A tunnel-road transition structure suitable for soft rock subgrade

Abstract

The utility model relates to railway roadbed engineering technical field, concretely relates to a kind of tunnel road transition structure suitable for soft rock roadbed, tunnel road transition structure includes cover plate, elastic compression layer and jack, the cover plate is set in the top of roadbed and is connected between tunnel inverted arch and roadbed surface layer, the elastic compression layer is set between the cover plate and the roadbed;The roadbed is located in the top of soft rock layer;The side edge of the cover plate side is rotatably connected with the tunnel inverted arch or the roadbed surface layer, the jack is set in the top of the cover plate, the jack can apply pressure to the cover plate so that the cover plate is aligned with the tunnel inverted arch or the roadbed surface layer. The side edge of the cover plate can be always aligned with the roadbed surface layer by controlling the pressure applied by the jack above the cover plate, to avoid the occurrence of fault block at tunnel road interface, to ensure the smooth transition of tunnel road interface.

Description

Technical Field

[0001] This utility model relates to the field of railway subgrade engineering technology, and in particular to a tunnel transition structure suitable for soft rock subgrades. Background Technology

[0002] The Sichuan-Chongqing region of my country is predominantly hilly, with widespread distribution of red bed soft rock. Constructing high-speed railways in this area inevitably involves cuttings and tunnels. In cutting sections, the red bed soft rock's expansion upon contact with water and its unloading rheological properties cause significant upward arching deformation of the roadbed after excavation. In tunnel sections, however, the upward arching deformation is smaller due to the smaller unloading during tunnel excavation and the constraint of the surrounding rock. The control of differential deformation in the transition section of ballastless track for high-speed railways requires extremely precise and stringent control. Because the upward arching deformation differs between cutting and tunnel sections, inadequate control of this differential deformation can easily lead to misalignment at the tunnel-road interface, and in severe cases, even train aborts, threatening the operational safety of the high-speed railway.

[0003] The most widely used tunnel transition type is the inverted trapezoidal transition structure along the longitudinal direction of the line. The filler in the trapezoidal area is graded crushed stone mixed with a small amount of cement. However, this transition structure cannot effectively control the differential deformation of the transition section of the red bed soft rock tunnel. Moreover, the differential deformation is concentrated at the tunnel interface, which is very easy to cause misalignment. Therefore, it is not suitable for the transition section of the red bed soft rock tunnel.

[0004] Therefore, there is an urgent need for a soft rock tunnel transition structure that is easy to construct, low in cost, and has promising application prospects, in order to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to overcome the technical problem that existing tunnel transition structures used in soft rock subgrades cannot effectively control differential deformation and are prone to misalignment, and to provide a tunnel transition structure suitable for soft rock subgrades.

[0006] This utility model provides a tunnel transition structure suitable for soft rock subgrades, including a cover plate, an elastic compression layer, and jacks. The cover plate is disposed above the subgrade and connected between the tunnel invert and the subgrade surface. The elastic compression layer is disposed between the cover plate and the subgrade. The subgrade is located above the soft rock layer. One side of the cover plate is rotatably connected to the tunnel invert or the subgrade surface. The jacks are disposed above the cover plate and can apply pressure to the cover plate to align the cover plate with the tunnel invert or the subgrade surface.

[0007] This invention, by installing a cover plate in the tunnel transition section and rotatably connecting one side of the cover plate to the tunnel invert or roadbed surface, aligns one side of the cover plate with the tunnel invert or roadbed surface. An elastic compression layer is installed below the cover plate; by using jacks above the cover plate to apply pressure and compress the elastic compression layer, the other side of the cover plate remains aligned with the roadbed surface or tunnel invert. Specifically, if one side of the cover plate is rotatably connected to the tunnel invert, the other side of the cover plate can be rotatably connected to the tunnel invert. The pressure of the jack compresses the elastic compression layer to align it with the roadbed surface. By controlling the pressure applied by the jack, the side of the cover plate can always be aligned with the roadbed surface, avoiding misalignment at the tunnel interface and ensuring a smooth transition. Alternatively, one side of the cover plate can be rotated and connected to the roadbed surface, while the other side of the cover plate can be compressed under the pressure of the jack to align with the tunnel invert. This also avoids misalignment at the tunnel interface by controlling the pressure of the jack.

[0008] Preferably, the system also includes an anchor cable, one end of which passes through the cover plate and is connected to the jack, and the other end of which is anchored in a stable layer below the soft rock layer.

[0009] By connecting anchor cables to the jacks and anchoring them in a stable layer below the soft rock layer, a stable point of force can be provided for the jacks when pressure is applied to the cover plate, ensuring that the jacks provide sufficient pressure to the cover plate. Of course, in addition to anchor cables, other methods can be used to fix the point of force on the jacks. For example, installing a fixed bracket above the jacks and connecting it to the roadbed surface or the tunnel invert can also achieve the same effect of a fixed point of force.

[0010] Preferably, the system further includes anchor piles located below the elastic compression layer and corresponding to the anchor cable. The anchor piles pass through the soft rock layer, with the upper end extending into the roadbed and the lower end extending into the stabilizing layer. The anchor cable is threaded through the anchor piles.

[0011] To enhance the anchoring effect of the anchor cable, anchor piles can be installed at the corresponding positions of the anchor cable, with the upper and lower ends of the anchor piles penetrating the soft rock layer into the roadbed and the stable layer, respectively. The anchor cable can then be inserted into the anchor piles, which can significantly improve the anchoring effect and pull-out resistance, thereby increasing the pressure applied by the jack to the cover plate.

[0012] Preferably, the anchor pile is fitted with a sleeve, and the sleeve is made of steel.

[0013] Preferably, the outer side of the sleeve is wrapped with an elastic isolation layer, which is located in the soft rock layer and the roadbed.

[0014] An elastic isolation layer is wrapped around the upper part of the anchor pile, which can reduce the horizontal stress on the anchor pile, avoid the adverse effects of the surrounding soil pressure on the anchor pile and its top cover plate, reduce the upward arching force of the upper strata on the anchor pile, and improve the pull-out resistance of the anchor pile; a sleeve is used to isolate the elastic isolation layer from the anchor pile body.

[0015] Preferably, the material of the elastic insulating layer includes asphalt.

[0016] Preferably, the cover plate and the tunnel invert are rotatably connected by a rotating support, and the transition structure includes two jacks, which are disposed on the side of the cover plate near the roadbed surface and spaced apart from each other.

[0017] Preferably, both jacks are connected to a control base station, which can synchronously adjust the pressure applied by the two jacks to the cover plate.

[0018] Here, hydraulic jacks can be used. Two hydraulic jacks can be adjusted synchronously by controlling the base station to match the elevation of the cover plate on the side away from the invert arch with the elevation of the adjacent roadbed surface, thus avoiding misalignment and achieving a smooth transition between the tunnel and the road.

[0019] Preferably, an expansion joint is formed between the cover plate and the roadbed surface.

[0020] An expansion joint is formed between the cover plate and the roadbed surface on the side away from the tunnel arch, which can prevent the cover plate and the adjacent roadbed surface from being squeezed and deformed due to thermal expansion and contraction.

[0021] Preferably, the material of the elastic compression layer includes a rubber sheet, SBS modified bitumen, or polystyrene foam board.

[0022] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0023] 1. This utility model provides a tunnel transition structure suitable for soft rock subgrades. By installing a cover plate in the tunnel transition section and rotatably connecting one side of the cover plate to the tunnel invert or subgrade surface, one side of the cover plate can be aligned with the tunnel invert or subgrade surface. An elastic compression layer is installed below the cover plate. A jack above the cover plate can be used to apply pressure to the cover plate and compress the elastic compression layer, keeping the other side of the cover plate aligned with the subgrade surface or tunnel invert. Specifically, if one side of the cover plate is rotatably connected to the tunnel invert, then the cover plate... The other side of the cover plate can be compressed under the pressure of the jack to align the elastic compression layer with the roadbed surface. By controlling the pressure applied by the jack, the side of the cover plate can always be aligned with the roadbed surface, avoiding misalignment at the tunnel interface and ensuring a smooth transition at the tunnel interface. Alternatively, one side of the cover plate can be rotated and connected to the roadbed surface, and the other side of the cover plate can be compressed under the pressure of the jack to align with the tunnel invert. The effect of avoiding misalignment at the tunnel interface can also be achieved by controlling the pressure of the jack.

[0024] 2. The top surface of the cover plate can be flush with the top surface of the tunnel invert and can be connected to the top surface of the tunnel invert using a rotating support, which can avoid misalignment at the tunnel interface and distribute the uneven settlement of the tunnel transition section evenly on the cover plate.

[0025] 3. An elastic compression layer is set between the cover plate and the roadbed below. When the roadbed below undergoes upward arching deformation, the elastic compression layer undergoes compression deformation. By reserving a certain upward arching margin, the upward arching force of the roadbed on the cover plate can be effectively reduced.

[0026] 4. The anchor piles penetrate the roadbed and the upper arch soft rock layer and are embedded in the stable rock layer to enhance the pull-out resistance of the anchor piles. An elastic isolation layer is wrapped around the anchor pile body in the roadbed and the upper arch soft rock layer. The elastic isolation layer can be made of asphalt material. Asphalt has good waterproof, anti-corrosion and elastic properties, which can reduce the horizontal force on the anchor pile, avoid the adverse effects of the surrounding soil pressure on the anchor pile and its upper cover plate, and reduce the upward arching force of the upper strata on the anchor pile, thereby improving the pull-out resistance of the anchor pile.

[0027] 5. The cover plate is connected to the anchor piles by jacks. The anchor piles pass through the roadbed and the soft rock layer of the upper arch and are embedded in the stable rock layer. The jacks can be adjusted by hydraulic pumps to make the elevation of the cover plate on the side away from the invert arch match the elevation of the adjacent roadbed surface layer, so as to achieve a smooth transition of the tunnel.

[0028] 6. The anchor pile is equipped with an anchor cable. The lower end of the anchor cable can be buried in the stable layer and welded to the bottom reinforcement of the anchor pile. The upper end is anchored to the hydraulic jack. The hydraulic jack is controlled by the control base station. The height of the cover plate is controlled by adjusting the tension of the anchor cable through regular operation by personnel to ensure a smooth connection between the cover plate and the surface of the adjacent roadbed.

[0029] 7. An expansion joint is formed between the cover plate and the roadbed surface on the side away from the tunnel arch to prevent the cover plate from being squeezed and deformed by thermal expansion and contraction with the adjacent roadbed surface. Attached Figure Description

[0030] Figure 1 This is a longitudinal section view of the tunnel transition structure of this utility model applicable to soft rock roadbeds.

[0031] Figure 2 This is a top view of the tunnel transition structure of this utility model applicable to soft rock roadbeds.

[0032] Marked in the image:

[0033] 1. Cover plate, 2. Rotating support, 3. Elastic compression layer, 4. Anchor pile, 5. Elastic isolation layer, 6. Sleeve, 7. Anchor cable, 8. Jack, 9. Control base station, 10. Expansion joint, 11. Subgrade surface layer, 12. Subgrade, 13. Soft rock layer, 14. Stabilizing layer, 15. Tunnel invert. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments. However, it should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0035] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of this utility model is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the utility model solution or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on this utility model.

[0036] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0037] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0038] Furthermore, in the description of the embodiments of this utility model, "several", "multiple", and "several" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0039] Furthermore, in the description of the technical solution of this utility model, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "equipped with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0040] Example 1

[0041] This embodiment provides a tunnel transition structure suitable for soft rock subgrades.

[0042] Figure 1 This is a longitudinal section view of the tunnel transition structure of this utility model applicable to soft rock roadbed; Figure 2 This is a top view of the tunnel transition structure of this utility model applicable to soft rock roadbeds.

[0043] like Figures 1 to 2As shown, the tunnel transition structure of this utility model suitable for soft rock subgrade includes a cover plate 1, an elastic compression layer 3, and a jack 8. The cover plate 1 is set above the subgrade 12 and connected between the tunnel invert 15 and the subgrade surface layer 11. The elastic compression layer 3 is set between the cover plate 1 and the subgrade 12. By reserving a certain amount of upward arching allowance, the upward arching force of the subgrade 12 on the cover plate 1 can be effectively reduced. The subgrade 12 is located above the soft rock layer 13. One side of the cover plate 1 is rotatably connected to the tunnel invert 15 or the subgrade surface layer 11. The jack 8 is set above the cover plate 1. The jack 8 can apply pressure to the cover plate 1 to align the cover plate 1 with the tunnel invert 15 or the subgrade surface layer 11. The cover plate 1 is arranged outside the tunnel invert at the entrance and exit. The cover plate 1 can be made of reinforced concrete cast in place.

[0044] This invention, by installing a cover plate 1 in the tunnel transition section and rotatably connecting one side of the cover plate 1 to the tunnel invert 15 or the roadbed surface 11 via a rotating support 2, aligns one side of the cover plate 1 with the tunnel invert 15 or the roadbed surface 11. An elastic compression layer 3 is installed below the cover plate 1; pressure is applied to the cover plate 1 and compressed using a jack 8 above the cover plate 1, keeping the other side of the cover plate 1 aligned with the roadbed surface 11 or the tunnel invert 15. Specifically, if one side of the cover plate 1 is rotatably connected to the tunnel invert 15, then the other side of the cover plate 1... One side of the cover plate 1 can be compressed under the pressure of the jack 8 to align the elastic compression layer 3 with the roadbed surface layer 11. The pressure applied by the jack 8 can be controlled to ensure that the side of the cover plate 1 is always aligned with the roadbed surface layer 11, thus avoiding misalignment at the tunnel interface and ensuring a smooth transition at the tunnel interface. Alternatively, one side of the cover plate 1 can be rotatably connected to the roadbed surface layer 11, and the other side of the cover plate 1 can be compressed under the pressure of the jack 8 to align the elastic compression layer 3 with the tunnel invert arch 15. The pressure of the jack 8 can also be controlled to avoid misalignment at the tunnel interface.

[0045] In this embodiment, the tunnel transition structure also includes an anchor cable 7, one end of which passes through the cover plate 1 and is connected to the jack 8, and the other end of which is anchored in the stable layer 14 below the soft rock layer 13.

[0046] By connecting anchor cables 7 to the jack 8 and anchoring the anchor cables 7 in the stable layer 14 below the soft rock layer 13, a stable point of force can be provided for the jack 8 when pressure is applied to the cover plate 1 through the jack 8, which can ensure that the jack 8 provides sufficient pressure to the cover plate 1 when pressure is applied; of course, in addition to using anchor cables 7, the point of force of the jack 8 can also be fixed in other ways, such as installing a fixed bracket connected to the roadbed surface layer 11 or the tunnel invert arch 15 above the jack 8, which can also achieve the same effect of a point of force; here, the anchor cable 7 can be a steel wire rope.

[0047] In this embodiment, the tunnel transition structure also includes anchor piles 4, which are located below the elastic compression layer 3 and are correspondingly arranged with anchor cables 7. The anchor piles 4 pass through the soft rock layer 13, with the upper end of the anchor piles 4 extending into the roadbed 12 and the lower end of the anchor piles 4 extending into the stabilizing layer 14. The anchor cables 7 are inserted into the anchor piles 4. Specifically, the anchor piles 4 are located below the cover plate 1 on the side away from the tunnel invert arch 15. The cover plate 1 is connected to the anchor piles 4 through jacks 8. The anchor piles 4 pass through the roadbed 12 and the soft rock layer 13 and are embedded in the stabilizing layer 14.

[0048] To enhance the anchoring effect of the anchor cable 7, anchor piles 4 can be installed at the corresponding positions of the anchor cable 7, and the upper and lower ends of the anchor piles 4 can pass through the soft rock layer 13 and enter the roadbed 12 and the stable layer 14 respectively. The anchor cable 7 can be inserted into the anchor piles 4, which can significantly improve the anchoring effect and pull-out resistance, thereby increasing the pressure applied by the jack 8 to the cover plate 1.

[0049] Alternatively, the anchor pile 4 is fitted with a sleeve 6, and the outer side of the sleeve 6 is wrapped with an elastic isolation layer 5, which is located in the soft rock layer 13 and the roadbed 12.

[0050] An elastic isolation layer 5 is wrapped around the upper part of the anchor pile 4. Here, the elastic isolation layer 5 can be made of asphalt material. Asphalt has good waterproof, anti-corrosion and elastic properties, which can reduce the horizontal stress on the anchor pile 4 and avoid the adverse effects of the surrounding soil pressure on the anchor pile 4 and the cover plate 1 above it. It can also reduce the upward arching force of the upper stratum on the anchor pile 4 and improve the pull-out resistance of the anchor pile 4. The elastic isolation layer 5 is isolated from the anchor pile 4 by a sleeve 6. Of course, the elastic isolation layer 5 can also be made of other materials, such as rubber, etc. This utility model does not make a specific limitation on this.

[0051] Optionally, the cover plate 1 is rotatably connected to the tunnel invert 15. The tunnel transition structure includes two jacks 8, which are set on the side of the cover plate 1 near the roadbed surface 11 and spaced apart from each other. Of course, the cover plate 1 can also be rotatably connected to the roadbed surface 11. Specifically, the cover plate 1 and the tunnel invert 15 or the roadbed surface 11 can be connected by a rotating support 2 to achieve a rotatable connection. The rotating support 2 is similar to a hinge structure. The number of jacks 8 installed on the cover plate 1 is not limited to two and can be selected according to actual needs. This utility model does not make a specific limitation in this regard.

[0052] In this embodiment, both jacks 8 are connected to the control base station 9. The control base station 9 is used to adjust the pressure applied by the two jacks 8 to the cover plate 1. The control base station 9 can be connected to both jacks 8 at the same time, and can control the two jacks 8 to move synchronously to ensure that the elevation of the cover plate 1 at the two jacks 8 is consistent.

[0053] Here, the hydraulic jack 8 can be hydraulically operated. The hydraulic jack 8 can be adjusted by controlling the base station 9 to match the elevation of the side cover plate 1 away from the invert arch with the elevation of the adjacent roadbed surface layer 11, so as to avoid misalignment and achieve a smooth transition between the tunnel and the road.

[0054] Optionally, an expansion joint 10 is formed between the cover plate 1 and the roadbed surface 11.

[0055] An expansion joint 10 is formed between the side of the cover plate 1 away from the tunnel invert 15 and the roadbed surface 11, which can prevent the cover plate 1 and the adjacent roadbed surface 11 from being squeezed and deformed due to thermal expansion and contraction.

[0056] This structure not only effectively solves the problems of large differences in stiffness and uneven deformation in existing tunnel transition sections, making it impossible to control upward arching, but also is simple to construct, low in cost, and has broad application prospects.

[0057] Example 2

[0058] This embodiment provides a construction method for tunnel transition structures suitable for soft rock subgrades.

[0059] The construction method for tunnel transition structures suitable for soft rock subgrades in this embodiment is applied to the tunnel transition structures suitable for soft rock subgrades described above. The construction method includes the following steps:

[0060] S1: Excavate the existing road cut and fill the roadbed 12;

[0061] S2: Erect formwork and steel bars above the subgrade 12, pour concrete in the formwork to form cover plate 1, and rotate cover plate 1 to connect to tunnel invert arch 15 or subgrade surface 11.

[0062] S3: Remove the template, then lift the cover plate 1, and lay the elastic compression layer 3 on top of the roadbed 12;

[0063] S4: Install jacks 8 on cover plate 1 and apply pressure to cover plate 1 through jacks 8 to align cover plate 1 with tunnel invert arch 15 or roadbed surface 11.

[0064] In this embodiment, the method of rotating the cover plate 1 to the tunnel invert arch 15 or the roadbed surface layer 11 in step S2 includes:

[0065] S21: Install rotating bearing 2 on the tunnel invert arch 15 or the roadbed surface layer 11;

[0066] S22: Before pouring the cover plate 1, tie the movable end of the rotating support 2 to the reinforcing bar.

[0067] Alternatively, in step S3 above, the formwork can be removed after the concrete strength reaches 70% of the design strength.

[0068] Based on all the features of the tunnel transition structure in Example 1, the construction method of this example can be further refined as follows:

[0069] ① Excavate the existing road cut down to the lower surface of the roadbed 12 and level the site;

[0070] ② The transition section of the roadbed 12 filler material is filled simultaneously with the roadbed 12 and compacted in layers until the density meets the compaction standard requirements;

[0071] ③ Construct anchor pile 4, using manual excavation to form the hole, and then lower the sleeve 6 after cleaning the bottom;

[0072] ④ Place the reinforcing cage inside the sleeve 6 and pour concrete for the anchor pile 4;

[0073] ⑤ Fill the outside of the sleeve 6 with asphalt to form an elastic isolation layer 5;

[0074] ⑥ Erect the construction formwork at the position of cover plate 1, place the reinforcing steel of cover plate 1, tie the end of the hinged support cover plate 1 to the reinforcing steel cage of cover plate 1, and then pour concrete.

[0075] ⑦ After the concrete strength of cover plate 1 reaches 70% of the design strength, remove the side formwork, lift cover plate 1, remove the bottom formwork, and lay the elastic compression layer 3.

[0076] ⑧ Install anchor cable 7 at the center of anchor pile 4, lower cover plate 1, and connect cover plate 1 to anchor pile 4 through anchor cable 7 and jack 8.

[0077] ⑨ Use jack 8 to fine-tune the anchor cable 7 so that the elevation of the cover plate 1 is consistent with that of the adjacent roadbed surface layer 11, and adjust it regularly.

[0078] The compression modulus of the elastic compression layer 3 is lower than that of the soft rock layer 13, and it can be made of rubber sheet, SBS modified asphalt, or polystyrene foam board. The thickness of the elastic compression layer 3 ranges from 0.4 to 0.6 m, with a preferred value of 0.5 m. The diameter of the anchor pile 4 ranges from 1.4 to 1.6 m, with a preferred value of 1.5 m; the diameter of the steel sleeve 6 is 20 to 30 cm smaller than the borehole diameter.

[0079] In summary, this utility model provides a tunnel transition structure suitable for soft rock subgrades. By installing a cover plate in the tunnel transition section and rotatably connecting one side of the cover plate to the tunnel invert or subgrade surface, one side of the cover plate can be aligned with the tunnel invert or subgrade surface. An elastic compression layer is installed below the cover plate; jacks above the cover plate can apply pressure to the cover plate and compress the elastic compression layer, keeping the other side of the cover plate aligned with the subgrade surface or tunnel invert. Specifically, if one side of the cover plate is rotatably connected to the tunnel invert... The other side of the cover plate can be compressed under the pressure of the jack to align the elastic compression layer with the roadbed surface. By controlling the pressure applied by the jack, the side of the cover plate can always be aligned with the roadbed surface, avoiding misalignment at the tunnel interface and ensuring a smooth transition at the tunnel interface. Alternatively, one side of the cover plate can be rotated and connected to the roadbed surface, and the other side of the cover plate can be compressed under the pressure of the jack to align with the tunnel invert. The effect of avoiding misalignment at the tunnel interface can also be achieved by controlling the pressure of the jack.

[0080] The top surface of the cover plate can be flush with the top surface of the tunnel invert and can be connected to the top surface of the tunnel invert using a rotating support, which can avoid misalignment at the tunnel interface and distribute the uneven settlement of the tunnel transition section evenly on the cover plate.

[0081] An elastic compression layer is installed between the cover plate and the roadbed below. When the roadbed below undergoes upward arching deformation, the elastic compression layer undergoes compression deformation. By reserving a certain amount of upward arching allowance, the upward arching force of the roadbed on the cover plate can be effectively reduced.

[0082] The anchor piles penetrate the roadbed and the upper arch soft rock layer and are embedded in the stable rock layer to enhance the pull-out resistance of the anchor piles. An elastic isolation layer is wrapped around the anchor pile body in the roadbed and the upper arch soft rock layer. The elastic isolation layer can be made of asphalt material. Asphalt has good waterproof, anti-corrosion and elastic properties, which can reduce the horizontal force on the anchor pile, avoid the adverse effects of the surrounding soil pressure on the anchor pile and the cover plate above it, and reduce the upward arching force of the upper strata on the anchor pile, thereby improving the pull-out resistance of the anchor pile.

[0083] The cover plate is connected to the anchor piles by jacks. The anchor piles pass through the roadbed and the soft rock layer of the upper arch and are embedded in the stable rock layer. The jacks can be adjusted by hydraulic pumps to match the elevation of the cover plate on the side away from the invert arch with the elevation of the surface layer of the adjacent roadbed, so as to achieve a smooth transition of the tunnel.

[0084] The anchor pile is equipped with an anchor cable. The lower end of the anchor cable can be buried in the stable layer and welded to the bottom steel bar of the anchor pile. The upper end is anchored to the jack. The hydraulic jack is controlled by the control base station. The height of the cover plate is controlled by adjusting the tension of the anchor cable through regular operation by personnel to ensure that the cover plate is smoothly connected to the surface of the adjacent roadbed.

[0085] An expansion joint is formed between the cover plate and the roadbed surface on the side away from the tunnel arch to prevent the cover plate from being squeezed and deformed by thermal expansion and contraction with the adjacent roadbed surface.

[0086] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A tunnel transition structure suitable for soft rock subgrade, characterized in that, The system includes a cover plate (1), an elastic compression layer (3), and a jack (8). The cover plate (1) is positioned above the roadbed (12) and connected between the tunnel invert (15) and the roadbed surface (11). The elastic compression layer (3) is positioned between the cover plate (1) and the roadbed (12). The roadbed (12) is located above a soft rock layer (13). One side of the cover plate (1) is rotatably connected to the tunnel invert (15) or the roadbed surface (11). The jack (8) is positioned above the cover plate (1) and can apply pressure to the cover plate (1) to align the cover plate (1) with the tunnel invert (15) or the roadbed surface (11).

2. The tunnel transition structure suitable for soft rock subgrade according to claim 1, characterized in that, It also includes an anchor cable (7), one end of which passes through the cover plate (1) and is connected to the jack (8), and the other end of which is anchored in the stable layer (14) below the soft rock layer (13).

3. The tunnel transition structure suitable for soft rock subgrade according to claim 2, characterized in that, It also includes anchor piles (4), which are located below the elastic compression layer (3) and are correspondingly arranged with the anchor cable (7). The anchor piles (4) pass through the soft rock layer (13), the upper end of the anchor piles (4) extends into the roadbed (12), and the lower end of the anchor piles (4) extends into the stable layer (14). The anchor cable (7) is inserted into the anchor piles (4).

4. The tunnel transition structure suitable for soft rock subgrade according to claim 3, characterized in that, The anchor pile (4) is fitted with a sleeve (6), and the sleeve (6) is made of steel.

5. The tunnel transition structure suitable for soft rock subgrade according to claim 4, characterized in that, The sleeve (6) is wrapped with an elastic isolation layer (5) on the outside, which is located in the soft rock layer (13) and the roadbed (12).

6. The tunnel transition structure suitable for soft rock subgrade according to claim 5, characterized in that, The material of the elastic isolation layer (5) includes asphalt.

7. The tunnel transition structure suitable for soft rock subgrade according to any one of claims 1 to 6, characterized in that, The cover plate (1) and the tunnel invert (15) are rotatably connected by a rotating support (2). The transition structure includes two jacks (8), which are set on the cover plate (1) on the side close to the roadbed surface (11) and spaced apart from each other.

8. The tunnel transition structure suitable for soft rock subgrade according to claim 7, characterized in that, Both jacks (8) are connected to a control base station (9), which can synchronously adjust the pressure applied by the two jacks (8) to the cover plate (1).

9. The tunnel transition structure suitable for soft rock subgrade according to claim 7, characterized in that, An expansion joint (10) is formed between the cover plate (1) and the roadbed surface layer (11).

10. The tunnel transition structure suitable for soft rock subgrade according to any one of claims 1 to 6, characterized in that, The material of the elastic compression layer (3) includes rubber sheet, SBS modified bitumen or polystyrene foam board.

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