A stiffness-adjustable super-high fill tunnel active-passive collaborative load control structure

Abstract

This invention discloses a stiffness-adjustable active-passive coordinated load control structure for ultra-high embankment tunnels, relating to the field of tunnel support structure technology. To address the problem of existing high-embankment buried tunnels where structural stiffness cannot be adjusted and it is difficult to actively guide and disperse embankment pressure under embankment heights exceeding 80 meters, the following technical solution is proposed: It includes corrugated steel plates, anchor bolts, granular filler material, and a metal mesh. The corrugated steel plates are circumferentially assembled to form the innermost layer of the tunnel support; the granular filler material, wrapped in the metal mesh, is placed around the outside of the corrugated steel plates; the anchor bolts penetrate the granular filler material, the metal mesh, and the corrugated steel plates. This invention achieves active control of structural stiffness by adjusting the overlap length of the corrugated steel plates through the sliding adjustment of the anchor bolts within the elongated bolt holes. Simultaneously, the flexible enclosure formed by the granular filler material and the metal mesh can guide and disperse the pressure of the overlying embankment.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering support technology, specifically to a dynamic and passive coordinated load control structure for ultra-high embankment tunnels with adjustable stiffness. Background Technology

[0002] With the rapid development of transportation infrastructure construction, tunnel projects in mountainous areas, high embankment sections, and complex geological regions are increasing. Under high embankment conditions, especially in ultra-high embankment buried tunnels with a fill height exceeding 80 meters, the tunnel structure must withstand the enormous load from the thick overlying fill for a long period of time. The vertical and lateral pressures generated by the self-weight of the fill are extremely high, and the structural stress conditions are extremely complex, which can easily lead to engineering disasters such as structural settlement, cracking, local damage, or even overall instability.

[0003] Currently, traditional high-fill buried tunnels typically employ rigid lining structures or corrugated steel plate structures for support. Rigid lining structures, such as reinforced concrete linings, have high stiffness but poor deformation capacity, making it difficult to adapt to ultra-high fill loads. This leads to severe local stress concentration, easily causing cracks to develop and gradually extend to the entire structure. While corrugated steel plate structures possess a certain degree of flexibility and deformation coordination, their load-bearing capacity faces severe challenges under ultra-high fill loads exceeding 80 meters. Furthermore, in existing corrugated steel plate tunnel support systems, the corrugated plates are circumferentially spliced ​​to form a fixed stiffness, making it impossible to adjust the stiffness according to changes in the actual fill load, thus failing to simultaneously meet the dual requirements of load-bearing safety and deformation adaptability.

[0004] Furthermore, the fill material in ultra-high embankment areas exhibits a combination of effects, including self-weight consolidation settlement, construction disturbance, and uneven foundation settlement. At burial depths exceeding 80 meters, these effects are significantly amplified, further exacerbating the uncertainty of the tunnel structure's stress. Traditional support structures typically passively bear the fill load; once the load exceeds design expectations, the structural safety reserve faces a severe test, resulting in extremely high maintenance and reinforcement costs.

[0005] Therefore, there is an urgent need to propose a new type of tunnel support structure that can leverage the flexibility of steel structures, possess the ability to actively adjust stiffness, and coordinate the dispersion and guidance of fill pressure, so as to adapt to the complex stress environment under ultra-high fill conditions of over 80 meters and improve the mechanical adaptability and long-term safety of tunnels. Summary of the Invention

[0006] The purpose of this invention is to provide a stiffness-adjustable active-passive coordinated load control structure for ultra-high embankment tunnels, in order to solve the problem that the structural stiffness of existing high embankment buried tunnels cannot be adjusted and it is difficult to actively guide and disperse the embankment pressure when the embankment height exceeds 80 meters.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: An adjustable stiffness ultra-high embankment tunnel active and passive load control structure includes corrugated steel plates, anchor bolts, granular filling material, and metal mesh. Corrugated steel plates are assembled circumferentially to form the innermost layer of tunnel support; The granular filler material is wrapped in a metal mesh and then placed around the outside of the corrugated steel sheet; The anchor bolts penetrate the granular filler material, metal mesh, and corrugated steel plate.

[0008] Furthermore, the connection points of adjacent corrugated steel plates are provided with adjacent elongated bolt holes, which are through holes that penetrate the thickness of the corrugated steel plate and extend along the circumferential direction of the corrugated steel plate.

[0009] Furthermore, it also includes bolts and washers. The end of the anchor rod is provided with a threaded section. The threaded section of the anchor rod passes through the long bolt hole. The washer is fitted on the threaded section and abuts against the surface of the corrugated steel plate. The bolt is threadedly connected to the threaded section and presses the washer.

[0010] Furthermore, the fixed position of the anchor bolt in the long bolt hole is adjustable along the length of the hole to change the overlap length of adjacent corrugated steel plates.

[0011] Furthermore, the granular filler material is one or more of crushed stone, gravel, slag, recycled concrete aggregate, and ceramsite.

[0012] Furthermore, the particle size range of the particulate filler material is 20mm to 80mm.

[0013] Furthermore, the metal mesh is a flexible woven metal wire mesh, which wraps granular filler material to form a flexible enclosure, and the edges of the metal mesh are fixedly connected to the anchor rods.

[0014] Furthermore, the corrugated steel plate is a corrugated arc-shaped plate with corrugations extending circumferentially along the tunnel.

[0015] Furthermore, the mesh size of the metal mesh is larger than the diameter of the anchor rod.

[0016] The present invention has the following beneficial effects: By adjusting the sliding of the anchor rod in the long bolt hole, the present invention changes the overlap length of adjacent corrugated steel plates, thereby achieving active control of the overall structural stiffness and taking into account both load-bearing safety and deformation adaptability requirements.

[0017] In addition, the gabion-like flexible enclosure formed by granular filling material and metal mesh can actively guide and disperse the pressure of the overlying soil, avoiding the concentrated load on the tunnel body. The stiffness adjustment of the steel corrugated plate and the load guidance of the flexible enclosure work together to form a combined active and passive load control mechanism, which can effectively adapt to the complex stress environment of ultra-high embankment conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a stiffness-adjustable ultra-high embankment tunnel active and passive coordinated load control structure device according to Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the anchor connection of an active-passive coordinated load control structure for an ultra-high embankment tunnel with adjustable stiffness according to Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of a stiffness-adjustable ultra-high embankment tunnel active and passive coordinated load control structure device according to Embodiment 2 of the present invention. Figure 4 This is a schematic diagram of the anchor connection of an active-passive coordinated load control structure for an ultra-high embankment tunnel with adjustable stiffness, according to Embodiment 2 of the present invention.

[0019] Figures 1 to 4 The reference numerals in the attached figures are respectively: 1-corrugated steel plate, 2-anchor rod, 3-granular filler material, 4-metal mesh, 5-long bolt hole, 6-bolt, 7-waist, 10-EPS foam board, 11-polyurethane foam layer, 12-external pad, 13-sleeve. Detailed Implementation

[0020] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0021] Example 1 An adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure includes a corrugated steel plate 1, anchor bolts 2, granular filling material 3, metal mesh 4, elongated bolt holes 5, bolts 6, and washers 7. The structure is integrally installed outside the tunnel and is composed of two parts: an inner corrugated steel plate structural unit with adjustable stiffness and an outer gabion-type flexible enclosure structural unit.

[0022] The corrugated steel plate 1 is circumferentially assembled on the innermost side, serving as the initial support structure for the tunnel. The corrugated steel plate 1 is a corrugated arc-shaped plate, with its corrugations extending circumferentially along the tunnel to enhance its load-bearing capacity. Adjacent corrugated steel plates 1 are connected by adjacent elongated bolt holes 5, which extend circumferentially along the corrugated steel plate 1, for the installation and sliding adjustment of anchor bolts 2.

[0023] The granular filler material 3 is wrapped by the metal mesh 4 to form a flexible gabion enclosure, which is arranged around the outside of the corrugated steel plate 1. The granular filler material 3 is one or more of crushed stone, gravel, slag, recycled concrete aggregate, and ceramsite, with a particle size range of 20mm to 80mm. The metal mesh 4 is a flexible woven metal wire mesh with good flexibility and tensile strength, used to wrap the granular filler material 3 to form a flexible enclosure. The edges of the metal mesh 4 are fixedly connected to the anchor bolts 2.

[0024] Anchor bolt 2 passes through granular filler material 3, metal mesh 4, and corrugated steel plate 1, and is inserted into elongated bolt holes 5. Anchor bolt 2 passes through both the mesh openings of the metal mesh 4 and the elongated bolt holes 5 on the corrugated steel plate 1. The mesh opening diameter is larger than the diameter of anchor bolt 2 to facilitate the insertion and installation of anchor bolt 2.

[0025] Anchor rod 2 is fixed in elongated bolt hole 5 by bolt 6 and washer 7. When structural stiffness needs to be adjusted, bolt 6 is loosened, and anchor rod 2 can slide along elongated bolt hole 5 to change the overlap length of adjacent corrugated steel plates 1. Since elongated bolt hole 5 extends circumferentially along corrugated steel plate 1, when anchor rod 2 slides along elongated bolt hole 5, it can change the circumferential overlap length of adjacent corrugated steel plates 1. When the overlap length increases, the overall stiffness of corrugated steel plate 1 increases; when the overlap length decreases, the overall stiffness of corrugated steel plate 1 decreases, thereby achieving active control of the overall structural stiffness.

[0026] In this embodiment, multiple anchor bolts 2 are arranged at intervals along the circumference of the tunnel, and each anchor bolt 2 is connected to an overlapping part of an adjacent corrugated steel plate 1. Granular filling material 3 and metal mesh 4 surround and fill the annular space between the outer side of the corrugated steel plate 1 and the external soil to form an annular load buffer layer.

[0027] In practical engineering applications, construction workers first assemble the bottom corrugated steel plate 1, with the pre-drilled long bolt holes 5 in their initial positions. Then, metal mesh 4 is laid sequentially on the outside and filled with granular filler material 3 to form an enclosure. Anchor bolts 2 are inserted to connect the metal mesh 4 to the corrugated steel plate 1, initially fixing but not fully tightening the bolts 6. Based on the actual backfill load, during construction or operation, the position of the anchor bolts 2 in the long bolt holes 5 is adjusted to change the overlap length of adjacent corrugated steel plates 1, achieving active stiffness control. This allows the structure to actively guide and disperse the pressure of the overlying backfill, forming a coordinated active and passive load control mechanism.

[0028] Example 2 Based on Example 1, this embodiment adds a passive unloading layer to the outside of the gabion flexible enclosure, forming a multi-level active and passive collaborative load control structure system.

[0029] Specifically, in this embodiment, EPS foam board 10 and polyurethane foam layer 11 are added sequentially from the inside to the outside of the flexible wrapping body composed of granular filling material 3 and metal mesh 4 in Example 1. The EPS foam board 10 is laid close to the outer surface of the flexible wrapping body, and the polyurethane foam layer 11 is disposed on the outside of the EPS foam board 10, directly contacting the surrounding soil and rock mass of the tunnel.

[0030] EPS foam board 10 is a polystyrene foam board, which is lightweight and compressible. Under the pressure of surrounding rock, it absorbs part of the load through its own compression deformation, forming the first-level passive unloading buffer layer. Polyurethane foam layer 11 is a high-compression polymer material layer, which is laid on the outside of EPS foam board 10 by spraying or prefabricating panels. It has good energy dissipation and deformation coordination capabilities, forming the second-level passive unloading buffer layer.

[0031] In this embodiment, the anchor rod 2 of embodiment 1 extends further outward, passing through the flexible wrapping body composed of steel corrugated plate 1, granular filling material 3 and metal mesh 4 in sequence, EPS foam board 10 and polyurethane foam layer 11. Its outer end is fixedly connected to an external pad 12 by bolts 6 and washers 7, thereby compressing the above-mentioned layers into a whole.

[0032] The load transfer and control mechanism of this embodiment is as follows: The pressure of the surrounding rock and soil mass first acts on the outermost polyurethane foam layer 11, and after being buffered and dissipated by it, it is transferred to the EPS foam board 10, where it is further compressed and absorbs energy. The remaining load is transferred to the gabion-type flexible enclosure composed of granular filling material 3 and metal mesh 4. Stress is dispersed through frictional slippage and rearrangement between particles, and the stiffness is actively controlled by adjusting the prestress of the anchor bolts 2. Finally, the load is borne by the innermost corrugated steel plate 1. The corrugated steel plate 1 changes the overlap length by sliding the anchor bolts 2 in the long bolt holes 5, thus achieving active matching of overall stiffness. Therefore, this embodiment forms a multi-level collaborative load control system of "passive buffering - active regulation - structural bearing", which can respond to different stages of surrounding rock loads in a graded manner, and is especially suitable for ultra-high embankment tunnel conditions.

[0033] In this embodiment, a sleeve 13 is also fitted on the anchor rod 2 at the position where it penetrates the polyurethane foam layer 11 and the EPS foam board 10. The inner diameter of the sleeve 13 is larger than the diameter of the anchor rod 2, so as to provide free sliding space for the anchor rod 2 when the foam layer is compressed and deformed, and to prevent the anchor rod 2 from being damaged by shear.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A stiffness-adjustable ultra-high embankment tunnel active-passive coordinated load control structure, characterized in that, Includes corrugated steel plate (1), anchor bolt (2), granular filler material (3) and metal mesh (4); The corrugated steel plate (1) is circumferentially assembled to form the innermost layer of the tunnel support; The granular filler material (3) is wrapped around the outside of the corrugated steel plate (1) after being wrapped by the metal mesh (4); The anchor (2) penetrates the granular filler material (3), the metal mesh (4), and the corrugated steel plate (1).

2. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 1, characterized in that, The connecting parts of the adjacent corrugated steel plates (1) are provided with adjacent elongated bolt holes (5). The elongated bolt holes (5) are through holes that penetrate the thickness of the corrugated steel plates (1) and extend along the circumferential direction of the corrugated steel plates (1). The anchor rod (2) passes through the elongated bolt holes (5).

3. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 2, characterized in that, It also includes bolts (6) and washers (7). The end of the anchor rod (2) is provided with a threaded section. The threaded section of the anchor rod (2) passes through the long bolt hole (5). The washers (7) are fitted on the threaded section and abut against the surface of the corrugated steel plate (1). The bolts (6) are threadedly connected to the threaded section and press the washers (7) together.

4. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 2, characterized in that, The fixed position of the anchor rod (2) in the long bolt hole (5) is adjustable along the length of the hole to change the overlap length of the adjacent corrugated steel plates (1).

5. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 1, characterized in that, The granular filler material (3) is one or more of crushed stone, gravel, slag, recycled concrete aggregate, and ceramsite.

6. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 5, characterized in that, The particle size range of the granular filler material (3) is 20 mm to 80 mm.

7. The adjustable stiffness ultra-high embankment tunnel active-passive coordinated load control structure according to claim 1, characterized in that, The metal mesh (4) is a flexible metal wire woven mesh. The metal mesh (4) wraps the granular filling material (3) to form a flexible wrapping body. The mesh edge of the metal mesh (4) is fixedly connected to the anchor rod (2).

8. The stiffness-adjustable ultra-high embankment tunnel active-passive coordinated load control structure according to claim 1, characterized in that, The corrugated steel plate (1) is a corrugated arc-shaped plate, and the corrugations extend circumferentially along the tunnel.

9. The stiffness-adjustable ultra-high embankment tunnel active-passive coordinated load control structure according to claim 1, characterized in that, The mesh size of the metal mesh (4) is larger than the diameter of the anchor rod (2).

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