SWM method combined with pile support structure for soft soil deep foundation pit and construction method thereof

Abstract

The present application relates to the technical field of deep foundation pit support engineering, in particular to a SWM method pit wall combined reinforcement pile support structure of a soft soil deep foundation pit and a construction method thereof, comprising two groups of vertical H-shaped steels arranged vertically along the side walls of the foundation pit, and horizontal H-shaped steels distributed vertically and connected between the two groups of vertical H-shaped steels; a plurality of vertically distributed steel members are arranged between the two groups of vertical H-shaped steels, the upper and lower ends of the steel members are provided with end sealing plates, and the front surface is provided with side sealing plates, the end sealing plates and the side sealing plates are in sealing cooperation with the steel members, so that a closed cavity with an internal hollow is formed in the steel members; a plurality of horizontal reinforcing ribs and inclined reinforcing ribs are arranged on the back surface of the steel members and between the two vertical H-shaped steels, the horizontal reinforcing ribs and the inclined reinforcing ribs are arranged along the length direction of the vertical H-shaped steels, the present application effectively improves the overall rigidity and stability of the soft soil deep foundation pit support structure, realizes the integrated and collaborative work of the anchor cable and the support wall, and can more effectively control the deformation of the soft soil deep foundation pit.

Description

Technical Field

[0001] This invention relates to the field of deep foundation pit support engineering technology, specifically to the SWM method for reinforcing pile support structure of pit wall in soft soil deep foundation pits and its construction method. Background Technology

[0002] Deep foundation pit projects in soft soil areas are prone to risks such as foundation pit deformation, instability, and leakage during excavation due to the characteristics of the soil itself, such as low strength, high compressibility, and poor permeability. These risks pose a serious threat to the safety of the project itself and the surrounding environment. Therefore, it is necessary to develop a safe and reliable support structure that also has good soil retention and water-stopping performance.

[0003] The SWM method is a typical foundation pit support technology. It forms a composite retaining and water-stopping structure by inserting H-beams into a cement-soil mixing wall. It has been widely used under general geological conditions. However, in deep foundation pits in soft soil with large depths, complex environments, and high requirements for deformation control, the traditional SWM method support structure still has the following limitations: First, its support stiffness mainly depends on the discretely inserted H-beams. The cement-soil mainly plays a role in water stopping and seepage prevention, and its contribution to the overall stiffness is limited. In deep soft soil, it is often difficult to meet the strict deformation control requirements. Second, when prestressed anchors are required to provide horizontal constraints, the anchors are usually set independently of the steel-cement-soil wall. The connection and collaborative working mechanism between the two is not tight enough, and the anchor tension cannot be effectively transferred to the entire support wall, affecting the overall stiffness and effective deformation control.

[0004] To address these issues, we provide the SWM method for reinforcing pile support structures for deep foundation pits in soft soil, along with its construction method. Summary of the Invention

[0005] The purpose of this invention is to provide a combined pile support structure for pit walls reinforced by the SWM method for deep foundation pits in soft soil and its construction method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The SWM method for reinforcing the walls of deep foundation pits in soft soil includes two sets of vertical H-beams set vertically along the sidewalls of the foundation pit, and horizontal H-beams distributed vertically at intervals and connected between the two vertical H-beams.

[0008] Multiple vertically distributed steel components are arranged between the two vertical H-beams. Each steel component has an end sealing plate at both the top and bottom and a side sealing plate on the front. The end sealing plates and side sealing plates work together to seal the steel component, forming a closed cavity with a hollow interior.

[0009] On the back of the steel member and between the two vertical H-beams, there are a number of horizontal and diagonal reinforcing ribs installed along the length of the vertical H-beams.

[0010] A grouting pipe is provided on the horizontal H-beam corresponding to the position of each steel component, and the grouting pipe is connected to the inside of the steel component.

[0011] An anchor cable is movably inserted into the grouting pipe, and the anchor cable also passes through the steel component. Concrete can be injected into the steel component through the grouting pipe, so that the steel component forms an internally reinforced rigid concrete column.

[0012] The SWM method for reinforcing pile support structure of deep foundation pits in soft soil, as described above, consists of multiple horizontal reinforcing bars that are evenly distributed along the length of the vertical H-beams.

[0013] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: multiple inclined reinforcing bars are distributed at equal intervals along the length of the vertical H-beam, and the inclined reinforcing bars are set at an incline.

[0014] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: multiple vent holes are provided on the side sealing plate at equal intervals along the length of the side sealing plate.

[0015] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: multiple equally spaced connecting rods are installed on the vertical H-beam along its length, and connecting steel bars are installed on the connecting rods.

[0016] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: the two ends of the vertical H-beam are respectively equipped with ear plates.

[0017] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: the grouting pipe has grouting holes with an inner diameter that matches the outer diameter of the anchor cable. The anchor cable is movably inserted into the grouting hole, and concrete can be injected into the grouting pipe through the grouting hole.

[0018] The SWM method for reinforcing pile support structure of deep foundation pit in soft soil as described above: the end sealing plate has a through hole with an inner diameter that matches the outer diameter of the anchor cable, and the anchor cable is movably inserted into the through hole.

[0019] The construction method of the SWM method for reinforcing pile support structure of pit wall in soft soil deep foundation pits includes the following steps:

[0020] S1. Measure and set out the design location of the foundation pit, and construct cement-soil mixing piles along the support boundary to form a water-stop curtain and retaining wall for the foundation pit. Before the cement-soil initially sets, insert vertical H-beams into the mixing piles to the designed depth.

[0021] S2. After the cement soil reaches a certain strength, excavate the soil to below the design elevation of the first horizontal H-beam. Install the first horizontal H-beam between the exposed vertical H-beams and reliably connect them. Then, at the design position between the two vertical H-beams, install the second horizontal H-beam and steel components. Seal and weld the upper and lower end sealing plates and the front side sealing plates of the steel components to form a closed cavity. At the same time, install horizontal reinforcing ribs and diagonal reinforcing ribs between the two vertical H-beams on the back of the steel components.

[0022] S3, through the grouting pipe on the first horizontal H-beam and the perforation at the end of the steel component, the anchor cable is passed from the outside of the foundation pit, through the cavity of the steel component, and driven into the soil at the bottom of the foundation pit to the predetermined anchoring depth. The anchor cable is tensioned and prestressed, and then locked on the horizontal H-beam. Then concrete is poured into the cavity of the steel component through the grouting hole to form a stiffened concrete column.

[0023] S4. After the strength of the first layer of support structure meets the requirements, excavate downwards to the design elevation of the next horizontal H-beam. Repeat steps S1 to S3, and install the horizontal H-beam, steel components, horizontal reinforcing bars, diagonal reinforcing bars and anchor cables for this layer. Repeat this process, excavating and supporting layer by layer downwards until the design bottom elevation of the foundation pit is reached.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The present invention sets multiple horizontal reinforcing bars, diagonal reinforcing bars and steel components between the vertical H-beams on both sides, and fills the steel components with concrete to form a stiff concrete column, which together with the vertical H-beams, horizontal H-beams and cement-soil walls constitutes a spatial composite force system to realize the support structure for the foundation pit wall. Among them, the horizontal reinforcing bars, diagonal reinforcing bars and steel components configured between the two vertical H-beams effectively improve the shear resistance of the components and effectively enhance the overall bending stiffness and spatial stability of the support structure against lateral earth pressure, thereby more effectively controlling the deformation of the soft soil deep foundation pit;

[0026] (2) The anchor cable of the present invention is inserted through the grouting pipe on the horizontal H-beam and passes through the closed cavity of the entire steel component. The cavity is formed by the sealing of the end sealing plate and the side sealing plate, which provides the installation channel and protection space for the anchor cable. Concrete is injected into the steel component through the grouting pipe, so that the anchor cable, steel component, horizontal reinforcing bar, diagonal reinforcing bar and concrete are consolidated into a whole. This structure allows the prestress applied by the anchor cable to be directly and uniformly diffused to the entire support wall structure through the steel component, which effectively improves the force transmission path and significantly improves the constraint efficiency of the anchor cable on the deformation of the wall. Attached Figure Description

[0027] Figure 1 This is a first-view overall structural schematic diagram of the SWM method for reinforcing pile support structure of deep foundation pit in soft soil.

[0028] Figure 2 This is a schematic diagram of the overall structure from a second perspective of the SWM method for reinforcing pile support structure of deep foundation pits in soft soil.

[0029] Figure 3 for Figure 1 A schematic diagram of the decomposed part of the structure.

[0030] Figure 4 for Figure 1 A schematic diagram of the decomposed part of the structure.

[0031] Figure 5 for Figure 4 A schematic diagram of the decomposed part of the structure.

[0032] Figure 6 for Figure 5 A schematic diagram of the decomposed part of the structure.

[0033] Figure 7 for Figure 6 A schematic diagram of the decomposed part of the structure.

[0034] In the diagram: 1. Vertical H-beam; 2. Horizontal H-beam; 3. Horizontal reinforcing bar; 4. Diagonal reinforcing bar; 5. Steel component; 6. Side sealing plate; 7. Grouting pipe; 8. Anchor cable; 9. Vent hole; 10. Connecting rod; 11. Ear plate; 12. End sealing plate; 13. Grouting hole; 14. Perforation; 15. Connecting reinforcing bar. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0036] Please see Figures 1-7As an embodiment of the present invention, the SWM method for reinforcing pile support structure of deep foundation pit in soft soil includes two sets of vertical H-beams 1 arranged vertically along the side wall of the foundation pit, and horizontal H-beams 2 distributed vertically at intervals and connected between the two vertical H-beams 1.

[0037] Multiple vertically distributed steel components 5 are arranged between the two vertical H-beams 1. The upper and lower ends of the steel components 5 are provided with end sealing plates 12, and the front is provided with side sealing plates 6. The end sealing plates 12 and the side sealing plates 6 work together to seal the steel components 5, so that the steel components 5 form a closed cavity with a hollow interior.

[0038] On the back of the steel component 5 and between the two vertical H-beams 1, there are multiple horizontal reinforcing ribs 3 and diagonal reinforcing ribs 4 installed along the length of the vertical H-beams 1.

[0039] A grouting pipe 7 is installed on the horizontal H-beam 2 at the position corresponding to each steel component 5, and the grouting pipe 7 is connected to the inside of the steel component 5;

[0040] Anchor cables 8 are movably inserted into the grouting pipe 7. The anchor cables 8 also pass through the steel component 5. Concrete can be injected into the steel component 5 through the grouting pipe 7, so that the steel component 5 forms an internally reinforced rigid concrete column.

[0041] In this embodiment, during excavation, vertical H-beams 1 and horizontal H-beams 2 spaced vertically are placed into the pit. After concrete is poured, they together form the basic pit wall support frame. Multiple vertically distributed steel members 5 are installed between the two vertical H-beams 1, their interiors sealed by end-sealing plates 12 and side-sealing plates 6 to form hollow cavities. When concrete is injected into the steel members 5 through grouting pipes 7 corresponding to those on the horizontal H-beams 2, the steel members 5 transform into dense, structurally reinforced concrete columns, thereby significantly improving the support structure at that location. The vertical bearing capacity and bending stiffness are enhanced. Meanwhile, the anchor cable 8 is inserted from the grouting pipe 7 and extends into the bottom of the foundation pit after passing through the entire cavity of the steel component 5. The multiple horizontal reinforcing bars 3 and diagonal reinforcing bars 4 set on the back of the steel component 5 further enhance the shear resistance of the entire support structure. During the excavation of the foundation pit, the lateral earth pressure is transmitted through the cement-soil wall to the spatial frame composed of the vertical H-beam 1, the horizontal H-beam 2 and the reinforced steel component 5, and is balanced by the anchor cable 8 that passes through the steel component 5, thereby jointly achieving stable support for the sidewall of the deep foundation pit.

[0042] As a further embodiment of the present invention, multiple horizontal reinforcing ribs 3 are distributed at equal intervals along the length direction of the vertical H-beam 1.

[0043] In this embodiment, the equally spaced horizontal stiffeners 3 can uniformly transfer and distribute the load, enhance the overall connection between the steel member 5 and the vertical H-beams 1 on both sides, and improve the overall stability and deformation resistance of the support structure in the vertical plane.

[0044] As a further embodiment of the present invention, a plurality of diagonal reinforcing ribs 4 are distributed at equal intervals along the length direction of the vertical H-beam 1, and the diagonal reinforcing ribs 4 are inclined.

[0045] In this embodiment, the inclined diagonal reinforcing ribs 4 and the horizontally arranged horizontal reinforcing ribs 3 work together to form a stable truss-type support system on the back of the steel component 5, which effectively improves the ability of the support structure in this area to resist shear deformation and local bending.

[0046] As a further embodiment of the present invention, the side sealing plate 6 is provided with a plurality of exhaust holes 9 evenly distributed along the length direction of the side sealing plate 6.

[0047] In this embodiment, the vent hole 9 opened on the side sealing plate 6 can effectively expel the air in the cavity when concrete is poured into the steel component 5 through the grouting pipe 7, ensuring that the concrete is filled densely, thereby guaranteeing the quality and strength of the final reinforced concrete column.

[0048] As a further embodiment of the present invention, a plurality of equally spaced connecting rods 10 are installed on the vertical H-beam 1 along its length direction, and connecting reinforcing bars 15 are installed on the connecting rods 10.

[0049] In this embodiment, the connecting rod 10 and the connecting steel bar 15 form a connecting node, which facilitates a rapid and firm rigid connection with the concrete level inside the foundation pit, thereby forming an internal support system that coordinates spatial forces and further enhances the overall constraint capability against foundation pit deformation.

[0050] As a further embodiment of the present invention, ear plates 11 are respectively installed at both ends of the vertical H-beam 1.

[0051] In this embodiment, ear plates 11 are installed at both ends of the vertical H-beam 1 to facilitate the prefabricated connection of the vertical H-beam 1 with adjacent support components or connecting structures in the horizontal direction, thereby enhancing the construction convenience and integrity of the node structure.

[0052] As a further embodiment of the present invention, the grouting pipe 7 is provided with a grouting hole 13 whose inner diameter is adapted to the outer diameter of the anchor cable 8. The anchor cable 8 is movably inserted into the grouting hole 13, and concrete can be injected into the grouting pipe 7 through the grouting hole 13.

[0053] In this embodiment, the grouting hole 13 provides guidance and a channel for the insertion of the anchor cable 8, ensuring the accurate installation position of the anchor cable 8. On the other hand, it also serves as a grouting hole for injecting concrete into the steel component 5.

[0054] As a further embodiment of the present invention, the end cap plate 12 is provided with a through hole 14 whose inner diameter is adapted to the outer diameter of the anchor cable 8, and the anchor cable 8 is movably inserted into the through hole 14.

[0055] In this embodiment, the perforation 14 on the end cap plate 12 is concentrically corresponding to the grouting hole 13 on the grouting pipe 7, which together ensures that the anchor cable 8 can pass straight through the cavity of the entire steel component 5.

[0056] In use: First, vertically arranged vertical H-beams 1 and horizontally spaced H-beams 2 are placed in the foundation pit to form the main support frame. Then, vertical steel members 5 are installed between the vertical H-beams 1 on both sides. They are reinforced with the vertical H-beams 1 by horizontal reinforcing ribs 3 and diagonal reinforcing ribs 4 on the back, forming a spatial grid-like structural reinforcement system. During construction, cement soil is added to the foundation pit and mixed to form a water-stop wall. Then, the above-mentioned spatial grid-like reinforcement structure is installed. Subsequently, anchor cables 8 are passed through the grouting holes 13 on the grouting pipe 7, the internal cavity of the steel member 5, and the end sealing plate 12 in sequence. The steel member 5 is perforated 14 and anchored into the bottom of the foundation pit to stabilize the soil. Then, concrete is poured into the sealed cavity of the steel member 5 through the grouting pipe 7 and grouting hole 13 to form a high-rigidity structurally reinforced concrete column. Finally, prestress is applied to the anchor cable 8 and locked. Thus, the lateral soil pressure of the foundation pit is transmitted through the cement-soil wall to the composite spatial frame composed of vertical H-beams 1, horizontal H-beams 2 and structurally reinforced steel member 5, and balanced by the anchoring tension provided by the prestressed anchor cable 8, thereby forming a deep support structure, which together achieves effective control of the stability and deformation of the sidewall of the soft soil deep foundation pit.

[0057] The above embodiments are exemplary and not restrictive. Therefore, any technical solutions that can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention are included within the scope of the present invention.

Claims

1. A combined pile support structure for pit walls reinforced by the SWM method in deep foundation pits of soft soil, characterized in that, It includes two sets of vertical H-beams (1) set vertically along the side wall of the foundation pit, and horizontal H-beams (2) distributed vertically at intervals and connected between the two vertical H-beams (1); Multiple vertically distributed steel components (5) are arranged between the two vertical H-beams (1). The upper and lower ends of the steel components (5) are provided with end sealing plates (12), and the front is provided with side sealing plates (6). The end sealing plates (12) and the side sealing plates (6) work together to seal the steel components (5), so that the steel components (5) form a closed cavity with a hollow interior. On the back of the steel member (5) and between the two vertical H-beams (1), a plurality of horizontal reinforcing ribs (3) and diagonal reinforcing ribs (4) are provided along the length of the vertical H-beams (1). A grouting pipe (7) is provided on the horizontal H-beam (2) at the position corresponding to each steel component (5), and the grouting pipe (7) is connected to the inside of the steel component (5); An anchor cable (8) is movably inserted into the grouting pipe (7). The anchor cable (8) also passes through the steel component (5). Concrete can be injected into the steel component (5) through the grouting pipe (7) so that the steel component (5) forms an internally reinforced rigid concrete column.

2. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, Multiple horizontal reinforcing ribs (3) are distributed at equal intervals along the length of the vertical H-beam (1).

3. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, Multiple oblique reinforcing ribs (4) are distributed at equal intervals along the length direction of the vertical H-beam (1), and the oblique reinforcing ribs (4) are set at an angle.

4. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, The side sealing plate (6) has multiple exhaust holes (9) that are evenly distributed along the length of the side sealing plate (6).

5. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, Multiple equally spaced connecting rods (10) are installed on the vertical H-beam (1) along its length direction, and connecting steel bars (15) are installed on the connecting rods (10).

6. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, The vertical H-beam (1) is fitted with ear plates (11) at both ends.

7. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, The grouting pipe (7) has an grouting hole (13) with an inner diameter that matches the outer diameter of the anchor cable (8). The anchor cable (8) is movably inserted into the grouting hole (13), and concrete can be injected into the grouting pipe (7) through the grouting hole (13).

8. The SWM method for reinforcing pile support structure of deep foundation pits in soft soil according to claim 1, characterized in that, The end cap plate (12) has a through hole (14) with an inner diameter that matches the outer diameter of the anchor cable (8), and the anchor cable (8) is movably inserted into the through hole (14).

9. A construction method for a combined reinforced pile support structure for deep foundation pits in soft soil using the SWM method, based on any one of claims 1-8, characterized in that... Includes the following steps, S1, measure and set out the design location of the foundation pit, construct cement-soil mixing piles along the support boundary to form the water-stop curtain and retaining wall of the foundation pit, and insert the vertical H-beam (1) into the mixing pile to the design depth before the cement-soil initially sets. S2, after the cement soil reaches a certain strength, excavate the soil to below the design elevation of the first horizontal H-beam (2), install the first horizontal H-beam (2) between the exposed vertical H-beams (1) and reliably connect them. Then, at the design position between the two vertical H-beams (1), install the second horizontal H-beam (2) and steel components (5), and seal and weld the upper and lower end sealing plates (12) and the front side sealing plates (6) of the steel components (5) to form a closed cavity. At the same time, on the back of the steel components (5), install horizontal reinforcing ribs (3) and diagonal reinforcing ribs (4) between the two vertical H-beams (1). S3, through the grouting pipe (7) on the first horizontal H-beam (2) and the perforation (14) at the end of the steel component (5), the anchor cable (8) is passed through the outside of the foundation pit, through the cavity of the steel component (5), and driven into the bottom soil of the foundation pit to the predetermined anchoring depth. The anchor cable (8) is tensioned and prestressed, and then locked on the horizontal H-beam (2). Then concrete is poured into the cavity of the steel component (5) through the grouting hole (13) to form a stiffened concrete column. S4. After the strength of the first layer of support structure meets the requirements, excavate downwards to the design elevation of the next horizontal H-beam (2). Repeat steps S1 to S3, and install the horizontal H-beam (2), steel components (5), horizontal reinforcing bars (3), diagonal reinforcing bars (4) and anchor cables (8) of this layer. Repeat this process to excavate and support downwards layer by layer until the design bottom elevation of the foundation pit is reached.

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