A composite structure of a pile wall of an underground station

Abstract

The utility model discloses a kind of underground station pile wall composite structures, including underground station structure and the foundation pit enclosure stake of being set in the outer side of underground station structure, the sidewall bottom joist of being equipped with in the lower side of underground station structure two sides, transverse reserved reinforcement is equipped in the foundation pit enclosure stake, first connection reinforcement is correspondingly equipped in the sidewall bottom joist, and the foundation pit enclosure stake is close to the side of underground station structure and is equipped with the reinforcement connection component for the transverse reserved reinforcement and the first connection reinforcement connection. The utility model analysis foundation pit enclosure stake base is used as the composite structure of underground station pile foundation, realizes enclosure foundation pit engineering and underground station structure intensive sharing, solves later period enclosure stake waste problem, effectively improves resource utilization efficiency, simultaneously reduces underground station structure outer wall thickness and reinforcement, saves engineering investment.

Description

Technical Field

[0001] This utility model belongs to the field of underground engineering, and in particular relates to a recyclable structure for foundation pit retaining pile foundations. Background Technology

[0002] In the field of rail transit engineering, the foundation pit support for underground stations such as subways, maglev trains, and light rails is a key technology for underground space development, directly affecting the safety and economy of the project. Among them, the retaining pile support system has become one of the main support forms for underground stations due to its good load-bearing capacity, adaptability, and ease of construction. This technology forms a rigid or semi-rigid support barrier by setting up reinforced concrete cast-in-place pile structures around the foundation pit, combined with internal bracing or anchor systems, effectively resisting soil lateral pressure, groundwater seepage, and surrounding loads, ensuring the safety of foundation pit excavation and underground station structure construction.

[0003] Although the retaining pile support system is widely used, its life-cycle performance and resource utilization efficiency still have significant defects, most notably the waste of the support structure after its service life ends. Specifically: functional failure and structural redundancy: As a temporary support structure, the design service life of retaining piles is usually 2-3 years (matching the construction cycle of the main structure). However, in actual projects, due to factors such as extended construction cycles and adjustments to rail transit network planning, some retaining piles are left idle for a long time after completing their support function. Their bearing capacity and material properties cannot be reused in subsequent projects, resulting in permanent structural redundancy.

[0004] The problems of "high temporariness and high abandonment rate" in traditional retaining pile support technology urgently need to be solved. Developing a new type of recyclable retaining pile system has become a key direction for breaking through the industry bottleneck. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the deficiencies and defects mentioned in the background art above, and to provide a composite structure of underground station pile-wall, so as to realize the intensive sharing of the retaining foundation pit project and the underground station structure, solve the problem of waste of retaining piles in the later stage, effectively improve resource utilization efficiency, and at the same time reduce the thickness and reinforcement of the outer wall of the underground station structure, thus saving project investment.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this utility model is as follows:

[0007] A composite pile-wall structure for an underground station includes an underground station structure (such as a subway, maglev, or light rail) and foundation pit retaining piles disposed on the outside of the underground station structure. Side wall bottom support beams are provided on both sides of the underground station structure. Transverse reserved steel bars are provided in the foundation pit retaining piles. First connecting steel bars are provided in the side wall bottom support beams. A steel bar connection assembly for connecting the transverse reserved steel bars and the first connecting steel bars is provided on the side of the foundation pit retaining piles closest to the underground station structure.

[0008] In the aforementioned underground station pile-wall composite structure, preferably, the retaining piles of the foundation pit are further provided with a reserved steel pipe, and the bottom support beam of the side wall is also provided with a corresponding second connecting steel bar. The second connecting steel bar is fixedly connected to the inner cavity of the reserved steel pipe, and the reserved steel pipe is filled with post-cast concrete integrally cast with the bottom support beam of the side wall. The embedded steel pipe can be precisely fixed by positioning brackets during pre-embedding, and the outer wall of the steel pipe can be strengthened with the bonding force with the concrete interface by welding studs and other measures, reducing the impact of construction errors on the connection performance. Adding a pre-embedded steel pipe has at least the following advantages: 1. The pre-embedded steel pipe and the internal filling concrete form a steel pipe concrete composite structure. The steel pipe exerts a restraining effect on the concrete, significantly improving the compressive strength and ductility of the concrete; at the same time, the pre-embedded steel pipe itself can bear axial force, bending moment and shear force, forming a collaborative force-bearing system of "steel pipe-concrete-reinforcement" together with the transverse reserved steel bars. 2. Concrete-filled steel tubing has a higher compressive bearing capacity than reinforced concrete of the same cross-section, making it particularly suitable for high-load conditions where retaining piles also serve as foundation piles (such as the vertical loads on the main structure of a station). 3. The embedded steel pipes have greater stiffness, effectively transmitting horizontal forces (such as earth pressure and seismic forces), resulting in stronger integrity and resistance to deformation at the joint, making it less prone to failure due to localized stress concentration. 4. Concrete-filled steel tubing exhibits better ductility than pure reinforced concrete. Under dynamic loads such as earthquakes and uneven settlement, the joint is less prone to brittle failure, meeting the seismic requirement of "not collapsing under major earthquakes." 5. As a rigid support, the embedded steel pipes effectively control the deformation of the joint, preventing crack propagation due to relative displacement between the side wall support beam and the retaining piles, making it particularly suitable for soft soil layers or high-water areas (reducing the risk of leakage). 6. After the embedded steel pipes are filled with concrete, the joint forms a three-dimensional constraint system. Even if there are defects in the local reinforcement connections, the steel pipes and concrete can still bear part of the load, exhibiting "redundant load-bearing" characteristics.

[0009] In the aforementioned underground station pile-wall composite structure, preferably, the foundation pit retaining piles include multiple bored cast-in-place piles arranged at intervals, with jet grouting piles provided between adjacent bored cast-in-place piles, the bored cast-in-place piles and the jet grouting piles overlapping each other, both the bored cast-in-place piles and the jet grouting piles being cylindrical, and the surfaces formed by the center lines of the bored cast-in-place piles and the jet grouting piles being parallel to each other.

[0010] In the aforementioned underground station pile-wall composite structure, preferably, the diameter of the bored cast-in-place pile is larger than the diameter of the jet grouting pile, wherein the diameter of the bored cast-in-place pile is 0.8-1.2 meters and the diameter of the jet grouting pile is 0.5-0.9 meters.

[0011] In the aforementioned underground station pile-wall composite structure, preferably, each of the drilled cast-in-place piles is provided with transverse reserved reinforcing bars and reinforcing bar connection components, and each of the drilled cast-in-place piles is provided with a reserved steel pipe at its center. Each of the drilled cast-in-place piles is connected to the side wall bottom support beam through the transverse reserved reinforcing bars, reinforcing bar connection components and first connecting reinforcing bars, and each of the drilled cast-in-place piles is also connected to the side wall bottom support beam through the reserved steel pipe, second connecting reinforcing bars and post-poured concrete.

[0012] In the aforementioned underground station pile-wall composite structure, preferably, the bored pile has multiple layers of transverse reserved steel bars of different heights, with multiple transverse reserved steel bars arranged side by side in each layer; the side wall bottom support beam has correspondingly multiple layers of first connecting steel bars of different heights, with multiple first connecting steel bars also arranged side by side in each layer; each transverse reserved steel bar and the first connecting steel bar are connected by the steel bar connecting assembly; the bored pile has double layers of reserved steel pipes, with one reserved steel pipe in each layer at the center of the bored pile; the side wall bottom support beam has correspondingly double layers of second connecting steel bars of different heights, with each second connecting steel bar welded to the reserved steel pipe.

[0013] In the aforementioned underground station pile-wall composite structure, preferably, the joints between the bored piles and the underground station structure and the bottom support beam of the side wall are all provided with roughened surfaces.

[0014] In the aforementioned underground station pile-wall composite structure, preferably, the bottom surfaces of the bored piles and the jet grouting piles extend into the underground station structure at a distance greater than 3 meters below the bottom surface.

[0015] In the aforementioned underground station pile-wall composite structure, preferably, the width of the side wall bottom support beam is 1-1.5 meters and the height is 1-1.5 meters, and the underground station structure and the side wall bottom support beam are integrally formed.

[0016] In the aforementioned underground station pile-wall composite structure, preferably, the diameters of the transverse reserved reinforcing bars and the first connecting reinforcing bars are the same, both being C25-C32; the reinforcing bar connection assembly is a Class I straight thread sleeve; the reserved steel pipe is a Q355 seamless round steel pipe with a diameter of DN250-DN400. The diameter of the Class I straight thread sleeve is the same as the diameter of the transverse reserved reinforcing bars.

[0017] The construction method of the underground station pile-wall composite structure of this utility model may include the following steps:

[0018] S1: Construct foundation pit retaining piles according to the construction requirements of the underground station structure, and reserve Class I straight threaded sleeves, transverse reserved steel bars and reserved steel pipes within the range of the retaining piles below the bottom of the underground station structure.

[0019] S2: Before the construction of the underground station structure, the surface of the retaining pile is roughened. The first connecting steel bar on the outside of the reserved steel pipe is connected through the Class I straight thread sleeve and the transverse reserved steel bar reserved in the retaining pile. The second connecting steel bar on the inside of the reserved steel pipe is welded to the reserved steel pipe and extends into the bored pile.

[0020] S3: An underground station structure is set inside the retaining piles, and a side wall bottom support beam is set at the bottom of the structure. The side wall bottom support beam is implemented at the same time as the bottom slab of the underground station structure, and concrete of the same grade as the side wall bottom support beam is poured in the reserved steel pipe at the same time to form a structural whole.

[0021] The foundation pit retaining piles include bored cast-in-place piles and jet grouting piles. Both bored cast-in-place piles and jet grouting piles are cylindrical, with the diameter of the bored cast-in-place piles being larger than that of the jet grouting piles. The bottom surfaces of both bored cast-in-place piles and jet grouting piles extend into the bottom of the underground station's main structure by more than 3 meters.

[0022] Compared with the prior art, the advantages of this utility model are:

[0023] This utility model discloses a composite pile-wall structure for underground stations. It effectively connects the retaining piles (specifically, bored piles) to the bottom support beams of the side walls at the base of the underground station structure using reinforcing steel (preferably also including circular steel pipes), thus forming the pile foundation for the underground station. This allows the retaining piles to simultaneously serve as the pile foundation for the underground station structure, achieving structural integration and sharing between the retaining piles and the underground station structure. It also solves the problem of wasted retaining piles later on, effectively improving resource utilization efficiency. Furthermore, it reduces the thickness and reinforcement of the outer walls of the underground station structure, saving project investment and urban space resources. This composite structure has advantages such as simple structure, good performance, and ease of promotion and application. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the underground station pile-wall composite structure of this utility model.

[0026] Figure 2This is an enlarged schematic diagram of the connection between the side wall bottom support beam and the bored pile in the underground station pile-wall composite structure of this utility model.

[0027] Figure 3 for Figure 2 Top view.

[0028] Legend

[0029] 1. Drilled cast-in-place piles; 2. Horizontal reserved reinforcing bars; 3. Reinforcing bar connection components; 41. First connecting reinforcing bars; 42. Second connecting reinforcing bars; 5. Side wall bottom support beams; 6. Underground station structure; 7. Reserved steel pipes; 8. Vertical reinforcing bars of piles; 9. Jet grouting piles. Detailed Implementation

[0030] To facilitate understanding of this utility model, it will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of this utility model is not limited to the following specific embodiments.

[0031] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0032] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of protection of this invention.

[0033] Example:

[0034] like Figures 1-3 As shown, the underground station pile-wall composite structure of this embodiment includes an underground station structure 6 and foundation pit retaining piles set on the outside of the underground station structure 6. The foundation pit retaining piles include bored cast-in-place piles 1 and jet grouting piles 9. Side wall bottom support beams 5 are provided on both sides of the underground station structure 6, and the side wall bottom support beams 5 and the underground station structure 6 are cast together to form an integral structure (that is, the underground station structure 6 and the side wall bottom support beams 5 are integrally formed structures). The side wall bottom support beams 5 are connected to each bored cast-in-place pile 1. The wall is equipped with a Class I straight threaded sleeve (i.e., the rebar connection assembly 3), a transverse reserved rebar 2, and a reserved steel pipe 7. The side wall bottom support beam 5 is provided with a first connecting rebar 41 and a second connecting rebar 42. The first connecting rebar 41 on the outside of the reserved steel pipe 7 is connected to the transverse reserved rebar 2 through the Class I straight threaded sleeve after the foundation pit is excavated. The second connecting rebar 42 on the inside of the reserved steel pipe 7 extends into the inside of the bored pile 1 after the foundation pit is excavated, and concrete of the same level as the side wall bottom support beam 5 is poured into the reserved steel pipe 7 at the same time.

[0035] In this embodiment, the underground station pile-wall composite structure effectively connects the bored piles 1 with the side wall bottom support beams 5 set at the bottom of the underground station structure 6, thus forming the pile foundation of the underground station structure 6. This allows the foundation pit retaining pile foundation to also serve as the pile foundation structure of the underground station structure 6, achieving structural intensive sharing between the foundation pit retaining structure and the underground station structure 6. This solves the problem of waste of retaining piles in the later stage, effectively improves resource utilization efficiency, and reduces the thickness and reinforcement of the outer wall of the underground station structure 6, saving project investment and urban space resources.

[0036] like Figure 2 , Figure 3 As shown in this embodiment, in order to ensure the stability of the side wall bottom support beam 5, each bored pile 1 is provided with a transverse reserved steel bar 2 and a steel bar connection component 3, and each bored pile 1 is provided with a reserved steel pipe 7 at its center (avoiding the vertical steel bar 8 in the bored pile 1). Each bored pile 1 is connected to the side wall bottom support beam 5 through the transverse reserved steel bar 2, the steel bar connection component 3 and the first connecting steel bar 41, and each bored pile 1 is also connected to the side wall bottom support beam 5 through the reserved steel pipe 7, the second connecting steel bar 42 and the post-poured concrete. Specifically, the bored pile 1 has multiple layers of transverse reserved steel bars 2 of different heights, with multiple transverse reserved steel bars 2 arranged side by side in each layer. The side wall bottom support beam 5 has multiple layers of first connecting steel bars 41 of different heights, with multiple first connecting steel bars 41 arranged side by side in each layer. Each transverse reserved steel bar 2 and the first connecting steel bar 41 are connected by steel bar connecting components 3. The bored pile 1 has double layers of reserved steel pipes 7, with one reserved steel pipe 7 at the center of the bored pile 1. The side wall bottom support beam 5 has double layers of second connecting steel bars 42 of different heights, with each second connecting steel bar 42 welded to the reserved steel pipe 7.

[0037] In this embodiment, a jet grouting pile 9 is provided between two adjacent bored piles 1, and the bored piles 1 and the jet grouting piles 9 overlap, thereby ensuring the stability, strength, and waterproofing of the foundation pit retaining pile structure. At the same time, the surfaces formed by the center lines of the bored piles 1 and the jet grouting piles 9 are parallel to each other, facilitating construction.

[0038] In this embodiment, both the bored pile 1 and the jet grouting pile 9 are cylindrical, and the diameter of the bored pile 1 is larger than that of the jet grouting pile 9. Simultaneously, the diameter and length of the bored pile 1 and the jet grouting pile 9, the dimensions of the side wall bottom support beam 5, and the transverse reserved reinforcing bars 2 must also meet the requirements of the foundation pit design and structural safety design. For example, the diameter of the bored pile 1 is 0.8-1.2 meters, preferably 1.2 meters; the diameter of the jet grouting pile 9 is 0.5-0.9 meters, preferably 0.8 meters. The width of the side wall bottom support beam 5 is 1-1.5 meters, and the height is 1-1.5 meters, preferably 1 meter; the diameter of the transverse reserved reinforcing bars 2 is C25-C32, preferably C28; the reserved steel pipe 7 is a Q355 seamless round steel pipe with a diameter of DN250-DN400, preferably DN300; the diameter of the Class I straight threaded sleeve is the same as the diameter of the transverse reserved reinforcing bars 2; the diameter of the connecting reinforcing bars 4 is the same as the diameter of the transverse reserved reinforcing bars 2.

[0039] Meanwhile, to ensure structural safety, the bottom surfaces of both bored pile 1 and jet grouting pile 9 extend below the bottom of the underground station structure 6. Specifically, the bottom surfaces of bored pile 1 and jet grouting pile 9 extend longitudinally more than 3 meters into the bottom surface of the underground station structure 6. In addition, geological conditions, load stress, and other factors must be comprehensively considered to ensure structural safety.

[0040] In this embodiment, the joints between the bored pile 1, the underground station structure 6, and the side wall bottom support beam 5 are all provided with roughened surfaces.

[0041] It should be noted that the diameters and lengths of the various piles mentioned above are only commonly used numerical ranges. However, due to the various special environments encountered during actual construction, the specific diameters and lengths of various piles are determined based on their stress, burial depth, and geological conditions, and may therefore not fall within the above numerical ranges.

[0042] To better understand the above scheme, this embodiment also provides a construction method for an underground station pile-wall composite structure, including the following steps:

[0043] The foundation pit retaining piles are constructed according to the construction requirements of underground station structure 6. The foundation pit retaining piles include bored piles 1 and jet grouting piles 9. Both bored piles 1 and jet grouting piles 9 are cylindrical, with the diameter of bored pile 1 being larger than that of jet grouting pile 9. The diameter and length of bored piles 1 and jet grouting piles 9 must meet the design requirements for the foundation pit retaining piles and the pile foundation of underground station structure 6. A Class I straight threaded sleeve, transverse reinforcing bars 2, and steel pipe 7 are pre-reserved within the range of the corresponding bored piles 1 below the bottom of underground station structure 6. The type of transverse reinforcing bars 2 and steel pipe 7 must meet the foundation pit design requirements and structural safety design requirements. The bottom surfaces of bored piles 1 and jet grouting piles 9 extend more than 3 meters below the bottom of underground station structure 6. Furthermore, geological conditions, load stress, and other factors must be comprehensively considered to ensure structural safety.

[0044] During the construction of the side wall bottom support beam 5, the surface of the bored pile 1 is first roughened. The first connecting steel bar 41 on the outside of the reserved steel pipe 7 is connected to the Class I straight threaded sleeve and the transverse reserved steel bar 2 reserved on the bored pile 1. The second connecting steel bar 42 on the inside of the reserved steel pipe 7 extends into the bored pile 1 and is welded to the inner cavity of the reserved steel pipe 7. Concrete of the same grade as the side wall bottom support beam 5 is poured into the reserved steel pipe 7 to form a whole.

[0045] An underground station structure 6 is installed inside the retaining piles of the foundation pit, and a side wall bottom support beam 5 is installed below its side wall. The two are formed as a whole by pouring concrete. The dimensions and installation of the side wall bottom support beam 5 must meet the structural safety design requirements.

[0046] The composite structure constructed using the above-mentioned construction method, which combines the foundation pit retaining pile foundation with the underground station pile foundation, allows the foundation pit retaining pile foundation to simultaneously serve as the pile foundation for the underground station structure 6. This achieves structural intensive sharing between the foundation pit retaining structure and the underground station structure 6, solves the problem of waste of retaining piles in the later stage, effectively improves resource utilization efficiency, and reduces the thickness and reinforcement of the outer wall of the underground station structure 6 (since the foundation pit retaining structure bears vertical and horizontal loads, the stress on the outer wall is reduced, thus the thickness and reinforcement of the outer wall can be reduced), saving project investment and urban space resources.

[0047] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A composite structure of pile walls for an underground railway station, characterized in that, The structure includes an underground station structure (6) and foundation pit retaining piles located outside the underground station structure (6). Side wall bottom support beams (5) are provided on both sides of the underground station structure (6). The foundation pit retaining piles are provided with transverse reserved steel bars (2). The side wall bottom support beams (5) are provided with corresponding first connecting steel bars (41). The foundation pit retaining piles are provided with steel bar connection components (3) for connecting the transverse reserved steel bars (2) and the first connecting steel bars (41) on the side close to the underground station structure (6).

2. The underground station pile-wall composite structure according to claim 1, characterized in that, The foundation pit retaining piles are also provided with reserved steel pipes (7), and the side wall bottom support beam (5) is also provided with corresponding second connecting steel bars (42). The second connecting steel bars (42) and the inner cavity of the reserved steel pipe (7) are fixedly connected. The reserved steel pipe (7) is filled with post-cast concrete that is integrally cast with the side wall bottom support beam (5).

3. The underground station pile-wall composite structure according to claim 2, characterized in that, The foundation pit retaining piles include multiple bored cast-in-place piles (1) arranged at intervals, and jet grouting piles (9) are provided between adjacent bored cast-in-place piles (1). The bored cast-in-place piles (1) and the jet grouting piles (9) are connected to each other. Both the bored cast-in-place piles (1) and the jet grouting piles (9) are cylinders. The surface formed by the center lines of the bored cast-in-place piles (1) and the surface formed by the center lines of the jet grouting piles (9) are parallel to each other.

4. The underground station pile-wall composite structure according to claim 3, characterized in that, The diameter of the bored pile (1) is larger than the diameter of the jet grouting pile (9). The diameter of the bored pile (1) is 0.8-1.2 meters, and the diameter of the jet grouting pile (9) is 0.5-0.9 meters.

5. The underground station pile-wall composite structure according to claim 3, characterized in that, Each of the drilled piles (1) is provided with a transverse reserved steel bar (2) and a steel bar connection assembly (3), and each of the drilled piles (1) is provided with a reserved steel pipe (7) at the center. Each of the drilled piles (1) is connected to the side wall bottom support beam (5) through the transverse reserved steel bar (2), the steel bar connection assembly (3) and the first connecting steel bar (41), and each of the drilled piles (1) is also connected to the side wall bottom support beam (5) through the reserved steel pipe (7), the second connecting steel bar (42) and the post-poured concrete.

6. The underground station pile-wall composite structure according to claim 4, characterized in that, The bored pile (1) is provided with multiple layers of transverse reserved steel bars (2) of different heights. Multiple transverse reserved steel bars (2) are arranged side by side in each layer. The side wall bottom support beam (5) is provided with multiple layers of first connecting steel bars (41) of different heights. Multiple first connecting steel bars (41) are also arranged side by side in each layer. Each transverse reserved steel bar (2) and the first connecting steel bar (41) are connected by the steel bar connecting assembly (3). The bored pile (1) is provided with double-layer reserved steel pipes (7). Each layer of reserved steel pipes (7) is located at the center of the bored pile (1). The side wall bottom support beam (5) is provided with double-layer second connecting steel bars (42) of different heights. Each second connecting steel bar (42) is welded to the reserved steel pipe (7).

7. The underground station pile-wall composite structure according to claim 3, characterized in that, The joints between the bored pile (1), the underground station structure (6), and the side wall bottom support beam (5) are all provided with roughened surfaces.

8. The underground station pile-wall composite structure according to claim 3, characterized in that, The bottom surfaces of the bored piles (1) and the jet grouting piles (9) extend into the underground station structure (6) at a distance greater than 3 meters below the bottom surface.

9. The underground station pile-wall composite structure according to any one of claims 1-8, characterized in that, The width of the side wall bottom support beam (5) is 1-1.5 meters and the height is 1-1.5 meters. The underground station structure (6) and the side wall bottom support beam (5) are integrally formed structures.

10. The underground station pile-wall composite structure according to any one of claims 2-9, characterized in that, The diameter of the transverse reserved steel bar (2) and the first connecting steel bar (41) is the same, both being C25-C32; the steel bar connection assembly (3) is a Class I straight thread sleeve; the reserved steel pipe (7) is a Q355 seamless round steel pipe with a diameter of DN250-DN400.

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