Subway protection area large-plane deep foundation pit separate warehouse construction method

Abstract

The invention provides a metro protection area large-plane deep foundation pit separated warehouse construction method which comprises the following steps: constructing an enclosure structure, a separated warehouse structure and a steel pipe stand column pile, and dividing a foundation pit into a large warehouse far away from a metro and a small warehouse close to the metro through the separated warehouse structure; the horizontal supporting structure and the foundation pit are constructed from top to bottom in a mode of first large to second small, separate warehouse and layering; after large bin earth is excavated to the bottom of the foundation pit, small bin excavation construction is conducted, and a bottom plate structure and a support changing structure of a large bin are constructed; a bottom plate structure and a support changing structure of the small bin are constructed, and a basement structure, not affected by the horizontal supporting structure, in the large bin is constructed; a basement structure is constructed and a horizontal supporting structure is dismantled in a large and small bin synchronous bottom-to-top mode; and the steel pipe stand columns and the bin dividing structures are dismantled from top to bottom in a layered and segmented mode. According to the method, the modes of asynchronous excavation and synchronous dismantling in different bins and advanced construction of the local basement structure are adopted, deformation of the enclosure structure is reduced, the influence on the surrounding environment of the foundation pit is weakened, and the construction efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit construction, and in particular to a compartment construction method for a large-plane deep foundation pit in a subway protection zone. Background Art

[0002] With the advancement of urban underground space development and the development of subway rail transit, the construction of underground projects in existing subway operation safety protection areas and construction planning control areas is also increasing. The construction of underground projects requires excavation of foundation pits and removal of supporting structures, and these construction processes will cause deformation of the foundation pit retaining structure, which in turn affects the surrounding environment.

[0003] The traditional construction method is to excavate the foundation pit in layers as a whole, and dismantle the supporting structure layer by layer after each basement structure is completed. For foundation pits with large plane spans and deep excavation depths in the subway protection zone, conventional technical means have the following disadvantages: on the one hand, the overall excavation and unloading of the foundation pit will increase the deformation of the foundation pit retaining structure, thereby causing deformation of the soil around the foundation pit and the adjacent subway structure; on the other hand, the overall demolition construction efficiency is low and the construction time is long. Therefore, it is urgent to provide a new deep foundation pit construction method. Summary of the invention

[0004] The invention provides a compartmentalized construction method for a large-plane deep foundation pit in a subway protection zone, which solves the problems of poor foundation pit deformation control effect and low construction efficiency in the prior art.

[0005] The specific construction steps include:

[0006] S1, construction enclosure structure, compartment structure and steel pipe column piles. The compartment structure is used to divide the foundation pit into large compartments far away from the subway and small compartments close to the subway;

[0007] S2. Use the method of large warehouse first and small warehouse later, separate warehouses and layers, and carry out horizontal support structure and foundation pit excavation construction from top to bottom;

[0008] S3. After the earthwork in the large warehouse is excavated to the bottom of the foundation pit, the small warehouse horizontal support structure and foundation pit excavation are carried out, and the large warehouse bottom plate structure and replacement support structure are constructed;

[0009] S4, construct the bottom plate structure and the replacement support structure of the small warehouse, and construct the basement structure in the large warehouse that is not affected by the horizontal support structure to form a "preliminary structure area";

[0010] S5. Use large and small warehouses to construct the basement structure and dismantle the horizontal support structure from bottom to top;

[0011] S6. Finally, the steel pipe column piles and compartment structures are dismantled in layers and sections from top to bottom.

[0012] Optionally, the horizontal support structure and foundation pit excavation construction is carried out based on the method of first large and then small, compartmentalized and layered, and from top to bottom, including the following steps:

[0013] S21, first layer the warehouse foundation pit, then construct the first layer of horizontal support structure, and then excavate the first layer of earthwork;

[0014] S22. Construct the second-layer horizontal support structure, then excavate the second layer of earth, and construct each layer of horizontal support structure and earth in sequence from top to bottom until the earth is excavated to the bottom of the foundation pit.

[0015] Optionally, the basement structure is constructed and the horizontal support structure is removed in a bottom-up manner by using a large warehouse and a small warehouse synchronously, including the following steps:

[0016] S51. First, dismantle the bottom horizontal support structure of the large warehouse and the small warehouse simultaneously, and then construct the bottom basement structure and complete the support replacement;

[0017] S52, synchronously dismantle the upper horizontal support structure of the large warehouse and the small warehouse, and then synchronously construct the upper basement structure and complete the support replacement;

[0018] S53. The horizontal supporting structures are dismantled synchronously from bottom to top, and then the basement structure is constructed synchronously until the construction of the top-level basement structure is completed.

[0019] Optionally, soil reinforcement or partition walls are used on the periphery of the retaining structure on the side adjacent to the subway line to control the transmission of additional displacement by the soil.

[0020] Optionally, when constructing the bottom plate structure and the replacement support structure of the small warehouse, the "advance structure area" can be constructed all the way to the basement top plate elevation, thereby synchronizing the construction progress of the large warehouse and the small warehouse and creating conditions for the simultaneous dismantling of the horizontal support structure.

[0021] Optionally, the horizontal supporting structures at the same position on both sides of the same foundation pit compartment structure and perpendicular to the foundation pit compartment structure need to be unloaded and dismantled simultaneously to reduce uneven stress and deformation of the foundation pit support structure.

[0022] Optionally, the removal of the horizontal supporting structure and the construction of each basement structure need to be carried out simultaneously, that is, each time a basement structure is constructed, a horizontal supporting structure is removed.

[0023] Optionally, before dismantling the horizontal support structure, it is necessary to first perform support replacement construction and then perform support removal construction.

[0024] Optionally, during the removal of the horizontal support structures, the horizontal support structures not associated with the adjacent subway line foundation pit are removed first, and then the horizontal support structures associated with the adjacent subway line foundation pit are removed.

[0025] Optionally, the supporting structure may be removed after the main structure construction reaches 80% of the design strength.

[0026] The technical solution of the present invention has the following advantages:

[0027] The present invention provides a method for constructing a large-plane deep foundation pit compartment in a subway protection area. First, a retaining structure, a compartment structure and steel pipe column piles are constructed. The foundation pit is divided into a large compartment far away from the subway and a small compartment close to the subway by the compartment structure; then the horizontal support structure and the foundation pit are constructed in a way that the large compartment is first followed by the small compartment, the compartments are divided into layers, and the construction is carried out from top to bottom; after the earthwork in the large compartment is excavated to the bottom of the foundation pit, the small compartment is excavated, and the floor plate structure and the replacement support structure of the large compartment are constructed; then the floor plate structure and the replacement support structure of the small compartment are constructed, and the basement structure in the large compartment that is not affected by the horizontal support structure is constructed, that is, the advance structure area is constructed; then the basement structure is constructed synchronously with large and small compartments and from bottom to top, and the horizontal support structure is removed; finally, the steel pipe columns and the compartment structure are removed in a layered and segmented manner and from top to bottom. Through the above-mentioned construction method, the deformation of the foundation pit retaining structure can be reduced, thereby reducing the impact on the surrounding environment of the foundation pit, while shortening the construction time and improving the construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a schematic diagram of the foundation pit area division structure in step S1 of the present invention;

[0030] Figure 2 Schematic diagram of the preceding structure area of ​​step S4 of the present invention;

[0031] Figure 3 It is a schematic cross-sectional view of the foundation pit after the bottom plate structure of the small warehouse in step S3 of the present invention is completed;

[0032] Figure 4 This is a schematic diagram of the support structure that is not related to the foundation pit of the adjacent subway line before being removed in step S5 of the present invention;

[0033] Figure 5 It is a schematic diagram of the support structure unrelated to the foundation pit of the adjacent subway line after it is removed in step S5 of the present invention;

[0034] Figure 6It is a structural schematic diagram of the dismantling of the compartment structure in step S6 of the present invention.

[0035] Description of the accompanying drawings in the embodiments:

[0036] 1. Large warehouse; 2. Small warehouse; 3. Enclosure structure; 4. Sub-warehouse structure; 5. Steel pipe column piles; 6. Horizontal support structure; 7. Bottom plate structure; 8. Replacement support structure; 9. Advance structural area; 10. First angle support; 11. Second angle support; 12. First pair of supports; 13. Second pair of supports; 14. First sub-warehouse structure; 15. Second sub-warehouse structure. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Example

[0042] like Figures 1 to 6 As shown, this embodiment provides a method for constructing a large-scale subway basement compartment, including:

[0043] S1, construction enclosure structure 3, compartment structure 4 and steel pipe column piles 5. The compartment structure divides the foundation pit into a large compartment 1 far away from the subway and a small compartment 2 close to the subway;

[0044] Among them, Figure 1 As shown, when the span of the foundation pit is large, the large warehouse 1 away from the subway and the small warehouse 2 close to the subway can be provided with two or more warehouses. The present embodiment does not limit the number of the large warehouse 1 away from the subway and the small warehouse 2 close to the subway. The technical personnel in this field can change the number of the large warehouse away from the subway and the small warehouse close to the subway according to the length of the span of the foundation pit, as long as the same technical effect can be achieved.

[0045] In an embodiment of the present invention, by dividing the foundation pit into several large warehouses 1 far away from the subway and small warehouses 2 close to the subway, the foundation pit support span can be reduced, the foundation pit support stability can be improved, and the deformation control effect can be enhanced to ensure the safety of the horizontal support structure of the foundation pit.

[0046] S2, the horizontal support structure 6 and foundation pit excavation are carried out by first constructing the large warehouse 1 and then the small warehouse 2, in a divided warehouse and layered manner, from top to bottom;

[0047] Among them, Figure 3 As shown, the horizontal support structure 6 and foundation pit excavation construction are carried out by adopting the method of first large warehouse 1 and then small warehouse 2, dividing warehouses and layers, and excavating from top to bottom, including the following steps:

[0048] S21, firstly, the foundation pit of the large warehouse 1 is layered, then the first layer of horizontal support structure 6 is constructed, and then the first layer of earthwork is excavated;

[0049] S22, construct the second layer of horizontal support structure 6, then excavate the second layer of earthwork, and construct each layer of horizontal support structure 6 and earthwork from top to bottom in sequence until the earthwork is excavated to the bottom of the foundation pit, thus completing the excavation of the foundation pit of the large warehouse 1.

[0050] S3. After the earthwork in the large warehouse 1 is excavated to the bottom of the foundation pit, the horizontal support structure 6 and foundation pit excavation of the small warehouse 2 are carried out, and the bottom plate structure 7 and the replacement support structure 8 of the large warehouse 1 are constructed;

[0051] It is particularly noted that after the excavation of the earthwork in the large warehouse 1 reaches the bottom of the foundation pit, the construction of the horizontal support structure 6 and the foundation pit of the small warehouse 2 begins.

[0052] Among them, the excavation construction process of the small warehouse 2 is similar to that of the large warehouse. First, the first layer of horizontal support structure 6 is constructed, and then the first layer of earth is excavated. Then, the second layer of horizontal support structure 6 is constructed, and then the second layer of earth is excavated. The above construction process is repeated from top to bottom until the earth is excavated to the bottom of the foundation pit.

[0053] It is particularly noted that during the excavation of the earth in the small warehouse 2, the large warehouse 1 begins to construct the bottom plate structure 7 and the replacement support structure 8. When the earth in the small warehouse 2 is excavated to the bottom elevation of the second-layer horizontal support structure, the construction of the bottom plate structure 7 and the replacement support structure 8 in the large warehouse 1 is half completed. When the earth in the small warehouse 2 is excavated to the bottom of the foundation pit, the construction of the bottom plate structure 7 and the replacement support structure 8 in the large warehouse 1 is fully completed.

[0054] Specifically, in an embodiment of the present invention, when constructing the foundation pit of the large warehouse 1, the first layer of horizontal support structure 6 is constructed first, and then the first layer of earth is excavated. Then, the second layer of horizontal support structure 6 is constructed, and then the second layer of earth is excavated. This is repeated in sequence until the last layer of support structure is constructed. At this time, construction of the small warehouse 2 is started simultaneously. Similarly, the horizontal support structure 6 of the small warehouse 2 is also constructed layer by layer, and then the earth is excavated until the bottom elevation of the second layer of horizontal support structure 6 is excavated. At the same time, the bottom plate structure 7 at the bottom of the foundation pit of the large warehouse 1 is constructed. After the construction of the bottom plate structure 7 is completed, the small warehouse 2 is excavated to the bottom of the foundation pit. At the same time, the bottom plate structure 7 in the large warehouse 1 completes the support replacement operation for the bottom horizontal support structure 6.

[0055] In the embodiment of the present invention, a construction method of first large and then small, in compartments and layers, and from top to bottom is adopted, that is, the large warehouse 1 foundation pit far away from the subway is excavated in layers first to unload in advance, and when the excavation reaches the bottom of the foundation pit, the small warehouse 2 foundation pit close to the subway area is excavated in layers. When the horizontal support structure 6 in the large warehouse 1 is constructed and earthwork is excavated, the small warehouse 2 adjacent to the subway relies on the effect of the unexcavated soil in the warehouse to effectively reduce the deformation of the support structure caused by the excavation of the large warehouse and the impact on the soil around the foundation pit, thereby reducing the impact of the large warehouse excavation and unloading on the deformation of the adjacent subway structure.

[0056] S4, construct the bottom plate structure 7 and the replacement support structure 8 of the small warehouse 2, and construct the basement structure in the large warehouse 1 that is not affected by the horizontal support structure to form a "preliminary structure area";

[0057] Among them, Figure 2 As shown, the "advance structure area" is located outside the horizontal projection area of ​​the horizontal support structure 6, so it is not affected by the demolition of the horizontal support structure 6, and the "advance structure area" can be constructed all the way to the basement top plate elevation. The setting of the "advance structure area" enables the demolition of the horizontal support structure 6 and the construction of the partial basement structure in the large warehouse 1 to be carried out independently and synchronously. In other words, the "advance structure area" achieves the synchronization of the construction progress of the large warehouse 1 and the small warehouse 2, creates the conditions for the synchronous demolition of the horizontal support structure 6, and improves the construction efficiency of the basement structure while reducing the deformation of the subway structure.

[0058] S5. Use large and small warehouses to construct the basement structure and dismantle the horizontal support structure from bottom to top;

[0059] The construction of the basement structure and the removal of the horizontal support structure 6 based on the synchronous construction of the large warehouse 1 and the small warehouse 2 from bottom to top includes the following steps:

[0060] S51, first synchronously dismantle the bottom horizontal support structure 6 of the large warehouse 1 and the small warehouse 2, and then synchronously construct the bottom basement structure and complete the support replacement;

[0061] S52, synchronously dismantle the upper horizontal support structure 6 of the large warehouse 1 and the small warehouse 2, and then synchronously construct the upper basement structure and complete the support replacement;

[0062] S53, the horizontal support structure 6 is dismantled synchronously from bottom to top, and then the basement structure is constructed synchronously until the construction of the topmost basement structure is completed.

[0063] Among them, in the embodiment of the present invention, the basement structure is provided with four layers. When the bottom plate structure 7 and the replacement support structure 8 reach 80% of the design strength, the fourth layer horizontal support structure 6 in the large warehouse 1 and the small warehouse 2 is simultaneously demolished, and then the wall columns of the negative fourth layer of the basement, the beams and replacement support structure of the negative third layer of the basement in the large warehouse 1 and the small warehouse 2 are constructed; when the wall columns of the negative fourth layer of the basement and the beams and replacement support structure of the negative third layer of the basement reach 80% of the design strength, the third layer horizontal support structure in the large warehouse 1 and the small warehouse 2 is simultaneously demolished, and then the wall columns of the negative third layer of the basement, the beams and replacement support structure of the negative second layer of the basement in the large warehouse 1 and the small warehouse 2 are constructed, and the process is repeated in sequence until all horizontal support structures are demolished.

[0064] In particular, if Figure 4 and Figure 5 As shown, during the demolition process of the horizontal support structure 6, the horizontal support structure 6 not associated with the adjacent subway line foundation pit is first demolished, and then the horizontal support structure 6 associated with the adjacent subway line foundation pit is demolished. In the embodiment of the present invention, the horizontal support structure 6 not associated with the adjacent subway line foundation pit includes a first angle brace 10 and a first pair of braces 12, and the horizontal support structure 6 associated with the adjacent subway line foundation pit includes a second angle brace 11 and a second pair of braces 13. For example, taking the fourth-layer horizontal support structure as an example, the first angle brace 10 and the first pair of braces 12 not associated with the subway line foundation pit are first demolished, and then the second angle brace 11 and the second pair of braces 13 associated with the subway line foundation pit are demolished. In other words, the first angle brace 10 and the first pair of braces 12 far away from the subway line foundation pit are first demolished, and then the second angle brace 11 and the second pair of braces 13 close to the subway line foundation pit are demolished.

[0065] S6. Finally, the steel pipe column piles and compartment structures are dismantled in layers and sections from top to bottom;

[0066] Among them, Figure 6As shown, the demolition of the steel pipe column pile 5 and the compartment structure 4 does not affect each other and can be constructed in parallel. The steel pipe column pile 5 is demolished in sections according to the basement structure floor, that is, each floor is a section. The demolition of the compartment structure 4 needs to be divided into two batches. The first batch of compartment structures is set as the first compartment structure 14, and the second batch of compartment structures is set as the second compartment structure 15. The first compartment structure 14 is first demolished in intervals, and then the basement beam and slab structure of the interval area is constructed, and then the second compartment structure 15 is demolished, and then the basement beam and slab structure of the remaining area is constructed.

[0067] Furthermore, soil reinforcement or partition wall is used on the periphery of the enclosure structure 3 on the side adjacent to the subway line to control the transmission of additional displacement by the soil. In the embodiment of the present invention, a row of three-axis mixing piles is used on the periphery of the enclosure structure on the side adjacent to the subway for pre-reinforcement of the trench wall, with a spacing of 1.2 meters between each row, and the three outer rows are grouting holes, with a row spacing of 1.0 meters.

[0068] In the embodiment of the present invention, the excavation depth of the foundation pit is between 22.50m and 24.30m, the foundation pit area is about 79,500 square meters, the maximum width of the foundation pit is 322m, and the maximum length is 240m. The two horizontal and vertical compartment structures divide the foundation pit into 4 compartments, of which the horizontal compartment structure is 235m in total and the vertical compartment structure is 337m in total.

[0069] Furthermore, the horizontal support structures 6 at the same position on both sides of the same foundation pit compartment structure 4 and perpendicular to the foundation pit compartment structure 4 need to be unloaded and dismantled synchronously to reduce the uneven force deformation of the foundation pit support structure.

[0070] Furthermore, the demolition of the horizontal support structure 6 and the construction of the basement structure need to be carried out simultaneously, that is, each time a basement structure is constructed, a horizontal support structure is demolished. For example, the fourth-layer horizontal support structure is demolished, and the fourth-layer wall columns and the third-layer beams and slabs are constructed. Then the third-layer horizontal support structure is demolished, and the third-layer wall columns and the second-layer beams and slabs are constructed, and so on, until the first-layer horizontal support structure is demolished. It should be noted that after the basement structure construction reaches 80% of the design strength, the previous layer of horizontal support structure 6 is demolished.

[0071] Furthermore, during the removal of the horizontal support structure 6, it is necessary to carry out the replacement of the support and then the removal of the support. That is, the removal of each layer of the horizontal support structure 6 needs to strictly follow the principle of replacing the support first and then removing the support. During the construction of the basement structure, the replacement support system is constructed simultaneously. The horizontal support structure 6 can be removed only after the replacement support system reaches 80% of the design strength, thereby ensuring that the replacement support system replaces the concrete support to play the role of internal support.

[0072] In an embodiment of the present invention, the replacement support system includes a floor structure, a replacement support beam or replacement support plate on the outside of the foundation pit outer wall, a post-cast strip force transmission steel beam, a temporary return steel support beam for the large opening, and a replacement support structure at the location of the foundation pit compartment structure.

[0073] The present invention first constructs the enclosure structure 3, the compartment structure 4 and the steel pipe column piles 5, and divides the foundation pit into a large compartment 1 far away from the subway and a small compartment 2 close to the subway through the compartment structure 4; then the horizontal support structure 6 and the foundation pit are constructed in a top-down manner by first constructing the large compartment 1 and then the small compartment 2, and then constructing the small compartment 2 in a compartment-by-compartment and layer-by-layer manner; after the earthwork in the large compartment 1 is excavated to the bottom of the foundation pit, the small compartment 2 is excavated, and the bottom plate structure 7 and the replacement support structure 8 of the large compartment 1 are constructed; then the bottom plate structure 7 and the replacement support structure 8 of the small compartment 2 are constructed, and the bottom plate structure 7 and the replacement support structure 8 of the large compartment 1 that are not supported by the horizontal support structure are constructed. The affected basement structure is constructed, that is, the advance structure area 9 is constructed; then the large warehouse 1 and the small warehouse 2 are used to construct the basement structure synchronously and from bottom to top, and the horizontal support structure 6 is removed; then the steel pipe column piles 5 and the compartment structure 4 are removed in a layered and segmented manner and from top to bottom, and then the outer wall of the basement is constructed and the fertilizer trough is backfilled to complete the construction of the basement structure. Through the above construction method, the deformation of the foundation pit retaining structure can be avoided, thereby avoiding the impact on the surrounding environment of the foundation pit, while shortening the construction time and improving the construction efficiency.

[0074] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for constructing a large-scale deep foundation pit in a subway protection area, characterized in that: include: S1, construction enclosure structure, compartment structure and steel pipe column piles. The compartment structure is used to divide the foundation pit into large compartments far away from the subway and small compartments close to the subway; S2. Use the method of large warehouse first and small warehouse later, separate warehouses and layers, and carry out horizontal support structure and foundation pit excavation construction from top to bottom; S3. After the earthwork in the large warehouse is excavated to the bottom of the foundation pit, the small warehouse horizontal support structure and foundation pit excavation are carried out, and the large warehouse bottom plate structure and replacement support structure are constructed; S4. Construct the bottom plate structure and the replacement support structure of the small warehouse, and construct the basement structure in the large warehouse that is not affected by the horizontal support structure to form a "preliminary structure area"; S5. Use large and small warehouses to construct the basement structure and dismantle the horizontal support structure from bottom to top; S6. Finally, the steel pipe column piles and compartment structures are dismantled in layers and sections from top to bottom.

2. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: The horizontal support structure and foundation pit excavation construction is carried out in a top-down manner by adopting the method of large-scale first and small-scale later, compartment-by-compartment and layer-by-layer, including the following steps: S21, first layer the warehouse foundation pit, then construct the first layer of horizontal support structure, and then excavate the first layer of earthwork; S22. Construct the second-layer horizontal support structure, then excavate the second layer of earth, and construct each layer of horizontal support structure and earth in sequence from top to bottom until the earth is excavated to the bottom of the foundation pit.

3. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: The construction of the basement structure and the removal of the horizontal support structure are based on the use of large and small warehouses in a synchronous, bottom-up manner, including the following steps: S51. First, dismantle the bottom horizontal support structure of the large warehouse and the small warehouse simultaneously, and then construct the bottom basement structure and complete the support replacement; S52, synchronously dismantle the upper horizontal support structure of the large warehouse and the small warehouse, and then synchronously construct the upper basement structure and complete the support replacement; S53. The horizontal supporting structures are dismantled synchronously from bottom to top, and then the basement structure is constructed synchronously until the construction of the top-level basement structure is completed.

4. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: Soil reinforcement or partition walls are used on the periphery of the retaining structure adjacent to the subway line to control the transmission of additional displacement by the soil.

5. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: When constructing the bottom plate structure and the replacement support structure of the small warehouse, the "advance structure area" can be constructed all the way to the basement top plate elevation, realizing the synchronization of the construction progress of the large and small warehouses and creating conditions for the simultaneous dismantling of the horizontal support structure.

6. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: The horizontal supporting structures at the same position on both sides of the same foundation pit compartment structure and perpendicular to the foundation pit compartment structure need to be unloaded and dismantled simultaneously to reduce uneven stress and deformation of the foundation pit support structure.

7. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: The demolition of the horizontal supporting structure and the construction of each basement structure need to be carried out simultaneously, that is, each time a basement structure is constructed, a horizontal supporting structure is demolished.

8. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: Before dismantling the horizontal support structure, it is necessary to first carry out support replacement construction and then support removal construction.

9. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1 is characterized in that: During the demolition of the horizontal support structure, the horizontal support structure that is not related to the adjacent subway line foundation pit is demolished first, and then the horizontal support structure that is related to the adjacent subway line foundation pit is demolished.

10. The method for constructing a large-scale deep foundation pit in a subway protection area according to claim 1, characterized in that: After the main structure construction reaches 80% of the design strength, the supporting structure will be dismantled.

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