A shallow-buried section high-speed rail tunnel construction method
By reinforcing the surrounding rock with grouting on both sides of the tunnel, and combining the construction methods of arched frames and grouting anchor pipes, the problems of collapse and settlement in the construction of shallow-buried high-speed railway tunnels were solved, and the stability and safety of the tunnel structure were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA RAILWAY NO 9 GROUP CO LTD
- Filing Date
- 2026-03-16
- Publication Date
- 2026-06-16
AI Technical Summary
Shallow-buried sections of high-speed railway tunnels are prone to safety hazards such as collapse and settlement during construction. Conventional underground excavation bench method has complex procedures and long construction period, while open excavation method has poor backfilling, which can easily affect the stability and safety of the tunnel structure.
Grouting was carried out by installing grouting pipes on both sides of the tunnel to reinforce the surrounding rock. The tunnel was excavated in layers from top to bottom using the open-cut method. An arch frame was installed and grouting anchor pipes were used for reinforcement during the backfilling process. Finally, vegetation was planted to cover the tunnel.
It improves the density and bearing capacity of the soil around the tunnel, reduces the risk of collapse, ensures the long-term stability and safety of the tunnel structure, and reduces the construction period and the problem of insufficient backfilling.
Smart Images
Figure CN121827381B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of tunnel construction, specifically relating to a construction method for shallow-buried high-speed railway tunnels. Background Technology
[0002] With the continuous expansion of the high-speed rail network, tunnel engineering accounts for an increasing proportion of high-speed rail construction. Among them, shallow-buried tunnels are prone to safety hazards such as collapse and settlement during construction due to their thin overburden and poor surrounding rock stability. Conventional mined excavation methods have problems such as complex excavation procedures and long construction periods. Open-cut construction methods require backfilling after tunnel construction, and the backfill is prone to being incompletely compacted. Therefore, large road rollers are needed to compact the backfill soil during the backfilling process. However, the tunnel's support capacity is limited, and the compaction time of the road rollers needs to be strictly controlled. Otherwise, it will lead to uneven stress on the tunnel structure in the later stage, affecting the safety and stability of high-speed rail operation, and the construction risk is relatively high.
[0003] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a method for constructing shallow-buried high-speed railway tunnels.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A construction method for shallow-buried high-speed railway tunnels includes the following steps:
[0007] Step S1: Measure and set out the tunnel construction area, and install grouting pipes on both sides of the tunnel to form grouting areas on both sides of the tunnel through grouting.
[0008] Step S2: Excavate downwards from above the tunnel to the elevation corresponding to the tunnel arch foot, and construct the tunnel using the pouring method.
[0009] Step S3: After the main tunnel body has been cured to the preset strength, an arched frame is installed above the tunnel, with both ends of the arched frame supported on both sides of the tunnel arch foot.
[0010] Step S4: Grouting anchor pipes extending longitudinally are installed on the arch frame, and grouting is carried out after backfilling above the tunnel body;
[0011] Step S5: After grouting is completed, plant vegetation on the surface of the backfill soil to cover it.
[0012] Preferably, in step S1, a manhole is constructed around the excavation area to dewater the area. After the water level drops below the tunnel arch bottom elevation, grouting pipes are constructed. The grouting pipes are distributed in a quincunx pattern and extend longitudinally to below the tunnel arch bottom elevation.
[0013] Preferably, in step S2, the excavation is carried out in layers from top to bottom, and the slopes on both sides are laid during the excavation process, with a slope angle of 60°.
[0014] After the excavation is completed, the bottom of the pit is excavated to form an arch, and a layer of plain concrete is poured at the bottom of the arch.
[0015] Preferably, in step S2, the tunnel construction steps include:
[0016] A waterproof layer is laid at the bottom of the arch, and a corresponding steel cage is laid at the bottom of the arch. The bottom of the arch is then formed by pouring concrete.
[0017] After the concrete at the bottom of the arch has solidified, steel rails corresponding to the inner and outer formwork trolleys are laid on the upper surface of the bottom of the arch. After the inner formwork trolley is assembled, it moves along the steel rails to the construction position. Arch-shaped steel bars corresponding to the shape of the tunnel are laid on top of the inner formwork trolley.
[0018] Move the assembled outer mold trolley to the construction site and install the end molds at the ends of the corresponding inner mold trolley and outer mold trolley.
[0019] Concrete is poured from the outer formwork trolley. After the concrete has set, the inner and outer formwork trolleys are demolded. A waterproof layer is laid on the outer wall of the tunnel and sealed to the waterproof layer at the bottom of the arch.
[0020] The inner mold trolley and the outer mold trolley are poured in sections until the tunnel pouring is completed.
[0021] Preferably, a pouring trench is excavated on both sides of the excavation area corresponding to the tunnel arch foot, with the opening of the pouring trench facing the tunnel arch foot. After reinforcing bars are tied between the pouring trench and the tunnel arch foot, concrete is poured to form a concrete platform supporting the arch frame.
[0022] Preferably, the casting trench is provided with outwardly driven anchor pipes, which are fixedly connected to the internal reinforcing bars.
[0023] Preferably, the multiple arched frames are evenly distributed along the tunnel mileage direction, and the concrete platform is provided with pre-embedded bolts corresponding to the arched frames.
[0024] Preferably, the grouting anchor pipe comprises multiple sections spliced together by threads, and the grouting anchor pipe extends to the backfill progress until it extends beyond the upper surface of the excavation area.
[0025] Beneficial effects: When used in conjunction with grouting anchor pipes for backfill reinforcement, the backfill soil does not require compaction with large machinery. After grouting, the backfill layer forms an integral and stable structure, effectively reducing subsequent settlement and ensuring the long-term stability of the tunnel structure.
[0026] By grouting and reinforcing both sides of the tunnel before construction, the impact of groundwater on construction was effectively reduced, the density and bearing capacity of the surrounding soil were improved, the stability of the pit wall was ensured during excavation, and the risk of collapse was reduced. Attached Figure Description
[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:
[0028] Figure 1 This is a schematic diagram of the tunnel structure in a specific embodiment of the present invention.
[0029] In the diagram: 1. Tunnel; 2. Backfill soil; 3. Grouting pipe; 4. Grouting anchor pipe; 5. Arch frame; 6. Concrete platform; 7. Pouring trench; 8. Anchor pipe. Detailed Implementation
[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.
[0031] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.
[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.
[0033] like Figure 1As shown, a construction method for a shallow-buried high-speed railway tunnel includes the following steps: Step S1, measuring and setting out the construction area of tunnel 1 to accurately determine the excavation outline of tunnel 1, the location of grouting pipe 3, and the baseline of each subsequent construction procedure. Grouting pipe 3 is installed on both sides of tunnel 1, and grout is injected into the grouting pipe 3 through grouting equipment to form grouting areas on both sides of tunnel 1, so as to improve the density and bearing capacity of the surrounding rock of tunnel 1 and provide stable soil conditions for subsequent excavation construction.
[0034] Furthermore, the slope of the excavation can be increased during the excavation process, saving the space required for construction and reducing the amount of construction work.
[0035] Step S2: The soil corresponding to the main body of Tunnel 1 is excavated in the form of open excavation. In order to ensure the stability of the pit wall during the excavation process, the excavation is carried out in layers from top to bottom. At the same time, the slope is treated on both sides of the excavation. Since the grouting pipe 3 can reinforce the soil layers on both sides, the slope angle is controlled at 60°. This angle can not only ensure the stability of the pit wall, but also reduce the space occupation and improve the construction efficiency.
[0036] After excavating downwards from above Tunnel 1 to the elevation corresponding to the arch foot of Tunnel 1, Tunnel 1 was constructed using the pouring method.
[0037] Step S3: After the main body of tunnel 1 has been cured to the preset strength, an arch frame 5 is installed above tunnel 1. The structural form and material specifications of the arch frame are determined according to the span, height and load-bearing requirements of tunnel 1. The two ends of the arch frame 5 are supported on both sides of the arch foot of tunnel 1.
[0038] To improve the support stability of the arch frame 5, pouring trenches 7 are excavated on both sides of the excavation area corresponding to the arch foot of tunnel 1. The opening of the pouring trenches 7 faces the arch foot of tunnel 1, and the bottom extends to both sides of the arch foot. Reinforcing bars are tied between the pouring trenches 7 and the arch foot of tunnel 1, and the reinforcing bars are reliably connected to the pre-embedded reinforcing bars of the arch foot of tunnel 1. Concrete is then poured to form a concrete platform 6 supporting the arch frame 5, which provides interlocking ability with the slope through the excavation of the pouring trenches 7.
[0039] Step S4: After the arch frame 5 is installed, backfilling is carried out in the excavated area above the main body of tunnel 1. During the backfilling process, the backfill is spread in layers. Small equipment can be used or the backfill soil 2 can be compacted without compaction. The arch frame 5 is equipped with grouting anchor pipes 4 extending longitudinally. After the backfilling is completed, grouting is carried out after backfilling above the main body of tunnel 1. Grout is injected into the backfill layer through the grouting anchor pipes 4. The grout penetrates into the pores of the backfill soil 2. After solidification, the backfill layer forms an integral and stable structure, which further improves the bearing capacity and stability of the backfill area and effectively reduces the later settlement.
[0040] Step S5: After grouting is completed, vegetation is planted and covered on the surface of backfill soil 2. The vegetation cover not only beautifies the surrounding environment, but also helps to conserve water and soil and prevent the loss of backfill soil 2, thus realizing the ecological restoration of the construction area and playing a role in conserving water and soil and beautifying the environment.
[0041] In an optional embodiment, in step S1, manholes are installed around the excavation area for dewatering. To avoid adverse effects of groundwater on construction, manholes are installed around the excavation area for dewatering. The density and depth of the manholes are determined based on the hydrogeological conditions of the construction area to ensure that the dewatering effect reaches below the arch bottom elevation of Tunnel 1. After the groundwater level stabilizes and drops below the arch bottom elevation of Tunnel 1, the grouting pipes 3 are installed. The grouting pipes 3 are evenly distributed in a quincunx pattern to ensure the uniformity of grouting reinforcement. At the same time, the grouting pipes 3 extend longitudinally below the arch bottom elevation of Tunnel 1 to further enhance the reinforcement effect of the surrounding rock at the bottom of Tunnel 1.
[0042] After the water level drops below the arch bottom elevation of Tunnel 1, the grouting pipes 3 are constructed. The grouting pipes 3 are distributed in a quincunx pattern and extend longitudinally to below the arch bottom elevation of Tunnel 1. The spacing of the grouting pipes 3 is 1.5m, the diameter is 50-100mm, and they extend 1-3m below the arch bottom elevation of Tunnel 1. Cement-water glass double liquid grout is injected into the grouting pipes 3, and the grouting pressure is controlled at 1.5-2.0MPa to form grouting reinforcement areas on both sides of Tunnel 1.
[0043] In step S2, an excavator is used to excavate in layers from above Tunnel 1 downwards, with each layer being 2m thick and the slope angle on both sides of the excavation being 60°. After excavating to the arch bottom elevation of Tunnel 1, the arch bottom is excavated, and the arch bottom curvature meets the design requirements. Subsequently, a 10cm thick C15 plain concrete cushion layer is poured. The thickness of the plain concrete cushion layer is determined according to the design requirements. Its function is to provide temporary support and leveling for the arch bottom, providing a flat and solid working surface for the subsequent laying of the waterproof layer and reinforcement binding of the arch bottom.
[0044] Furthermore, in step S2, the construction steps of tunnel 1 include: laying a waterproof layer at the bottom of the arch, the waterproof layer being an SBS modified bitumen waterproof membrane, and sealing the joints with hot-melt welding.
[0045] A steel cage corresponding to the arch bottom is laid on the plain concrete cushion layer, and the arch bottom is formed by pouring concrete. The steel bars are HRB400 grade, with a diameter of 25mm and a spacing of 20cm. After the binding is completed, C35 concrete is poured to form the arch bottom.
[0046] After the concrete at the arch base reaches 75% strength, steel rails are laid on the upper surface of the arch base. The inner formwork trolley is assembled and moved to the construction position. Arch-shaped reinforcing bars corresponding to the shape of Tunnel 1 are laid above the inner formwork trolley and welded to the arch base reinforcing cage. The outer formwork trolley is assembled and moved to the construction position. After adjusting the spacing between the inner and outer formwork, the end formwork is installed. C35 concrete is poured through the pouring port of the outer formwork trolley and vibrated in layers using an immersion vibrator. The formwork is removed after the concrete strength reaches 80%. SBS modified bitumen waterproof membrane is laid on the outer wall of Tunnel 1 and welded to the arch base waterproof layer for sealing.
[0047] Concrete is poured from the outer formwork trolley. After the concrete has set, the inner and outer formwork trolleys are demolded. A waterproof layer is laid on the outer wall of Tunnel 1 and sealed to the waterproof layer at the bottom of the arch, forming a complete waterproof system for Tunnel 1.
[0048] Due to the long length of Tunnel 1, the inner and outer formwork trolleys were constructed using a segmented pouring method. The length of each segment was determined according to the trolley specifications and construction schedule requirements. The pouring of each segment of Tunnel 1 was completed sequentially until the main body of Tunnel 1 was fully poured.
[0049] In one optional embodiment, after the main concrete of tunnel 1 has been cured for 28 days or has reached 75% of its design strength, a pouring trench 7 is excavated on both sides of the excavation area corresponding to the arch foot of tunnel 1. The pouring trench 7 has a depth of 80cm, a width of 60cm, and an opening facing the arch foot of tunnel 1.
[0050] Anchor pipes 8 are driven outwards within the pouring trench 7 and are fixedly connected to the internal reinforcing bars. To further enhance the connection strength between the concrete platform 6 and the surrounding rock, anchor pipes 8 are driven outwards within the pouring trench 7 and are fixedly connected to the internal reinforcing bars, forming an integral load-bearing structure with the anchor pipes 8, reinforcing bars, and concrete platform 6. Multiple arched frames 5 are evenly distributed along the tunnel 1 mileage direction, with spacing determined according to design requirements. Pre-embedded bolts corresponding to the arched frames 5 are installed on the concrete platform 6, and the arched frames 5 are fixedly connected to the concrete platform 6 through the pre-embedded bolts to ensure the installation firmness of the arched frames 5.
[0051] The anchor pipe 8 has a diameter of 80-90mm and a depth of 2-5m, and is welded to the reinforcing bars in the casting trench 7. The reinforcing bars between the casting trench 7 and the arch foot of tunnel 1 are tied together. The reinforcing bars are HRB400 grade, 22mm in diameter, and spaced 15cm apart. C35 concrete is then poured to form the concrete platform 6. Embedded bolts are pre-installed on the concrete platform 6. Multiple arch-shaped frames 5 (made of H-beams) are evenly distributed every 2m along the tunnel 1 mileage direction and are fixedly connected to the concrete platform 6 using these pre-embedded bolts.
[0052] In this embodiment, a longitudinally extending grouting anchor pipe 4 is installed on the arch frame 5. The grouting anchor pipe 4 is lengthened as the backfilling progresses, and multiple sections are spliced together using a threaded method until the grouting anchor pipe 4 extends beyond the upper surface of the excavation area. Graded sand and gravel are used to backfill the area above the main body of tunnel 1, with a layer thickness of 30cm. No special compaction of the backfill soil 2 is required in the area directly above tunnel 1, but the backfill soil 2 on both sides of tunnel 1 can be compacted. The grouting anchor pipe 4 is fixed to the arch frame 5 by welding. The grouting anchor pipe 4 is gradually lengthened as the backfilling progresses until it extends 50cm beyond the upper surface of the excavation area. After backfilling is completed, cement grout is injected into the backfill layer through the grouting anchor pipe 4. The grouting pressure is controlled at 0.8-1.2MPa to ensure that the grout penetrates evenly into the pores of the backfill layer.
[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.
Claims
1. A shallow-buried section high-speed rail tunnel construction method, characterized in that, Includes the following steps: Step S1: Measure and set out the tunnel construction area, and install grouting pipes on both sides of the tunnel to form grouting areas on both sides of the tunnel through grouting. Step S2: Excavate downwards from above the tunnel to the elevation corresponding to the tunnel arch foot, and construct the tunnel using the pouring method. Step S3: After the main tunnel body has been cured to the preset strength, an arched frame is installed above the tunnel, with both ends of the arched frame supported on both sides of the tunnel arch foot. Step S4: Grouting anchor pipes extending longitudinally are installed on the arch frame, and grouting is carried out after backfilling above the tunnel body; Step S5: After grouting is completed, plant vegetation on the surface of the backfill soil to cover it. In step S2, the tunnel construction steps include: A waterproof layer is laid at the bottom of the arch, and a corresponding steel cage is laid at the bottom of the arch. The bottom of the arch is then formed by pouring concrete. After the concrete at the bottom of the arch has solidified, steel rails corresponding to the inner and outer formwork trolleys are laid on the upper surface of the bottom of the arch. After the inner formwork trolley is assembled, it moves along the steel rails to the construction position. Arch-shaped steel bars corresponding to the shape of the tunnel are laid on top of the inner formwork trolley. Move the assembled outer mold trolley to the construction site and install the end molds at the ends of the corresponding inner mold trolley and outer mold trolley. Concrete is poured from the outer formwork trolley. After the concrete has solidified, the inner and outer formwork trolleys are demolded. A waterproof layer is laid on the outer wall of the tunnel and sealed to the waterproof layer at the bottom of the arch. The inner mold trolley and the outer mold trolley are poured in sections until the tunnel pouring is completed.
2. The method of claim 1, wherein the shallow depth section of the high-speed rail tunnel is constructed by using a tunneling machine. In step S1, manholes are constructed around the excavation area to dewater the area. After the water level drops below the tunnel arch bottom elevation, grouting pipes are constructed. The grouting pipes are distributed in a quincunx pattern and extend longitudinally to below the tunnel arch bottom elevation.
3. The method of claim 1, wherein the shallow depth section of the high-speed rail tunnel is constructed by using a tunneling machine. In step S2, the excavation is carried out in layers from top to bottom, and the slopes on both sides are sloped at an angle of 60° during the excavation process. After the excavation is completed, the bottom of the pit is excavated to form an arch, and a layer of plain concrete is poured at the bottom of the arch.
4. The method of constructing a shallow depth high-speed rail tunnel according to claim 1, wherein, In the area corresponding to the tunnel arch foot on both sides of the excavation area, pouring trenches are excavated with the openings of the pouring trenches facing the tunnel arch foot. After tying steel bars between the pouring trenches and the tunnel arch foot, concrete is poured to form a concrete platform that supports the arch frame.
5. The shallow-buried section high-speed rail tunnel construction method according to claim 4, characterized in that, The casting trench is equipped with outward-facing anchor pipes, which are fixedly connected to the internal reinforcing bars.
6. The shallow-buried section high-speed rail tunnel construction method according to claim 5, characterized in that, Multiple arched frames are evenly distributed along the tunnel mileage direction, and pre-embedded bolts corresponding to the arched frames are provided on the concrete platform.
7. The method of constructing a shallow depth high-speed rail tunnel according to claim 1, wherein, Grouting anchor pipes consist of multiple sections spliced together by threads. The grouting anchor pipes are extended to advance the backfilling process until they extend beyond the upper surface of the excavated area.