Rock column reinforcing device in large-section-to-small-section mutation section of shallow-buried tunnel

Abstract

This invention provides a rock column reinforcement device for abrupt transitions from large to small cross-sections in shallow-buried tunnels, relating to tunnel construction and engineering construction fields. The device includes: cast-in-place piles; a capping beam fixed to the top of the cast-in-place piles and integrated with them; and anchor pipes that pass through the small-section tunnel wall and are anchored to the cast-in-place piles. The cast-in-place piles are reinforced concrete structures, each including: side-stabilizing nails (multiple sets, each set with multiple nails arranged in a circumferential array); and a side-nailing nail transmission assembly housed inside the support cage. This device effectively increases the stability and connection strength of rock columns in tight clearances, thereby ensuring construction schedule and quality. It also has lower production costs, reduces construction difficulty, and solves the problems of limited construction space, the potential for overlapping spatial effects during construction that could endanger surface structures and personnel inside the tunnel, and the high difficulty of construction.

Description

Technical Field

[0001] This invention relates to the fields of tunnel construction and engineering construction technology, and in particular to a rock pillar reinforcement device in the abrupt transition section from a large cross-section to a small cross-section in shallow buried tunnels. Background Technology

[0002] Currently, there are numerous subway and tunnel construction projects in my country, and some difficult problems are often encountered during construction. The stability of rock pillars in shallow buried sections of tunnels with small clearance is one of them. In some cases, the width of the rock pillars in the two intersecting chambers is extremely small, which makes it difficult to guarantee the stability of the rock pillars. For example, in the section from Songhua Road Station to Huansha Road Station of Guiyang Metro Line 3 Phase I Project, the tunnel has a connecting line between Line 2 and Line 3 at ZDK32+104.215 on the left line, which connects to Huansha Road Station of Line 2. At this point, two equal-section, small-clearance intersecting chambers (area 39㎡) are divided from a large cross section (N cross section, area 143㎡). The small clearance section between the two equal-section intersecting chambers is as long as 55m, and the narrowest width of the rock pillars in the two intersecting chambers is only 1m. The space available for construction is small, and it is difficult to guarantee sufficient support strength for the rock pillars. The spatial effects brought about by the construction process can easily endanger the safety of ground structures and personnel inside the tunnel, making the construction very difficult. Summary of the Invention

[0003] This disclosure relates to a rock column reinforcement device in the abrupt transition section from large to small cross-section in shallow buried tunnels. It can effectively increase the stability and connection strength of rock columns with small clearance, thereby ensuring the construction period and quality, improving structural stability, and having good versatility. It also has low production costs and adopts a prefabricated support cage structure, avoiding the problem of difficult construction of small-diameter pile foundations and reducing construction difficulty.

[0004] The first aspect of this disclosure provides a rock pillar reinforcement device for the abrupt transition from a large cross-section to a small cross-section in shallow-buried tunnels, specifically including:

[0005] Cast-in-place piles are installed along the central rock column in the shallow buried section of the tunnel with small clearance, and cast-in-place piles are installed along the length of the tunnel on the outside of the two small cross-section tunnels.

[0006] The capping beam is fixed to the top of the cast-in-place pile and is integrated with the cast-in-place pile.

[0007] Locking anchor pipe, the locking anchor pipe passes through the small cross section tunnel wall and is anchored to the cast-in-place pile;

[0008] Cast-in-place piles are reinforced concrete cast-in-place structures, and include:

[0009] The support cage body is a cylindrical cage structure. The center of the support cage body is an inner support rod, and the outer side of the support cage body is an outer support rod arranged in a circular array. Multiple support cage bodies are provided, and multiple support cage bodies are installed vertically.

[0010] A rotating shaft is rotatably connected to the top of the support cage body;

[0011] Bottom stabilizing nails are arranged in a circumferential array at the bottom of the support cage body;

[0012] Side stabilizing nails are provided in multiple sets, and each set of side stabilizing nails has multiple pieces arranged in a circumferential array.

[0013] The side nail drive assembly is located inside the support cage body.

[0014] In at least some embodiments, the bottom circumferential array of the support cage body is provided with multiple sets of threaded holes, the top of the support cage body is provided with a circumferential array of light holes, the threaded hole of the bottom support cage body is bolted to a bottom stabilizing nail, the lower support cage body is inserted into the light hole by connecting bolts and connected to the threaded hole of the upper support cage body, and the top support cage body is connected to the crown beam by the light holes.

[0015] In at least some embodiments, the side nail drive assembly includes:

[0016] The drive thread is coaxially and fixedly connected to the rear of the rotating shaft;

[0017] The swing drive slider is slidably connected to the top of the uppermost support cage body. The swing drive slider and the drive thread are threaded together to form a lead screw and nut transmission pair.

[0018] In at least some embodiments, the side nail drive assembly further includes:

[0019] A swing linkage, which is hinged to the end of the swing drive slider;

[0020] The intermediate pivot is rotatably connected inside the inner support rod. The other end of the swing link is hinged to the intermediate pivot. The swing drive slider, the swing link, the intermediate pivot, and the support cage together constitute the crank-slider transmission structure.

[0021] In at least some embodiments, the side nail drive assembly further includes:

[0022] The swing arm is rotatably connected to the outside of the inner support rod;

[0023] The swing connector is located at the top of the swing arm and is plugged into the intermediate rotating shaft.

[0024] In at least some embodiments, the side nail drive assembly further includes:

[0025] The swing assembly is evenly distributed on the outside of the rotating connection outer support rod;

[0026] The side stabilizing pin is hinged to the outside of the swing arm and is slidably connected to the swing assembly. The swing arm, the swing assembly, the side stabilizing pin, and the support cage together constitute the crank-slider transmission mechanism.

[0027] In at least some embodiments, an upper connecting part is provided at the top of the intermediate rotating shaft, the upper connecting part having a groove structure, and a lower connecting part is provided at the bottom of the intermediate rotating shaft, the lower connecting part having a protruding structure, and the two intermediate rotating shafts are connected by the upper connecting part and the lower connecting part.

[0028] In at least some embodiments, the diameter of the cast-in-place piles is Φ0.6-0.8m, the pile spacing is 2-4m, and the bottom elevation of the cast-in-place piles is 3-4.5m lower than the invert arch of the tunnel main tunnel.

[0029] In at least some embodiments, when the width of the central rock column is 1-2m, the cast-in-place piles inside the central rock column are distributed along the center of the central rock column; when the width of the central rock column is greater than 2m and less than 4m, the cast-in-place piles inside the central rock column are arranged alternately along the length of the central rock column, close to both sides of the central rock column, and the distance between the cast-in-place piles and both sides of the central rock column is 0.2-1m.

[0030] In at least some embodiments, the anchor pipes at the location of the cast-in-place piles are anchored into the cast-in-place piles, and three anchor pipes are anchored into one side of each cast-in-place pile in the central rock column, and the anchor pipes on both sides of the three anchor pipes are anchored into the cast-in-place piles at an angle in an intersecting direction.

[0031] This invention provides a rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in shallow-buried tunnels, which has the following beneficial effects:

[0032] This invention can effectively reinforce the rock pillars in the shallow buried section of a tunnel with a small clearance before construction. Since additional reinforcement cannot be carried out during the construction of the shallow buried section of the tunnel with a small clearance, the stability of the rock pillars in the small clearance can be guaranteed, thereby effectively ensuring the construction period and construction quality, and the structural stability can also be better.

[0033] This invention, by employing a telescopic side-stabilizing nail structure, ensures that the main body of the support cage is centered in the pile pit, guaranteeing good mechanical properties after the cast-in-place pile is constructed. It also ensures a good clamping effect between the cast-in-place pile and the pit wall, guaranteeing connection stability and improving the support capacity of the cast-in-place pile. Furthermore, it can meet the construction requirements of different depths and diameters, and can address the issue of inconsistent pile diameters caused by varying widths of the central rock column during construction. It has good applicability, can be prefabricated in batches, eliminating the need for individual prefabrication of each cast-in-place pile, thus reducing production costs.

[0034] This invention can significantly increase the stability and connection strength of rock columns with small clearances, thereby effectively ensuring the construction period and quality, improving structural stability, and providing good versatility. It also has low production costs and adopts a prefabricated support cage structure, avoiding the problem of difficult construction of small-diameter pile foundations and reducing construction difficulty. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0036] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0037] In the attached diagram:

[0038] Figure 1 A schematic plan view of the structure of this application is shown;

[0039] Figure 2 A cross-sectional schematic diagram of the structure of this application is shown;

[0040] Figure 3 A side view of the structure of this application is shown;

[0041] Figure 4 A schematic diagram of the installation of the support cage body of the structure of this application is shown;

[0042] Figure 5 A schematic diagram of the support cage body of the structure of this application is shown;

[0043] Figure 6 A schematic diagram of the side-stabilizing nails of the structure of this application is shown;

[0044] Figure 7 A schematic diagram of the bottom of the support cage body of the structure of this application is shown;

[0045] Figure 8 A schematic diagram of the bottom stabilizing nail of the structure of this application is shown;

[0046] Figure 9A schematic diagram of the bottom stabilizing pin installation of the structure of this application is shown;

[0047] Figure 10 A schematic diagram of the side-mounted retaining pins of the structure of this application is shown;

[0048] Figure 11 A schematic diagram of the intermediate shaft transmission structure of this application is shown;

[0049] List of reference numerals

[0050] 1. Right-line small-section tunnel; 2. Left-line small-section tunnel; 3. Middle rock pillar; 4. Large-section tunnel; 5. Cast-in-place pile; 501. Support cage body; 5011. Outer support rod; 5012. Inner support rod; 502. Rotating shaft; 5021. Drive thread; 503. Swing drive slider; 504. Swing connecting rod; 505. Middle rotating shaft; 5051. Lower connecting part; 5052. Upper connecting part; 506. Swing arm; 601. Swing connector; 507. Side stabilizing nail; 508. Swing kit; 509. Connecting bolt; 510. Bottom stabilizing nail; 6. Locking foot anchor pipe; 7. Crown beam. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Example 1: Please refer to Figures 1 to 3 :

[0053] This invention proposes a rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in shallow-buried tunnels, comprising:

[0054] Cast-in-place pile 5: Cast-in-place pile 5 is constructed along the central rock column 3 in the shallow buried section of the tunnel with small clearance. At the same time, cast-in-place pile 5 is constructed along the length of the tunnel on the outside of the two small cross-section tunnels.

[0055] The capping beam 7 is fixed to the top of the cast-in-place pile 5, and the capping beam 7 is integrated with the cast-in-place pile 5.

[0056] Locking anchor pipe 6 passes through the small cross-section tunnel wall and is anchored to the cast-in-place pile 5;

[0057] In this embodiment of the disclosure, such as Figure 1As shown, the diameter of the cast-in-place pile 5 is Φ0.6-0.8m, the pile spacing of the cast-in-place pile 5 is 2-4m, and the bottom elevation of the cast-in-place pile 5 is 3-4.5m lower than the invert arch of the tunnel.

[0058] In this embodiment of the disclosure, such as Figure 1 As shown, when the width of the central rock column 3 is 1-2m, the cast-in-place piles 5 inside the central rock column 3 are distributed along the center of the central rock column 3; when the width of the central rock column 3 is greater than 2m and less than 4m, the cast-in-place piles 5 inside the central rock column 3 are arranged alternately along the length direction of the central rock column 3, close to both sides of the central rock column 3, and the distance between the cast-in-place piles 5 and both sides of the central rock column 3 is 0.2-1m.

[0059] In this embodiment of the disclosure, such as Figure 1-2 As shown, the anchor pipe 6 at the location of the cast-in-place pile 5 is anchored into the cast-in-place pile 5. Each cast-in-place pile 5 in the middle rock column 3 has three anchor pipes 6 anchored into one side, and the two anchor pipes 6 on both sides of the three anchor pipes 6 are anchored into the cast-in-place pile 5 at an angle in an intersecting direction.

[0060] Example 2: Please refer to Figures 1 to 3 :

[0061] The difference between this embodiment and Embodiment 1 is that the diameter of the cast-in-place pile 5 is Φ0.7m.

[0062] Example 3: Please refer to Figures 1 to 3 :

[0063] The difference between this embodiment and embodiment 1 is that the diameter of the cast-in-place pile 5 is Φ0.8m.

[0064] Example 4: Please refer to Figures 1 to 3 :

[0065] The difference between this embodiment and embodiment 1 is that when the width of the central rock column 3 is greater than 2m and less than 4m, the cast-in-place piles 5 are arranged alternately along the length direction of the central rock column 3, close to both sides of the central rock column 3. The distance between the cast-in-place piles 5 and both sides of the central rock column 3 is 0.2-1m, and the anchor pipes 6 corresponding to the positions of the cast-in-place piles 5 are anchored into the cast-in-place piles 5.

[0066] Example 5: Please refer to Figures 4 to 5 :

[0067] This invention proposes a rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in shallow-buried tunnels, comprising:

[0068] Cast-in-place pile 5 is a reinforced concrete cast-in-place structure, and cast-in-place pile 5 includes:

[0069] The support cage body 501 is a cylindrical cage structure. The center of the support cage body 501 is an inner support rod 5012, and the outer side of the support cage body 501 is an outer support rod 5011 arranged in a circular array. The support cage body 501 is provided with multiple pieces, and the multiple support cage bodies 501 are installed vertically.

[0070] Rotating shaft 502 is rotatably connected to the top of the support cage body 501;

[0071] In this embodiment of the disclosure, such as Figure 7 As shown, the bottom of the support cage body 501 is provided with a circular array of multiple sets of threaded holes, and the top of the support cage body 501 is provided with a circular array of light holes. The threaded hole of the bottom support cage body 501 is bolted to a bottom stabilizing nail 510. The lower support cage body 501 is connected to the threaded hole of the upper support cage body 501 by connecting bolts 509 inserted into the light hole. The top support cage body 501 is connected to the crown beam 7 by the light hole. This achieves universality of threaded holes, which can realize both bottom fixed support and connection between support cage bodies 501, with good versatility and improved ease of use.

[0072] Example 6: Please refer to Figures 3 to 11 :

[0073] This invention proposes a rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in shallow-buried tunnels, comprising:

[0074] Bottom stabilizing nails 510 are arranged in a circumferential array at the bottom of the support cage body 501;

[0075] Side stabilizing nails 507 are provided in multiple sets, and each set of side stabilizing nails 507 is arranged in a circumferential array with multiple pieces.

[0076] The side nail drive assembly is located inside the support cage body 501.

[0077] In this embodiment of the disclosure, such as Figure 11 As shown, the side nail drive assembly includes:

[0078] Drive thread 5021 is coaxially and fixedly connected to the rear of rotating shaft 502;

[0079] The swing drive slider 503 is slidably connected to the top of the uppermost support cage body 501. The swing drive slider 503 and the drive thread 5021 are threaded together to form a screw and nut transmission pair. In use, when the rotating shaft 502 is rotated, the rotating shaft 502 drives the swing drive slider 503 to slide through the screw and nut transmission pair formed by the swing drive slider 503 and the drive thread 5021.

[0080] In this embodiment of the disclosure, such as Figure 11 As shown, the side nail drive assembly also includes:

[0081] The swing link 504 is hinged to the end of the swing drive slider 503;

[0082] The intermediate rotating shaft 505 is rotatably connected inside the inner support rod 5012. The other end of the swing connecting rod 504 is hinged to the intermediate rotating shaft 505. The swing drive slider 503, the swing connecting rod 504, the intermediate rotating shaft 505 and the support cage body 501 together form a crank slider transmission structure. In use, when the swing drive slider 503 slides, the swing drive slider 503 drives the intermediate rotating shaft 505 to swing through the crank slider transmission structure formed by the swing drive slider 503, the swing connecting rod 504, the intermediate rotating shaft 505 and the support cage body 501.

[0083] In this embodiment of the disclosure, such as Figure 6 As shown, the side nail drive assembly also includes:

[0084] The swing arm 506 is rotatably connected to the outside of the inner support rod 5012;

[0085] The swing connector 601 is located on the top of the swing arm 506 and is plugged into the intermediate rotating shaft 505. In use, when the intermediate rotating shaft 505 swings, the intermediate rotating shaft 505 drives the swing arm 506 to swing through the swing connector 601.

[0086] In this embodiment of the disclosure, such as Figure 7 As shown, the side nail drive assembly also includes:

[0087] The swing assembly 508 is evenly arranged on the outside of the outer support rod 5011 for rotational connection;

[0088] The side stabilizing pin 507 is hinged to the outside of the swing arm 506 and slidably connected to the swing assembly 508. The swing arm 506, the swing assembly 508, the side stabilizing pin 507, and the support cage body 501 together form a crank-slider transmission mechanism. In use, when the swing arm 506 swings, the swing arm 506 drives the side stabilizing pin 507 to slide through the crank-slider transmission mechanism formed by the swing arm 506, the swing assembly 508, the side stabilizing pin 507, and the support cage body 501, thereby realizing the extension and retraction of the side stabilizing pin 507. This meets the needs of casting piles 5 of different sizes. At the same time, the side stabilizing pin 507 can also be inserted tightly into the central rock column 3 to improve the connection stability between the cast-in-place pile 5 and the central rock column 3.

[0089] In this embodiment of the disclosure, such as Figures 9-10 As shown, the top of the intermediate rotating shaft 505 is provided with an upper connecting part 5052, which has a groove structure, and the bottom of the intermediate rotating shaft 505 is provided with a lower connecting part 5051, which has a protruding structure. The upper and lower intermediate rotating shafts 505 are connected by the upper connecting part 5052 and the lower connecting part 5051. In use, when the upper intermediate rotating shaft 505 rotates, the upper intermediate rotating shaft 505 drives the lower intermediate rotating shaft 505 to rotate synchronously through the upper connecting part 5052 and the lower connecting part 5051.

[0090] The working principle of this embodiment:

[0091] A certain tunnel consists of a right-line small-section tunnel 1 and a left-line small-section tunnel 2 intersecting at a large-section tunnel 4. At the intersection, the large-section tunnel 4 (N section, area 143㎡) branches into two equal-section, narrow-clearance intersecting chambers (right-line small-section tunnel 1 and left-line small-section tunnel 2) (area 39㎡). The narrow-clearance section between the right-line small-section tunnel 1 and the left-line small-section tunnel 2 is as long as 55m. The narrowest point of the rock pillar 3 in the two intersecting chambers is only 1m wide. During construction, cast-in-place piles 5 with a diameter of Φ0.6m and a spacing of 2-4m are added along the central rock pillar 3 in the shallow buried section of the narrow-clearance tunnel. The bottom elevation of the piles is 3-4.5m lower than the invert of the main tunnel. A capping beam 7 is installed at the top of the cast-in-place piles 5 to connect them. Overall, during the initial support arch frame construction, the anchor pipes 6 on the side closest to the central rock column 3 are anchored into the cast-in-place piles 5. Specifically: when the width of the central rock column 3 is 1-2m, the cast-in-place piles 5 are distributed along the center of the central rock column 3; when the width of the central rock column 3 is greater than 2m and less than 4m, the cast-in-place piles 5 are staggered along the length of the central rock column 3, close to both sides of the central rock column 3, with the distance between the cast-in-place piles 5 and both sides of the central rock column 3 being 0.2-1m. The anchor pipes 6 corresponding to the location of the cast-in-place piles 5 are anchored into the cast-in-place piles 5. Each side of each cast-in-place pile 5 is anchored with three anchor pipes 6, and the anchor pipes 6 on both sides of the three anchor pipes 6 are inclined and anchored into the cast-in-place piles 5 in a staggered direction.

[0092] During the construction of the cast-in-place pile 5, according to the actual required depth of the cast-in-place pile 5, the main body of the support cage 501 is connected end to end and connected by connecting bolts 509. Then, the main body of the support cage 501 is placed into the pile pit. The rotating shaft 502 is rotated by a tool. The rotating shaft 502 drives the swing driving slider 503 to slide through a screw-nut transmission pair consisting of a swing driving slider 503 and a drive thread 5021. The swing driving slider 503 drives the intermediate rotating shaft 505 to swing through a crank-slider transmission structure consisting of the swing driving slider 503, the swing connecting rod 504, the intermediate rotating shaft 505, and the main body of the support cage 501. The intermediate rotating shaft 505 drives the swing arm 50 through the swing connecting piece 601. 6. The swing arm 506 drives the side stabilizing nail 507 to slide through the crank-slider transmission mechanism composed of the swing arm 506, the swing kit 508, the side stabilizing nail 507 and the support cage body 501. The side stabilizing nail 507 extends out and touches the pit wall, thereby adjusting the support cage body 501 so that the support cage body 501 is in the center position. Then, the support cage body 501 is tamped down and pressed into the pile pit. The rotating shaft 502 is tightened so that the side stabilizing nail 507 is in close contact with the pit wall, ensuring the connection stability between the cast-in-place pile 5 and the central rock column 3. The support cage body 501 is connected to the crown beam 7 steel reinforcement through the light hole at the top. Then, mortar is poured in to form the cast-in-place pile 5.

[0093] The following points should be noted in this article:

[0094] 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in general design.

[0095] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0096] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A rock pillar reinforcement device for abrupt transitions from a large cross-section to a small cross-section in shallow tunnels, characterized in that, include: Cast-in-place piles (5) are installed along the central rock column (3) in the shallow buried section of the tunnel with small clearance. Cast-in-place piles (5) are installed along the tunnel length direction on the outside of the two small cross-section tunnels. Crown beam (7), which is fixed to the top of the cast-in-place pile (5) and is integrated with the cast-in-place pile (5); Locking foot anchor pipe (6), the locking foot anchor pipe (6) passes through the small section tunnel wall and is anchored to the cast-in-place pile (5); The cast-in-place pile (5) is a reinforced concrete cast-in-place structure, and the cast-in-place pile (5) includes: The support cage body (501) is a cylindrical cage structure. The center of the support cage body (501) is an inner support rod (5012), and the outer side of the support cage body (501) is an outer support rod (5011) arranged in a circular array. The support cage body (501) is provided with multiple pieces, and the multiple support cage bodies (501) are installed vertically. A rotating shaft (502) is rotatably connected to the top of the support cage body (501); Bottom stabilizing nails (510) are arranged in a circumferential array at the bottom of the support cage body (501); Side stabilizing nails (507), wherein multiple sets of side stabilizing nails (507) are provided, and multiple pieces of side stabilizing nails (507) are arranged in a circumferential array in each set; A side nail drive assembly is disposed inside the support cage body (501).

2. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow-buried tunnel according to claim 1, characterized in that, The diameter of the cast-in-place pile (5) is Φ0.6-0.8m, the spacing between the cast-in-place piles (5) is 2-4m, and the bottom elevation of the cast-in-place pile (5) is 3-4.5m lower than the invert arch of the tunnel.

3. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow-buried tunnel according to claim 1, characterized in that, When the width of the central rock column (3) is 1-2m, the cast-in-place piles (5) inside the central rock column (3) are distributed along the center of the central rock column (3); when the width of the central rock column (3) is greater than 2m and less than 4m, the cast-in-place piles (5) inside the central rock column (3) are arranged alternately along the length direction of the central rock column (3) and close to both sides of the central rock column (3), and the distance between the cast-in-place piles (5) and both sides of the central rock column (3) is 0.2-1m.

4. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 1, characterized in that, The anchor pipe (6) at the location of the cast-in-place pile (5) is anchored into the cast-in-place pile (5). Each cast-in-place pile (5) in the middle rock column (3) has three anchor pipes (6) anchored into one side, and the two anchor pipes (6) on both sides of the three anchor pipes (6) are anchored into the cast-in-place pile (5) in an intersecting direction.

5. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 1, characterized in that, The bottom circumferential array of the support cage body (501) is provided with multiple sets of threaded holes, and the top of the support cage body (501) is provided with a circumferential array of light holes. The threaded hole of the bottom support cage body (501) is bolted to a bottom stabilizing nail (510). The lower support cage body (501) is inserted into the light hole through a connecting bolt (509) and connected to the threaded hole of the upper support cage body (501). The top support cage body (501) is connected to the crown beam (7) through the light hole.

6. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 1, characterized in that, The side nail transmission assembly includes: The drive thread (5021) is coaxially and fixedly connected to the rear of the rotating shaft (502); The swing drive slider (503) is slidably connected to the top of the uppermost support cage body (501). The swing drive slider (503) and the drive thread (5021) are threaded together to form a lead screw and nut transmission pair.

7. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 6, characterized in that, The side nail drive assembly also includes: A swing link (504) is hinged to the end of the swing drive slider (503); The intermediate rotating shaft (505) is rotatably connected inside the inner support rod (5012). The other end of the swing connecting rod (504) is hinged to the intermediate rotating shaft (505). The swing drive slider (503), the swing connecting rod (504), the intermediate rotating shaft (505) and the support cage body (501) together constitute the crank slider transmission structure.

8. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 7, characterized in that, The side nail drive assembly also includes: A swing arm (506) is rotatably connected to the outside of the inner support rod (5012); A swing connector (601) is provided on the top of the swing arm (506) and is plugged into the intermediate rotating shaft (505).

9. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 8, characterized in that, The side nail drive assembly also includes: The swing assembly (508) is evenly arranged on the outside of the outer support rod (5011) for rotational connection; The side stabilizing pin (507) is hinged to the outside of the swing arm (506). The side stabilizing pin (507) is slidably connected to the swing assembly (508). The swing arm (506), the swing assembly (508), the side stabilizing pin (507) and the support cage body (501) together constitute the crank-slider transmission mechanism.

10. The rock pillar reinforcement device for the abrupt transition from a large to a small cross-section in a shallow tunnel according to claim 7, characterized in that, The top of the intermediate rotating shaft (505) is provided with an upper connecting part (5052), which has a groove structure. The bottom of the intermediate rotating shaft (505) is provided with a lower connecting part (5051), which has a protruding structure. The upper and lower intermediate rotating shafts (505) are connected by inserting the upper connecting part (5052) and the lower connecting part (5051).

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