A construction system for reinforcing steel installation of an ultra-thick raft foundation and a construction method thereof

Abstract

The present application relates to the field of building construction, specifically relates to a kind of for super-thick raft foundation steel bar installation construction system and its construction method, installation construction system includes support, the support includes the elevation area support of flat ground and the bottom plate of the lower bottom plate of the elevation area bottom plate, the elevation area support and the elevation area support are all formed by being assembled with several vertical poles and horizontal crosspieces, the lower end surface of the vertical pole of the elevation area of the bottom plate area and the elevation area is abutted with concrete pad, and a layer is provided between the concrete pad and the ground, the bottom of the sump in the bottom plate area is provided, and the bottom of the elevator pit in the elevation area is provided, the vertical pole and the horizontal crosspiece are built together when building the bottom reinforcement of the bottom plate area, and the remaining facilities inside can also be built simultaneously, the whole construction process forms flow construction, avoids the nest work, and greatly improves the construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of building construction, and in particular to a system and method for installing steel reinforcement in ultra-thick raft foundations. Background Technology

[0002] The main challenge in installing ultra-thick raft foundations lies in supporting the raft foundation reinforcement. Traditional steel stirrups are used, but the steel bars used for the stirrups are large in diameter, making them difficult to manufacture. The stirrups are also densely packed, resulting in high labor and time consumption and a large amount of steel. Most importantly, each stirrup is placed independently, which cannot form a support system and makes the raft foundation reinforcement prone to collapse, leading to safety accidents. Using channel steel or H-beams to make independent support columns cannot form a support system and has a low safety factor. Traditional raft foundation construction usually involves building the bottom lowered area first, and then building the top elevation area support after the bottom lowered area is completed. This process takes too long, the project schedule is tight, and repeated construction can easily delay the project. Summary of the Invention

[0003] The purpose of this invention is to address the problems of long construction time, high material consumption and cost, and the risk of independent support overturning due to the continuous increase of load during the construction of the surface steel mesh, as well as the problem of the support system breaking at the base height difference caused by excessive excavation depth of elevator pits and sump pits in raft foundations. This invention provides a construction system and method for installing steel reinforcement in ultra-thick raft foundations.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A construction system for installing reinforcing steel bars in ultra-thick raft foundations includes a support system. The support system comprises an elevation area support system located on a flat ground and a lowered slab area support system with a base plate lower than the base plate of the elevation area support system. Both the lowered slab area support system and the elevation area support system are assembled by several vertical poles and horizontal bars. The lower end faces of the vertical poles of the lowered slab area support system and the elevation area support system abut against concrete pads. An interlayer is provided between the concrete pads and the ground. A sump pit bottom is provided inside the lowered slab area support system, and an elevator pit bottom is provided inside the elevation area support system.

[0006] The elevation area support mentioned in the text refers to the area where the base plate is higher than the base plate of the drop plate area support.

[0007] Therefore, the support used in the steel reinforcement installation system for ultra-thick raft foundations of this invention is a steel pipe. Through the connection between the uprights and horizontal bars, the support forms an unbreakable whole, ensuring that each steel pipe upright bears the load independently while supporting each other. This evenly distributes the top load to each steel pipe, preventing losses due to overturning. Although the foundation bottom has been completely waterproofed and a waterproof protective layer has been poured, if the uprights are directly erected on the waterproof protective layer, any leakage at the foundation bottom will cause the rising water level to overflow through the hollow steel pipes. To solve this problem, this method places concrete pads (expired concrete test blocks can be used as a substitute) before erecting the uprights, resolving the issue of direct contact between the uprights and the waterproof protective layer. Furthermore, to prevent unevenness caused by direct contact between the concrete pads and the ground, an interlayer is provided, allowing the concrete pads to be placed on the interlayer. A sump pit is provided in the middle of the support in the lowered slab area to solve the drainage problem, and an elevator pit is provided in the elevation area of ​​the support, improving safety.

[0008] As a preferred embodiment of the present invention, the uprights and horizontal bars are connected by a direct connector, which makes the connection more stable and the force more even. Furthermore, the uprights penetrate through the support structure in the lowering area and the support structure in the elevation area, so that the support structure in the lowering area can be constructed at the same time as the uprights are erected.

[0009] As a preferred embodiment of the present invention, the lowered slab area support is provided with a lowered slab area bottom reinforcement bar, which is located in the upper area of ​​the concrete pad block. A lowered slab area sweeping bar is provided on the lowered slab area bottom reinforcement bar, and the lowered slab area sweeping bar connects several of the uprights into a whole, so that the uprights and the lowered slab area sweeping bar are connected into a whole, thereby increasing stability. A lowered slab area top reinforcement bar is also provided at the top of the lowered slab area support.

[0010] As a preferred embodiment of the present invention, the support structure of the lowered slab area is equipped with a cooling circulation pipe. The arrangement of the cooling circulation pipe is a physical cooling method adopted to eliminate the large amount of hydration heat generated by the concrete during the raft foundation process, which leads to excessive temperature difference between the inside and outside of the foundation and quality accidents such as temperature cracks. The cooling circulation pipe is located above the sweeping bar of the lowered slab area and is horizontally arranged. Several structural ribs are provided inside the support structure of the lowered slab area to make the structure stable. Bidirectional scissor bracing is provided inside the lowered slab area, and the bidirectional scissor bracing is continuously arranged. The bidirectional scissor bracing is arranged vertically and should be set from bottom to top in the longitudinal and transverse directions on the outer perimeter and inside of the frame.

[0011] As a preferred embodiment of the present invention, the bottom of the elevation area support is provided with an elevation area bottom reinforcement and the top of the elevation area support is provided with an elevation area top reinforcement. Structural reinforcement and elevation area scissor bracing are provided between the elevation area bottom reinforcement and the elevation area top reinforcement. The structural reinforcement is arranged inside the elevation area support and is bent and anchored according to the surrounding contour when it contacts the bottom plate of the elevation area support.

[0012] As a preferred embodiment of the present invention, the bottom of the elevation area support is also provided with an elevation area bottom rib and the top is provided with an elevation area top rib. Furthermore, an elevation area sweeping rod and an elevation area scissor brace are provided inside the elevation area support, making the structure more stable. The elevation area sweeping rod is located in the upper part of the elevation area bottom rib and is horizontally arranged with the elevation area bottom rib, while the cooling circulation pipe is located in the upper part of the elevation area sweeping rod.

[0013] As a preferred embodiment of the present invention, the support body is a steel pipe support.

[0014] A method for installing reinforcing steel bars in an ultra-thick raft foundation, the method being as follows:

[0015] Step 1: Review the construction drawings;

[0016] Step 2: Calculate and verify the stress on the top layer support crossbars, middle layer support crossbars, uprights, and the connection nodes between the uprights and the crossbeams of the steel pipe support to ensure the stability of the steel pipe support;

[0017] Step 3: Based on the stress analysis performed, draw up a technical briefing diagram;

[0018] Step 4: Construct the support structure for the lowered plate area, including setting up the vertical poles, horizontal bars, scissor braces, ground-level bracing, and cooling circulation pipes;

[0019] Step 5: Construct the support structure in the elevation area, including setting up the uprights, horizontal bars, scissor braces, ground bracing, and cooling circulation pipes;

[0020] Step Six: Binding the reinforcing bars. The long-span reinforcing bars are arranged at the bottom and the short-span reinforcing bars are arranged at the top. The intersections of the reinforcing bars should be fully bound with three or more strands of binding wire. The binding wires at adjacent intersections should be tied into a figure-eight knot to prevent the reinforcing bars from slipping in the same direction.

[0021] Step 7: After the construction work is completed, the construction team shall first conduct a self-inspection. After the self-inspection is qualified, it shall be reported to the on-site management personnel of the construction unit for inspection. After the on-site management personnel of the construction unit accept the inspection, a written acceptance application shall be submitted to the professional supervising engineer of the supervision unit for acceptance. After the professional supervising engineer accepts the inspection, the construction unit shall submit a concrete pouring application. After approval, the acceptance procedure shall be completed and the construction unit shall organize the concrete pouring construction.

[0022] As a preferred embodiment of the present invention, the construction method of the support for the lowered plate area in step four is as follows: the bottom reinforcement of the support for the lowered plate area is tied, the uprights and horizontal bars are erected, and then the cooling circulation pipes, the scissor bracing of the lowered plate area, and the sweeping bar of the lowered plate area are arranged.

[0023] As a preferred embodiment of the present invention, the construction method of the elevation area support in step five is as follows: the bottom reinforcement of the elevation area is arranged and tied on the elevation area support, and then the uprights and horizontal bars are erected. After the arrangement is completed, the cooling circulation pipes, the elevation area scissor bracing, and the elevation area sweeping bar are arranged.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. This invention relates to a construction system for installing reinforcing steel bars in ultra-thick raft foundations. It connects independent steel pipe uprights into a unified system using ground-level bracing and horizontal crossbars, effectively preventing the risk of independent supports overturning due to increasing load during the binding of the surface steel mesh. It also solves the problem of broken support systems at elevation differences in the raft foundation caused by excessively deep excavation of elevator pits and sump pits. Because of the integrated ground-level bracing and horizontal crossbars, the density of the steel pipe uprights can be appropriately reduced. This achieves the goal of controlling costs and reducing input costs. Furthermore, the use of steel pipe supports in this invention has good effects on improving efficiency, ensuring safety, ensuring progress, and controlling costs.

[0026] 2. This invention is a construction method for installing steel reinforcement in ultra-thick raft foundations. As the support system moves forward in sections, the binding of steel reinforcement also begins. This method can effectively ensure that the steel reinforcement is bound in one go, fundamentally eliminating the hidden dangers of steel reinforcement slippage and repeated installation and dismantling that delay the construction period. Attached Figure Description

[0027] Figure 1 This is a flowchart of the installation and construction method of the present invention;

[0028] Figure 2 This is a schematic diagram of the support structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the elevation area structure of the present invention;

[0030] Figure 4 This is a schematic diagram of the crossbar connection structure of the present invention;

[0031] Figure 5 This is a detailed installation flowchart of the present invention.

[0032] Icons: 1-Upright pole; 2-Horizontal crossbar; 3-Raft slab; 4-Elevator pit bottom; 5-Sump pit bottom; 6-Scissor bracing in the lowered slab area; 7-Concrete pad; 8-Top reinforcement in the lowered slab area; 9-Bottom reinforcement in the lowered slab area; 10-Structural reinforcement; 11-Sweeping bar in the lowered slab area; 12-Support; 13-Sweeping bar in the elevation area; 14-Scissor bracing in the elevation area; 15-Bottom reinforcement in the elevation area; 16-Top reinforcement in the elevation area; 17-Direct connector; 18-Mezzanine; 19-Cooling circulation pipe; 12a-Support in the elevation area; 12b-Support in the lowered slab area. Detailed Implementation

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

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

[0035] Example 1

[0036] A reinforcement installation system for ultra-thick raft foundations includes a support frame 12. The support frame 12 comprises an elevation zone support 12a on level ground and a lowered zone support 12b with a lower base plate than the elevation zone support 12a. Both the elevation zone support 12a and the lowered zone support 12b are internally formed by interlocking vertical poles 1 and horizontal crossbars 2. This interlocking arrangement of the vertical poles 1 and horizontal crossbars 2 disperses the force on the support frame 12. The system is constructed within the elevation zone support 12a and the lowered zone support 12b. The lower end face of the upright 1 abuts against a concrete pad 7 to prevent leakage at the bottom of the foundation. Rising water overflows through a hollow steel pipe. A partition 18 is provided between the concrete pad 7 and the ground to make the concrete pad 7 more level. The area below the upright 1 in the elevation area support 12a and the lowering area support 12b is respectively equipped with an elevation area sweeping rod 13 and a lowering area sweeping rod 11. The lowering area support 12b has a water collection pit bottom 5 for drainage. The elevation area support 12a has an elevator pit bottom, such as... Figure 2 As shown.

[0037] This invention relates to a construction system for installing reinforcing steel bars in ultra-thick raft foundations. A support structure is built by arranging the uprights 1 and horizontal crossbars 2 in a crisscross pattern. The independent steel pipe uprights 1 are connected into a unified whole by the ground-level bracing and horizontal crossbars 2, forming a complete support system. This effectively avoids the risk of independent supports overturning due to increasing load during the binding process of the surface steel mesh. It also solves the problem of the support system breaking at the elevation difference points in the raft foundation caused by excessively deep excavation of the elevator pit bottom 5 and sump pit bottom 4.

[0038] The aforementioned upright 1 and horizontal crossbar 2 are connected by a straight connector 17. The straight connector 17 makes the connection between the upright 1 and the horizontal crossbar 2 more robust, and the upright 1 must not be disconnected from the horizontal crossbar 2. Figure 4 As shown

[0039] The bottom of the aforementioned drop slab support 12b is provided with the drop slab bottom reinforcement 9 and the drop slab top reinforcement 8 to increase the load-bearing capacity. The bottom reinforcement 9 of the drop slab support 12b is positioned above the concrete pad 7 and abuts against the concrete pad 7. A drop slab sweeping bar 11 is horizontally positioned above the bottom reinforcement 9. The top of the drop slab support 12b is also provided with the drop slab top reinforcement 8, thus constructing a complete drop slab support 12b. Figure 2 As shown.

[0040] The aforementioned support 12b in the lowered slab area is equipped with cooling circulation pipes 19. These pipes are laid above the horizontally positioned sweeping rods 11 in the lowered slab area. The arrangement of the cooling circulation pipes 19 is a physical cooling method to eliminate the large amount of heat of hydration generated during the pouring of the large-volume concrete in the raft foundation, which can lead to excessive temperature differences between the inside and outside of the foundation and quality issues such as temperature cracks. The support 12b in the lowered slab area is equipped with several structural reinforcement bars 10. These bars are built within the support structure of the lowered slab area support 12b and are bent and anchored at the bends in the support profile to maintain structural stability. Qualitatively, the lowering area support 12b is also equipped with lowering area scissor bracing 6, which is continuously arranged inside the lowering area support 12b. After the upright 1 is fixed, the lowering area scissor bracing 6 and the lowering area sweeping rod 11 are arranged for reinforcement. The lowering area sweeping rod 11 is arranged in both directions with the shorter span at the bottom and the longer span at the top. According to the depth of the foundation pit of the lowering area support 12b, continuous vertical lowering area scissor bracing 6 should be set from bottom to top on the outer perimeter and the inner longitudinal and transverse directions of the frame. The width of the lowering area scissor bracing 6 is not greater than four spans, and the angle with the ground is between 45° and 60°. Figure 2 As shown.

[0041] The aforementioned elevation area support 12a has an elevation area bottom rib 15 at its bottom and an elevation area top rib 16 at its top. A structural rib 10 and a bidirectional scissor brace 14 are provided between the elevation area bottom rib 15 and the elevation area top rib 16. The elevation area sweeping rod 13 and the elevation area scissor brace 14 on the elevation area support 12a are arranged identically to those on the lowering plate area support 12b. This increases the overall structural stability of the elevation area support 12a. Figure 3 As shown.

[0042] The upper end of the bottom rib 15 of the aforementioned elevation area is horizontally provided with an elevation area sweeping rod 13, and the upper end of the elevation area sweeping rod 13 is provided with a cooling circulation pipe 19, such as... Figure 3 As shown.

[0043] The aforementioned support 12 is a steel pipe support.

[0044] Therefore, this invention first constructs the uprights 1 in the support 12b of the lowered slab area. After the uprights 1 are constructed, the ground-level bracing 14 in the elevation area and the ground-level bracing 11 in the lowered slab area are constructed, thereby ensuring the stability of the structure. The structural reinforcement 10, the scissor bracing 6 in the lowered slab area, and the scissor bracing 14 in the elevation area are constructed inside the support 12 to ensure the safety and stability of the constructed steel reinforcement support. Furthermore, a cooling circulation pipe 19 is also provided inside the support 12. This is a physical cooling method adopted to address quality accidents such as temperature cracks caused by excessive temperature differences between the inside and outside of the foundation due to the large volume of concrete poured for the raft foundation and the heat generated when the concrete comes into contact with water. Cold water is injected into the concrete through heat exchange, and hot water flows out to displace the heat. Simultaneously, a temperature detection device is used to control the temperature difference between the inside and outside of the foundation. For areas with lowered concrete slabs, the arrangement of cooling circulation pipes requires careful consideration of parameters such as material, spacing, number of layers, and loop units. Pipe material is primarily determined by the ambient temperature during construction, while also taking cost into account. If the average outdoor temperature is similar to the concrete hydration heat parameters provided by the laboratory, DN32 to DN50 PE pipes are sufficient. If the difference is significant, metal pipes with higher thermal conductivity should be considered, and the pipe diameter should be appropriately increased according to the flow rate requirements, but should not exceed DN50. The spacing, number of layers, and loop units of the cooling circulation pipes are mainly determined by the thickness of the concrete structure. For concrete structures with a thickness of 3m or less, the cooling circulation pipes are arranged in one layer with a spacing of no more than 2m, and the coverage area of ​​a single loop unit should not exceed 400㎡. For thicknesses exceeding 3m, the number of cooling circulation pipe layers should be increased accordingly, and the pipe spacing reduced. Specific data are determined through cooling efficiency calculations. The cooling circulation pipe 19 is fixed to the horizontal crossbar 2 with tie wire according to the layout diagram. The inlet and outlet are reserved in the bracket 12a at the elevation area for later connection. In this invention, the bracket is built with steel pipe brackets, and the steel pipe bracket support system is used for steel reinforcement installation. The key point is that it does not rely on individual steel pipe uprights 1 to bear the load independently, but is effectively connected to the horizontal steel pipe 2 through cross fasteners to form an unbreakable whole. This allows each steel pipe upright 1 to bear the load independently and support each other, and evenly distributes the top load to each steel pipe. The erection of uprights 1 and the middle horizontal crossbar begins when the bottom reinforcement of the raft slab is tied. After the bottom reinforcement is tied, the uprights 1 and the horizontal crossbar are also erected. The next three tasks, namely the erection of the bracket top pipe, the arrangement of the middle cooling circulation pipe, and the connection of the sweeping bar, can be carried out and completed simultaneously. The last step is to tie the top reinforcement of the raft slab. The entire construction process forms a continuous construction, avoiding idle work and greatly improving construction efficiency.

[0045] This invention also possesses certain economic advantages. Compared to traditional steel stirrups and channel steel supports, the steel pipe support uses prefabricated, fixed-length steel pipes, eliminating the need for on-site processing and secondary transportation. Furthermore, because it incorporates ground-level bracing and horizontal crossbars to form a unified structure, the density of the steel pipe uprights can be appropriately reduced. This achieves the goal of controlling costs and reducing investment. A comparative analysis is conducted using all unit projects in this project with 2.2m thick raft foundations as examples, as detailed below:

[0046] The foundation areas of buildings #2, #3, and #13 are basically the same, the raft foundation thickness is 2.2m, the resource allocation is the same, and the construction period is 12 days for all three. Therefore, they can be classified into the same type of calculation and analysis. The economic benefits will now be compared and analyzed based on a single foundation:

[0047] Steel pipe support:

[0048] 2 management personnel (salary 350 yuan / day), 5 scaffolders (salary 400 yuan / day), 1600m of steel pipe (14 yuan / m), 470 connectors (4 yuan / piece).

[0049] Labor costs: Management personnel = 350 × 12 × 2 = 8,400 yuan

[0050] Construction workers = 400 × 7 × 5 = 14,000 yuan;

[0051] Material cost: Steel pipe (main material) = 14 × 1600 = 22,400 yuan

[0052] Connectors (auxiliary materials) = 4 × 470 = 0.19 million yuan

[0053] Other expenses: 3,000 yuan

[0054] Steel stirrups:

[0055] 2 management personnel (salary 350 yuan / day), 5 steelworkers (salary 350 yuan / day), 2 welders (salary 350 yuan / day), 10.43 tons of steel bars (4500 yuan / ton), 30 packs of welding rods (90 yuan / pack).

[0056] Labor costs: Management personnel = 350 × 12 × 2 = 8,400 yuan

[0057] Construction workers = 350 × 7 × 5 + 350 × 3 × 2 = 14,400 yuan

[0058] Material cost: Steel bars (main material) = 10.43 × 4500 = 46,900 yuan

[0059] Welding electrodes (auxiliary materials) = 30 × 90 = 0.27 million yuan

[0060] Other expenses: 0.24 million yuan

[0061] Channel steel support:

[0062] 2 management personnel (salary 350 yuan / day), 3 skilled workers (salary 350 yuan / day), 4 welders (salary 350 yuan / day), 440m of channel steel (100 yuan / m), 40 packs of welding rods (90 yuan / pack).

[0063] Labor costs: Management personnel = 350 × 12 × 2 = 8,400 yuan

[0064] Construction workers = 350 × 7 × 7 = 17,200 yuan

[0065] Material cost: Channel steel (main material) = 440 × 100 = 44,000 yuan

[0066] Welding electrodes (auxiliary materials) = 40 × 90 = 0.36 million yuan

[0067] Other expenses: 3,200 yuan

[0068] The foundation areas of buildings #4, #5, #6, #10, #13, and #15 are basically the same, the raft foundation thickness is 2.2m, the resource allocation is the same, and the construction period is 15 days for all of them. They can be classified into the same type of calculation and analysis. Now, we will conduct an economic benefit comparison analysis based on a single foundation:

[0069] Steel pipe support:

[0070] Two management personnel (salary 350 yuan / day), five scaffolders (salary 400 yuan / day), 3200m of steel pipe (14 yuan / m), and 940 connectors (4 yuan / each).

[0071] Labor costs: Management personnel = 350 × 15 × 2 = 10,500 yuan

[0072] Construction workers = 400 × 12 × 5 = 24,000 yuan;

[0073] Material cost: Steel pipe (main material) = 14 × 3200 = 44,800 yuan

[0074] Connectors (auxiliary materials) = 4 × 940 = 0.38 million yuan

[0075] Other expenses: 0.6 million yuan

[0076] Steel stirrups:

[0077] 2 management personnel (salary 350 yuan / day), 5 steelworkers (salary 350 yuan / day), 2 welders (salary 350 yuan / day), 20.86 tons of steel bars (4500 yuan / ton), 60 packs of welding rods (90 yuan / pack).

[0078] Labor costs: Management personnel = 350 × 15 × 2 = 10,500 yuan

[0079] Construction workers = 350 × 12 × 5 + 350 × 5 × 2 = 24,500 yuan

[0080] Material cost: Steel bars (main material) = 20.86 × 4500 = 93,900 yuan

[0081] Welding electrodes (auxiliary materials) = 60 × 90 = 0.54 million yuan

[0082] Other expenses: 4,800 yuan

[0083] Channel steel support:

[0084] 2 management personnel (salary 350 yuan / day), 3 skilled workers (salary 350 yuan / day), 4 welders (salary 350 yuan / day), 880m of channel steel (100 yuan / m), 80 packs of welding rods (90 yuan / pack).

[0085] Labor costs: Management personnel = 350 × 15 × 2 = 10,500 yuan

[0086] Construction workers = 350 × 12 × 7 = 29,400 yuan

[0087] Material cost: Channel steel (main material) = 880 × 100 = 88,000 yuan

[0088] Welding electrodes (auxiliary materials) = 80 × 90 = 0.72 million yuan

[0089] Other expenses: 0.64 million yuan

[0090] The total data for the eight buildings is shown in the table below:

[0091]

[0092]

[0093] Example 2

[0094] A method for installing reinforcing steel bars in an ultra-thick raft foundation, such as Figure 1 The method shown is as follows:

[0095] Step 1: Review the construction drawings;

[0096] Step 2: Calculate and verify the stress on the top layer support crossbar, the middle layer support crossbar, the upright 1, and the connection node between the upright 1 and the crossbeam of the steel pipe support to ensure the stability of the steel pipe support;

[0097] Step 3: Based on the stress calculation results of the steel pipe support, draw a plan and elevation diagram of the steel pipe support, and prepare a technical briefing in conjunction with relevant specifications, and conduct a three-level briefing;

[0098] Step 4: Construct the support 12b for the lowered plate area, and install the upright 1, horizontal crossbar 2, scissor brace 6 for the lowered plate area, sweeping bar 11 for the lowered plate area, and cooling circulation pipe 19;

[0099] Step 5: Construct the support structure for the elevation area, including setting up the uprights 1, horizontal bars 2, elevation area scissor bracing 14, elevation area ground sweeping bars 13, and cooling circulation pipes 19;

[0100] Step Six: Binding the reinforcing bars. The long-span reinforcing bars are arranged at the bottom and the short-span reinforcing bars are arranged at the top. The intersections of the reinforcing bars should be fully bound with three or more strands of binding wire. The binding wires at adjacent intersections should be tied into a figure-eight knot to prevent the reinforcing bars from slipping in the same direction.

[0101] Step 7: After the construction work is completed, the construction team shall first conduct a self-inspection. After the self-inspection is qualified, it shall be reported to the on-site management personnel of the construction unit for inspection. After the on-site management personnel of the construction unit accept the inspection, a written acceptance application shall be submitted to the professional supervising engineer of the supervision unit for acceptance. After the professional supervising engineer accepts the inspection, the construction unit shall submit a concrete pouring application. After approval, the acceptance procedure shall be completed and the construction unit shall organize the concrete pouring construction.

[0102] In steps four and five above, the support 12b in the lowering area and the support 12a in the elevation area are constructed using the same method. Figure 5 As shown, they are:

[0103] Binding of bottom reinforcement: For the bottom reinforcement in the drop slab area, first mark the reinforcement layout and position it, then place protective layer spacers according to the positioning. Follow the principle of unidirectional construction, first arrange the short span reinforcement and then the long span reinforcement. At the intersection of the reinforcement, use at least three strands of tie wire to fully bind them. Tie the tie wires at adjacent intersections into a figure-eight knot to prevent the reinforcement from slipping in the same direction. Note that after the side wall bent reinforcement is arranged, tie the horizontal reinforcement in time to fix it to prevent the reinforcement from tilting to one side.

[0104] Erection of upright pole 1 and horizontal bar 2: First, position upright pole 1. As a component that runs through the entire foundation raft slab, although the bottom of the foundation has been completely waterproofed and a waterproof protective layer has been poured, if the upright pole 1 is directly erected on the waterproof protective layer, then once leakage occurs at the bottom of the foundation, the rising water level will overflow through the hollow steel pipe. At the same time as erection, the horizontal bar is connected with a direct connector according to the step distance requirements. The construction of both is carried out simultaneously to ensure that the upright pole 1 is stable and upright.

[0105] Erection of scissor bracing and ground-level bracing: After fixing the upright 1, scissor bracing and ground-level bracing are arranged for reinforcement. The ground-level bracing is arranged in both directions with the shorter span at the bottom and the longer span at the top. According to the depth of the foundation pit in the lowering area, continuous vertical scissor bracing should be set from bottom to top on the outer perimeter and the inner longitudinal and transverse directions of the frame. The width of the scissor bracing should not be greater than four spans, and the angle with the ground should be between 45° and 60°.

[0106] Setting of cooling circulation pipe 19: The cooling circulation pipe in the lower plate area is fixed to the horizontal bar 2 with tie wire according to the layout diagram. The water inlet and outlet are reserved in the bracket in the elevation area for easy connection later.

[0107] Steps four and five above can be carried out simultaneously. After the bottom reinforcement 9 in the lowering plate area is tied in step four, the upright 1 is set up. After the upright 1 is set up, the ground sweeping bar 13 in the elevation area is erected, so that the support 12b in the lowering plate area and the support 12a in the elevation area can be erected at the same time.

[0108] The stress calculation for the steel pipe support in step two above is as follows:

[0109] (1) Calculation basis

[0110] Steel Structure Design Standard GB50017-2017

[0111] (2) Parameter information

[0112] Steel pipe supports are mainly used for ultra-thick raft foundations of high-rise buildings. The supports, constructed using steel pipes and fasteners, support the surface reinforcement, control the thickness of the concrete cover and the finished concrete elevation, and also bear the loads of construction work and equipment.

[0113] The steel pipe scaffold is constructed using fasteners to form a support system. Stability and strength are calculated for the uprights and diagonal members, while stiffness and strength are calculated for the horizontal members.

[0114] a. Basic parameters

[0115]

[0116] b. Beam parameters

[0117]

[0118] c. Pole parameters

[0119]

[0120] (3) Calculation of the crossbars of the top-level support

[0121] a. Calculation of uniformly distributed load value

[0122] Calculation of static load: q1 = 1.2 × 2.00 × 0.66 = 1.58 kN / m;

[0123] Live load calculation: q2 = 1.4 × 0.10 × 2.00 + 1.4 × 0.10 × 2.00 = 0.56 kN / m

[0124] b. Strength Calculation

[0125] The maximum bending moment at mid-span is:

[0126] M1 = 0.08q1l2 + 0.101q2l2

[0127] =(0.08×1.58+0.101×0.56)×2.002=0.733kN·m

[0128] The maximum bending moment at the support is:

[0129] M2 = -0.10q1l2 - 0.117q2l2

[0130] =-(0.10×1.58+0.117×0.56)×2.002=-0.896kN·m

[0131] We selected the maximum values ​​of the support bending moment and the mid-span bending moment for strength verification:

[0132] σ=0.896×106 / 4250.00=210.748N / mm2<215N / mm2

[0133] c. Deflection Calculation

[0134] The formula for calculating the maximum deflection is as follows:

[0135] νmax=(0.677q1+0.990q2)l4 / 100EI

[0136] The standard value of static load q1 = 1.32 kN / m

[0137] The standard value of live load q2 = 0.10 × 2.00 + 0.10 × 2.00 = 0.40 kN / m

[0138] The maximum deflection of a three-span continuous beam under uniformly distributed load is:

[0139] νmax=(0.677×1.32+0.990×0.40)×2000.004 / (100×2.05×105×10.19×104)=9.8778mm<Min(2.00×103 / 150,10)=10.00mm

[0140] (4) Calculation of crossbars of intermediate layer support

[0141] a. Calculation of uniformly distributed load value

[0142] Static load calculation: q2 = 1.2 × 2.00 × 0.07 = 0.17 kN / m

[0143] b. Strength Calculation

[0144] The maximum bending moment is:

[0145] M=0.1q2l2=0.1×0.168×22=0.067kN·m

[0146] σ=M / W=0.067×106 / 4.25×103=15.812N / mm2≤215N / mm2

[0147] c. Deflection Calculation

[0148] The calculated value of the static load is q2' = 0.07 × 2.00 = 0.14 kN / m

[0149] νmax=0.677q2'l4 / 100EI=0.677×0.14×20004 / (100×2.05×105×10.19×104)=0.7260mm<Min(2.00×103 / 150,10)=10.00mm

[0150] (5) Calculation of the uprights

[0151] The cross-sectional area of ​​the upright is A = 3.98 cm².

[0152] Radius of gyration i = 1.60 cm

[0153] Stability check of the upright pole under axial compression:

[0154] σ=N / φA≤[f]

[0155] In the formula:

[0156] σ──compressive stress of the upright;

[0157] N – Design value of axial pressure;

[0158] a. Slenderness ratio verification:

[0159] λ=h / i=200.00 / 1.60=125≤250

[0160] b. Stability verification:

[0161] φ──Stability coefficient of axially compressed member. From the slenderness ratio λ=125, we can find that φ=0.423.

[0162] [f]──Design value of compressive strength of the upright, [f]=215N / mm2;

[0163] Repeating the load combination calculation method described above, the maximum support reaction force of the vertical pole on the horizontal pole is:

[0164] Nmax = 1.1Σq1l + 1.2q2l

[0165] The calculated value is N = 1.1 × [1.2 × 2 × (0.66 + 0.07)] × 2 + 1.2 × 0.56 × 2 = 5.198 kN;

[0166] σ=5.198×1000 / (0.423×3.98×100)=30.878N / mm2<215.00N / mm2

[0167] (6) Verification of the connection node between the upright and the crossbeam

[0168] a. Fastener anti-slip calculation

[0169] Nmax = 5.198kN <Rc=kc×8=8×0.85=6.8kN

[0170] Therefore, this invention provides a method for installing steel reinforcement supports for ultra-thick raft foundations. The key is that it does not rely on individual steel pipe uprights for independent load-bearing. Instead, it effectively connects the uprights to the horizontal steel pipes using cross-shaped fasteners, forming an unbreakable whole. This allows each upright to both bear load independently and support each other, evenly distributing the top load to each pipe. The erection of the uprights and central horizontal bars begins during the binding of the bottom reinforcement of the raft foundation. Once the bottom reinforcement is bound, the uprights and horizontal bars are also erected. The subsequent erection of the support top pipes, the arrangement of the central cooling circulation pipes, and the connection of the sweeping bars can then be carried out and completed simultaneously. The final step is binding the top reinforcement of the raft foundation. The entire construction process is a continuous flow, avoiding idle work and greatly improving construction efficiency.

[0171] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for installing reinforcing steel bars in ultra-thick raft foundations, characterized in that, The system includes a reinforcement installation system for ultra-thick raft foundations, comprising a support (12). The support (12) includes an elevation area support (12a) located on a flat ground and a lowered slab area support (12b) with a base plate lower than that of the elevation area support (12a). Both the lowered slab area support (12b) and the elevation area support (12a) are assembled from several uprights (1) and horizontal bars (2). The lower end face of the uprights (1) of the lowered slab area support (12b) and the elevation area support (12a) abuts against a concrete pad (7). An interlayer (18) is provided between the concrete pad (7) and the ground. The lowering area support (12b) has a sump bottom (5) inside, and the elevation area support (12a) has an elevator pit bottom (4) inside. The upright (1) and the horizontal crossbar (2) are connected by a direct head (17). The upright (1) passes through the elevation area support (12a) and the lowering area support (12b). The bottom of the lowering area support (12b) has a lowering area bottom reinforcement (9) and the lowering area bottom reinforcement (9) is located above the concrete pad (7). A lowering area sweeping bar (11) is provided horizontally above the lowering area bottom reinforcement (9). The top of the lowering area support (12b) is... The section also has a rib (8) for the lowered plate area. The lowered plate area support (12b) is equipped with a cooling circulation pipe (19). The cooling circulation pipe (19) is located above the lowered plate area sweeping bar (11) and is horizontally arranged. The lowered plate area support (12b) is equipped with several structural ribs (10) along the contour inside. The structural ribs (10) are arranged inside the support (12). The lowered plate area support (12b) is equipped with continuously arranged lowered plate area scissor braces (6). The lowered plate area sweeping bar (11) is arranged in both directions with the short span at the bottom and the long span at the top. According to the depth of the foundation pit of the lowered plate area support (12b), the frame body The outer perimeter and the inner longitudinal and transverse directions should be provided with continuous vertical scissor bracing (6) for the lower plate area from bottom to top. The bottom of the elevation area support (12a) is provided with elevation area bottom reinforcement (15), and the top of the elevation area support (12a) is provided with elevation area top reinforcement (16). Structural reinforcement (10) and elevation area scissor bracing (14) are provided between the elevation area bottom reinforcement (15) and the elevation area top reinforcement (16). The upper end of the elevation area bottom reinforcement (15) is provided with elevation area sweeping rod (13), and the upper end of the elevation area sweeping rod (13) is provided with cooling circulation pipe (19). The support (12) is a steel pipe support. Also includes: S1. Review the construction drawings; S2. Calculate the stress of the top layer support crossbar, the middle layer support crossbar, the upright (1), and the connection node between the upright (1) and the crossbeam to ensure the stability of the steel pipe support. S3. Based on the stress calculation results of the steel pipe support, draw a plan and elevation schematic diagram of the steel pipe support, and prepare a technical briefing in conjunction with relevant specifications, and conduct a three-level briefing. S4. Construct the support (12b) for the lowered plate area, and set up the upright (1), the horizontal crossbar (2), the scissor brace (6) for the lowered plate area, the sweeping bar (11) for the lowered plate area, and the cooling circulation pipe (19). S5. Construct the support structure for the elevation area, and install the uprights (1), the horizontal bars (2), the scissor bracing (14), the ground sweeping bars (13), and the cooling circulation pipes (19). S6. When tying the reinforcing bars, the long-span reinforcing bars at the top should be arranged with the short-span reinforcing bars at the bottom and the short-span reinforcing bars at the top. The reinforcing bar intersections should be fully tied with three or more strands of binding wire. The binding wires at adjacent intersections should be tied into a figure-eight knot to prevent the reinforcing bars from slipping in the same direction. S7. Carry out concrete pouring construction; Steps S4 and S5 are carried out simultaneously, specifically as follows: Step 1: After the bottom reinforcement (9) of the lowered plate area is tied up, the upright (1) is installed. Step 2: After the pole (1) is set up, construct the sweeping pole (13) for the elevation area and the sweeping pole (11) for the lowering area. Step 3: After the elevation area sweeping rod (13) and the lowering plate area sweeping rod (11) are erected, the lowering plate area support (12b) and the elevation area support (12a) are constructed simultaneously.

2. The method for installing reinforcing steel bars in an ultra-thick raft foundation according to claim 1, characterized in that, The construction method for the support (12b) of the lowering plate area in step S4 is as follows: binding the bottom reinforcement (9) of the lowering plate area, then building the upright (1) and the horizontal crossbar (2), followed by arranging the cooling circulation pipe (19), and arranging the scissor brace (6) and the sweeping bar (11) of the lowering plate area.

3. The method for installing reinforcing steel bars in an ultra-thick raft foundation according to claim 1, characterized in that, The construction method for the elevation area support (12a) in step S5 is as follows: tie the bottom reinforcement (15) of the elevation area on the elevation area support (12a), then build the upright (1) and the horizontal bar (2), and then arrange the cooling circulation pipe (19), as well as arrange the scissor brace (14) of the elevation area and the sweeping bar (13) of the elevation area.

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