Process for sequential construction of basement exterior wall after construction of horizontal support changing structure through reverse construction method

Abstract

According to the technology, the horizontal support changing structures are sequentially constructed from top to bottom, in the process of constructing each layer of horizontal support changing structure, a guide wall of the basement outer wall is poured at the same time, a steel sleeve is pre-buried in the guide wall and used for pouring the outer wall, and the technology specifically comprises the following steps that S1, an enclosing purlin is constructed; s2, a horizontal support changing structure formwork is erected; s3, a first horizontal support changing structure is poured; s4, sequentially constructing a lower-layer horizontal support changing structure; s5, an outer wall formwork is constructed; s6, outer wall concrete is poured; the guide wall and the steel sleeve are reserved in advance to replace a traditional horn mouth to serve as an outer wall concrete pouring and vibrating channel, it is guaranteed that an outer wall reaches the top through one-time pouring, and the leakage hidden danger that due to the fact that the horn mouth space is narrow and cannot be vibrated in place, the contact position of new and old concrete is a honeycomb pitted surface, a dog hole and the like is avoided.

Description

Technical Field

[0001] The present application relates to the field of building construction, and specifically to a process for constructing a basement exterior wall by reverse construction of a horizontally replaced support structure followed by forward construction. Background Art

[0002] With the acceleration of the process of modern urban construction, more and more projects are springing up in the core areas of the city, resulting in the underground engineering piles of the buildings around the project being formed, and the foundation pits of the new construction sites do not have the conditions for anchor cable construction. From a cost perspective, the foundation pit support is usually designed in the form of steel lattice column diagonal bracing + double rows of support piles, and the reverse construction method is used to ensure structural safety. Different from the forward construction method, the reverse construction method requires the outer main structure beam and slab replacement support system to be constructed from top to bottom, and finally the exterior wall is constructed from bottom to top. The existing method of constructing the exterior wall is very likely to cause a large number of construction joints and cause leakage of the basement exterior wall structure. Summary of the invention

[0003] The purpose of the present invention is to provide a process for constructing the basement exterior wall in a forward manner after constructing the horizontal support structure by a reverse construction method, and constructing a basement exterior wall guide wall in advance. The guide wall has a size that exceeds the upper and lower structural surfaces of the beam and slab by 300 mm, and can provide a supporting surface for installing the basement exterior wall formwork. On the one hand, the verticality error of the basement exterior wall formwork installation in the later stage of the reverse construction method is reduced, and on the other hand, the top surface of the exterior wall concrete pouring is avoided at the inner corner of the wall and the slab, ensuring that the concrete is poured to the top in one time.

[0004] To achieve the above object, the present invention adopts the following technical solution: The process of constructing the basement exterior wall in a reverse construction method and then constructing the horizontal bracing structure in a sequential manner is characterized by: constructing the horizontal bracing structure in sequence from top to bottom, and in the process of constructing each layer of the horizontal bracing structure, pouring the guide wall of the basement exterior wall at the same time, and pre-buried steel casing in the guide wall for pouring the exterior wall, which specifically includes the following steps: S1, construction of purlin: planting reinforcement in the outer row of support piles for construction of purlin; S2, horizontal replacement support structure formwork: the first horizontal beam and slab replacement support and guide wall formwork are carried out, and a steel sleeve is reserved in the guide wall formwork. The steel sleeve is welded and fixed to the surrounding beam and slab steel bars. The steel sleeve serves as the pouring port, vibration port and air vent for the exterior wall concrete; S3, pouring the first horizontal replacement support structure: pouring the first horizontal beam-slab replacement support and guide wall. After the first horizontal beam-slab replacement support can normally bear the stress of the foundation pit side wall, remove the formwork and reinforcement materials, transport the first layer of earthwork, break the second row of temporary purlin piles and temporary steel diagonal braces, and the top surface of the second row of temporary purlin piles after breaking should be below the pre-constructed second horizontal beam-slab replacement support, and construct spray anchors; S4, sequentially construct the lower horizontal support replacement structure: from top to bottom, carry out the lower support replacement structure construction according to the above steps; after completing the process of removing the bottom support piles and diagonal supports and transporting the earthwork, carry out the construction of the basement floor; S5, construction of external wall formwork: chiseling of the joint surface of the guide wall and reinforcement of the bottom layer of external wall structure formwork; S6, pouring exterior wall concrete: pour exterior wall concrete along the steel casing, remove the formwork and maintain it before pouring the exterior wall of the upper layer, remove the formwork and maintain it before pouring the exterior wall of the upper layer. The remaining basement exterior walls are constructed in a bottom-up order until the exterior wall construction is completed.

[0005] Furthermore, step S1 specifically includes implanting a U-shaped steel bar with a diameter of 25mm in each of the upper and lower layers of the same supporting pile, with a depth of 650mm. When processing the steel bars, ensure that the total length of the U-shaped steel bars implanted in the first layer of purlin is not less than 2000mm, and the total length of the second layer is not less than 2400mm. The upper and lower layers of U-shaped steel bars are connected in series by hangers; the hangers include an upper tie portion, a middle connection portion and a lower bending portion, the upper tie portion is obliquely implanted into the outer row of supporting piles, the middle connection portion connects the two layers of U-shaped steel bars in series, and the lower bending portion is bent horizontally toward the outer row of supporting piles. During the process of completing the implantation of the U-shaped steel bars of the supporting piles to the start of the installation and binding of the purlin steel bars, the concrete surface in contact with the supporting piles and the replacement support structure is chiseled to ensure the effective connection between the new and old structures.

[0006] Furthermore, step S6 specifically includes checking whether all pre-buried steel casings are unobstructed before pouring begins, ensuring that the concrete can be normally vented and vibrated through the steel casings. During the pouring process, construction workers hold soft rubber hoses and extend them into the steel casings reserved on the guide wall to pour the exterior wall concrete, proceeding in sequence along the center direction of the exterior wall. The pouring height of each layer is ≤450mm to avoid extrusion and deformation of the exterior wall formwork due to excessive single concrete pouring height. In the gap between each layer of concrete pouring, the vibrator is extended into the casing to fully vibrate, thereby enhancing the tightness of the joint between the exterior wall and the guide wall after construction.

[0007] Furthermore, the exterior wall structure formwork includes a formwork body, wooden squares, vertical round steel bars and tension bolts, and the upper reserved steel bars and the lower reserved steel bars of the guide wall should both penetrate into the inner side of the formwork.

[0008] In addition, the guide wall size exceeds the upper and lower structural surfaces of the horizontal beam and slab support by 300mm.

[0009] More preferably, after the strength of each layer of the exterior wall reaches 80Mpa, the formwork is removed and the excess screws are cut off, the screw eyes are promptly handled, and the concrete surface is sprayed with water for maintenance. The remaining basement exterior walls are constructed in a bottom-up order, and the construction flow is organized according to the above steps. Finally, the entire basement structure is completed. During the process, the side walls of the foundation pit are in a safe support replacement state, which provides sufficient working space for construction personnel.

[0010] Compared with the prior art, the present invention has the following characteristics and beneficial effects: This application allows the removal of supporting structures such as steel diagonal braces in advance, reducing the large number of construction cold joints caused by the support diagonal braces penetrating the floor slab and exterior wall, greatly reducing the risk of leakage, and effectively saving the investment in water-stop steel plates, labor and maintenance costs; This application replaces the traditional "bell mouth" as the exterior wall concrete pouring and vibration channel by reserving guide walls and steel casing in advance, ensuring that the exterior wall is poured to the top in one go, avoiding honeycombed surfaces, dog holes and other leakage hazards at the contact points between new and old concrete due to the small space of the "bell mouth" that cannot be vibrated in place.

[0011] This application uniformly adjusts the exterior wall concrete pouring operation surface to the upper horizontal structural surface. Compared with the traditional construction method of leaving a "funnel" at the top of the wall for pouring, which creates safety risks such as high-altitude operations, it greatly improves the efficiency of concrete pouring and fully ensures construction safety.

[0012] Traditional construction methods are often limited by lighting, and on-site construction workers face great safety hazards due to insufficient lighting during work. In addition, since they work in a basement environment, there may be a large number of confined or narrow spaces. This method has a wide working surface, sufficient lighting or uses natural lighting, so the safety of construction workers can be fully guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram showing the relationship between the guide wall and the horizontal beam-slab replacement position in this application; Figure 2 This is a diagram showing the location of the guide wall formwork and steel casing for this application; Figure 3 This is a diagram showing the extension of the guide wall reinforcement involved in this application; Figure 4 It is a diagram of the purlin structure involved in this application; Figure 5 for Figure 4 Sectional view of part 1-1.

[0014] Figure numerals: 1-guide wall; 2-steel casing; 3-support piles; 4-purlin; 5-first horizontal beam-slab replacement support; 6-second row of temporary purlin piles; 7-temporary steel diagonal brace; 8-U-shaped steel bar; 9-hanger bar; 10-guide wall steel bar; 11-waterstop steel plate; 12-guide wall formwork. DETAILED DESCRIPTION

[0015] In order to make the technical means, innovative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

[0016] The embodiments described herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention, are illustrative and exemplary, and should not be construed as limiting the embodiments of the present invention and the scope of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the claims and the contents disclosed in the specification of this application, including technical solutions that adopt any obvious replacement and modification of the embodiments described herein.

[0017] The technology of constructing the basement exterior wall by reverse construction of the horizontal support structure and then constructing the basement exterior wall by forward construction, such as Figures 1 to 5 As shown, the main horizontal structure beam and slab of the underground main body is constructed in reverse order from top to bottom, and extended to the side of the supporting pile. By implanting double-layer "U"-shaped steel bars on the side wall of the supporting pile, it is anchored and connected with the extended horizontal structure beam and slab and cast into a whole to form a foundation pit replacement support structure; when constructing the horizontal structure replacement support, at the location of the basement outer wall, according to the requirements of the drawings, a part of the outer wall guide wall that exceeds the beam and slab by 300mm above and below is first constructed, and a group of DN110 steel casings are placed every 1m along the center line of the guide wall. This casing is used as the pouring port, vibration port, and ventilation port for the later pouring of the basement outer wall to ensure the compactness of the concrete pouring; the outer wall pouring is continuously pushed backward along one direction of the outer wall, and a pump pipe hose with a diameter of DN100 is selected. During the pouring process, the hose is inserted into the steel casing, and a vibrating rod is inserted into the adjacent casing to vibrate the concrete to ensure that the concrete is vibrated and compacted.

[0018] The method includes sequentially constructing a horizontal support structure from top to bottom. During the construction of each layer of the horizontal support structure, a guide wall 1 of the basement outer wall is poured simultaneously, and a steel casing 2 is pre-buried in the guide wall 1 for pouring the outer wall. The method specifically includes the following steps: S1, construction of purlin: planting reinforcement in the outer row of support piles 3 for construction of purlin 4; Step S1 specifically includes: implanting a U-shaped steel bar 8 with a diameter of 25mm in each of the upper and lower layers of the same supporting pile, with a depth of 650mm. When processing the steel bars, ensure that the total length of the U-shaped steel bars 8 implanted in the first layer of the surrounding purlin is not less than 2000mm, and the total length of the second layer is not less than 2400mm. The upper and lower layers of U-shaped steel bars 8 are connected in series by hanging bars 9; the hanging bars 9 include an upper tie-in portion, a middle connection portion and a lower bending portion. The upper tie-in portion is obliquely implanted into the outer row of supporting piles 3, the middle connection portion connects the two layers of U-shaped steel bars 8 in series, and the lower bending portion is bent horizontally toward the outer row of supporting piles 3. During the process of completing the planting of the U-shaped steel bars 8 of the supporting piles and starting the installation and binding of the surrounding purlin steel bars, the contact concrete surface between the supporting piles and the replacement support structure is chiseled to ensure the effective connection between the new and old structures; S2, horizontal replacement support structure formwork: the first horizontal beam and slab replacement support 5 and the guide wall 1 formwork, and reserve a steel sleeve 2 in the guide wall formwork 12, the steel sleeve 2 is welded and fixed to the surrounding beam and slab steel bars, and the steel sleeve 2 serves as the pouring port, vibration port and air vent of the exterior wall concrete; the size of the guide wall 1 exceeds the upper and lower structural surfaces of the horizontal beam and slab replacement support by 300mm respectively. In order to prevent the guide wall steel bars 10 and the water-stop steel plate 11 from rusting due to the humid underground environment, a layer of cement slurry needs to be brushed on in advance for protection.

[0019] S3, pouring the first horizontal replacement support structure: pouring the first horizontal beam-slab replacement support 5 and the guide wall 1. After the first horizontal beam-slab replacement support 5 can normally bear the stress of the foundation pit side wall, after removing the formwork and reinforcement materials, transporting the first layer of earthwork, breaking the second row of temporary purlin piles 6 and temporary steel diagonal braces 7, the top surface of the broken second row of temporary purlin piles 6 should be below the pre-constructed second horizontal beam-slab replacement support, and constructing spray anchors; S4, sequentially construct the lower horizontal support replacement structure: from top to bottom, carry out the lower support replacement structure construction according to the above steps; after completing the process of removing the bottom support piles and diagonal supports and transporting the earthwork, carry out the construction of the basement floor; S5, construct the external wall formwork: chisel the joint surface of the guide wall and reinforce the external wall structure formwork at the bottom layer; the external wall structure formwork includes a formwork body, wooden squares, vertical round steel and tension bolts, and the guide wall steel bars 10 reserved at the upper part of the guide wall 1 and the steel bars reserved at the lower part should be deep inside the formwork; S6, pouring exterior wall concrete: pour exterior wall concrete along steel casing 2, remove formwork and maintain, then pour the exterior wall of the upper layer, remove formwork and maintain, then pour the exterior wall of the upper layer, and the remaining basement exterior walls are constructed in a bottom-up order until the exterior wall construction is completed. Before pouring, check whether all pre-buried steel casings 2 are unblocked to ensure that the concrete can be normally vented and vibrated through the steel casings 2. During the pouring process, the construction personnel hold a soft hose and extend it into the steel casings 2 reserved on the guide wall 1 to pour the exterior wall concrete. The process is carried out in sequence along the center direction of the exterior wall. The pouring height of each layer is ≤450mm to avoid the extrusion and deformation of the exterior wall formwork due to the excessive height of a single concrete pouring. In the gap between each layer of concrete pouring, extend the vibrator into the casing to fully vibrate and enhance the tightness of the joint between the exterior wall and the guide wall after construction. After the strength of each layer of the exterior wall reaches 80Mpa, remove the formwork and cut off the excess screws, deal with the screw eyes in time, and sprinkle water on the concrete surface for maintenance. The remaining basement exterior walls are constructed in a bottom-up order and the construction flow is organized according to the above steps. Finally, the entire basement structure construction is completed. During the process, the side walls of the foundation pit are in a safe support replacement state, which provides sufficient working space for the construction personnel.

[0020] The specific steps of this application are as follows: 1. Construction of supporting pile reinforcement Before construction, the drawings should be reviewed to compare and analyze the support form and the distribution of steel bars in each layer of purlins, walls and beams and slabs. The gap between the steel bars that need to be overlapped should not be greater than 5mm.

[0021] One U-shaped HRB400 steel bar with a diameter of 25mm is implanted in each of the upper and lower layers of the same support pile, and the implant depth is 650mm. When processing the steel bars, ensure that the total length of the U-shaped steel bars implanted in the first layer of the purlin is not less than 2000mm, and the total length of the second layer is not less than 2400mm.

[0022] During the process of completing the U-shaped reinforcement planting of the supporting piles and starting the installation and binding of the surrounding purlin reinforcement, the concrete surface in contact with the supporting piles and the replacement support structure is chiseled to ensure the effective connection between the new and old structures.

[0023] 2. Replace the support formwork for the horizontal beam and slab and reserve steel casing After the installation process of the horizontal beam and slab replacement reinforcement is completed, the formwork is installed in a top-down construction sequence. Before installing the formwork, a layer of release agent must be applied on its surface, and the installation verticality error must be controlled to be ≤±4mm to ensure that the concrete pouring surface is smooth and flat for easy demoulding. During the construction process, a DN110 steel casing is pre-buried at intervals of 1m along the center line of the exterior wall and welded to the surrounding reinforcement. Later, it will replace the traditional "trumpet" as the pouring port, vibration port and air vent of the exterior wall concrete.

[0024] 3. Casting horizontal support beams and external wall guide walls While constructing the horizontal replacement support structure beam and slab reinforcement and formwork, a basement exterior wall guide wall is constructed in advance. After research and analysis, the size of the guide wall exceeds the upper and lower structural surfaces of the beam and slab by 300mm, which can provide a supporting surface for the installation of the basement exterior wall formwork. On the one hand, it reduces the verticality error of the basement exterior wall formwork installation in the later stage of the reverse construction method, and on the other hand, it avoids the top surface of the exterior wall concrete pouring at the inner corner of the wall and slab, ensuring that the concrete is poured to the top in one time. In order to prevent the guide wall reinforcement and water-stop steel plate from rusting due to the humid underground environment, it is necessary to brush a layer of cement slurry in advance for protection.

[0025] 4. Remove the inner row of support piles and steel diagonal braces After the first beam and slab replacement support can normally bear the stress of the foundation pit side wall, after removing the formwork and reinforcement materials, the first layer of earth is transported out; the second row of temporary purlin piles and temporary steel diagonal braces are broken, spray anchors are constructed, and the second replacement support structure construction process is carried out according to the above steps. After the structural strength reaches the design requirements, the bottom layer of supporting piles and diagonal braces are broken and the earth is transported out, and finally the tower raft slab is constructed.

[0026] 5. Chisel the joint surface of the guide wall and reinforce the external wall structure template Before installing the exterior wall formwork, the concrete joints of the guide wall completed in the previous construction were roughened to expose the gravel surface and increase the compactness of the new and old concrete. In addition, to further reduce the risk of leakage, M18 water stop screws were used to reinforce the exterior wall formwork at a spacing of 600mm (horizontally) × 800mm (vertically).

[0027] 6. Pour exterior wall concrete along the steel casing Install a DN100 diameter soft hose at the end of the concrete placing machine. Before pouring, check whether all pre-buried DN110 steel casings are unblocked to ensure that the concrete can be normally vented and vibrated through the casing. During the pouring process, construction workers hold soft hoses and extend them into the steel casing reserved on the guide wall to pour the exterior wall concrete, one by one along the center direction of the exterior wall. The pouring height of each layer is ≤450mm to avoid extrusion and deformation of the exterior wall formwork due to excessive height of a single concrete pouring. In the gap between each layer of concrete pouring, extend the vibrator into the casing to fully vibrate and enhance the tightness of the joint between the exterior wall and the guide wall after construction.

[0028] 7. After removing the mold and curing, pour the upper layer of the exterior wall After the strength of each layer of the exterior wall reaches 80Mpa, the formwork is removed and the excess screws are cut off, the screw holes are handled in time, and the concrete surface is sprayed with water for maintenance. The remaining basement exterior walls are constructed in a bottom-up order, and the construction flow is organized according to the above steps, and finally the entire basement structure construction is completed. During the process, the side walls of the foundation pit are in a safe support replacement state, which not only provides sufficient working space for the construction workers, but also avoids the occurrence of difficult-to-handle quality problems such as "bell mouth".

[0029] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for constructing the basement exterior wall by reverse construction of the horizontal support structure and then by forward construction, characterized by: The horizontal support structure is constructed sequentially from top to bottom. During the construction of each layer of the horizontal support structure, the guide wall (1) of the basement outer wall is poured at the same time, and a steel casing (2) is embedded in the guide wall (1) for pouring the outer wall. The steps specifically include: S1, construction of the perimeter purlin: planting reinforcement bars in the outer row of support piles (3) for construction of the perimeter purlin (4); S2, horizontal replacement support structure formwork: the first horizontal beam and slab replacement support (5) and the guide wall (1) formwork, and a steel sleeve (2) is reserved in the guide wall support formwork (12), the steel sleeve (2) is welded and fixed to the surrounding beam and slab steel bars, and the steel sleeve (2) serves as the pouring port, vibration port and air vent of the exterior wall concrete; S3, pouring the first horizontal replacement support structure: pouring the first horizontal beam-slab replacement support (5) and the guide wall (1), after the first horizontal beam-slab replacement support (5) can normally bear the stress of the foundation pit side wall, after removing the formwork and reinforcement materials, transporting the first layer of earthwork, breaking the second row of temporary purlin piles (6) and temporary steel diagonal braces (7), the top surface of the broken second row of temporary purlin piles (6) should be below the pre-constructed second horizontal beam-slab replacement support, and constructing spray anchors; S4, sequentially construct the lower horizontal support replacement structure: from top to bottom, carry out the lower support replacement structure construction according to the above steps; after completing the process of removing the bottom support piles and diagonal supports and transporting the earthwork, carry out the construction of the basement floor; S5, construction of external wall formwork: chiseling of the joint surface of the guide wall and reinforcement of the bottom layer of external wall structure formwork; S6, pouring exterior wall concrete: pouring exterior wall concrete along the steel casing (2), removing the formwork and curing, and then pouring the exterior wall of the upper layer, and then pouring the exterior wall of the upper layer after removing the formwork and curing. The remaining basement exterior walls are constructed in a bottom-up construction sequence until the exterior wall construction is completed.

2. The process of constructing the basement exterior wall by reverse construction of the horizontal support structure and then sequential construction as claimed in claim 1, characterized in that: Step S1 specifically comprises: implanting a U-shaped steel bar (8) with a diameter of 25 mm in each of the upper and lower layers of the same supporting pile, with a depth of 650 mm; during the steel bar processing, ensuring that the total length of the U-shaped steel bars (8) implanted in the first layer of the surrounding purlin is not less than 2000 mm, and the total length of the second layer is not less than 2400 mm; the upper and lower layers of the U-shaped steel bars (8) are connected in series by a hanger bar (9); the hanger bar (9) comprises an upper tie-in portion, a middle connection portion and a lower bending portion; the upper tie-in portion is implanted obliquely upward into the outer row of supporting piles (3); the middle connection portion connects the two layers of U-shaped steel bars (8) in series; the lower bending portion is bent horizontally toward the outer row of supporting piles (3); during the process of completing the implantation of the U-shaped steel bars (8) in the supporting piles and starting the installation and binding of the surrounding purlin steel bars, the contact concrete surface between the supporting piles and the replacement support structure is chiseled to ensure the effective connection between the new and old structures.

3. The process of constructing the basement exterior wall by reverse construction of the horizontal support structure and then sequential construction as claimed in claim 1, characterized in that: Step S6 specifically includes, before pouring, checking whether all pre-buried steel sleeves (2) are unblocked, ensuring that the concrete can be normally vented and vibrated through the steel sleeves (2); during pouring, the construction personnel hold a soft hose and extend it into the steel sleeves (2) reserved on the guide wall (1) to pour the exterior wall concrete, and do so in sequence along the center direction of the exterior wall. The pouring height of each layer is ≤450mm, so as to avoid the compression and deformation of the exterior wall formwork caused by excessive height of a single concrete pouring. In the interval between pouring each layer of concrete, a vibrating rod is extended into the sleeve to fully vibrate, so as to enhance the tightness of the joint between the exterior wall and the guide wall after construction.

4. The process of constructing the basement exterior wall by reverse construction of the horizontal support structure and then sequential construction as claimed in claim 1, characterized in that: The external wall structure template comprises a template body, wooden squares, vertical round steel and tension bolts, and the upper reserved guide wall steel bars (10) and the lower reserved steel bars of the guide wall (1) should both penetrate deep into the inner side of the template.

5. The process of constructing the basement exterior wall by reverse construction of the horizontal support structure and then by sequential construction as claimed in claim 1, characterized in that: The size of the guide wall (1) exceeds the upper and lower structural surfaces of the horizontal beam-slab replacement support by 300 mm. In order to prevent the guide wall steel bars (10) and the water-stop steel plate (11) from rusting due to the humid underground environment, a layer of cement slurry is applied in advance for protection.

6. The process of constructing the basement exterior wall by reverse construction of the horizontal support structure and then sequential construction as claimed in claim 1, characterized in that: After the strength of each layer of exterior wall reaches 80Mpa, the formwork is removed and the excess screws are cut off, the screw holes are handled in time, and the concrete surface is sprayed with water for maintenance. The remaining basement exterior walls are constructed in a bottom-up order, and the construction flow is organized according to the above steps. Finally, the entire basement structure construction is completed. During the process, the side walls of the foundation pit are in a safe support replacement state, which provides sufficient working space for construction personnel.

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