Methods for controlling deformation and preventing collapse at intersections of tunnels and vehicular tunnels in high-stress soft rock deformation tunnels

Abstract

This invention belongs to the field of tunnel construction, specifically relating to a method for controlling deformation and preventing collapse at the intersection of a vehicular tunnel and a tunnel under high ground stress in soft rock. The method includes the following steps: excavating the main tunnel and constructing initial support; installing a support ring beam and a ground beam at the reserved opening of the vehicular tunnel in the main tunnel, with the support ring beam, ground beam, and initial support fixedly connected; installing a reserved pipe for a vehicular tunnel pipe roof inside the support ring beam; installing a pipe roof in the direction of the vehicular tunnel, with the reserved pipe fixedly connected; installing a reinforcing cage inside the pipe roof and grouting it; performing secondary lining of the main tunnel; removing the initial support between the support ring beam and the ground beam; excavating the vehicular tunnel and performing secondary lining of the vehicular tunnel. This method improves the stress system at the intersection of the main tunnel and the vehicular tunnel, enhancing the structural stability and construction safety at this intersection.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction, specifically relating to a method for controlling deformation and preventing collapse at the intersection of a vehicular tunnel in a high-stress soft rock deformation tunnel. Background Technology

[0002] The construction of vehicular passageways between the tunnels on highways involves large excavation sections and complex stresses at the intersection of the main tunnel and the vehicular passageway. In areas with poor geological conditions, improper handling can lead to deformation of the surrounding rock or even collapse. Existing designs lack specific and detailed designs, resulting in high construction safety risks at the tunnel entrances.

[0003] The traditional construction procedure for a vehicular tunnel is as follows: After the initial support of the main tunnel is excavated, the distance between the tunnel face and the intersection of the main tunnel and the vehicular tunnel is greater than 30m, and sufficient space is available before the vehicular tunnel excavation begins. Anchor pipes are installed 30cm above the cut-off point of the steel frame of the initial support of the main tunnel. Then, the steel frame within the vehicular tunnel area is cut off and dismantled (without sprayed concrete). This disrupts the closed-loop stress system of the initial support of the main tunnel. Due to the relaxation of the surrounding rock and the effect of ground stress, the initial support of the main tunnel deforms and cracks. Combined with the excavation of the vehicular tunnel, this results in a relatively larger excavation span for the main tunnel, leading to increased deformation of the initial support or causing instability and collapse above the intersection. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a method for controlling deformation and preventing collapse at the intersection of the main tunnel and the vehicular tunnel in high-stress soft rock. This method improves the stress system at the intersection of the main tunnel and the vehicular tunnel, and enhances the stability of the structure and the safety of construction at the intersection.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for controlling deformation and preventing collapse at the intersection of a vehicular tunnel in high-stress soft rock deformation tunnel includes the following steps:

[0007] S1. Excavate the main tunnel and provide initial support for the main tunnel;

[0008] S2. A support ring beam and a ground beam are set at the reserved opening of the main tunnel. The support ring beam, the ground beam and the initial support are fixedly connected. The reserved pipe of the tunnel pipe roof is set inside the support ring beam.

[0009] S3. A pipe roof is installed in the direction of the tunnel, and the pipe roof is fixedly connected to the reserved pipe. A steel cage is installed in the pipe roof and grout is injected.

[0010] S4. Secondary lining of the main tunnel;

[0011] S5. Remove the initial support between the supporting ring beam and the ground beam, excavate the tunnel and carry out secondary lining of the tunnel.

[0012] The initial support described in S1 is a steel frame.

[0013] The initial support described in S1 is equipped with a flange structure, which is located on the inner surface of the support ring beam and the upper surface of the ground beam.

[0014] The flange structure is located inside the junction box.

[0015] The specific manufacturing process of the support ring beam described in S2 is as follows: two adjacent steel frames are welded together using I-beams to form the support ring beam.

[0016] The ground beam described in S2 is located at the bottom of the reserved opening of the main tunnel's vehicular tunnel, and the supporting ring beam and steel frame are all fixedly connected to the ground beam.

[0017] The construction process of the ground beam is as follows: after the bottom of the main tunnel is excavated, the closed-loop steel frame at the bottom of the tunnel is installed, and the reinforced concrete ground beam is poured at the reserved opening between the main tunnel and the vehicular tunnel.

[0018] The secondary lining of the main tunnel as described in S4 specifically involves: tying reinforcing bars and pouring concrete inside the main tunnel; the reserved opening between the main tunnel and the vehicle tunnel requires a single slab and no construction joints are allowed.

[0019] The specific process for removing the initial support between the support ring beam and the ground beam as described in S5 is as follows: use a cutting machine to cut open the secondary lining of the initial tunnel along the outline of the tunnel, open the joint box, and remove the flange structure and the steel frame between the support ring beam and the ground beam.

[0020] The specific process of excavating and lining the vehicular tunnel described in S5 is as follows: the vehicular tunnel is excavated using mechanical chiseling method while the initial support of the vehicular tunnel is completed. After the vehicular tunnel excavation and support are completed for 8m, the invert arch and invert arch filling are constructed in a timely manner, and then the secondary lining of the vehicular tunnel is constructed to complete the lock at the intersection of the main tunnel and the vehicular tunnel.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The method of this invention includes: excavating the main tunnel and providing initial support; installing a support ring beam and a ground beam at the reserved opening of the vehicular tunnel in the main tunnel, with the support ring beam, ground beam, and initial support fixedly connected. The installation of the support ring beam enhances the stability of the intersection of the main tunnel and the vehicular tunnel, and the fixed connection of the support ring beam, ground beam, and initial support improves the stress system at the intersection of the main tunnel and the vehicular tunnel, thereby increasing the structural stability and construction safety at the intersection. A reserved pipe for the vehicular tunnel is installed inside the support ring beam, further enhancing the structural stability at the intersection of the main tunnel and the vehicular tunnel. A pipe roof is installed in the direction of the vehicular tunnel, with the reserved pipe fixedly connected. A reinforcing cage is installed inside the pipe roof of the vehicular tunnel and grouting is performed, further enhancing the stability of the vehicular tunnel and construction safety. Secondary lining is then performed on the main tunnel, further enhancing the structural stability of the main tunnel. After removing the initial support between the supporting ring beam and the ground beam, and ensuring the stability of the main tunnel and the structure at the intersection of the main tunnel and the vehicular tunnel, the initial support between the supporting ring beam and the ground beam is removed to ensure the safety of construction. Finally, the vehicular tunnel is excavated and the secondary lining of the vehicular tunnel is carried out.

[0023] Furthermore, the initial support is equipped with a flange structure located on the inner surface of the support ring beam and the upper surface of the ground beam. The flange structure facilitates the removal of the initial support between the support ring beam and the ground beam in the later stage, thereby improving construction efficiency.

[0024] Furthermore, the specific fabrication process of the support ring beam is as follows: two adjacent steel frames are welded together using I-beams to form a support ring beam. At the same time, the steel frames at the intersection of the main tunnel and the vehicular tunnel are fixedly connected to each other through the support ring beam, which enhances the stability of the structure at the intersection of the main tunnel and the vehicular tunnel and improves the safety of construction. Attached Figure Description

[0025] Figure 1 This is a diagram of the overall construction structure of the present invention;

[0026] Figure 2 This is a diagram showing the overall construction structure of the invention and the location relationship between the unstable area at the intersection;

[0027] Figure 3 This is a schematic diagram of the supporting ring beam and ground beam structure of the present invention;

[0028] Figure 4 This is a schematic diagram of the supporting ring beam structure of the present invention;

[0029] Figure 5 This is a schematic diagram of the initial support and flange structure of the present invention.

[0030] Among them, 1. Initial support; 2. Flange structure; 3. Support ring beam; 4. Ground beam; 5. Junction box; 6. Pipe roof reserved pipe; 7. Pipe roof; 8. Main tunnel; 9. Vehicle tunnel; 10. Invert arch; 11. Invert arch filling; 12. Main tunnel secondary lining; 13. Vehicle tunnel initial support; 14. Vehicle tunnel secondary lining; 15. Unstable area at the intersection. Detailed Implementation

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] A method for controlling deformation and preventing collapse at the intersection of a vehicular tunnel in high-stress soft rock deformation tunnel includes the following steps:

[0033] S1. As Figure 1 As shown, the main tunnel 8 was excavated and the initial support 1 for the main tunnel 8 was completed;

[0034] The initial support 1 is a steel frame.

[0035] Preferably, the initial support 1 is provided with a flange structure 2, the flange structure 2 as follows: Figure 5 As shown, flange structure 2 is located on the inner surface of support ring beam 3 and the upper surface of ground beam 4, as... Figure 3 and Figure 4 As shown. The flange structure 2 facilitates the removal of the initial support 1 between the supporting ring beam 3 and the ground beam 4, improving construction efficiency. Furthermore, the original support system of the main tunnel 8 does not need to be changed when removing the initial support 1 between the supporting ring beam 3 and the ground beam 4.

[0036] Furthermore, such as Figure 3 , Figure 4 and Figure 5 As shown, each flange structure 2 consists of two flanges, which are fixedly connected to the upper and lower initial supports 1 respectively, and the two flanges are connected by bolts.

[0037] Preferred, such as Figure 5 As shown, the flange structure 2 is installed inside the junction box 5, which is filled with foam adhesive to prevent the flange structure 2 from being wrapped by sprayed concrete during secondary lining, which would make it difficult to remove the steel frame between the support ring beam 3 and the ground beam 4, thus further improving the efficiency of construction.

[0038] S2. For example Figure 2 As shown, a support ring beam 3 and a ground beam 4 are set at the reserved opening of the vehicle tunnel 9 in the main tunnel 8. The support ring beam 3, the ground beam 4 and the initial support 1 are fixedly connected. The reserved pipe 6 of the vehicle tunnel 9 is set inside the support ring beam 3.

[0039] Furthermore, the supporting ring beam 3 is located within the initial support outline of the tunnel 9 and cannot encroach upon the area of ​​the tunnel 9.

[0040] The specific manufacturing process of the supporting ring beam 3 is as follows: two adjacent steel frames are welded together to form the supporting ring beam 3 using I-beams. The I-beams are specifically 120 I-beams.

[0041] Ground beam 4 is located at the bottom of the reserved opening of the vehicle passage 9 in the main tunnel 8. The supporting ring beam 3 and the steel frame are all fixedly connected to ground beam 4. When the steel frame of the main tunnel 8 is dismantled, ground beam 4 acts as a closed loop with the supporting ring beam 3, enhancing the stability of the structure.

[0042] The construction process of ground beam 4 is as follows: After the bottom of the main tunnel 8 is excavated, the closed-loop steel frame at the bottom of the tunnel is installed, and the reinforced concrete ground beam 4 is poured at the reserved opening between the main tunnel 8 and the vehicular tunnel 9.

[0043] S3. A pipe roof 7 is installed in the direction of the tunnel 9. The pipe roof 7 is fixedly connected to the reserved pipe 6 of the pipe roof. A steel cage is installed inside the pipe roof 7 and grout is injected. The specific process is as follows:

[0044] Drilling was carried out along the direction of tunnel 9 using a drilling rig, and pipe roof 7 was installed. Pipe roof 7 was made of Φ108 steel pipe and reinforced with a steel cage. Grouting was injected into the inside of pipe roof 7 to consolidate and reinforce the surrounding rock and the tunnel. The tail of pipe roof 7 was connected to the reserved pipe 6 of pipe roof, forming a support beam structure system with the support ring beam 3, which simultaneously controlled the deformation of the main tunnel 8 and tunnel 9.

[0045] S4. Secondary lining of main tunnel 8;

[0046] The secondary lining of the main tunnel 8 is specifically carried out by tying steel bars inside the main tunnel 8 and pouring concrete to form the secondary lining 12 of the main tunnel. The reserved opening between the main tunnel 8 and the vehicle tunnel 9 requires a whole slab and no construction joints can be set.

[0047] S5. After the secondary lining of the main tunnel 8 reaches the design strength, the initial support 1 between the supporting ring beam 3 and the ground beam 4 is removed, and the vehicular tunnel 9 is excavated and the secondary lining of the vehicular tunnel 9 is carried out.

[0048] The specific process of removing the initial support 1 between the supporting ring beam 3 and the ground beam 4 is as follows: use a cutting machine to cut open the secondary lining of the initial tunnel 8 along the outline of the vehicle tunnel 9, open the joint box 5, and remove the flange structure 2 and the steel frame between the supporting ring beam 3 and the ground beam 4.

[0049] The specific process of excavating and lining the secondary tunnel of the vehicular tunnel 9 is as follows: the vehicular tunnel 9 is excavated by mechanical chiseling and the initial support 13 of the vehicular tunnel is completed at the same time. After the excavation and support of the vehicular tunnel 9 is completed for 8m, the invert arch 10 is constructed and the invert arch 10 is filled in a timely manner. Then the secondary lining of the vehicular tunnel 9 is carried out to complete the lock at the intersection of the main tunnel 8 and the vehicular tunnel 9.

[0050] Preferably, the method of the present invention includes: excavating the main tunnel 8 and constructing initial support 1 for the main tunnel 8; setting up a support ring beam 3 and a ground beam 4 at the reserved opening of the vehicular tunnel 9 in the main tunnel 8; the support ring beam 3, the ground beam 4, and the initial support 1 are fixedly connected; the setting of the support ring beam 3 enhances the stability of the intersection of the main tunnel 8 and the vehicular tunnel 9; the support ring beam 3 and the ground beam 4 form a closed loop; the fixed connection of the support ring beam 3, the ground beam 4, and the initial support 1 improves the stress system at the intersection of the main tunnel 8 and the vehicular tunnel 9, thereby improving the structural stability and construction safety at the intersection of the main tunnel 8 and the vehicular tunnel 9. A reserved pipe 6 for the vehicular tunnel 9 pipe roof is installed inside the support ring beam 3; the reserved pipe 6 is used to install the pipe roof 7 of the vehicular tunnel 9, enhancing the structural stability at the intersection of the main tunnel 8 and the vehicular tunnel 9. A reinforcing cage is installed inside the pipe roof 7 of the vehicular tunnel 9 and grouting is performed, further enhancing the stability and construction safety of the vehicular tunnel 9. Secondary lining was carried out on main tunnel 8 to further enhance the stability of its structure. After ensuring the stability of the structures of main tunnel 8, vehicular tunnel 9, and the intersection of main tunnel 8 and vehicular tunnel 9, the initial support 1 between the supporting ring beam 3 and the ground beam 4 was removed to ensure construction safety. Finally, vehicular tunnel 9 was excavated, and the initial support 13 and secondary lining 14 of the vehicular tunnel were completed. Figure 1 As shown.

[0051] Preferably, the method of the present invention is based on the structural stress system and variable control, resulting in a more scientific construction organization and lower construction safety risks.

[0052] Example:

[0053] The Yongfeng Tunnel on the G544 Shuangjiu Highway is composed of carbonaceous slate interbedded with phyllite geology. The measured maximum ground stress is 18.2 MPa, classifying it as a medium-deformation tunnel.

[0054] Using traditional methods, after the main tunnel 8 is constructed to the position of the vehicular tunnel 9, the vehicular tunnel 9 is reserved. At this point, the steel frame is not shotcreted. Figure 2 As shown, due to the unstable area 15 at the intersection, construction of tunnel 9 began half a month later. At this time, the steel frame within tunnel 9 experienced twisting deformation, with some steel frames breaking. The maximum deformation of the initial support of the main tunnel was 36.2 cm. The initial support of the main tunnel 8, constructed using traditional methods within tunnel 9, also experienced steel frame twisting failure. Traditional construction procedures and control measures failed to meet requirements, resulting in significant construction risks.

[0055] After adopting the method of this invention, the maximum deformation of the main tunnel 8 was 15mm, and the construction deformation at the intersection was 17.5mm, both within the design deformation range, and all quality indicators met the specifications.

[0056] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high ground stress soft rock deformation tunnel vehicle tunnel intersection deformation control anti-collapse method, characterized in that, It comprises the following steps: S1. The main hole (8) is excavated and the initial support (1) of the main hole (8) is prepared; The initial support (1) in S1 is a steel frame; The flange structure (2) is arranged on the initial support (1) in S1, and the flange structure (2) is located on the inner surface of the support ring beam (3) and the upper surface of the ground beam (4); S2. The support ring beam (3) and the ground beam (4) are arranged at the reserved opening of the vehicle tunnel (9) of the main hole (8), and the support ring beam (3), the ground beam (4) and the initial support (1) are fixedly connected, and the support ring beam (3) is internally provided with a vehicle tunnel (9) pipe shed reserved pipe (6); The specific manufacturing process of the support ring beam (3) in S2 is that the adjacent two steel frames are welded through an I-beam to form a support ring beam (3); The ground beam (4) in S2 is located at the bottom surface of the reserved opening of the vehicle tunnel (9) of the main hole (8), and the support ring beam (3) and the steel frame are fixedly connected with the ground beam (4); The construction process of the ground beam (4) is that after the main hole (8) tunnel bottom is excavated, the tunnel bottom closed loop steel frame is installed, and the reinforced concrete ground beam (4) is poured at the reserved opening of the main hole (8) and the vehicle tunnel (9); S3. A pipe shed (7) is arranged in the direction of the vehicle tunnel (9), the pipe shed (7) is fixedly connected with the pipe shed reserved pipe (6), a steel reinforcement cage is arranged in the pipe shed (7) and grouting is performed; S4. The main hole (8) is subjected to secondary lining; S5. The initial support (1) between the support ring beam (3) and the ground beam (4) is removed, the vehicle tunnel (9) is excavated and subjected to secondary lining.

2. The high ground stress soft rock deformation tunnel vehicle tunnel intersection deformation control anti-collapse method according to claim 1, characterized in that, The flange structure (2) is arranged in the joint box (5).

3. The high ground stress soft rock deformation tunnel vehicle tunnel intersection deformation control anti-collapse method according to claim 1, characterized in that, The secondary lining of the main hole (8) in S4 is that steel reinforcement is measured and bound in the main hole (8) and concrete is poured, and the reserved opening of the main hole (8) and the vehicle tunnel (9) requires an integral plate and cannot be provided with a construction joint.

4. The high ground stress soft rock deformation tunnel car tunnel intersection deformation control anti-collapse method of claim 2, wherein, The specific process of removing the initial support (1) between the support ring beam (3) and the ground beam (4) in S5 is that a cutting machine is used to cut the secondary lining of the main hole (8) along the contour line of the vehicle tunnel (9), the joint box (5) is opened, the flange structure (2) and the steel frame between the support ring beam (3) and the ground beam (4) are removed.

5. The high ground stress soft rock deformation tunnel car tunnel intersection deformation control anti-collapse method of claim 1, wherein, The specific process of excavating the vehicle tunnel (9) and performing secondary lining of the vehicle tunnel (9) in S5 is that the vehicle tunnel (9) is excavated by mechanical chiseling and the vehicle tunnel initial support (13) is simultaneously completed, after the vehicle tunnel (9) excavation support is completed for 8m, the inverted arch (10) and the inverted arch (10) filling are promptly constructed, then the secondary lining of the vehicle tunnel (9) is constructed, and the lock joint at the intersection of the main hole (8) and the vehicle tunnel (9) is completed.

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