Construction technology of shield first tunnel and then well portal ring beam without enclosure structure

Abstract

This invention discloses a construction technology for a shield tunnel portal ring frame beam without retaining structure, comprising the following steps: S1: ground sleeve valve pipe grouting reinforcement, radial grouting inside the shield tunnel; S2: filling the end of the shield tunnel with foamed concrete; S3: during the excavation of the shield tunnel station foundation pit, horizontal steel pipes are installed above, below, left, and right of the shield tunnel for grouting, and inclined steel pipes are installed at the bottom of the shield tunnel for grouting; S4: after the shield tunnel station floor slab is completed, the retaining structure and foamed concrete within the portal area are removed; S5: after cleaning the base surface, the portal ring frame beam is positioned and installed; S6: steel bars and formwork are installed inside the portal ring frame beam, and finally concrete is poured.

Description

Technical Field

[0001] This invention belongs to the field of shield tunnel construction, and specifically relates to a shield tunnel portal frame beam construction technology without retaining structure, which involves tunneling first and then shafting. Background Technology

[0002] Currently, the shield tunneling method is widely used in urban rail transit and urban integrated pipe gallery projects. However, during the construction process, due to reasons such as adjustments to the early planning and design, land acquisition, and traffic diversion, the shield shafts and stations along the tunnel line cannot be constructed in the conventional way. It is necessary to carry out the foundation pit construction of the shield shafts and stations after the shield tunnel construction is completed and the tunnel is formed, that is, tunnel first and shaft later construction.

[0003] In the process of tunnel boring machine (TBM) construction prior to shaft construction, it is necessary to demolish the existing TBM shaft and station retaining structures to construct the portal ring beam. The traditional and common construction method is to excavate part of the soil outside the already formed segments of the TBM tunnel and embed the portal ring beam structure into the outside of the segments for pouring, i.e., to use an externally embedded portal ring beam structure. Since the TBM tunnel construction prior to shaft construction means that the TBM shaft and station retaining structures have already been constructed and need to be demolished later, the externally embedded portal ring beam structure requires excavating part of the soil outside the formed tunnel after the TBM shaft and station retaining structures are demolished to construct the portal ring beam structure. This method is prone to damaging the retaining structures of the TBM shaft and station pit and the sealing and water-stopping effect of the tunnel segments, especially in some complex strata and soft strata, where groundwater outside the TBM shaft and station is prone to seep into the pit and tunnel, creating safety hazards. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a safe and stable construction technology for a shield tunneling tunnel with a portal frame beam without maintenance.

[0005] The technical solution of this invention is to provide a shield tunneling construction technology for a tunnel-first, shaft-later portal frame beam without retaining structure, comprising the following steps:

[0006] S1: Ground sleeve valve pipe grouting reinforcement, radial grouting inside shield tunnel;

[0007] S2: Foamed concrete is used to fill the end of the shield tunnel;

[0008] S3: During the excavation of the shield tunnel station foundation pit, horizontal steel pipes are installed at the top, bottom and left and right sides of the shield tunnel for grouting, and inclined steel pipes are installed at the bottom of the shield tunnel for grouting.

[0009] S4: After the bottom slab of the shield tunnel station is completed, the retaining structure and foamed concrete within the tunnel portal area are removed;

[0010] S5: After cleaning the base surface, position and install the portal frame beam;

[0011] S6: Install steel bars and formwork inside the portal ring beam, and finally pour concrete.

[0012] Furthermore, the portal frame beam is embedded within the shield tunnel.

[0013] Preferably, the sleeve valve tubes in S1 are arranged in a quincunx pattern.

[0014] Preferably, the installation of the portal ring frame beam in S5 uses water-slow-swelling sealant.

[0015] Preferably, the water-swellable sealant is applied to the contact surface between the retaining structure and the portal ring beam, and the water-swellable sealant is also applied to the contact surface between the shield tunnel segments and the portal ring beam.

[0016] Preferably, the shield tunnel segments are equipped with reinforcing bars.

[0017] Preferably, two rebars are installed as a group, arranged along the 360° of the portal frame beam, and embedded in the main steel reinforcement skeleton of the portal frame beam.

[0018] Compared with existing technologies, the advantages of this invention lie in the construction technology of the tunnel-before-shaft portal ring frame beam. By embedding the post-cast portal ring frame beam structure into the formed tunnel segments, it eliminates the need to excavate the soil outside the formed tunnel, and does not damage the formed shield shaft, station retaining structure, or tunnel stability. This solves the dilemma that easily occurs during the construction of the portal ring frame beam when shield tunnels are constructed using the tunnel-before-shaft method, which can damage the shield shaft, station retaining structure, and the water-stopping effect of the formed tunnel, leading to ground leakage, gushing, and structural instability. As an improvement and supplement to the tunnel-before-shaft construction process, this portal ring frame beam construction technology can effectively solve the construction problems of the portal ring frame beam when shield tunnels are constructed using the tunnel-before-shaft method. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the construction steps.

[0020] Figure 2 This is a schematic diagram of ground and foundation pit grouting reinforcement.

[0021] Figure 3 This is a schematic diagram of the construction of the shield tunnel portal ring frame beam;

[0022] Figure 4 yes Figure 3 Construction diagram of the ring frame beam of the tunnel portal in the middle shield tunnel;

[0023] In the diagram: 1. Sleeve valve pipe; 2. Horizontal steel perforated pipe; 3. Segment hoisting hole; 4. Foamed concrete; 5. Inclined steel perforated pipe; 6. Retaining structure; 7. Shield shaft station foundation pit; 8. Shield tunnel; 9. Inner lining wall; 10. Floor slab; 11. Shield tunnel segment; 12. Portal ring frame beam; 13. Shield shaft station; 14. Shield shaft station floor slab; 15. Water-swellable sealant; 16. Rebar installation. Detailed Implementation

[0024] The following is combined with Figure 1-4 The embodiments of the present invention will be described in detail below. The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0025] Example:

[0026] The main construction process of the shield tunneling technology with unsupported structures, involving tunnel construction followed by shaft construction and portal frame beam construction, is as follows:

[0027] S1: Grouting reinforcement of ground sleeve valve pipe 1, radial grouting inside shield tunnel 8;

[0028] S2: The 8th end of the shield tunnel is filled with 4 cubic meters of foamed concrete, and the filling length meets the construction requirements of the retaining structure.

[0029] S3: During the excavation of the shield tunnel station foundation pit 7, horizontal steel pipes 2 are installed above, below, left and right of the shield tunnel 8 in the foundation pit 7 for grouting, and inclined steel pipes 5 are installed at the bottom of the shield tunnel 8 for grouting.

[0030] S4: After the shield tunnel station floor slab 14 is completed, the retaining structure 6 and foamed concrete 4 within the tunnel portal area are removed;

[0031] S5: After cleaning the base surface, position and install the portal ring frame beam 12;

[0032] S6: Install steel bars and formwork inside the portal ring beam 12, and finally pour concrete.

[0033] Preferably, in S1, the ground grouting is carried out by the sleeve valve pipe 1 in a quincunx pattern, and the grouting depth reaches the bottom of the shield tunnel 8;

[0034] Furthermore, steel pipes are installed through the segment hoisting holes 3 inside the shield tunnel 8 for secondary radial grouting reinforcement;

[0035] Preferably, the portal ring beam 12 in S5 is a reinforced concrete structure and is embedded in the shield tunnel 8.

[0036] Preferably, the installation of the portal frame beam 12 in S5 uses water-slow-swelling sealant 15.

[0037] Furthermore, the water-swellable sealant 15 is applied to the contact surface between the retaining structure 6 and the portal ring beam, and the water-swellable sealant 15 is also applied to the contact surface between the shield tunnel segment 11 and the portal ring beam.

[0038] Furthermore, the shield tunnel segment 11 is equipped with rebar 16.

[0039] Preferably, the reinforcing bars 16 are arranged in pairs along the portal ring beam 12 in a 360° pattern and embedded in the main steel reinforcement skeleton of the portal ring beam 12.

[0040] The preferred embodiments of this invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this invention without inventive effort. Therefore, any technical solutions that can be obtained by those skilled in the art based on the concept of this invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A shield tunneling construction technology for a portal frame beam without retaining structure, characterized in that, Includes the following steps: S1: Grouting reinforcement of ground sleeve valve pipe (1), radial grouting inside shield tunnel (8); S2: The end of the shield tunnel (8) is filled with foamed concrete (4); S3: During the excavation of the shield tunnel (7) station foundation pit, horizontal steel pipes (2) are installed above, below and to the left and right of the shield tunnel (8) in the foundation pit (7) for grouting, and inclined steel pipes (5) are installed at the bottom of the shield tunnel (8) for grouting. S4: After the shield tunnel station floor slab (14) is completed, the retaining structure (6) and foamed concrete (4) within the tunnel portal area are removed; S5: After cleaning the base surface, position and install the portal ring frame beam (12); S6: Install steel bars and formwork inside the portal ring beam (12), and finally pour concrete; The portal frame beam (12) is embedded in the shield tunnel (8); The installation of the portal ring frame beam (12) described in S5 uses water-swellable sealant (15); The water-swellable sealant (15) is applied to the contact surface between the retaining structure (6) and the portal ring beam. The water-swellable sealant (15) is also applied to the contact surface between the shield tunnel segment (11) and the portal ring beam.

2. The construction technology of the tunnel portal frame beam without retaining structure for shield tunneling according to claim 1, characterized in that, The shield tunnel segment (11) is equipped with rebar (16).

3. The construction technology of the tunnel portal frame beam without retaining structure for shield tunneling according to claim 2, characterized in that, The two rebars (16) are arranged in a group, along the 360° of the portal ring beam (12), and embedded in the main steel reinforcement skeleton of the portal ring beam (12).

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