Internal support basement foundation pit support system and construction method thereof

Abstract

The invention provides an internal support basement foundation pit support system and a construction method thereof, and is applied to the technical field of foundation pit support, the basement foundation pit support system comprises a soil retaining structure, and a temporary horizontal support structure and a permanent vertical support structure which support the soil retaining structure along the periphery of a foundation pit, the soil retaining structure is arranged along the inner wall of a foundation pit, the permanent vertical supporting structure comprises a plurality of sets of permanent lateral force resisting vertical components at least provided with continuous stress sections with high length-width ratios in the lateral direction, the lower ends of the components are anchored below a bottom plate of a basement, and the components are constructed through a reverse construction method. After the construction is completed, retaining in a peripheral area on the inner side of the basement; a plurality of structural columns are further constructed in the peripheral area through a sequential construction method, the structural columns and the permanent lateral force resisting vertical components are distributed in the peripheral area in a staggered mode, and the foundation pit support system has the advantages that the using amount of temporary components is small, and the main body structure is convenient to use.

Description

Technical Field

[0001] This application relates to the technical field of foundation pit retaining, and particularly relates to an internal support basement foundation pit retaining system and a construction method thereof. Background Art

[0002] The existing internal support type foundation pit retaining system generally includes a soil retaining structure, an internal support structure, and an anchor component. Among them, the soil retaining structure is generally composed of retaining vertical members arranged on the side wall of the foundation pit and embedded at the lower end into the bottom surface of the foundation pit. The internal support structure is divided into horizontal members and vertical members. The horizontal members are generally horizontal braces of reinforced concrete, steel structure, or steel reinforced concrete structure, and the vertical members are generally bearing piles in the form of point piles such as column piles, cast-in-place piles, or precast piles. The anchor is a rod body extending into the soil outside the foundation pit on the soil retaining structure, such as steel strands, steel bars, or steel pipes.

[0003] The existing internal support type foundation pit retaining system generally adopts the top-down construction method, that is, excavating layer by layer downward in the natural order, and then constructing the main structure layer by layer upward. The process logic is clear, and it can avoid the complex coordination process of synchronous construction of the above-ground and underground structures in the top-down method. However, during the construction process using the top-down method, the following problems will be encountered. That is, the retaining professional generally only sets temporary lateral force resisting members inside the basement boundary line, such as internal supports, inclined braces, etc. These temporary lateral force resisting members affect the normal construction of the basement main structure and need to be demolished in advance, thus increasing the construction workload. And when these temporary lateral force resisting members are demolished, the basement has not been constructed yet, and the retaining of the foundation pit still needs to play a role, so the work of replacing the support is increased, resulting in a long retaining design period and high cost.

[0004] In some existing technologies, a method of combining top-down and bottom-up construction is also proposed for constructing the basement foundation pit retaining structure. Specifically, the basement main structure to be constructed is divided into two parts. One part is constructed using the top-down method in the peripheral area of the foundation pit. The construction structure includes a diaphragm wall, a lateral force resisting shear wall, and each floor slab. After construction, the diaphragm wall, the lateral force resisting shear wall, and the floor slab jointly serve as the soil retaining and water blocking structure. The other part is constructed using the bottom-up method in the remaining area of the foundation pit. After construction, the two parts of the main structure are correspondingly connected through their respective floor slabs. Although adopting this idea can reduce the workload of demolishing some temporary components and replacing the support, the following potential problems will exist: First, since part of the construction of the basement main structure adopts the top-down method and part adopts the bottom-up method, the processes are complex and changeable, and the treatment of the connection structure between the top-down and bottom-up methods is difficult, and the construction quality is difficult to guarantee.

[0005] Second, during the construction of the top-down method, permanent structures such as diaphragm walls and lateral shear walls are rigidly connected to the floor slabs and bear loads during the construction stage, and their spatial layout and mechanical properties cannot meet the requirements of later building use. For example, during later use, they need to bear large vertical loads, but the distance between the lateral shear walls is large, resulting in a very high beam height and affecting the use function of the building. Summary of the Invention

[0006] In view of this, the embodiments of this specification provide an internal support basement foundation pit retaining system and its construction method, which have the advantages of less use of temporary components, convenient use of the main structure, comfort, etc.

[0007] The embodiments of this specification first provide an internal support basement foundation pit retaining system, including a soil retaining structure, a temporary horizontal support structure and a permanent vertical support structure that laterally support the soil retaining structure. The soil retaining structure is arranged along the inner wall of the foundation pit. The permanent vertical support structure includes multiple groups of permanent lateral force resisting vertical members with a continuous stress cross-section having a high aspect ratio at least laterally. The lower end of the member is anchored below the basement floor slab, and the member is constructed by the top-down method and remains in the peripheral area on the inner side of the basement after construction. In this peripheral area, multiple structural columns are also constructed by the bottom-up method, and the multiple structural columns and the multiple groups of permanent lateral force resisting vertical members are staggered in this peripheral area.

[0008] To optimize the above solution, the following technical measures are also taken: As one of the implementation manners, the permanent lateral force resisting vertical member adopts a reinforced concrete structure, a steel structure, or a combined structure of reinforced concrete and steel structure.

[0009] As one of the implementation manners, the permanent lateral force resisting vertical member is composed of multiple pile foundations arranged side by side laterally; and / or the permanent lateral force resisting vertical member is formed by pouring concrete for multiple vertical bearing piles arranged laterally; and / or the permanent lateral force resisting vertical member is formed by steel structure restraint for multiple vertical bearing piles arranged laterally.

[0010] As one of the implementation manners, the permanent lateral force resisting vertical member is arranged in the form of a single-wall.

[0011] As one of the implementation manners, the permanent lateral force resisting vertical member improves the stiffness of the member by taking prestress measures.

[0012] As one of the implementation manners, the permanent lateral force resisting vertical member improves the lateral force resistance ability by taking ballast measures.

[0013] As one of the embodiments, the retaining structure includes a plurality of vertical retaining members, and the temporary horizontal support structure includes a plurality of temporary lateral force resisting horizontal members, and the vertical retaining members and / or the temporary lateral force resisting horizontal members are detachable and reusable members.

[0014] As one of the embodiments, the temporary horizontal support structure further includes a support plate, the support plate is connected to the temporary lateral force resisting horizontal member, and the surface of the support plate is adapted to provide a construction operation site.

[0015] As one of the embodiments, after the construction of the basement is completed, the permanent vertical lateral force resisting member is located inside the outer wall of the basement and is arranged perpendicular to the wall surface of the outer wall of the basement.

[0016] 10. A construction method of an internal support basement foundation pit retaining system as described above, specifically including the following steps: S1. Construct the retaining structure and the permanent vertical lateral force resisting member in the foundation pit according to the design drawings, and construct the pile foundation of the main structure as needed; S2. Excavate the internal soil of the foundation pit between the ground and the first temporary horizontal support structure; S3. Construct the first temporary horizontal support structure and complete the connection of the first temporary horizontal support structure with the retaining structure and the permanent vertical lateral force resisting member; S4. After the strength of the first temporary horizontal support structure reaches the requirement, excavate the internal soil of the foundation pit between the first temporary horizontal support structure and the second temporary horizontal support structure; S5. Construct the second temporary horizontal support structure and complete the connection of the second temporary horizontal support structure with the retaining structure and the permanent vertical lateral force resisting member; S6. Repeat steps S4 to S5 until after the construction of the last temporary horizontal support structure is completed, excavate the internal soil of the foundation pit between the last temporary horizontal support structure and the foundation bottom until the earthwork excavation is completed; S7. Construct the basement floor slab and complete the connection of the floor slab with the retaining structure and the permanent vertical lateral force resisting member; S8. Remove the temporary support structure in sequence and construct the basement main structure including a plurality of structural columns at the same time.

[0017] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification at least include: Firstly, in the present invention, in order to meet the performance requirements of foundation pit support, the permanent vertical lateral force resisting member is set to have a continuous stress cross-section with a high aspect ratio laterally. In this way, the lateral stiffness of the member is greatly increased, thereby enhancing the overall support capacity or the earth retaining and water retaining capacity of the foundation pit retaining system. The cross-sectional moment of inertia formula is 1 / 12bh 3, for a conventional foundation pit, assuming a 1m-thick diaphragm wall with a length of 18m, its moment of inertia is 1 / 12 x 18 x 1 3 = 1.5m 4 ; while adopting the technology of the present invention, assuming the permanent lateral force resisting vertical member is 0.8m thick and 5m long, its moment of inertia is 1 / 12 x 0.8 x 5 3 = 8.33m 4 , that is, the flexural capacity of this member can reach 5.6 times that of a conventional foundation pit.

[0018] Furthermore, in the present invention, the permanent lateral force resisting vertical member is constructed by the top-down method and is retained in the peripheral area on the inner side of the basement after construction. The other main basement structures are still constructed by the bottom-up method. This makes the foundation pit retaining system have good post-construction performance. After the earth excavation is completed, multiple structural columns can be constructed in the above-mentioned peripheral area according to needs by the bottom-up method. These structural columns and multiple groups of permanent lateral force resisting vertical members are arranged staggeredly in this peripheral area, which can reduce the distance between adjacent vertical members in this area, thereby reducing the span of the beam and the height of the beam.

[0019] In addition, retaining the lateral force resisting vertical member as a permanent member in the peripheral area on the inner side of the basement can also be coordinated with some flexibly planned spaces such as parking space, with almost no impact on the building function, and can maximize the use efficiency of the basement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 is the construction plan schematic diagram in the first embodiment of the present application; Figure 2 is the cross-sectional schematic diagram in the first embodiment of the present application; Figure 3 is the basement building plan layout schematic diagram in the first embodiment of the present application; Figure 4 is the existing basement building plan layout schematic diagram; Figure 5 is the basement structure plan layout schematic diagram in the first embodiment of the present application; Figure 6 is the cross-sectional schematic diagram when taking the weight pressing measure in the first embodiment of the present application; Figure 7It is a schematic cross-sectional view when prestress measures are taken in the first embodiment of the present application; Figure 8 It is a schematic structural view of one form of the permanent lateral force resisting vertical member in the first embodiment; Figure 9 It is a schematic structural view of another form of the permanent lateral force resisting vertical member in the first embodiment. Detailed implementation manners

[0022] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0023] The following uses specific specific examples to illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0024] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0025] It also needs to be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The drawings only show the components related to the present application and are not drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in its actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0026] The embodiments of this specification propose an internal support basement foundation pit retaining system and its construction method, as Figure 1As shown, it aims to solve the problems in the prior art that the internal support type foundation pit retaining system has a large amount of temporary support members used during construction, resulting in a large amount of work for demolition or replacement support, or the main structure construction process is complex and variable. It can further reduce the usage amount of temporary support members during construction on the basis of still adopting the traditional top-down construction method.

[0027] The following will describe the technical solutions provided by each embodiment of the present application with reference to the accompanying drawings.

[0028] Embodiment 1

[0029] As Figures 1 to 3 and Figure 5 shown, the embodiment of this specification first provides an internal support basement foundation pit retaining system, where the basement includes at least one basement floor. In this embodiment, a two-story basement is taken as an example to illustrate this solution. However, it should be understood that this is not a limitation on the protection scope of the present invention. In fact, the foundation pit retaining system in the present invention is particularly suitable for the construction of multi-story basements, such as three-story or more basements.

[0030] Specifically, the internal support basement foundation pit retaining system includes a soil retaining structure 1 and an internal support structure that supports the soil retaining structure 1 along the perimeter of the foundation pit. The soil retaining structure 1 is arranged along the inner wall of the foundation pit. The internal support structure includes a temporary horizontal support structure and a permanent vertical support structure. The permanent vertical support structure includes multiple groups of permanent lateral force resisting vertical members 24 with a high aspect ratio continuous stress section at least laterally. The lower end of the member is anchored below the basement floor slab 43. The member is constructed by the top-down method and serves as a lateral force resisting member of the foundation pit during basement construction. After construction is completed, it is retained in the peripheral area inside the basement and serves as a part of the vertical load-bearing member of the basement. In this peripheral area, multiple structural columns 5 are also constructed by the top-down method. The multiple structural columns 5 and the multiple groups of permanent lateral force resisting vertical members are arranged in a staggered manner in this peripheral area.

[0031] Here, except for the lateral force resisting vertical members 24, the main structure of the basement still adopts the traditional top-down construction method, that is, excavation first and then construction. During the construction process, the lateral force resisting vertical members 24 do not bear the vertical force of the above-ground tower structure. To meet the requirements of foundation pit support, the present invention sets the lateral force resisting vertical members 24 to have a continuous stress section with a high aspect ratio laterally. In this way, the lateral stiffness of the member is greatly increased, thereby enhancing the overall support capacity or the soil retaining and water blocking capacity of the foundation pit retaining system. On this basis, as Figure 3As shown, the lateral force resisting vertical member 24 is retained as a permanent member in the peripheral area of the basement. Preferably, it is retained in the peripheral area of the basement that avoids the above-ground tower structure. The lateral force resisting vertical member 24 is retained in this area and coordinated with some flexibly planned spaces such as parking space, with almost no impact on the building function, and can maximize the utilization efficiency of the basement. In this way, both the usage amount of temporary support members is reduced, and a reasonable and efficient arrangement and layout of the permanent-temporary combined members used in the top-down construction method in the basement main structure are achieved.

[0032] As Figure 3 and Figure 5 shown, here, the permanent lateral force resisting vertical member is constructed by the top-down method and retained in the peripheral area inside the basement after construction. The other basement main structures are still constructed by the bottom-up method, which makes the foundation pit retaining system have good post-usage performance. After the earth excavation is completed, multiple structural columns 5 can be constructed in the above-mentioned peripheral area according to needs by the bottom-up method. These structural columns 5 and multiple groups of permanent lateral force resisting vertical members 24 are arranged staggeredly in this peripheral area, which can reduce the distance between adjacent vertical members in this area, thereby reducing the height of the beam 6 in the basement main structure. In addition, in the prior art, in the peripheral area of the basement, because the top-down method is to be used for construction, all vertical members must be completed by pile driving, with great construction difficulty and low positioning accuracy. Therefore, as Figure 3 shown, in this embodiment, the structural columns 5 are constructed by the normal bottom-up method, with small construction difficulty and accurate positioning.

[0033] Here, the "lateral direction" especially refers to the direction along which the lateral force is transmitted. The "continuous stress section" means that the member has continuous stress performance without mutation at least in a certain direction, and this certain direction especially refers to the lateral direction, and can also refer to the direction of the pressure of the surrounding soil. The "length" of the aspect ratio refers to the length of the vertical member extending in the lateral direction, and the "width" of the aspect ratio refers to the length of the vertical member extending in the horizontal direction perpendicular to the lateral direction, that is, the thickness. A high aspect ratio, for example, means that the aspect ratio is at least greater than 1:1. In some ways, it can also be defined as greater than 2:1 or 3:1. Compared with the point-column-shaped vertical member, the lateral force resisting vertical member 24 in this embodiment can obtain a higher lateral stiffness due to the above-mentioned special cross-sectional structure, and thus can significantly improve the support capacity of the foundation pit. For example, the cross-sectional moment of inertia formula is 1 / 12bh 3 , for a conventional foundation pit, assuming a diaphragm wall with a thickness of 1m and a length of 18m, its moment of inertia is 1 / 12 x 18 x 1 3 = 1.5m 4 ; while using the technology of the present invention, assuming that the permanent lateral force resisting vertical member has a thickness of 0.8m and a length of 5m, its moment of inertia is 1 / 12 x 0.8 x 53 = 8.33 m 4 , that is, the flexural capacity of the component can reach 5.6 times that of a conventional foundation pit.

[0034] It should be noted that since the vertical lateral force resisting member 24 is not removed after the basement is completed and also serves as the vertical load-bearing member of the main structure, it needs to meet the requirements of the stress state of the foundation pit as well as the stress state of normal use. This vertical member belongs to a member that combines permanent and temporary functions, and its position and cross-section also need to meet the requirements of multiple disciplines such as architecture, structure, and foundation pit.

[0035] In this embodiment, the structural form of the vertical lateral force resisting member is rich, and it can be a reinforced concrete structure, a steel structure, or a combined structure of reinforced concrete and steel structure. Similarly, the temporary horizontal support structure adopts a reinforced concrete structure, a steel structure, or a combined structure of reinforced concrete and steel structure.

[0036] In some special embodiments, as Figure 8 shown, the vertical lateral force resisting member 24 can be composed of multiple pile foundations 241 arranged side by side laterally or composed of multiple vertical bearing piles arranged laterally and constrained by a steel structure, where the bearing piles are, for example, precast piles or cast-in-place piles, etc. And the construction methods are flexible and diverse, and can be precast, cast-in-place, or a combination of precast and cast-in-place, etc.

[0037] Preferably, a plurality of the vertical lateral force resisting members 24 are arranged around the peripheral area of the foundation pit, and they can have different aspect ratios in the horizontal direction, as Figure 1 shown. Since the vertical lateral force resisting member 24 has a higher lateral stiffness compared to the point-column vertical member, only a smaller number of the above-mentioned vertical lateral force resisting members 24 are needed to replace a large number of point-column vertical members for temporary support to meet the support requirements of the foundation pit. The cancellation of a large number of point-column vertical members and the horizontal support members connected thereto can save a large amount of internal space of the foundation pit and bring great convenience to the construction operation.

[0038] Preferably, as Figure 7 shown, the vertical lateral force resisting member 24 increases the member stiffness by taking prestressing measures. In some ways, a plurality of prestressed ducts are embedded inside the vertical lateral force resisting member 24, and the steel strands 7 are inserted by the post-tensioning method and tensioned to the design stress, and then grouted with cement slurry for sealing after being fixed by the anchor to form a prestressed system to increase the member stiffness and reduce the deformation generated under load.

[0039] Preferably, as Figure 6As shown, the lateral force resisting vertical member 24 enhances its lateral force resistance capacity by taking ballast measures, such as adding ballast weights at the top of the vertical member. As a reasonable application aspect, the temporary horizontal support structure further includes a support plate (not shown in the figure), and the support plate is connected to the lateral force resisting horizontal member 23. For example, as Figure 1 shown, the support plate can be fixed on the prefabricated steel truss, and the surface of the support plate is suitable for providing a construction operation site. In this way, it not only facilitates the on-site construction operation, but also the weight borne by the support plate acts on the lateral force resisting vertical member 24, achieving the effect of ballast, further increasing the lateral stiffness of the permanent lateral force resisting vertical member 24, and thus improving the safety of the foundation pit support. As other reasonable application aspects, ballast can also be provided, such as applying any available heavy objects on-site to the lateral force resisting vertical member 24, which is not limited herein. Further, the support plate is a detachable and reusable member.

[0040] In some embodiments, the vertical support structure may further include some steel columns, steel section composite columns, etc. for temporary auxiliary support.

[0041] In this embodiment, the retaining structure 1 includes retaining vertical members, which mainly bear the pressure of the soil mass outside the foundation pit and play the role of retaining soil and water. The horizontal support structure includes lateral force resisting horizontal members 23. The retaining vertical members and / or the lateral force resisting horizontal members are detachable and reusable members, thus saving construction costs. Compared with the prior art where the horizontal support members serve both as temporary retaining members and as permanent structural floor slabs, it can avoid the inconvenience caused by considering the stress conditions in two working states. For example, due to insufficient support stiffness, long-term deformation exceeds the limit after becoming a floor slab, resulting in wall cracking.

[0042] Specifically, a displacement compensation device can also be provided on the lateral force resisting horizontal member to compensate for the displacement of the lateral force resisting horizontal member under the action of temperature and load, which has an impact on the safety of the foundation pit.

[0043] Specifically, the retaining vertical members can adopt sheet pile retaining piles or steel section composite piles, steel sheet piles, etc. Further, the retaining structure 1 further includes a capping beam and / or a waist beam provided on the retaining vertical members to realize the connection between the retaining vertical members and the horizontal support structure. Compared with using non-removable members such as diaphragm walls, the construction process of the retaining vertical members here is simple and the cost is low. Preferably, the lateral force resisting horizontal member 23 can adopt a steel structure, such as a steel pipe support structure, a steel section support structure or Figure 1 the prefabricated steel truss support structure shown, etc.

[0044] Preferably, as Figure 9As shown, the vertical lateral force resisting member 24 is arranged in the shape of a straight wall 242. After the construction of the basement is completed, the vertical lateral force resisting member 24 is located inside the exterior wall 41 of the basement and is arranged perpendicular to the wall surface of the exterior wall 41 of the basement. As a preferred solution, rows of parking spaces are arranged along the inner side of the exterior wall 41 of the basement, and the vertical lateral force resisting members 24 are spaced apart and distributed in the areas separated by at least some of the parking spaces and the adjacent parking spaces, and the long sides of the vertical lateral force resisting members 24 in the horizontal direction are parallel to the extending directions of the parking spaces on both sides, as follows Figure 3 As shown, the permanently arranged vertical lateral force resisting members 24 arranged in this way only occupy some empty spaces in the original area around the basement, have little impact on the building functions, and can maximize the utilization efficiency of the basement.

[0045] Embodiment 2

[0046] On the basis of Embodiment 1, this embodiment further proposes a construction method based on the above-mentioned foundation pit retaining system, as Figure 2 shown, wherein the temporary horizontal support structure at least includes a first horizontal support structure 21 and a second horizontal support structure 22, and this construction method specifically includes the following steps: S1. Construct the retaining structure 1 of the foundation pit and the permanent vertical lateral force resisting members 24 according to the design drawings, and simultaneously construct the pile foundation of the main structure as required; S2. Excavate the soil inside the foundation pit between the ground and the first horizontal support structure 21; S3. Construct the first horizontal support structure 21 and complete the connection of the first horizontal support structure 21 with the retaining structure 1 and the permanent vertical lateral force resisting members 24; S4. After the strength of the first horizontal support structure 21 reaches the requirements, excavate the soil inside the foundation pit between the first horizontal support 21 structure and the second horizontal support structure 22; S5. Construct the second horizontal support structure 22 and complete the connection of the second horizontal support structure 22 with the retaining structure 1 and the permanent vertical lateral force resisting members 24; S6. Repeat steps S4 to S5 until after the construction of the last horizontal support structure is completed, excavate the soil inside the foundation pit between the last horizontal support structure and the foundation bottom until the earthwork excavation is completed; Preferably, a support plate that can be used as a construction operation site is provided in the first horizontal support structure 21 and / or the second horizontal support structure 22, which is not only convenient for construction but also can apply a dead weight to the permanent vertical lateral force resisting members 24 to increase the lateral bearing capacity of the vertical members, thereby enhancing the safety of the foundation pit retaining; S7. Construct the basement floor slab 43 and complete the anchoring connection of the floor slab 43 with the retaining structure 1 and the permanent vertical lateral force resisting members 24; S8. Demolish the temporary support structure successively, and simultaneously construct multiple structural columns 5, the internal floor slabs 42 of the basement and the exterior basement wall 41, and then construct the basement top slab; S9. Backfill the gap between the foundation pit retaining structure 1 and the exterior basement wall 41.

[0047] In summary, in the above embodiments, most of the main structure of the basement still adopts the traditional top-down construction method, with mature construction procedures and low cost. In order to meet the performance requirements of the foundation pit support, the lateral force-resistant vertical member 24 is set to have a continuous stress section with a high aspect ratio laterally. In this way, the lateral stiffness of the member is greatly increased, thereby enhancing the overall support capacity of the foundation pit retaining system. On this basis, the foundation pit retaining system has good flexibility for later transformation. After the earth excavation is completed, multiple structural columns 5 can be constructed in the above-mentioned peripheral area according to needs by the top-down construction method. These structural columns 5 and multiple groups of permanent lateral force-resistant vertical members 24 are arranged staggeredly in this peripheral area, which can reduce the span between adjacent vertical members in this area, thereby reducing the height of the beam 6.

[0048] In this specification, for the same or similar parts among the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and reference can be made to the partial description of the foregoing embodiments for the relevant parts.

[0049] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An internal support basement foundation pit enclosure system, comprising a retaining structure and a temporary horizontal support structure and a permanent vertical support structure supporting the retaining structure along the periphery of the foundation pit, wherein the retaining structure is arranged along the inner wall of the foundation pit, and is characterized in that: The permanent vertical support structure includes multiple groups of permanent lateral force resisting vertical components with high aspect ratio continuous load-bearing sections at least in the lateral direction, wherein the lower ends of the components are anchored under the bottom slab of the basement, and the components are constructed using a reverse construction method. During the construction of the basement, they serve as lateral force resisting components of the foundation pit, and after the construction is completed, they are retained in the surrounding area inside the basement as part of the vertical load-bearing components of the basement. In the surrounding area, multiple structural columns are also constructed using a forward construction method, and the multiple structural columns and the multiple groups of permanent lateral force resisting vertical components are arranged in a staggered manner in the surrounding area.

2. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The permanent lateral force resisting vertical member adopts reinforced concrete structure or steel structure or a combination of reinforced concrete and steel structure; the temporary horizontal supporting structure adopts reinforced concrete structure or steel structure or a combination of reinforced concrete and steel structure.

3. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The permanent lateral force resisting vertical member is composed of a plurality of pile foundations arranged in a line laterally; and / or the permanent lateral force resisting vertical member is composed of a plurality of vertical bearing piles arranged laterally and constrained by a steel structure.

4. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The permanent lateral force resisting vertical components are arranged in the form of a straight shear wall, and the shear wall is a cast-in-place component or a factory prefabricated component.

5. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The permanent lateral force resisting vertical component improves the component stiffness by taking prestressing measures; the temporary horizontal supporting structure coordinates the deformation of the side of the foundation pit by taking prestressing measures.

6. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The permanent lateral force resisting vertical component improves its lateral force resisting capacity by taking weight-bearing measures.

7. The internal support basement foundation pit containment system according to claim 1 is characterized in that: The retaining structure includes a plurality of retaining vertical members, and the temporary horizontal support structure includes a plurality of temporary lateral force resisting horizontal members. The retaining vertical members and / or temporary lateral force resisting horizontal members are removable and reusable members.

8. The internal support basement foundation pit containment system according to claim 7 is characterized in that: The temporary horizontal support structure also includes a support plate, which is connected to a temporary lateral force resisting horizontal member, and the surface of the support plate is suitable for providing a construction site.

9. The internal support basement foundation pit containment system according to claim 1, characterized in that: After the basement construction is completed, the permanent lateral force resisting vertical member is located on the inner side of the basement outer wall and is arranged perpendicular to the wall surface of the basement outer wall.

10. A construction method for an internally supported basement foundation pit retaining system according to any one of claims 1 to 9, characterized in that: The steps include: S1. Construct the retaining structure and permanent lateral force-resisting vertical components of the foundation pit according to the design drawings, and construct the pile foundation of the main structure as needed; S2, dig the soil inside the foundation pit from the ground to the first temporary horizontal support structure; S3, construct the first temporary horizontal support structure, and complete the connection between the first temporary horizontal support structure and the retaining structure and the permanent lateral force resisting vertical member; S4. After the strength of the first temporary horizontal support structure reaches the requirement, excavate the soil inside the foundation pit between the first temporary horizontal support structure and the second temporary horizontal support structure; S5. Construct a second temporary horizontal support structure and complete the connection between the second temporary horizontal support structure and the retaining structure and the permanent lateral force resisting vertical member; S6, repeating steps S4 to S5 until the last temporary horizontal support structure is completed, and digging the soil inside the foundation pit from the last temporary horizontal support structure to the base until the earthwork excavation is completed; S7. Construct the basement floor slab and complete the connection between the floor slab and the retaining structure and permanent lateral force resisting vertical components; S8. Remove the temporary supporting structures one by one and construct the main structure of the basement including multiple structural columns at the same time.

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