Deep foundation pit support structure

Abstract

The utility model discloses a kind of deep foundation pit replacement support structure, including deep foundation pit, mixing pile, bored pile and the steel structure column being arranged in the interior of mixing pile and bored pile, still including construction crown beam and the first support beam of the fixed connection with the construction crown beam;Waist beam and the second support beam of the fixed connection with the waist beam, the waist beam and the second support beam are connected as an organic whole by embedded steel bar, first support beam and remove first support beam by prior construction, the replacement support of deep foundation pit is realized, and by integrated pouring basement outer wall and waist beam and second support beam, the improvement of good stress dispersion and waterproof performance of basement outer wall is realized.

Description

Technical Field

[0001] This utility model relates to the field of building construction, specifically to a deep foundation pit replacement support structure during basement construction. Background Technology

[0002] During the construction process, construction projects are often difficult to implement due to limitations of the construction environment, such as foundation pits and basements, or the construction project may deform due to changes in the environment. Therefore, construction support is particularly important.

[0003] During construction, the inventor discovered that, upon dissecting and studying existing methods, due to land constraints, the theoretical distance from the outer wall of a basement to the location of the support piles was 1 meter. However, in actual construction, the diameter of most of the support piles was 20-80 cm larger than the theoretical value, and there was no space for sloping in the deep foundation pit.

[0004] The common method for resolving conflicts between internal bracing in deep foundation pits and buildings is the existing construction method of pre-reserved openings in the side walls: After excavating the deep foundation pit to the bottom, construct the structural base slab and external walls and pilasters of a certain height; pour a 500mm thick C25 plain concrete force transfer strip on the base slab surface. After the force transfer strip reaches its design strength, construct the structural external walls, pilasters, and top slab, reserving openings at the wall penetration locations for the supports, until the underground structure is completed. Backfill the side trench of the deep foundation pit with plain soil up to the bottom surface of the first internal support beam, with a compaction degree ≥0.94 and not exceeding the architectural and structural requirements. Pour a 500mm thick C25 plain concrete force transfer strip on the top slab surface. After the force transfer strip reaches its design strength, remove the reinforced concrete internal bracing. However, research has found that when this method is used to fill the pre-reserved holes in the side wall, the subsequent waterproofing work is difficult due to the large number of holes left in the side wall. Furthermore, the large number of holes may cause the structural strength of the wall to fail to meet the construction requirements. In addition, the waist beam supported by the support beam on the support pile occupies part of the space between the support pile and the side wall. If the diameter of the support pile is too large during the pouring process, the space between the waist beam and the side wall cannot guarantee the construction operation space required for subsequent formwork, scaffolding, and earthwork backfilling.

[0005] A typical existing technology, such as CN114908759A, discloses a method for constructing foundation pits around existing underground structures. This method involves first constructing a retaining structure, which, together with the underground structure, forms a closed area. Simultaneously, the first-stage foundation pit area and stress relief trenches on both sides of the underground structure are constructed. This avoids the risk of displacement of the underground structure due to unilateral soil pressure, reduces the time and cost of setting external supports within the foundation pit, and avoids constraints on subsequent building design. A solidification structure is constructed within the foundation pit area on the side closest to the underground structure to reinforce it and reduce displacement during later excavation. Several temporary supports are installed within the underground structure to reinforce it and prevent deformation or cracking. During the construction of the foundation pit to the bottom, a portion of the soil layer is retained to form a reserved soil platform on the side closest to the underground structure to protect it and reduce the exposure time of the foundation pit. After removing the reserved soil platform, the foundation pit excavation is complete. However, a problem with this method is that it mainly supports the surrounding area of ​​the building, lacking support for the floor slabs of the underground structure, which can lead to risks during the construction of the underground structure.

[0006] For example, the article "Application of Using Main Structural Columns to Form a System for Replacing (Removing) Braces in Foundation Pit Support," published in the December 2023 supplement of *Architectural Structure*, by Xiong Haiming et al., discloses two options for basement construction: First, install diagonal bracing beams, with one end resting under the beam to be removed and the other end resting on the floor slab. After removing the original support beam, the stress is transferred to the floor slab through the diagonal bracing beams. Second, utilize the completed main structural columns to reconstruct a more rigid system and install steel pipe braces for replacement. Considering the long construction period and high cost of the first option, the second option was ultimately chosen. However, this option lacks support for the central building structure, potentially leading to the building not meeting relevant requirements in unstable building environments.

[0007] Based on the above-mentioned technical problems, in order to solve the technical problems of insufficient construction operation space required for supporting the formwork, frame, and earthwork backfilling in the existing technology, as well as the technical problems affecting the wall structure and waterproof performance, the inventors proposed a deep foundation pit replacement support structure. Utility Model Content

[0008] The purpose of this invention is to provide a deep foundation pit replacement support structure to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A deep foundation pit replacement support structure includes a deep foundation pit, mixing piles, cast-in-place piles, and steel columns installed inside the mixing piles and cast-in-place piles, a shear wall, a construction cap beam and a first support beam fixedly connected to the construction cap beam; a waist beam and a second support beam fixedly connected to the waist beam.

[0010] Furthermore, both the first and second support beams are removable structures.

[0011] A further improvement of this utility model is that the shear wall is the outer wall of a deep foundation pit basement.

[0012] A further improvement of this utility model is that: the construction cap beam and the first support beam are set at the top of the deep foundation pit; the waist beam and the second support beam are set in the middle of the deep foundation pit; and the waist beam and the second support beam are set flush with each other.

[0013] A further improvement of this utility model is that it also includes support columns located at the edge of the deep foundation pit.

[0014] A further improvement of the present invention is that the deep foundation pit also includes a basement floor slab, which is a cast-in-place floor slab, and the floor slab and the support columns at the edge of the deep foundation pit are fixedly connected by cast plain concrete replacement support plates.

[0015] A further improvement of this utility model is that: an outer wall is provided on the edge of the basement floor slab, and a second support beam and a waist beam are provided in the middle of the outer wall. The waist beam is provided on the outside of the outer wall, and the second support beam is provided on the inside of the outer wall.

[0016] A further improvement of this utility model is that: the second support beam, the basement exterior wall, and the waist beam are connected as a whole by pre-embedded steel bars and formed by integral concrete pouring; further, one end of the second support beam is fixedly connected to the waist beam on the outside of the basement exterior wall, and the other end is fixedly connected to the cast-in-place pile; further, the height of the second support beam from the basement floor slab is 1 / 3 to 2 / 3 of the height of the first basement floor.

[0017] A further improvement of this utility model is that the outer wall of the basement is provided with filling material.

[0018] A further improvement of this utility model is that: the first support beam is fixedly connected to the top of the basement exterior wall, the basement top is poured on the first support beam, the bottom of the first support beam is 40-100cm higher than the secondary floor slab, and the secondary floor slab avoids conflict between the first support beam and the building.

[0019] The further improvement of this utility model technical solution is that the construction is carried out by the following construction steps: S1, leveling the site inside the deep foundation pit and constructing mixing piles, cast-in-place piles and steel structure columns, etc. S2, construct the cap beam and the first support beam, and install a force transmission belt on the upper part of the first support beam; S3, excavate the earth to the bottom of the foundation pit, pour the bottom slab, and pour plain concrete replacement support plate between the bottom slab and the support piles; S4, the height of the construction of the basement exterior wall to the bottom of the second support beam, wherein the construction height of the basement exterior wall is 1 / 3 to 2 / 3 of the distance from the basement floor slab to the basement top; S5, fill the space between the mixing pile and the basement floor slab, with the filling height being 20-30cm higher than the height of the basement floor slab; connect the lintel beam, the basement exterior wall and the second support beam by pre-embedded steel bars, and simultaneously pour the basement exterior wall, lintel beam and the second support beam.

[0020] Furthermore, after the poured basement exterior walls, lintels, and second support beams have reached their design strength, the first support beam at the cap beam location is removed.

[0021] Continue constructing the basement exterior walls up to the basement roof slab. Use methods such as pouring concrete to construct the basement roof slab. After completing the basement construction, remove the second support beam. Remove and cut the connection between the second support beam and the basement exterior walls. Apply waterproofing treatment to the cross-section to ensure the integrity of the basement exterior walls and prevent stress concentration and reduced waterproofing.

[0022] Due to the adoption of the above technical solution, the beneficial technical progress achieved by this utility model compared to the prior art is as follows: 1. By setting up a first support beam and a second support beam, the construction space can be guaranteed while avoiding the problem of insufficient construction space due to insufficient space for the support beam. It is suitable for foundation pits with narrow surrounding areas and lack of storage space for materials and machinery. It is also suitable for any foundation where blasting is permitted.

[0023] 2. By removing the first support beam first and then the second support beam, the construction accuracy of the basement building can be guaranteed, and the deformation of the building caused by changes in the geographical environment of the deep foundation pit can be avoided. It is suitable for the construction of deep foundation pits and ultra-deep basement foundation pits in soft soil, and is suitable for foundation pit construction in areas where pipelines are buried around the foundation pit, environmental protection requirements are high, surrounding buildings are close, and the earthwork schedule is tight. It is also suitable for foundation pits where cranes cannot be in place for support and hoisting.

[0024] 3. The integrated casting of the second support beam can avoid stress concentration problems caused by the removal of holes in the basement exterior wall after the removal of the second support beam, and also avoid the problem of poor waterproofing of the basement caused by the setting of holes in the basement exterior wall. Attached Figure Description

[0025] Figure 1 This is one of the schematic diagrams of the structural construction steps of this utility model; Figure 2 This is the second schematic diagram of the structural construction steps of this utility model; Figure 3 This is the third schematic diagram of the structural construction steps of this utility model; Figure 4 This is the fourth schematic diagram of the structural construction steps of this utility model.

[0026] The attached diagram is labeled as follows: 1. Deep foundation pit; 2. Mixing pile; 3. Cast-in-place pile; 4. Steel column; 5. Crown beam; 6. First support beam; 7. Basement floor slab; 8. Support column; 9. Basement exterior wall; 10. Infill; 11. Waist beam; 12. Intersection of basement exterior wall and second support beam; 13. Second support beam; 14. Basement roof slab. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to embodiments: Example

[0028] like Figure 1-4 As shown, this utility model provides a deep foundation pit replacement support structure, including a deep foundation pit 1, a mixing pile 2, a cast-in-place pile 3, and a steel column 4 installed inside the mixing pile 2 and the cast-in-place pile 3. It also includes a construction cap beam 5 and a first support beam 6 fixedly connected to the construction cap beam 5; a waist beam 11 and a second support beam 13 fixedly connected to the waist beam 11. The waist beam 11 and the second support beam have an intersection 12 of the basement exterior wall and the second support beam.

[0029] The construction cap beam 5 and the first support beam 6 are set at the top of the deep foundation pit 1; the waist beam 11 and the second support beam 13 are set in the middle of the deep foundation pit 1; the waist beam 11 and the second support beam 13 are set flush with each other.

[0030] It also includes the support columns 8 located at the edge of the deep foundation pit 1.

[0031] The deep foundation pit 1 also includes a basement floor slab 7, which is a cast-in-place floor slab. The basement floor slab 7 and the support columns 8 at the edge of the deep foundation pit 1 are fixedly connected by cast plain concrete support plates.

[0032] The basement floor slab 7 has an outer wall 9 extending upwards from its edge. A waist beam 11 and a second support beam 13 are provided in the middle of the outer wall 9. The waist beam 11 is located on the outer side of the outer wall 9, and the second support beam 13 is located on the inner side of the outer wall 9.

[0033] The second support beam 13, the basement exterior wall 9, and the waist beam 11 are connected as one unit by pre-embedded steel bars and formed by integral concrete pouring. One end of the second support beam 13 is fixedly connected to the waist beam 11 on the outside of the basement exterior wall 9, and the other end is fixedly connected to the cast-in-place pile 3. Further, the height of the second support beam 11 from the basement floor slab 7 is 1 / 3 to 2 / 3 of the height of the first basement floor.

[0034] The first support beam 6 is fixedly connected to the top of the basement exterior wall 9. The basement top 14 is poured on the first support beam 6. The bottom of the first support beam 6 is 40-100cm higher than the secondary floor slab surface. The secondary floor slab surface avoids the conflict between the first support beam 6 and the building structure.

[0035] Furthermore, this new invention is constructed using the following steps: S1, Level the site inside the deep foundation pit 1, and construct mixing piles 2, cast-in-place piles 3 and steel columns 4, etc. S2, construct the cap beam 5 and the first support beam 6, and install a force transmission belt on the upper part of the first support beam 6; S3, excavate the earth to the bottom of the deep foundation pit 1, pour the basement floor slab 7, and pour plain concrete replacement support slab between the basement floor slab 7 and the support piles 8. S4, the height from the basement exterior wall 9 to the bottom of the second support beam 13, wherein the construction height of the basement exterior wall 13 is 1 / 3 to 2 / 3 of the height from the basement floor 7 to the basement top 14; S5, filler 10 is set between the mixing pile 2 and the basement floor 7. The height of filler 10 is 20-30cm higher than the height of the basement floor 7, while filler 10 is lower than the height of the basement exterior wall 9. The waist beam 11, the basement exterior wall 9 and the second support beam 13 are connected by pre-embedded steel bars. At the same time, the basement exterior wall 9, waist beam 11 and the second support beam 13 are poured.

[0036] Furthermore, after the poured basement exterior wall 9, waist beam 11 and second support beam 13 have reached their design strength, the first support beam 6 at the position of the cap beam 5 is removed.

[0037] Continue construction of the basement exterior wall 9 to the basement roof slab 14. Use methods such as pouring to construct the basement roof slab. After the basement construction is completed, remove the second support beam 13. Remove and cut the connection between the second support beam 13 and the basement exterior wall 9. Waterproofing treatment is carried out at the cross-section to ensure the integrity of the basement exterior wall 9 and prevent stress concentration and reduced waterproofing.

[0038] The above-mentioned deep foundation pit support structure can achieve the following advantages: By setting up a first support beam and a second support beam, the construction space can be guaranteed while avoiding the problem of insufficient construction space due to insufficient space for the support beam. It is suitable for foundation pits with narrow surrounding areas and lack of storage space for materials and machinery, and is suitable for any foundation where blasting is permitted.

[0039] By removing the first support beam first and then the second support beam, the construction accuracy and stability of the basement building can be guaranteed, and the deformation of the building caused by changes in the geographical environment of the deep foundation pit can be avoided. It is suitable for the construction of deep foundation pits and ultra-deep basement foundation pits in soft soil, and is suitable for foundation pit construction in areas where pipelines are buried around the foundation pit, environmental protection requirements are high, surrounding buildings are close, and the earthwork schedule is tight. It is also suitable for foundation pits where cranes cannot be positioned to provide support and hoisting.

[0040] The integrated casting of the second support beam, exterior wall, and lintel can avoid stress concentration problems caused by the removal of holes in the basement exterior wall after the removal of the second support beam, and also avoid the problem of poor waterproofing of the basement caused by the presence of holes in the basement exterior wall.

[0041] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the protection scope of the present invention.

Claims

1. A deep foundation pit replacement support structure, comprising a deep foundation pit, mixing piles, cast-in-place piles, and steel columns and shear walls disposed inside the mixing piles and cast-in-place piles, characterized in that: It also includes a construction cap beam and a first support beam fixedly connected to the construction cap beam; a waist beam and a second support beam fixedly connected to the waist beam. The waist beam, the second support beam, and the shear wall are connected as a whole by pre-embedded steel bars. The cap beam and the first support beam are constructed and demolished first, and then the waist beam and the second support beam are constructed and demolished.

2. The deep foundation pit replacement support structure according to claim 1, characterized in that: The construction cap beam and the first support beam are set at the top of the deep foundation pit; the waist beam and the second support beam are set in the middle of the deep foundation pit; the waist beam and the second support beam are set flush with each other.

3. The deep foundation pit replacement support structure according to claim 2, characterized in that: It also includes support columns located at the edge of deep foundation pits.

4. The deep foundation pit replacement support structure according to claim 1, characterized in that: The deep foundation pit also includes a basement floor slab, which is a cast-in-place floor slab. The floor slab and the support columns at the edge of the deep foundation pit are fixedly connected by cast-in-place plain concrete support plates.

5. A deep foundation pit replacement support structure according to claim 4, characterized in that: A shear wall is provided at the edge of the basement floor slab, which serves as the basement exterior wall. A second support beam and a wainscoting are provided in the middle of the basement exterior wall. The wainscoting is located on the outer side of the basement exterior wall, and the second support beam is located on the inner side of the basement exterior wall.

6. A deep foundation pit replacement support structure according to claim 5, characterized in that: The second support beam is located at a height of 1 / 3 to 2 / 3 of the height of the first basement floor.

7. A deep foundation pit replacement support structure according to claim 5, characterized in that: The second support beam, the basement exterior wall, and the waist beam are connected as one unit by pre-embedded steel bars and formed by integral concrete pouring.

8. A deep foundation pit replacement support structure according to claim 5, characterized in that: The first support beam is fixedly connected to the top of the basement exterior wall. The basement top is poured on the first support beam, and the bottom of the first support beam is 40-100cm higher than the surface of the secondary floor slab.

9. A deep foundation pit replacement support structure according to claim 1, characterized in that: Both the first and second support beams are removable structures.

10. A deep foundation pit replacement support structure according to claim 5, characterized in that: The exterior walls of the basement are filled with infill material.

Images