A construction method for a self-stabilizing foundation pit support structure

Abstract

The application relates to a construction method of a self-stable foundation pit supporting structure, which comprises the following steps: 1) setting double-row supporting piles, and setting inclined braces in the pit on the top of the double-row supporting piles; 2) pouring a ring beam, a connecting beam and a pressing top plate on the top of the double-row supporting piles, and fixing the first inclined brace; 3) excavating downwards to the second inclined brace, and fixing the second inclined brace by constructing a concrete ring beam at the joint of the inclined brace of the outer supporting pile and the inner supporting pile; 4) continuously excavating downwards, and repeating the above steps until the base, and immediately pouring a reinforced cushion layer on the pit-facing side of the base to fix all the inclined braces; and 5) constructing a bottom plate basement structure, setting a water-stopping steel plate at the position where the inclined brace penetrates the bottom plate and the outer wall of the basement to prevent water leakage, and cutting off the steel pipe intruding into the outer wall of the basement after the basement is out of the ground and backfilled. The application can avoid the problems of the single-row supporting pile structure, such as weak overall rigidity of the single inclined brace, and can improve the overall rigidity and stability of the enclosure, and reduce the deformation of the foundation pit.

Description

Technical Field

[0001] This invention relates to a self-stabilizing foundation pit support structure, and more particularly to a construction method for a self-stabilizing foundation pit support structure. Background Technology

[0002] To excavate large-area foundation pits quickly, construction techniques such as diagonal bracing are currently used. However, these techniques are only suitable for shallow foundation pits. The difficulty in setting up multiple diagonal braces limits their application in large, deep foundation pits. Traditional internal bracing methods require the installation of numerous lattice columns and piles. The construction and removal of concrete supports consume a significant amount of construction time and do not align with the current green construction philosophy of low-carbon and environmental protection. Summary of the Invention

[0003] The present invention provides a construction method for a self-stabilizing foundation pit support structure. This method involves installing diagonal bracing at the top of the inner and outer rows of piles into the pit, excavating in layers, and pouring a concrete ring beam to fix the diagonal bracing at each layer, thereby forming a self-stabilizing foundation pit support structure with double rows of piles and multiple diagonal bracing.

[0004] To achieve the above objectives, the technical solution of the present invention is: a construction method for a self-stabilizing foundation pit support structure, the steps of which are as follows:

[0005] 1) Install double-row support piles, and drive diagonal bracing into the pit at the top of both rows of support piles;

[0006] 2) Pour the top ring beam, connecting beam and capping plate of the double-row pile support piles, and fix the first diagonal brace;

[0007] 3) Excavate downwards to the second diagonal brace. At the junction of the diagonal brace of the outer row of support piles and the inner row of piles, construct a concrete ring beam to fix the second diagonal brace.

[0008] 4) Continue excavating downwards, repeating the above steps to the foundation. Immediately pour a reinforced cushion layer on the pit-facing side of the foundation to fix all diagonal braces.

[0009] 5) Construct the basement structure with the foundation slab. Install water-stop steel plates at the points where the diagonal braces penetrate the foundation slab and the basement exterior walls to prevent water leakage. After the basement is above ground level and backfilled, cut off the steel pipes that have penetrated into the basement exterior walls.

[0010] Furthermore, the double-row support piles are cast-in-place piles or SMW method pile-slab support piles.

[0011] Furthermore, the inclined bracing at the top of the outer row of support piles needs to pass through the inner row of support piles. In the SMW method, the inserted H-beams need to be avoided, and the pile support needs to avoid the cast-in-place piles. Therefore, the net spacing between the cast-in-place piles of the inner row of support piles should be arranged in conjunction with the outer diameter of the steel pipe inclined bracing, and a certain construction error should be reserved.

[0012] Furthermore, a water-stop curtain is installed at the outermost row of support piles.

[0013] Furthermore, the number of diagonal braces is determined based on the excavation depth. Only one diagonal brace is installed in the inner row of piles as the first brace, while multiple diagonal braces are installed in the outer row of piles. The angles of the multiple diagonal braces need to be rotated to avoid conflicts.

[0014] Furthermore, once the foundation is excavated to the base, the risk of the foundation pit reaches its maximum. A reinforced concrete cushion layer with a certain thickness should be constructed quickly, with a cushion layer thickness of not less than 300mm. At the same time, all diagonal braces should be fixed within the construction area, and the extension should extend to the farthest diagonal brace and not less than 6m.

[0015] The beneficial effects of this invention are: by using the construction method of this invention, the problems of weak overall rigidity of single row support pile structure with single diagonal bracing can be avoided. At the same time, the use of double row piles can improve the overall rigidity and stability of the retaining structure and reduce the deformation of the foundation pit. Compared with traditional internal support, this support structure has the advantages of construction convenience and economy. It is much stronger than the traditional method in terms of technical feasibility, work efficiency and implementation effect. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of a self-stabilizing foundation pit support structure;

[0017] Figures 2-3 These are detailed drawings of the ring beams and connecting beams of a self-stabilizing foundation pit support structure.

[0018] Figure 4 This is a construction sequence diagram for a self-stabilizing foundation pit support structure. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] like Figures 1 to 4 As shown, a construction method for a self-stabilizing foundation pit support structure includes the following steps:

[0021] 1) Install double-row support piles 1 in the foundation pit, and drive diagonal bracing 2 into the pit from the top of the double-row support piles;

[0022] 2) Pour the top ring beam, connecting beam and capping plate 3 of the double row pile support pile 1, and fix the first diagonal brace 2;

[0023] 3) Excavate downwards to the second diagonal brace 2, that is, the junction of the outer row of support piles diagonal brace 2 and the inner row of piles, and construct a concrete ring beam 4 to fix the second diagonal brace 2.

[0024] 4) Continue excavating downwards, repeating the above steps to the foundation. Immediately pour a reinforced cushion layer on the pit-facing side of the foundation to fix all diagonal braces.

[0025] 5) For the construction of the basement structure, such as the foundation slab, water-stop steel plates are installed at the diagonal bracing 2 through the foundation slab and the basement exterior wall to prevent water leakage. After the basement is above ground and backfilled, the steel pipes that have penetrated into the basement exterior wall are cut off.

[0026] Double-row support piles 1 are installed. The support can be provided using cast-in-place piles or SMW method piles, etc. The water-stop curtain is set at the outermost row of support piles. Diagonal braces are driven into the pit from the top of both rows of support piles. The number of diagonal braces is determined according to the excavation depth. Only one diagonal brace 2 is driven into the inner row of piles as the first brace, while multiple diagonal braces 2 can be driven into the outer row of piles. The angle of the multiple diagonal braces needs to be rotated to avoid conflict.

[0027] The top ring beam, connecting beam, and capping plate of the double-row pile support are used to fix the first diagonal bracing. At this time, the diagonal bracing at the top of the outer row support is also fixed as a safety reserve.

[0028] The diagonal bracing at the top of the outer row of supports needs to pass through the inner row of supports. The SMW method needs to avoid the inserted H-beams, and the pile support needs to avoid the cast-in-place piles. Therefore, the net spacing between the cast-in-place piles in the inner row of piles should be arranged in conjunction with the outer diameter of the steel pipe diagonal bracing, and a certain construction error should be reserved.

[0029] Once the foundation is excavated to the base, the risk of the foundation pit reaches its maximum. At this point, the construction of the base slab is relatively slow. A reinforced concrete cushion layer with a certain thickness should be constructed quickly, with a cushion layer thickness of not less than 300mm. At the same time, all diagonal braces should be fixed within the construction area, and the extension should extend to the farthest diagonal brace and not less than 6m.

Claims

1. A construction method of a self-stabilizing foundation pit support structure, characterized by, The steps are: 1) Set double-row support piles, and set inclined braces in the pit on the top of the double-row support piles; 2) Pour the top beam, coupling beam and pressure top plate of the double-row pile support pile, and fix the first inclined brace; the double-row support pile uses cast-in-place pile or SMW method pile plate support pile; 3) Excavate downward to the second inclined brace, and fix the second inclined brace at the intersection of the inclined brace of the outer row support pile and the inner row pile by pouring the concrete coupling beam; the inclined brace on the top of the outer row support pile needs to pass through the inner row support pile, and the SMW method needs to avoid the H-shaped steel inserted, and the row pile support needs to avoid the cast-in-place pile, so the net distance of the cast-in-place pile of the inner row support pile should be arranged in combination with the size of the outer diameter of the steel pipe inclined brace, and a certain construction error is reserved; 4) Continue to excavate downward, repeat the above steps, and after excavating to the base, immediately pour the reinforced cushion layer on the base side facing the pit to fix all the inclined braces; 5) Construct the basement structure of the bottom plate, set the water stop steel plate at the position where the inclined brace penetrates the bottom plate and the outer wall of the basement to prevent water leakage, and cut off the steel pipe intruding into the outer wall of the basement after the basement is out of the ground and backfilled.

2. The construction method of a self-stabilizing foundation pit support structure according to claim 1, characterized by: A water stop curtain is arranged at the outermost row of support piles.

3. The construction method of a self-stabilizing foundation pit support structure according to claim 1, characterized by: The number of inclined braces is determined according to the excavation depth, and only one inclined brace is set on the inner row pile as the first brace, and multiple inclined braces are set on the outer row pile, and the angle of the multiple inclined braces needs to be rotated to avoid conflict.

4. The construction method of a self-stabilizing foundation pit support structure according to claim 1, characterized by: After excavating to the base, the risk of the foundation pit reaches the maximum, and a certain thickness of concrete reinforced cushion layer should be quickly constructed, the thickness of the cushion layer is not less than 300mm, at the same time, the construction range should fix all the inclined braces, and extend to the farthest inclined brace and not less than 6m.

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