A safe construction method for T-shaped intersections in super-large cross-section tunnels

Abstract

The invention discloses a safe construction method for a super-large section tunnel T-intersection, which relates to the technical field of tunnel construction. The technical scheme thereof includes the following steps: S1: excavating the left and right guide pits of the super-large section of the connecting road by using a double-side wall guide pit construction method; S2: excavating the main channel slope in the guide pit on the leading side of the connecting road; S3: excavating the main channel slope in the guide pit on the trailing side of the connecting road; S4: performing initial support on the main channels on both sides, and then excavating the middle interlayer rock of the connecting road after the full section of the support is closed; S5: constructing the connecting road invert and arch wall; S6: using the portal frame and full-frame support system of the T-channel and the combined steel mold to construct the secondary lining arch wall structure of the T-intersection; the secondary lining structure in S6 is provided with a steel arch frame. The construction method solves the problems of extended construction period and high cost under the premise of ensuring the safety of the construction of the super-large section tunnel T-intersection.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and more specifically to a safe construction method for a T-shaped intersection in a tunnel with a super-large cross-section. Background Art

[0002] The double-side wall pilot tunnel method is almost always used in large-section tunnel construction. The double-side wall pilot tunnel method is a construction technology that supports while excavating. The principle is: the entire large tunnel section is divided into three small sections, left, middle and right, by two middle partition walls. The left and right pilot tunnels are constructed first, followed by the middle section. After the initial support arch is formed into a ring, the temporary supports of the pilot tunnels on both sides are removed to form a full section. After the surrounding rock is stable, the secondary lining is applied. The pilot tunnels on both sides of the double-side wall pilot tunnel method are inverted goose egg shapes. Each block can be closed into a ring after excavation, which is conducive to controlling deformation.

[0003] The safest construction method for tunnel intersection construction is to break into another tunnel after the secondary lining is completed. Due to the relative safety distance between the steps of the double-side wall construction, it takes a long time to break after the secondary lining is completed. Especially for T-shaped intersection construction (digging from a straight line to both sides), if the tunnels on both sides are excavated after the secondary lining is completed, it will inevitably cause a long period of time when the tunnel excavation and primary support cannot be carried out, resulting in the inability to form a reasonable flow of operations for each process, resulting in extended construction period and high costs. Summary of the invention

[0004] The purpose of the present invention is to provide a safe construction method for a super-large cross-section tunnel T-intersection, which solves the problems of extended construction period and high cost while ensuring the safety of the super-large cross-section tunnel T-intersection construction.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A safe construction method for a super-large cross-section tunnel T-intersection, specifically comprising the following steps:

[0006] S1: Double side wall pilot tunnel construction method is used to excavate the left and right side pilot tunnels of the super large section of the connecting road;

[0007] S2: Excavation of the main channel slope in the pilot pit on the leading side of the connecting road;

[0008] S3: Excavation of the main channel slope in the guide pit on the rear side of the connecting road;

[0009] S4: Initial support is carried out on the main channels on both sides, and after the full section of the support is closed, the middle rock of the connecting channel is excavated;

[0010] S5: Construction of the connecting road invert and arch wall;

[0011] S6: Use the portal frame of the T-channel plus the full-frame support system to construct the secondary lining arch wall structure of the T-intersection;

[0012] A steel arch frame is provided inside the secondary lining structure in S6.

[0013] Furthermore: the connecting roads in the left and right guide pits and the openings of the main passage are set with supporting beams.

[0014] Furthermore: the connecting channel is a IVd type tunnel, and the main channel is a IVb type tunnel.

[0015] Further: the length of the middle rock of the connecting road in S4 is 25m.

[0016] Furthermore: during the construction of the secondary lining structure in S6, concrete pouring of the rear arch of the side wall is required in sequence.

[0017] In summary, the present invention has the following beneficial effects:

[0018] 1. This method makes the connection between cross tunnel excavation and primary support, drainage and secondary lining more reasonable, speeding up the construction progress and reducing costs;

[0019] 2. This method can not only ensure the continuous operation of tunnel excavation and primary support, but also ensure the follow-up construction of drainage and secondary lining, so that the progress of the entire tunnel project will not be greatly affected by the construction of super-large section T-intersections, breaking through the bottleneck of the construction of super-large section T-intersections in tunnels that has a great impact on the construction period;

[0020] 3. While retaining the interlayer rock in the super-large section of the connecting road, using the left and right pilot pits to advance to the main channels on both sides can make the construction rhythm of subsequent processes of the tunnel more reasonable;

[0021] 4. When constructing the secondary lining structure at the intersection, a portal frame with a T-shaped channel and a full-frame support system are used, so that the secondary lining construction will not affect the tunnel excavation in front;

[0022] 5. When the connecting road is converted to the main channel, the middle interlayer of 25m of the connecting road super-large section at the T-shaped intersection of the connecting road and the main channel is retained. The length of the retained middle interlayer exceeds the width of the main channel section by about 5m, which effectively suppresses the convergence effect of the surrounding rock disturbance during the excavation process of the connecting road super-large section to the main channel openings on both sides;

[0023] 6. Adding a steel arch frame in the secondary lining can serve as a load-bearing point for the super-large section secondary lining of the connecting road in the direction of the main channel, and can also increase the overall stiffness and stability of the secondary lining at the T-intersection, greatly improving construction safety and structural safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1is a plan view of a T-shaped intersection according to an embodiment of the present invention;

[0025] Figure 2 yes Figure 1 The cross-section at 1-1 in the middle;

[0026] Figure 3 is a structural diagram of the main opening of a T-shaped intersection in an embodiment of the present invention;

[0027] Figure 4 This is a cross-sectional structural diagram of the main opening of a T-shaped intersection in an embodiment of the present invention;

[0028] Figure 5 It is a layout diagram of the arch frame in the second lining of the intersection in an embodiment of the present invention;

[0029] Figure 6 It is a plan layout diagram of the secondary lining support system of the intersection in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-6 The present invention is described in further detail.

[0031] Embodiment: A safe construction method for a super-large cross-section tunnel T-intersection, such as Figures 1 to 6 As shown, the specific steps include:

[0032] S1: Double side wall pilot tunnel construction method is used to excavate the left and right side pilot tunnels of the super large section of the connecting road, such as Figure 3 As shown, the connecting paths in the left and right guide pits and the openings of the main passage are set with support beams;

[0033] S2: Excavation of the main channel slope in the pilot pit on the leading side of the connecting road;

[0034] S3: Excavate the main channel slope in the guide pit on the rear side of the connecting road. The connecting road is a type IVd tunnel;

[0035] S4: Initial support is provided for the main channels on both sides. After the entire support section is closed, the middle rock of the connecting channel is excavated. The main channel is a Type IVb tunnel with a middle rock length of 25m, and the length of the middle rock spans the cross-sectional width of the main channel by about 5m. This effectively suppresses the convergence effect of the surrounding rock disturbance during the excavation process of the connecting channel with a super-large cross-section to the main channels on both sides.

[0036] S5: Construction of the connecting road invert and arch wall; the specific operation method of the construction is to first carry out initial support for the middle rock invert, and after completion, close the entire section of the initial support of the tunnel into a ring, and determine the stability of the surrounding rock deformation based on the monitoring measurement data, and then gradually remove the temporary supports on both sides of the invert; in this embodiment, a steel trestle is set up for passage when the invert secondary lining structure is constructed, and then a portal frame, a full-frame support system and a combined steel mold are constructed for the large-section secondary lining arch wall of the connecting road;

[0037] S6: The portal frame and full-frame support system of the T-shaped channel and the combined steel formwork are used to construct the secondary lining structure of the T-shaped intersection, so that the construction of the secondary lining will not affect the excavation of the tunnel in front. The secondary lining structure is equipped with a steel arch frame, which can be used as the load-bearing point of the super-large section secondary lining of the connecting road in the direction of the main channel, and can also increase the overall stiffness and stability of the secondary lining of the T-shaped intersection, greatly increasing the construction safety and structural safety. During the construction of the secondary lining structure, it is necessary to pour concrete on the side wall and the rear arch.

[0038] Working principle: by adopting this method, the connection between the construction processes of cross tunnel excavation and primary support, drainage and secondary lining is more reasonable, which speeds up the construction progress and reduces the cost; at the same time, this method can not only ensure the continuous operation of tunnel excavation and primary support in the front, but also ensure the follow-up construction of drainage and secondary lining, so that the advancement of the entire tunnel project will not be greatly affected by the construction of super-large section T-intersection, breaking through the bottleneck of the construction of super-large section T-intersection of the tunnel with great impact on the construction period; such as retaining the super-large section of the connecting road in the middle of the rock, using the left and right guide pits to advance to the main channels on both sides, the construction rhythm of the subsequent processes of the tunnel can be more reasonable; in addition, when constructing the secondary lining structure of the intersection, a portal frame with a T-channel and a full-frame support system are used, so that the construction of the secondary lining will not affect the excavation of the previous tunnel; the technical measures taken by this construction method for the construction of super-large section tunnel T-intersection can effectively improve the construction safety and the overall safety of the secondary lining structure. For example, when the connecting road is converted to the main channel, the middle interlayer of 25m of the connecting road super-large section in the T-shaped intersection between the connecting road and the main channel is retained, and the length of the retained middle interlayer spans the width of the main channel section by about 5m. This effectively suppresses the convergence effect of the surrounding rock disturbance during the excavation process of the connecting road super-large section to the main channel openings on both sides; adding a steel arch frame in the secondary lining can serve as the load-bearing point of the connecting road super-large section secondary lining in the direction of the main channel, and can also increase the overall stiffness and stability of the secondary lining at the T-shaped intersection, greatly increasing the construction safety and structural safety.

[0039] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A safe construction method for a T-shaped intersection in a super-large cross-section tunnel, characterized by: The specific steps include: S1: Double side wall pilot tunnel construction method is used to excavate the left and right side pilot tunnels of the super large section of the connecting road; S2: Excavation of the main channel slope in the pilot pit on the leading side of the connecting road; S3: Excavation of the main channel slope in the guide pit on the rear side of the connecting road; S4: Initial support is carried out on the main channels on both sides, and after the full section of the support is closed, the middle rock of the connecting channel is excavated; S5: Construction of the connecting road invert and arch wall; the specific operation method of the construction is to first carry out initial support for the middle rock invert, and after completion, close the entire section of the initial support of the tunnel into a ring, and determine the stability of the surrounding rock deformation based on the monitoring measurement data, and then gradually remove the temporary supports on both sides of the invert; when the secondary lining structure of the invert is constructed, a steel trestle is set up for passage, and then the portal frame, full-frame support system and combined steel formwork are constructed for the large-section secondary lining arch wall of the connecting road; S6: Use the portal frame and full-frame support system of the T-channel and the combined steel formwork to construct the secondary lining arch wall structure of the T-intersection; The secondary lining structure in S6 is provided with a steel arch frame; The openings of the connecting roads and the main passage in the left and right guide pits are set with joists; The connecting channel is a type IVd tunnel, and the main channel is a type IVb tunnel; The length of the intermediate rock in the connecting road in S4 is 25m; During the construction of the secondary lining structure in S6, concrete pouring needs to be performed on the rear arch of the side wall in turn.

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