Modular foundation pit excavation construction method based on standard steel support structure

Abstract

The application provides a kind of modular foundation pit excavation construction method based on standard steel support structure, belongs to foundation pit technical field, comprising: S1: according to construction organization progress plan, according to foundation pit construction range and construction partition area, several partition straight lines are set along the transverse direction of foundation pit, several partition straight lines are set along the longitudinal direction of foundation pit, and the entire foundation pit construction range is divided into several construction partitions by partition straight line;S2: the intersection of partition straight line along the transverse direction of foundation pit and partition straight line along the longitudinal direction of foundation pit is the construction position of rigid platform unit;S3: select at least one construction partition to carry out simultaneous construction;S4: construction partition starts construction;S5: repeat steps S3-S4 until construction is completed;S6: after construction is completed, remove rigid platform unit and standard steel component unit and recycle.The method significantly improves construction efficiency, shortens the total construction period, makes the project progress, quality and safety risk highly controllable, and solves the safety and efficiency bottleneck during partition conversion.

Description

Technical Field

[0001] This invention relates to the field of foundation pit technology, and more specifically to a modular foundation pit excavation construction method based on a standard steel support structure. Background Technology

[0002] In the practice of ultra-large and ultra-deep foundation pit engineering, traditional construction methods are facing increasingly severe systemic challenges in terms of structural systems, construction organization, resource utilization, and process control. Traditional support systems, mainly based on cast-in-place concrete supports or steel supports, lack rigid connections between support members, have weak nodes, poor overall integrity, cannot effectively redistribute loads, and have weak deformation control capabilities. During construction, support construction conflicts with earthwork excavation and structural construction procedures, the space under the supports cannot be effectively utilized, and work platforms need to be erected separately, creating a dilemma of "support first, then no working surface" or "working surface first, then no effective support," resulting in low space utilization, significant safety hazards, and lengthy construction periods. For ultra-large foundation pits implementing zoning and block-based, flow-line operations, it is impossible to flexibly adapt to the needs of zoning and block-based, flow-line operations in ultra-large foundation pits. Zoning transitions often require complex partial dismantling and reinstallation processes, which not only cause delays and increased costs but also leave construction in a dangerous transition period with an incomplete support system for a long time. Furthermore, the installation, dismantling, and pit bottom operations are constantly exposed to complex and dangerous environments involving high altitudes, edges, and overlapping work, significantly increasing safety risks such as falls from heights and being struck by objects, resulting in immense pressure on safety protection. Meanwhile, concrete supports are one-time temporary structures, generating a large amount of construction waste upon dismantling; while traditional steel supports are theoretically recyclable, their low standardization, complex joint construction, and susceptibility to damage and deformation during dismantling lead to low actual reuse rates and recycling rates, resulting in high life-cycle costs, falling far short of the requirements of green building and a circular economy.

[0003] In summary, existing foundation pit construction technologies have significant shortcomings in terms of overall structural stability, dynamic process adaptability, and efficient resource utilization. Therefore, there is an urgent need for a systematic, modular, and dynamically adjustable foundation pit excavation construction method that deeply integrates advanced support structures with efficient construction organization on a rigid platform basis. This would further optimize the entire process from platform layout and construction organization to resource recycling, enabling safe, efficient, green, and intelligent construction of ultra-large foundation pits. Summary of the Invention

[0004] The purpose of this invention is to provide a modular foundation pit excavation construction method based on a standard steel support structure to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a modular foundation pit excavation construction method based on a standard steel support structure, comprising the following steps: S1: According to the construction organization schedule, based on the construction scope and construction zone area of ​​the foundation pit, several zoning lines are set along the horizontal direction of the foundation pit and several zoning lines are set along the vertical direction of the foundation pit. The zoning lines divide the entire foundation pit construction scope into several construction zones. S2: The intersection of the zoning lines along the transverse direction of the foundation pit and the zoning lines along the longitudinal direction of the foundation pit is the construction location of the rigid platform unit. S3: Based on the construction organization schedule, select at least one target construction zone for simultaneous construction; S4: Construction begins in the target construction zone; S5: Repeat steps S3-S4 until the entire foundation pit construction area is completed; S6: After construction is completed, the rigid platform unit and standard steel component unit shall be dismantled and recycled.

[0007] Furthermore, in step S1, the spacing between adjacent zoning lines along the transverse direction of the foundation pit first satisfies:

[0008] in, This indicates the spacing between adjacent straight lines along the transverse direction of the foundation pit; This indicates the number of standard steel components, and is an integer. This indicates the modular length of a single section of a standard steel structural member. Secondly, the spacing between adjacent zoning sections along the transverse direction of the foundation pit must also meet the following requirements:

[0009] in, This represents the maximum spacing between adjacent zonal lines along the transverse side of the foundation pit, calculated from the critical buckling pressure of the rigid platform unit after stability verification. This indicates the modulus of elasticity of a standard steel structural member. Represents the moment of inertia of a standard steel structural member section; This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components.

[0010] Furthermore, in step S1, the spacing between adjacent partition lines along the longitudinal direction of the foundation pit first satisfies:

[0011] in, This indicates the spacing between adjacent straight lines along the longitudinal direction of the foundation pit; This indicates the number of standard steel components, and is an integer. This indicates the modular length of a single section of a standard steel structural member. Secondly, the spacing between adjacent zones along the longitudinal direction of the foundation pit must also meet the following requirements:

[0012] in, This represents the maximum spacing between adjacent longitudinal partition lines along the foundation pit, calculated from the critical buckling pressure of the rigid platform unit after stability verification. This indicates the modulus of elasticity of a standard steel structural member. Represents the moment of inertia of a standard steel structural member section; This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components.

[0013] Furthermore, in step S1, the span of the construction zone along the transverse and longitudinal directions of the foundation pit satisfies:

[0014] in, This indicates the span of the construction zone along the transverse or longitudinal direction of the foundation pit; Indicates the effective operating radius; Effective operating radius The formula is:

[0015] in, Indicates the design depth of the foundation pit The critical operating radius below; This indicates the safe clearance between the standard steel components and the bucket wall to prevent collisions.

[0016] Furthermore, in step S2, the rigid platform unit includes multiple rows of vertical columns and horizontal supports. The vertical columns are arranged along the transverse and longitudinal directions of the foundation pit, respectively. The horizontal supports are at least one layer deep and include orthogonal steel braces and diagonal steel braces. The orthogonal steel braces are orthogonally connected to adjacent vertical columns, and the diagonal steel braces are located at the corners and diagonally connected to the adjacent vertical columns at the corners. The top layer of horizontal supports is fixedly installed at the top of the vertical columns, and prefabricated steel trestle plates are laid on the top layer of horizontal supports. The prefabricated steel trestle plates are connected to the upper flanges of the orthogonal steel braces and diagonal steel braces.

[0017] Furthermore, the vertical column is a standard steel column.

[0018] Furthermore, step S4 specifically includes: S41: Begin construction of rigid platform units at the construction location of each rigid platform unit in the target construction zone; S42: Based on the excavation depth of the foundation pit, the parameters of each soil layer, the design load, the design horizontal resultant force, and the design parameters of the horizontal support bearing capacity, calculate and determine the number of vertical columns, spacing, the angle of the diagonal steel bracing, and the number of horizontal support layers to be arranged along the longitudinal and transverse directions of the foundation pit; clean the construction site and conduct surveying and layout, mark the center position of all vertical columns, and verify the specifications and hole positions of the precast components; S43: Vertical column construction: Construct the foundation at the marked location and hoist the vertical column, then fix it after correcting its verticality; the vertical column is a standard steel column; S44: Construction of horizontal support for the top floor: Install horizontal support for the top floor at the top of the vertical columns; S45: After the horizontal support of the top layer of the rigid platform unit at each construction location is completed, the first layer of standard steel component units is installed between the rigid platform units. The two ends of the first layer of standard steel component units are fixedly connected to the top layer of horizontal support and vertical column. S46: On the top floor plane formed by the horizontal support and vertical columns of the top floor and on the standard steel component unit, respectively lay matching prefabricated steel trestle panels. Using the prefabricated steel trestle panels as the construction platform, excavate the first layer of earthwork in the target construction zone. S47: After the first layer of earthwork is excavated to the set elevation, the horizontal support of the top layer is constructed and the horizontal support of the next layer is constructed. After the horizontal support of the rigid platform unit at each construction location is completed, the standard steel component unit of the second layer is installed between the rigid platform units. The prefabricated steel trestle plate of step S46 is used as the construction platform to excavate the second layer of earthwork in the target construction zone. S48: Following the steps of horizontal support construction, standard steel component unit construction, and earthwork excavation in step S47, excavate layer by layer downwards until the foundation is reached, forming an independent space around the rigid platform unit and the standard steel component unit.

[0019] Furthermore, in step S42, the number of vertical columns arranged along the longitudinal and transverse directions of the foundation pit... Determined by the following formula:

[0020] in, The design horizontal resultant force in this direction is calculated from the earth pressure. The design bearing capacity of the vertical column in this direction is calculated as that of a compression-bending member; Indicates rounding up; For any direction, the spacing between adjacent vertical columns satisfy:

[0021] in, Indicates the effective support width in this direction; The angle of the diagonal steel bracing The spacing between the longitudinal, transverse, and vertical columns in the orthogonal directions is determined, satisfying the following:

[0022] in, , The distance between two vertical columns in two mutually perpendicular directions; Number of horizontally supported layers Determined by the excavation depth of the foundation pit, satisfying:

[0023] in, This refers to the depth of the foundation pit excavation. The vertical design spacing for horizontal supports.

[0024] Furthermore, in step S45, the standard steel component unit includes several standard steel components, a channel steel cover plate, a triangular bracket, a connecting plate, and bolts. The triangular bracket is fixedly installed on the vertical column by welding or bolts. The lower flange of the standard steel component is fixedly connected to the top of the triangular bracket by welding or bolts. The upper flange of the standard steel component is fixedly connected to the vertical column by bolts. The standard steel components are fixedly connected to each other by connecting plates and bolts. The channel steel cover plate reinforces the connection between the standard steel components and the vertical column, as well as the connection between the standard steel components and the triangular bracket.

[0025] Furthermore, the standard steel component is provided with stiffening ribs.

[0026] Compared with the prior art, the present invention has the following technical effects: 1. In this invention, the method can flexibly cope with various irregular foundation pit shapes and complex zoning excavation schemes. It organizes construction by standard module zoning, forming a modular and standardized operation for ultra-large foundation pits. Each zoning is constructed independently and in an orderly manner, which significantly improves construction efficiency, shortens the total construction period, and makes the project progress, quality and safety risks highly controllable. It solves the safety and efficiency bottlenecks when zoning is changed, and truly achieves efficient response to ever-changing project needs with unchanging standardized modules.

[0027] 2. In this invention, the rigid platform unit and standard steel component unit on which this method relies have extremely high overall rigidity and precise deformation control, providing a safe working surface for all weather and all areas, eliminating the risks of high-altitude and cross-operations in traditional foundation pit construction; furthermore, through standardized, bolted connection design, non-recyclable concrete supports are replaced, all steel components are recyclable and reusable, the total life cycle cost is significantly reduced, and construction waste is almost zero, which meets the requirements of circular economy and sustainable development; in addition, a recycling system for rigid platform units and standard steel component units is constructed. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the standard steel support structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a rigid platform unit structure without prefabricated steel trestle decking, according to an embodiment of the present invention. Figure 3 This is a top view of the rigid platform unit according to an embodiment of the present invention; Figure 4 This is a front view schematic diagram of the rigid platform unit according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the assembled steel trestle platform according to an embodiment of the present invention; Figure 6 This is a top view of a standard steel component unit according to an embodiment of the present invention; Figure 7 This is a front view schematic diagram of a standard steel component unit according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the connection between the standard steel component unit and the vertical column in an embodiment of the present invention; Figure 9 This is a top view schematic diagram of the standard steel support structure in an ultra-large foundation pit according to an embodiment of the present invention.

[0029] In the diagram: 1. Rigid platform unit; 11. Horizontal support; 111. Diagonal steel brace; 112. Orthogonal steel brace; 12. Vertical column; 13. Prefabricated steel trestle plate; 2. Standard steel component unit; 21. Standard steel component; 22. Connecting plate; 23. Channel steel cover plate; 24. Triangular bracket; 25. Bolt; 26. Stiffening rib plate; 3. Extra-large foundation pit; 4. Construction zone. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0031] In this article, terms such as "left," "right," "up," "down," "front," and "back" are established based on the positional relationships shown in the attached drawings. Depending on the attached drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection.

[0032] This invention provides a modular foundation pit excavation construction method based on a standard steel support structure, comprising the following steps: S1: According to the construction organization schedule, based on the construction scope of the foundation pit and the area of ​​construction zone 4, several zoning lines are set along the horizontal direction of the foundation pit and several zoning lines are set along the vertical direction of the foundation pit. The zoning lines divide the entire foundation pit construction scope into several construction zones 4.

[0033] Specifically, in step S1, the spacing between adjacent zoning lines along the transverse direction of the foundation pit first satisfies:

[0034] in, This indicates the spacing between adjacent straight lines along the transverse direction of the foundation pit; This indicates the number of standard steel components 21, and is an integer. This indicates the modular length of a single section of standard steel component 21; Secondly, the spacing between adjacent zoning sections along the transverse direction of the foundation pit must also meet the following requirements:

[0035] in, This represents the maximum spacing between adjacent zonal lines along the transverse side of the foundation pit, calculated from the critical buckling pressure of rigid platform unit 1 after stability verification. This represents the elastic modulus of standard steel component 21; This represents the moment of inertia of section 21 of a standard steel member; This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components 21.

[0036] Furthermore, in step S1, the spacing between adjacent partition lines along the longitudinal direction of the foundation pit first satisfies:

[0037] in, This indicates the spacing between adjacent straight lines along the longitudinal direction of the foundation pit; This indicates the number of standard steel components 21, and is an integer. This indicates the modular length of a single section of standard steel component 21; Secondly, the spacing between adjacent zones along the longitudinal direction of the foundation pit must also meet the following requirements:

[0038] in, This represents the maximum spacing between adjacent partition lines along the longitudinal direction of the foundation pit, calculated from the critical buckling pressure of rigid platform unit 1 after stability verification. This represents the elastic modulus of standard steel component 21; This represents the moment of inertia of section 21 of a standard steel member; This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components 21.

[0039] Specifically, in step S1, construction zone 4 must be adapted to the physical operating range of earthmoving machinery, and the span of construction zone 4 along the transverse and longitudinal directions of the foundation pit must meet the following requirements:

[0040] in, This indicates the span of construction zone 4 along the transverse or longitudinal direction of the foundation pit; Indicates the effective operating radius; Effective operating radius The formula is:

[0041] in, Indicates the design depth of the foundation pit The critical operating radius below; This indicates the safe clearance between the standard steel component 21 and the bucket wall to prevent collisions, which is usually 500-800mm.

[0042] Guarantee span satisfy This ensures that the excavating machinery stationed on the rigid platform unit 1 can achieve full-coverage vertical excavation of the earthwork in construction zone 4 through opposing operations.

[0043] S2: The intersection of the transverse zoning line along the foundation pit and the longitudinal zoning line along the foundation pit is the construction location of rigid platform unit 1.

[0044] Specifically, such as Figures 2 to 5 As shown, in step S2, the rigid platform unit 1 includes multiple rows of vertical columns 12 and horizontal supports 11. The vertical columns 12 are arranged along the transverse and longitudinal directions of the foundation pit, forming a grid-like support system. The horizontal supports 11 and the vertical columns 12 are connected by node connection plates to achieve overall coordinated force bearing. In this embodiment, the vertical columns 12 are standard steel columns, suitable for situations where there is no main structure available in the foundation pit, to achieve convenience in processing and installation.

[0045] At least one layer of horizontal supports 11 is provided. The horizontal supports 11 include orthogonal steel supports 112 and diagonal steel supports 111. The orthogonal steel supports 112 orthogonally connect adjacent vertical columns 12, forming the main horizontal force transmission path. The diagonal steel supports 111 are located at the corners and diagonally connect to adjacent vertical columns 12 at the corners, used to enhance the overall torsional and lateral displacement resistance of the platform. The top layer of horizontal supports 11 and vertical columns 12 together form the top layer support plane. Prefabricated steel trestle decks 13 are laid on this plane, forming a smooth traffic route between the foundation pit and the external construction road. The prefabricated steel trestle decks 13 are connected to the upper flanges of the orthogonal steel supports 112 and diagonal steel supports 111, forming a working platform that allows construction machinery and personnel to pass through.

[0046] The prefabricated steel trestle panel 13 adopts an octagonal panel design, with lifting rings and assembly positioning holes integrated on the panel, which facilitates hoisting and rapid on-site positioning and installation, realizing modular construction.

[0047] The aforementioned rigid platform unit 1 simultaneously fulfills three major functions: structural support, traffic access, and working platform, realizing the concept of "structure as platform." Structurally, it participates in overall load-bearing as a horizontal support component; in terms of traffic, it serves as a transportation channel for construction vehicles and equipment; and operationally, it functions as a work platform for material storage and equipment operation. Furthermore, this rigid platform unit 1 can flexibly adapt to rectangular and irregular foundation pits, achieving full coverage by adjusting the number and angle of supports, and meeting diverse foundation pit layout requirements with standard modules.

[0048] S3: Based on the construction organization schedule, select at least one target construction zone 4 for simultaneous construction.

[0049] S4: Construction begins in target construction zone 4.

[0050] Specifically, step S4 includes: S41: Start construction of rigid platform unit 1 at the construction location of each rigid platform unit 1 in target construction zone 4; S42: Based on the excavation depth of the foundation pit, the parameters of each soil layer, the design load, the design horizontal resultant force, and the design parameters of the bearing capacity of the horizontal support 11, calculate and determine the number of vertical columns 12, the spacing, the installation angle of the diagonal steel braces 111, and the number of layers of horizontal support 11 to be arranged along the longitudinal and transverse directions of the foundation pit.

[0051] After completing the calculations, the construction site within the foundation pit was cleaned and leveled, and obstacles affecting the hoisting and installation of the steel structure were removed. Based on the calculation results, precise measurements and layout were conducted, and the center pile positions of all vertical columns 12 were marked on-site using equipment such as a total station. Simultaneously, the specifications, dimensions, reserved hole positions, and lifting rings of the prefabricated components (including horizontal supports 11, standard steel columns, node connection plates, and prefabricated steel trestle panels 13, etc.) were inspected and verified upon arrival at the site.

[0052] S43: Construction of Vertical Column 12 (Vertical Column 12 is a standard steel column): Construct a concrete independent foundation or pile cap at the marked pile location. After the foundation reaches its strength, use precast standard steel columns and a theodolite to correct the verticality of the columns, controlling the deviation within the allowable range specified in the code. After correction, firmly connect the lower end of the standard steel column to the foundation using column base anchor bolts.

[0053] S44: Construction of the top-level horizontal support 11: Install the top-level horizontal support 11 at the top of the vertical column 12.

[0054] Specifically, the process is as follows: the prefabricated transverse and longitudinal orthogonal steel supports 112 are hoisted to the designated position, with both ends aligned with the adjacent vertical columns 12. The ends of the orthogonal steel supports 112 are rigidly connected to the vertical columns 12 using high-strength bolts through node connection plates pre-welded to the vertical columns 12, or by welding on-site, to ensure that the nodes can transmit axial force, shear force, and bending moment.

[0055] After all orthogonal steel braces 112 are installed and tightened, diagonal steel braces 111 are installed at the four corners of the main load-bearing frame. Based on the angles calculated in step one, the diagonal steel braces 111 are hoisted into position, with one end connected to the vertical column 12 at the corner and the other end connected to the diagonally adjacent, distal vertical column 12. Rigid connections are made using the same node connection method (high-strength bolts or welding) as the orthogonal steel braces 112.

[0056] After the diagonal steel brace 111 is installed, it together with the orthogonal steel brace 112 and the vertical column 12 to form a closed support platform with strong lateral stiffness, which significantly improves the overall stability and torsional resistance of the platform.

[0057] S45: After the horizontal support 11 of the top layer of the rigid platform unit 1 at each construction location is completed, the first layer of standard steel component unit 2 is installed between the rigid platform units 1. The two ends of the first layer of standard steel component unit 2 are fixedly connected to the top layer of horizontal support 11 and vertical column 12.

[0058] S46: On the top-level plane formed by the horizontal support 11 and the vertical column 12, and on the standard steel component unit 2, compatible prefabricated steel trestle panels 13 are laid. In this embodiment, octagonal steel plates with stiffening ribs are preferred. The prefabricated steel trestle panels 13 are hoisted onto the top-level support plane formed by the horizontal support 11 and the vertical column 12. They are aligned with the reserved holes on the upper flanges of the orthogonal steel supports 112 and the diagonal steel supports 111 below through their pre-set holes, and then fixed with high-strength bolts to connect the orthogonal steel supports 112 and the diagonal steel supports 111 into a whole in the plane. The laid prefabricated steel trestle panels 13 form a continuous and flat construction platform, passageway, and working surface.

[0059] Safety signs such as fences are set up on the prefabricated steel trestle 13. Earthwork transport vehicles and excavation equipment use the prefabricated steel trestle 13 as the hub and the standard steel component unit 2 as the equipment movement area to excavate the first layer of earthwork in the target construction zone 4.

[0060] S47: After the first layer of earthwork is excavated to the set elevation, the horizontal support 11 of the next layer below the top layer of horizontal support 11 is constructed. After the horizontal support 11 of the rigid platform unit 1 at each construction position is completed, the standard steel component unit 2 of the second layer is installed between the rigid platform units 1. The prefabricated steel trestle 13 of step S46 is used as the construction platform to excavate the second layer of earthwork in the target construction zone 4. S48: Following the steps of horizontal support 11 construction, standard steel component unit 2 construction and earthwork excavation in step S47, excavate layer by layer downwards until the foundation is reached, forming an independent space around the rigid platform unit 1 and the standard steel component unit 2.

[0061] Specifically, in step S42, the number of vertical columns 12 arranged along the longitudinal and transverse directions of the foundation pit... Determined by the following formula:

[0062] in, The design horizontal resultant force in this direction is calculated from the earth pressure. The design bearing capacity of the vertical column 12 in this direction is calculated as a compression-bending member; Indicates rounding up; For any direction, the spacing between adjacent vertical columns 12 satisfy:

[0063] in, Indicates the effective support width in this direction; The angle of the diagonal steel brace 111 The spacing of the longitudinal, transverse, and vertical columns 12 in the orthogonal directions is determined, satisfying the following:

[0064] in, , The spacing between two vertical columns 12 in mutually perpendicular directions; Number of horizontal support layers 11 Determined by the excavation depth of the foundation pit, satisfying:

[0065] in, This refers to the depth of the foundation pit excavation. The vertical design spacing is for the horizontal support 11.

[0066] Specifically, such as Figures 6 to 8 As shown, in step S45, the standard steel component unit 2 includes several standard steel components 21, channel steel cover plates 23, triangular brackets 24, connecting plates 22, and bolts 25. In this embodiment, the standard steel component 21 with stiffening ribs 26 is preferred. One side of the triangular bracket 24 is aligned with the flange of the vertical column 12 and is fixedly installed on the vertical column 12 by welding or bolts 25. The lower flange of the standard steel component 21 contacts the top of the triangular bracket 24 and is fixedly connected by welding or bolts 25. The upper flange of the standard steel component 21 is fixedly connected to the vertical column 12 by bolts 25 to transfer shear force and bending moment. The standard steel components 21 are fixedly connected to each other by connecting plates 22 with evenly distributed holes and bolts 25. The evenly arranged bolts 25 help to distribute the load and avoid local stress concentration. The channel steel cover plate 23 is used to reinforce the connection between the standard steel component 21 and the vertical column 12, as well as the connection between the standard steel component 21 and the triangular bracket 24.

[0067] Specifically, such as Figure 1 and Figure 9 As shown, in the super-large foundation pit 3, four rigid platform units 1 and the standard support units connecting them together constitute a segmented standard steel support structure. This standard steel support structure is a statically indeterminate rigid frame. As an independent mechanical unit, this frame can independently bear the lateral water and soil pressure within the construction segment 4, allowing for full-depth foundation pit excavation and underground main structure construction within the construction segment 4, free from the progress restrictions of other areas of the foundation pit.

[0068] Specifically, the dimensions and components of the steel support structure in this standard can be flexibly adjusted according to project needs. For example, if a certain area needs to be used as a temporary material storage area according to the needs of the construction site, the local bearing capacity of the area can be quickly improved by adding standard steel components 21 and trestle plates in the local grid, so as to achieve dynamic adjustment of "space changes with demand".

[0069] S5: Repeat steps S3-S4 until the entire foundation pit construction area is completed.

[0070] S6: Following the modular reverse dismantling principle, dismantle and recycle rigid platform unit 1 and standard steel component unit 2.

[0071] Specifically, all dismantled components undergo flaw detection during recycling. The stress conditions and number of times each standard component is reused in this project are recorded before it is transferred to the next section or the next project, achieving true industrialized recycling.

[0072] Specifically, this method can flexibly handle various irregular foundation pit shapes and complex zoning excavation schemes. It organizes construction by standard modular zoning, forming a modular and standardized operation for the super-large foundation pit 3. Each zoning is constructed independently and relayed in an orderly manner, significantly improving construction efficiency, shortening the overall construction period, and making project progress, quality, and safety risks highly controllable. It solves the safety and efficiency bottlenecks during zoning transitions, truly achieving efficient response to ever-changing engineering needs with unchanging standardized modules. The rigid platform unit 1 and standard steel component unit 2, upon which this method relies, have extremely high overall rigidity and precise deformation control, providing a safe working surface for all weather conditions and all areas, eliminating the risks of high-altitude and cross-operations in traditional foundation pit construction. Furthermore, through standardized design and bolted 25 connections, it replaces non-recyclable concrete supports, making all steel components recyclable and reusable, significantly reducing the total life-cycle cost and reducing construction waste to near zero, meeting the requirements of circular economy and sustainable development. Additionally, it constructs a recycling system for the rigid platform unit 1 and standard steel component unit 2.

[0073] The above embodiments merely illustrate the basic principles and characteristics of the present invention, but are not limited to the above implementation schemes. It should be understood that those skilled in the art can make various changes and modifications to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modular foundation pit excavation construction method based on a standard steel support structure, characterized in that, Includes the following steps: S1: According to the construction organization schedule, based on the construction scope and construction zone (4) area of ​​the foundation pit, several zone lines are set along the horizontal direction of the foundation pit and several zone lines are set along the vertical direction of the foundation pit. The zone lines divide the entire foundation pit construction scope into several construction zones (4). S2: The intersection of the zoning line along the transverse direction of the foundation pit and the zoning line along the longitudinal direction of the foundation pit is the construction location of the rigid platform unit (1); The rigid platform unit (1) includes multiple rows of vertical columns (12) and horizontal supports (11). The horizontal supports (11) include orthogonal steel supports (112) and diagonal steel supports (111). The orthogonal steel supports (112) are orthogonally connected to adjacent vertical columns (12). The diagonal steel supports (111) are located at the corners and are diagonally connected to the adjacent vertical columns (12) at the corners. S3: According to the construction organization schedule, select at least one target construction zone (4) for simultaneous construction; S4: Construction begins in the target construction zone (4); Step S4 specifically includes: S41: Start construction of rigid platform unit (1) at the construction location of each rigid platform unit (1) in the target construction zone (4). S42: Based on the excavation depth of the foundation pit, the parameters of each soil layer, the design load, the design horizontal resultant force, and the design parameters of the bearing capacity of the horizontal support (11), calculate and determine the number and spacing of the vertical columns (12) to be laid along the longitudinal and transverse sides of the foundation pit, the laying angle of the diagonal steel bracing (111), and the number of layers of the horizontal support (11); clean up the construction site and conduct surveying and layout, mark the center position of all vertical columns (12), and verify the specifications and hole positions of the precast components; S43: Construction of vertical column (12): Construct the foundation at the marked location and hoist the vertical column (12), and fix it after correcting the verticality; the vertical column (12) is a standard steel column; S44: Construction of horizontal support (11) at the top: Install horizontal support (11) at the top of the vertical column (12). S45: After the horizontal support (11) of the top layer of the rigid platform unit (1) at each construction location is completed, the first layer of standard steel component unit (2) is installed between the rigid platform units (1), and the two ends of the first layer of standard steel component unit (2) are fixedly connected to the top layer of horizontal support (11) and vertical column (12). S46: On the top floor plane formed by the horizontal support (11) and the vertical column (12) of the top floor and the standard steel component unit (2), respectively, the matching prefabricated steel trestle (13) is laid, and the first layer of earthwork of the target construction zone (4) is excavated using the prefabricated steel trestle (13) as the construction platform. S47: After the first layer of earthwork is excavated to the set elevation, the horizontal support (11) of the top layer of construction is constructed. After the horizontal support (11) of the rigid platform unit (1) at each construction position is completed, the standard steel component unit (2) of the second layer is installed between the rigid platform units (1). The prefabricated steel trestle (13) of step S46 is used as the construction platform to excavate the second layer of earthwork in the target construction zone (4). S48: Following the steps of horizontal support (11) construction, standard steel component unit (2) construction and earthwork excavation in step S47, excavate layer by layer downwards until the foundation is reached, forming an independent space around the rigid platform unit (1) and the standard steel component unit (2). S5: Repeat steps S3-S4 until the entire foundation pit construction area is completed; S6: After construction is completed, the rigid platform unit (1) and the standard steel component unit (2) are dismantled and recycled.

2. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 1, characterized in that, In step S1, the spacing between adjacent zoning lines along the transverse direction of the foundation pit must first satisfy: in, This indicates the spacing between adjacent straight lines along the transverse direction of the foundation pit; The number of standard steel components (21) is an integer; Indicates the modular length of a single section of a standard steel component (21); Secondly, the spacing between adjacent zoning sections along the transverse direction of the foundation pit must also meet the following requirements: in, This represents the maximum spacing between adjacent zonal lines along the transverse side of the foundation pit, calculated from the critical instability pressure of the rigid platform element (1) after stability verification. The modulus of elasticity of the standard steel component (21) is indicated; Indicates the moment of inertia of the section of the standard steel member (21); This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components (21).

3. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 1, characterized in that, In step S1, the spacing between adjacent partition lines along the longitudinal direction of the foundation pit must first satisfy: in, This indicates the spacing between adjacent straight lines along the longitudinal direction of the foundation pit; The number of standard steel components (21) is an integer; Indicates the modular length of a single section of a standard steel component (21); Secondly, the spacing between adjacent zones along the longitudinal direction of the foundation pit must also meet the following requirements: in, This represents the maximum spacing between adjacent partition lines along the longitudinal direction of the foundation pit, calculated from the critical instability pressure of the rigid platform unit (1) after stability verification. The modulus of elasticity of the standard steel component (21) is indicated; Indicates the moment of inertia of the section of the standard steel member (21); This represents the stability coefficient of an axially compressed member. Indicates the safety factor; This indicates the average unit weight of the soil. Indicates the excavation depth; This indicates the horizontal spacing of standard steel components (21).

4. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 1, characterized in that, In step S1, the span of the construction zone (4) along the transverse and longitudinal directions of the foundation pit satisfies: in, The span of the construction zone (4) along the transverse or longitudinal direction of the foundation pit; Indicates the effective operating radius; Effective operating radius The formula is: in, Indicates the design depth of the foundation pit The critical operating radius below; This indicates the safe clearance between the standard steel component (21) and the bucket wall to prevent collisions.

5. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 1, characterized in that, In step S2, the vertical columns (12) are arranged along the horizontal and longitudinal directions of the foundation pit, and the horizontal support (11) is at least one layer. The top layer of the horizontal support (11) is fixedly installed on the top of the vertical columns (12). The top layer of the horizontal support (11) is covered with a prefabricated steel trestle plate (13). The prefabricated steel trestle plate (13) is connected to the upper flange of the orthogonal steel support (112) and the diagonal steel support (111).

6. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 5, characterized in that, The vertical column (12) is a standard steel column.

7. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 1, characterized in that, In step S42, the number of vertical columns (12) arranged along the longitudinal and transverse directions of the foundation pit is... Determined by the following formula: in, The design horizontal resultant force in this direction is calculated from the earth pressure. The design bearing capacity of the vertical column (12) in this direction is verified as that of a compression-bending member; Indicates rounding up; For any direction, the spacing between adjacent vertical columns (12) satisfy: in, Indicates the effective support width in this direction; The angle of the diagonal steel brace (111) The spacing of the longitudinal, transverse, and vertical columns (12) in the orthogonal directions is determined, satisfying: in, , The distance between two vertical columns (12) in mutually perpendicular directions; Number of layers of horizontal support (11) Determined by the excavation depth of the foundation pit, satisfying: in, This refers to the depth of the foundation pit excavation. The vertical design spacing for the horizontal support (11).

8. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 7, characterized in that, In step S45, the standard steel component unit (2) includes several standard steel components (21), channel steel cover plate (23), triangular bracket (24), connecting plate (22) and bolts (25). The triangular bracket (24) is fixedly installed on the vertical column (12) by welding or bolts (25). The lower flange of the standard steel component (21) is fixedly connected to the top of the triangular bracket (24) by welding or bolts (25). The upper flange of the standard steel component (21) is fixedly connected to the vertical column (12) by bolts (25). The standard steel components (21) are fixedly connected to each other by connecting plate (22) and bolts (25). The channel steel cover plate (23) reinforces the connection between the standard steel component (21) and the vertical column (12) as well as the connection between the standard steel component (21) and the triangular bracket (24).

9. The modular foundation pit excavation construction method based on a standard steel support structure according to claim 8, characterized in that, The standard steel component (21) is provided with stiffening ribs (26).

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