Pre-supporting excavation supporting structure for silt soil tunnel

Abstract

The utility model discloses a silt type soil tunnel pre-supporting excavation supporting structure in the technical field of underground engineering, which comprises a tunnel outside soil layer section, a tunnel body soil layer section, a tunnel body rock layer section, a rock-soil boundary line and a ground line, and a tunnel entrance slope temporary and permanent supporting structure is arranged at the position of the tunnel outside soil layer section. The tunnel entrance side slope temporary supporting structure comprises a profile steel pile, a steel sheet pile, a profile steel transverse support and a profile steel diagonal brace, the tunnel entrance side slope permanent supporting structure comprises a guide wall, a retaining wall and an open cut tunnel, and a tunnel construction period temporary and permanent supporting structure is arranged at the position of a tunnel body soil layer section. According to the utility model, the profile steel piles and the steel sheet piles are used for pre-supporting the side slope to be excavated at the tunnel portal, the steel sheet propelled section by section is used for pre-supporting the soil layer, after section-by-section excavation, the profile steel arch frame is used for initially supporting the excavated tunnel, and the tunnel body lining is permanently used for supporting; the problems of safety and stability in the construction period and the permanent operation period of tunnel excavation in the soil layer are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of underground engineering, in particular to a pre-support excavation support structure for a silt-sand soil tunnel. Background Art

[0002] With the development of the national economy, the development and utilization of underground space has received more and more attention. The development and utilization of underground space can realize the expansion of urban space, improve the efficiency of land use, stimulate the scientific and technological needs of construction, promote the transformation and technological progress of underground engineering science and technology industry, establish a complete underground disaster prevention space system, and strengthen the country's ability to resist disasters and wars. Tunnels, also known as tunnels, are buildings built underground, underwater or in mountains for laying railways or building roads for motor vehicles to pass.

[0003] The soil of silt, sand or loess has poor stability, fine particles and low cohesion. When constructing tunnel projects in such areas, if the thickness of this soil layer is large, if the soil layer with poor stability at the tunnel entrance is removed by excavation, it will not only result in high slopes and affect the environment, but also cause stability problems for the slopes themselves. At the same time, the particles of silt and loess are fine, and the reinforcement effect of grouting consolidation slurry is poor. Traditional advance reinforcement schemes such as pipe sheds, small guide tubes, and anchor rods cannot effectively reinforce the soil in the tunnel top area to form a load-bearing support arch. Therefore, there are also great technical risks in using traditional advance support followed by soil tunnel excavation. Utility Model Content

[0004] In order to improve the above-mentioned problem that there are great technical risks in excavating earth tunnels after adopting traditional advance support, the utility model provides a pre-support excavation support structure for silt-sand soil tunnels.

[0005] The utility model provides a pre-support excavation support structure for a silt-sand soil tunnel, which adopts the following technical solutions:

[0006] The pre-support excavation support structure of the silt-sand soil tunnel includes a soil layer section outside the tunnel, a soil layer section in the tunnel body, a rock layer section in the tunnel body, a rock-soil boundary line and a ground line. Temporary and permanent support structures for the tunnel entrance slope are arranged at the location of the soil layer section outside the tunnel. The temporary support structure for the tunnel entrance slope includes steel piles, steel sheet piles, steel lateral supports and steel braces. The permanent support structure for the tunnel entrance slope includes a guide wall, a retaining wall and an open tunnel.

[0007] Temporary and permanent support structures for the tunnel construction period are arranged at the location of the soil layer section of the tunnel body. The temporary support structure for the tunnel construction period includes steel pipe piles, steel plates, steel arch frames and mesh sprayed concrete, and the temporary permanent structure for the tunnel construction period includes the tunnel body lining.

[0008] By adopting the above technical scheme, steel piles and steel sheet piles are used to pre-support the slope to be formed by excavation at the tunnel entrance, thereby avoiding the high slope formed by excavation of the soil slope and ensuring safety during construction. Under permanent operation, backfill concrete is set between the outer side of the guide wall and the temporary support structure of the tunnel entrance slope, and backfill soil is set between the open hole and the temporary support structure of the tunnel entrance slope, so as to form a hard structure to provide permanent retaining support for the slope of the tunnel entrance, thereby ensuring permanent operation safety.

[0009] Optionally, the steel piles and steel sheet piles are vertically arranged on both sides of the tunnel entrance slope, and steel lateral supports are provided on the outer sides of the steel piles, and the steel lateral supports are anchored to the steel piles by high-strength bolts.

[0010] By adopting the above technical solution, the slope to be formed by excavation at the tunnel entrance can be temporarily supported, thereby avoiding the high slope formed by excavation of the soil slope and ensuring safety during construction.

[0011] Optionally, a steel brace is provided on the top of the steel pile, the steel brace is arranged on the steel lateral support, and a connecting rod is additionally provided between adjacent steel braces.

[0012] By adopting the above technical solution, the yield resistance of the steel bracing is improved.

[0013] Optionally, a plurality of guide tubes are buried outside the guide wall, the diameter of the guide tubes is slightly larger than the outer diameter of the steel pipe piles, and the arrangement spacing between the guide tubes and the steel pipe piles is 30 cm to 50 cm.

[0014] By adopting the above technical solution, the tunnel entrance slope can be permanently supported.

[0015] Optionally, the steel pipe pile is provided with a flower hole in the rock mass portion, and a plurality of steel bars are placed inside the flower hole, wherein the diameter of the steel bars is 25 mm to 32 mm.

[0016] By adopting the above technical solution, the steel bars and the steel pipe piles are consolidated to form an integral micro pile body.

[0017] Optionally, the length of the steel plate is 1m to 2m, and the steel plate is spliced ​​on the outside of the steel pipe pile.

[0018] By adopting the above technical solution, a soil retaining wall is formed, which solves the problem of poor grouting consolidation effect of fine-grained soil such as silt, sand and loess, and easy soil collapse during chamber excavation.

[0019] Optionally, the bottom of the steel arch frame is configured as a transversely connected closed structure, and pads are provided at the bottom of both sides of the steel arch frame, and the transversely connected part of the bottom of the steel arch frame is cast into the tunnel lining.

[0020] By adopting the above technical solution, the shrinkage deformation or immersion deformation of the steel arch frame after being subjected to force can be reduced.

[0021] Optionally, backfill concrete is provided between the outer side of the guide wall and the temporary supporting structure of the tunnel entrance slope, the open hole is a concrete open hole with an enlarged bottom width, and backfill soil is provided between the open hole and the temporary supporting structure of the tunnel entrance slope.

[0022] By adopting the above technical solution, through the cooperation of backfill concrete and backfill soil, a hard structure is formed to provide permanent retaining support for the slope of the tunnel entrance.

[0023] Optionally, retaining walls are symmetrically arranged on one side of the open hole away from the guide wall, and a road surface is arranged between two groups of retaining walls.

[0024] By adopting the above technical solution, it is convenient to connect internal and external transportation.

[0025] In summary, the present invention has at least one of the following beneficial effects:

[0026] Steel piles and steel sheet piles are used to pre-support the slope to be formed at the tunnel entrance, and steel plates are advanced section by section to pre-support the soil layer. After excavation section by section, steel arch frames are used to provide initial support for the excavated tunnel, and the tunnel lining is used permanently for support, solving the safety and stability issues of tunnel excavation in the soil layer during the construction period and the permanent operation period.

[0027] Steel pipe piles are used to form a supporting skeleton inside and outside the soil to be excavated and the guide walls and arch frames are constructed step by step. Steel plates driven step by step on the outside form a protective wall, which work together to form a soil barrier. This utility model solves the problem of poor grouting consolidation effect of fine-grained soil such as silt, sand and loess, and easy soil collapse during chamber excavation.

[0028] Since silt, sand and loess have fine particles and the bite and cohesion between particles are low, it is relatively easy for the steel plate to be driven directly into the soil layer by external force, thus solving the engineering technical problems of looseness, easy collapse and poor grouting effect caused by fine particles and low bite and cohesion between particles. It is especially suitable for fine-grained soil with low cohesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a vertical longitudinal section view of the support structure of the utility model;

[0031] Figure 2 It is a transverse longitudinal section view of the support structure of the utility model;

[0032] Figure 3 It is a schematic diagram of the soil layer section structure of the tunnel body of the utility model;

[0033] Figure 4 This is a schematic diagram of the guide wall structure of the utility model;

[0034] Figure 5 This is a schematic diagram of the open hole structure of the utility model;

[0035] Figure 6 This is a schematic diagram of the retaining wall structure of the utility model;

[0036] Figure 7 It is a schematic diagram of the temporary support structure of the tunnel entrance slope of the utility model.

[0037] In the figure: 1. Soil layer section outside the tunnel; 2. Soil layer section of the tunnel body; 3. Rock layer section of the tunnel body; 4. Steel piles; 5. Steel sheet piles; 6. Guide wall; 7. Steel pipe piles; 8. Steel plates; 9. Steel arch frame; 10. Hanging mesh sprayed concrete; 11. Tunnel lining; 12. Retaining wall; 13. Open tunnel; 14. Rock-soil boundary line; 15. Backfill concrete; 16. Backfill soil; 17. Steel lateral support; 18. Guide pipe; 19. Ground line; 20. Road surface; 21. Steel brace. DETAILED DESCRIPTION

[0038] The following is combined with Figure 1-7 The utility model is described in further detail.

[0039] Please refer to the attached figure in the instruction manual Figure 1 , Figure 2 , Figure 4 and Figure 7 The utility model provides an embodiment: a pre-support excavation support structure for a silt-sand soil tunnel, comprising an outer soil layer section 1, a tunnel body soil layer section 2, a tunnel body rock layer section 3, a rock-soil boundary line 14 and a ground line 19. A temporary and permanent support structure for the tunnel entrance slope is arranged at the position of the outer soil layer section 1. The temporary support structure for the tunnel entrance slope comprises a steel pile 4, a steel sheet pile 5, a steel lateral support 17 and a steel brace 21. The steel pile 4 and the steel sheet pile 5 are arranged vertically on both sides of the tunnel entrance slope. A steel lateral support 17 is arranged on the outer side of the steel pile 4. The steel lateral support 17 is anchored to the steel pile 4 by high-strength bolts. Thus, the slope to be excavated at the tunnel entrance can be temporarily supported, avoiding the high slope formed by the excavation of the soil slope and ensuring safety during construction.

[0040] Please refer to the attached figure in the instruction manual Figure 4 A steel brace 21 is provided on the top of the steel pile 4, and the steel brace 21 is arranged on the steel transverse support 17, and a connecting rod is added between adjacent steel braces 21 to improve the yield resistance of the steel brace 21.

[0041] Please refer to the attached figure in the instruction manual Figure 2 , Figure 4 , Figure 5 and Figure 6 The permanent support structure of the tunnel entrance slope includes a guide wall 6, a retaining wall 12 and an open hole 13. Backfill concrete 15 is arranged between the outer side of the guide wall 6 and the temporary support structure of the tunnel entrance slope. The open hole 13 is a concrete open hole with an enlarged bottom width. Backfill soil 16 is arranged between the open hole 13 and the temporary support structure of the tunnel entrance slope. Through the cooperation of the backfill concrete 15 and the backfill soil 16, a hard structure is formed to provide permanent retaining support for the tunnel entrance slope.

[0042] Please refer to the attached figure in the instruction manual Figure 2 and Figure 6 A retaining wall 12 is symmetrically arranged on one side of the open hole 13 away from the guide wall 6, and a road surface 20 is arranged between the two sets of retaining walls 12. It is convenient to connect internal and external traffic.

[0043] Please refer to the attached figure in the instruction manual Figure 2 , Figure 3 and Figure 4 The temporary and permanent support structures during the tunnel construction period are arranged at the position of the tunnel body soil layer section 2. The temporary support structure during the tunnel construction period includes steel pipe piles 7, steel plates 8, steel arch frames 9 and mesh sprayed concrete 10. Several guide pipes 18 are buried outside the guide wall 6. The diameter of the guide pipe 18 is slightly larger than the outer diameter of the steel pipe pile 7. The arrangement spacing between the guide pipe 18 and the steel pipe pile 7 is 30cm to 50cm. In this way, the tunnel entrance slope can be permanently supported.

[0044] Please refer to the attached figure in the instruction manual Figure 1 , Figure 2 and Figure 3 The steel pipe pile 7 is provided with a flower hole in the rock mass part, and a number of steel bars are placed inside the flower hole, and the diameter of the steel bars is 25mm to 32mm. The steel bars and the steel pipe pile 7 are consolidated to form an integral micro pile body. The length of the steel plate 8 is 1m to 2m, and the steel plate 8 is spliced ​​on the outside of the steel pipe pile 7. The soil protection is formed, which solves the problem that the grouting consolidation effect of fine-grained soil such as silt, sand and loess is poor, and the soil collapse is easy to occur during the excavation of the chamber.

[0045] Please refer to the attached figure in the instruction manual Figure 2 and Figure 3The temporary permanent structure during the tunnel construction period includes the tunnel lining 11, the bottom of the steel arch frame 9 is set as a closed structure with transverse connection, and pads are set at the bottom of both sides of the steel arch frame 9, and the transverse connection part of the bottom of the steel arch frame 9 is cast into the tunnel lining 11. This reduces the shrinkage deformation or immersion deformation of the steel arch frame 9 after being stressed.

[0046] Working principle: On the U-shaped sideline to be excavated outside the tunnel entrance, steel piles 4 and steel sheet piles 5 are driven. The steel piles 4 and steel sheet piles 5 are arranged vertically to facilitate the pre-support of the slope to be formed by the tunnel entrance, ensuring the safety during construction. The depth below the excavation ground line 19 is not less than 1 / 2 of the upper part, that is, the length buried in the soil is 1 / 3 of the total pile length, and the soil trenching outside the tunnel is carried out to expose the tunnel face slope;

[0047] During the excavation process, steel reinforcement is carried out in time according to the excavation depth. A steel transverse support 17 is set on the outside of the steel pile 4. The steel transverse support 17 is anchored with the steel pile 4 by high-strength bolts. At the position where the retaining height exceeds 3m, a steel support 21 is set on the top of the steel pile 4 on both sides of the tunnel entrance. The steel support 21 is arranged on the steel transverse support 17. Connecting rods are added between adjacent steel supports 21. The tunnel entrance guide wall 6 is cast. The guide pipe 18 is buried and arranged close to the outer wall of the guide wall 6, and the backfill concrete 15 and the backfill soil 16 are used together to facilitate the permanent support of the slope to be excavated at the tunnel entrance;

[0048] During the construction process, if the guide wall 6 is affected by the steel brace 21, the steel brace 21 is directly cast in the concrete of the guide wall 6. When the concrete in the guide wall 6 reaches the design strength, the steel brace 21 in the hole of the guide wall 6 is cut and removed, and holes are drilled along the guide pipe 18 of the guide wall 6, and the steel pipe pile 7 and the steel bar bundle are inserted and grouting is performed. When the soil is difficult to form a hole due to hole collapse and other reasons, the follow-up pipe drilling is adopted, and the follow-up pipes are fixed by threaded joints, and the follow-up pipes are directly used as the pipe body of the steel pipe pile 7;

[0049] When the mortar of the steel pipe pile 7 reaches the designed strength, a steel plate 8 is driven into the outer side of the pile close to the pipe wall. The front edge of the first steel plate 8 is cut to form a cutting edge to reduce the resistance of the steel plate 8. The number of sections of the first driven steel plate 8 is determined according to the self-stabilizing ability of the tunnel face. Multiple sections of the steel plate 8 can be driven in. The tunnel body is excavated under the protection of the first steel plate 8. The excavation adopts a non-explosive method, and the excavation depth is controlled at about 50 cm, or the range supported by a steel arch frame 9, and it is ensured that the unexcavated part of the steel plate 8 is sufficient to support the stability of the tunnel face or the range of the tunnel face collapse does not exceed the end of the steel plate 8.

[0050] After excavating for a period of time, the steel arch frame 9 and the mesh sprayed concrete 10 are constructed in the tunnel body, and the steel plate 8 is driven in from outside the tunnel again. The steel plate 8 previously driven in the soil body is further pushed deeper into the soil body, and the tunnel body excavation and support are repeated until the excavation and support of the entire chamber in the soil layer are completed, and permanent support construction is carried out.

[0051] The above are all preferred embodiments of the present utility model, and are not intended to limit the protection scope of the present utility model. Therefore, any equivalent changes made based on the structure, shape, and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. A pre-support excavation support structure for a silt-sand soil tunnel, comprising a soil layer section outside the tunnel (1), a soil layer section in the tunnel body (2), a rock layer section in the tunnel body (3), a rock-soil boundary line (14) and a ground line (19), characterized in that: Temporary and permanent support structures for the tunnel entrance slope are arranged at the location of the soil layer section (1) outside the tunnel, the temporary support structure for the tunnel entrance slope comprises steel piles (4), steel sheet piles (5), steel lateral supports (17) and steel cross supports (21), and the permanent support structure for the tunnel entrance slope comprises a guide wall (6), a retaining wall (12) and an open tunnel (13); Temporary and permanent support structures for the tunnel construction period are arranged at the location of the tunnel body soil layer section (2); the temporary support structure for the tunnel construction period comprises steel pipe piles (7), steel plates (8), steel arch frames (9) and mesh sprayed concrete (10); and the permanent support structure for the tunnel construction period comprises a tunnel body lining (11).

2. The silt-sand soil tunnel pre-support excavation support structure according to claim 1 is characterized by: The steel piles (4) and the steel sheet piles (5) are arranged vertically on both sides of the tunnel entrance slope, and steel lateral supports (17) are provided outside the steel piles (4). The steel lateral supports (17) are anchored to the steel piles (4) by high-strength bolts.

3. The silt-sand soil tunnel pre-support excavation support structure according to claim 1 is characterized in that: A steel brace (21) is provided on the top of the steel pile (4), the steel brace (21) is arranged on the steel transverse support (17), and connecting rods are provided between adjacent steel braces (21).

4. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: A plurality of guide tubes (18) are buried outside the guide wall (6); the diameter of the guide tube (18) is greater than the outer diameter of the steel pipe pile (7); and the spacing between the guide tube (18) and the steel pipe pile (7) is 30 cm to 50 cm.

5. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: The steel pipe pile (7) is provided with a flower hole in the rock mass portion, and a plurality of steel bars are placed inside the flower hole, wherein the diameter of the steel bars is 25 mm to 32 mm.

6. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: The length of the steel plate (8) is 1 m to 2 m, and the steel plate (8) is spliced ​​on the outside of the steel pipe pile (7).

7. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: The bottom of the steel arch frame (9) is configured as a transversely connected closed structure, and pads are provided at the bottom of both sides of the steel arch frame (9), and the transversely connected portion of the bottom of the steel arch frame (9) is cast into the tunnel lining (11).

8. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: Backfill concrete (15) is provided between the outer side of the guide wall (6) and the temporary support structure of the tunnel entrance slope, the open hole (13) is a concrete open hole with an enlarged bottom width, and backfill soil (16) is provided between the open hole (13) and the temporary support structure of the tunnel entrance slope.

9. The silt-sand soil tunnel pre-support excavation support structure according to claim 1, characterized in that: A retaining wall (12) is symmetrically arranged on one side of the open hole (13) facing away from the guide wall (6), and a road surface (20) is arranged between two groups of retaining walls (12).

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