Shallow buried section high-speed rail tunnel construction method

Abstract

The invention relates to the technical field of tunnel construction, in particular to a shallow buried section high-speed rail tunnel construction method, which comprises the following steps: S1, surveying and setting out a tunnel construction area, arranging grouting pipes on two sides of a tunnel, and forming grouting areas corresponding to the two sides of the tunnel through grouting; s2, excavation is conducted downwards from the upper portion of the tunnel to the elevation corresponding to a tunnel arch foot, and tunnel construction is conducted through a pouring method; s3, after the tunnel body is maintained to the preset strength, an arch-shaped frame is arranged above the tunnel, and the two ends of the arch-shaped frame are supported on the two sides of a tunnel arch foot; s4, grouting anchor pipes extending in the longitudinal direction are arranged on the arch-shaped frames, and grouting is conducted after backfilling is conducted on the upper portion of the tunnel body; and S5, after grouting is completed, vegetation is planted on the surface of the backfill soil for covering. And backfill soil reinforcement is carried out in cooperation with grouting of the grouting anchor pipe, backfill soil does not need to be compacted through a large machine, the backfill layer forms an overall stable structure after grouting, later-period sedimentation is effectively reduced, and the long-term stability of the tunnel structure is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel construction, and particularly relates to a shallow-buried section high-speed rail tunnel construction method. BACKGROUND

[0002] With the continuous expansion of the high-speed rail transportation network, the proportion of tunnel engineering in high-speed rail construction is gradually increasing. The shallow-buried section tunnel is prone to safety hazards such as collapse and settlement during construction due to thin overburden and poor stability of surrounding rock. The conventional excavation method of the cut-and-cover bench method has problems of complex excavation process and long construction period. The open excavation construction method needs to be backfilled after the tunnel construction is completed, and the backfilling process is prone to the problem of non-dense backfilling. Therefore, a large road roller is needed to compact the backfilling soil during the backfilling process. However, the supporting capacity of the tunnel is limited, and the compaction of the road roller needs to be strictly controlled, otherwise it will lead to uneven stress of the tunnel structure in the later period, affecting the safety and stability of the high-speed rail operation, and the construction risk is large.

[0003] Therefore, it is necessary to provide an improved technical solution for the above-mentioned deficiencies of the prior art. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art. The present application provides a shallow-buried section high-speed rail tunnel construction method.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solution: A shallow-buried section high-speed rail tunnel construction method, comprising the following steps: Step S1, measuring and laying out the tunnel construction area, and setting grouting pipes on both sides of the tunnel, forming grouting areas on both sides of the tunnel by grouting; Step S2, excavating from the top of the tunnel to the corresponding elevation of the tunnel springing, and constructing the tunnel by pouring method; Step S3, after the tunnel main body is maintained to a predetermined strength, an arch-shaped frame is installed above the tunnel, and the two ends of the arch-shaped frame are supported on both sides of the tunnel springing; Step S4, a grouting anchor pipe extending in the longitudinal direction is arranged on the arch-shaped frame, and grouting is performed after backfilling above the tunnel main body; Step S5, after grouting is completed, vegetation is planted on the surface of the backfilling soil for coverage.

[0006] Preferably, in step S1, tube wells are constructed around the excavation area for dewatering. After dewatering to the elevation below the tunnel springing, grouting pipes are constructed. The grouting pipes are distributed in a plum blossom shape and extend in the longitudinal direction to the elevation below the tunnel springing.

[0007] Preferably, in step S2, the excavation is carried out in layers from top to bottom, and the sides are sloped during the excavation process, with a slope angle of 60°. After the excavation is completed, the bottom of the pit is excavated to form an arch bottom, and a layer of plain concrete cushion is poured on the arch bottom.

[0008] Preferably, in step S2, the tunnel construction step comprises: A waterproof layer is laid on the arch bottom, and a steel reinforcement cage corresponding to the arch bottom is laid, and the arch bottom is formed by pouring; After the arch bottom concrete solidifies, steel rails corresponding to the inner and outer formwork trolleys are laid on the upper surface of the arch bottom, the inner formwork trolley is assembled and moved along the steel rails to the construction work site, and an arch-shaped steel reinforcement corresponding to the tunnel shape is laid on the inner formwork trolley; The assembled outer formwork trolley is moved to the construction work site, and end forms corresponding to the ends of the inner and outer formwork trolleys are installed; The concrete is poured from the outer formwork trolley, and after the concrete solidifies, the inner and outer formwork trolleys are demoulded, a waterproof layer is laid on the outer wall of the tunnel, and is sealed and connected with the waterproof layer of the arch bottom; The inner and outer formwork trolleys are poured in sections until the tunnel pouring is completed.

[0009] Preferably, a pouring groove is excavated in the area corresponding to the tunnel arch foot on both sides of the excavation area, the opening of the pouring groove faces the tunnel arch foot, and after the steel reinforcement is bound between the pouring groove and the tunnel arch foot, the concrete is poured to form a concrete platform supporting the arch-shaped frame.

[0010] Preferably, the pouring groove is provided with a lock foot anchor pipe outwardly arranged, and the lock foot anchor pipe is fixedly connected with the internal steel reinforcement.

[0011] Preferably, a plurality of arch-shaped frames are uniformly distributed along the tunnel mileage direction, and a pre-buried bolt corresponding to the arch-shaped frame is arranged on the concrete platform.

[0012] Preferably, the grouting anchor pipe comprises a plurality of segments spliced by threads, and the grouting anchor pipe is lengthened according to the backfilling progress until it extends out of the upper surface of the excavation area.

[0013] Beneficial effect: The backfilling soil is reinforced by grouting with the grouting anchor pipe, and the backfilling soil does not need to be compacted by large machinery. After grouting, the backfilling layer forms a whole stable structure, effectively reducing the later settlement and ensuring the long-term stability of the tunnel structure.

[0014] By grouting and reinforcing on both sides of the tunnel before construction, the influence of underground water on construction is effectively reduced, the compactness and bearing capacity of the surrounding soil are improved, the stability of the pit wall during excavation is ensured, and the risk of collapse is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings accompanying the specification of this application form a part of the disclosure of the application and serve to further provide a further understanding of the application, the illustrative embodiments of the application, and the description of these embodiments serve the purpose of explaining the application and are not intended to limit the application in any way. Among them: Figure 1 This is a schematic diagram of the tunnel structure in a specific embodiment of the present invention.

[0016] 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

[0017] 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.

[0018] 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.

[0019] 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.

[0020] like Figure 1 As 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.

[0021] 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.

[0022] Step S2, the tunnel 1 main body corresponding to the soil excavation is carried out in the form of open excavation, in the process of excavation, in order to ensure the stability of the pit wall, the way of layering from top to bottom is adopted, and the two sides of the excavation are treated by slope, because the grouting pipe 3 can reinforce the soil layer on both sides, so the angle of the slope is controlled to 60°, which can not only ensure the stability of the pit wall, but also reduce the space occupation and improve the construction efficiency.

[0023] After the tunnel 1 is excavated from top to bottom to the elevation corresponding to the arch foot of the tunnel 1, the tunnel 1 is constructed by pouring method.

[0024] Step S3, after the tunnel 1 main body is maintained to the preset strength, the arch-shaped frame 5 is arranged above the tunnel 1, the structure form and material specification of the frame are determined according to the span, height and bearing requirement of the tunnel 1, and the two ends of the arch-shaped frame 5 are supported on both sides of the arch foot of the tunnel 1.

[0025] In order to improve the support stability of the arch-shaped frame 5, the pouring groove 7 is excavated in the area corresponding to the arch foot of the tunnel 1 on both sides of the excavation area, the opening of the pouring groove 7 faces the arch foot of the tunnel 1, and the bottom extends to both sides of the arch foot. Steel bars are bound between the pouring groove 7 and the arch foot of the tunnel 1, the steel bars are reliably connected with the embedded steel bars of the arch foot of the tunnel 1, and then concrete pouring is carried out, forming a concrete platform 6 supporting the arch-shaped frame 5, and the pouring groove 7 excavation provides the engagement ability with the slope surface.

[0026] Step S4, after the installation of the arch-shaped frame 5 is completed, the backfill operation is carried out in the excavation area above the tunnel 1 main body, and the backfill process is carried out in layers, which can be carried out by using small equipment or without backfill soil 2 compaction operation. The arch-shaped frame 5 is provided with a grouting anchor pipe 4 extending in the longitudinal direction, after the backfill operation is completed, the backfill is carried out above the tunnel 1 main body, and then grouting is carried out, the grouting anchor pipe 4 is used to inject grout into the backfill layer, the grout penetrates into the pores of the backfill soil 2, and after solidification, the backfill layer forms a whole stable structure, which further improves the bearing capacity and stability of the backfill area and effectively reduces the later settlement.

[0027] Step S5, after the grouting is completed, vegetation is planted on the surface of the backfill soil 2, which not only beautifies the surrounding environment, but also prevents the loss of backfill soil 2, realizes the ecological restoration of the construction area, and plays a role in water and soil conservation and environment beautification.

[0028] In an optional embodiment, in step S1, the tube well is arranged outside the excavation area to carry out dewatering, so as to avoid the adverse effect of underground water on the construction. The arrangement density and depth of the tube well are determined according to the hydrogeological condition of the construction area, so as to ensure that the dewatering effect can reach below the arch bottom level of the tunnel 1. After the underground water level is stably lowered below the arch bottom level of the tunnel 1, the construction of the grouting pipe 3 is carried out. The grouting pipe 3 is uniformly distributed in the shape of a quincunx, so as to ensure the uniformity of the grouting reinforcement. Meanwhile, the grouting pipe 3 extends to below the arch bottom level of the tunnel 1 along the longitudinal direction, so as to further enhance the reinforcement effect of the surrounding rock at the bottom of the tunnel 1.

[0029] After the dewatering to below the arch bottom level of the tunnel 1, the grouting pipe 3 is constructed. The grouting pipe 3 is distributed in the shape of a quincunx and extends to below the arch bottom level of the tunnel 1 along the longitudinal direction. The spacing of the grouting pipe 3 is 1.5 m, and the diameter is 50-100 mm. The grouting pipe 3 extends to 1-3 m below the arch bottom level of the tunnel 1. The cement-water glass double-liquid slurry is injected into the grouting pipe 3. The grouting pressure is controlled to be 1.5-2.0 MPa, so as to form the grouting reinforcement area on both sides of the tunnel 1.

[0030] In step S2, the excavator is used to excavate from the top of the tunnel 1 to the bottom layer by layer. The thickness of each layer is 2 m. The slope angle on both sides of the excavation is 60°. After the excavation to the arch bottom level of the tunnel 1, the arch bottom excavation is carried out. The arch bottom curvature meets the design requirements. Then, the 10 cm thick C15 plain concrete cushion is poured.

[0031] Further, in step S2, the construction steps of the tunnel 1 include: laying the waterproof layer on the arch bottom. The waterproof layer is SBS modified asphalt waterproof roll material. The hot melt welding is used for sealing at the joint.

[0032] The steel reinforcement cage corresponding to the arch bottom is laid on the plain concrete cushion. The arch bottom is formed by pouring. The steel reinforcement is HRB400 grade, with a diameter of 25 mm and a spacing of 20 cm. After the binding is completed, the C35 concrete is poured to form the arch bottom.

[0033] After the strength of the arch bottom concrete reaches 75%, the steel rail is laid on the upper surface of the arch bottom. The inner mold trolley is assembled and moved to the construction work position. The arch-shaped steel reinforcement corresponding to the shape of the tunnel 1 is laid above the inner mold trolley. The arch-shaped steel reinforcement is welded and connected with the arch bottom steel reinforcement cage. The outer mold trolley is assembled and moved to the construction work position. After the spacing between the inner mold and the outer mold is adjusted, the end mold is installed. The C35 concrete is poured through the pouring opening of the outer mold trolley. The layer-by-layer vibration is carried out by using the plug-in vibrator. After the strength of the concrete reaches 80%, the mold is removed. The SBS modified asphalt waterproof roll material is laid on the outer wall of the tunnel 1 and is welded and sealed with the waterproof layer of the arch bottom.

[0034] The concrete is poured from the outer mold trolley, and after the concrete is solidified, the inner mold trolley and the outer mold trolley are demolded, the waterproof layer is laid on the outer wall of the tunnel 1, and is sealingly connected with the waterproof layer at the arch bottom, so as to form a complete waterproof system of the tunnel 1.

[0035] Due to the long length of the tunnel 1, the inner mold trolley and the outer mold trolley are constructed by using the segmented pouring method, the pouring length of each segment is determined according to the trolley specifications and the construction progress requirements, and the pouring construction of each segment of the tunnel 1 is sequentially completed until the pouring of the entire tunnel 1 main body is completed.

[0036] In an optional embodiment, after the tunnel 1 main body concrete is cured for 28 days or reaches 75% of the design strength, a pouring groove 7 is excavated at the position of the arch foot of the tunnel 1 on both sides of the excavation area, the pouring groove 7 has a depth of 80 cm and a width of 60 cm, and the opening faces the arch foot of the tunnel 1.

[0037] The locking foot anchor pipe 8 is outwardly arranged in the pouring groove 7, and the locking foot anchor pipe 8 is fixedly connected with the steel bars inside. To further enhance the connection strength between the concrete platform 6 and the surrounding rock, the locking foot anchor pipe 8 is outwardly arranged in the pouring groove 7, and the locking foot anchor pipe 8 is fixedly connected with the steel bars inside, so that the locking foot anchor pipe 8, the steel bars and the concrete platform 6 form an integral force structure. A plurality of arch-shaped frames 5 are uniformly distributed along the mileage direction of the tunnel 1, and the spacing is determined according to the design requirements. Pre-buried bolts corresponding to the arch-shaped frames 5 are arranged on the concrete platform 6, the arch-shaped frames 5 are fixedly connected with the concrete platform 6 through the pre-buried bolts, and the installation firmness of the arch-shaped frames 5 is ensured.

[0038] The locking foot anchor pipe 8 has a diameter of 80-90 mm and a depth of 2-5 m, and is weldedly connected with the steel bars in the pouring groove 7. The steel bars between the pouring groove 7 and the arch foot of the tunnel 1 are bound, the steel bars are made of HRB400 grade and have a diameter of 22 mm and a spacing of 15 cm, and then C35 concrete is poured to form the concrete platform 6. Pre-buried bolts are reserved on the concrete platform 6, a plurality of arch-shaped frames 5 (made of H-shaped steel material) are uniformly distributed every 2 m along the mileage direction of the tunnel 1, and are fixedly connected with the concrete platform 6 through the pre-buried bolts.

[0039] In the embodiment, the arch-shaped frame 5 is provided with a grouting anchor pipe 4 extending longitudinally, the grouting anchor pipe 4 is lengthened with the backfilling progress, and is spliced in multiple sections in the form of threads until the grouting anchor pipe 4 extends out of the upper surface of the excavation area. The tunnel 1 body is backfilled with graded sand and gravel, the thickness of each layer is 30 cm, the backfilling soil 2 above the tunnel 1 does not need to be compacted deliberately, and the backfilling soil 2 on both sides of the tunnel 1 can be compacted. The grouting anchor pipe 4 is fixed on the arch-shaped frame 5 by welding, the grouting anchor pipe 4 is gradually lengthened with the backfilling progress until it extends out of the upper surface of the excavation area by 50 cm. After the backfilling is completed, cement slurry is injected into the backfilling layer through the grouting anchor pipe 4, the grouting pressure is controlled at 0.8-1.2 MPa, and it is ensured that the slurry uniformly penetrates into the pores of the backfilling layer.

[0040] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application is within the protection scope of the claims of the present application.

Claims

1. A shallow-buried section high-speed rail tunnel construction method, characterized in that, The method comprises the following steps: Step S1, measuring and laying out the tunnel construction area, and setting grouting pipes on both sides of the tunnel, to form grouting areas on both sides of the tunnel by grouting; Step S2, excavating from the top of the tunnel to the corresponding elevation of the tunnel arch foot, and constructing the tunnel by pouring; Step S3, after the tunnel body is maintained to a preset strength, installing an arch-shaped frame above the tunnel, and supporting the two ends of the arch-shaped frame on both sides of the tunnel arch foot; Step S4, setting a grouting anchor pipe extending in the longitudinal direction on the arch-shaped frame, and grouting after backfilling above the tunnel body; Step S5, planting vegetation on the surface of the backfill soil after grouting is completed.

2. The method according to claim 1, wherein, In step S1, tube wells are constructed around the excavation area to lower the water level, and the grouting pipes are constructed after the water level is lowered to the elevation of the tunnel arch bottom, the grouting pipes are distributed in a plum blossom shape and extend longitudinally to the elevation of the tunnel arch bottom.

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 tunnel is excavated layer by layer from top to bottom, and the sides are sloped during excavation, with a slope angle of 60°; After excavation is completed, the arch bottom is excavated, and a layer of plain concrete cushion is poured on the arch bottom.

4. The method according to claim 3, wherein, In step S2, the tunnel construction steps include: Laying a waterproof layer on the arch bottom, and laying a steel reinforcement cage corresponding to the arch bottom, to form the arch bottom by pouring; After the arch bottom concrete solidifies, laying steel rails corresponding to the inner and outer formwork trolleys on the upper surface of the arch bottom, moving the inner formwork trolley along the steel rails to the construction position, and laying an arch-shaped steel reinforcement corresponding to the tunnel shape on the inner formwork trolley; Moving the assembled outer formwork trolley to the construction position, and installing end forms corresponding to the ends of the inner and outer formwork trolleys; Pouring concrete from the outer formwork trolley, and demolding the inner and outer formwork trolleys after the concrete solidifies, laying a waterproof layer on the outer wall of the tunnel, and sealingly connecting it with the waterproof layer on the arch bottom; The inner and outer formwork trolleys are poured in sections until the tunnel pouring is completed.

5. The method of constructing a shallow depth high-speed rail tunnel according to claim 1, wherein, Excavating a pouring groove on both sides of the excavation area corresponding to the tunnel arch foot, the opening of the pouring groove facing the tunnel arch foot, and pouring concrete after binding the steel bars between the pouring groove and the tunnel arch foot, to form a concrete platform supporting the arch-shaped frame.

6. The shallow-buried section high-speed rail tunnel construction method according to claim 5, characterized in that, The pouring groove is provided with a lock foot anchor pipe that is outwardly set and fixedly connected with the steel bars inside it.

7. The shallow-buried section high-speed rail tunnel construction method according to claim 6, characterized in that, A plurality of arch-shaped frames are uniformly distributed along the tunnel mileage direction, and the concrete platform is provided with pre-buried bolts corresponding to the arch-shaped frames.

8. The method of constructing a shallow depth high-speed rail tunnel according to claim 1, wherein, The grouting anchor pipe comprises multiple segments that are spliced by threads, and the grouting anchor pipe is lengthened according to the backfilling progress until it extends out of the upper surface of the excavation area.

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