A tunnel shallow buried section construction method

Abstract

The application provides a tunnel shallow buried section construction method and relates to the technical field of tunnel construction. Based on the traditional tunneling method, the steel pipe pile implanted in advance is used to replace the intermediate support. The method not only simplifies the repeated support during the traditional tunneling, the support body formed by the more temporary anchor rods and the embedded steel bars and the netting for supporting the top, but also greatly reduces the use of the cement support surface, meets the green construction requirement, improves the construction speed, and simultaneously connects the adjacent primary support steel arch frames and the inverted arches with each other and fixes the steel pipe piles into an integrated body to form a more stable support structure for the tunnel. The method solves the problems of the traditional construction method, such as the complicated operation steps, the complex support mode and the long construction period.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and more specifically, to a method for constructing shallow-buried sections of tunnels. Background Technology

[0002] A tunnel section where the overburden layer is less than twice the tunnel span is considered a shallow-buried section. Tunnels are structures built to traverse mountains when highways or railways encounter obstacles. They generally consist of a main structure and auxiliary structures. The main structure includes the portal and tunnel lining, while the auxiliary structures mainly include tunnel water supply, drainage, ventilation, lighting, and power supply systems. Currently, tunnel excavation primarily employs methods such as single-sidewall pilot tunneling, double-sidewall pilot tunneling, core soil excavation, or cut-and-cover tunneling. However, traditional construction methods involve numerous steps, complex support methods, and long construction periods. Summary of the Invention

[0003] The purpose of this invention is to provide a construction method for shallow buried sections of tunnels, which solves the problems of numerous operation steps, complex support methods, and long construction periods in traditional construction methods.

[0004] The embodiments of the present invention are achieved through the following technical solution: a construction method for shallow buried sections of tunnels, comprising the following steps:

[0005] S1. Measure the geology of the shallow buried section of the tunnel and drive several steel pipe piles downward from the ground of the shallow buried section along the tunnel excavation direction.

[0006] S2. After each steel pipe pile is driven to the predetermined depth, the bearing capacity of the steel pipe pile is measured. If it is not qualified, it is lengthened and driven downward until the predetermined bearing capacity can be met.

[0007] S3. Pour a concrete base into the inner cavity of the steel pipe pile to further reinforce the lower end of the steel pipe pile;

[0008] S4. Using steel pipe piles as the central axis, the tunnel cross-section is divided into left and right sides. The two sides are excavated alternately in a stepped manner in the order of upper left step, upper right step, middle left step, middle right step, lower left step and lower right step.

[0009] S5. After the steel pipe piles are excavated on the upper left step, the corbels are installed near the top of the arch. The corbels are set along the tunnel direction, and the initial support steel arch frames are installed at equal intervals on the upper left step. The initial support steel arch frames are connected to the corbels. The initial support of the upper left step is completed. The upper right step is excavated, and the initial support steel arch frames symmetrical to the left are installed. The initial support of the upper right step is then completed.

[0010] S6. Complete the excavation and preliminary support of the left middle step and the right middle step, but keep the left upper step and the right upper step in a stepped shape with the left middle step and the right middle step.

[0011] S7. When the left and right middle steps have been excavated for about 20m, the left and right lower steps at the bottom of the tunnel design ground are excavated. The lower bracket is installed near the bottom of the arch at the steel pipe pile. Then the invert arch is installed. The invert arch is divided into left and right sections and is symmetrically set about the lower bracket. Then the left and right lower steps are initially supported.

[0012] S8. Cut off the steel pipe pile between the upper and lower corbels and recycle it;

[0013] S9. Install a waterproof layer and drainage ditch, backfill the invert arch, and carry out secondary lining;

[0014] S10. Repeat steps S4-S9 until the shallow buried section of the tunnel is excavated.

[0015] Furthermore, when installing an upper or lower bracket at the next steel pipe pile, it is necessary to connect it with the corresponding upper or lower bracket between it and the previous steel pipe pile.

[0016] Furthermore, during steps S1-S10, construction work can be carried out simultaneously on the shallow buried sections at both ends of the tunnel.

[0017] Furthermore, during steps S1-S3, construction work can be carried out on the tunnel entrance simultaneously, completing the tunnel entrance construction in three steps: side slope excavation, tunnel face support, and intercepting ditch construction.

[0018] Furthermore, the spacing between adjacent steel pipe piles is 3-5m, and the diameter of the steel pipe piles is not less than 600mm.

[0019] Furthermore, when installing the steel arch frame or invert at the steel pipe pile, it is necessary to cut the steel arch frame or invert to an appropriate length so that it can be connected to the steel pipe pile.

[0020] Furthermore, the spacing between adjacent steel arch frames or inverted arches is 50cm.

[0021] Furthermore, during the secondary lining in step S9, the upper corbel, lower corbel, and cut steel pipe piles need to be cast as a whole.

[0022] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0023] Based on traditional tunneling methods, pre-embedded steel pipe piles replace intermediate supports, which not only simplifies the repeated support required in traditional tunneling, which necessitates a large number of temporary anchors and rebar mesh to form a support structure for the top, but also greatly reduces the use of cement support surfaces, meets green construction requirements, and improves construction speed. At the same time, it connects adjacent initial support steel arch frames and invert arches to each other and fixes them into a whole with steel pipe piles, forming a more stable support structure for the tunnel. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This invention provides a schematic diagram of a construction method for shallow buried sections of tunnels.

[0026] Figure 2 This is a schematic diagram showing the completion of step S3 in a method for constructing a shallow tunnel section provided by the present invention.

[0027] Figure 3 A schematic diagram showing the completion of step S6 in a method for constructing a shallow buried section of a tunnel provided by the present invention.

[0028] Figure 4 A schematic diagram showing the completion of step S8 in a method for constructing a shallow buried section of a tunnel provided by the present invention.

[0029] Figure 5 for Figure 4 A schematic diagram of the cross-section after step S7 is completed at point AA;

[0030] Figure 6 for Figure 4 A cross-sectional view of section AA after step S8 is completed;

[0031] Figure 7 for Figure 4 A schematic diagram of the cross-section after step S9 is completed at point AA;

[0032] Icons: 1. Steel pipe pile, 2. Concrete base, 3. Upper left step, 4. Upper right step, 5. Middle left step, 6. Middle right step, 7. Lower left step, 8. Lower right step, 9. Upper corbel, 10. Lower corbel. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] Reference Figures 1 to 7 As shown, this embodiment provides a construction method for shallow buried sections of tunnels, including the following steps:

[0036] S1. Measure the geology of the shallow buried section of the tunnel. Based on the geological conditions, select an appropriate drilling method, usually using a vibratory hammer or rotary drilling rig. Drive several steel pipe piles 1 downward from the ground of the shallow buried section along the tunnel excavation direction. The best effect is achieved when the bottom of the steel pipe piles enters the rock layer.

[0037] S2. After each steel pipe pile 1 is driven to the predetermined depth, the bearing capacity of the steel pipe pile 1 is measured. If it is unqualified, it is continued to be lengthened and driven down by 0.5m-1m. The bearing capacity is then measured again until the steel pipe pile 1 can meet the predetermined bearing capacity.

[0038] S3. Pour concrete base 2 into the inner cavity of steel pipe pile 1 to further reinforce the lower end of steel pipe pile 1 and enhance the stability and bearing capacity of steel pipe pile 1.

[0039] S4. Using steel pipe pile 1 as the central axis, the tunnel section is divided into left and right sides. The two sides are excavated alternately in a stepped manner in the order of upper left step 3, upper right step 4, middle left step 5, middle right step 6, lower left step 7 and lower right step 8. The excavation here is similar to the single-side wall pilot tunnel method, except that the support in the middle is replaced by steel pipe pile 1.

[0040] S5. After the steel pipe pile 1 is excavated in the upper left step 3, the upper bracket 9 is installed near the top of the arch. The upper bracket 9 is set along the tunnel direction, and the initial support steel arch frame is installed at equal intervals in the upper left step 3. The initial support steel arch frame is connected to the upper bracket 9. The initial support of the upper left step 3 is completed. The upper right step 4 is excavated, and the initial support steel frame symmetrical to the left is installed. The initial support of the upper right step 4 is then completed.

[0041] S6. Complete the excavation and preliminary support of the left middle step 5 and the right middle step 6, but keep the left upper step 3 and the right upper step 4 in a stepped shape with the left middle step 5 and the right middle step 6, and excavate and support them alternately to prevent the arch and side walls from collapsing.

[0042] S7. When the left middle step 5 and right middle step 6 have been excavated for about 20m, the left lower step 7 and right lower step 8 at the bottom of the tunnel design ground are excavated. The lower corbel 10 is installed near the bottom of the arch at the steel pipe pile 1, and then the invert arch is installed. The invert arch is divided into left and right sections and is set symmetrically about the lower corbel 10. Then the left lower step 7 and right lower step 8 are initially supported. During the initial support, steel mesh is laid, anchor bolts are driven in and shotcrete is sprayed.

[0043] S8. Cut off the steel pipe pile 1 between the upper corbel 9 and the lower corbel 10 and recycle it; at this time, the initial support steel arch and the invert arch of the same section form a closed loop, which can provide good support for the tunnel top and sidewalls.

[0044] S9. Install a waterproof layer and drainage ditch, backfill the invert arch, and carry out secondary lining.

[0045] S10. Repeat steps S4-S9 until the shallow buried section of the tunnel is excavated.

[0046] like Figure 2-4 As shown, in specific implementation, when installing the upper bracket 9 or lower bracket 10 at the next steel pipe pile 1, it is necessary to connect the corresponding upper bracket 9 or lower bracket 10 between it and the upper steel pipe pile 1, thereby connecting the adjacent initial support steel arch frame and the invert arch to each other and fixing them together with the steel pipe pile 1, thus providing a more stable support for the tunnel.

[0047] More specifically, during steps S1-S10, construction can be carried out simultaneously on the shallow buried sections at both ends of the tunnel. Simultaneous construction at both ends will not affect each other and can also improve construction efficiency.

[0048] Meanwhile, during steps S1-S3, construction work can be carried out at the tunnel entrance simultaneously to improve the construction progress. The tunnel entrance construction is completed in three steps: side slope excavation, tunnel face support, and intercepting ditch construction.

[0049] In specific implementation, for slope excavation: A total station is used for surveying and setting out. Excavators are used to excavate section by section from top to bottom, avoiding bottom excavation or overlapping excavation. Topsoil, shrubs, and loose rocks on the slope above and at the tunnel entrance must be removed. When blasting is required for rocky slope excavation, shallow-hole loosening blasting should be the primary method. Local manual adjustments can also be made. During excavation, the slope and back slope should be checked constantly. If sliding or cracking is observed, the slope should be appropriately reduced. For tunnel face support: After the back slope is trimmed, the slope should be checked with a slope board. Once the slope is deemed acceptable, system anchor bolts should be installed, with the anchor bolt heads exposed. A metal expanded mesh should be hung and welded to the anchor bolt heads to form a whole. Shotcrete should be sprayed immediately after the mesh is installed, and sprayed repeatedly until the designed thickness is achieved. Construction of the intercepting ditch: The intercepting ditch is excavated 5 meters away from the slope. The excavation of the intercepting ditch is mainly carried out by machinery, with manual assistance for finishing. After finishing, 7.5# mortar-grouted rubble masonry is immediately laid and plastered with mortar.

[0050] like Figure 2-4 As shown, the spacing between adjacent steel pipe piles 1 is 3-5m, and the diameter of steel pipe pile 1 is not less than 600mm.

[0051] More specifically, when installing the steel arch frame or invert at the steel pipe pile 1, it is necessary to cut the steel arch frame or invert to an appropriate length to connect it with the steel pipe pile 1, so that they are aligned apex to form a stable top arch. The spacing between adjacent steel arch frames or inverts is 50cm.

[0052] When performing secondary lining in step S9, the upper corbel 9, the lower corbel 10, and the cut steel pipe pile 1 need to be cast together. The top of the steel pipe pile 1 and its ground surface also need to be sealed to prevent debris and rainwater from entering.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 construction method for shallow-buried tunnel sections, characterized in that, Includes the following steps: S1. Measure the geology of the shallow buried section of the tunnel and drive several steel pipe piles downward from the ground of the shallow buried section along the tunnel excavation direction (1). S2. After each steel pipe pile (1) is driven to the predetermined depth, the bearing capacity of the steel pipe pile (1) is measured. If it is not qualified, it is continued to be lengthened and driven downward until the predetermined bearing capacity can be met. S3. Pour concrete base (2) into the inner cavity of steel pipe pile (1) to further reinforce the lower end of steel pipe pile (1); S4. Using the steel pipe pile (1) as the central axis, the tunnel section is divided into left and right sides. The two sides are excavated alternately in the order of upper left step (3), upper right step (4), middle left step (5), middle right step (6), lower left step (7) and lower right step (8). S5. After the steel pipe pile (1) is excavated in the upper left step (3), the upper bracket (9) is installed near the top of the arch of the steel pipe pile (1). The upper bracket (9) is set along the tunnel direction, and the initial support steel arch frame is installed at equal intervals in the upper left step (3). The initial support steel arch frame is connected to the upper bracket (9). The initial support of the upper left step (3) is completed. The upper right step (4) is excavated, and the initial support steel arch frame symmetrical to the left is installed. The initial support at the upper right step (4) is then completed. S6. Complete the excavation and preliminary support of the left middle step (5) and the right middle step (6), but keep the left upper step (3), right upper step (4) and the left middle step (5), right middle step (6) in a stepped shape; S7. When the left middle step (5) and right middle step (6) have been excavated for about 20m, the left lower step (7) and right lower step (8) at the bottom of the tunnel design ground are excavated. The lower corbel (10) is installed near the bottom of the arch on the steel pipe pile (1), and then the invert arch is installed. The invert arch is divided into left and right sections and is symmetrically set about the lower corbel (10). Then the left lower step (7) and right lower step (8) are initially supported. S8. Cut off the steel pipe pile (1) between the upper corbel (9) and the lower corbel (10) and recycle it; S9. Install a waterproof layer and drainage ditch, backfill the invert arch, and carry out secondary lining; S10. Repeat steps S4-S9 until the shallow buried section of the tunnel is excavated. When installing an upper bracket (9) or a lower bracket (10) at the next steel pipe pile (1), it is necessary to connect it with the corresponding upper bracket (9) or lower bracket (10) between it and the previous steel pipe pile (1); During steps S1-S10, construction work can be carried out simultaneously on the shallow buried sections at both ends of the tunnel. When performing steps S1-S3, construction work can be carried out on the tunnel entrance simultaneously. The tunnel entrance construction is completed in three steps: side slope excavation, tunnel face support, and intercepting ditch construction. When installing the steel arch frame or inverted arch located at the steel pipe pile (1), it is necessary to cut the steel arch frame or inverted arch to an appropriate length so that it can be connected to the steel pipe pile (1).

2. The method for constructing a shallow-buried section of a tunnel according to claim 1, characterized in that, The spacing between adjacent steel pipe piles (1) is 3-5m, and the diameter of the steel pipe piles (1) is not less than 600mm.

3. The method for constructing a shallow-buried section of a tunnel according to claim 1, characterized in that, The spacing between adjacent steel arch frames or inverted arches is 50cm.

4. The method for constructing a shallow-buried section of a tunnel according to claim 1, characterized in that, When performing secondary lining in step S9, the upper corbel (9), the lower corbel (10), and the cut steel pipe pile (1) need to be cast together.

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