Steel sheet pile composite wall and reverse building method construction technology thereof

Abstract

According to the two reverse building method construction technologies of the steel sheet pile composite wall, during construction, construction of the outer side steel sheet pile wall is completed firstly, then the inner side steel concrete wall body is divided into a plurality of middle wall sections and a bottom wall section, the middle wall sections and the bottom wall section are sequentially constructed from top to bottom, and according to different forms of the steel sheet pile composite wall, the middle wall sections and the bottom wall section are sequentially constructed; and corresponding enclosing purlins or supporting beams are synchronously constructed, and the middle wall section and the bottom wall section are both connected to the steel sheet pile wall through shear force connecting pieces. The invention further discloses the steel sheet pile composite wall formed through the construction technology. According to the steel sheet pile composite wall, the steel sheet pile wall and the steel concrete wall are combined into a whole through the shearing force connecting pieces to form a permanent composite wall, the permanent composite wall has the advantages of being high in structural strength, excellent in anti-seepage performance, economical, efficient, flexible and controllable in construction period, convenient and efficient to construct and the like, the site requirement is low, and the overall construction period is shortened by 10-20% compared with a sequential construction method; the construction rhythm is controllable, and the method is particularly suitable for projects short in construction period.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit construction, specifically relating to a steel sheet pile composite wall and its reverse construction method. Background Technology

[0002] In deep foundation pit engineering, the top-down construction method is a traditional mainstream construction technique, generally employing a combined system of "pile support + cement-soil / high-pressure jet grouting cutoff wall + multiple layers of reinforced concrete / steel internal bracing". The construction process follows the principle of "layered excavation and layered support." After the foundation pit is excavated layer by layer to the designed bottom elevation, the basement floor slab is poured as a whole, followed by the sequential construction of the side walls, floors, and other main structures. During this process, replacement support structures (such as force transfer belts and temporary supports) are required to transfer lateral loads, and the original internal bracing is gradually removed, ultimately completing the basement structure construction. The most unfavorable working condition for this technique occurs when the foundation pit is excavated to the bottom, at which point the support structure experiences the most concentrated stress, and the risk of foundation pit deformation reaches its peak. Although the top-down construction method is technically mature and widely applicable, it has the following significant limitations:

[0003] (1) High cost: The cost of materials, construction and demolition of multiple internal supports accounts for 30-40% of the total cost of the foundation pit project; (2) Long construction period: The main structure construction can only be started after the entire section of the foundation pit is excavated. There is a significant waiting time for the connection of the process, and the overall construction cycle is 20-30% longer than the reverse construction method; (3) Difficult risk management: The support structure is prone to deformation during the excavation process, which may cause the surrounding strata to settle, causing displacement of adjacent buildings and underground pipelines, and causing significant interference to the surrounding environment.

[0004] A continuous steel structure support system formed by interlocking steel sheet piles serves both retaining and water-stopping functions. Construction eliminates the need for complex mud slurry wall protection, and its modular assembly significantly improves work efficiency, with the construction period per linear meter being only 1 / 3 to 1 / 2 of that of traditional pile foundations. Furthermore, steel sheet piles can be extracted and reused, with a cost per linear meter approximately 40-70% of that of pile foundations, demonstrating a significant cost advantage. However, due to the limitations of steel structure cross-sectional characteristics, the lateral stiffness of steel sheet piles is generally low, making them prone to significant horizontal deformation during excavation. This limits their application to shallow foundation pits with depths up to 7 meters, making them unsuitable for the stringent deformation control requirements of deep foundation pits.

[0005] The "two-wall integration" technology for diaphragm walls is a mainstream integrated solution for deep foundation pit projects. By merging the foundation pit support diaphragm wall with the basement exterior wall, it simultaneously achieves the triple functions of soil retention, water prevention, and load-bearing. This technology is particularly suitable for deep foundation pit projects in urban core areas where land is scarce: it not only eliminates the need for temporary support dismantling and the space occupied by the distance between the two walls, significantly improving land utilization, but also enhances overall rigidity and lateral displacement resistance through integrated structural design, optimizing the stability and impermeability of the underground structure. However, this technology also has the following limitations:

[0006] (1) It relies on large trenching equipment and has strict requirements on the flatness and bearing capacity of the construction site; (2) It is difficult to control the verticality of the wall and handle the joints of the trench sections. The joints are easy to become weak points in waterproofing and have a high risk of leakage; (3) The technology for repairing defects in the wall and structural modification in the later stage is complex and costly; (4) The overall cost is higher than that of traditional processes, the trenching cycle is long, and the mud pollution and ground disturbance generated during the construction process have a significant impact on the surrounding environment. Summary of the Invention

[0007] To at least address the aforementioned shortcomings of the prior art, this application first proposes a reverse construction method for a steel sheet pile composite wall. The steel sheet pile composite wall is annular and includes a steel sheet pile wall and a reinforced concrete wall located inside the steel sheet pile wall. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the steel sheet pile wall. The reinforced concrete wall includes several vertically arranged intermediate wall segments and a bottom wall segment. Corresponding to each intermediate wall segment, an intermediate waler is provided on the inner wall of the steel sheet pile wall. This intermediate waler is annular and extends around the inner wall of the steel sheet pile wall. The intermediate wall segments are supported on their corresponding intermediate walers. This reverse construction method includes the following steps:

[0008] (11) Drive the sheet piles to interlock and form a sheet pile wall;

[0009] (12) Excavate the soil in the foundation pit downwards until the construction elevation of the first intermediate waler is reached, and then suspend the soil excavation.

[0010] (13) Weld shear connectors on the inner wall of the sheet pile, and construct the first intermediate waler and the first intermediate wall section using the sheet pile wall as the outer template. The first intermediate wall section is supported on the first intermediate waler.

[0011] (14) Continue to excavate the soil in the foundation pit until the construction elevation of the second intermediate waler is reached, and then suspend the excavation.

[0012] (15) Weld shear connectors on the inner wall of the sheet pile, and construct the second intermediate waler and the second intermediate wall section using the sheet pile wall as the outer formwork. The second intermediate wall section is supported on the second intermediate waler.

[0013] (16) Repeat steps (14) and (15) until all intermediate walers and corresponding intermediate wall sections are completed;

[0014] (17) Continue to excavate the soil in the foundation pit until the set elevation of the bottom of the foundation pit. Weld shear connectors on the inner wall of the steel sheet piles, construct the bottom slab and bottom wall section, and connect the bottom wall section to the bottom slab.

[0015] To enhance the support strength at the top of the sheet pile wall, a top waler is preferably installed above the first intermediate wall section. The top waler can be constructed after the first intermediate wall section is completed. Before pouring the intermediate waler and intermediate wall section, the inner wall of the sheet pile wall and the interfaces between adjacent sheet piles must be cleaned and waterproofed. To improve the connection strength between the reinforced concrete wall and the sheet pile wall, U-shaped anchor bars are preferably connected to the reinforcing cage of the reinforced concrete wall. The U-shaped anchor bars can be connected to the reinforcing cage by welding or binding. To improve the waterproof performance of the sheet pile composite wall, a water-stop steel plate is preferably welded to the inner wall of the sheet piles, with the height of the water-stop steel plate within the height range of the base plate, allowing the water-stop steel plate to be poured into the base plate. To facilitate the pouring of the bottom wall section, a joint is preferably formed by extending upwards from the radially outer end of the base plate, and the joint is integrally cast with the base plate.

[0016] In this application, steel sheet pile walls are used as the support structure, and a reverse construction method is adopted, with excavation proceeding from top to bottom in layers and construction of the reinforced concrete wall proceeding simultaneously. This allows the construction of the reinforced concrete wall to be carried out in an inverted wall manner. During the construction of the reinforced concrete wall, the completed steel sheet piles are used as external formwork, and the reinforced concrete structure is poured in reverse to form the reinforced concrete wall. The steel sheet pile wall and the reinforced concrete wall together serve as the exterior wall of the basement structure, forming a steel sheet pile-reinforced concrete composite wall. This composite wall has the dual functions of temporary support (retaining soil and preventing water seepage) and permanent basement exterior wall. The steel sheet pile-reinforced concrete composite wall in this application combines the steel sheet pile wall and the reinforced concrete wall into one unit through shear connectors, forming a permanent composite wall, which has the following significant advantages:

[0017] (1) High structural strength: It fully utilizes the material advantages of steel's tensile strength and concrete's compressive strength, resulting in high overall strength and stiffness, strong resistance to lateral deformation, and can effectively control the deformation of the foundation pit, protecting the safety of adjacent buildings, structures and underground pipelines.

[0018] (2) Excellent seepage prevention performance: Steel sheet pile wall provides the first tight waterproof barrier, forming a "rigid and flexible" dual seepage prevention system with the steel concrete wall, and the waterproof effect is reliable.

[0019] (3) Two walls in one, saving and efficient: the steel sheet pile wall serves as the foundation pit support structure during the foundation pit excavation stage and as the basement exterior wall during the use stage. The steel sheet pile wall has both support and permanent external formwork functions, realizing the integration of two walls and significantly saving construction period, space and comprehensive costs.

[0020] (4) Flexible and controllable construction period: It is easy to organize the flow operation in sections, breaking the process restriction of "excavating to the bottom of the pit before constructing the structure" in the sequential construction method, realizing the simultaneous and cross-operation of basement structure construction and earthwork excavation, shortening the overall construction period by 10-20% compared with the sequential construction method, and the construction rhythm is controllable, which is especially suitable for projects with tight schedules.

[0021] (5) Convenient and efficient construction: Steel sheet pile construction equipment is small in size, has low site requirements, is convenient and quick to construct, and has high efficiency. It also does not require maintenance, which further improves the overall construction efficiency.

[0022] Furthermore, to improve construction efficiency, the intermediate wall section is poured in one go during construction, and the intermediate wall section is seamlessly connected to the adjacent upper intermediate waler.

[0023] Furthermore, to facilitate construction, in at least two adjacent intermediate wall segments, the thickness of the lower intermediate wall segment is greater than the thickness of the upper intermediate wall segment, and the thickness of the intermediate waler corresponding to the upper intermediate wall segment is less than the thickness of the lower intermediate wall segment. This design allows the reinforced concrete wall to gradually increase in thickness from top to bottom, thereby improving the compressive strength of the sheet pile composite wall. Moreover, because the upper part of the sheet pile composite wall is thinner, its strength is maintained while its cost is reduced.

[0024] Furthermore, observing vertically, in the radial direction, the inner formwork of the intermediate wall segment is located inside the upper intermediate waler, and there is a distance between the inner formwork of the intermediate wall segment and the upper intermediate waler. This distance forms the pouring port for the lower intermediate wall segment. This design eliminates the need for an external pouring port, allowing the pouring of the intermediate wall segment in the corresponding area to be completed in one go, and enabling the reinforced concrete wall to smoothly form a stepped structure that is thinner at the top and thicker at the bottom.

[0025] Furthermore, to improve construction speed, the thickness of the intermediate wall section is the same as the thickness of the corresponding intermediate waler. Installing the inner formwork once allows for the completion of the corresponding intermediate wall section and its corresponding intermediate waler in one go, reducing the frequency of inner formwork installation.

[0026] Secondly, this application also proposes a second reverse construction method for sheet pile composite walls. This sheet pile composite wall comprises two sections, spaced apart and extending parallel to each other. Along the extension direction of the sheet pile composite walls, the two sections divide the wall into at least two construction zones. In each construction zone, each sheet pile composite wall includes a sheet pile wall and a reinforced concrete wall located inside the sheet pile wall. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the sheet pile wall. The reinforced concrete wall includes several vertically arranged intermediate wall segments and a bottom wall segment. The intermediate wall segments of the two sheet pile composite walls correspond one-to-one, forming a wall segment group. For each wall segment group, an intermediate support beam group is provided. Each intermediate support beam group includes at least one intermediate support beam, which is a horizontal beam. The two ends of the intermediate support beam are respectively supported on the inner walls of the two intermediate wall segments of the corresponding wall segment group. In at least one construction zone, this reverse construction method includes the following steps:

[0027] (21) Drive the sheet piles to interlock and form a sheet pile wall;

[0028] (22) Excavate the soil in the foundation pit downwards until the construction elevation of the first intermediate support beam group is reached, and then suspend the soil excavation.

[0029] (23) Weld shear connectors on the inner wall of the sheet pile wall, and construct the first intermediate wall section of the first wall section group and the first intermediate support beam of the first intermediate support beam group using the sheet pile wall as the outer template. The two ends of the first intermediate support beam are respectively supported on the inner wall of the first intermediate wall section.

[0030] (24) Continue to excavate the soil in the foundation pit until the construction elevation of the second intermediate support beam group is reached, and then suspend the soil excavation.

[0031] (25) Weld shear connectors on the inner wall of the sheet pile wall, and construct the second intermediate wall section of the second wall section group and the second intermediate support beam of the second intermediate support beam group using the sheet pile wall as the outer formwork. The two ends of the second intermediate support beam are respectively supported on the inner wall of the second intermediate wall section.

[0032] (26) Repeat steps (24) and (25) until all wall segments and corresponding intermediate support beams are completed;

[0033] (27) Continue to excavate the soil in the foundation pit until the set elevation of the bottom of the foundation pit. Weld shear connectors on the inner wall of the steel sheet pile wall, construct the bottom plate and the bottom wall section, and connect the bottom wall section to the bottom plate.

[0034] Before pouring the intermediate support beam and intermediate wall section, the inner wall of the sheet pile wall and the interfaces between adjacent sheet piles need to be cleaned and waterproofed. To improve the connection strength between the reinforced concrete wall and the sheet pile wall, it is preferable to connect U-shaped anchor bars to the reinforcing cage of the reinforced concrete wall. The U-shaped anchor bars can be connected to the reinforcing cage by welding or binding. To improve the waterproof performance of the sheet pile composite wall, it is preferable to weld water-stop steel plates on the inner wall of the sheet piles, and the height of the water-stop steel plates should be within the height range of the bottom plate, so that the water-stop steel plates can be poured into the bottom plate. To facilitate the pouring of the bottom wall section, it is preferable to extend upward from the radial outer end of the bottom plate to form a joint, and the joint is integrally cast with the bottom plate.

[0035] In this application, steel sheet pile walls are used as the support structure, and a reverse construction method is adopted, with excavation proceeding from top to bottom in layers and construction of the reinforced concrete wall proceeding simultaneously. This allows the construction of the reinforced concrete wall to be carried out in an inverted wall manner. During the construction of the reinforced concrete wall, the completed steel sheet piles are used as external formwork, and the reinforced concrete structure is poured in reverse to form the reinforced concrete wall. The steel sheet pile wall and the reinforced concrete wall together serve as the exterior wall of the basement structure, forming a steel sheet pile-reinforced concrete composite wall. This composite wall has the dual functions of temporary support (retaining soil and preventing water seepage) and permanent basement exterior wall. The steel sheet pile-reinforced concrete composite wall in this application combines the steel sheet pile wall and the reinforced concrete wall into one unit through shear connectors, forming a permanent composite wall, which has the following significant advantages:

[0036] (1) High structural strength: It fully utilizes the material advantages of steel's tensile strength and concrete's compressive strength, resulting in high overall strength and stiffness, strong resistance to lateral deformation, and can effectively control the deformation of the foundation pit, protecting the safety of adjacent buildings, structures and underground pipelines.

[0037] (2) Excellent seepage prevention performance: Steel sheet pile wall provides the first tight waterproof barrier, forming a "rigid and flexible" dual seepage prevention system with the steel concrete wall, and the waterproof effect is reliable.

[0038] (3) Two walls in one, saving and efficient: the steel sheet pile wall serves as the foundation pit support structure during the foundation pit excavation stage and as the basement exterior wall during the use stage. The steel sheet pile wall has both support and permanent external formwork functions, realizing the integration of two walls and significantly saving construction period, space and comprehensive costs.

[0039] (4) Flexible and controllable construction period: It is easy to organize the flow operation in sections, breaking the process restriction of "excavating to the bottom of the pit before constructing the structure" in the sequential construction method, realizing the simultaneous and cross-operation of basement structure construction and earthwork excavation, shortening the overall construction period by 10%-20% compared with the sequential construction method, and the construction rhythm is controllable, which is especially suitable for projects with tight schedules.

[0040] (5) Convenient and efficient construction: Steel sheet pile construction equipment is small in size, has low site requirements, is convenient and quick to construct, and has high efficiency. It also does not require maintenance, which further improves the overall construction efficiency.

[0041] In this second type of steel sheet pile composite wall scheme, since the intermediate support beam traverses the internal space of the foundation pit, the corresponding intermediate support beam needs to be removed simultaneously when constructing the floor slab structure layer by layer from bottom to top.

[0042] Furthermore, in at least two adjacent intermediate wall sections, the thickness of the lower intermediate wall section is greater than the thickness of the upper intermediate wall section. This design allows the reinforced concrete wall to gradually increase in thickness from top to bottom, thereby improving the compressive strength of the sheet pile composite wall. Moreover, due to the reduced thickness at the top of the sheet pile composite wall, the cost can be reduced while ensuring the strength of the sheet pile composite wall.

[0043] Furthermore, observing vertically, in the two adjacent intermediate wall segments, in the width direction, the inner formwork of the lower intermediate wall segment is located inside the upper intermediate wall segment, and there is a distance between the inner formwork of the lower intermediate wall segment and the upper intermediate wall segment. This distance forms the pouring port for the lower intermediate wall segment. This design eliminates the need for an external pouring port, allowing the pouring of the corresponding area of ​​the intermediate wall segment to be completed in one go, and seamlessly connecting the intermediate wall segment with the adjacent upper intermediate wall segment. It also enables the reinforced concrete wall to smoothly form a stepped structure that is thinner at the top and thicker at the bottom.

[0044] Furthermore, the two ends of the intermediate support beams in the intermediate support beam group are respectively supported at the lower part of the intermediate wall segments of the corresponding wall segment group, and the two ends of the top support beams are respectively supported at the top of the two first intermediate wall segments of the first wall segment group. Utilizing the connecting force between adjacent intermediate wall segments, both the upper and lower ends of each intermediate wall segment can be supported by beams. The construction of the top support beams can be carried out after the construction of the first intermediate wall segment is completed.

[0045] Furthermore, this application also proposes a steel sheet pile composite wall, which is constructed using the reverse construction method described in any of the above claims. Attached Figure Description

[0046] Figure 1 This is a top view of the first embodiment of this application.

[0047] Figure 2 for Figure 1 Sectional view along the AA direction.

[0048] Figure 3 This is a view of the first embodiment after the sheet piles have been driven in.

[0049] Figure 4 This is a view of the first embodiment after the excavation of the foundation pit has reached the construction elevation of the first intermediate waler.

[0050] Figure 5 This is a view of the first embodiment after the construction of the first intermediate waler and the first intermediate wall section is completed.

[0051] Figure 6 This is a view of the first embodiment after the excavation of the foundation pit reaches the construction elevation of the second intermediate waler.

[0052] Figure 7 This is a view of the first embodiment after the construction of the second intermediate waler and the second intermediate wall section is completed.

[0053] Figure 8 This is a view of the first embodiment after the foundation pit has been excavated to the bottom and an elevation has been set.

[0054] Figure 9 This is a view of the first embodiment after construction is completed.

[0055] Figure 10 This is a top view of the second embodiment of this application.

[0056] Figure 11 for Figure 10 Sectional view along the BB direction.

[0057] Figure 12 This is a view of the second embodiment of this application after the steel sheet piles have been driven into the ground.

[0058] Figure 13 This is a view of the second embodiment after the excavation of the foundation pit has reached the construction elevation of the first intermediate support beam group.

[0059] Figure 14 This is a view of the second embodiment after the construction of the first intermediate wall segment is completed.

[0060] Figure 15 This is a view of the second embodiment after the construction of the first intermediate support beam group is completed.

[0061] Figure 16 This is a view of the second embodiment after the excavation of the foundation pit has reached the construction elevation of the second intermediate support beam group.

[0062] Figure 17 This is a view of the second embodiment after the construction of the second intermediate wall segment is completed.

[0063] Figure 18 This is a view of the second embodiment after the construction of the second intermediate support beam group is completed.

[0064] Figure 19 This is a view of the second embodiment after the elevation of the excavated pit has been set to the bottom surface.

[0065] Figure 20 This is a view of the second embodiment after construction is completed.

[0066] Figure 21This is a schematic diagram showing the construction of the floor slab structure layer by layer from bottom to top within the foundation pit, after the intermediate support beams have been removed. Detailed Implementation

[0067] The following section provides a more detailed explanation of this application in conjunction with steel sheet pile composite walls and their construction steps.

[0068] Example 1

[0069] Please see Figure 1 and Figure 2 In this embodiment, the steel sheet pile composite wall is annular, including a first steel sheet pile wall 101 on the outer side and a reinforced concrete wall on the inner side. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the first steel sheet pile wall. The first steel sheet pile wall is formed by interlocking U-shaped steel sheet piles, and the shear connectors specifically employ U-shaped anchor bars A102. Figure 2 In the diagram, 100 represents the ground.

[0070] In this embodiment, the reinforced concrete wall includes three intermediate wall segments arranged vertically and one bottom wall segment A24. For ease of description, the three intermediate wall segments are referred to as the first intermediate wall segment A21, the second intermediate wall segment A22, and the third intermediate wall segment A23 from top to bottom. Corresponding to each intermediate wall segment, an intermediate waler is provided on the inner wall of the first sheet pile wall. The intermediate waler is annular and extends around the inner wall of the first sheet pile wall. The intermediate wall segments are supported on the corresponding intermediate waler. For ease of description, the intermediate waler corresponding to the first intermediate wall segment A21 is referred to as the first intermediate waler 11, the intermediate waler corresponding to the second intermediate wall segment A22 is referred to as the second intermediate waler 12, and the intermediate waler corresponding to the third intermediate wall segment A23 is referred to as the third intermediate waler 13. In this embodiment, in order to provide more effective support for the top of the first sheet pile wall, a top waler 10 is also provided. The top waler 10 is ring-shaped and located at the top of the first intermediate wall segment A21. Figure 1 The top waler 10 was removed.

[0071] Please see Figures 3-9 The following describes the reverse construction process steps of the steel sheet pile composite wall in this embodiment:

[0072] (11) Please participate Figure 3 The U-shaped steel sheet piles are driven in, so that the U-shaped steel sheet piles interlock to form the first steel sheet pile wall 101.

[0073] (12) Please participate Figure 4Excavate the foundation pit downwards until reaching the construction elevation of the first intermediate waler 11, then suspend excavation. Next, weld U-shaped anchor bars A102 onto the inner wall of the first sheet pile wall. Clean and waterproof the inner wall of the first sheet pile wall and the interfaces of adjacent U-shaped sheet piles. Cleaning and waterproofing should be performed according to existing techniques; no special requirements are necessary. In the following steps, the cleaning and waterproofing of the inner wall of the first sheet pile wall and the interfaces of adjacent U-shaped sheet piles should be performed according to existing techniques and will not be elaborated further.

[0074] (13) Please participate Figure 5 Using the first sheet pile wall as the outer formwork, the first inner formwork A31 is erected. The first intermediate waler 11, the first intermediate wall section A21, and the top waler 10 are poured sequentially from bottom to top. The first intermediate wall section A21 is supported on the first intermediate waler 11. The thickness of the first intermediate waler 11, the first intermediate wall section A21, and the top waler 10 are all the same.

[0075] (14) Please participate Figure 6 Continue excavating the foundation pit downwards until the construction elevation of the second intermediate waler 12 is reached, at which point excavation is suspended. Then, continue welding U-shaped anchor bars A102 onto the inner wall of the first sheet pile wall, and clean and waterproof the inner wall of the first sheet pile wall and the interfaces of adjacent U-shaped sheet piles. Remove the first inner formwork A31.

[0076] (15) Please participate Figure 7 Using the first sheet pile wall as the outer formwork, a second inner formwork A32 is erected. The second intermediate waler 12 and the second intermediate wall section A22 are poured sequentially from bottom to top. The second intermediate wall section A22 is supported on the second intermediate waler 12, and its top end connects to the bottom of the first intermediate waler 11. The second intermediate waler 12 and the second intermediate wall section A22 have the same thickness.

[0077] The thickness of the second intermediate wall segment A is greater than the thickness of the first intermediate wall segment A, making the thickness of the first intermediate waler less than the thickness of the second intermediate wall segment A. Therefore, viewed vertically, in the radial direction, the second inner formwork A is located inside the first intermediate waler, and there is a distance between the second inner formwork A and the first intermediate waler, which forms the pouring gate A321 for the second intermediate wall segment A. Using the pouring gate A321, the second intermediate wall segment A is poured in one go, seamlessly connecting it to the first intermediate waler.

[0078] (16) Repeat steps (14) and (15) until all intermediate walers and corresponding intermediate wall sections are completed.

[0079] (17) Please refer to Figure 8 and Figure 9 Continue excavating the excavation pit downwards until the designated elevation of the pit bottom, A111. Continue welding U-shaped anchor bars A102 onto the inner wall of the first sheet pile wall, and clean and waterproof the inner wall of the first sheet pile wall and the interfaces of adjacent U-shaped sheet piles. Weld a water-stop steel plate A103 onto the inner wall of the first sheet pile wall, with the installation height of the water-stop steel plate A within the height range of the base plate A20. First, pour the base plate A20, extending its radial outer end upwards to form a joint A25. Then, pour the bottom wall section A24, connecting its upper and lower ends to the bottom of the third intermediate waler 13 and the top of the joint A25, respectively, thus connecting the bottom wall section A to the base plate A via the joint A25. The water-stop steel plate A is poured inside the base plate A. The joint A25 and the base plate A20 are integrally cast. The construction of the sheet pile composite wall is complete.

[0080] In this embodiment, the first steel sheet pile composite wall is circular. It can be understood that in other embodiments, the first steel sheet pile composite wall may also be elliptical, rectangular, or other deformable shapes.

[0081] Example 2

[0082] Please see Figure 10 and Figure 11 In this embodiment, the steel sheet pile composite wall includes two layers, which are spaced apart and extend in parallel. Along the extension direction of the steel sheet pile composite wall, the two steel sheet pile composite walls divide the two layers into eight construction zones. Figure 10 A portion of one of the construction areas is shown. In this application, there are no special requirements for the division of the construction area; it can be divided as needed.

[0083] In each construction zone, each sheet pile composite wall includes a second sheet pile wall 601 and a reinforced concrete wall located inside the second sheet pile wall. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the second sheet pile wall. The second sheet pile wall is formed by interlocking U-shaped sheet piles, and the shear connectors specifically use U-shaped anchor bars B602. Figure 11 In the diagram, 100 represents the ground.

[0084] The reinforced concrete wall consists of three intermediate wall segments arranged vertically and one bottom wall segment B74. The intermediate wall segments of the two steel sheet pile composite walls correspond one-to-one, and the corresponding intermediate wall segments form a wall segment group. For each wall segment group, an intermediate support beam group is set up. Each intermediate support beam group includes five intermediate support beams. The intermediate support beams are horizontal beams, and the two ends of the intermediate support beams are supported on the inner walls of the two intermediate wall segments of the corresponding wall segment group. The intermediate support beams in the same intermediate support beam group have the same elevation, and the horizontal distance between adjacent intermediate support beams in the same intermediate support beam group is 5 meters.

[0085] In this embodiment, for ease of description, the three intermediate wall segments of each sheet pile composite wall are referred to from top to bottom as the first intermediate wall segment B71, the second intermediate wall segment B72, and the third intermediate wall segment B73. Two first intermediate wall segments B71 form a first wall segment group, two second intermediate wall segments B72 form a second wall segment group, and two third intermediate wall segments B73 form a third wall segment group. The intermediate support beam corresponding to the first wall segment group is referred to as the first intermediate support beam 61, the intermediate support beam corresponding to the second wall segment group is referred to as the second intermediate support beam 62, and the intermediate support beam corresponding to the third wall segment group is referred to as the third intermediate support beam 63.

[0086] In this embodiment, in order to provide more effective support for the top of the second sheet pile wall, a top support beam 60 is also provided. The top support beam 60 is a horizontal beam, and its two ends are respectively supported on the top of the two first intermediate wall segments B71 of the first wall segment group.

[0087] Please see Figures 12-20 The following describes the reverse construction process steps for one construction area of ​​the steel sheet pile composite wall in this embodiment:

[0088] (21) Please refer to Figure 12 The U-shaped steel sheet piles are driven in, so that they interlock to form a second steel sheet pile wall 601.

[0089] (22) Please refer to Figure 13 Excavate the foundation pit downwards until reaching the construction elevation of the first intermediate support beam group, then suspend excavation. Next, weld U-shaped anchor bars B602 onto the inner wall of the second sheet pile wall, and clean and waterproof the inner wall of the second sheet pile wall and the interfaces of adjacent U-shaped sheet piles. Cleaning and waterproofing should be performed according to existing techniques; no special requirements are necessary. In the following steps, the cleaning and waterproofing of the inner wall of the second sheet pile wall and the interfaces of adjacent U-shaped sheet piles should be performed according to existing techniques and will not be elaborated further.

[0090] (23) Please refer to Figure 14 and Figure 15 Using the second sheet pile wall as the outer formwork, the first inner formwork B81 is erected, and the first intermediate wall segment B71 of the first wall segment group is poured. After the first intermediate wall segment B71 reaches the set strength, the first inner formwork B81 is removed, and the top support beam 60 and the first intermediate support beam 61 are poured. The top support beam 60 is located above the first intermediate support beam 61, and the two ends of the top support beam 60 and the first intermediate support beam 61 are respectively supported on the top and bottom of the first intermediate wall segment B71 on one side.

[0091] (24) Please see Figure 16Continue excavating the foundation pit downwards until reaching the construction elevation of the second intermediate support beam group, then suspend excavation. Next, continue welding U-shaped anchor bars B602 onto the inner wall of the second sheet pile wall, and clean and waterproof the inner wall of the second sheet pile wall and the interfaces of adjacent U-shaped sheet piles.

[0092] (25) Please see Figure 17 and Figure 18 Using the second sheet pile wall as the outer formwork, a second inner formwork B82 is erected. The second intermediate wall segment B72 of the second wall segment group is then poured. After the second intermediate wall segment B72 reaches the set strength, the second inner formwork B82 is removed, and the second intermediate support beam 62 is poured. The two ends of the second intermediate support beam 62 are respectively supported at the bottom of one side of the second intermediate wall segment B72. The thickness of the second intermediate wall segment B is greater than the thickness of the first intermediate wall segment B.

[0093] Viewed vertically, in the width direction, the second inner formwork B82 is located inside the first intermediate wall section B, and there is a distance between the second inner formwork B and the first intermediate wall section B, which forms the pouring port B821 of the second intermediate wall section B.

[0094] (26) Repeat steps (24) and (25) until all wall segments and corresponding intermediate support beams are completed.

[0095] (27) Please see Figure 10 and Figure 20 Continue excavating the excavation pit downwards until the bottom of the pit reaches the set elevation B611. Continue welding U-shaped anchor bars B602 onto the inner wall of the second sheet pile wall, and clean and waterproof the inner wall of the second sheet pile wall and the interfaces of adjacent U-shaped sheet piles. Weld a water-stop steel plate B603 onto the inner wall of the second sheet pile wall, with the installation height of the water-stop steel plate B within the height range of the base plate B70. First, pour the base plate B70, extending both sides of the base plate B upwards in the width direction to form joints B75. Then, pour the bottom wall section B74, connecting the upper and lower ends of the bottom wall section B74 to the bottom of the third intermediate support beam 63 and the top of the joints B75, respectively, so that the bottom wall section B is connected to the base plate B via the joints B75. The water-stop steel plate B is poured inside the base plate B. The joints B75 and the base plate B70 are integrally cast.

[0096] The construction of the steel sheet pile composite wall has been completed.

[0097] Please see Figure 21 The floor slab structure was constructed layer by layer from bottom to top within the foundation pit, while the corresponding intermediate support beams were simultaneously removed. Figure 21 The floor structure is not shown in the image.

Claims

1. A reverse construction method for steel sheet pile composite walls, characterized in that, The steel sheet pile composite wall is ring-shaped and includes a steel sheet pile wall and a reinforced concrete wall located inside the steel sheet pile wall. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the steel sheet pile wall. The reinforced concrete wall includes several vertically arranged intermediate wall segments and a bottom wall segment. Corresponding to each intermediate wall segment, an intermediate waler is installed on the inner wall of the steel sheet pile wall. The intermediate wall segments are supported on their corresponding intermediate walers. The reverse construction method includes the following steps: (11) Drive the sheet piles to interlock and form a sheet pile wall; (12) Excavate the soil in the foundation pit downwards until the construction elevation of the first intermediate waler is reached, and then suspend the soil excavation. (13) Weld shear connectors on the inner wall of the sheet pile, and construct the first intermediate waler and the first intermediate wall section using the sheet pile wall as the outer template. The first intermediate wall section is supported on the first intermediate waler. (14) Continue to excavate the soil in the foundation pit until the construction elevation of the second intermediate waler is reached, and then suspend the excavation. (15) Weld shear connectors on the inner wall of the sheet pile, and construct the second intermediate waler and the second intermediate wall section using the sheet pile wall as the outer formwork. The second intermediate wall section is supported on the second intermediate waler. (16) Repeat steps (14) and (15) until all intermediate walers and corresponding intermediate wall sections are completed; (17) Continue to excavate the soil in the foundation pit until the set elevation of the bottom of the foundation pit. Weld shear connectors on the inner wall of the steel sheet piles, construct the bottom slab and bottom wall section, and connect the bottom wall section to the bottom slab.

2. The reverse construction method according to claim 1, characterized in that, When constructing the intermediate wall section, the intermediate wall section is poured in one go, and the intermediate wall section is seamlessly connected to the adjacent upper intermediate waler.

3. The reverse construction method according to claim 1, characterized in that, At least in two adjacent intermediate wall segments, the thickness of the lower intermediate wall segment is greater than the thickness of the upper intermediate wall segment, and the thickness of the intermediate waler corresponding to the upper intermediate wall segment is less than the thickness of the lower intermediate wall segment.

4. The reverse construction method according to claim 1, characterized in that, Viewed vertically, in the radial direction, the inner formwork of the middle wall section is located inside the upper middle waler, and there is a distance between the inner formwork of the middle wall section and the upper middle waler, which forms the pouring port of the lower middle wall section.

5. The reverse construction method according to claim 1, characterized in that, The thickness of the intermediate wall section is the same as the thickness of the corresponding intermediate waler.

6. A reverse construction method for steel sheet pile composite walls, characterized in that, The sheet pile composite wall comprises two sections, spaced apart and extending parallel to each other, dividing the two sections into at least two construction zones along their extension direction. In each construction zone, each sheet pile composite wall includes a sheet pile wall and a reinforced concrete wall located inside the sheet pile wall. Shear connectors extending into the reinforced concrete wall are welded to the inner wall of the sheet pile wall. The reinforced concrete wall includes several vertically arranged intermediate wall segments and a bottom wall segment. The intermediate wall segments of the two sheet pile composite walls correspond one-to-one, forming a wall segment group. For each wall segment group, an intermediate support beam group is provided, with each intermediate support beam group including at least one horizontal intermediate support beam. The two ends of the intermediate support beam are respectively supported on the inner walls of the two intermediate wall segments of the corresponding wall segment group. In at least one construction zone, the reverse construction method includes the following steps: (21) Drive the sheet piles to interlock and form a sheet pile wall; (22) Excavate the soil in the foundation pit downwards until the construction elevation of the first intermediate support beam group is reached, and then suspend the soil excavation. (23) Weld shear connectors on the inner wall of the sheet pile wall, and construct the first intermediate wall section of the first wall section group and the first intermediate support beam of the first intermediate support beam group using the sheet pile wall as the outer template. The two ends of the first intermediate support beam are respectively supported on the inner wall of the first intermediate wall section. (24) Continue to excavate the soil in the foundation pit until the construction elevation of the second intermediate support beam group is reached, and then suspend the soil excavation. (25) Weld shear connectors on the inner wall of the sheet pile wall, and construct the second intermediate wall section of the second wall section group and the second intermediate support beam of the second intermediate support beam group using the sheet pile wall as the outer formwork. The two ends of the second intermediate support beam are respectively supported on the inner wall of the second intermediate wall section. (26) Repeat steps (24) and (25) until all wall segments and corresponding intermediate support beams are completed; (27) Continue to excavate the soil in the foundation pit until the set elevation of the bottom of the foundation pit. Weld shear connectors on the inner wall of the steel sheet pile wall, construct the bottom plate and the bottom wall section, and connect the bottom wall section to the bottom plate.

7. The reverse construction method according to claim 6, characterized in that, At least in two adjacent intermediate wall segments, the thickness of the lower intermediate wall segment is greater than the thickness of the upper intermediate wall segment.

8. The reverse construction method according to claim 6, characterized in that, Looking vertically, in the two adjacent intermediate wall segments, in the width direction, the inner formwork of the lower intermediate wall segment is located inside the upper intermediate wall segment, and there is a distance between the inner formwork of the lower intermediate wall segment and the upper intermediate wall segment. This distance forms the pouring port of the lower intermediate wall segment.

9. The reverse construction method according to claim 6, characterized in that, The two ends of the intermediate support beam of the intermediate support beam group are respectively supported at the lower part of the intermediate wall segment of the corresponding wall segment group, and the two ends of the top support beam are respectively supported at the top of the two first intermediate wall segments of the first wall segment group.

10. A steel sheet pile composite wall, which is constructed using the reverse construction method described in any one of claims 1-9.

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