Large pipe shed and advanced small pipe combined tunnel supporting system and construction method

Abstract

The invention relates to the field of tunnel supporting, and discloses a large pipe shed and advanced small pipe combined tunnel supporting system and a construction method. The tunnel support system comprises a plug wall; a large pipe shed supporting structure; provided is an advanced small pipe supporting structure. The construction method of the tunnel supporting system comprises the steps that S1, the plug wall is constructed, and the guide pipe is pre-buried; s2, a guide pipe is installed; s3, drilling is conducted, pipe shed steel pipes of the large pipe shed supporting structure are installed, and then grouting reinforcement is conducted; s4, a drilling machine is positioned, and follow-pipe drilling is conducted along the guide pipe; s5, holes are cleaned, and grouting of the pipe shed steel pipes is completed; s6, drilling and reserving a slot position of a guide steel pipe of the advanced small guide pipe supporting structure; s7, a guide steel pipe of the advanced small guide pipe supporting structure is installed, and then grouting reinforcement is conducted; and S8, excavation of a tunnel hole body is carried out. The large pipe shed is combined with the advanced small guide pipe, the bearing capacity of the tunnel arch and the consolidation effect of surrounding rock are remarkably improved, and the influence of construction on the existing viaduct pier is effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of tunnel support, and in particular to a large pipe shed and advanced small guide tube combined type tunnel support system and construction method. Background Art

[0002] In recent years, with the rapid development of urban transportation networks, tunnel projects face severe technical challenges when crossing existing viaduct piers or other structures. During tunnel construction, the distance between the tunnel vault and the existing viaduct pier foundation pit is small, and the vibrations generated by excavation and blasting operations can easily disturb the surrounding rock and soil, causing the existing viaduct piers to sink, become unstable, or even collapse, seriously affecting traffic safety.

[0003] Traditional support methods, such as grouting reinforcement of the rock and soil between the pier foundation pit and the tunnel vault during the tunnel construction phase, will inevitably affect the stability of the elevated bridge piers themselves, cause significant disturbance to the surrounding rock and soil, and may aggravate the settlement and deformation of existing structures. Therefore, traditional support methods are difficult to meet the needs of such complex geological conditions and engineering environments.

[0004] In order to solve the above problems, there is an urgent need for a support system and construction method that can take into account support strength, construction efficiency and safety, so as to ensure the stability and safety of tunnel projects when passing through existing structures. Summary of the invention

[0005] The present application solves the technical problem in the prior art that tunnel projects cause settlement and deformation of structures when passing through existing structures by providing a tunnel support system and construction method combining a large pipe roof and an advanced small guide tube. The application combines the large pipe roof with the advanced small guide tube to form a combined support system, which significantly improves the bearing capacity of the tunnel arch and the consolidation effect of the surrounding rock, and effectively reduces the impact of the construction on the existing elevated bridge piers.

[0006] The present application provides a large pipe shelf and advanced small guide tube combined tunnel support system, including: a plug wall, arranged at the tunnel entrance; a large pipe shelf support structure, which is composed of multiple pipe shelf steel pipes arranged circumferentially along the plug wall, and the pipe shelf steel pipes are provided with a number of shelf pipe grouting holes, and the tails of the pipe shelf steel pipes are provided with stiffening ribs. The pipe shelf steel pipes of the large pipe shelf support structure are constructed by drilling and installing guide pipes pre-buried in the plug wall; the advanced small guide tube support structure, which is composed of multiple guide steel pipes arranged circumferentially along the rock and soil outside the plug wall, and the guide steel pipes are provided with a number of guide tube grouting holes.

[0007] Furthermore, the grouting holes of the pipe-shed steel pipes of the large pipe-shed support structure are arranged in a plum blossom pattern, and the grouting holes of the pipe-shed are arranged circumferentially on the pipe-shed steel pipe and are asymmetrically distributed. Moreover, a grouting hole-free pipe-shed slurry-stop section is reserved at the tail of the pipe-shed steel pipe; a conduit slurry-stop section without grouting holes is reserved at the tail of the guide steel pipe.

[0008] Furthermore, the plug wall is made of shotcrete structure, and a steel mesh is arranged inside. The mesh size of the steel mesh is adapted to the thickness of the shotcrete.

[0009] Furthermore, the arrangement range of the guide pipes covers a preset angular area of the tunnel arch, and each guide pipe maintains an equal set distance from the tunnel excavation contour line.

[0010] This application also provides a construction method for a combined tunnel support system of large pipe-shed and advanced small conduits. The construction method includes the following steps: S1: Construct the plug wall and embed the guide pipes; S2: Install the guide pipes; S3: Drill holes and install the pipe-shed steel pipes of the large pipe-shed support structure, and then carry out grouting reinforcement; S4: Position the drill rig and carry out pipe-following drilling along the guide pipes; S5: Clear the holes and complete the grouting of the pipe-shed steel pipes; S6: Drill holes to reserve the slots for the guide steel pipes of the advanced small conduit support structure; S7: Install the guide steel pipes of the advanced small conduit support structure, and then carry out grouting reinforcement; S8: Carry out the excavation of the tunnel body.

[0011] Furthermore, when installing the large pipe-shed support structure, sectional pipes are used and arranged staggeredly according to odd and even numbers.

[0012] Furthermore, the grouting of the advanced small conduit support structure uses cement slurry or cement slurry-sodium silicate double slurry, and the grouting pressure is dynamically adjusted according to the geological conditions.

[0013] Furthermore, in steps S3 and S7, the grouting parameters are dynamically adjusted according to the on-site test and monitoring data.

[0014] Furthermore, when the pipe-shed steel pipes of the large pipe-shed support structure are drilled, medium and low pressures are used and the drilling is carried out at a constant speed, and the angle of the pipe-shed steel pipes is adjusted in real time through the guiding system.

[0015] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0016] 1. Double support enhances stability: Through the combined support of the large pipe-shed and the advanced small conduits, the bearing capacity of the tunnel arch and the consolidation force of the surrounding rock and soil mass are significantly improved.

[0017] 2. Little construction disturbance: By combining the jacking method and grouting reinforcement, the disturbance to the surrounding rock and soil mass and existing structures is greatly reduced.

[0018] 3. Dynamic adjustment to ensure safety: The grouting parameters and construction process are dynamically adjusted according to on-site test and monitoring data to ensure the support effect and construction safety.

[0019] 4. Wide application range: It is applicable to tunnel projects with complex geological conditions and crossing existing structures, and has high practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional schematic diagram of a combined tunnel support system of large pipe-roof and advanced small pilot pipes in the first embodiment of the present application;

[0021] Figure 2 It is a structural schematic diagram of the pipe-roof steel pipe in the first embodiment of the present application;

[0022] Figure 3 It is a structural schematic diagram of the guide steel pipe in the first embodiment of the present application;

[0023] Figure 4 It is a flow chart of the construction method of a combined tunnel support system of large pipe-roof and advanced small pilot pipes in the second embodiment of the present application;

[0024] In the figure: 100, rock and soil mass; 200, tunnel excavation contour line; 11, plug wall; 12, large pipe-roof support structure; 121, pipe-roof steel pipe; 1211, grouting hole of the pipe; 1212, stiffening rib; 1213, grouting stop section of the pipe; 13, advanced small pilot pipe support structure; 131, guide steel pipe; 1311, grouting hole of the guide pipe; 1312, grouting stop section of the guide pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] To more comprehensively understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with the specification drawings and specific embodiments. The combined tunnel support system of large pipe-roof and advanced small pilot pipes provided by the present application is particularly applicable to tunnel projects under complex geological conditions such as crossing existing elevated bridge piers, and can effectively improve the support strength and construction safety.

[0026] Embodiment 1:

[0027] Refer to Figure 1 , this embodiment provides a combined tunnel support system of large pipe-roof and advanced small pilot pipes, which mainly consists of three parts: a plug wall 11, a large pipe-roof support structure 12, and an advanced small pilot pipe support structure 13. This support system significantly improves the safety and stability of tunnel construction through a double support design.

[0028] The design of the plug wall 11 is as follows:

[0029] Materials and Structure: The plug wall 11 is made of C25 shotcrete with a thickness of 10 cm, and a steel mesh with a diameter of φ8@150×150 mm is arranged inside. This design ensures that the plug wall 11 has sufficient strength and stiffness to effectively support the subsequent construction loads.

[0030] Dimensions and Arrangement: The height of the plug wall 11 is 1 m, and the width covers the part above the transverse center line of the tunnel section. Its function is to serve as the support foundation for the large pipe shed support structure 12, and guide pipes are embedded in the wall to accurately control the drilling direction of the large pipe shed.

[0031] Construction Technology: When constructing the plug wall 11, it is necessary to first carry out measurement and setting out to determine the wall contour; then install the steel mesh to ensure uniform grid spacing; finally, use the wet shotcrete process to spray the concrete in layers to ensure density and flatness. After 24 hours of concrete curing, the construction of the guide pipe can be carried out.

[0032] The design of the large pipe shed support structure 12 is as follows:

[0033] Specifications of the pipe shed steel pipe 121: The pipe shed steel pipe 121 is made of seamless steel pipe with a diameter of φ127 mm and a wall thickness of 8 mm. The single root length is 21 m, and it is processed in sections, with each section length of 3 m. The adjacent sections are connected by screw threads. This sectional design is convenient for transportation and installation, and at the same time improves the bearing capacity of the overall structure.

[0034] Arrangement of grouting holes: The steel pipe is provided with φ10 mm plum blossom-shaped grouting holes with a spacing of 300 mm, and a 1.0 m non-drilled grouting stop section is reserved at the tail. The plum blossom-shaped arrangement ensures uniform diffusion of the slurry and effectively reinforces the surrounding rock.

[0035] Stiffening measures: φ10 stiffening ribs 1212 are welded at the tail of the steel pipe, and the pipe head is processed into a conical shape for easy jacking construction.

[0036] Arrangement method: The circumferential spacing of the pipe shed steel pipe 121 is 300 mm, the external insertion angle is 1°, and it covers a range of 150° of the arch. The joints are arranged staggeredly, and the number of joints in the same section does not exceed 50%, and the adjacent joints are staggered by ≥1 m to reduce the structural weak points.

[0037] The design of the advanced small pipe shed support structure 13 is as follows:

[0038] Specifications of the guide steel pipe 131: The guide steel pipe 131 is made of seamless steel pipe with a diameter of φ42 mm and a wall thickness of 3.5 mm. The standard section length is 3.0 m, and the strengthening section is 2.2 m.

[0039] Arrangement of grouting holes: The guide steel pipe 131 is provided with φ6 - 8 mm grouting holes with a spacing of 200 mm, and a 0.5 m grouting stop section is reserved at the tail.

[0040] Arrangement method: The longitudinal spacing of the guide steel pipes 131 is 1.0 m, the circumferential spacing is 0.3 m, and the outward inclination angle is 15 - 20°. The grouting material for the standard section is cement slurry, and the cement-sodium silicate double-fluid slurry is used in special sections to adapt to different geological conditions.

[0041] A combined tunnel support system of large pipe-roof and advanced small guide pipes provided in the first embodiment adopts double collaborative support. The large pipe-roof provides overall reinforcement, and the advanced small guide pipes enhance local stability. The combination of the two significantly improves the support effect. The drilling accuracy of the pipe-roof is ensured by pre-burying guide pipes, and the grouting parameters are optimized in real time according to the geological monitoring data to ensure the maximization of the reinforcement effect.

[0042] Embodiment 2:

[0043] Refer to Figure 3 , a construction method of a combined tunnel support system of large pipe-roof and advanced small guide pipes, including the following steps:

[0044] S1: Construct the plug wall 11 and pre-bury the guide pipes.

[0045] Among them, S1 includes:

[0046] Surveying and setting out: Accurately calibrate the position of the plug wall 11 and the pre-burial points of the guide pipes to ensure the construction accuracy.

[0047] Installation of steel bar mesh: Bind the steel bar mesh of φ8@150×150 mm and connect it reliably with the initial support structure to enhance the integrity.

[0048] Shotcreting: Adopt the wet shotcreting process to spray C25 concrete in layers to the designed thickness to ensure the density and flatness.

[0049] Curing: Cure the concrete for more than 24 hours. After the strength reaches 70% of the designed strength, carry out the construction of the guide pipes.

[0050] Pre-bury the guide pipes: Pre-bury the φ140 mm guide pipes at the designed angle (outward inclination angle of 1°), and fix them with steel bar supports to ensure that the deviation is controlled within ±1°.

[0051] S2: Install the guide pipes.

[0052] Fix the guide pipes with steel bar supports to prevent displacement during concrete pouring; after the concrete has set, check the angle and position of the guide pipes, and control the deviation within ±1°.

[0053] S3: Drill holes and install the pipe-roof steel pipes 121 of the large pipe-roof support structure 12, and then carry out grouting reinforcement.

[0054] The processing of the pipe-roof steel pipes 121 is carried out in the processing shed by fabricating φ127mm steel pipes, drilling grouting holes 1211 in the shed pipes and welding stiffeners 1212, and segmenting them according to odd and even numbers to avoid the coincidence of adjacent pipe joint positions.

[0055] S4: Position the drilling rig and conduct pipe-following drilling along the guide pipe.

[0056] For the pipe-following drilling of the pipe-roof steel pipes 121, the drilling rig is positioned along the guide pipe, the compressed air pressure is 0.6 - 1.0 MPa, and the drilling is carried out at a uniform speed. The angle is measured every 6 - 10 m of drilling, and the drill tool is adjusted when the deviation exceeds the limit.

[0057] S5: Clear the hole and complete the grouting of the pipe-roof steel pipes 121.

[0058] After clearing the hole with high-pressure air, cement-sodium silicate double-fluid grout is injected, and the pressure is 0.8 - 1.0 MPa.

[0059] S6: Drill the slot positions of the guide steel pipes 131 of the advanced small pipe support structure 13.

[0060] The drilling can be carried out at an external insertion angle of 15 - 20°, and the depth can be 3.0 m.

[0061] S7: Install the guide steel pipes 131 of the advanced small pipe support structure 13, and then carry out grouting reinforcement.

[0062] For the installation of the pipes, φ42mm steel pipes are jacked in, and the orifice is sealed with quick-setting cement.

[0063] For grouting reinforcement, the grouting pressure in the standard section is 0.2 - 0.5 MPa, the diffusion radius is ≥0.25 m, the grouting volume is monitored, and supplementary grouting is carried out at weak parts.

[0064] S8: Carry out the excavation of the tunnel body.

[0065] The CRD method is adopted for step-by-step excavation, and the footage per cycle is 0.5 - 1.0 m. The steel frame is erected in time and sprayed with concrete for sealing.

[0066] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these modifications and variations.

[0067] The above-mentioned are only the preferred specific implementation manners of the embodiments of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application, according to the technical solution and its concept of this application, makes equivalent substitutions or changes, and should be covered by the protection scope of this application.

Claims

1. A large pipe shed and advanced small pipe combined tunnel support system, characterized in that: include: A blocking wall (11) is arranged at the tunnel opening; The large pipe shed support structure (12) is composed of a plurality of pipe shed steel pipes (121) arranged in a circumferential direction along the plug wall (11), the pipe shed steel pipes (121) are provided with a plurality of shed pipe grouting holes (1211), and the tails of the pipe shed steel pipes (121) are provided with stiffening ribs (1212), and the pipe shed steel pipes (121) of the large pipe shed support structure (12) are constructed by drilling and guiding and installing the pipes through guide pipes pre-buried in the plug wall (11); The advanced small conduit support structure (13) is composed of a plurality of guide steel pipes (131) arranged in a circumferential direction along the rock and soil body (100) outside the plug wall (11), and a plurality of conduit grouting holes (1311) are opened on the guide steel pipes (131).

2. A large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 1, characterized in that: The pipe grouting holes (1211) of the pipe grouting steel pipe (121) of the large pipe grouting support structure (12) are arranged in a plum blossom shape, the pipe grouting holes (1211) are arranged in the circumferential direction of the pipe grouting steel pipe (121) and are asymmetrically distributed, and a pipe grouting stop section (1213) without grouting holes is reserved at the tail of the pipe grouting steel pipe (121); and a guide tube grouting stop section (1312) without grouting holes is reserved at the tail of the guide steel pipe (131).

3. A large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 1, characterized in that: The plugging wall (11) adopts a shotcrete structure and is provided with a steel mesh inside, wherein the mesh size of the steel mesh is adapted to the thickness of the shotcrete.

4. A large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 1, characterized in that: The arrangement range of the guide tubes covers a preset angle area of ​​the tunnel arch, and each guide tube maintains an equal set distance from the tunnel excavation contour line (200).

5. A construction method of a large pipe shed and an advanced small pipe combined tunnel support system, characterized in that: Using a large pipe shed and advanced small pipe combined tunnel support system according to any one of claims 1 to 4, the construction method comprises the following steps: S1: constructing a plugging wall (11) and pre-burying a guide pipe; S2: Install the guide tube; S3: drilling and installing the pipe-roof steel pipe (121) of the large pipe-roof support structure (12), followed by grouting reinforcement; S4: Drilling rig positioning, drilling along the guide pipe; S5: cleaning the hole and completing the grouting of the pipe rack steel pipe (121); S6: Drilling a hole to reserve a slot for the guide steel pipe (131) of the advance small guide pipe support structure (13); S7: installing the guide steel pipe (131) of the advanced small guide pipe support structure (13), followed by grouting reinforcement; S8: Excavate the tunnel body.

6. The construction method of a large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 5, characterized in that: The large pipe shed support structure (12) is installed by using segmented piping and arranged in a staggered manner according to odd and even numbers.

7. The construction method of a large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 5, characterized in that: The advanced small-pipe support structure (13) is grouted with cement slurry or cement slurry-water glass double slurry, and the grouting pressure is dynamically adjusted according to geological conditions.

8. The construction method of a large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 5, characterized in that: In step S3 and step S7, the grouting parameters are dynamically adjusted according to the field test and monitoring measurement data.

9. The construction method of a large pipe shed and advanced small pipe combined tunnel support system as claimed in claim 5, characterized in that: When drilling the pipe-roof steel pipe (121) of the large pipe-roof support structure (12), medium-low pressure and uniform speed drilling are adopted, and the angle of the pipe-roof steel pipe (121) is adjusted in real time through a guiding system.

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