Technique for constructing basement outer wall after horizontal bracing structure of top-down method construction

Abstract

The process of top-down construction of basement outer wall after construction of horizontal bracing structure by reverse construction method, sequentially constructs the horizontal bracing structure from top to bottom, simultaneously pours the guide wall of the basement outer wall during the construction of each layer of horizontal bracing structure, and pre-buries the steel sleeve in the guide wall for pouring the outer wall, specifically comprising the following steps: S1, construction of surrounding purlin; S2, horizontal bracing structure formwork; S3, pouring the first horizontal bracing structure; S4, sequentially constructing the lower horizontal bracing structure; S5, construction of outer wall formwork; S6, pouring of outer wall concrete; the application replaces the traditional "horn mouth" as the pouring and vibrating channel of the outer wall concrete by reserving the guide wall and steel sleeve in advance, ensures that the outer wall is poured to the top at one time, avoids the narrow space of the "horn mouth" from causing the new and old concrete contact part to be not vibrated in place, and causes the leakage hidden danger of honeycomb and dog hole of the old concrete.

Description

Technical Field

[0001] This application relates to the field of building construction, specifically to the process of constructing basement exterior walls using the reverse construction method followed by the forward construction method for a horizontally braced structure. Background Technology

[0002] With the rapid pace of modern urban construction, more and more projects are springing up in the city center, resulting in the existing underground engineering piles of surrounding buildings already in place, leaving new construction sites without the conditions for anchor cable construction. From a cost perspective, foundation pit support is typically designed as a steel lattice column bracing system with double-row support piles, using a reverse construction method to ensure structural safety. Unlike the forward construction method, the reverse construction method requires constructing the outer main structural beam and slab replacement bracing system from top to bottom, and finally constructing the exterior walls from bottom to top. Existing methods for constructing exterior walls easily create numerous construction joints, leading to structural leakage in the basement exterior walls. Summary of the Invention

[0003] The purpose of this invention is to provide a process for constructing basement exterior walls using the reverse construction method followed by the forward construction method. A basement exterior wall guide wall is constructed in advance, with the guide wall extending 300mm beyond the upper and lower structural surfaces of the beams and slabs. This guide wall provides a support surface for the installation of the basement exterior wall formwork. On the one hand, this reduces the verticality error of the basement exterior wall formwork installation in the later stages of the reverse construction method. On the other hand, it avoids the top surface of the exterior wall concrete pouring being at the inside corner of the wall and slab, ensuring that the concrete is poured to the top in one go.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The process of constructing the basement exterior wall using the reverse construction method followed by the sequential construction method is characterized by: constructing the horizontal support structure sequentially from top to bottom; simultaneously pouring guide walls for the basement exterior wall during the construction of each floor's horizontal support structure; and pre-embedding steel sleeves within the guide walls for pouring the exterior wall. Specifically, it includes the following steps:

[0006] S1, Construction waler: Reinforcing bars are installed on the outer row of support piles for construction walers;

[0007] S2, Horizontal replacement support structure formwork: the first horizontal beam and slab replacement support and guide wall formwork, and a steel sleeve is reserved in the guide wall formwork. The steel sleeve is welded and fixed to the surrounding beam and slab reinforcement. The steel sleeve serves as the pouring port, vibration port and ventilation hole for the external wall concrete.

[0008] S3, pour the first horizontal support structure: pour the first horizontal beam-slab support and guide wall. After the first horizontal beam-slab support can normally bear the stress of the foundation pit sidewall, remove the formwork and reinforcement materials, transport the first layer of soil, break the second row of temporary waler piles and temporary steel diagonal braces. The top surface of the second row of temporary waler piles after breaking should be below the pre-constructed second horizontal beam-slab support. Shotcrete and anchoring are then carried out.

[0009] S4, Sequential construction of the lower-level horizontal support structure: From top to bottom, carry out the construction of the lower-level support structure according to the above steps; after completing the bottom support piles, diagonal brace removal and earthwork removal, carry out the construction of the basement floor slab;

[0010] S5, Construction of exterior wall formwork: chiseling and reinforcing the bottom layer of exterior wall structure formwork at the guide wall joint surface;

[0011] S6, pouring exterior wall concrete: pour exterior wall concrete along the steel sleeve, and after demolding and curing, pour the exterior wall of the next floor. After demolding and curing, pour the exterior wall of the next floor. The remaining basement exterior walls are constructed in a bottom-up construction sequence until the exterior wall construction is completed.

[0012] Further, step S1 specifically includes: inserting one U-shaped steel bar with a diameter of 25mm into each of the upper and lower layers of the same support pile, with a planting depth of 650mm. During steel bar processing, ensure that the total length of the U-shaped steel bars inserted into the first layer of walers 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 a hanger bar. The hanger bar includes an upper tie part, a middle connecting part, and a lower bending part. The upper tie part is inserted obliquely upward into the outer row of support piles, the middle connecting part connects the two layers of U-shaped steel bars in series, and the lower bending part bends horizontally towards the outer row of support piles. During the process from completing the planting of the U-shaped steel bars of the support pile to starting the installation and binding of the waler steel bars, the concrete surface in contact between the support pile and the replacement structure is chiseled to ensure an effective connection between the old and new structures.

[0013] Furthermore, step S6 specifically includes checking whether all pre-embedded steel sleeves are unobstructed before pouring begins, ensuring that the concrete can be properly vented and vibrated through the steel sleeves. During the pouring process, construction workers hold soft rubber hoses and insert them into the steel sleeves reserved on the guide wall to pour the exterior wall concrete, proceeding sequentially along the center of the exterior wall. The pouring height of each layer is ≤450mm to avoid deformation of the exterior wall formwork due to excessive single concrete pouring height. During the interval between each layer of concrete pouring, a vibrator is inserted into the sleeve to fully vibrate, enhancing the tightness of the joint between the subsequently constructed exterior wall and the guide wall.

[0014] Furthermore, the external wall structure formwork includes the formwork body, timber, vertical round steel and tie bolts, and the upper and lower reserved reinforcing bars of the guide wall should extend into the inside of the formwork.

[0015] In addition, the guide wall dimensions exceed the upper and lower structural surfaces of the horizontal beam-slab replacement support by 300mm each.

[0016] More preferably, after the strength of each floor's exterior wall reaches 80 MPa, the formwork is removed and excess bolts are cut off. The bolt holes are then cleaned promptly, and the concrete surface is watered for curing. The remaining basement exterior walls are constructed in a bottom-up sequence, and the construction flow is organized according to the above steps. Finally, the entire basement structure is completed. During the process, the foundation pit sidewalls are in a safe support replacement state, providing ample working space for the construction workers.

[0017] Compared with the prior art, the present invention has the following features and beneficial effects:

[0018] This application allows for the early removal of steel bracing and other support structures, reducing the large number of cold joints caused by the bracing penetrating the floor slab and exterior wall, greatly reducing the risk of leakage, and effectively saving on the investment of waterstop steel plates, labor and maintenance costs.

[0019] This application replaces the traditional "flared opening" as the channel for pouring and vibrating concrete in the exterior wall by pre-reserving guide walls and steel sleeves, ensuring that the exterior wall is poured to the top in one go, and avoiding the leakage risks such as honeycomb, pitting, and dog holes at the contact point of new and old concrete caused by the narrow space of the "flared opening" which cannot be vibrated in place.

[0020] This application adjusts the concrete pouring surface of the exterior wall to the upper horizontal structural surface. Compared with the traditional construction method of leaving a "flared" position at the top of the wall for pouring, which causes safety risks such as working at height, this application greatly improves the efficiency of concrete pouring and fully ensures construction safety.

[0021] Traditional construction methods often suffer from insufficient lighting due to limited natural light, posing significant safety hazards to on-site workers. Furthermore, working in basement environments can lead to numerous enclosed or confined spaces. In contrast, this method offers a wide working area with ample lighting or the use of natural light, ensuring the safety of construction workers. Attached Figure Description

[0022] Figure 1 This is a diagram showing the positional relationship between the guide wall and the horizontal beam / slab support in this application;

[0023] Figure 2 This is a diagram showing the relationship between the guide wall formwork and the steel sleeve position in this application;

[0024] Figure 3 The diagram shows the extension of the guide wall reinforcement involved in this application;

[0025] Figure 4 This is a diagram illustrating the waler structure involved in this application;

[0026] Figure 5 for Figure 4 Sectional view of part 1-1.

[0027] Attached reference numerals: 1-Guide wall; 2-Steel sleeve; 3-Support pile; 4-Wallet; 5-First horizontal beam and slab replacement support; 7-Temporary steel diagonal brace; 8-U-shaped steel bar; 9-Hanging bar; 10-Guide wall reinforcement; 11-Waterstop steel plate; 12-Guide wall formwork. Detailed Implementation

[0028] To make the technical means, innovative features, objectives and effects of this invention easier to understand, the invention will be further described below.

[0029] The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the invention, and are illustrative and exemplary, and should not be construed as limiting the implementation or scope of the invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0030] The process of constructing the basement exterior walls using the reverse construction method followed by the forward construction method, such as... Figures 1-5 As shown, the underground main structure horizontal beams and slabs are constructed sequentially from top to bottom in reverse order, extending to the edge of the support piles. Double-layered "U"-shaped steel bars are embedded in the sidewalls of the support piles, anchored to the extended horizontal beams and slabs, and cast as a whole to form the foundation pit support structure. During the construction of the horizontal support structure, at the location of the basement exterior wall, a section of the exterior wall guide wall extending 300mm above and below the beams and slabs is constructed according to the drawings. A set of DN110 steel sleeves is placed every 1m along the centerline of the guide wall. These sleeves serve as the pouring port, vibration port, and ventilation port for the later pouring of the basement exterior wall, ensuring the compactness of the concrete pouring. The exterior wall pouring continues backward in one direction, using a DN100 diameter pump hose. During the pouring process, the hose is inserted into the steel sleeve, and simultaneously, a vibrator is inserted into adjacent sleeves to vibrate the concrete, ensuring its compaction.

[0031] The construction includes the sequential construction of horizontal support structures from top to bottom. During the construction of each floor's horizontal support structure, the guide wall 1 of the basement exterior wall is simultaneously poured, and a steel sleeve 2 is pre-embedded in the guide wall 1 for pouring the exterior wall. The specific steps include:

[0032] S1, Construction waler: Reinforcing bars are installed on the outer row of support piles 3 for the construction waler 4;

[0033] Step S1 specifically includes: inserting one U-shaped steel bar 8 with a diameter of 25mm into each of the upper and lower layers of the same support pile, with a planting depth of 650mm. During steel bar processing, ensure that the total length of the U-shaped steel bars 8 inserted into the first layer of walers 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 a hanger 9. The hanger 9 includes an upper tie part, a middle connecting part and a lower bending part. The upper tie part is inserted obliquely upward into the outer row of support piles 3, the middle connecting part connects the two layers of U-shaped steel bars 8 in series, and the lower bending part bends horizontally towards the outer row of support piles 3. During the process from the completion of the planting of the U-shaped steel bars 8 of the support pile to the start of the installation and binding of the waler steel bars, the concrete surface in contact with the support pile and the replacement structure is chiseled to ensure the effective connection between the old and new structures.

[0034] S2, Horizontal replacement support structure formwork: The first horizontal beam and slab replacement support 5 and guide wall 1 formwork are supported, and a steel sleeve 2 is reserved in the guide wall formwork 12. The steel sleeve 2 is welded and fixed to the surrounding beam and slab reinforcement. The steel sleeve 2 serves as the pouring port, vibration port and ventilation hole for the external wall concrete. The guide wall 1 extends 300mm above and below the horizontal beam and slab replacement support structure. To prevent the guide wall reinforcement 10 and water-stop steel plate 11 from rusting due to the underground humid environment, a layer of cement slurry needs to be applied in advance for protection.

[0035] S3, pour the first horizontal replacement support structure: pour the first horizontal beam-slab replacement support 5 and guide wall 1. After the first horizontal beam-slab replacement support 5 can normally bear the stress of the foundation pit sidewall, remove the formwork and reinforcement materials, transport the first layer of soil, break the second row of temporary waler piles and temporary steel diagonal bracing 7. The top surface of the second row of temporary waler piles after breaking should be below the pre-constructed second horizontal beam-slab replacement support, and carry out shotcrete construction.

[0036] S4, Sequential construction of the lower-level horizontal support structure: From top to bottom, carry out the construction of the lower-level support structure according to the above steps; after completing the bottom support piles, diagonal brace removal and earthwork removal, carry out the construction of the basement floor slab;

[0037] S5, Construction of exterior wall formwork: chiseling and reinforcing the bottom layer of exterior wall structure formwork at the guide wall joint surface; the exterior wall structure formwork includes the formwork body, timber, vertical round steel and tie bolts, and the upper and lower reserved guide wall steel bars 10 of the guide wall 1 should both extend into the inside of the formwork;

[0038] S6, pouring exterior wall concrete: pour exterior wall concrete along steel sleeve 2, after demolding and curing, pour the exterior wall of the next floor, after demolding and curing, pour the exterior wall of the next floor, and so on. The remaining basement exterior walls are constructed in the order of bottom to top until the exterior wall construction is completed. Before pouring begins, check that all pre-embedded steel sleeves 2 are unobstructed to ensure that the concrete can be properly vented and vibrated through the steel sleeves 2. During the pouring process, construction workers hold soft rubber hoses and insert them into the steel sleeves 2 pre-installed on the guide wall 1 to pour the exterior wall concrete, proceeding sequentially along the center of the exterior wall. The pouring height of each layer should be ≤450mm to avoid deformation of the exterior wall formwork due to excessive pouring height in a single pour. During the intervals between each layer of concrete pouring, insert a vibrator into the sleeve to fully vibrate and enhance the tightness of the joint between the exterior wall and the guide wall. After each layer of exterior wall reaches a strength of 80Mpa, remove the formwork and cut off excess bolts, promptly treat the bolt holes, and water the concrete surface for curing. The remaining basement exterior walls are constructed in a bottom-up sequence, 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 state, providing ample working space for the construction workers.

[0039] The specific steps for this application are as follows:

[0040] 1. Construction of support piles and rebar installation

[0041] Before construction, the drawings should be reviewed and analyzed to compare the support form and the distribution of steel bars in the walers, walls and beams of each floor. The gap between steel bars that need to be lapped should not be greater than 5mm.

[0042] For each support pile, one 25mm diameter "U"-shaped HRB400 steel bar is inserted in the upper and lower layers, with a insertion depth of 650mm. During steel bar processing, ensure that the total length of the "U"-shaped steel bars inserted in the first layer of walers is not less than 2000mm, and the total length of the second layer is not less than 2400mm.

[0043] From the completion of the U-shaped steel bar installation of the support piles to the start of the waler steel bar installation and binding process, the concrete surface in contact between the support piles and the replacement structure is chiseled to ensure an effective connection between the old and new structures.

[0044] 2. Replace the formwork for horizontal beams and slabs and reserve steel sleeves.

[0045] After the installation of the horizontal beam and slab reinforcement bars is completed, the formwork is installed in a top-down construction sequence. Before installation, a layer of release agent is applied to the surface of the formwork, and the verticality error is controlled to be ≤±4mm to ensure a smooth and flat concrete pouring surface for easy demolding. During construction, a DN110 steel sleeve is pre-embedded every 1m along the centerline of the exterior wall and welded to the surrounding reinforcement bars. This sleeve will later replace the traditional "flared opening" as the pouring port, vibration port, and ventilation hole for the exterior wall concrete.

[0046] 3. Casting horizontal replacement beams and slabs and external guide walls.

[0047] While constructing the horizontal support structure beams and slabs, reinforcing steel and formwork, a basement exterior wall guide wall is constructed in advance. Research and analysis show that the guide wall extends 300mm beyond the upper and lower structural surfaces of the beams and slabs, providing a support surface for the basement exterior wall formwork installation. This reduces the verticality error of the basement exterior wall formwork installation in the later stages of the reverse construction method, and avoids the top surface of the exterior wall concrete pouring being at the inside corner of the wall and slab, ensuring that the concrete is poured to the top in one go. To prevent the guide wall reinforcement and water-stop steel plate from rusting due to the damp underground environment, a layer of cement slurry needs to be applied in advance for protection.

[0048] 4. Demolish the inner row of retaining piles and steel diagonal braces.

[0049] After the first beam-slab replacement support can normally bear the stress of the foundation pit sidewall, the formwork and reinforcement materials are removed, and the first layer of soil is transported out. The second row of temporary waler piles and temporary steel diagonal braces are broken, and shotcrete and anchor are constructed. The second replacement support structure construction process is carried out in accordance with the above steps. After the structural strength reaches the design requirements, the bottom layer of support piles, diagonal brace breaking and soil transportation are completed. Finally, the tower top raft slab is constructed.

[0050] 5. Chiseling and reinforcing the joint surface of the guide wall and the external wall structure formwork.

[0051] Before installing the exterior wall formwork, the concrete joint surfaces of the previously constructed guide walls are roughened to expose the aggregate surface, increasing the density of the bond between the old and new concrete. In addition, to further reduce the risk of leakage, M18 water-stop bolts are used to reinforce the exterior wall formwork at a spacing of 600mm (horizontal) × 800mm (vertical).

[0052] 6. Pour the exterior wall concrete along the steel sleeve.

[0053] Install a DN100 diameter flexible hose at the end of the concrete placing boom. Before pouring, check that all pre-embedded DN110 steel sleeves are clear to ensure that the concrete can pass through the sleeves for proper air venting and vibration. During pouring, workers hold the flexible hose and insert it into the steel sleeves pre-installed on the guide wall to pour the exterior wall concrete, proceeding sequentially along the center of the exterior wall. Each layer should be ≤450mm high to avoid deformation of the exterior wall formwork due to excessive pouring height in a single operation. During the intervals between each concrete pour, insert a vibrator into the sleeve for thorough compaction to enhance the tightness of the joint between the constructed exterior wall and the guide wall.

[0054] 7. After demolding and curing, pour the next layer of exterior wall.

[0055] After each floor's exterior wall reached a strength of 80 MPa, the formwork was removed, excess bolts were cut off, bolt holes were promptly cleaned, and the concrete surface was water-cured. The remaining basement exterior walls were constructed in a bottom-up sequence, following the above steps in a construction flow, ultimately completing the entire basement structure. Throughout the process, the foundation pit sidewalls were kept in a safe support replacement state, providing ample working space for construction workers and avoiding difficult-to-handle quality problems such as "flared ends."

[0056] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction process for basement exterior walls using the reverse construction method followed by the forward construction method after the horizontal support replacement structure, characterized by: The horizontal support changing structure is sequentially constructed from top to bottom, and the guide wall (1) of the basement outer wall is simultaneously poured during the construction of each layer of the horizontal support changing structure, and a steel sleeve (2) is embedded in the guide wall (1) for pouring the outer wall, and the method comprises the following steps: S1, construction of the surrounding purlin: the external row support pile (3) is planted with a U-shaped steel bar (8) with a diameter of 25 mm for the construction of the surrounding purlin (4); The step S1 specifically comprises that one U-shaped steel bar (8) with a diameter of 25 mm is planted in each of the upper and lower two layers of the same support pile, the planting depth is 650 mm, the total length of the U-shaped steel bar (8) planted in the first layer of the surrounding purlin is ensured to be not less than 2000 mm, the total length of the U-shaped steel bar (8) planted in the second layer is ensured to be not less than 2400 mm, and the U-shaped steel bars (8) in the upper and lower two layers are connected by a hanging steel bar (9); the hanging steel bar (9) comprises an upper tie-up portion, a middle connecting portion and a lower bending portion, the upper tie-up portion is planted in the external row support pile (3) in a slanting upward direction, the middle connecting portion connects the two layers of U-shaped steel bars (8), and the lower bending portion is bent horizontally to the external row support pile (3); during the process of completing the U-shaped steel bar (8) planting of the support pile to the installation and binding of the surrounding purlin steel bar, the concrete surface of the support pile in contact with the support changing structure is chiseled and gouged to ensure the effective connection between the new and old structures; S2, support of the horizontal support changing structure: the first horizontal beam plate support changing structure (5) and the guide wall (1) are supported, and the steel sleeve (2) is reserved in the guide wall support (12), the steel sleeve (2) is welded and fixed with the surrounding beam plate steel bar, and the steel sleeve (2) serves as the pouring opening, the vibrating opening and the air vent hole of the outer wall concrete; S3, pouring of the first horizontal support changing structure: the first horizontal beam plate support changing structure (5) and the guide wall (1) are poured, after the first horizontal beam plate support changing structure (5) can normally bear the stress of the side wall of the foundation pit, the size of the guide wall (1) exceeds the upper and lower structure surfaces of the horizontal beam plate support changing structure by 300 mm, the formwork and the reinforcing material are removed, the first layer of earthwork is transported out, the second row of temporary surrounding purlin piles and the temporary steel inclined braces (7) are broken, the top surface of the broken second row of temporary surrounding purlin piles should be below the pre-constructed second horizontal beam plate support changing structure, and the jet anchor is constructed; S4, sequential construction of the lower horizontal support changing structure: the lower support changing structure is sequentially constructed from top to bottom according to the above steps; after the process of breaking the support pile, the inclined brace and transporting out the earthwork of the bottom layer is completed, the construction of the basement bottom plate is performed; S5, construction of the outer wall formwork: the guide wall joint surface is chiseled and gouged, and the formwork of the outer wall structure of the bottom layer is reinforced; S6, pouring of the outer wall concrete: the outer wall concrete is poured along the steel sleeve (2), the outer wall of the upper layer is poured after the formwork is removed and maintained, the outer wall of the upper layer is poured after the formwork is removed and maintained, and the remaining basement outer wall is sequentially constructed from bottom to top until the construction of the outer wall is completed.

2. The process for constructing basement exterior wall by top-down method after constructing horizontal bracing structure by bottom-up method according to claim 1, wherein: The step S6 specifically comprises: checking whether all embedded steel sleeves (2) are unblocked before pouring, ensuring that the concrete can normally exhaust and vibrate through the steel sleeves (2); during the pouring process, a construction worker inserts a soft rubber tube into the steel sleeve (2) reserved on the guide wall (1) to pour the outer wall concrete, and the process is sequentially performed along the center direction of the outer wall, the pouring height of each layer is less than or equal to 450 mm, and the outer wall formwork is prevented from being extruded and deformed due to the too high single-time pouring height of the concrete; the vibrating rod is inserted into the sleeve to sufficiently vibrate and enhance the tightness of the joint between the outer wall and the guide wall.

3. The process for constructing basement exterior wall by top-down method after constructing horizontal bracing structure by bottom-up method according to claim 1, wherein: The outer wall structure formwork comprises a formwork body, a batten, a vertical round steel and a tension bolt, and the guide wall steel bars (10) reserved on the upper part of the guide wall (1) and the lower part of the guide wall should be deeply inserted into the inner side of the formwork.

4. The process for constructing basement exterior wall by top-down method after constructing horizontal bracing structure by bottom-up method according to claim 3, wherein: In order to prevent the guide wall steel bars (10) and the water stop steel plate (11) from being corroded due to the underground humid environment, a layer of cement paste is brushed in advance for protection.

5. The process for constructing basement exterior wall by top-down method after constructing horizontal bracing structure by bottom-up method according to claim 1, wherein: After the strength of each layer of the outer wall reaches 80Mpa, the formwork is removed, the excess screw rod is cut off, the screw rod hole is timely treated, the concrete surface is watered and maintained, the remaining basement outer wall is sequentially constructed from bottom to top, the construction flow is organized according to the above steps, the whole basement structure construction is finally completed, the side walls of the foundation pit are in a safe bracing state during the process, and sufficient working space is provided for the construction workers.

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