Supporting method and system suitable for low-viscosity sand foundation pit

Abstract

The invention discloses a supporting method and system suitable for a low-viscosity sand foundation pit. The supporting method comprises the steps that S1, a supporting face is determined, and first steel sheet piles are inserted into the supporting face; s2, the original ground of the excavation side of the first steel sheet pile is excavated by a set depth, and an excavation side working face is formed; s3, a steel strand is installed on the working face of the excavation side, and the first end of the steel strand extends into a soil layer, with a certain depth, of the non-excavation side of the first steel sheet pile; s4, grouting is conducted in the soil layer on the peripheral side of the tail end of the first end of the steel strand to form a consolidation body, and the tail end of the first end of the steel strand is wrapped with the consolidation body; s5, after the consolidated body reaches the set strength, the second end of the steel strand is tensioned, and the second end of the steel strand is fixed to the excavation side face of the first steel sheet pile through an arranged tensioning structure; s6, the excavation side working face is excavated, and an excavation side design face is formed; and other subsequent working procedure construction is carried out on the excavation side design face. And larger anti-sliding force is provided for slope supporting, so that slope deformation is better resisted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building construction, in particular to a supporting method and system suitable for low-cohesion sandy soil foundation pit. BACKGROUND

[0002] The sandy soil foundation is widely distributed, and its soil layer has poor structural property and high permeability, which brings significant challenges to foundation pit engineering. On the one hand, the sandy soil lacks cohesion and has poor self-supporting property, and is prone to collapse. On the other hand, the high permeability of the sandy soil leads to prominent seepage problems of underground water, and is prone to gushing, quicksand and even seepage failure, which seriously threatens the stability of the foundation pit. As a traditional supporting form, the first Larsen steel sheet pile has obvious advantages in shallow foundation pit, trench and temporary engineering, but has certain limitations in the application of deep sandy soil foundation pit. The single-row first steel sheet pile has insufficient stiffness and is difficult to effectively control the lateral deformation of the deep foundation pit. The traditional reinforcement measures such as anchor rod are prone to borehole collapse, increase of excess pore water pressure and even liquefaction of sandy soil, which instead weakens the strength of the soil and has high construction risk. SUMMARY

[0003] In view of the above defects in the prior art, a supporting method and system suitable for low-cohesion sandy soil foundation pit are provided, which provide greater anti-sliding force for slope support to better resist slope deformation.

[0004] The technical scheme adopted by the present application to solve the above technical problems is as follows: In a first aspect, a supporting method suitable for low-cohesion sandy soil foundation pit comprises S1: determining a supporting surface and inserting a first steel sheet pile on the supporting surface; S2: excavating the original ground on the excavation side of the first steel sheet pile to a certain depth to form an excavation side working surface; S3: installing a steel strand on the excavation side working surface, the first end of the steel strand extending to the soil layer of a certain depth on the non-excavation side of the first steel sheet pile through the first steel sheet pile; S4: grouting in the soil layer around the end of the first end of the steel strand to form a consolidation body, the consolidation body wrapping around the end of the first end of the steel strand; S5: after the consolidation body reaches a certain strength, tensioning the second end of the steel strand, the second end of the steel strand being fixed on the excavation side of the first steel sheet pile through the tensioning structure; S6: excavating the excavation side working surface to form an excavation side design surface, and performing subsequent other construction procedures on the excavation side design surface.

[0005] According to the above technical scheme, step A1 is added between steps S5 and S6 A1: Drive second sheet piles parallel to and spaced apart from the first sheet piles on the excavation side working face, and grout into the soil layer between the second sheet piles and the first sheet piles to form a grouting pile consolidation body.

[0006] According to the above technical solution, several reinforcing steel plates are fixed between the first steel sheet pile and the second row of steel sheet piles.

[0007] According to the above technical solution, step A11 is added to step A1; At least two reinforcing steel plates are fixed between the first row of sheet piles and the second row of sheet piles; the lower reinforcing steel plate is installed. A11: Support frames are installed at intervals on the sides of the sheet piles between the reinforcing steel plates, and external pipelines are erected on the support frames. Install the remaining reinforcing steel plates.

[0008] According to the above technical solution, the grouting process within the soil layer is as follows: Insert a perforated pipe into the end area of ​​the first end of the steel strand, or in the area between the first and second steel sheet piles, and perform grouting; after grouting is completed, pull out the perforated pipe; The perforated tube is a circular tube structure, with several perforated tube holes for grouting at the end of the circular tube.

[0009] Secondly, support systems suitable for low-cohesion sand foundation pits, including... The first sheet pile is driven into the support surface, and the first sheet pile divides the original ground into the excavation side and the non-excavation side; an excavation working face is provided on the excavation side of the first sheet pile. The consolidated body is located within a soil layer at a predetermined depth on the non-excavation side of the first sheet pile. The first ends of several steel strands are embedded in the consolidation body, and a tensioning structure is fixed on the side of the first steel sheet pile excavation side; after tensioning, the first ends of several steel strands are fixed at intervals on the tensioning structure.

[0010] According to the above technical solution, it also includes a second sheet pile, which is driven into the excavation side working face, and a set distance is left between the second sheet pile and the first sheet pile; a pile consolidation body is provided in the soil layer between the first sheet pile and the second sheet pile, and several reinforcing steel plates are provided in the area above the excavation side working face between the first sheet pile and the second sheet pile.

[0011] According to the above technical solution, it also includes a support frame, with at least two reinforcing steel plates fixed between the first steel sheet pile and the second row of steel sheet piles, and the reinforcing steel plates are arranged at intervals in the vertical direction; the support frame is located between the two reinforcing steel plates, and the support frame is fixed on the side of the first steel sheet pile or the second steel sheet pile located between the piles, and external pipelines are erected and fixed on the support frame.

[0012] According to the above technical solution, it also includes the excavation design face; When only the first sheet pile is installed, the excavation is further excavated on the working face of the excavation side to form the excavation design face; When a first sheet pile and a second sheet pile are provided, the excavation is further excavated on the working face of the excavation side away from the second sheet pile to form the excavation design face.

[0013] According to the above technical solution, the tensioning structure includes a pad and a channel steel. The channel steel is horizontally arranged and fixed on the first steel sheet pile. Several pads are fixed at intervals on the channel steel. The pads are provided with threading holes for fixing the steel strands. The steel strands are tensioned by passing through the threading holes and then fixed at the threading holes.

[0014] The present invention has the following beneficial effects: 1. After the first sheet pile is driven, grouting is used on the non-excavation side to form a consolidated body within the soil layer. Steel strands are used to connect the consolidated body and the first sheet pile, providing effective support for the first sheet pile. This solves the problem of insufficient pull-out resistance in low-cohesion soil during support construction, making it unsuitable for anchor cable construction. It provides greater anti-sliding force for support projects in low-cohesion soil areas and narrow spaces, better resisting slope deformation.

[0015] 2. A second row of sheet piles is installed, and grout is injected between the second and first sheet piles to form a consolidated inter-pile structure. The first sheet pile, the consolidated inter-pile structure, and the second row of sheet piles form an integral structure, which functions similarly to a gravity retaining wall or a large-diameter concrete pile. This achieves synergistic load-bearing. In cases where the soil cohesion is low or the support depth is large, this provides a greater supporting force to the slope and enhances the overall support capacity of the support system. In addition, after soil reinforcement, the impermeability of the sheet piles is enhanced, greatly reducing the risk of seepage.

[0016] 3. A reinforcing steel plate is added between the first sheet pile and the second sheet pile to further enhance the strength of the overall structure formed by the first sheet pile, the pile consolidation body, and the second row of sheet piles, thereby further enhancing the overall support capacity of the support system; in addition, it provides an installation space for the laying of external pipelines.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0019] Figure 1 This invention provides a structural schematic diagram of the support system (support system) in Embodiment 1. Figure 2 This invention provides a structural schematic diagram of the support system (support system) in Embodiment 2. Figure 3 This is a structural schematic diagram of the support system (support system) provided in Embodiment 3 of the present invention. Figure 4 This is a schematic diagram of the flower tube provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a single sheet pile used in the first and second sheet piles provided in the embodiments of the present invention. Figure 6 This is a schematic diagram of the connection between the steel strand and the tensioning structure according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the first steel sheet pile driven according to an embodiment of the present invention (support method, embodiments 1-3). Figure 8 This is a schematic diagram of the installation of steel strands on the first steel sheet pile according to an embodiment of the present invention (support method, embodiment 1-3). Figure 9 This is a schematic diagram of the construction of the perforated pipe according to an embodiment of the present invention (support method, embodiments 1-3); Figure 10 This is a schematic diagram of the construction of the solidified body according to an embodiment of the present invention (support method, embodiment 1-3). Figure 11 This is a schematic diagram of the steel strand tensioning construction (support method, embodiments 1-3) provided by the present invention. Figure 12 This is a construction diagram of the second steel sheet pile provided by the present invention (support method, embodiment 2-3); Figure 13 This is a schematic diagram of the construction of the perforated pipe structure for the pile consolidation body provided in the present invention (support method, embodiment 2-3). Figure 14 This is a schematic diagram of the construction of the pile consolidation body according to an embodiment of the present invention (support method, embodiment 2-3). Figure 15 This is a schematic diagram of the construction of the reinforced steel plate according to an embodiment of the present invention (support method, embodiment 2-3); Figure 16 This is a schematic diagram of the construction of external pipelines (support method, embodiment 3) provided by the present invention. In the diagram, 1. First sheet pile; 2. Excavation side; 2-1. Excavation side working face; 2-2. Excavation design face; 3. Non-excavation side; 4. Consolidated body; 5. Pipe; 5-1. Pipe hole; 6. Steel strand; 7. Tensioning structure; 7-1. Pad plate; 7-2. Channel steel; 7-3. Wire hole; 8. Second sheet pile; 9. Consolidated body between piles; 10. Reinforcing steel plate; 11. Support frame; 12. External pipeline. Detailed Implementation

[0020] The following is in conjunction with the appendix Figures 1-16 The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0021] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Reference Figures 1-16 As shown, the present invention provides a support system for foundation pits in low-cohesion sand.

[0024] Example 1 like Figure 1 As shown, including The first sheet pile 1 is driven into the support surface, and the first sheet pile divides the original ground into the excavation side 2 and the non-excavation side 3; an excavation side working surface 2-1 is provided on the excavation side of the first sheet pile; The solidified body 4 is located in the soil layer at a set depth on the non-excavation side of the first sheet pile; the solidified body is formed by grouting through the perforated pipe 5, and the perforated pipe is pulled out after grouting is completed.

[0025] The first ends of several steel strands 6 are embedded in the consolidation body, and a tensioning structure 7 is fixed on the side of the excavation side of the first sheet pile. After tensioning, the first ends of the several steel strands are fixed to the tensioning structure at intervals. Finally, the excavation design face 2-2 is formed by further excavation on the working face of the excavation side.

[0026] Preferred, such as Figure 5 As shown, the tensioning structure includes a pad 7-1 and a channel steel 7-2. The channel steel is horizontally arranged and fixed on the first sheet pile. Several pads are fixed at intervals on the channel steel. A threading hole 7-3 for fixing the steel strand is fixed on the pad. The steel strand passes through the threading hole and is tensioned and then fixed at the threading hole.

[0027] This support system is used when the soil layer of the foundation pit has high cohesion or the support depth is shallow. After the first sheet pile is driven, grouting is used on the non-excavation side to form a consolidated body in the soil layer. Steel strands are used to connect the consolidated body and the first sheet pile, providing effective support for the first sheet pile. This solves the problems of insufficient pull-out resistance in low-cohesion soil during support construction, making it unsuitable for anchor cable construction. It provides greater anti-sliding force for support projects in low-cohesion soil areas and narrow spaces, thus better resisting slope deformation.

[0028] Example 2 like Figure 2 As shown, including The first sheet pile is driven into the support surface, and the first sheet pile divides the original ground into the excavation side and the non-excavation side; an excavation working face is provided on the excavation side of the first sheet pile. The consolidated body is located within a soil layer at a predetermined depth on the non-excavation side of the first sheet pile. The first ends of several steel strands are embedded in the consolidation body, and a tensioning structure is fixed on the side of the first steel sheet pile excavation side; after tensioning, the first ends of several steel strands are fixed at intervals on the tensioning structure.

[0029] The second sheet pile 8 is driven into the excavation side working face, with a predetermined spacing between it and the first sheet pile. An inter-pile consolidation body 9 is provided in the soil layer between the first and second sheet piles. Several reinforcing steel plates 10 are provided in the area above the excavation side working face between the first and second sheet piles. The inter-pile consolidation body is formed by grouting through perforated pipes, which are then removed after grouting. There is a certain distance between the second row of sheet piles and the first sheet piles; this distance can be determined through stress calculations. Preferably, the reinforcing steel plates are located above the excavation side working face and at the ends of the first and second sheet piles.

[0030] Subsequently, further excavation was carried out on the excavation side working face away from the second sheet pile to form the excavation design face.

[0031] Preferred, such as Figure 5 As shown, the tensioning structure includes pads and channel steel. The channel steel is horizontally arranged and fixed on the first sheet pile. Several pads are fixed at intervals on the channel steel. The pads are provided with threading holes for fixing the steel strands. The steel strands are tensioned by passing through the threading holes and then fixed at the threading holes.

[0032] This support system is used when the cohesion of the soil layer in the foundation pit is low or the support depth is deep. A second row of sheet piles is installed, and grout is injected between the second and first sheet piles to form a consolidated inter-pile structure. The first sheet pile, the consolidated inter-pile structure, and the second row of sheet piles form an integral structure, functioning similarly to a gravity retaining wall or large-diameter concrete piles. This achieves synergistic load-bearing capacity. For situations with low soil cohesion or deep support, this system provides greater support to the slope, enhancing the overall support capacity of the support system. Furthermore, soil reinforcement enhances the impermeability of the sheet piles, significantly reducing the risk of seepage.

[0033] Example 3 like Figure 3 As shown, including The first sheet pile is driven into the support surface, and the first sheet pile divides the original ground into the excavation side and the non-excavation side; an excavation working face is provided on the excavation side of the first sheet pile. The consolidated body is located within a soil layer at a predetermined depth on the non-excavation side of the first sheet pile. The first ends of several steel strands are embedded in the consolidation body, and a tensioning structure is fixed on the side of the first steel sheet pile excavation side; after tensioning, the first ends of several steel strands are fixed at intervals on the tensioning structure.

[0034] The second sheet pile is driven into the excavation face, with a predetermined spacing between it and the first sheet pile. An inter-pile consolidation body is installed in the soil layer between the first and second sheet piles. Several reinforcing steel plates are installed above the excavation face between the first and second sheet piles. The inter-pile consolidation body is formed by grouting through perforated pipes, which are then removed after grouting. There is a certain distance between the second row of sheet piles and the first sheet piles; this distance can be determined through stress calculations. Preferably, the reinforcing steel plates are located above the excavation face and at the ends of the first and second sheet piles.

[0035] A support frame 11 is constructed with at least two reinforcing steel plates fixed between the first and second row of sheet piles, the reinforcing steel plates being spaced apart vertically. The support frame is located between the two reinforcing steel plates and is fixed to the side of the first or second sheet pile located on the pile-to-pile consolidation body. An external pipeline 12 is mounted and fixed on the support frame. Subsequently, further excavation is carried out on the excavation face away from the second sheet pile to form the excavation design face.

[0036] Preferred, such as Figure 5 As shown, the tensioning structure includes pads and channel steel. The channel steel is horizontally arranged and fixed on the first sheet pile. Several pads are fixed at intervals on the channel steel. The pads are provided with threading holes for fixing the steel strands. The steel strands are tensioned by passing through the threading holes and then fixed at the threading holes.

[0037] When the cohesion of the soil layer in the foundation pit is low or the support depth is deep, if there are high requirements for on-site safety and civilized construction and high safety and civilized construction goals, this support system can be used. It adds support frames and other structures, which is conducive to the layout of on-site pipelines.

[0038] This invention also provides a support method for foundation pits in low-cohesion sand. Example 1 Example 1, based on a support system for low-cohesion sand foundation pits, such as Figure 1 , 4 As shown in -11, the method includes S1: Determine the support surface and drive the first steel sheet pile into the support surface; S2: Excavate the original ground to a set depth on the excavation side of the first sheet pile and form the excavation side working surface; S3: Install steel strands on the excavation side working face. The first end of the steel strand passes through the first sheet pile and extends into the soil layer at a certain depth on the non-excavation side of the first sheet pile. S4: Grouting is performed within the soil layer surrounding the first end of the steel strand to form a consolidated body, which wraps around the end of the first steel strand. Specifically, after the steel strand is installed, a perforated pipe is driven into the end region of the first steel strand, and grouting is carried out. After grouting is completed, the perforated pipe is pulled out, and a consolidated body is formed in the grouting area below the original ground surface. A strong bond is formed between the consolidated body and the steel strand, which provides tension for the first sheet pile.

[0039] S5: After the consolidated body reaches the set strength, the second end of the steel strand is tensioned. The second end of the steel strand is fixed to the excavated side of the first sheet pile through a tensioning structure. Specifically, after the consolidated body has a certain strength, channel steel and pads are installed at the designed position on the side of the first sheet pile and tensioned to form a complete anchor cable structure, thereby providing tension to the first sheet pile.

[0040] S6: Excavate the working face on the excavation side to form the design face on the excavation side; carry out subsequent construction procedures on the design face on the excavation side.

[0041] This support method is adopted when the soil layer of the foundation pit has high cohesion or the support depth is shallow. After the first sheet pile is driven, grouting is used on the non-excavation side to form a consolidated body in the soil layer. Steel strands are used to connect the consolidated body and the first sheet pile, providing effective support for the first sheet pile. This solves the problems of insufficient pull-out resistance in low-cohesion soil during support construction, making it unsuitable for anchor cable construction. It provides greater anti-sliding force for support projects in low-cohesion soil areas and narrow spaces, thus better resisting slope deformation.

[0042] Example 2 Example 2, based on a support system for low-cohesion sand foundation pits, such as Figure 2 , 4 As shown in Figure -15, the method includes S1: Determine the support surface and drive the first steel sheet pile into the support surface.

[0043] S2: Excavate the original ground to a set depth on the excavation side of the first sheet pile to form the excavation side working surface.

[0044] S3: Install steel strands on the excavation side working face. The first end of the steel strand passes through the first sheet pile and extends into the soil layer at a certain depth on the non-excavation side of the first sheet pile.

[0045] S4: Grouting is performed within the soil layer surrounding the first end of the steel strand to form a consolidated body, which wraps around the end of the first steel strand. Specifically, after the steel strand is installed, a perforated pipe is driven into the end region of the first steel strand, and grouting is carried out. After grouting is completed, the perforated pipe is pulled out, and a consolidated body is formed in the grouting area below the original ground surface. A strong bond is formed between the consolidated body and the steel strand, which provides tension for the first sheet pile.

[0046] S5: After the consolidated body reaches the set strength, the second end of the steel strand is tensioned. The second end of the steel strand is fixed to the excavated side of the first sheet pile through a tensioning structure. Specifically, after the consolidated body has a certain strength, channel steel and pads are installed at the designed position on the side of the first sheet pile and tensioned to form a complete anchor cable structure, thereby providing tension to the first sheet pile.

[0047] A1: Drive second sheet piles parallel to and spaced apart from the first sheet piles on the excavation side working face, and grout into the soil layer between the second sheet piles and the first sheet piles to form a grouting pile consolidation body.

[0048] In step A1, in order to increase the rigidity of the overall structure formed by the first sheet pile, the inter-pile consolidation body, and the second row of sheet piles, several reinforcing steel plates are fixed between the first sheet pile and the second row of sheet piles.

[0049] S6: Excavate the working face on the excavation side to form the design face on the excavation side; carry out subsequent construction procedures on the design face on the excavation side.

[0050] Step A1 is added between steps S5 and S6 to provide a larger supporting force to the slope.

[0051] This support method is adopted when the cohesion of the soil layer in the foundation pit is low or the support depth is deep. A second row of sheet piles is installed, and grout is injected between the second and first sheet piles to form a consolidated inter-pile structure. The first sheet pile, the consolidated inter-pile structure, and the second row of sheet piles form an integral structure, functioning similarly to a gravity retaining wall or large-diameter concrete piles. This achieves synergistic load-bearing capacity. For situations with low soil cohesion or deep support, this method provides greater support to the slope, enhancing the overall support capacity of the support system. Furthermore, soil reinforcement enhances the impermeability of the sheet piles, significantly reducing the risk of seepage.

[0052] Example 3 Example 3, based on a support system for low-cohesion sand foundation pits, such as Figures 3-16 The method shown includes S1: Determine the support surface and drive the first steel sheet pile into the support surface.

[0053] S2: Excavate the original ground to a set depth on the excavation side of the first sheet pile to form the excavation side working surface.

[0054] S3: Install steel strands on the excavation side working face. The first end of the steel strand passes through the first sheet pile and extends into the soil layer at a certain depth on the non-excavation side of the first sheet pile.

[0055] S4: Grouting is performed within the soil layer surrounding the first end of the steel strand to form a consolidated body, which wraps around the end of the first steel strand. Specifically, after the steel strand is installed, a perforated pipe is driven into the end region of the first steel strand, and grouting is carried out. After grouting is completed, the perforated pipe is pulled out, and a consolidated body is formed in the grouting area below the original ground surface. A strong bond is formed between the consolidated body and the steel strand, which provides tension for the first sheet pile.

[0056] S5: After the consolidated body reaches the set strength, the second end of the steel strand is tensioned. The second end of the steel strand is fixed to the excavated side of the first sheet pile through a tensioning structure. Specifically, after the consolidated body has a certain strength, channel steel and pads are installed at the designed position on the side of the first sheet pile and tensioned to form a complete anchor cable structure, thereby providing tension to the first sheet pile.

[0057] A1: Drive second sheet piles parallel to and spaced apart from the first sheet piles on the excavation side working face, and grout into the soil layer between the second sheet piles and the first sheet piles to form a grouting pile consolidation body.

[0058] In step A1, in order to increase the rigidity of the overall structure formed by the first sheet pile, the inter-pile consolidation body, and the second row of sheet piles, several reinforcing steel plates are fixed between the first sheet pile and the second row of sheet piles, with at least two reinforcing steel plates fixed between the first sheet pile and the second row of sheet piles.

[0059] Specifically, after the grouting of the pile consolidation body is completed, reinforcing steel plates are welded between the first and second rows of sheet piles on the excavation side working face. Since on-site support is often located around the construction site, to standardize on-site construction and reduce trench excavation, support frames can be installed on the first and second rows of sheet piles. Pipelines can be installed above the support frames. Pipelines can be water pipes, cables, or other materials that need to be installed around the perimeter of the foundation pit. When the pipeline is a cable, the support frame must be made of insulating material or undergo insulation treatment. After the pipeline installation is completed, reinforcing steel plates are welded to the ends of the first and second rows of sheet piles to enhance the overall rigidity of the support system and increase its support capacity.

[0060] S6: Excavate the working face on the excavation side to form the design face on the excavation side; carry out subsequent construction procedures on the design face on the excavation side.

[0061] In Examples 1-3, whether grouting is performed in the soil layer around the end of the first end of the steel strand to form a solidified body, or grouting is performed in the soil layer between the second steel sheet pile and the first steel sheet pile, a perforated pipe is inserted in the area to be constructed and grouting is carried out. After grouting is completed, the perforated pipe is pulled out. The perforated pipe is a circular pipe structure with several perforated pipe holes 5-1 for grouting at the end of the circular pipe.

[0062] When the cohesion of the soil layer in the foundation pit is low or the support depth is deep, if there are high requirements for on-site safety and civilized construction and high safety and civilized construction goals, this support method can be adopted. It adds support frames and other structures, which is conducive to the layout of on-site pipelines.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A support method applicable to foundation pits in low-cohesion sand, characterized in that: include S1: Determine the support surface and drive the first steel sheet pile into the support surface; S2: Excavate the original ground to a set depth on the excavation side of the first sheet pile and form the excavation side working surface; S3: Install steel strands on the excavation side working face. The first end of the steel strand passes through the first sheet pile and extends into the soil layer at a certain depth on the non-excavation side of the first sheet pile. S4: Grouting is performed in the soil layer around the end of the first end of the steel strand to form a solidified body, which wraps around the end of the first end of the steel strand. S5: After the solidified body reaches the set strength, the second end of the steel strand is tensioned, and the second end of the steel strand is fixed to the excavated side of the first steel sheet pile through the tensioning structure. S6: Excavate the working face on the excavation side to form the design face on the excavation side; carry out subsequent construction procedures on the design face on the excavation side.

2. The support method for low-cohesion sand foundation pits according to claim 1, characterized in that: Add step A1 between steps S5 and S6; A1: Drive second sheet piles parallel to and spaced apart from the first sheet piles on the excavation side working face, and grout into the soil layer between the second sheet piles and the first sheet piles to form a grouting pile consolidation body.

3. The support method for low-cohesion sand foundation pits according to claim 2, characterized in that: Several reinforcing steel plates are fixed between the first and second rows of sheet piles.

4. The support method for low-cohesion sand foundation pits according to claim 2, characterized in that: Add step A11 within step A1; At least two reinforcing steel plates are fixed between the first row of sheet piles and the second row of sheet piles; the lower reinforcing steel plate is installed. A11: Support frames are installed at intervals on the sides of the sheet piles between the reinforcing steel plates, and external pipelines are erected on the support frames. Install the remaining reinforcing steel plates.

5. The support method for low-cohesion sand foundation pits according to any one of claims 1-4, characterized in that: The grouting process within the soil layer is as follows: Insert a perforated pipe into the end area of ​​the first end of the steel strand, or in the area between the first and second steel sheet piles, and perform grouting; after grouting is completed, pull out the perforated pipe; The perforated tube is a circular tube structure, with several perforated tube holes for grouting at the end of the circular tube.

6. A support system suitable for low-cohesion sand foundation pits, characterized in that: include The first sheet pile is driven into the support surface, and the first sheet pile divides the original ground into the excavation side and the non-excavation side; an excavation working face is provided on the excavation side of the first sheet pile. The consolidated body is located within a soil layer at a predetermined depth on the non-excavation side of the first sheet pile. The first ends of several steel strands are embedded in the consolidation body, and a tensioning structure is fixed on the side of the first steel sheet pile excavation side; after tensioning, the first ends of several steel strands are fixed at intervals on the tensioning structure.

7. The support system for low-cohesion sand foundation pits according to claim 6, characterized in that: It also includes a second sheet pile, which is driven into the working face on the excavation side, with a set distance between the second sheet pile and the first sheet pile; a pile consolidation body is provided in the soil layer between the first sheet pile and the second sheet pile, and several reinforcing steel plates are provided in the area above the working face on the excavation side between the first sheet pile and the second sheet pile.

8. The support system for low-cohesion sand foundation pits according to claim 7, characterized in that: It also includes a support frame, with at least two reinforcing steel plates fixed between the first sheet pile and the second row of sheet piles, the reinforcing steel plates being arranged at intervals in the vertical direction; the support frame is located between the two reinforcing steel plates, and the support frame is fixed on the side of the first sheet pile or the second sheet pile located between the piles, and external pipelines are erected and fixed on the support frame.

9. The support system for low-cohesion sand foundation pits according to claim 6 or 7, characterized in that: This also includes the excavation design face; When only the first sheet pile is installed, the excavation is further excavated on the working face of the excavation side to form the excavation design face; When a first sheet pile and a second sheet pile are provided, the excavation is further excavated on the working face of the excavation side away from the second sheet pile to form the excavation design face.

10. The support system for low-cohesion sand foundation pits according to claim 7, characterized in that: The tensioning structure includes pads and channel steel. The channel steel is horizontally arranged and fixed on the first sheet pile. Several pads are fixed at intervals on the channel steel. The pads are provided with threading holes for fixing steel strands. The steel strands are tensioned by passing through the threading holes and then fixed at the threading holes.

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