Demolition and replacement method for horizontal inner support of deep foundation pit

Abstract

The invention discloses a deep foundation pit horizontal inner support dismantling and replacing method. The method comprises the following steps that a bottom layer support replacing plate is constructed between a raft foundation floor slab and a support pile; constructing a structural floor slab and a structural external wall panel of the layer, and constructing a top crotch support changing plate between the support pile and the structural external wall panel of the layer; if the building structure of a certain layer and a certain horizontal inner support have interference influence, the horizontal inner support is supported, and then the horizontal inner support is cut, dismantled, hoisted and transported out. The method has the beneficial effects that the safety risks of foundation pit collapse and the like caused by support replacement when deep foundation pit backfilling is not in place are avoided; the influence on the foundation pit and the structure when the inner support is dismantled is reduced, and the stability of the foundation pit and the structure is improved; the foundation pit cannot be backfilled in time due to various factors, an inner support influencing a structural system cannot be dismantled, part of structures cannot be constructed, and the construction period of related aspects can be shortened through the scheme.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of deep foundation pit construction operation, and particularly relates to a deep foundation pit horizontal inner support dismantling and support replacing method. BACKGROUND

[0002] With the rapid development of the construction industry in China, the construction scale is continuously expanded, and the urbanization process is continuously promoted, thereby the demand for infrastructure and public facilities is increasingly growing in China. However, the land resource is fixed, which promotes the construction to develop towards the underground and high altitude, and the newly-built projects have the characteristics of many basement floors, many adjacent existing building basement floors, many adjacent urban roads, and many adjacent municipal facilities. The deep foundation pit of the newly-built project cannot meet the traditional anchor cable tie support system, and needs to adopt the form of horizontal inner support combined with vertical support piles, and the phenomenon that the horizontal inner support affects the construction of the basement structure due to the land shortage occurs. At this time, the horizontal inner support needs to be dismantled. However, the limitation of some working conditions leads to that the deep foundation pit cannot be constructed according to the conventional "backfilling and replacing support" process, and the deformation control of the foundation pit during dismantling is a very big technical difficulty and "headache problem". SUMMARY

[0003] The application aims to provide a deep foundation pit horizontal inner support dismantling and support replacing method, and solve the problem of support replacing during the dismantling of the existing deep foundation pit horizontal inner support.

[0004] The application aims to achieve the above-mentioned purpose through the following technical scheme. A deep foundation pit horizontal inner support dismantling and support replacing method comprises the following steps. Step S1, planning and design according to the dismantling and support replacing; Step S2, a bottom layer support replacing plate is made between the raft foundation floor and the support pile through the support replacing template support; Step S3, a structure template support is erected on the lower floor, a structure floor and a structure outer wall plate of the layer are made through the structure template support, a support replacing template support is erected on the lower support replacing plate, and a top support replacing plate is made between the support pile and the structure outer wall plate of the layer through the support replacing template support; Step S4, the step S3 is repeated until the building structure of a certain layer and a certain horizontal inner support exist interference influence, the inner support temporary support is erected on the lower floor and the lower support replacing plate in advance before the structure template support is erected, the horizontal inner support is supported through the inner support temporary support, then the horizontal inner support is cut and dismantled and hoisted out; Step S5, the step S3 is repeated until the building structure of the negative one layer is made.

[0005] Further, the step S1, the position, size, concrete grade and reinforcement mode of the support replacing plate are planned and designed.

[0006] Further, the step S2 adopts the bottom layer replacement support formwork, the bottom layer replacement support formwork includes the opposite pull bolt, the opposite side formwork and the inclined support rod, the raft foundation floor, the support pile and the opposite side formwork jointly form the bottom layer replacement support pouring space, the opposite side formwork between being equipped with the opposite pull bolt, the outside of the opposite side formwork is equipped with the inclined support rod on the ground.

[0007] Further, the step S2, the bottom layer replacement support plate is no reinforcement concrete pouring.

[0008] Further, the step S3 adopts the top cross replacement support formwork, the top cross replacement support formwork includes the opposite pull bolt, the opposite side formwork, the inclined support rod, the transition support, the longitudinal main beam, the transverse secondary beam, the bottom formwork and the support steel pipe, the support pile, the structure outer wall plate, the bottom formwork and the opposite side formwork jointly form the top cross replacement support pouring space, the opposite side formwork between being equipped with the opposite pull bolt, the outside of the opposite side formwork is equipped with the inclined support rod on the support steel pipe, the bottom formwork is arranged on the transverse secondary beam, the transverse secondary beam is arranged on the longitudinal main beam, and the longitudinal main beam is arranged on the support steel pipe through the transition support.

[0009] Further, the step S3, the top cross replacement support plate is reinforced concrete pouring, the reinforcement in the top cross replacement support plate includes the transverse steel bar, the longitudinal steel bar and the inclined pull hanging steel bar, the two ends of the longitudinal steel bar are implanted in the support pile and the structure outer wall plate, and the upper end of the inclined pull hanging steel bar is implanted in the support pile.

[0010] Further, the step S3, the transverse steel bar and the longitudinal steel bar adopt double-layer arrangement.

[0011] Further, the step S3, when the steel bar is implanted, the steel bar is smeared with waterproof glue and the mouth is wrapped with waterproof oil paste; after the steel bar lapping and binding are finished, the concrete pouring is immediately carried out, and early strength agent is added in the concrete.

[0012] Further, the step S3 includes S301; S301, the negative three layer structure floor and the negative three layer structure outer wall plate are constructed on the raft foundation floor through the negative three layer structure formwork support, and the negative two layer top cross replacement support plate is constructed on the bottom layer replacement support plate through the negative two layer replacement support formwork support. Further, the step S4 includes S401 and S402; S401, the second inner support is supported on the negative three layer structure floor and the negative three layer top cross replacement support plate through the second inner support support, then the second inner support is cut off and removed and is hoisted and transported out; the negative two layer structure floor and the negative two layer structure outer wall plate are constructed on the negative three layer structure floor through the negative two layer structure formwork support, and the negative two layer top cross replacement support plate is constructed on the negative three layer top cross replacement support plate through the negative two layer replacement support formwork support. S402, the first internal support is supported by the first internal support bracket on the second basement floor slab and the top span of the second basement floor, and then the first internal support is cut, dismantled and hoisted out; the first basement floor slab and the first basement exterior wall panel are constructed on the second basement floor slab using the first basement floor formwork bracket.

[0013] Furthermore, in step S5, after the strength of the building structure on the basement level meets the standard, the steel columns are cut and dismantled.

[0014] The beneficial effects of this application are: 1. It avoids the safety risks of foundation pit collapse caused by replacement of supports when backfilling of deep foundation pits is inadequate.

[0015] 2. It reduced the impact of removing the internal supports on the foundation pit and structure, and improved the stability of the foundation pit and structure.

[0016] 3. Due to various factors, the foundation pit cannot be backfilled in time, and the internal supports of the structural system cannot be removed, resulting in the inability to construct some structures. This solution can shorten the construction period in related aspects.

[0017] 4. Only replacement support plates need to be installed at the locations where internal supports are removed, eliminating the need for large-scale backfilling and improving the efficiency of internal support removal and structural construction.

[0018] 5. It reduces the risk of paying penalties for breach of contract due to delays in construction.

[0019] The aforementioned main solution and its various further alternatives can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application; furthermore, the (non-conflicting alternatives) can also be freely combined with each other and with other alternatives. Those skilled in the art, after understanding the solution of this application, will realize from the prior art and common general knowledge that there are many combinations, all of which are technical solutions to be protected by this application, and will not be exhaustively listed here. Attached Figure Description

[0020] Figure 1 This is a structural plan view showing the positional relationships of this application.

[0021] Figure 2 This is a structural cross-sectional view showing the positional relationship of this application.

[0022] Figure 3 This is a flowchart illustrating the process of this application.

[0023] Figure 4 This is a structural schematic diagram of the bottom support template bracket of this application.

[0024] Figure 5 This is a structural diagram of the lowest level building structure and the replacement support in this application.

[0025] Figure 6 This is a structural schematic diagram of the lowest layer of the replacement support template in this application.

[0026] Figure 7 This is a schematic diagram of the reinforcement structure of the top span replacement slab in this application.

[0027] Figure 8 This is a schematic diagram of the removal of the first horizontal internal support in this application.

[0028] Figure 9 This is a schematic diagram of the removal of the last horizontal internal support in this application.

[0029] Figure 10 This is a structural diagram of the basement building structure of this application.

[0030] In the diagram: 1-Raft foundation slab, 2-Support piles, 3-Bottom floor replacement slab, 4-Structural formwork support, 5-Structural floor slab, 6-Structural exterior wall panel, 7-Replacement formwork support, 8-Top span replacement slab, 9-Internal support temporary support, 10-Horizontal internal support, 11-Steel column, 12-Cap beam, 13-Concrete retaining wall; 401-Basement 3rd floor structural formwork support, 402-Basement 2nd floor structural formwork support, 403-Basement 1st floor structural formwork support, 501-Basement 3rd floor structural slab, 502-Basement 2nd floor structural slab, 503-Basement 1st floor structural slab, 601-Basement 3rd floor structural exterior wall panel, 602-Basement 2nd floor structural exterior wall panel, 603-Basement 1st floor structural... Exterior wall panels, 701-Basement 3rd floor replacement formwork support, 702-Basement 2nd floor replacement formwork support, 703-Bottom floor replacement formwork support, 704-Tie bolts, 705-Opposite side formwork, 706-Diagonal struts, 707-Transition supports, 708-Longitudinal main beams, 709-Transverse secondary beams, 7010-Bottom formwork, 7011-Steel pipes for supports, 801-Basement 3rd floor top span replacement slab, 802-Basement 2nd floor top span replacement slab, 803-Transverse reinforcement, 804-Longitudinal reinforcement, 805-Diagonal tie rods, 901-Second inner support support, 902-First inner support support, 1001-Second inner support, 1002-First inner support Detailed Implementation The following non-limiting embodiments are used to illustrate this application.

[0031] This application applies to deep foundation pit design projects with three or two layers of horizontal internal bracing, where the deep foundation pit is adjacent to areas where anchor cables cannot be installed (such as cultural relic protection areas, existing buildings, etc.). These foundation pits typically use two layers of horizontal internal bracing plus pile foundations for support. This can lead to conflicts between the horizontal internal bracing and the basement structure, making basement construction impossible. Simultaneously, the working area outside the deep foundation pit is narrow, preventing timely backfilling. The planar and spatial relationship between the horizontal internal bracing and the basement structure is referenced. Figure 1 and Figure 2As shown, the horizontal internal support needs to be cut and removed.

[0032] Example 1 refer to Figures 1-10 As shown, a method for removing and replacing horizontal internal supports in a deep foundation pit includes the following steps: Step S1, planning and designing according to the removal and replacement, specifically planning and designing the location, size, concrete grade, and reinforcement method of the replacement support plate. The raft foundation slab 1 and the support piles 2 are already constructed structures. The top of the support piles 2 is formed as a whole by the capping beam 12. A concrete retaining wall 13 is provided on the upper part of the capping beam 12 to prevent debris from falling into the gap to be backfilled.

[0033] Step S2: The bottom support plate 3 is constructed between the raft foundation slab 1 and the support piles 2 using the support plate formwork support 7. The bottom support plate 3 is made of plain concrete without reinforcement, which can save the amount of steel reinforcement. The concrete is poured according to the design grade and size. The upper floor structure is constructed when the bottom support plate 3 reaches the design strength.

[0034] The replacement formwork support 7 used is the bottom-level replacement formwork support 703, which includes tie bolts 704, side formwork 705, and diagonal struts 706. The side formwork 705 is made of 15mm thick film-coated plywood, the tie bolts 704 are M12 tie rods, and the diagonal struts 706 are supported by φ48.3×3.6mm steel pipes.

[0035] The raft foundation slab 1, the support piles 2, and the opposite side formwork 705 together form the bottom support pouring space. Tie bolts 704 are installed between the opposite side formwork 705, and diagonal bracing rods 706 located on the ground are installed on the outer side of the opposite side formwork 705 to ensure that the opposite side formwork 705 enclosure is stable and does not deform or bulge.

[0036] Step S3: Erect a structural formwork support 4 on the lower floor slab, and construct the structural floor slab 5 and structural exterior wall panel 6 of this floor using the structural formwork support 4, curing the concrete until it reaches the design strength. Erect a replacement support formwork support 7 on the lower replacement support slab, and construct a top-and-bottom replacement support plate 8 between the support pile 2 and the structural exterior wall panel 6 of this floor using the replacement support formwork support 7.

[0037] The replacement formwork support 7 used is the top span replacement formwork support. The top span replacement formwork support includes tie bolts 704, side formwork 705, diagonal struts 706, transition support 707, longitudinal main beam 708, transverse secondary beam 709, bottom formwork 7010 and support steel pipe 7011. The longitudinal main beam 708 is a steel pipe, and the transverse secondary beam 709 is a timber. Other specifications and parameters are the same as above.

[0038] The support piles 2, the structural outer wall panels 6, the bottom formwork 7010, and the opposite side formwork 705 together form the top span replacement and pouring space. Tie bolts 704 are provided between the opposite side formworks 705, and diagonal bracing rods 706 located on the support steel pipe 7011 are provided on the outside of the opposite side formworks 705 to ensure that the opposite side formworks 705 are stable and do not deform or bulge.

[0039] The bottom formwork 7010 is set on several transverse secondary beams 709, which are set on at least two longitudinal main beams 708. The longitudinal main beams 708 are set on the support steel pipes 7011 through several transition support members 707. The transition support members 707 adopt a T-shaped structure, with their lower ends inserted into the support steel pipes 7011 and their upper ends forming U-shaped supports for the longitudinal main beams 708.

[0040] The top support plate 8 is made of reinforced plain concrete. The reinforcement in the top support plate 8 includes transverse steel bars 803, longitudinal steel bars 804, and diagonal tie bars 805. The transverse steel bars 803 and longitudinal steel bars 804 are arranged in a double layer. The two ends of the longitudinal steel bars 804 are embedded in the support piles 2 and the outer wall panel 6 of the structure, and the upper end of the diagonal tie bars 805 is embedded in the support piles 2.

[0041] During rebar installation, waterproof adhesive is applied to the rebars, and waterproof sealant is wrapped around the edges to improve waterproofing during the installation process. Concrete is poured immediately after the rebar lap splices are completed, with an early-strength agent added to the concrete to ensure construction safety. The next floor is constructed only after the replacement support plate has reached the design strength.

[0042] Step S4: Repeat step S3 until the building structure of a certain floor interferes with a certain horizontal internal support 10. Before erecting the structural formwork support 4, erect temporary internal support supports 9 on the lower floor slab and the lower replacement support slab. These temporary supports 9 will support the horizontal internal support 10. Then, the horizontal internal support 10 will be cut, dismantled, and hoisted out. During cutting, the hoisting equipment will be fixed to the horizontal internal support 10 beforehand to improve the safety factor of the construction. After removing the internal support, repeat step 3 to construct the building structure and replacement support slab.

[0043] Step S5: Repeat step S3 until the construction of the basement building structure is completed and then stop construction. Once the strength of the basement building structure meets the standard, that is, when it reaches 75% of the design strength, the steel column 11 is cut and removed.

[0044] Example 2 refer to Figures 1-9 As shown, for reference Figures 1-9 Figures 1-9 As shown, a method for removing and replacing horizontal internal supports in deep foundation pits is a refinement based on Example 1.

[0045] Step S3 includes S301. In S301, the third-floor structural slab 501 and the third-floor structural exterior wall panel 601 are constructed on the raft foundation slab 1 using the third-floor structural formwork support 401, and the top span replacement support slab 801 of the third floor is constructed on the bottom replacement support slab 3 using the third-floor replacement support formwork support 701.

[0046] Step S4 includes S401 and S402. In S401, the second inner support 1001 is supported by the second inner support bracket 901 on the third basement floor slab 501 and the top span support plate 801 of the third basement floor. Then, the second inner support 1001 is cut, dismantled, and hoisted out.

[0047] On the third basement floor slab 501, the second basement floor slab 502 and the second basement exterior wall panel 602 are constructed using the second basement floor formwork support 402. On the top span replacement support slab 801 of the third basement floor, the first basement floor slab 503 and the first basement exterior wall panel 603 are constructed using the second basement floor replacement support formwork support 702.

[0048] The foregoing basic examples and their further alternative examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed in this application. In the scheme of this application, each alternative example can be arbitrarily combined with any other basic example and alternative example.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for deep foundation pit horizontal inner support dismantling and support replacement, characterized in that, It comprises the following steps: Step S1, planning and designing according to the demolition and replacement of supports; Step S2, making a bottom replacement support plate (3) between the raft foundation floor (1) and the support pile (2) through the replacement support formwork (7); Step S3, supporting a structural formwork (4) on the lower floor, making the structural floor (5) and the structural outer wall plate (6) of the layer through the structural formwork (4), supporting the replacement support formwork (7) on the lower replacement support plate, and making a top replacement support plate (8) between the support pile (2) and the structural outer wall plate (6) of the layer through the replacement support formwork (7); Step S4, repeating step S3, if the building structure of a certain layer and a certain horizontal internal support (10) interfere with each other, supporting the internal support temporary support (9) on the lower floor and the lower replacement support plate in advance before supporting the structural formwork (4), supporting the internal support (10) through the internal support temporary support (9), then cutting and removing the internal support (10) and hoisting it out; Step S5, repeating step S3, stopping construction after the building structure of the negative layer is completed.

2. The method of removing and replacing horizontal inner supports of a deep foundation pit according to claim 1, wherein: The step S1 plans and designs the position, size, concrete grade, and reinforcement method of the replacement support plate.

3. The method of removing and replacing horizontal inner supports of a deep foundation pit according to claim 1, wherein: The replacement support formwork (7) used in step S2 is a bottom replacement support formwork (703), which comprises a tension bolt (704), opposite side formworks (705), and an inclined support rod (706). The raft foundation floor (1), the support pile (2), and the opposite side formworks (705) jointly form a bottom replacement support pouring space, the opposite side formworks (705) are provided with the tension bolt (704) therebetween, and the outer sides of the opposite side formworks (705) are provided with the inclined support rod (706) on the ground.

4. The method of removing and replacing horizontal inner supports of a deep foundation pit according to claim 1 or 3, characterized in that: The bottom replacement support plate (3) in step S2 is made of non-reinforced concrete.

5. The method of removing and replacing horizontal inner supports of a deep excavation according to claim 1, wherein: The replacement support formwork (7) used in step S3 is a top replacement support formwork, which comprises a tension bolt (704), opposite side formworks (705), an inclined support rod (706), a transition support (707), a longitudinal main beam (708), a transverse secondary beam (709), a bottom formwork (7010), and a support steel pipe (7011). The support pile (2), the structural outer wall plate (6), the bottom formwork (7010), and the opposite side formworks (705) jointly form a top replacement support pouring space, the opposite side formworks (705) are provided with the tension bolt (704) therebetween, the outer sides of the opposite side formworks (705) are provided with the inclined support rod (706) on the support steel pipe (7011), the bottom formwork (7010) is arranged on the transverse secondary beam (709), the transverse secondary beam (709) is arranged on the longitudinal main beam (708), and the longitudinal main beam (708) is arranged on the support steel pipe (7011) through the transition support (707).

6. The method of removing and replacing lateral bracing in a deep excavation according to claim 1, wherein: The step S3, the top cross support plate (8) is reinforced concrete pouring, the reinforcement in the top cross support plate (8) includes transverse steel bars (803), longitudinal steel bars (804) and inclined pull hanging steel bars (805), the two ends of the longitudinal steel bars (804) are implanted in the supporting pile (2) and the structure outer wall plate (6), and the upper end of the inclined pull hanging steel bars (805) is implanted in the supporting pile (2).

7. The method of removing and replacing horizontal inner supports of a deep foundation pit according to claim 6, wherein: The step S3, the transverse steel bars (803) and the longitudinal steel bars (804) are arranged in double layers.

8. The method of removing and replacing horizontal inner supports of a deep foundation pit according to claim 6, wherein: The step S3, when the steel bars are planted, the steel bars are smeared with waterproof glue, and the mouth is wrapped with waterproof ointment; after the steel bar lapping and binding are completed, the concrete pouring is immediately carried out, and early strength agent is added in the concrete.

9. The method of removing and replacing lateral bracing of a deep excavation according to claim 1, wherein: The step S3 includes S301; S301, the negative three-layer structure floor (501) and the negative three-layer structure outer wall plate (601) are constructed on the raft foundation floor (1) through the negative three-layer structure formwork support (401), and the negative three-layer top cross support plate (801) is constructed on the bottom cross support plate (3) through the negative three-layer cross support formwork support (701). The step S4 includes S401 and S402; S401, the second inner support (1001) is supported on the negative three-layer structure floor (501) and the negative three-layer top cross support plate (801) through the second inner support support (901), then the second inner support (1001) is cut and removed and hoisted and transported out; the negative two-layer structure floor (502) and the negative two-layer structure outer wall plate (602) are constructed on the negative three-layer structure floor (501) through the negative two-layer structure formwork support (402), and the negative two-layer top cross support plate (802) is constructed on the negative three-layer top cross support plate (801) through the negative two-layer cross support formwork support (702); S402, the first inner support (1002) is supported on the negative two-layer structure floor (502) and the negative two-layer top cross support plate (802) through the first inner support support (902), then the first inner support (1002) is cut and removed and hoisted and transported out; the negative one-layer structure floor (503) and the negative one-layer structure outer wall plate (603) are constructed on the negative two-layer structure floor (502) through the negative one-layer structure formwork support (403).

10. The method of removing and replacing lateral bracing in a deep excavation according to claim 1, wherein: The step S5, after the strength of the negative one-layer building structure reaches the standard, the steel column (11) is cut and removed.

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