Supporting structure capable of reducing deformation of foundation pit close to existing tunnel

Abstract

The utility model discloses a supporting structure capable of reducing deformation of a foundation pit close to an existing tunnel, which belongs to the field of foundation pit supporting and comprises a foundation pit support, an expanded concrete panel and a steel reinforcement framework, and a plurality of transverse steel reinforcements of the steel reinforcement framework are poured with concrete to form the expanded concrete panel. The expanded concrete panel is fixedly arranged on the top of the side, close to the existing tunnel, of the foundation pit support. The supporting structure capable of reducing deformation of the foundation pit close to the existing tunnel is large in rigidity and high in deformation resistance, the integrity of a foundation pit support and surrounding soil can be improved, and the deformation quantity of the soil body of the foundation pit close to the existing tunnel is remarkably reduced.

Description

Technical Field

[0001] This utility model relates to the field of foundation pit support, and in particular to a support structure that can reduce the deformation of adjacent existing tunnel foundation pits. Background Technology

[0002] With the rapid pace of urbanization, major cities are focusing their urban development on underground space, and the rapid development of subway construction has facilitated people's travel. At the same time, the size and depth of building foundation pits are constantly increasing, and the unloading of soil and dewatering during the excavation process inevitably disturb the original soil layers. To ensure the operational safety of subway tunnels, there are generally stricter restrictions on the deformation of foundation pits adjacent to existing tunnels. In actual construction, measures such as grouting between the foundation pit and the tunnel are often used to reduce soil displacement, thereby ensuring construction safety and the stability of the tunnel structure.

[0003] A Chinese utility model patent application, "A Reinforcement Structure and Method for the Peripheral Soil Layer of a Foundation Pit Adjacent to an Existing Tunnel" (patent application number: 202310553191.3), discloses a soil reinforcement structure comprising auxiliary holes, steel casings, grouting pipes, and a water interception device. This technical solution, by pre-determining the location of tunnel deformation trends and using grouting technology for precise positioning grouting, can not only reduce the amount of grouting and save costs but also effectively control tunnel deformation. However, the construction method of excavating the soil first and then grouting for reinforcement in this solution is inconsistent with the current concept of "reinforcement first, excavation later." Furthermore, setting auxiliary holes in the foundation pit retaining wall for grouting can damage the overall integrity of the retaining wall, thus affecting the overall support effect. Therefore, this technical solution has certain limitations in application. Utility Model Content

[0004] The purpose of this invention is to provide a support structure that can reduce the deformation of existing tunnel foundation pits. It has high rigidity and strong deformation resistance, which can increase the integrity of the foundation pit support and the surrounding soil, and significantly reduce the deformation of the foundation pit soil near existing tunnels.

[0005] To achieve the above objectives, this utility model provides a support structure that can reduce the deformation of an existing tunnel pit, including a pit retaining structure, an enlarged concrete panel, and a steel reinforcement cage. Multiple transverse steel bars of the steel reinforcement cage are poured with concrete to form the enlarged concrete panel, which is fixedly installed on the top of the pit retaining structure on the side closest to the existing tunnel.

[0006] Preferably, the longitudinal reinforcing bars of the steel reinforcement cage are fixed inside the foundation pit retaining wall on the side close to the existing tunnel, and the top of the longitudinal reinforcing bars extends into the enlarged concrete panel.

[0007] Preferably, the long steel bars of the steel reinforcement cage are fixed in the grouting area, and the top of the long steel bars extends into the enlarged concrete panel.

[0008] Preferably, the long steel bars and the longitudinal reinforcing bars are welded to the transverse steel bars.

[0009] Preferably, the foundation pit retaining walls are provided with a number of concrete supports and steel supports fixed from top to bottom.

[0010] Preferably, a vertical brace is fixed between the side of the foundation pit retaining wall near the existing tunnel and the steel support. A horizontal plate is fixed at one end of the vertical brace near the steel support. A bolt hole is provided through the middle of the horizontal plate directly opposite the steel support. The bolt passes through the horizontal plate and the bolt hole and is fixedly connected to the washer at the bottom of the steel support.

[0011] Preferably, the angle between the vertical brace and the steel support is 45°.

[0012] Therefore, the present invention employs the above-mentioned support structure that can reduce the deformation of adjacent existing tunnel foundation pits, and has the following beneficial effects:

[0013] (1) The transverse steel bars of the steel reinforcement cage are poured to form an enlarged concrete panel. The longitudinal reinforcing bars of the foundation pit retaining and the long steel bars of the grouting area are welded to the transverse steel bars, connecting the originally independent foundation pit retaining and grouting reinforcement areas into a whole, thereby improving the rigidity and deformation resistance of the support structure.

[0014] (2) By setting vertical bracing between the foundation pit retaining and the steel support, the shear strength of the support structure is significantly improved, thereby further reducing the deformation of the adjacent existing tunnel foundation pit.

[0015] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the support structure of this utility model that can reduce the deformation of an existing tunnel foundation pit.

[0017] Figure Labels

[0018] 1. Excavation pit retaining wall; 2. Concrete support; 3. Steel support; 4. Longitudinal reinforcing bars; 5. Enlarged concrete panel; 6. Long reinforcing bars; 7. Horizontal reinforcing bars; 8. Vertical bracing; 9. Bolts; 10. Horizontal plate; 11. Gaskets; 12. Bolt holes; 13. Grouting area; 14. Existing tunnel. Detailed Implementation

[0019] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Example 1

[0022] like Figure 1 As shown, this utility model provides a support structure that can reduce the deformation of an existing tunnel pit, including a pit retaining wall 1, an enlarged concrete panel 5, and a steel reinforcement cage. The pit retaining wall 1 is used to block the soil and groundwater outside the pit and prevent the pit from collapsing. The steel reinforcement cage is composed of multiple transverse steel bars 7, longitudinal reinforcing steel bars 4, and long steel bars 6. The enlarged concrete panel 5 is fixedly installed on the top of the pit retaining wall 1 on the side closest to the existing tunnel 14, connecting the pit retaining wall 1 and the steel reinforcement cage into a whole, which together improves the overall performance of the support structure, reduces pit deformation, and protects the stability and safety of the existing tunnel 14.

[0023] The foundation pit retaining wall 1 uses cast-in-place piles, and the internal support includes several concrete supports 2 and steel supports 3 fixedly installed from top to bottom. Through the steel supports 3 and concrete supports 2, the load inside and outside the foundation pit can be distributed more evenly onto the foundation pit retaining wall 1, reducing local stress concentration. The concrete supports 2 and steel supports 3 significantly enhance the rigidity of the foundation pit retaining wall 1, effectively preventing deformation and collapse of the foundation pit wall, and ensuring the stability and safety of the foundation pit.

[0024] A vertical brace 8 is fixed between the side of the foundation pit retaining wall 1 closest to the existing tunnel 14 and the steel support 3, with an angle of 45° between the vertical brace 8 and the steel support 3. By installing the vertical brace 8 between the foundation pit retaining wall 1 and the steel support 3, the shear strength of the support structure can be significantly improved, enabling it to better resist lateral earth pressure and water pressure, and reducing the displacement of the foundation pit wall. A horizontal plate 10 is fixed to one end of the vertical brace 8 closest to the steel support 3. A bolt hole 12 is drilled through the middle of the horizontal plate 10 on the steel support 3. Bolts 9 pass through the horizontal plate 10 and the bolt hole 12 and are fixedly connected to the washer 11 at the bottom of the steel support 3. The vertical brace 8 and the steel support 3 are connected by the horizontal plate 10 and bolts 9. This connection method not only increases the rigidity of the foundation pit retaining wall 1 but also improves the reliability of the connection, ensuring the stability and safety of the support structure under complex geological conditions.

[0025] Multiple transverse reinforcing bars 7 of the steel reinforcement cage are poured with concrete to form an enlarged concrete panel 5, which significantly enhances the rigidity of the enlarged concrete panel 5 and improves its ability to resist external loads. The longitudinal reinforcing bars 4 of the steel reinforcement cage are fixed inside the pit retaining wall 1 on the side closest to the existing tunnel 14, with their tips extending into the enlarged concrete panel 5, tightly connecting the enlarged concrete panel 5 to the pit retaining wall 1. The long reinforcing bars 6 of the steel reinforcement cage are fixed in the grouting area 13, enhancing the stability of the grouting area 13 and preventing soil disturbance caused by soil unloading and dewatering during pit excavation. The tips of the long reinforcing bars 6 also extend into the enlarged concrete panel 5, tightly connecting the enlarged concrete panel 5 to the grouting area 13. The long reinforcing bars 6 and the longitudinal reinforcing bars 4 are all welded to the transverse reinforcing bars 7, connecting the originally independent pit retaining wall 1 and grouting area 13 into a whole through the enlarged concrete panel 5 and the steel reinforcement cage, forming a support system with strong integrity and high deformation resistance.

[0026] Working principle: Before the excavation of the foundation pit, the construction unit, according to the design plan, sets up grouting holes and reinforces the soil between the existing tunnel 14 and the foundation pit area with grouting. Before the grout initially sets, the prefabricated long steel bars 6 are inserted into the grouting holes. The longitudinal reinforcing bars 4 and the long steel bars 6 in the foundation pit retaining wall 1 are welded together with the transverse steel bars 7 to form a steel skeleton, and concrete is poured to form an enlarged concrete panel 5. During the excavation of the foundation pit, the principle of "grooving and supporting, supporting before excavation, layered excavation, and strictly prohibiting over-excavation" is adhered to. Vertical bracing 8 is added between the foundation pit retaining wall 1 and the steel support 3 on the side adjacent to the existing tunnel 14. Bolts 9 further connect the foundation pit retaining wall 1 and the steel support 3 through the horizontal plate 10 of the vertical bracing 8, the bolt holes 12 of the steel support 3, and the washers 11, thereby increasing the constraint on the deformation of the foundation pit retaining wall 1 and the surrounding soil on the side adjacent to the existing tunnel 14.

[0027] Therefore, the present invention adopts the above-mentioned support structure that can reduce the deformation of the foundation pit of an adjacent existing tunnel. It has high rigidity and strong deformation resistance, which can increase the integrity of the foundation pit support and the surrounding soil, and significantly reduce the deformation of the foundation pit soil of the adjacent existing tunnel.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. A support structure capable of reducing deformation of a foundation pit adjacent to an existing tunnel, characterized by: The base pit enclosure, the expanded concrete panel and the steel reinforcement frame are included, and the expanded concrete panel is fixed on the top of the side of the base pit enclosure close to the existing tunnel.

2. The supporting structure capable of reducing deformation of a foundation pit adjacent to an existing tunnel according to claim 1, characterized in that: The longitudinal stress steel of the steel reinforcement frame is fixed inside the side of the base pit enclosure close to the existing tunnel, and the top end of the longitudinal stress steel is deep into the expanded concrete panel.

3. The support structure of claim 2, wherein: The long steel of the steel reinforcement frame is fixed in the grouting area, and the top end of the long steel is inserted into the expanded concrete panel.

4. The supporting structure capable of reducing deformation of a foundation pit adjacent to an existing tunnel according to claim 3, characterized in that: The long steel and the longitudinal stress steel are welded with the transverse steel.

5. The supporting structure capable of reducing deformation of a foundation pit adjacent to an existing tunnel according to claim 1, characterized in that: A plurality of concrete supports and steel supports are fixed from top to bottom between the base pit enclosures.

6. The support structure of claim 5, wherein: A vertical inclined strut is fixed between the side of the base pit enclosure close to the existing tunnel and the steel support, one end of the vertical inclined strut close to the steel support is fixed with a horizontal plate, the middle part of the horizontal plate opposite to the steel support is penetrated with a bolt hole, and the bolt is fixedly connected with the gasket at the bottom of the steel support through the horizontal plate and the bolt hole.

7. The support structure of claim 6, wherein: The included angle between the vertical inclined strut and the steel support is 45°.

Images