Construction method of assembled shed tunnel structure

Abstract

The invention discloses a construction method of an assembled shed tunnel structure. A conventional slope collapse prevention open cut tunnel structure of a railway does not bear lateral soil pressure on the slope side theoretically and is not suitable for sections with serious bias pressure. The method comprises the following steps: constructing a hole-digging anchoring pile and a hole-digging filling pile; formwork-erecting cast-in-place bearing platform beams and formwork-erecting cast-in-place concrete walls; hoisting breast boards in a layered manner, synchronously placing sand and pebble inverted filter layers in a layered manner, synchronously compacting and backfilling soil and stones in a layered manner, and casting top beams in situ; installing a top plate in the skylight time of railway operation; soil and stones are compacted and backfilled to the top surface of the top beam layer by layer; an EVA waterproof plate is laid; a concrete water-resisting layer is cast in place; filling, layered rolling and backfilling of soil and stones; and in combination with terrain and hydrological conditions, a drainage ditch is excavated and arranged on the top surface of the backfilled soil stone. The method solves the problem that the conventional open cut tunnel construction seriously affects the operation of the existing railway, and also solves the problem that the conventional open cut tunnel cannot bear a larger load on the side close to the mountain.

Description

Technical Field

[0002] This invention belongs to the field of geological disaster prevention and control technology, and specifically relates to a construction method for a prefabricated tunnel structure. Background Technology

[0003] The section of the Longhai Railway's northbound line from Baoji to Tianshui, between K1350+470.7 and K1350+484, is located between the exit of the Pingshan Tunnel and the entrance of the Lanshan Tunnel, with a length of 13.3 meters. The railway project, situated at a geological disaster site, is located along a river and beside a mountain. The mountainside is a loess slope with a height exceeding 50 meters. Under the influence of continuous heavy rainfall, the soil softened, its shear strength decreased, and the hydrostatic and hydrodynamic pressures increased. On August 17, 2020, the top of the natural slope collapsed, and the debris accumulated on the railway track, causing the Longhai Railway's northbound line to be suspended.

[0004] The loess slope at the disaster site is over 50 meters high and could still collapse under heavy rainfall, requiring thorough remediation. Using conventional slope protection structures at this site would be extremely difficult; therefore, a tunnel or open-cut structure was proposed to shield the railway from the impact of landslide debris.

[0005] Conventional open-cut tunnel structures for railways to prevent slope collapse, such as Figure 5 As shown, the formwork pouring for the upper concrete arch of the tunnel has a significant impact on railway operations. The Longhai Railway's northbound line is a national trunk line and cannot be suspended due to disaster mitigation work. Disaster mitigation work can only be carried out during 1-3 hour / day maintenance windows, making it difficult to guarantee a 3-month construction period. At this landslide site, a 6-10m layer of fill needs to be placed on the mountainside of the tunnel or shed, resulting in high lateral earth pressure and severe bias pressure. Conventional railway tunnel structures designed to prevent slope collapses theoretically cannot withstand lateral earth pressure from the slope and are unsuitable for areas with severe bias pressure. These two points determine that conventional railway tunnel structures designed to prevent slope collapses are unsuitable for mitigating this landslide hazard. Developing a suitable engineering protection structure is therefore crucial. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a construction method for a prefabricated tunnel structure. For small components used in railway operations, reinforced concrete is cast in place, while for large components used in railway operations, reinforced concrete is prefabricated off-site. The prefabricated components are then hoisted and assembled. The constructed prefabricated tunnel structure can withstand lateral earth pressure and is suitable for areas with severe eccentric pressure. This solves the problem that conventional open-cut tunnel construction seriously affects the operation of existing railways, and also addresses the issue that conventional open-cut tunnels cannot withstand large loads on the mountainside.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A construction method for a prefabricated shed structure includes the following steps: Step 1: Construct bored anchor piles and bored cast-in-place piles; Step 2: After the steel reinforcement cage of the pier cap beam is installed in place, the formwork is erected and the pier cap beam is cast in place; Step 3: Erect formwork and cast in-situ concrete walls to complete the construction of the outer walls of the prefabricated shed opening; Step 4: Precast retaining walls and roof slabs; Step 5: Install retaining walls in layers, simultaneously place sand and gravel filter layers in layers, and simultaneously compact backfill soil and rock in layers; Step Six: After the retaining wall, sand and gravel filter layer, and backfill soil and rock are constructed to the top surface of the retaining wall, the steel cage for the capping beam is placed and the capping beam is cast in place; Step 7: Install the roof slab during the railway's maintenance window. Step 8: Compact the backfill soil and rock in layers up to the top surface of the cap beam; Step 9: Lay the EVA waterproof membrane; Step 10: Cast-in-place concrete waterproof layer; Step 11: Fill and compact the backfill soil and rock in layers; Step 12: Based on the terrain and hydrological conditions, excavate and construct drainage ditches on the top surface of the backfill soil and rocks.

[0008] Furthermore, step one specifically includes: Due to the proximity of railway construction to operations and the lack of conditions for blasting and excavating rocks, a combination of manual labor and pneumatic picks was used to excavate the pile holes for bored anchor piles and bored cast-in-place piles, hoist the reinforcing cages, and then pour the concrete for the bored anchor piles and bored cast-in-place piles.

[0009] Furthermore, the prefabricated shed structure constructed according to the aforementioned construction method is specifically as follows: A pile-slab retaining wall is installed on the mountainside of the railway, and an outer wall of a prefabricated tunnel structure is installed on the mountainside of the railway. A top slab is installed on top of the pile-slab retaining wall and the outer wall; The pile-slab retaining wall includes bored anchor piles and retaining plates, and a capping beam is provided on the top of the bored anchor piles; The outer wall includes bored cast-in-place piles, with a foundation beam at the top of the bored cast-in-place piles, and a concrete wall at the top of the foundation beam.

[0010] Furthermore, a sand-pebble filter layer is provided on the back side of the retaining plate.

[0011] Furthermore, an EVA waterproof membrane is provided on the top plate.

[0012] Furthermore, a concrete waterproof layer is provided on the EVA waterproof board.

[0013] Furthermore, backfill soil and rocks are installed on the inner and upper sides of the prefabricated shed.

[0014] Furthermore, the bored anchor piles and the capping beam are made of cast-in-place reinforced concrete, while the retaining plate is made of precast reinforced concrete.

[0015] Furthermore, the EVA waterproofing membrane and concrete waterproofing layer are laid from the inside of the mountain to the outer wall of the shed.

[0016] Furthermore, the crown beam is provided with a tongue and groove joint on the side facing the railway, and the concrete wall is provided with a tongue and groove joint on the side facing the railway.

[0017] The beneficial effects of this invention are: 1) The prefabricated tunnel structure constructed by this invention can withstand lateral earth pressure and is suitable for areas with severe eccentric pressure. It solves the problem that conventional open-cut tunnel construction seriously affects the operation of existing railways, and at the same time solves the problem that conventional open-cut tunnels cannot withstand large loads on the mountain side. 2) This invention uses cast-in-place reinforced concrete for small components used in railway operations, and prefabricates reinforced concrete off-site for large components used in railway operations. The prefabricated components are then hoisted and assembled, which improves construction efficiency. Attached Figure Description

[0018] Figure 1 This is a plan view of the assembled shed of the present invention; Figure 2 This is a cross-sectional view of the present invention (AA section). Figure 3 This is a cross-sectional view of the present invention (BB). Figure 4 This is a CC cross-sectional view of the present invention; Figure 5 This is a structural diagram of a conventional railway tunnel designed to prevent slope collapse. In the diagram: 1-Drilled anchor pile, 2-Drilled cast-in-place pile, 3-Pile cap beam, 4-Cover beam, 5-Concrete wall, 6-Retaining plate, 7-Top plate, 8-Sand and gravel filter layer, 9-EVA waterproof membrane, 10-C20 concrete waterproof layer, 11-Backfill soil and rock. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments.

[0020] This invention provides a construction method for a prefabricated tunnel structure. For small components used in railway operations, reinforced concrete is cast in place, while for large components used in railway operations, reinforced concrete is prefabricated off-site. The prefabricated components are then hoisted and assembled. The constructed prefabricated tunnel structure can withstand lateral earth pressure and is suitable for areas with severe eccentric pressure. This solves the problem that conventional open-cut tunnel construction seriously affects the operation of existing railways, and also addresses the issue that conventional open-cut tunnels cannot withstand large loads on the mountainside.

[0021] This invention provides a construction method for a prefabricated shed structure, comprising the following steps: Step 1: Construct bored anchor pile 1 and bored cast-in-place pile 2, specifically as follows: Due to the proximity of railway construction to operations and the lack of conditions for blasting and excavating rocks, a combination of manual labor and pneumatic picks was used to excavate the pile holes for bored anchor piles and bored cast-in-place piles, hoist the reinforcing cages, and then pour the concrete for the bored anchor piles and bored cast-in-place piles.

[0022] Step 2: After the steel reinforcement cage of the foundation beam 3 is installed in place, erect the formwork and cast the foundation beam 3 in place; Step 3: Erect formwork and cast in-situ concrete wall 5 to complete the construction of the outer wall of the prefabricated shed opening; Step 4: In a flat area near the disease site, prefabricate retaining wall 6 and top slab 7; Step 5: Install retaining walls 6 in layers, simultaneously place sand and gravel filter layer 8 in layers, and simultaneously use small machinery to compact backfill soil and rock 11 in layers; Step 6: After the retaining wall 6, sand and gravel filter layer 8, and backfill soil and rock 11 are constructed to the top surface of the retaining wall 6, the steel cage of the capping beam 4 is placed and the capping beam 4 is cast in place. Step 7: During the railway's maintenance window, use cables or cranes to install the top slab 7 in a step-by-step manner. The installed top slab 7 provides the site for subsequent installations, and the main structure of the prefabricated tunnel is completed. Step 8: Use small machinery to compact the backfill soil and rock 11 to the top surface of the capping beam 4 in layers; Step 9: Lay EVA waterproof membrane 9, extending from 0.5m inside the mountain to the outer wall of the shed; Step 10: Cast a C20 concrete waterproof layer 10 in place, with the casting range extending from 0.5m inside the mountain to the outer wall of the shed. Step 11: Fill and compact the backfill soil and rock in layers 11; Step 12: Based on the terrain and hydrological conditions, excavate and set up a drainage ditch at the top of the backfill soil and rock 11 to drain the rainwater collected on the hillside.

[0023] like Figure 1 , 2 As shown in Figures 3 and 4, the prefabricated shed structure constructed according to the construction method of this invention is specifically as follows: A pile-slab retaining wall is installed on the mountainside of the railway, and an outer wall of a prefabricated tunnel structure is installed on the mountainside of the railway. A top slab 7 is installed on top of the pile-slab retaining wall and the outer wall; the top slab 7 serves as the roof of the prefabricated shed structure, with a width of 1 to 1.3 meters, and is prefabricated off-site with reinforced concrete, and then hoisted after prefabrication. The pile-slab retaining wall can withstand the soil pressure on the mountain side, and at the same time, the pile-slab retaining wall serves as the inner side wall of the prefabricated shed structure; the pile-slab retaining wall and the outer side wall provide support for the reinforced concrete roof slab 7 of the prefabricated shed. The pile-slab retaining wall includes bored anchor piles 1 and retaining plates 6. The top of the bored anchor piles 1 is provided with a capping beam 4; the back side of the retaining plates 6 is provided with a bagged sand and gravel filter layer 8.

[0024] The outer wall includes bored piles 2, with a pile cap beam 3 on top of the bored piles 2, and a C30 concrete wall 5 on top of the pile cap beam 3. The bored piles 2 and the pile cap beam 3 provide a stable foundation for the concrete wall 5. The bored piles 2, the pile cap beam 3 and the concrete wall 5 are all made of reinforced concrete or cast-in-place concrete.

[0025] An EVA waterproof membrane 9 is installed on the top slab 7, and a 30cm thick C20 concrete waterproof layer 10 is installed on the EVA waterproof membrane 9. The EVA waterproof membrane and the concrete waterproof layer can prevent rainwater from seeping into the shed. Backfill soil and rocks 11 are installed on the inner and upper sides of the prefabricated shed. The EVA waterproof membrane 9 and the concrete waterproof layer 10 are laid from 0.5m inside the hillside to the outer wall of the shed.

[0026] The bored anchor pile 1 and the capping beam 4 are made of cast-in-place reinforced concrete, while the retaining plate 6 is made of precast reinforced concrete and is hoisted after prefabrication. The capping beam 4 and the concrete wall 5 are equipped with tongue and groove joints on the side facing the railway to facilitate the installation of the top plate 7.

[0027] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.

Claims

1. A construction method for a prefabricated shed structure, characterized in that: Includes the following steps: Step 1: Construct bored anchor piles (1) and bored cast-in-place piles (2); Step 2: After the steel cage of the pier beam (3) is installed in place, the pier beam (3) is cast in place using the formwork. Step 3: Erect formwork and cast in-situ concrete wall (5) to complete the construction of the outer wall of the assembled shed; Step 4: Precast retaining wall (6) and top slab (7); Step 5: Install retaining walls in layers (6), simultaneously place sand and gravel filter layer in layers (8), and simultaneously compact backfill soil and rock in layers (11); Step 6: After the retaining wall (6), sand and gravel filter layer (8), and backfill soil and rock (11) are constructed to the top surface of the retaining wall (6), the steel cage of the cap beam (4) is placed and the cap beam (4) is cast in place. Step 7: Install the top plate (7) during the railway operation window. Step 8: Compact the backfill soil and rock (11) in layers up to the top surface of the cap beam (4); Step 9: Lay the EVA waterproof board (9); Step 10: Cast-in-place concrete waterproof layer (10); Step 11: Fill and compact the backfill soil and rock in layers (11); Step 12: Based on the terrain and hydrological conditions, excavate and set up a drainage ditch on the top surface of the backfill soil and rock (11).

2. The construction method of a prefabricated shed structure according to claim 1, characterized in that: Step one specifically involves: Due to the proximity of railway construction to operations and the lack of conditions for blasting and excavating rocks, a combination of manual labor and pneumatic picks was used to excavate the pile holes for bored anchor piles and bored cast-in-place piles, hoist the reinforcing cages, and then pour the concrete for the bored anchor piles and bored cast-in-place piles.

3. The construction method of a prefabricated shed structure according to claim 2, characterized in that: The prefabricated shed structure constructed according to the aforementioned construction method is specifically as follows: A pile-slab retaining wall is installed on the mountainside of the railway, and an outer wall of a prefabricated tunnel structure is installed on the mountainside of the railway. A top slab (7) is provided on the pile-slab retaining wall and the outer side wall. The pile-slab retaining wall includes bored anchor piles (1) and retaining plates (6), and a capping beam (4) is provided on the top of the bored anchor piles (1). The outer wall includes bored piles (2), and a pile cap beam (3) is provided on the top of the bored piles (2), and a concrete wall (5) is provided on the top of the pile cap beam (3).

4. The construction method of a prefabricated shed structure according to claim 3, characterized in that: The back side of the retaining plate (6) is provided with a sand and gravel filter layer (8).

5. The construction method of a prefabricated shed structure according to claim 4, characterized in that: An EVA waterproof membrane (9) is provided on the top plate (7).

6. The construction method of a prefabricated shed structure according to claim 5, characterized in that: A concrete waterproof layer (10) is provided on the EVA waterproof board (9).

7. The construction method of a prefabricated shed structure according to claim 6, characterized in that: Backfill soil and rocks are placed on the inner and upper sides of the prefabricated shed (11).

8. The construction method of a prefabricated shed structure according to claim 7, characterized in that: The bored anchor piles (1) and the capping beam (4) are made of cast-in-place reinforced concrete, while the retaining plate (6) is made of precast reinforced concrete.

9. The construction method of a prefabricated shed structure according to claim 8, characterized in that: The EVA waterproofing membrane (9) and the concrete waterproofing layer (10) are laid from the inside of the mountain to the outside wall of the cave.

10. The construction method of a prefabricated shed structure according to claim 9, characterized in that: The crown beam (4) has a tongue and groove joint on the side facing the railway, and the concrete wall (5) has a tongue and groove joint on the side facing the railway.

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