A construction method for shallow-buried tunnel arches

Abstract

The application discloses a shallow-buried tunnel arch upper open and arch lower excavation construction method and relates to the technical field of tunnel construction. The method comprises the following steps: S1, leveling a roof gutter and excavating a side slope; S2, excavating an arch part by an open excavation method; S3, constructing an arch part support; S4, backfilling an upper arch; S5, excavating by three steps and a temporary inverted arch; S6, secondary lining; and S7, laying a waterproof layer. The shallow-buried tunnel arch upper open and arch lower excavation construction method effectively controls surface subsidence in shallow-buried underpass tunnel construction, protects ground buildings, avoids the influence of tunnel construction on the ground buildings, avoids the result of demolishing the ground buildings, greatly saves construction time, thereby saving cost, the secondary lining structure of the tunnel is rationally designed, the construction method is simple, and the construction quality is easy to control, so that construction cost can be greatly reduced, construction period is saved, construction safety can be ensured, and good social benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, specifically to a method for constructing shallow-buried tunnels with an exposed arch above and a cut-and-cover excavation below. Background Technology

[0002] In recent years, with the rapid development of tunnel construction technology, tunnel cross-sections have become larger and larger, and geological conditions have become increasingly worse. In particular, in some ultra-shallow buried sections, the construction of large-section tunnels is not only difficult and slow, but also highly dangerous. For ultra-shallow buried sections, there are often buildings or structures passing through the surface or the geological conditions are poor, so the open-cut method is not allowed for large-scale excavation.

[0003] Due to the large tunnel cross-section during construction, the vertical excavation height required for open-cut excavation in shallow-buried tunnel construction is also large, resulting in large excavation slopes. This inevitably disturbs and damages the surrounding soil during excavation, and presents a series of challenges such as difficult open-cut concrete construction and large backfill volume. In addition, if the support of shallow-buried tunnels is not properly provided, there is a risk of collapse, which will affect the surface and surrounding environment. To address these issues, we propose a construction method of open-cut excavation above the arch and underground excavation below the arch for shallow-buried tunnels. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for constructing shallow-buried tunnels with an exposed arch above and a cut-and-cover excavation below, thereby solving the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a shallow-buried tunnel with an exposed arch above and a cut-and-cover excavation below, comprising the following steps:

[0006] S1. Leveling the gutter and excavating the slopes: After the gutter is leveled, the permanent slopes on both sides of the line are excavated and sprayed with grass for protection.

[0007] S2. Open-cut excavation of the arch: The arch is excavated using the open-cut method, and temporary slope support is constructed. The temporary slope support is carried out by anchor mesh shotcreting and mortar anchor bolts are installed.

[0008] S3. Construct arch support: Construct arch support, erect a steel frame, and install two 42 anchor pipes at each of the left and right arch feet, and pour cast-in-place concrete to protect the arch.

[0009] S4. Backfilling on the arch: After the arch support strength in step S3 reaches the design level, compact the soil and rock to the temporary backfill surface.

[0010] S5. Three-stage excavation with temporary invert: When the backfill soil and rock in step S4 restores the surface buildings (structures), the construction changes from open excavation on the arch to underground excavation under the arch. The tunnel body is excavated normally under the arch using the three-stage excavation with temporary invert method.

[0011] S6. Secondary Lining: After the excavation of the arch under the arch using a three-stage + temporary invert arch in step S5 is completed, the side walls and temporary supports are constructed, and the secondary lining concrete is applied.

[0012] S7. Laying the waterproof layer: After the secondary lining concrete in step S6 reaches the design strength, backfill the soil and rocks to the design elevation in a timely manner, and lay the clay waterproof layer to complete the construction.

[0013] To further optimize this technical solution, in step S2, the thickness of the shotcrete after the anchor mesh is shotcrete is 12-18cm, using 8 steel mesh with a mesh spacing of 20cm*20cm.

[0014] To further optimize this technical solution, in step S2, the diameter of the mortar anchor rod is 20-22cm, the length of the anchor rod is 3.5-4.0m, and the spacing between two adjacent anchor rods of the pre-embedded anchor rod is 1.0*1.0m.

[0015] To further optimize this technical solution, the steel frame in step S3 is an I20b type steel frame, and the spacing between the erected steel frames is 0.6m / frame. The length of the 42 locking foot anchor pipe in step S3 is 6.0m, and the longitudinal spacing is 0.6m.

[0016] To further optimize this technical solution, the concrete poured in step S3 is C25 concrete, and the thickness of the concrete is 100-110cm.

[0017] To further optimize this technical solution, in step S3, when erecting the steel frame, a steel frame joint of type I20b for arch protection is reserved so that it can be connected to the arch wall steel frame during the underground excavation under the arch.

[0018] To further optimize this technical solution, the height of the arch in step S4 is 3-4m, and the thickness of the clay waterproof layer in step S7 is 40-60cm.

[0019] To further optimize this technical solution, in step S2, anchor rods are installed in the poured concrete, then a steel mesh is laid along the excavated slope, and then concrete is sprayed along the surface of the steel mesh.

[0020] Compared with the prior art, the present invention provides a method for constructing shallow-buried tunnels with openwork construction on top and cut-and-cover excavation underneath, which has the following beneficial effects:

[0021] 1. This invention relates to a shallow-buried tunnel construction method that utilizes open-face construction above the arch and underground excavation below the arch. The method employs a three-stage approach with a temporary inverted arch for normal excavation of the tunnel body below the arch, ensuring construction safety and minimizing the impact on the surrounding environment. Based on rock mechanics theory, this method combines concrete pouring and anchor pipe support as the main support means to form a reinforced concrete rigid arch to complete the open-face construction above the arch. Under the protection of the reinforced concrete rigid arch, the tunnel body excavation below the arch is carried out, cleverly avoiding the risk of collapse. This method successfully solves the technical problem of high difficulty and susceptibility to collapse in shallow-buried large-section tunnel construction, and has broad application value.

[0022] 2. This invention relates to a shallow-buried tunnel construction method that uses open-cut construction above the arch and underground excavation below. In the construction of shallow-buried underpass tunnels, this method effectively controls surface settlement, protects surface buildings, prevents them from being affected by tunnel construction, avoids the need to demolish surface buildings, significantly saves construction time, and thus reduces costs. The tunnel's secondary lining structure is rationally designed, the construction method is simple, and the construction quality is easy to control, thereby greatly reducing construction costs, shortening the construction period, and ensuring construction safety, resulting in significant social benefits. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the construction method for shallow-buried tunnels, which involves excavation above the arch and underground excavation below the arch, as proposed in this invention.

[0024] Figure 2 This is a schematic diagram of the leveling trench and excavation slope structure for a shallow-buried tunnel construction method with openwork above the arch and underground excavation below the arch proposed in this invention.

[0025] Figure 3 This is a schematic diagram of the open-cut excavation arch structure of a shallow-buried tunnel construction method proposed in this invention, which involves excavating the arch from above and below the tunnel.

[0026] Figure 4 This is a schematic diagram of the arch support structure for a shallow-buried tunnel construction method with openwork above the arch and underground excavation below, as proposed in this invention.

[0027] Figure 5 This is a schematic diagram of the backfill surface structure on the arch of a shallow-buried tunnel construction method with open construction on the arch and underground excavation below the arch proposed in this invention.

[0028] Figure 6 This is a schematic diagram of a three-stage + temporary inverted arch excavation structure for a shallow-buried tunnel arch-arch-under-cutting construction method proposed in this invention.

[0029] Figure 7 This is a schematic diagram of the secondary lining and waterproof layer laying structure of a shallow-buried tunnel arch-excavation method proposed in this invention. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: Please refer to Figures 1 to 7 As shown, this invention discloses a method for constructing a shallow-buried tunnel with an exposed arch above and a cut-and-cover excavation below, comprising the following steps:

[0032] S1. Leveling the gutter and excavating the slopes: After the gutter is leveled, the permanent slopes on both sides of the line are excavated and sprayed with grass for protection.

[0033] S2. Open-cut excavation of the arch: The arch is excavated using the open-cut method. Temporary slope support is constructed, and the temporary slope support is carried out using anchor mesh shotcrete operation, with mortar anchors installed. The thickness of the shotcrete after the anchor mesh shotcrete is 12cm, using 8 steel mesh with a mesh spacing of 20cm*20cm. The diameter of the mortar anchor is 20cm, and the length of the anchor is 3.5m. The spacing between two adjacent anchors is 1.0*1.0m. Anchors are installed on the excavated slope, and then steel mesh is laid on the surface of the excavated slope, and then shotcrete is sprayed along the surface of the steel mesh.

[0034] S3. Construction of Arch Support: Construct arch support by erecting a steel frame and installing two 42 anchor pipes at each of the left and right arch feet. Pour cast-in-place concrete to protect the arch. The steel frame is an I20b type steel frame, and the spacing between the erected steel frames is 0.6m / frame. The length of the 42 anchor pipes is 6.0m, and the longitudinal spacing is 0.6m. The poured concrete is C25 concrete with a thickness of 100cm. When erecting the steel frame, a joint of the I20b type steel frame for the arch protection is reserved so that it can be connected to the arch wall steel frame during the underground excavation under the arch.

[0035] S4. Backfill surface on the arch: After the arch support strength in step S3 reaches the design level, compact the soil and rock to the temporary backfill surface.

[0036] S5. Three-stage excavation with temporary invert: When the backfill soil and rock in step S4 restores the surface structure, the construction changes from open excavation on the arch to underground excavation under the arch. The tunnel body is excavated normally under the arch using the three-stage excavation with temporary invert method.

[0037] S6. Secondary Lining: After the excavation of the arch under the arch using a three-stage + temporary invert arch in step S5 is completed, the side walls and temporary supports are constructed, and the secondary lining concrete is applied.

[0038] S7. Laying the waterproof layer: After the secondary lining concrete in step S6 reaches the design strength, backfill the soil and rocks to the design elevation in a timely manner, and lay the clay waterproof layer with a thickness of 40cm to complete the construction.

[0039] Example 2: Please refer to Figures 1 to 7 As shown, this invention discloses a method for constructing a shallow-buried tunnel with an exposed arch above and a cut-and-cover excavation below, comprising the following steps:

[0040] S1. Leveling the gutter and excavating the slopes: After the gutter is leveled, the permanent slopes on both sides of the line are excavated and sprayed with grass for protection.

[0041] S2. Open-cut excavation of the arch: The arch is excavated using the open-cut method. Temporary slope support is constructed, and the temporary slope support is carried out using anchor mesh shotcrete operation, with mortar anchors installed. The thickness of the shotcrete after the anchor mesh shotcrete is 15cm. 8 steel mesh is used, with a mesh spacing of 20cm*20cm. The diameter of the mortar anchor is 22cm, and the length of the anchor is 4.0m. The spacing between two adjacent anchors is 1.0*1.0m. Anchors are installed on the surface of the excavated slope, and then a steel mesh is laid on the surface of the excavated slope, followed by shotcrete along the surface of the steel mesh.

[0042] S3. Construction of Arch Support: Construct arch support by erecting a steel frame and installing two 42 anchor pipes at each of the left and right arch feet. Pour cast-in-place concrete to protect the arch. The steel frame is an I20b type steel frame, and the spacing between the erected steel frames is 0.6m / frame. The length of the 42 anchor pipes is 6.0m, and the longitudinal spacing is 0.6m. The poured concrete is C25 concrete with a thickness of 100cm. When erecting the steel frame, a joint of the I20b type steel frame for the arch protection is reserved so that it can be connected to the arch wall steel frame during the underground excavation under the arch.

[0043] S4. Backfill surface on the arch: After the arch support strength in step S3 reaches the design level, compact the soil and rock to the temporary backfill surface.

[0044] S5. Three-stage excavation with temporary invert: When the backfill soil and rock in step S4 restores the surface buildings (structures), the construction changes from open excavation on the arch to underground excavation under the arch. The tunnel body is excavated normally under the arch using the three-stage excavation with temporary invert method.

[0045] S6. Secondary Lining: After the excavation of the arch under the arch using a three-stage + temporary invert arch in step S5 is completed, the side walls and temporary supports are constructed, and the secondary lining concrete is applied.

[0046] S7. Laying the waterproof layer: After the secondary lining concrete in step S6 reaches the design strength, backfill the soil and rocks to the design elevation in a timely manner, and lay the clay waterproof layer with a thickness of 50cm to complete the construction.

[0047] Example 3: Please refer to Figures 1 to 7 As shown, this invention discloses a method for constructing a shallow-buried tunnel with an exposed arch above and a cut-and-cover excavation below, comprising the following steps:

[0048] S1. Leveling the gutter and excavating the slopes: After the gutter is leveled, the permanent slopes on both sides of the line are excavated and sprayed with grass for protection.

[0049] S2. Open-cut excavation of the arch: The arch is excavated using the open-cut method. Temporary slope support is constructed, and the temporary slope support is carried out using anchor mesh shotcrete operation, with mortar anchors installed. The thickness of the shotcrete after the anchor mesh shotcrete is 16cm, using 8 steel mesh with a mesh spacing of 20cm*20cm. The diameter of the mortar anchor is 22cm, and the length of the anchor is 3.8m. The spacing between two adjacent anchors is 1.0*1.0m. Mortar anchors are installed on the excavated slope, and then steel mesh is laid on the surface of the excavated slope, followed by shotcrete along the surface of the steel mesh.

[0050] S3. Construction of Arch Support: Construct arch support by erecting a steel frame and installing two 42 anchor pipes at each of the left and right arch feet. Pour cast-in-place concrete to protect the arch. The steel frame is an I20b type steel frame, and the spacing between the erected steel frames is 0.6m / frame. The length of the 42 anchor pipes is 6.0m, and the longitudinal spacing is 0.6m. The poured concrete is C25 concrete with a thickness of 100cm. When erecting the steel frame, a joint of the I20b type steel frame for the arch protection is reserved so that it can be connected to the arch wall steel frame during the underground excavation under the arch.

[0051] S4. Backfill surface on the arch: After the arch support strength in step S3 reaches the design level, compact the soil and rock to the temporary backfill surface.

[0052] S5. Three-stage excavation with temporary invert: When the backfill soil and rock in step S4 restores the surface buildings (structures), the construction changes from open excavation on the arch to underground excavation under the arch. The tunnel body is excavated normally under the arch using the three-stage excavation with temporary invert method.

[0053] S6. Secondary Lining: After the excavation of the arch under the arch using a three-stage + temporary invert arch in step S5 is completed, the side walls and temporary supports are constructed, and the secondary lining concrete is applied.

[0054] S7. Laying the waterproof layer: After the secondary lining concrete in step S6 reaches the design strength, backfill the soil and rocks to the design elevation in a timely manner, and lay the clay waterproof layer with a thickness of 60cm to complete the construction.

[0055] Judgment criteria: Through comparison of the three embodiments, the second embodiment has the best effect. Therefore, the second embodiment is selected as the best embodiment. The specific changes in quantity also fall within the scope of protection of this technical solution.

[0056] The beneficial effects of this invention are as follows: This shallow-buried tunnel construction method, which involves open construction above the arch and underground excavation below, transforms the construction from open construction above the arch to underground excavation below the arch. The underground excavation employs a three-stage method with a temporary invert arch for normal tunnel excavation, ensuring construction safety and reducing the impact on the surrounding environment. Based on rock mechanics theory, this method combines poured concrete and anchor pipe support as the main support means to form a reinforced concrete rigid arch to complete the open construction above the arch. Under the protection of the reinforced concrete rigid arch, the tunnel excavation below the arch is carried out, cleverly avoiding the risk of collapse and successfully resolving the problem. This invention solves the technical challenge of high difficulty and susceptibility to collapse in the construction of shallow-buried large-section tunnels, and has broad application value. In the construction of shallow-buried underpass tunnels, this invention effectively controls surface settlement, protects ground buildings, and prevents them from being affected by tunnel construction, thus avoiding the need to demolish ground buildings, greatly saving construction time and costs. The secondary lining structure of the tunnel is reasonably designed and the construction method is simple and the construction quality is easy to control, thereby significantly reducing construction costs, shortening the construction period, and ensuring construction safety, resulting in good social benefits.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A construction method for shallow-buried tunnels, characterized by open-cut construction above the arch and underground excavation below, wherein... Includes the following steps: S1. Leveling the gutter and excavating the slopes: After the gutter is leveled, the permanent slopes on both sides of the line are excavated and sprayed with grass for protection. S2. Open-cut excavation of the arch: The arch is excavated using the open-cut method, and temporary slope support is constructed. The temporary slope support is carried out by anchor mesh shotcreting and mortar anchor bolts are installed. S3. Construct arch support: Construct arch support, erect a steel frame, and install two 42 anchor pipes at each of the left and right arch feet, and pour cast-in-place concrete to protect the arch. S4. Backfill surface on the arch: After the arch support strength in step S3 reaches the design level, compact the soil and rock to the temporary backfill surface. S5. Three-stage excavation with temporary invert: When the backfill soil and rock in step S4 restores the surface buildings, the construction changes from open excavation on the arch to underground excavation under the arch. The tunnel body is excavated normally under the arch using the three-stage excavation with temporary invert method. S6. Secondary Lining: After the excavation of the arch under the arch using a three-stage + temporary invert arch in step S5 is completed, the side walls and temporary supports are constructed, and the secondary lining concrete is applied. S7. Laying the waterproof layer: After the secondary lining concrete in step S6 reaches the design strength, backfill the soil and rocks to the design elevation in a timely manner, and lay the clay waterproof layer to complete the construction.

2. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... In step S2, the thickness of the shotcrete after the anchor mesh is 12-18cm, using 8 steel mesh with a mesh spacing of 20cm*20cm.

3. The construction method for shallow-buried tunnels with open-cut arch construction above and cut-and-cover excavation below, as described in claim 1, is characterized in that... In step S2, the diameter of the mortar anchor is 20-22cm, the length of the anchor is 3.5-4.0m, and the spacing between two adjacent mortar anchors is 1.0*1.0m.

4. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... The steel frame in step S3 is an I20b type steel frame, and the spacing between the erected steel frames is 0.6m / frame. The length of the 42 locking foot anchor pipe in step S3 is 6.0m, and the longitudinal spacing is 0.6m.

5. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... The concrete poured in step S3 is C25 concrete, and the thickness of the concrete is 100-110cm.

6. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... In step S3, during the erection of the steel frame, a joint for the I20b type steel frame of the arch support is reserved so that it can be connected to the arch wall steel frame during the underground excavation under the arch.

7. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... In step S4, the height of the arch is 3-4m, and in step S7, the thickness of the clay waterproof layer is 40-60cm.

8. The construction method for shallow-buried tunnels with open-cut construction above the arch and underground excavation below, as described in claim 1, is characterized in that... In step S2, anchor bolts are installed in the excavated slope, then steel mesh is laid on the surface of the excavated slope, and then concrete is sprayed along the surface of the steel mesh.

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