

[0039] As an embodiment, a construction method for pouring an extra-large bottom plate of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space includes the following steps:

[0040] Step 1: Installation of the standardized steel support: A middle connecting rod 13 and a top connecting rod 12 are arranged between the telescopic vertical rods 11 of the standardized steel support 1; a slider 23 is arranged inside the support cross bar 9, and a support diagonal rod 10 is arranged between the slider 23 and the middle connecting rod 13.

[0041] Step 2. Installation of standardized steel formwork support: The sliding blocks 29 installed on the connecting short rods 32 of the external square frame 30 are placed in the slide rails 33 installed on the top connecting rod 12; a bearing plate 34 is provided at the bottom of the slide rail 33, and a jack 35 is installed thereon to butt against the bottom sliding block 29; internal connecting rods 36 are installed between adjacent sliding blocks 29 to form an integral structure; the position of the sliding block 29 is changed by the jack 35, so as to adjust the vertical positions of the external square frame 30 and the internal square frame 31; the prefabricated support segments 37 of the standardized steel formwork support 3 are placed in the laying bottom plates 28 arranged between the external square frame 30 and the internal square frame 31. The prefabricated supports of different segments are quickly fixed by inserting the insertion blocks 40 into the threaded jacks 39, and are further fixed by installing bolts on the docking plates 38. At the same time, diagonal braces 41 are provided on the prefabricated support segments 37 to strengthen the stability of the structure.

[0042] Step 3. Installation of the bifurcated box: In the bifurcated box fixing system 4, the adjustable fastening assembly 43 is installed on the top of the standardized steel formwork support 3. An expansion bottom plate 49 is installed between the side short plate 50 and the side long plate 51 on its side, and the side short plate 50 is tightened against the bifurcated box 45 by adjusting the top tightening screw 52; the trapezoidal fasteners 47 are installed on the other two sides of the standardized steel formwork support 3. One end of it is welded to the top connecting rod 12, and the other end is welded to the trapezoidal fixing block 42 to connect with the standardized steel formwork support 3; a number of connecting short columns 44 are evenly arranged between adjacent trapezoidal fasteners 47, and jacks 35 are installed inside them to further fix the bifurcated box 45; positioning grooves 48 are provided on the top connecting rod 12 and are fixedly installed corresponding to the positioning blocks installed at the bottom of the bifurcated box 45.

[0043] Step 4. Installation of the chute pipe and the mobile branch chute: The chute pipes 5 between adjacent bifurcated boxes 45 are connected to each other through the bifurcated holes 46 and form a certain inclination angle. A vertical chute pipe 55 is provided at the bottom of the bifurcated box 45 and is connected to the chute pipe 5; a concrete collection tank 54 is installed at the bottom of the standardized steel formwork support 3 to collect the concrete flowing out of the vertical chute pipe 55. Diagonal chute pipes 56 are provided on the four sides of the collection tank and are connected to the mobile branch chute 2; the mobile branch chute 2 is composed of an arc-shaped telescopic chute 59. A number of triangular support frames 57 are installed at its bottom, and a telescopic cylinder 58 is installed on the triangular support frame 57 at its end to fix the arc-shaped telescopic chute 59; when the foundation pit bottom plate 53 is poured, the length of the arc-shaped telescopic chute 59 is changed by adjusting the telescopic cylinder 58, so as to change the concrete outflow position to meet the construction requirements.

[0044] Concrete pouring and curing of the bottom plate: The bottom plate concrete is poured at one time according to the construction requirements. After pouring, it is sprinkled with water for curing in time. After the chute pipe system is used up, it is removed and cleaned in time for later use.

[0045] Embodiment 2

[0046] As another embodiment, this second embodiment is proposed based on the first embodiment. A more specific construction method for pouring an extra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space:

[0047] As Figure 2 shown, the standardized steel support 1 includes telescopic vertical rods 11, support crossbars 9, a bottom plate 6, U-shaped limiters 14, and external threaded rods 21. Docking columns 19 are provided at the four corners of the bottom plate 6. The bottom of the telescopic vertical rod 11 is installed with a docking block 18 and placed inside the docking column 19 provided on the bottom plate 6; a top connecting rod 12 and a middle connecting rod 13 are arranged between the telescopic vertical rods 11; the support crossbar 9 is fixed to the telescopic vertical rod 11. A chute 17 is formed by grooving in the middle of the support crossbar 9. A slider 23 is provided in the chute 17. One end of a support diagonal rod 10 is connected to the slider 23, and the other end of the support diagonal rod 10 is connected to the telescopic vertical rod 11.

[0048] As Figure 3 shown, an internal threaded rod 20 is installed inside the external threaded rod 21. By adjusting the internal threaded rod 20 and installing a fastening nut 24, the slider 23 is tightened; a pair of arc-shaped connecting plates 22 are welded to the end of the slider 23. The arc-shaped connecting plates 22 are connected to the support diagonal rod 10 through bearings 16; a number of pressure-bearing rods 8 installed with corner cones 7 are evenly arranged at the bottom of the support crossbar 9; the limit block 25 installed at the end of the U-shaped limiter 14 is placed in the limit grooves 15 provided at both ends of the middle connecting rod 13, and the middle connecting rod 13 is fixed quickly by using a connecting screw.

[0049] Specifically, in step one: The docking block 18 installed at the bottom of the telescopic vertical rod 11 of the standardized steel support 1 is placed inside the docking column 19 provided on the bottom plate 6; a top connecting rod 12 is arranged at the top of the telescopic vertical rod 11; the support crossbar 9 is fixed to the telescopic vertical rod 11, and the slider 23 is placed in the chute 17 formed by grooving in the middle of the support crossbar 9; an internal threaded rod 20 is installed inside the external threaded rod 21. By adjusting the internal threaded rod 20 and installing a fastening nut 24, the slider 23 is tightened; a pair of arc-shaped connecting plates 22 are welded to the end of the slider 23 and fixed to the support diagonal rod 10 through bearings 16; a number of pressure-bearing rods 8 installed with corner cones 7 are evenly arranged at the bottom of the support crossbar 9 to stabilize the support structure; the limit block 25 installed at the end of the U-shaped limiter 14 is placed in the limit grooves 15 provided at both ends of the middle connecting rod 13, and the connecting screw passes through the through hole 27 to quickly position and fix the middle connecting rod 13.

[0050] In step two, as Figure 8 and Figure 9As shown in the figure, the standardized steel support 3 includes an external square frame 30, an internal square frame 31, and a prefabricated support segment 37. A shelving bottom plate 28 is arranged between the external square frame 30 and the internal square frame 31. The prefabricated support segment 37 of the standardized steel support 3 is placed above the shelving bottom plate 28 between the external square frame 30 and the internal square frame 31. The prefabricated supports of different segments are quickly fixed by inserting the insertion block 40 into the threaded jack hole 39, and further fixed by installing bolts on the docking plate 38. At the same time, diagonal braces 41 are arranged on the prefabricated support segment 37 to strengthen the stability of the structure.

[0051] On both sides of the external square frame 30, there are connecting short rods 32. Vertically inside the top connecting rod 12, there is a slide rail 33. The sliding block 29 installed on the connecting short rod 32 of the external square frame 30 is placed inside the slide rail 33 installed on the top connecting rod 12; a bearing pressure plate 34 is arranged at the bottom of the slide rail 33, and a jack 35 is installed on the bearing pressure plate 34 to dock with the bottom sliding block 29; internal connecting rods 36 are installed between adjacent sliding blocks 29 to form an integral structure; by changing the position of the sliding block 29 through the jack 35, the vertical positions of the external square frame 30 and the internal square frame 31 are adjusted.

[0052] It should be noted that the same or similar parts in this embodiment and Embodiment 1 can be referred to each other, and will not be elaborated in this application.

[0053] Embodiment 3

[0054] As another embodiment, this Embodiment 3 is proposed on the basis of Embodiment 2. A more specific construction method for pouring an extra-large bottom plate of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space:

[0055] In Step 3, as Figures 10 to 12 shown, the bifurcated box fixing system 4 includes an adjustable fastening component 43 and a trapezoidal fastener 47. The adjustable fastening component 43 is installed on the top of the standardized steel support 3. The adjustable fastening component 43 includes a side short plate 50 and a side long plate 51. A telescopic bottom plate 49 is installed between the side short plate 50 and the side long plate 51. The adjustable fastening component 43 makes the side short plate 50 press tightly against the bifurcated box 45 through the top tightening screw 52; trapezoidal fasteners 47 are installed on the other two sides of the standardized steel support 3. One end of the trapezoidal fastener 47 is welded to the top connecting rod 12, and the other end is welded to the trapezoidal fixing block 42 to connect with the standardized steel support 3; a number of connecting short columns 44 are evenly arranged between adjacent trapezoidal fasteners 47, and a jack 35 is installed inside the trapezoidal fastener 47 to further fix the bifurcated box 45; a positioning groove 48 is arranged on the top connecting rod 12 to be fixedly installed corresponding to the positioning block installed at the bottom of the bifurcated box 45.

[0056] In Step 4, as Figure 13 and Figure 14As shown, the chute pipes 5 between adjacent bifurcated boxes 45 are connected to each other through the bifurcated holes 46 and form a certain inclination angle. A vertical chute pipe 55 is arranged at the bottom of the bifurcated box 45 and is connected to the chute pipe 5. A concrete collection trough 54 is installed at the bottom of the standardized steel support 3 to collect the concrete flowing out of the vertical chute pipe 55. Oblique chute pipes 56 are arranged on four sides of the concrete collection trough 54 and are connected to the mobile branch chute 2. The mobile branch chute 2 includes an arc-shaped telescopic chute 59. A number of triangular support frames 57 are installed at the bottom of the arc-shaped telescopic chute 59. A telescopic cylinder 58 is installed on the triangular support frame 57 and is fixed to the arc-shaped telescopic chute 59. When the foundation pit bottom plate 53 is poured, the length of the arc-shaped telescopic chute 59 is changed by adjusting the telescopic cylinder 58, so as to change the concrete outflow position.

[0057] It should be noted that the same or similar parts in this embodiment and Embodiment 2 can be referred to each other, and will not be described in detail in this application.

[0058] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other.

Claims

1. A construction method for pouring an extra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space, characterized in that, It includes the following steps: Step 1: A middle tie rod and a top tie rod are arranged between the telescopic vertical rods of the standardized steel support; a slider is arranged inside the support cross bar, and a support inclined rod is arranged between the slider and the middle tie rod; Step 2: The standardized steel support is connected to the slide rail installed on the top tie rod; prefabricated support segments are arranged between the external square frame and the internal square frame; connecting short rods are arranged on both sides of the external square frame, slide rails are arranged vertically on the inner side of the top tie rod, and the sliding blocks installed on the connecting short rods of the external square frame are placed in the slide rails installed on the top tie rod; a bearing plate is arranged at the bottom of the slide rail, and a jack is installed on the bearing plate to butt against the bottom sliding block; internal tie rods are installed between adjacent sliding blocks to form an integral structure; the position of the sliding block is changed by the jack, so as to adjust the vertical positions of the external square frame and the internal square frame; Step 3: The bifurcation box is installed on the top of the standardized steel support through the bifurcation box fixing system; the bifurcation box fixing system includes an adjustable fastening component and a trapezoidal fastener. The adjustable fastening component is installed on the top of the standardized steel support. The adjustable fastening component includes a side short board and a side long board, and a telescopic bottom board is installed between the side short board and the side long board. The adjustable fastening component makes the side short board press against the bifurcation box through a top tightening screw; trapezoidal fasteners are installed on the other two sides of the standardized steel support. One end of the trapezoidal fastener is welded to the top tie rod, and the other end is welded to a trapezoidal fixing block to be connected with the standardized steel support; a number of connecting short columns are uniformly arranged between adjacent trapezoidal fasteners, and a jack is installed inside the trapezoidal fastener to further fix the bifurcation box; a positioning groove is arranged on the top tie rod to be fixedly installed with the positioning block correspondingly installed at the bottom of the bifurcation box; Step 4: Adjacent bifurcation boxes are connected by a chute pipe. A concrete collection tank is connected to the bottom of the bifurcation box, and the concrete collection tank is connected to a mobile branch chute; the foundation pit bottom slab is poured.

2. The construction method for pouring an extra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space according to claim 1, characterized in that In Step 1, the standardized steel support includes telescopic vertical rods, support cross bars, a bottom plate, U-shaped limit pieces and external threaded rods. Butt columns are arranged at the four corners of the bottom plate. The bottom of the telescopic vertical rod is provided with a butt block and placed inside the butt column arranged on the bottom plate; a top tie rod and a middle tie rod are arranged between the telescopic vertical rods; the support cross bar is fixed to the telescopic vertical rod. A chute is formed by grooving in the middle of the support cross bar. A slider is arranged inside the chute. The slider is connected with a support inclined rod, and the other end of the support inclined rod is connected to the telescopic vertical rod.

3. The construction method for pouring an ultra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space according to claim 2, characterized in that, In Step 1, an internal threaded rod is installed inside the external threaded rod. The internal threaded rod is adjusted and a fastening nut is installed to press against the slider; a pair of arc-shaped connecting plates are welded to the end of the slider, and the arc-shaped connecting plates are connected to the support inclined rod through bearings; a number of bearing rods installed with pyramid cones are uniformly arranged at the bottom of the support cross bar; the limit blocks installed at the ends of the U-shaped limit pieces are placed in the limit grooves arranged at both ends of the middle tie rod, and the middle tie rod is fixed by using connecting screws.

4. The construction method for pouring an ultra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space according to claim 1, characterized in that, In Step 2, the standardized steel support includes an external square frame, an internal square frame, and prefabricated support segments. A shelving bottom plate is arranged between the external square frame and the internal square frame. The prefabricated support segments of the standardized steel support are placed above the shelving bottom plate between the external square frame and the internal square frame. The prefabricated supports of different segments are quickly fixed by inserting the insertion blocks into the threaded jacks, and are further fixed by installing bolts on the docking plates. At the same time, diagonal braces are provided on the prefabricated support segments to strengthen the stability of the structure.

5. The construction method for pouring an extra-large foundation slab of a deep foundation pit with a large-diameter and extra-long chute pipe in a narrow space according to claim 1, characterized in that, In Step 4, the chutes between adjacent bifurcated boxes are connected to each other through the bifurcation holes and form a certain inclination angle. A vertical chute is arranged at the bottom of the bifurcated box and connected to the chute; a concrete collection trough is installed at the bottom of the standardized steel support to collect the concrete flowing out of the vertical chute. Diagonal chutes are arranged on all four sides of the concrete collection trough and connected to the mobile branch chute; the mobile branch chute includes an arc-shaped telescopic chute. A number of triangular support frames are installed at the bottom of the arc-shaped telescopic chute, and telescopic cylinders are installed on the triangular support frames and fixed to the arc-shaped telescopic chute; when pouring the foundation pit floor slab, the length of the arc-shaped telescopic chute is changed by adjusting the telescopic cylinder, so as to change the concrete outflow position.

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