A foundation pit supporting device

Abstract

The utility model discloses a kind of foundation pit supporting devices, including anchor rod assembly embedded in the soil body of foundation pit side wall, spray concrete surface layer covering on the wall of foundation pit and be used for exerting and locking prestress tension locking assembly;The anchor rod assembly is composed of prestressed steel strand, spiral corrugated steel pipe corrugated sleeve and the isolation sheath pipe of outer cover, and prestressed steel strand is connected with the inner end of corrugated sleeve by detachable anchor device thread and is formed detachable rigid composite pole body, the outer wall of isolation sheath pipe is equipped with the positioning support of guide mouth, ensure that anchor rod is in the middle and guide grouting to hole bottom and form primary grouting body;The device actively restricts deformation of foundation pit side wall by exerting prestress, and constitutes high stiffness reinforced body to resist adjacent building additional load, after construction is completed, detachable anchor device can be released and core stress component is extracted integrally, realize safety, convenient, complete recovery, significantly improve the security and economy of foundation pit construction under complex environment of city center.

Description

Technical Field

[0001] This utility model relates to the field of building construction technology, specifically to a foundation pit support device. Background Technology

[0002] When excavating foundation pits in urban centers, complex conditions often arise due to their proximity to existing buildings. The core challenges of such projects are: First, the unloading during excavation inevitably causes stress release and displacement in the surrounding soil. This deformation directly disturbs the foundations of adjacent existing buildings, potentially leading to new or uneven settlement and seriously threatening their structural safety. Second, the self-weight and load of the existing buildings (especially frame or load-bearing structures) act as additional stress, transmitted through the soil to the foundation pit support system, creating additional thrust or bending moment. This necessitates extremely high stiffness and stability in the support structure. Existing removable support solutions are either complex and inefficient to remove, or lack sufficient stiffness, making it difficult to effectively control foundation pit deformation to protect existing buildings while achieving safe and convenient complete recovery. Utility Model Content

[0003] The purpose of this utility model is to provide a foundation pit support device, which aims to improve the problems of insufficient support stiffness and passive deformation control in existing removable support schemes when working close to existing buildings.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A foundation pit support device includes an anchor assembly embedded in the soil of the foundation pit sidewall, a shotcrete surface layer, and a tensioning and locking assembly for applying and locking prestress.

[0006] The sidewall of the foundation pit is provided with inclined grouting holes. The anchor bolt assembly is installed in the grouting holes. The anchor bolt assembly includes a prestressed steel strand, a corrugated sleeve is provided on the outer sleeve of the prestressed steel strand, an isolation sleeve is provided on the outer sleeve of the corrugated sleeve, and a detachable anchor is provided at the end of the prestressed steel strand. The end of the corrugated sleeve is connected to the detachable anchor by threads. Through the detachable anchor, the prestressed steel strand and the corrugated sleeve form a detachable rigid connection at the inner end of the grouting hole.

[0007] The grouting borehole is filled with primary grout that encapsulates the anchor bolt assembly; the shotcrete surface layer covers the pit wall.

[0008] The tensioning and locking assembly is located on the outer surface of the shotcrete surface layer and includes a pressure plate, a dispersion guide, and a tensioning end anchor. The pressure plate and the dispersion guide are fixed to the shotcrete surface layer and are used to anchor the corrugated sleeve and the isolation sleeve that pass through the grouting borehole. The tensioning end anchor is used to lock the outer end of the prestressed steel strand.

[0009] Furthermore, the isolation sheath is made of high-density polyethylene or polyvinyl chloride.

[0010] Furthermore, the corrugated sleeve is a spiral corrugated steel pipe, and the outer surface of the spiral corrugated steel pipe is provided with continuous spiral ribs.

[0011] Furthermore, the pit wall is also covered with a steel mesh, and the shotcrete surface layer covers the steel mesh.

[0012] Furthermore, multiple positioning brackets are spaced apart along the length of the outer wall of the isolation sleeve, and the positioning brackets are supported on the inner wall of the grouting borehole.

[0013] Furthermore, the outer edge of the positioning bracket is provided with several guide ports, and the guide ports on the outer edges of two adjacent positioning brackets are arranged correspondingly.

[0014] Furthermore, a cutting mark sleeve is provided between the dispersion guide and the tensioning end anchor, and the cutting mark sleeve is used to mark the cutting position of the prestressed steel strand.

[0015] Furthermore, the pit sidewall is constructed with support piles as a retaining structure, and the shotcrete surface layer covers the surface of the retaining structure; the tensioning and locking assembly also includes a waist beam set on the surface of the retaining structure, and the pressure plate and the dispersion guide are fixedly installed on the waist beam.

[0016] By adopting the above technical solution, this utility model has the following advantages compared with the prior art:

[0017] (1) This utility model effectively ensures the safety of adjacent existing buildings by actively controlling and forming a high-rigidity reinforced body from the core load-bearing component; In response to the core challenge of soil displacement caused by excavation and unloading of the foundation pit, which disturbs the foundation of the existing building, this utility model achieves active constraint on the deformation of the side wall of the foundation pit by applying prestress, rather than passive bearing, thereby significantly suppressing the spread of soil displacement; More importantly, the rigid composite rod formed by the threaded connection of "prestressed steel strand" and "corrugated sleeve" constitutes a high-rigidity reinforced body, whose bending and compressive strength is far superior to that of traditional single soil nails or flexible anchors. This characteristic enables it to effectively resist the additional load and bending moment transmitted from the existing building through the soil, greatly reducing the impact of foundation pit construction on the foundation of adjacent existing buildings, fundamentally preventing harmful uneven settlement, and ensuring structural safety;

[0018] (2) The device of this utility model has a compact structure and clear component functions; the “dispersed guide tube” ensures the smooth transmission of force flow at the orifice, and the “cutting mark sleeve” clarifies the recycling node, making the construction process more standardized; the entire support system is self-contained and does not need to be rigidly connected to the existing building foundation, which minimizes direct construction disturbance and is very suitable for foundation pit projects in urban central areas with limited space and sensitive environment.

[0019] In summary, this utility model effectively solves all the key challenges mentioned in the background art, and provides a foundation pit support device that can actively control deformation, has extremely high rigidity to protect adjacent buildings, and can achieve safety, convenience and complete recycling, thus achieving significant technological progress. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the construction and installation of the foundation pit support device described in this utility model;

[0021] Figure 2 This is a structural schematic diagram of the foundation pit support device described in this utility model;

[0022] Figure 3 This is a schematic diagram of the anchor bolt assembly structure;

[0023] Figure 4 This is a cross-sectional view of the anchor bolt assembly;

[0024] Figure 5 This is a schematic diagram of the positioning bracket.

[0025] Figure 6 This is an end view of the positioning bracket.

[0026] Explanation of reference numerals in the attached drawings: 100, Anchor bolt assembly; 101, Shotcrete surface layer; 102, Tensioning and locking assembly; 103, Grouting borehole; 1, Prestressed steel strand; 2, Corrugated sleeve; 3, Isolation sleeve; 4, Positioning bracket; 5, Guide port; 6, Primary grouting body; 7, Detachable anchor; 8, Reinforcing mesh; 9, Bearing plate; 10, Dispersion guide pipe; 11, Tensioning end anchor; 12, Cutting mark sleeve. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0028] Additionally, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are all based on the orientation or positional relationship shown in the accompanying drawings. They are merely for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element of this utility model must have a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] When an element is referred to as being "fixed to," "set on," or "contained on" another element, it can be directly on or indirectly on that other element. When an element is referred to as being "connected to," it can be directly connected to or indirectly connected to that other element.

[0030] Unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] like Figure 1 As shown, this utility model provides a foundation pit support device suitable for use adjacent to existing buildings. The device is applied to foundation pits with support piles 13 as retaining structures. The device consists of an anchor rod assembly 100 embedded in the soil of the foundation pit sidewall, a shotcrete surface layer 101 covering the surface of the support piles 13, and a tensioning and locking assembly 102 for applying and locking prestress.

[0032] like Figure 2 As shown, grouting holes 103 are drilled along the design angle on the sidewall of the foundation pit. Anchor bolt assemblies 100 are arranged inside the grouting holes 103. The core load-bearing component is a prestressed steel strand 1, which is made of multiple strands of high-strength steel wire twisted together, used to resist the lateral earth pressure of the foundation pit and the additional load transmitted from the existing building. Figure 3 and Figure 4 As shown, the prestressed steel strand 1 is sheathed with a corrugated sleeve 2. This corrugated sleeve 2 is a spiral corrugated steel pipe with continuous spiral ribs on its outer surface, which significantly improves the sleeve's compressive and bending stiffness and enhances its interlocking force with the grouting body. A further isolation sleeve 3 is fitted over the corrugated sleeve 2. This isolation sleeve 3 is made of high-density polyethylene or polyvinyl chloride, with a smooth surface. It allows for the formation of a small gap between the isolation sleeve 3 and the corrugated sleeve 2 during later removal, reducing frictional resistance and enabling the core component to be easily extracted and recovered after the project is completed. Multiple positioning supports 4 are spaced along the length of the outer wall of the isolation sleeve 3, such as... Figure 5 and Figure 6As shown, the positioning bracket 4 is supported on the inner wall of the grouting borehole 103 to keep the anchor bolt assembly 100 centered. On the other hand, its outer edge is provided with several guide ports 5. The guide ports 5 of two adjacent positioning brackets 4 correspond to each other, which can provide a channel for the grouting hose to guide the grout to the bottom of the hole smoothly, ensuring the formation of a full primary grout body 6. The grout body 6 wraps around and fixes the entire anchor bolt assembly 100 to ensure long-term stability.

[0033] To achieve a detachable connection of the core components, the inner end of the prestressed steel strand 1 is threaded to the detachable anchor 7, and the inner end of the corrugated sleeve 2 is also threaded to the detachable anchor 7, thus forming a detachable rigid connection within the grouting borehole 103. When the main foundation pit project is completed and the support needs to be removed, simply release the detachable anchor 7, and the prestressed steel strand 1 along with the corrugated sleeve 2 can be pulled out as a whole. The isolation sleeve 3, being tightly integrated with the primary grouting body 6, can remain in the hole, ensuring safety, convenience, and improved recovery efficiency.

[0034] First, a steel mesh 8 is laid on the outer side of the pit wall, and then shotcrete is sprayed to form a shotcrete surface layer 101. This surface layer serves to retain soil, transfer loads, and provide reliable support for the tensioning and locking components 102. A bearing plate 9 and a distribution guide 10 are installed on the outer surface of the shotcrete surface layer 101 to anchor the corrugated sleeve 2 and isolation sleeve 3 extending from the borehole, and to evenly transfer the prestressed load to the surface layer. A tensioning end anchor 11 is installed on the outer side of the distribution guide 10 to apply and lock the prestressed steel strands 1, ensuring the rigidity and stability of the pit support. A cutting mark sleeve 12 is fitted between the distribution guide 10 and the tensioning end anchor 11 to mark the cutting position of the prestressed steel strands 1, facilitating precise cutting later and ensuring safe and efficient demolition operations. In addition, after the shotcrete surface layer 101 is completed, a continuous waist beam 14 can be installed on the surface of the support piles 13 along the elevation of the anchor bolt borehole. The bearing plate 9 and the dispersion guide 10 should be pre-embedded or fixed in the waist beam to ensure that the tension load is effectively transferred through the waist beam 14 to the support pile 13, which is the main load-bearing component.

[0035] During construction, after drilling inclined grouting boreholes 103 on the sidewall of the foundation pit according to the design, the prestressed steel strands 1, corrugated sleeves 2 and isolation sleeves 3 are pre-assembled on the ground according to the assembly procedure and then lowered into the boreholes: first, the detachable anchor 7 is installed and fixed to the inner end of the prestressed steel strands 1, and then the inner end of the corrugated sleeve 2 is connected to the detachable anchor 7 through threads, so that the prestressed steel strands 1 and the corrugated sleeve 2 form a detachable rigid connection at the inner end of the borehole. Then, the isolation sleeve 3 is placed together with the positioning bracket 4 and the grouting hose is guided to the bottom of the hole by the guide port 5 of the positioning bracket 4. Grouting is performed to form a primary grouting body 6 covering the anchor assembly 100. After the grouting body 6 reaches the design strength and the sprayed concrete surface layer 101 and steel mesh 8 are completed, the bearing plate 9, the dispersion guide 10 and the tensioning end anchor 11 are installed on the outer surface of the sprayed concrete surface layer 101. The prestressed steel strand 1 is applied with a jack and locked with the tensioning end anchor 11. When the foundation pit project is completed and the support needs to be removed, the exposed prestressed steel strand (1) is first cut at the cutting mark sleeve (12). Then, the exposed end of the prestressed steel strand (1) is clamped and rotated with a special tool (such as a hydraulic clamp or a screwdriver). The rotation torque is transmitted to the inner end of the grouting borehole (103) through the steel strand itself, driving the detachable anchor (7) to rotate and loosen the threaded connection between it and the end of the corrugated sleeve (2). After the inner end connection is released, the prestressed steel strand (1) and the corrugated sleeve (2) can be pulled out of the hole as a whole using a pulling device or a jack. Because the isolation sleeve (3) is tightly integrated with the primary grouting body (6), it can be permanently left in the hole, thereby achieving the safe recovery of the core load-bearing component.

[0036] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A foundation pit support device, characterized in that: This includes anchor bolt assemblies embedded in the soil of the foundation pit sidewall, shotcrete surface layer, and tensioning and locking assemblies for applying and locking prestress. The sidewall of the foundation pit is provided with inclined grouting holes. The anchor bolt assembly is installed in the grouting holes. The anchor bolt assembly includes a prestressed steel strand, a corrugated sleeve is provided on the outer sleeve of the prestressed steel strand, an isolation sleeve is provided on the outer sleeve of the corrugated sleeve, and a detachable anchor is provided at the end of the prestressed steel strand. The end of the corrugated sleeve is connected to the detachable anchor by threads. Through the detachable anchor, the prestressed steel strand and the corrugated sleeve form a detachable rigid connection at the inner end of the grouting hole. The grouting borehole is filled with primary grout that encapsulates the anchor bolt assembly; the shotcrete surface layer covers the pit wall. The tensioning and locking assembly is located on the outer surface of the shotcrete surface layer and includes a pressure plate, a dispersion guide, and a tensioning end anchor. The pressure plate and the dispersion guide are fixed to the shotcrete surface layer and are used to anchor the corrugated sleeve and the isolation sleeve that pass through the grouting borehole. The tensioning end anchor is used to lock the outer end of the prestressed steel strand.

2. The foundation pit support device according to claim 1, characterized in that: The isolation sheath is made of high-density polyethylene or polyvinyl chloride.

3. The foundation pit support device according to claim 1, characterized in that: The corrugated sleeve is a spiral corrugated steel pipe, and the outer surface of the spiral corrugated steel pipe is provided with continuous spiral ribs.

4. The foundation pit support device according to claim 1, characterized in that: The pit wall is also covered with a steel mesh, and the shotcrete surface layer covers the steel mesh.

5. The foundation pit support device according to claim 1, characterized in that: Multiple positioning brackets are spaced apart along the length of the outer wall of the isolation sheath, and the positioning brackets are supported on the inner wall of the grouting borehole.

6. The foundation pit support device according to claim 5, characterized in that: The outer edge of the positioning bracket is provided with several guide ports, and the guide ports on the outer edges of two adjacent positioning brackets are arranged correspondingly.

7. The foundation pit support device according to claim 1, characterized in that: A cutting mark sleeve is also provided between the dispersion guide and the tensioning end anchor. The cutting mark sleeve is used to mark the cutting position of the prestressed steel strand.

8. The foundation pit support device according to claim 7, characterized in that: The pit sidewall is constructed with support piles as a retaining structure, and the shotcrete surface layer covers the surface of the retaining structure; the tensioning and locking assembly also includes a waist beam set on the surface of the retaining structure, and the pressure plate and the dispersion guide are fixedly installed on the waist beam.

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