An upper-to-lower combined supporting system and construction method

Abstract

The application relates to a combined support system with upper normal and lower reverse and a construction method, which comprises a construction enclosure wall, a steel stand column and a stand column pile; a support structure is excavated and constructed layer by layer to the bottom of an interface layer, and an interface layer structure beam plate is poured; soil under the interface layer is excavated, an upper inclined support is erected, the lower end of the upper inclined support is connected with the enclosure wall through a ring beam, and the upper end is fixed to the top of the interface layer column through a corbel; a reserved soil platform is arranged at the pit edge, and the interior is excavated to the basement through a slope; a basement foundation bottom plate in a central island area is poured, a lower inclined support is erected, the upper end of the lower inclined support is connected with the enclosure wall through a ring beam, and the lower end is fixed to the column foot of the foundation bottom plate through a corbel; the reserved soil platform is removed, and a foundation bottom plate in a peripheral area is constructed; the underground structure is rebuilt, and the upper and lower inclined supports and the steel stand column are removed, so that the basement construction is completed. The application fully plays the respective advantages of the normal construction method and the reverse construction method through the excavation of the central island and the reserved soil at the pit edge and the support of the upper and lower inclined supports, the arrangement of the support stand column is reduced, the deformation of the foundation pit is effectively controlled, and the construction period is shortened.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering foundation pit support technology, and specifically relates to a combined top-forward and bottom-reverse support system and its construction method. Background Technology

[0002] Currently, there are two main construction methods in the field of foundation pit support and basement construction: the forward construction method and the reverse construction method. The forward construction method is technically mature, but a dedicated internal support system is required during excavation to withstand the lateral earth pressure of the retaining wall. For foundation pits with large plan dimensions, the large number of internal support components and the large amount of effective space occupied within the pit severely restrict the efficiency of earthwork excavation and underground structure construction. Furthermore, the forward construction method requires the completion of the entire underground structure before the construction of the superstructure can begin, resulting in a longer overall construction period. The reverse construction method utilizes permanent structural beams and slabs as supports, significantly reducing the amount of temporary internal supports required. Simultaneously, underground and above-ground structures can be constructed simultaneously, significantly shortening the overall project duration. However, the reverse construction method places higher demands on the vertical structure; columns must be positioned in one go and run through all floors, requiring high construction precision. In addition, the reverse construction environment is enclosed, resulting in relatively lower soil removal efficiency. In practical engineering, when there are significant differences in function between the upper and lower floors of a basement—that is, the upper floors have a small-span structure (such as residential buildings) and the lower floors have a large-span structure (such as garages)—the column grids of the vertical structures of the upper and lower floors are inconsistent and cannot be connected. Existing construction methods, such as the forward and reverse construction methods, are difficult to apply directly. Although there are combined construction methods that integrate forward and reverse construction, there is still a lack of systematic solutions for situations where the column grids of the upper and lower floors are inconsistent and the vertical structures are not connected. Significant technological gaps exist, particularly in areas such as the design of stress transfer at the interface layer and the coordination of synchronous construction between upper and lower areas.

[0003] Therefore, how to provide a combined top-clockwise and bottom-clockwise support system and construction method is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the shortcomings of traditional forward and reverse construction methods, this invention provides a combined forward and reverse support system and its construction method, thereby solving the technical problem that existing forward and reverse construction methods are difficult to apply when the column grid of the upper and lower floors of the basement is inconsistent and the vertical structure is not continuous.

[0005] To solve the above technical problems, the present invention includes the following technical solutions:

[0006] A combined top-clockwise and bottom-clockwise construction method, the construction method comprising:

[0007] Step S1: After leveling the site to the natural ground level, construct the retaining wall, engineering piles, steel columns and column piles: The steel columns and column piles, which serve as vertical support structures, are arranged in a one-column-one-pile manner according to the column grid of the upper construction area. The top of the steel columns is the structural beam slab of the basement top floor.

[0008] Step S2: Excavate the earthwork layer by layer and construct the support structure until the bottom of the interface layer: Since the steel columns and column piles in the upper continuous construction area are relatively dense, it is not easy to arrange the internal support. The external support structure is preferred; the internal support structure can also be used when the construction conditions permit.

[0009] Step S3: Casting the interface layer structural beams and slabs: The interface layer is the structural beam and slab separating the upper forward construction zone and the lower reverse construction zone. After the interface layer structural beams and slabs are constructed, the main structure is simultaneously constructed upwards in the upper forward construction zone during the construction of the lower reverse construction zone.

[0010] Step S4: After the interface layer structure reaches its strength, excavate the soil below the interface layer to the bottom of the upper inclined brace and erect the upper inclined brace: The upper inclined brace can be made of reinforced concrete or steel structure, and is arranged at intervals around the perimeter of the basement. The lower end is connected to the retaining wall through a ring beam, and the upper end is fixed to the top of the interface layer column through a corbel. The arrangement depth and spacing are determined according to calculation.

[0011] Step S5: After the upper inclined bracing is erected, a soil platform is reserved at the edge of the pit. The foundation pit is then excavated to the base with a slope: the width of the reserved soil platform at the edge of the pit is not less than 5m, the slope layer height is not greater than 4m, and the width of the platform between slopes is not less than 3m. One or more slopes are carried out according to the excavation depth.

[0012] Step S6: Pour the basement foundation slab in the central island area and erect the lower diagonal bracing: The lower diagonal bracing can be made of reinforced concrete or steel structure and is arranged at intervals around the perimeter of the basement. The upper end is connected to the retaining wall through a ring beam, and the lower end is fixed to the column base of the foundation slab through a corbel. The arrangement depth and spacing are determined by calculation.

[0013] Step S7: After the lower inclined bracing is erected, excavate the reserved soil platform at the edge of the pit and complete the construction of the foundation slab in the surrounding area;

[0014] Step S8: Rebuild the underground structures such as walls, columns, beams, and slabs. After they reach the design strength, remove the lower and upper diagonal braces, cut off the steel columns in the reverse construction area below, and complete the basement structure construction.

[0015] In particular, during the construction of the lower inverted construction area, care should be taken to protect the steel columns to avoid collisions and ensure the safety of the superstructure construction. If the lower inverted construction area has a multi-story basement structure, it can be excavated to the foundation in steps 4 to 7, and then backfilled layer by layer in step 8.

[0016] The present invention also provides a support system for the above-clockwise and counterclockwise combined construction method, comprising:

[0017] A retaining wall shall be constructed around the perimeter of the foundation pit;

[0018] The vertical support system includes steel columns and column piles, which are arranged in a one-column-one-pile manner according to the column grid of the upper construction zone. The top of the steel columns is connected to the structural beams and slabs of the top floor of the basement.

[0019] The interface layer structural beam and slab are located at the boundary between the upper forward-operating zone and the lower reverse-operating zone;

[0020] Upper diagonal bracing is arranged at intervals around the perimeter of the basement below the structural beams and slabs of the interface layer. The upper end of the upper diagonal bracing is fixed to the top of the interface layer column by a corbel, and the lower end of the upper diagonal bracing is connected to the enclosure wall by a ring beam.

[0021] The basement foundation slab in the central island area is located in the central area of ​​the foundation pit;

[0022] The lower diagonal bracing is arranged at intervals around the perimeter of the basement above the basement foundation slab in the central island area. The lower end of the lower diagonal bracing is fixed to the column base of the foundation slab by corbels, and the upper end of the lower diagonal bracing is connected to the enclosure wall by a ring beam.

[0023] The foundation slab for the surrounding area is located in the area surrounding the foundation pit, outside the basement foundation slab of the central island area.

[0024] The supporting structure is located on the outside or inside of the upper working area enclosure wall.

[0025] Furthermore, both the upper and lower diagonal braces are reinforced concrete diagonal braces or steel diagonal braces. Furthermore, when the dense steel columns and column piles in the upper continuous construction zone make it difficult to arrange internal supports, the support structure adopts an external support structure; when construction conditions permit, the support structure adopts an internal support structure.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) The combined construction method of upper-forward and lower-reverse construction provided by the present invention uses the interface layer as a force conversion structure, which solves the problem that traditional forward or reverse construction cannot be used when the vertical structures of the upper and lower layers are not connected, broadens the scope of application of the reverse construction method, and solves the construction problem when the column grid of the upper and lower layers is inconsistent.

[0028] (2) The combined support system of upper and lower diagonal bracing provided by the present invention replaces the support system that is difficult to arrange in large open-plan floors, effectively bears the lateral earth pressure of the retaining wall, ensures construction safety, and the force of the diagonal bracing system is clear and can be quantified, which greatly reduces the support difficulty of large open-plan floors.

[0029] (3) The combined construction method of upper-forward and lower-reverse construction provided by the present invention allows for simultaneous upward construction of the structure after the interface layer is completed. Both forward and reverse construction areas, above ground and underground can be operated in parallel, which can significantly shorten the construction period compared with the traditional all-forward construction method.

[0030] (4) The combined support system of upper-forward and lower-reverse construction provided by the present invention allows for flexible selection of external or internal support schemes for the upper forward construction zone according to site conditions, and the diagonal bracing of the lower reverse construction zone can be made of various materials such as reinforced concrete or steel, which is highly adaptable. In addition, compared with the full reverse construction method, the lower reverse construction zone does not need to be equipped with dense vertical structures as required by the reverse construction method. Compared with the full forward construction method, it reduces a large number of internal support components, resulting in significant comprehensive economic benefits. Attached Figure Description

[0031] Figure 1 This is a cross-sectional schematic diagram of an embodiment of the combined top-forward and bottom-reverse support system of the present invention;

[0032] Figures 2 to 9 This is a schematic flowchart of a top-clockwise and bottom-clockwise combined construction method according to an embodiment of the present invention.

[0033] 1-Retaining wall, 2-Engineering pile, 3-Steel column, 4-Column pile, 5-Upper diagonal brace, 6-Lower diagonal brace, 7-Supporting structure, 8-Interface layer, 9-Basement foundation slab of central island area, 10-Foundation slab of surrounding area, 11-Reserved soil platform at pit edge, 12-Bottom of interface layer, 13-Bottom of upper diagonal brace, 14-Base, 15-Upper forward construction zone, 16-Lower reverse construction zone. Detailed Implementation

[0034] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more detailed explanation of the combined top-clockwise and bottom-clockwise support system and construction method provided by the present invention. The advantages and features of the present invention will become clearer from the following description.

[0035] The following is combined with Figures 1 to 9 This invention provides a detailed description of the top-clockwise and bottom-clockwise combined support system and its construction method.

[0036] Example 1

[0037] Please refer to Figures 1 to 9 A combined top-clockwise and bottom-clockwise construction method, the construction method comprising:

[0038] Step S1: After leveling the site to the natural ground level, construct the retaining wall 1, engineering piles 2, steel columns 3 and column piles 4: The steel columns 3 and column piles 4, which serve as vertical support structures, are arranged in a one-column-one-pile manner according to the column grid of the upper construction zone 15. The top of the steel column 3 is the top structural beam slab of the basement.

[0039] Step S2: Excavate the earthwork layer by layer and construct the support structure 7 until the bottom of the interface layer 12: Since the steel columns 3 and column piles 4 in the upper working area 15 are relatively dense, it is not easy to arrange the internal support. The external support structure is preferred; the internal support structure can also be used when the construction conditions permit.

[0040] Step S3: Pouring the interface layer 8 structural beams and slabs: Interface layer 8 is the boundary layer structural beams and slabs between the upper forward construction zone 15 and the lower reverse construction zone 16. After the interface layer structural beams and slabs are constructed, the main structure can be constructed simultaneously upwards in the upper forward construction zone 15 during the construction of the lower reverse construction zone 16.

[0041] Step S4: After the interface layer 8 reaches structural strength, excavate the soil below the interface layer to the bottom 13 of the upper inclined brace and erect the upper inclined brace 5. The upper inclined brace 5 can be made of reinforced concrete or steel structure and is arranged at intervals around the perimeter of the basement. The lower end is connected to the retaining wall 1 through a ring beam, and the upper end is fixed to the top of the interface layer column through a corbel. The arrangement depth and spacing are determined according to calculation.

[0042] Step S5: After the upper inclined brace 5 is erected, a soil platform 11 is reserved at the edge of the pit, and the interior is excavated to the base 14 with an internal slope. The width of the soil platform 11 reserved at the edge of the pit is not less than 5m, the slope layer height is not greater than 4m, the width of the platform between slopes is not less than 3m, and one or more slopes are carried out according to the excavation depth.

[0043] Step S6: Pour the basement foundation slab 9 in the central island area and erect the lower diagonal bracing 6: The lower diagonal bracing 6 can be made of reinforced concrete or steel structure and is arranged at intervals around the perimeter of the basement. The upper end is connected to the retaining wall 1 through a ring beam, and the lower end is fixed to the column base of the foundation slab through a corbel. The arrangement depth and spacing are determined according to calculation.

[0044] Step S7: After the lower inclined brace 6 is erected, the reserved soil platform 11 at the edge of the pit is excavated, and the foundation slab 10 of the surrounding area is completed.

[0045] Step S8: Rebuild the underground structure, including walls, columns, beams, and slabs. After the structure reaches the design strength, remove the lower diagonal brace 6 and the upper diagonal brace 5, and cut off the steel column 3 in the lower reverse construction area 16 to complete the basement structure construction.

[0046] In particular, during the construction of the lower reverse construction zone 16, care should be taken to protect the steel columns 3 to avoid collisions and ensure the safety of the upper structure construction. If the lower reverse construction zone 16 has a multi-story basement structure, it can be excavated to the foundation in steps 4 to 7, and then backfilled layer by layer in step 8.

[0047] Please continue to refer to this. Figures 1 to 9 The present invention also provides a support system for the above-clockwise and below-clockwise combined construction method, comprising:

[0048] Retaining wall 1, set up around the perimeter of the foundation pit;

[0049] The vertical support system includes steel columns 3 and column piles 4. The steel columns 3 and column piles 4 are arranged in a one-column-one-pile manner according to the column grid of the upper construction zone 15. The top of the steel column 3 is connected to the structural beams and slabs of the top floor of the basement.

[0050] The interface layer 8 structural beams and slabs are located at the boundary between the upper forward-operating zone 15 and the lower reverse-operating zone 16.

[0051] The upper diagonal brace 5 is arranged at intervals around the perimeter of the basement below the structural beams and slabs of the interface layer 8. The upper end of the upper diagonal brace 5 is fixed to the top of the column of the interface layer by a corbel, and the lower end of the upper diagonal brace 5 is connected to the retaining wall 1 by a ring beam.

[0052] The basement foundation slab 9 of the central island area is located in the central area of ​​the foundation pit;

[0053] The lower diagonal brace 6 is arranged at intervals around the perimeter of the basement above the basement foundation slab 9 in the central island area. The lower end of the lower diagonal brace 6 is fixed to the column base of the foundation slab by a corbel, and the upper end of the lower diagonal brace 6 is connected to the retaining wall 1 by a ring beam.

[0054] The foundation slab 10 of the surrounding area is located in the area surrounding the foundation pit, outside the basement foundation slab 9 of the central island area.

[0055] Support structure 7 is located on the outside or inside of the enclosure wall of the upper working area 15.

[0056] In this embodiment, more preferably, both the upper diagonal brace 5 and the lower diagonal brace 6 are reinforced concrete diagonal braces or steel diagonal braces.

[0057] More preferably, the support structure 7 is an external support structure when the steel columns 3 and column piles 4 in the upper continuous construction area 15 are densely packed, making it difficult to arrange the internal support; when the construction conditions permit, an internal support structure can be used.

[0058] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A combined top-clockwise and bottom-counterclockwise construction method, characterized in that, The construction method includes: Step S1: After the site is leveled to the natural ground level, the construction of the retaining wall, engineering piles, steel columns and column piles is carried out; the steel columns and column piles serve as vertical support structures and are arranged in a one-column-one-pile manner according to the column grid of the upper construction area. The top of the steel columns is the top structural beam and slab of the basement. Step S2: Excavate the earthwork layer by layer and construct the supporting structure until the bottom of the interface layer is reached; the interface layer is the boundary layer structure beam and slab between the upper forward-operating zone and the lower reverse-operating zone. Step S3: Pour the interface layer structural beams and slabs; after the interface layer structural beams and slabs are constructed, during the construction of the lower reverse construction zone, the upper forward construction zone will simultaneously construct the main structure upwards. Step S4: After the interface layer structural beams and slabs reach the design strength, excavate the soil below the interface layer to the bottom elevation of the upper inclined brace and erect the upper inclined brace; the upper inclined brace is arranged at intervals around the perimeter of the basement, the lower end of the upper inclined brace is connected to the retaining wall through a ring beam, and the upper end of the upper inclined brace is fixed to the top of the interface layer column through a corbel. Step S5: After the upper inclined bracing is erected, a soil platform is reserved at the edge of the pit, and the pit is excavated with a slope to the design elevation of the foundation. Step S6: Pour the basement foundation slab in the central island area and erect the lower diagonal bracing; the lower diagonal bracing is arranged at intervals around the perimeter of the basement, the upper end of the lower diagonal bracing is connected to the retaining wall through a ring beam, and the lower end of the lower diagonal bracing is fixed to the column base of the foundation slab through a corbel. Step S7: After the lower inclined bracing is erected, excavate the reserved soil platform at the edge of the pit and construct the foundation slab in the surrounding area. Step S8: Rebuild the underground structure of walls, columns, beams and slabs. After the design strength is reached, remove the lower and upper diagonal braces, cut off the steel columns in the reverse construction area below, and complete the construction of the basement structure.

2. The construction method according to claim 1, characterized in that, In step 2, the support structure is an external support structure when the steel columns and column piles in the upper continuous construction area are dense, making it difficult to arrange the internal support; when the construction conditions permit, an internal support structure is used.

3. The construction method according to claim 1, characterized in that, The upper and lower diagonal braces are reinforced concrete or steel diagonal braces, and the arrangement depth and spacing of the upper and lower diagonal braces are determined based on the foundation pit calculation.

4. The construction method according to claim 1, characterized in that, In step 5, the width of the reserved earth platform at the edge of the pit shall not be less than 5m, the slope shall be laid in layers, the layer height shall not be greater than 4m, the width of the platform between slopes shall not be less than 3m, and one or more slopes shall be laid according to the depth of the pit.

5. A support system for the combined top-forward and bottom-reverse construction method according to any one of claims 1 to 4, characterized in that, include: A retaining wall shall be constructed around the perimeter of the foundation pit; The vertical support system includes steel columns and column piles, which are arranged in a one-column-one-pile manner according to the column grid of the upper construction zone. The top of the steel columns is connected to the structural beams and slabs of the top floor of the basement. The interface layer structural beam and slab are located at the boundary between the upper forward-operating zone and the lower reverse-operating zone; Upper diagonal bracing is arranged at intervals around the perimeter of the basement below the structural beams and slabs of the interface layer. The upper end of the upper diagonal bracing is fixed to the top of the interface layer column by a corbel, and the lower end of the upper diagonal bracing is connected to the enclosure wall by a ring beam. The basement foundation slab in the central island area is located in the central area of ​​the foundation pit; The lower diagonal bracing is arranged at intervals around the perimeter of the basement above the basement foundation slab in the central island area. The lower end of the lower diagonal bracing is fixed to the column base of the foundation slab by corbels, and the upper end of the lower diagonal bracing is connected to the enclosure wall by a ring beam. The foundation slab for the surrounding area is located in the area surrounding the foundation pit, outside the foundation slab of the basement in the central island area; The supporting structure is located on the outside or inside of the upper working area enclosure wall.

6. The support system according to claim 5, characterized in that, Both the upper and lower diagonal braces are reinforced concrete diagonal braces or steel diagonal braces.

7. The support system according to claim 5, characterized in that, When the steel columns and column piles in the upper continuous construction area are densely packed, making it difficult to arrange the internal supports, the support structure adopts an external support structure; when construction conditions permit, the support structure adopts an internal support structure.

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