Integrated Construction Process of Basement Exterior Wall Steel Structure Self-Waterproofing Single-Sided Formwork System Based on BIM Technology

Abstract

This invention belongs to the field of building construction technology, specifically a comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior wall steel structures based on BIM technology. During construction, BIM technology is first used for detailed design, followed by the sequential installation of embedded plates, adjustable horizontal channel steel, main and secondary keels, and multi-layer plywood. Then, high-strength cement composite boards are installed layer by layer, and impermeable concrete with added silica densifier is poured in layers. This invention solves the problems of difficult and inefficient construction using traditional brick formwork in narrow, cramped spaces through an adjustable steel structure; it utilizes high-strength cement composite boards as a waterproof base layer, forming a multi-layered waterproof combination with the impermeable concrete, significantly improving the impermeability of the exterior wall; simultaneously, the steel structure can be reused, saving costs and reducing construction waste, resulting in significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, specifically relating to a comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior steel structure based on BIM technology. Background Technology

[0002] In modern urban construction, especially in high-rise buildings and large-scale complex projects, basement structures with large areas and deep foundation pits are often designed to meet functional requirements (such as garages and equipment rooms) and greening requirements. Due to planning boundary restrictions or the needs of foundation pit support structures, the working space (commonly known as "fat trench") between the exterior walls of the basement structure and the foundation pit slope protection piles (walls) is often very narrow.

[0003] Traditional basement exterior wall construction in cramped trenches typically uses brick formwork as the outer mold. However, masonry and plastering require a certain amount of operating space, making construction in cramped trenches extremely inconvenient or even impossible. The amount of wet work involved in brick formwork masonry and plastering is large, the procedures are numerous, and the curing period is long, which seriously affects the overall construction progress. Furthermore, the brick formwork itself has poor waterproof performance and is only used as a template. A separate waterproof layer needs to be applied to its surface. In addition, the brick masonry is prone to settlement and deformation, which can lead to cracking and leakage of the waterproof layer. Summary of the Invention

[0004] The purpose of this invention is to provide a comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior steel structures based on BIM technology. This process can effectively solve the construction difficulties in narrow trenches, improve construction efficiency, and ensure quality and waterproof performance.

[0005] The specific technical solution adopted by this invention is as follows: A comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior steel structures based on BIM technology includes the following steps: Step 1: BIM Detailed Design and Construction Preparation: Use BIM technology to create a 3D model, conduct detailed design and collision detection for embedded plates, main keel, secondary keel and waterproofing system, optimize layout, and generate construction drawings and material lists. Step 2, Embedded Plate Installation: Based on the BIM layout and positioning, clean the surface of the slope protection piles, and use expansion bolts to fix the embedded plates to the slope protection piles at the designed spacing; Step 3: Install the adjustable horizontal channel steel: Weld one end of the prefabricated adjustable horizontal channel steel to the embedded plate on both sides, and adjust the length through its own arc hole and bolts to keep the ends of all adjustable horizontal channel steels on the same plane in the vertical direction. Step 4: Install the main and secondary keels: Weld the main keel horizontally to the adjustable horizontal channel steel, and then weld the secondary keel vertically to the main keel to form a steel structure support frame; Step 5: Install plywood: Fix the plywood to the secondary joists using self-tapping screws; Step 6: Install high-strength cement composite board: First, install one layer of high-strength cement composite board onto the multi-layer plywood, and then pour impermeable concrete with added silica densifier; after the concrete layer is poured, install the next layer of high-strength cement composite board and continue pouring concrete, and repeat this cycle until the exterior wall construction is completed. Step 7: Integrate the flexible waterproofing system for the roof slab; assemble precast rolled foam boards on the basement roof slab, install flexible drainage channels, backfill with gravel filler layer, lay polyurea elastic pads, and finally assemble the floor decorative panels.

[0006] A BIM-based self-waterproofing single-sided formwork system for basement exterior steel structures, comprising: Multiple embedded plates are fixed to the pile body of the slope protection pile at intervals by expansion bolts; Multiple adjustable horizontal channel steels, one end of which is vertically fixed to the embedded plate, and the other end extends horizontally into the trough; The main keel is a horizontally arranged channel steel, which is fixedly connected to multiple adjustable horizontal channel steels to form a transverse support frame; The secondary keel is a vertically arranged channel steel, which is fixed at intervals to the main keel to form a vertical support frame; Multi-layer plywood is installed on the secondary keel with self-tapping screws to form a template panel; High-strength cement composite board is installed in layers on the outer side of the multi-layer plywood using self-tapping screws, serving as a waterproof base layer.

[0007] Furthermore, the adjustable horizontal channel steel is formed by connecting two channel steel bodies with bolts. One of the channel steels has an arc-shaped hole on its side wall for adjusting the overlap length of the two channel steels. The bolt passes through the arc-shaped hole to fasten the two channel steels together.

[0008] Furthermore, it also includes a flexible waterproofing system for basement roof slabs, the flexible waterproofing system comprising a precast roll foam board laid on the roof slab, a flexible drainage channel set on the foam board, and a gravel filler layer and a polyurea elastic pad covering the periphery of the flexible drainage channel.

[0009] The technical effects achieved by this invention are as follows: (1) The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology adopts a steel structure single-sided formwork system, which eliminates the need for masonry and plastering operations in the trench, requires less operating space, and fundamentally solves the construction problem in the narrow trench. The steel structure components can be prefabricated in the factory and assembled on site, which speeds up the construction and greatly shortens the construction period.

[0010] (2) The steel structure support system constructed by the integrated construction process of the basement exterior wall steel structure self-waterproof single-sided formwork system based on BIM technology has high rigidity, good stability, and is not easily deformed, which can ensure the forming size and verticality of the concrete exterior wall. Through the design of adjustable horizontal channel steel, the unevenness of the slope protection pile surface can be compensated, ensuring the overall flatness and stability of the formwork system.

[0011] (3) The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology of the present invention constructs a multi-layer composite waterproofing system of "structural self-waterproofing (anti-seepage concrete) + material waterproofing (high-strength cement composite board)". The high-strength cement composite board is not only a component of the formwork, but also a flat and solid waterproof base layer, which is closely combined with the anti-seepage concrete to effectively eliminate the risk of leakage. Combined with the patented waterproofing device, a flexible waterproofing system of "drainage and prevention combination" can also be formed on the top slab.

[0012] (4) The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology of the present invention allows the steel structure to be disassembled and reused, reducing material costs; it also reduces the consumption of materials such as bricks and mortar and the generation of construction waste, which meets the requirements of green environmental protection. By optimizing material cutting through BIM technology, the material utilization rate is further improved, and the overall economic benefits are obvious. Attached Figure Description

[0013] Figure 1 This is a flowchart of the construction process of the present invention; Figure 2 This is a side view of the basement exterior wall formwork structure of the present invention; Figure 3 This is a top view of the basement exterior wall formwork structure of the present invention; Figure 4 This is a schematic diagram of the adjustable horizontal channel steel structure of the present invention; Figure 5 This is a schematic diagram of the waterproof device of the present invention.

[0014] The attached diagram lists the components represented by each number as follows: 1. Slope protection piles; 2. Embedded plate; 3. Adjustable horizontal channel steel; 4. Main keel; 5. Secondary keel; 6. Multi-layer plywood; 7. High-strength cement composite board; 8. Waterproof guide wall for foundation slab; 9. Arc-shaped hole; 10. Channel steel body; 11. Precast rolled foam board; 12. Ground decorative board; 13. Flexible drainage channel; 14. Assembled arc-shaped plate; 15. Gravel filling layer; 16. Polyurea elastic pad; 17. Insertion hole; 18. V-shaped side groove. Detailed Implementation

[0015] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention. Example 1:

[0016] A BIM-based self-waterproof single-sided formwork system for basement exterior wall steel structure is used for construction within the trench formed between the slope protection pile 1 and the exterior wall of the basement foundation pit. The system includes: Multiple embedded plates 2 are fixed to the pile body of the slope protection pile 1 at intervals by expansion bolts. Specifically, the installation spacing of the embedded plates 2 along the vertical direction of the slope protection pile 1 is 450mm, and the arrangement spacing in the horizontal direction is 1500mm. Multiple adjustable horizontal channel steels 3, one end of which is vertically fixed to the embedded plate 2, and the other end extends horizontally into the channel. It can be further explained that the adjustable horizontal channel steel 3 is composed of two channel steel bodies 10 connected by bolts. One of the channel steels has an arc-shaped hole 9 on its side wall for adjusting the overlap length of the two channel steel bodies 10. The bolts pass through the arc-shaped hole 9 to fasten the two channel steel bodies 10. The main keel 4 is a horizontally set channel steel, which is fixedly connected to multiple adjustable horizontal channel steels 3 to form a transverse support frame. The vertical spacing between the main keels 4 is 450mm. Secondary keel 5 is a vertically arranged channel steel, which is fixed to the main keel 4 at intervals to form a vertical support frame. The horizontal spacing between secondary keels 5 is 300mm. Multi-layer plywood 6 is installed on the secondary keel 5 with self-tapping screws to form a template panel on the upper side of the waterproof guide wall 8 of the foundation slab. High-strength cement composite board 7 is installed in layers on the outer side of multi-layer plywood 6 using self-tapping screws, serving as a waterproof base layer.

[0017] The system also includes a flexible waterproofing system for basement roof slabs, which includes a precast roll foam board 11 laid on the roof slab, a flexible drainage channel 13 set on the foam board, an assembled arc plate 14 set on the upper side of the flexible drainage channel 13, a gravel filler layer 15 covering the flexible drainage channel 13 and the assembled arc plate 14, and a polyurea elastic pad 16. The flexible drainage channel 13 has V-shaped side channels 18 on both sides.

[0018] The precast foam board 11 has equidistant insertion holes 17 at one end and insertion rods at equidistant intervals at the other end. Multiple sets of precast foam boards 11 can be quickly assembled by inserting the insertion holes 17 and the insertion rods, which facilitates the laying of multiple sets of precast foam boards 11.

[0019] like Figures 1-5 As shown, a comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior steel structures based on BIM technology includes the following steps: Step 1: BIM Detailed Design and Construction Preparation Before construction, BIM technology should be used for full-process 3D modeling and clash detection. Key nodes such as embedded plate 2, keel, and waterproofing system should be designed in detail, layout optimized, and accurate material lists and construction drawings generated. For the external formwork of the basement exterior walls, materials and equipment required for formwork processing and installation should be prepared. After raw materials arrive at the construction site, they should be inspected under the supervision of the supervising engineer, and samples should be taken for re-inspection as required. Rain and moisture protection measures should be taken during on-site storage. All kinds of working machinery and tools should be complete, inspected, qualified, safe, and reliable, and all measuring tools should be calibrated. A construction schedule should be prepared before construction, and the number of laborers should be reasonably allocated according to the workload and schedule to organize construction in an orderly manner.

[0020] Step 2, Installation of Embedded Plate 2: Before constructing the waterproof guide wall 8 of the foundation slab, the base layer should be thoroughly cleaned, and the outer edge line of the wall should be marked out according to the construction drawings generated by BIM technology. During block construction, each block should be laid individually, using a full-lay and full-squeeze method. Mortar joints should be horizontal and vertical, and all joints should be fully filled with mortar. For vertical joints, mortar can be first applied to the end of the block, and then the block can be pressed onto the wall to the required dimensions. Inspections should be conducted regularly, with corrections made as construction progresses to avoid rework. After each block is completed, the mortar joints should be grouted until the construction of the waterproof guide wall 8 of the foundation slab is finished.

[0021] The installation of embedded plates 2 involves measuring and positioning them in a planar layout, followed by cleaning the area around the embedded plates 2 on the slope protection piles 1. The embedded plates 2 are then fixed to the slope protection piles 1 using expansion bolts, installed vertically along the slope protection piles 1. The vertical center-to-center distance between embedded plates 2 is 450mm, and the horizontal center-to-center distance is 1500mm. Additionally, if the position of the embedded plates 2 conflicts with the position of the steel beam, embedded plates 2 are added above and below the steel beam.

[0022] Step 3: Install the adjustable horizontal channel steel 3. Due to the unevenness of the slope protection pile 1, the lengths of the embedded plates 2 are different after installation. Therefore, the adjustable horizontal channel steel 3 is prefabricated in advance. Two channel steel bodies 10 are laterally provided with arc-shaped holes 9 and fixed with bolts, which can achieve the function of adjusting the spacing. Positioning measurement is carried out on the embedded plate 2 to determine the installation position of the adjustable horizontal channel steel 3. Select the adjustable horizontal channel steel 3. At the same time, in order to ensure that the adjustable horizontal channel steel 3 and the embedded plate 2 are firm enough during concrete pouring and are not affected by the self-side pressure of the concrete, one end of the adjustable horizontal channel steel 3 is fixed on the embedded plate 2 by means of double-sided full welding, and the weld height is not lower than the thickness of the steel plate. The other end is adjusted by bolts so that all the adjustable horizontal channel steels 3 are kept on the same horizontal plane vertically.

[0023] It can be supplemented that in order not to damage the steel bars of the slope protection pile 1, after the positioning of the embedded plate 2, it is fixed with expansion bolts, and the adjustable horizontal channel steel 3 is fixed on the embedded plate 2 by means of four-sided welding, and the weld height is not lower than the thickness of the steel plate; Due to the unevenness of the slope protection pile 1, the lengths of the embedded plates 2 are different after installation. Therefore, the adjustable horizontal channel steel 3 is prefabricated in advance. Two channel steel bodies 10 are laterally provided with arc-shaped holes 9 and fixed with bolts, which can achieve the function of adjusting the spacing; one end of the adjustable horizontal channel steel 3 is connected to the embedded plate 2 by double-sided full welding, and the other end is adjusted by bolts to be kept on the same horizontal plane vertically.

[0024] Step 4: Install the main and secondary keels 5: After the installation of the adjustable horizontal channel steel 3 is checked and found to be correct, select the cross keel of the channel steel main keel 4 to be fixed with the adjustable horizontal channel steel 3, and fix it by welding. The center distance of the cross keels is 450 mm. At the same time, in order to ensure that the welding quality reaches 100% qualified, the main keels 4 are welded to each other by means of four-sided full welding; after the installation of the main keel 4 is completed, the vertical keel of the channel steel secondary keel 5 is fixed to the main keel 4 by means of four-sided full welding, and the center distance of the vertical keels is 300 mm.

[0025] Step 5: Install the multi-layer plywood 6: When formwork is supported, in order to avoid problems that cannot be remedied due to the narrowness of the fat groove, 18 mm thick multi-layer plywood 6 is selected for the formwork, and then the multi-layer plywood 6 is nailed to the reserved holes of the channel steel secondary keel 5 with self-tapping screws. The formwork is fully paved, and the perpendicularity deviation is ±3 mm. All the formwork joints are qualified, and the joints are all tight and there is no offset. After the construction is completed, project personnel participate in the acceptance, and actual measurement is carried out to ensure that all the perpendicularity and formwork joints are qualified.

[0026] Step 6: Install the high-strength cement composite board 7: During construction, 12mm thick high-strength cement composite board 7 is first fixed to multi-layer plywood 6 using self-tapping screws. One layer of high-strength cement composite board 7 is installed first, followed by the pouring of impermeable concrete with added silica densifier. To ensure thorough vibration of the poured impermeable concrete, the high-strength cement composite board 7 is installed in layers, with the upper layer of high-strength cement composite board 7 installed after the lower layer of the top slab is poured. The high-strength cement composite board 7 and multi-layer plywood 6 are firmly fixed, all formwork joints are qualified and there are no misalignments. After each layer is constructed, the quality inspector inspects the installation quality of the high-strength cement composite board 7.

[0027] Step 7: Integrate the flexible waterproofing system for the roof slab; In the basement roof area, a flexible waterproofing system that combines rigidity and flexibility, and integrates prevention and drainage, is constructed. The flexible waterproofing system adopts a waterproofing device for basement anti-seepage construction disclosed in the authorization announcement number CN221142860U.

[0028] Specifically, step 7 includes the following steps: Step 701, Laying the base layer: The prefabricated roll foam board 11 with plug rods and plug holes 17 is quickly assembled and laid, and its internal vacuum cavity is used to achieve lightweight, waterproof, heat insulation and sound insulation.

[0029] Step 702: Install the drainage system: Install flexible drainage channels 13 on the prefabricated foam board 11. The V-shaped side channels 18 on both sides and the V-shaped bottom channel at the bottom are designed to effectively absorb the lateral and vertical deformation energy caused by earthquakes, etc., to prevent pipe bursts. Through the cooperation of the clips and slots, it is quickly assembled with the assembled arc plate 14 to form a closed-loop water supply network.

[0030] Step 703, Backfilling and Sealing: Fill the periphery of the hydrophobic system with a gravel filler layer 15 to adjust for uneven deformation. Then lay a polyurea elastic pad 16 with excellent toughness and waterproof performance.

[0031] Step 704: Complete the surface layer: Finally, assemble the floor decoration panel 12 using the assembly panels A and B with grooves and waterproof strips to complete the construction of the entire roof waterproofing system.

[0032] During construction, BIM technology can be fully utilized for construction simulation, pre-identifying spatial conflicts and safety risks in the installation of support systems and the hoisting paths of components, optimizing the construction sequence and work space layout, and conducting visual safety briefings.

[0033] This technical solution uses a detachable and recyclable steel structure to replace the traditional brick formwork, which not only reduces construction waste by more than 60%, but also significantly reduces dust emissions and noise pollution during construction, effectively improving the environmental quality of the surrounding area of ​​the construction site. At the same time, through standardized design and prefabricated construction, the proportion of on-site wet work is reduced by about 75%, significantly saving water resources and demonstrating good social and environmental benefits.

[0034] Taking the main structure and supporting construction of the Guiyang Evergrande Cultural Tourism City's No. 12 and No. 14 clusters as an example, under the same resource allocation and with similar numbers of labor teams and machinery, the traditional method takes an average of about 15 working days to complete the brickwork, plastering, curing, and subsequent construction conditions of approximately 100 linear meters of exterior wall on a single standard floor. This project, using this construction method, completed the installation of the embedded plate 2, the erection of the steel structure system, the installation of the high-strength cement composite board 7, and the overall acceptance of the same length of exterior wall, with an average time of approximately 10.2 working days. This technology successfully shortened the construction cycle by approximately 32%, which means that the construction cycle for a single standard floor was shortened by nearly 5 days. In terms of cost control, the main and secondary keels 5, horizontal channel steel, and other major steel structure components adopt standardized designs, are detachable, and reusable. According to project calculations, compared to the one-time investment in materials such as bricks and mortar, the steel structure system of this construction method, after being reused in three or more similar projects, has a lower amortized cost per use than the cost of traditional brick formwork materials. This achieves a long-term benefit of reducing material usage by approximately 40% when converted to a one-time investment. Although direct material costs may be roughly the same as or slightly higher than traditional processes, considering the reduced management costs due to time savings, improved capital efficiency, material turnover benefits, and reduced hidden costs due to improved quality, the overall project cost can be reduced by approximately 25%-30%, achieving significant economic benefits.

[0035] This construction method is mainly applied to the formwork construction of basement exterior walls. It adopts a steel structure support system to replace the traditional brick formwork construction, requiring less operating space and reducing construction processes such as masonry and plastering, thus speeding up the construction progress. At the same time, the steel structure formwork system is stable and unaffected by factors such as temperature, effectively ensuring construction quality. High-strength cement composite board 7 is used as a waterproof base layer combined with impermeable concrete to form a multi-layer combined waterproofing of the exterior wall. The waterproofing performance meets the construction requirements. The application effect of this method is good, solving the problems of long construction time, large space occupation, and high cost of traditional brick formwork construction, and it has strong applicability.

[0036] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A comprehensive construction process for a self-waterproofing single-sided formwork system for basement exterior steel structures based on BIM technology, characterized in that: Includes the following steps: Step 1, BIM detailed design and construction preparation: Use BIM technology to build a three-dimensional model, carry out detailed design and collision detection of embedded plate (2), main keel (4), secondary keel (5) and waterproof system, optimize layout and generate construction drawings and material list; Step 2, Installation of embedded plate (2): According to the BIM layout and positioning, clean the surface of the slope protection pile (1), and use expansion bolts to fix the embedded plate (2) on the slope protection pile (1) at the design spacing; Step 3: Install the adjustable horizontal channel steel (3): Weld one end of the prefabricated adjustable horizontal channel steel (3) to the embedded plate (2) on both sides, and adjust the length through its own arc hole (9) and bolts so that the ends of all adjustable horizontal channel steels (3) are kept on the same plane in the vertical direction. Step 4, Install the main and secondary keels (5): Weld the main keel (4) horizontally onto the adjustable horizontal channel steel (3), and then weld the secondary keel (5) vertically onto the main keel (4) to form a steel structure support frame; Step 5: Install plywood (6): Fix the plywood (6) to the secondary keel (5) with self-tapping screws; Step 6: Install high-strength cement composite board (7): First, install a layer of high-strength cement composite board (7) onto the multi-layer plywood (6), and then pour impermeable concrete with added silica densifier; after the concrete layer is poured, install the next layer of high-strength cement composite board (7) and continue to pour concrete, and repeat this cycle until the exterior wall construction is completed.

2. The integrated construction technology of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology as described in claim 1, characterized in that: Also includes: Step 7: Integrate the flexible waterproofing system for the roof slab; assemble precast roll foam boards (11) on the basement roof slab, install flexible drainage channels (13), backfill with gravel filler layer (15), lay polyurea elastic pads (16), and finally assemble the floor decorative panels.

3. The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology as described in claim 1, characterized in that: The vertical center distance between the two embedded plates (2) is 450mm, and the horizontal center distance is 1500mm.

4. The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology as described in claim 1, characterized in that: The center-to-center distance between the horizontal keels is 450mm, and the center-to-center distance between the vertical keels is 300mm.

5. The integrated construction process of the basement exterior wall steel structure self-waterproofing single-sided formwork system based on BIM technology as described in claim 1, characterized in that: The thickness of the multi-layer plywood (6) is 18 mm.

6. A self-waterproofing single-sided formwork system for basement exterior steel structures based on BIM technology, constructed using the construction process described in any one of claims 1-5, characterized in that: The BIM-based basement exterior wall steel structure self-waterproofing single-sided formwork system includes: Multiple embedded plates (2) are fixed to the pile body of the slope protection pile (1) at intervals by expansion bolts; Multiple adjustable horizontal channel steels (3) are fixedly connected at one end to the embedded plate (2) at the vertical direction, and at the other end extend into the trough in the horizontal direction; The main keel (4) is a horizontally set channel steel, which is fixedly connected to multiple adjustable horizontal channel steels (3) to form a transverse support frame; The secondary keel (5) is a vertically arranged channel steel, which is fixed at intervals on the main keel (4) to form a vertical support frame; Multi-layer plywood (6) is installed on the secondary keel (5) by self-tapping screws to form a template panel; High-strength cement composite board (7) is installed in layers on the outer side of the multi-layer plywood (6) using self-tapping screws as a waterproof base layer.

7. The BIM-based basement exterior wall steel structure self-waterproofing single-sided formwork system according to claim 6, characterized in that: The adjustable horizontal channel steel (3) is formed by connecting two channel steel bodies (10) with bolts. One of the channel steels has an arc-shaped hole (9) on its side wall for adjusting the overlap length of the two channel steels. The bolt passes through the arc-shaped hole (9) to fasten the two channel steels.

8. The BIM-based basement exterior wall steel structure self-waterproofing single-sided formwork system according to claim 6, characterized in that: It also includes a flexible waterproofing system for basement roof slabs, the flexible waterproofing system comprising a precast roll foam board (11) laid on the roof slab, a flexible drainage channel (13) set on the foam board, and a gravel filler layer (15) and a polyurea elastic pad (16) covering the periphery of the flexible drainage channel (13).

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