A tunnel structure constructed by open cut method and a construction method thereof

Abstract

The application relates to the technical field of tunnel construction, in particular to a open-cut tunnel structure which comprises a bottom plate poured at the bottom of a foundation pit and side walls arranged at the two sides of the bottom plate, a top plate connected to the top of the side walls, a plurality of reinforcing members arranged at the outer sides of each side wall at intervals, the reinforcing members on each side being linearly and equidistantly distributed along the longitudinal direction of the side wall, and the reinforcing members corresponding to the two sides being a group; a plurality of load lever members are horizontally arranged at equal intervals above the top plate, each load lever member is matched with the reinforcing members of the corresponding group, and the matched load lever members and the reinforcing members are connected through fulcrum lever members. The open-cut tunnel structure can convert the vertical load into horizontal load through the mutual cooperation of the load lever members and the fulcrum lever members, and transmit the horizontal load to the lateral load transmission area, so that the design load of the top plate structure can be reduced and the local stress concentration problem of the side wall can be solved under the premise of ensuring the safety of the structure.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to an open-cut tunnel structure and its construction method. Background Technology

[0002] In recent years, with the rapid growth of my country's economy, the country's annual investment in infrastructure has been enormous and is gradually increasing. Furthermore, with the continuous growth of the population, surface transportation is no longer sufficient to meet people's daily travel needs, leading to the continuous development of underground transportation lines in my country, including in loess regions. Current research indicates that cities such as Xi'an, Lanzhou, and Luoyang, located in loess regions, have planned multiple underground transportation lines. The mileage of loess tunnels is rapidly increasing, and planned subway lines all traverse loess strata to varying degrees, with many sections located below the groundwater level. In the field of geotechnical engineering, the widespread distribution of soft loess foundations in loess regions presents unique challenges to related excavation and backfilling projects due to their special engineering properties.

[0003] Loess soft foundation refers to a foundation composed of loess, which has weak engineering properties and is prone to deformation and failure. Construction activities such as excavation and backfilling disturb the loess soft foundation, leading to deformation and stability issues. During the excavation and backfilling process of open-cut tunnels in loess geology, the soil undergoes unloading and loading processes, resulting in deformation rebound and recompression deformation. The deformation mechanism of the tunnel foundation is not yet clear, and there is currently no readily available method for calculating the stress of tunnel lining. Furthermore, factors such as groundwater and variations in geological conditions further complicate the soil deformation and lining stress mechanisms. Therefore, it is necessary to study the deformation mechanism of loess soft foundation under excavation-backfilling load disturbance and propose corresponding treatment technologies for foundation hazards, providing suggestions and support for construction safety. The research results can also serve as a reference for similar projects in the region.

[0004] In-depth research on the deformation patterns of loess soft soil foundations under excavation-backfilling load disturbance has significant theoretical and practical value for improving the safety, reliability, and economic benefits of loess soft soil foundation engineering. Firstly, in-depth research can provide more reasonable guidance for engineering design in loess areas, reducing the risk of soft soil foundation deformation. Secondly, a thorough understanding of the deformation mechanism of loess soft soil foundations helps improve the quality of engineering construction and ensure the long-term stability of infrastructure. Finally, it can effectively alleviate problems such as uneven settlement, roof deflection, and structural cracking caused by backfilling disturbance in loess areas, effectively solving the deformation problem of loess soft soil foundations, reducing engineering maintenance costs, improving the economic benefits of the project, and lowering the costs of later-stage disease treatment and operation and maintenance, resulting in better life-cycle economics. Summary of the Invention

[0005] To address the challenges of excavation-backfill load disturbance during construction, this invention aims to develop a novel open-cut tunnel structure and construction method that combines high strength, high durability and stability, and low construction disturbance. During tunnel backfilling, the weight of the backfill soil and additional loads act on load lever members, causing the lever members to rotate slightly around the fulcrum lever member. Through the lever arm relationship, a portion of the vertical load is converted into a horizontal component force via a concrete foundation and transferred to the soil on both sides, thus significantly reducing the vertical pressure on the roof slab. Furthermore, by arranging several sets of "load lever member-fulcrum lever member units" at intervals along the tunnel axis in the longitudinal direction of the tunnel, and connecting these units with limiting and reinforcing connectors to form a continuously cooperating force system, the backfill load of the entire open-cut tunnel is dispersed, transferred, and homogenized.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: This application provides an open-cut tunnel structure, including a bottom slab cast at the bottom of the foundation pit and side walls set on both sides of the bottom slab. A top slab is connected to the top of the side walls. Multiple reinforcing members are spaced apart on the outer side of each side wall. The reinforcing members on each side are linearly and equidistantly distributed along the longitudinal direction of the side wall, and the corresponding reinforcing members on both sides form a group. Multiple load lever members are arranged horizontally at equal intervals above the top slab. Each load lever member cooperates with the corresponding group of reinforcing members, and the cooperating load lever members and the reinforcing members are connected by fulcrum lever members.

[0007] Furthermore, in the technical solution, a limiting connector and a reinforcing connector are provided between two adjacent reinforcing members on the same side, with the limiting connector located above the reinforcing connector.

[0008] Furthermore, the technical solution includes multiple high-pressure jet grouting piles arranged on the outside of the side wall, with a concrete foundation poured on top of each high-pressure jet grouting pile and an enlarged pile head at the bottom of each high-pressure jet grouting pile.

[0009] Furthermore, the load lever member is a rod with a T-shaped or L-shaped cross-section, and the inclination angle of the load lever member is 5° to 30°.

[0010] Furthermore, the technical solution includes a fulcrum lever component and ball joint supports and composite hinge supports disposed at both ends of the fulcrum lever. The ball joint supports are connected to the load lever component, and the composite hinge supports are connected to the concrete foundation.

[0011] Specifically, the composite hinge support includes a hinge ear plate, an eccentric connecting block, a multi-hole position adjusting plate, a hinge shaft, and a limiting component; one side of the hinge ear plate is connected to the concrete foundation, and the other side is connected to the eccentric connecting block, the multi-hole position adjusting plate is connected to the eccentric connecting block, one end of the hinge shaft passes through the center hole of the multi-hole position adjusting plate, the other end is connected to the fulcrum lever, and a limiting component is provided near the multi-hole position adjusting plate on the hinge shaft.

[0012] In a further step of the technical solution, the limiting connector includes concrete segments symmetrically arranged on adjacent concrete piers, a connecting rib between the two concrete segments, and a stop block and a rubber pad inside the concrete segments, with the end of the connecting rib abutting against the rubber pad.

[0013] Furthermore, the technical solution includes a connecting anchor rod pre-embedded in each high-pressure jet grouting pile, a first reinforced concrete connecting beam poured on the top of the connecting anchor rod, and a second reinforced concrete connecting beam provided between two adjacent first reinforced concrete connecting beams, with multiple pile-to-pile reinforcement bodies provided on the second reinforced concrete connecting beam.

[0014] Furthermore, in the technical solution, a load-reducing layer with a thickness of 10-20cm is laid between the load lever component and the top plate.

[0015] A further technical solution includes a construction method for an open-cut tunnel structure, comprising the following steps: Step 1: Pour the bottom slab at the bottom of the foundation pit and construct the side walls on both sides of the foundation pit. Arrange high-pressure jet grouting piles outside the side walls and pour a concrete pile cap on top of the high-pressure jet grouting piles. Step 2: Determine the extent of the load transfer zone on the outside of the side wall, and perform layered compaction treatment on the lateral load transfer zone; Step 3: Install the top plate and the fulcrum lever component, and connect the fulcrum lever component to the concrete foundation through a composite hinge support to ensure that the fulcrum lever component can rotate smoothly under load. Step 4: Install a load lever component above the top plate, and connect the load lever component to the fulcrum lever component through a ball joint support; Step 5: Evenly lay a load-reducing layer between the load-bearing lever member and the top slab; Step 6: Select soil with good compaction properties for backfilling in layers, with each layer controlled at a thickness of 20-40cm. During backfilling, each layer of soil should be fully compacted. During the backfilling process, the load lever component is gradually loaded by the pressure of the backfill soil, resulting in rotation and slight settlement, gradually converting the vertical load into a horizontal load, and transferring it to the lateral load transfer zone through the fulcrum lever component.

[0016] Compared with the prior art, the beneficial effects of the present invention are: In traditional backfilling methods, the weight of all backfill soil acts directly on the tunnel roof, causing it to be under long-term pressure and stress concentration. This invention utilizes the cooperation of load lever components and fulcrum lever components to convert vertical loads into horizontal loads and transfer them to the lateral load transfer zone. This significantly reduces the vertical stress on the roof, allowing for a suitable reduction in roof thickness and the amount of concrete and steel reinforcement used, thus achieving better structural economy.

[0017] Traditional backfilling methods, where the top slab is directly subjected to pressure, can easily lead to localized settlement or deformation. The fulcrum lever component of this invention can transfer and disperse the load generated during the backfilling process in stages, thereby reducing the problems of uneven settlement, top slab deflection, and sidewall cracking that occur in tunnel structures after backfilling.

[0018] This invention enables the adjustment of the fulcrum lever angle through ball joint support and composite hinge support. The multi-fulcrum flexible support can adapt to different backfill heights, different overburden loads, and different geological conditions, thus facilitating its application in multiple scenarios.

[0019] This invention achieves graded adjustment of the eccentric position by axially constraining the hinge shaft under normal operating conditions through a limiting component, while maintaining a constant vertical load on the backfill soil. During eccentric adjustment, the limiting component is disassembled, releasing the hinge shaft from its original hole position. The multi-hole adjustment disc is then rotated to the target position, and finally the hinge shaft is reinserted into the new hole and relocked. This alters the rotational torque generated by the load lever component, thereby adjusting the proportion of vertical load converted into horizontal reaction force, allowing the structural stress state to adapt to different backfill heights and geological conditions.

[0020] This invention enables limited relative deformation of adjacent cross sections during backfilling construction by setting limiting connectors and reinforcing connectors between reinforcing components. This avoids the concentration of longitudinal structural internal forces caused by inconsistent force adjustment of load lever components, increases the stability between concrete foundations, and ensures the longitudinal integrity and stability of the tunnel structure. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Right view of the middle section structure; Figure 3 This is a schematic diagram of the ball joint support structure of the present invention; Figure 4 This is an exploded view of the composite hinge support portion of the present invention; Figure 5 For the present invention Figure 4 Mid-section structural assembly diagram; Figure 6 This is a schematic diagram of the composite hinge support structure of the present invention; Figure 7 This is a schematic diagram of the limiting connector structure of the present invention; Figure 8 This is a perspective view of the overall structure of the present invention; In the diagram: 1. Base plate; 2. Side wall; 3. Top plate; 4. Reinforcing component; 41. High-pressure jet grouting pile; 42. Concrete cap; 43. Pile enlarged head; 5. Load lever component; 6. Fulcrum lever component; 61. Fulcrum lever; 62. Spherical hinge support; 621. Upper support plate; 622. Stainless steel sliding plate; 623. Steel ball core sphere; 624. Lower spherical shell; 625. Lower support plate; 63. Composite hinge support; 6 31. Hinge ear plate; 632. Eccentric connecting block; 633. Multi-hole position adjustment disc; 634. Hinge shaft; 635. Limiting component; 7. Limiting connector; 71. Concrete segment; 72. Connecting rib; 73. Stop block; 74. Rubber pad; 8. Reinforcing connector; 81. Connecting anchor; 82. First reinforced concrete connecting beam; 83. Second reinforced concrete connecting beam; 84. Pile reinforcement body; 9. Load reduction layer. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "upper end", "lower end", "front end", "rear end", "left end", "right end", "inner side", "outer side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] In traditional open-cut backfilling methods, the weight of all backfill soil acts directly on the tunnel roof, causing the roof to be under long-term pressure and stress concentration. Direct pressure can easily lead to local subsidence or deformation of the roof, as well as uneven settlement, roof deflection, and sidewall cracking in the tunnel structure after backfilling.

[0027] Based on the above problems, this application provides an open-cut tunnel structure that converts vertical loads into horizontal loads through a load lever member installed above the top slab in cooperation with a fulcrum lever member, and then transfers the loads to the lateral load transfer zone through the fulcrum.

[0028] Example 1 Reference Figures 1-8 As shown, this application provides an open-cut tunnel structure, including a bottom slab 1 cast at the bottom of the foundation pit and side walls 2 set on both sides of the bottom slab 1. The top of the side walls 2 is connected to a top slab 3. Each side wall 2 has multiple reinforcing members 4 spaced apart on its outer side. The reinforcing members 4 on each side are linearly and equidistantly distributed along the longitudinal direction of the side wall 2, and the corresponding reinforcing members 4 on both sides form a group. Multiple load lever members 5 are arranged horizontally at equal intervals above the top slab 3. Each load lever member 5 cooperates with the corresponding group of reinforcing members 4, and the cooperating load lever members 5 and the reinforcing members 4 are connected by fulcrum lever members 6.

[0029] Preferably, adjacent load lever components 5 are connected by a set of connecting rods, which are rod structures located on both sides of the load lever components 5. This allows multiple load lever components 5 to form an integrated force-bearing system.

[0030] In this embodiment, the sidewall 2 is constructed with a structure that provides good waterproofing and compressive strength to ensure the safety of the tunnel. As an example: The primary lining consists of shotcrete (C25) + steel mesh + steel arch frame, which mainly bears the pressure of the surrounding rock and resists the initial water pressure; the waterproof isolation layer consists of ECB / EVA / PVC waterproof board (1.5~2.0mm thick) and a non-woven fabric buffer layer; the secondary lining consists of cast-in-place waterproof concrete (C35 / P10), which bears the final water pressure and ensures long-term waterproofing.

[0031] In detail, the top slab 3 is constructed using reinforced concrete to ensure its strength meets design requirements. The construction of the top slab 3 is closely connected to the side wall 2. Before pouring the top slab 3, the concrete surface at the top of the side wall 2 that contacts the top slab 3 is roughened to remove laitance and loose particles, and is thoroughly moistened to ensure good bonding between the old and new concrete.

[0032] In this embodiment, the reinforcing member 4 includes a plurality of high-pressure jet grouting piles 41 arranged on the outside of the side wall 2. A concrete foundation 42 is poured on the top of the high-pressure jet grouting piles 41, and an enlarged pile head 43 is provided at the bottom of the high-pressure jet grouting piles 41.

[0033] Specifically, multiple high-pressure jet grouting piles 41 are arranged in a cuboid structure. The pile enlarged head 43 increases the bearing area at the pile end, improves the pull-out resistance and end-bearing capacity, and prevents the pile body from settling or becoming unstable.

[0034] As an example, the load lever member 5 is a rod with a T-shaped or L-shaped cross section. The load lever member 5 can be made of reinforced concrete, steel structure or steel-concrete composite materials, and the inclination angle of the load lever member 5 is 5° to 30°.

[0035] In this embodiment, the fulcrum lever member 6 includes a fulcrum lever 61 and ball joint supports 62 and composite hinge supports 63 disposed at both ends of the fulcrum lever 61. The ball joint supports 62 are connected to the load lever member 5, and the composite hinge supports 63 are connected to the concrete foundation 42.

[0036] In detail, the fulcrum lever 61 is a rod structure.

[0037] For more details, see [link / reference] Figure 3 As shown, the ball joint support 62 consists of an upper support plate 621, a stainless steel sliding plate 622, a steel ball core 623, a lower spherical shell 624, and a lower support plate 625. The upper support plate 621 is connected to the fulcrum lever 61 by bolts, responsible for transmitting the upper load downwards. The lower support plate 625 is connected to the load lever component 5 by bolts. The lower spherical shell 624 has a concave spherical structure. The surface of the steel ball core 623 is a PTFE sliding plate, which contacts the surface of the stainless steel sliding plate 622. This contact is a spherical contact, providing an extremely low coefficient of friction (≤0.03), forming a low-friction surface, ensuring flexible and smooth rotation and sliding. The steel ball core 623, the stainless steel sliding plate 622, and the lower spherical shell 624 are precisely matched to achieve 360° rotation in any direction, releasing the internal stress generated by temperature and load in the structure.

[0038] For details, refer to Figures 4-6 As shown, the composite hinge support 63 includes a hinge ear plate 631, an eccentric connecting block 632, a multi-hole position adjustment plate 633, a hinge shaft 634, and a limiting component 635. One side of the hinged ear plate 631 is fixedly connected to the concrete foundation 42, and the other side is rigidly connected to an eccentric connecting block 632 by bolts. A multi-hole position adjustment plate 633 is connected to the eccentric connecting block 632. The multi-hole position adjustment plate 633 is attached to the eccentric connecting block 632 and connected by bolts. One end of the hinge shaft 634 passes through the center hole of the multi-hole position adjustment plate 633, and the other end is connected to the fulcrum lever 61. A limit component 635 is provided on the hinge shaft 634 near the multi-hole position adjustment plate 633.

[0039] It should be noted that the limiting component 635 consists of a locking nut and a washer. The washer abuts against the multi-hole position adjusting plate 633, and the locking nut cooperates with the hinge shaft 634. The limiting component 635 can axially clamp the hinge shaft 634 to prevent it from moving and allow it to rotate.

[0040] Furthermore, in the technical solution, a limiting connector 7 and a reinforcing connector 8 are provided between two adjacent reinforcing members 4 on the same side, with the limiting connector 7 located above the reinforcing connector 8.

[0041] In this embodiment, refer to Figure 7 As shown, the limiting connector 7 includes concrete pipe segments 71 symmetrically arranged on adjacent concrete foundations 42, a connecting rib 72 between the two concrete pipe segments 71, and a stop block 73 and a rubber pad 74 inside the concrete pipe segment 71, with the end of the connecting rib 72 abutting against the rubber pad 74.

[0042] Specifically, the connecting rib 72 can connect adjacent concrete foundations 42 and provide a reliable shear force transmission path to prevent relative slippage of the concrete foundations 42.

[0043] Furthermore, the technical solution includes a connecting anchor 81 pre-embedded in each high-pressure jet grouting pile 41, a first reinforced concrete connecting beam 82 cast on the top of the connecting anchor 81, and a second reinforced concrete connecting beam 83 between two adjacent first reinforced concrete connecting beams 82, and a plurality of pile-to-pile reinforcement bodies 84 provided on the second reinforced concrete connecting beam 83.

[0044] In detail, steel connecting anchors 81 are pre-embedded at the top of each high-pressure jet grouting pile 41. One end of the connecting anchor 81 is pre-embedded inside the high-pressure jet grouting pile 41, and the other end is exposed outside the high-pressure jet grouting pile 41. The first reinforced concrete connecting beam 82 is cast in place at the position of the exposed connecting section, and the exposed connecting sections of each high-pressure jet grouting pile 41 are integrally cast and formed with the concrete pile cap 42 to form an integrated pile-beam-pile structure.

[0045] Furthermore, a load-reducing layer 9, typically 10-20 cm thick, is laid between the load lever member 5 and the top plate 3. It should be laid flat to ensure uniformity, so that the backfill load can be evenly transferred to the fulcrum lever member 6.

[0046] Example 2 Based on Embodiment 1, this application provides a construction method for an open-cut tunnel structure, comprising the following steps: Excavation of foundation pits: Open excavation work is carried out in the construction area. The foundation pit is excavated within the scope and depth required by the design to ensure the stability of the foundation pit slope and avoid safety hazards such as collapse.

[0047] A base slab 1 is poured at the bottom of the excavation pit to ensure its design strength and stability. Side walls 2 are then constructed on both sides of the pit. These side walls 2 must possess good waterproofing and compressive strength to meet structural stress and waterproofing requirements, ensuring tunnel safety. The top slab 3 is constructed in close connection with the side walls 2, using reinforced concrete to ensure its strength. High-pressure jet grouting piles 41 are then installed outside the side walls 2, with concrete foundations 42 poured atop each pile.

[0048] Construction of the lateral load transfer zone: The area outside side wall 2 is defined as the load transfer zone. This portion of the soil will bear part of the horizontal load transferred through load lever member 5. The soil outside side wall 2 is reinforced using high-pressure jet grouting piles, soil mixing piles, and other reinforcement measures to improve the lateral bearing capacity of the soil. Then, the lateral load transfer zone is compacted in layers to ensure the compaction of the reinforced layer meets design requirements.

[0049] On the concrete foundation 42 outside side wall 2, the installation position of the fulcrum lever member 6 is precisely marked according to the installation position of the load lever member 5. The fulcrum lever member 6 is connected to the concrete foundation 42 by a composite hinge support 63. This ensures that the fulcrum lever member 6 can rotate smoothly under load.

[0050] A load lever component 5 is erected above the top slab 3, ensuring that its installation position meets design requirements and its inclination angle conforms to mechanical principles. Both ends of the load lever component 5 are connected to corresponding fulcrum lever components 6. The load lever component 5 and the fulcrum lever components 6 are connected by ball joint supports 62, ensuring the load lever component 5 is firmly and stably installed and can withstand the gradual load during backfilling. Multiple sets of load lever components 5 are arranged along the longitudinal direction of the tunnel and connected by longitudinal connecting components to form a continuous, integrated load-bearing system.

[0051] An intelligent monitoring system is installed, with sensors installed in the tunnel structure to monitor information such as stress and deformation of the roof slab 3 and sidewalls 2. The system can provide real-time feedback and automatically adjust the angle of the load lever component 5 and the construction speed of backfill soil through data analysis and preset parameters.

[0052] Lay a load-reducing layer. The load-reducing layer 9 is evenly laid between the load lever member 5 and the top plate 3, with a thickness generally of 10-20cm. It should be laid flat to ensure uniformity, so that the backfill load can be evenly transferred to the fulcrum lever member 6.

[0053] Layered backfilling is carried out using soil with good compaction properties. The thickness of each layer is controlled between 20 and 40 cm. Each layer of soil is fully compacted during backfilling. During the backfilling process, the load lever member 5 is gradually loaded by the pressure of the backfill soil, resulting in rotation and slight settlement. The vertical load is gradually converted into a horizontal load and then transferred to the lateral load transfer zone through the fulcrum lever member 6.

[0054] Specific application examples The specific application of a cut-and-cover tunnel structure in the construction process of cut-and-cover tunnels is now described in detail with reference to Embodiment 1 and Embodiment 2.

[0055] In the specific use of the open-cut tunnel structure of this application: a bottom slab 1 is poured at the bottom of the foundation pit, and side walls 2 are constructed on both sides of the foundation pit. High-pressure jet grouting piles 41 are arranged outside the side walls 2, and a concrete pile cap 42 is poured on the top of the high-pressure jet grouting piles 41. Determine the extent of the load transfer zone on the outer side of side wall 2, and perform layered compaction treatment on the lateral load transfer zone. Install the top plate 3 and the fulcrum lever member 6, and connect the fulcrum lever member 6 to the concrete foundation 42 through the composite hinge support 63 to ensure that the fulcrum lever member 6 can rotate smoothly under load. A load lever component 5 is installed above the top plate 3, and the load lever component 5 is connected to the fulcrum lever component 6 via a ball joint support 62. A load-reducing layer 9 is evenly laid between the load lever component 5 and the top plate 3; Soil with good compaction properties is selected for backfilling in layers, with each layer controlled to be 20-40cm thick. Each layer of soil is fully compacted during backfilling. During the backfilling process, the load lever member 5 is gradually loaded by the pressure of the backfill soil, resulting in rotation and slight settlement, gradually converting the vertical load into a horizontal load, which is then transferred to the lateral load transfer zone through the fulcrum lever member 6.

[0056] During the layered backfilling process, the eccentric position of the hinge shaft 634 and the multi-hole position adjustment disc 633 is dynamically adjusted according to the structural stress state of the backfilling stage, thereby changing the lever arm and realizing the transfer of the vertical backfill load to the lateral soil. After the backfilling is completed, the eccentric position is locked and the connecting rods set between adjacent load lever components 5 form an integral force system.

[0057] It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this invention, and these should also be considered within the scope of protection of this invention. These modifications and improvements will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A cut-and-cover tunnel structure, comprising a bottom slab (1) cast at the bottom of a pit and side walls (2) provided on both sides of the bottom slab (1), wherein a top slab (3) is connected to the top of the side walls (2), characterized in that: Each sidewall (2) is provided with multiple reinforcing members (4) at intervals on the outside. The reinforcing members (4) on each side are linearly and equidistantly distributed along the longitudinal direction of the sidewall (2). The corresponding reinforcing members (4) on both sides form a group. Multiple load lever components (5) are arranged horizontally at equal intervals above the top plate (3). Each load lever component (5) cooperates with the corresponding group of reinforcement components (4), and the load lever components (5) and reinforcement components (4) are connected by fulcrum lever components (6).

2. The cut-and-cover tunnel structure according to claim 1, characterized in that: A limiting connector (7) and a reinforcing connector (8) are provided between two adjacent reinforcing members (4) on the same side, wherein the limiting connector (7) is located above the reinforcing connector (8).

3. The cut-and-cover tunnel structure according to claim 1, characterized in that: The reinforcing component (4) includes multiple high-pressure jet grouting piles (41) arranged on the outside of the side wall (2). A concrete foundation (42) is poured on the top of the high-pressure jet grouting pile (41), and an enlarged pile head (43) is provided at the bottom of the high-pressure jet grouting pile (41).

4. The cut-and-cover tunnel structure according to claim 3, characterized in that: The load lever member (5) is a rod with a T-shaped or L-shaped cross section, and the inclination angle of the load lever member (5) is 5° to 30°.

5. A cut-and-cover tunnel structure according to claim 4, characterized in that: The fulcrum lever component (6) includes a fulcrum lever (61) and ball joint supports (62) and composite joint supports (63) disposed at both ends of the fulcrum lever (61). The ball joint supports (62) are connected to the load lever component (5), and the composite joint supports (63) are connected to the concrete foundation (42).

6. The cut-and-cover tunnel structure according to claim 5, characterized in that: The composite hinge support (63) includes a hinge lug (631), an eccentric connecting block (632), a multi-hole position adjustment disc (633), a hinge shaft (634), and a limiting component (635). One side of the hinged ear plate (631) is connected to the concrete foundation (42), and the other side is connected to the eccentric connecting block (632). The eccentric connecting block (632) is connected to the multi-hole position adjustment plate (633). One end of the hinge shaft (634) is inserted through the center hole of the multi-hole position adjustment plate (633), and the other end is connected to the fulcrum lever (61). A limit component (635) is provided near the multi-hole position adjustment plate (633) of the hinge shaft (634).

7. A cut-and-cover tunnel structure according to claim 2, characterized in that: The limiting connector (7) includes concrete segments (71) symmetrically arranged on adjacent concrete foundations (42), a connecting rib (72) between the two concrete segments (71), and a stop block (73) and a rubber pad (74) inside the concrete segments (71), with the end of the connecting rib (72) abutting against the rubber pad (74).

8. A cut-and-cover tunnel structure according to claim 7, characterized in that: The reinforcing connector (8) includes a connecting anchor (81) pre-embedded in each high-pressure jet grouting pile (41), a first reinforced concrete connecting beam (82) is poured on the top of the connecting anchor (81), and a second reinforced concrete connecting beam (83) is provided between two adjacent first reinforced concrete connecting beams (82), and multiple pile reinforcement bodies (84) are provided on the second reinforced concrete connecting beam (83).

9. A cut-and-cover tunnel structure according to claim 6, characterized in that: A load-reducing layer (9) is laid between the load lever member (5) and the top plate (3).

10. A construction method for an open-cut tunnel structure, characterized in that: Includes the following steps: Step 1: Pour the bottom slab (1) at the bottom of the foundation pit, and construct the side walls (2) on both sides of the foundation pit. Arrange high-pressure jet grouting piles (41) outside the side walls (2), and pour concrete pile caps (42) on the top of the high-pressure jet grouting piles (41). Step 2: Determine the extent of the load transfer zone on the outside of the side wall (2), and perform layered compaction on the lateral load transfer zone; Step 3: Install the top plate (3) and the fulcrum lever member (6), and connect the fulcrum lever member (6) to the concrete foundation (42) through the composite hinge support (63) to ensure that the fulcrum lever member (6) can rotate smoothly under the load; Step 4: Install a load lever member (5) above the top plate (3), and connect the load lever member (5) to the fulcrum lever member (6) through a ball joint support (62); Step 5: Evenly lay the load-reducing layer (9) between the load lever member (5) and the top plate (3); Step 6: Select soil with good compaction for backfilling in layers. The thickness of each layer is controlled between 20 and 40 cm. During backfilling, each layer of soil is fully compacted. During the backfilling process, the load lever member (5) is gradually loaded by the backfill soil pressure, resulting in rotation and slight subsidence. The vertical load is gradually converted into a horizontal load and transferred to the lateral load transfer zone through the fulcrum lever member (6).

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