An abutment and a method of construction thereof

Abstract

The present application relates to an arch seat and a construction method thereof. The arch seat comprises an embedding segment, a force transmission segment and a connecting segment arranged in sequence along the length direction of the arch seat, the embedding segment is located within the unloading zone of the slope, the force transmission segment is located between the unloading zone and the excavation slope surface of the slope, and the connecting segment is located outside the excavation slope surface. The embedding segment, the force transmission segment and the connecting segment are integrally formed as a reinforced concrete structure, and the connecting segment is used to connect the arch foot of the main arch. According to the unloading zone and the excavation slope surface of the slope, the embedding segment of the arch seat is embedded into the stable rock layer within the unloading zone, and the load of the main arch is borne through the connecting segment after the force transmission segment passes through the unloading zone and the excavation slope surface. Compared with the reinforced concrete expanded arch seat, the cross-sectional size of the structure is smaller, the anchoring capacity is good, the excavation range is small, the risk is smaller, and the applicability is higher when the slope at the bridge site is relatively steep and there is a poor geological condition of unloading fracture development in the steep slope.

Description

Technical Field

[0001] This invention relates to the field of arch seat technology, and in particular to an arch seat and its construction method. Background Technology

[0002] As my country's highway construction extends into the western mountainous regions, long-span bridges are increasingly used to cross mountain valleys, with arch bridges being widely adopted due to their economic efficiency, high load-bearing capacity, and strong spanning ability. However, in the southwestern mountainous areas, the construction of long-span bridges faces complex terrain and geological conditions. Constrained by these adverse geological conditions, conventional arch abutment foundation structures are ill-suited to the construction needs, necessitating the development of a new type of arch abutment foundation adapted to complex terrain and geological conditions.

[0003] Existing arch foundation structures all employ reinforced concrete enlarged arch abutments. These abutments are set on the foundation rock mass. To ensure sufficient bearing area at the abutment base to resist the internal forces transmitted from the superstructure of the arch bridge, the dimensions of these abutments must be sufficiently large to meet the foundation stress requirements. However, the large dimensions of existing reinforced concrete enlarged arch abutment structures mean that when the slope at the bridge site is relatively steep, the construction of the abutments set on the foundation rock mass requires a large amount of slope excavation. For steep slopes with unloading fissures or bedding slopes and other adverse geological conditions, large excavations can easily lead to slope instability and create significant geological risks. Summary of the Invention

[0004] The purpose of this invention is to address the problem that existing reinforced concrete enlarged arch supports have large structural dimensions and pose significant risks when the slope at the bridge site is steep and there are geological conditions such as poor unloading crack development. This invention provides an arch support and its construction method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An arch abutment includes a fixed section, a force-transmitting section, and a connecting section arranged sequentially along its length. The fixed section is located within the unloading zone of a slope, the force-transmitting section is located between the unloading zone and the excavated slope surface of the slope, and the connecting section is located outside the excavated slope surface. The fixed section, the force-transmitting section, and the connecting section are integrally formed reinforced concrete structures, and the connecting section is used to connect the arch foot of the main arch.

[0007] The length direction of the arch seat is the same as or at a certain angle to the axial direction of the arch foot of the main arch. The smaller the angle, the stronger the ability to resist the superstructure. The angle can be set according to actual needs.

[0008] The arch abutment described in this scheme has an embedded section located within the unloading zone of the slope, anchored to the rock within the unloading zone, providing the main resistance of the entire arch abutment with the help of the rock within the unloading zone. The connecting section is located outside the excavated slope surface, mainly connecting to the arch foot, facilitating the connection between the arch foot and the arch abutment, and preventing the arch foot from entering between the unloading zone and the excavated slope surface, thus avoiding direct impact of the soil between the unloading zone and the excavated slope surface on the main arch. The force transmission section is located between the unloading zone and the excavated slope surface, serving as a path for the embedded section to provide resistance to the connecting section. Furthermore, when the soil between the unloading zone and the excavated slope surface is stable, the force transmission section can also provide some resistance to the connecting section, but this resistance is not very stable. The arch abutment described in this scheme, based on the unloading zone of the slope and the excavation slope surface, allows the fixed section of the arch abutment to be embedded in the stable rock layer within the unloading zone. After the force transmission section passes through the unloading zone and the excavation slope surface, it bears the load of the main arch through the connecting section. Compared with reinforced concrete enlarged arch abutments, its cross-sectional dimensions are smaller, but its anchoring capacity is better. When the slope at the bridge site is relatively steep and there are steep slopes with poorly developed unloading cracks, its excavation range is smaller, its use risk is lower, and its applicability is higher.

[0009] Preferably, the cross-section of the arch seat gradually changes along the length direction of the arch seat, and the inner end face dimension of the embedded section is larger than the outer end face dimension of the connecting section;

[0010] or,

[0011] The cross-sections of the arches are equal.

[0012] When the cross-section of the arch abutment gradually changes along its length, with a larger inner end and a smaller outer end, it has better load-bearing capacity compared to a uniform cross-section. Furthermore, the load-transfer section can be made smaller, thus reducing the impact on the arch abutment when the soil between the unloading zone and the excavated slope surface is unstable. Conversely, when the arch abutment has a uniform cross-section along its length, construction is more convenient compared to a gradually changing cross-section.

[0013] Preferably, the height of the cross-section of the arch seat gradually changes along the length of the arch seat, which facilitates construction, reduces the longitudinal excavation size of the slope, and reduces risks.

[0014] Preferably, an isolation layer is provided on the outer side of the force transmission section. The isolation layer can deform along with the deformation of the rock mass between the unloading zone and the excavation slope. When the rock mass between the unloading zone and the excavation slope deforms, the deformation of the isolation layer can prevent it from affecting the force transmission section. That is, the isolation layer separates the force transmission section and the unloading zone from the rock mass between the excavation slope, so that they do not interfere with each other. This avoids the rock mass deformation directly affecting the rigid stress of the arch seat, which can significantly reduce the amount of excavation of the arch seat slope and make the arch seat reasonably stressed, reducing the impact of the rock mass between the unloading zone and the excavation slope on the arch seat.

[0015] Preferably, the insulating layer is a rigid polyurethane foam layer.

[0016] Preferably, the elastic modulus of the isolation layer is 1%-10% of the elastic modulus of the concrete in the force transmission section.

[0017] Preferably, the cross-section of the arch seat has an upward-arching circular arc at the top and a square bottom, which can provide support for the top of the arch seat.

[0018] Preferably, the top of the arch seat is provided with prestressed tendons along its length. Because the anchor body arch seat is adapted to the oblique arrangement of the arch foot, the prestressing at the top avoids the stress of tension at the upper end and compression at the lower end under the weight of the connecting section during construction, so that the connecting section is always under compression.

[0019] A method for constructing an arch seat, comprising the arch seat, wherein the construction of the arch seat includes the following steps:

[0020] S1. Excavate the slope at the location of the arch seat to form a construction platform;

[0021] S2. Based on the construction platform, at the location of the arch seat, along the length of the arch seat, first excavate the slope of the corresponding force transmission section from the surface of the excavation slope inward and support it to form the pouring space of the force transmission section. Then, excavate the slope of the corresponding embedment section and support it to form the pouring space of the embedment section.

[0022] S3, Reinforcing steel bars for arch abutments;

[0023] S4. Pour the concrete for the embedded section and the force transmission section in layers from the inside out. When the poured concrete reaches the excavation slope, set up the formwork for the corresponding connecting section, and then pour the connecting section. The arch seat is then completed.

[0024] In this design, the arch abutment is inclined relative to the slope and is not horizontal. To facilitate construction, the slope excavation forms a construction platform, eliminating the need for extensive slope excavation as required by existing reinforced concrete arch abutment construction techniques. This design prevents slope instability, especially on steep slopes with poorly developed unloading cracks, making construction safer. The construction platform also provides a better site for subsequent pouring, reducing the difficulty of excavating the pouring space and forming the arch abutment. Since the connecting section of the arch abutment is located outside the excavated slope surface, the pouring space for the force transmission section and the embedding section is excavated inwards along the slope surface. This excavation and support method ensures safety during excavation and subsequent pouring. Furthermore, the support can become part of the arch abutment after pouring, reinforcing it. After the reinforcing steel bars of the arch seat are laid, concrete is poured in layers from the inside out to ensure the compactness of the pouring and improve the quality of the arch seat pouring. Since the pouring space of the force transmission section and the embedded section is supported, the surrounding rock mass of the pouring space can be used as the pouring template to directly complete the pouring of the force transmission section and the embedded section. However, the connecting section is located outside the excavation slope, so the template of the connecting section needs to be erected first, and then the connecting section is poured, and the arch seat can be poured.

[0025] The construction method for the arch abutment described in this scheme requires minimal excavation of the slope surface to form the construction platform in the early stage. Furthermore, the casting space for the load-transfer and embedment sections is created by excavating tunnels, with simultaneous excavation and support. This ensures that even on steep slopes with poorly developed unloading cracks, slope instability can be avoided, making construction safer. Additionally, the surrounding slope of the casting space is used as a template for casting the embedment and load-transfer sections, allowing the cast-in-place sections to be directly embedded within the original slope's unloading zone, resulting in improved load-bearing capacity for the entire arch abutment.

[0026] Preferably, in step S2, when excavating the slope and supporting it to form the pouring space of the force transmission section, it is also necessary to excavate the filling space of the isolation layer radially outward; and after excavating the slope of the corresponding embedded section and supporting it to form the pouring space of the embedded section, it is also necessary to fill the filling space.

[0027] In step S3, prestressing tendons also need to be pre-embedded along the length direction of the top of the arch seat;

[0028] In step S4, the connecting section is divided into a pre-cast section and a post-cast section for pouring. When the poured concrete reaches the excavation slope, the formwork for the pre-cast section is erected and then the pre-cast section is poured. When the strength of the poured concrete reaches 80% of the design strength, the prestressing tendons are tensioned at one end of the pre-cast section, and then the formwork for the post-cast section is erected and the post-cast section is poured.

[0029] When excavating the slope and supporting it to form the pouring space for the force transmission section, an isolation layer is excavated at the same time to facilitate the setting of the support. After excavating the slope corresponding to the embedded section and supporting it to form the pouring space for the embedded section, the filling space is filled first, so that the isolation layer formed by the filling can serve as the pouring template for the force transmission section. It can be completely separated from the surrounding slope of the pouring space of the force transmission section during the pouring of the force transmission section, avoiding contact. This can prevent the surrounding slope of the pouring space of the force transmission section from affecting the force transmission section, and thus avoid adverse effects on the bearing capacity of the arch seat.

[0030] This scheme also involves the setting of prestressing tendons. By dividing the connection section into a pre-cast section and a post-cast section for pouring, the prestressing tendons can be tensioned in advance after the pre-cast section is completed, so that the connection section is in a state of compression in advance. This ensures that the prestressing tendons are located inside the arch abutment when the post-cast section is poured.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. The arch seat described in this invention, based on the unloading zone of the slope and the excavated slope surface, allows the fixed section of the arch seat to be embedded in the stable rock layer within the unloading zone. After the force transmission section passes through the unloading zone and the excavated slope surface, it bears the load of the main arch through the connecting section. Compared with reinforced concrete enlarged arch seats, its cross-sectional dimensions are smaller, but its anchoring capacity is better. When the slope at the bridge site is relatively steep and there are steep slopes with poor geological conditions such as unloading cracks, its excavation range is smaller, the use risk is lower, and its applicability is higher.

[0033] 2. The arch seat of the present invention has an isolation layer set on the outside of the force transmission section. When the rock mass between the unloading zone and the excavated slope deforms, the deformation of the isolation layer can avoid direct impact on the force transmission section. That is, the isolation layer separates the force transmission section and the unloading zone from the rock mass between the excavated slope, so that they do not interfere with each other. This avoids the rock mass deformation from directly affecting the rigid stress of the arch seat, which can significantly reduce the amount of excavation of the arch seat slope and make the arch seat reasonably stressed, reducing the impact of the rock mass between the unloading zone and the excavated slope on the arch seat.

[0034] 3. Because the anchor body arch seat is adapted to the arch foot to form an oblique arrangement, prestressing is provided at the top to avoid the stress of the upper end being under tension and the lower end being under compression under its own weight during construction. The arch seat of the present invention is provided with prestressing tendons along its length at the top, so that the connecting section is always under compression.

[0035] 4. The construction method of the arch seat described in this invention involves a small amount of excavation in the early stage to form a construction platform on the slope. Furthermore, the casting space for the force transmission section and the embedding section is constructed by excavating tunnels, with simultaneous excavation and support. This ensures that even on steep slopes with poorly developed unloading cracks, slope instability can be avoided, making construction safer. Additionally, the surrounding slope of the casting space is used as a template for casting the embedding and force transmission sections, allowing the cast-in-place sections to be directly embedded within the unloading zone of the original slope, resulting in better load-bearing capacity of the entire arch seat.

[0036] 5. The construction method of the arch abutment described in this invention allows the pre-filled isolation layer to serve as a casting template for the force transmission section. This layer completely separates the force transmission section from the surrounding slopes of the casting space during casting, preventing contact and thus avoiding any impact from the surrounding slopes on the force transmission section, thereby preventing adverse effects on the arch abutment's load-bearing capacity. By dividing the connecting section into pre-cast and post-cast sections, the prestressing tendons can be pre-tensioned after the pre-cast section is completed, placing the connecting section under compression beforehand. This ensures that the prestressing tendons remain inside the arch abutment during the post-cast section. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the arch seat described in Embodiment 1;

[0038] Figure 2 yes Figure 1 Schematic diagram of the cross-section at point AA;

[0039] Figure 3 yes Figure 1 Schematic diagram of the cross-section at point BB;

[0040] Figure 4 yes Figure 1 Schematic diagram of the cross-section at point C;

[0041] Figure 5 yes Figure 1 Schematic diagram of the cross-section at point DD;

[0042] Figure 6 yes Figure 1 Schematic diagram of the cross-section at the middle EE;

[0043] Figure 7 This is a segmented diagram of the construction status of the arch seat described in Example 1;

[0044] Figure 8 yes Figure 7 Schematic diagram of the cross-section at point AA;

[0045] Figure 9 yes Figure 7 Schematic diagram of the cross-section at point BB;

[0046] Figure 10 This is a schematic diagram of the initial support structure;

[0047] Figure 11 This is a structural diagram of the initial support and secondary lining;

[0048] Figure 12 This is a frontal schematic diagram of the support at the opening of the excavated slope surface;

[0049] Figure 13 yes Figure 12 A partial schematic diagram of the vaulted roof;

[0050] Figure 14 This is a side view of the support for the opening at the excavated slope surface;

[0051] Figure 15 yes Figure 14 A magnified view of the area circled in the diagram.

[0052] Icons: 1. Embedded section; 2. Force transmission section; 3. Connecting section; 31. Pre-cast section; 32. Post-cast section; 4. Isolation layer; 51. Initial support of force transmission section; 52. Initial support of embedded section; 61. Secondary lining of force transmission section; 62. Secondary lining of embedded section; 6. Pre-grouting small guide pipe; 7. Hollow grouting anchor; 8. Early-strength concrete of initial support; 9. Circumferential reinforcement of initial support; 10. Longitudinal reinforcement of initial support; 11. Early-strength concrete of secondary lining; 12. Circumferential reinforcement of secondary lining; 13. Longitudinal reinforcement of secondary lining; 14. Stirrups of secondary lining; 15. Prestressed tendon; 16. Unloading strip; 17. Excavation slope; 18. Main arch; 19. Steel arch frame; 20. Concrete arch; 21. Orifice pipe; 22. Mortar-grouted rubble masonry; 23. Steel pipe. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings.

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0055] Example 1

[0056] This embodiment provides an arch base, see [link / reference] Figure 1It includes a fixed section 1, a force transmission section 2 and a connecting section 3 arranged sequentially along its length. The fixed section 1 is located within the unloading zone 16 of the slope. The force transmission section 2 is located between the unloading zone 16 and the excavated slope surface 17 of the slope. The connecting section 3 is located outside the excavated slope surface 17. The fixed section 1, the force transmission section 2 and the connecting section 3 are integrally formed reinforced concrete structures. The connecting section 3 is used to connect the arch foot of the main arch 18.

[0057] The arch base described in this scheme, such as Figure 1 As shown, the length direction of the arch seat is mainly aligned with the axis of the arch foot of the main arch 18, and is determined based on the axis of the arch foot of the main arch 18. The embedded section 1 is located within the unloading zone 16 of the slope and is anchored to the rock within the unloading zone 16, providing the main resistance of the entire arch seat with the help of the rock within the unloading zone 16. The connecting section 3 is located outside the excavated slope surface 17 and mainly connects to the arch foot, facilitating the connection between the arch foot and the arch seat and preventing the arch foot from entering between the unloading zone 16 and the excavated slope surface 17 of the slope, thereby preventing the soil between the unloading zone 16 and the excavated slope surface 17 of the slope from directly affecting the main arch 18. The force transmission section 2 is located between the unloading zone 16 and the excavated slope surface 17 of the slope, serving as a path for the embedded section 1 to provide resistance to the connecting section 3. Furthermore, when the soil between the unloading zone 16 and the excavated slope surface 17 of the slope is stable, the force transmission section 2 can also provide a certain resistance to the connecting section 3. However, this resistance is not very stable and is easily affected by changes in the soil between the unloading zone 16 and the excavated slope surface 17. Using the arch seat described in this scheme, the arch seat embedding section 1 is embedded in the stable rock layer within the unloading zone 16 according to the unloading zone 16 and the excavated slope surface 17 of the slope. After the force transmission section 2 passes through the unloading zone 16 and the excavated slope surface 17, the connecting section 3 bears the load of the main arch 18. Compared with the reinforced concrete enlarged arch seat, its cross-sectional dimensions are smaller, but its anchoring capacity is better. When the slope at the bridge site is relatively steep and there are steep slopes with poorly developed unloading cracks, its excavation range is smaller, the use risk is lower, and its applicability is higher.

[0058] In this embodiment, the cross-section of the arch seat gradually changes along the length of the arch seat, and the inner end face dimension of the embedded section 1 is larger than the outer end face dimension of the connecting section 3, such as... Figure 1 As shown. The dimensions of the inner end face of the embedded section 1 are related to the load-bearing capacity of the main arch 18, and the dimensions of the end face of the connecting section 3, which directly supports the arch foot, are also related to the load-bearing capacity of the main arch 18. The size of the end face of the embedded section 1 is determined by the loads transmitted to the end face from the main arch 18 and the arch abutment itself, mainly including axial force and bending moment. A larger load requires a larger end face size, and vice versa. The size of the end face of the connecting section 3 is determined by the loads on the arch foot of the main arch 18, mainly including axial force and bending moment. A larger load requires a larger connecting section size, and vice versa. When the cross-section of the arch abutment gradually changes along its length, with the inner end being larger and the outer end smaller, as shown... Figure 2-4 As shown, if the width of the arch abutment's cross-section gradually decreases, or the height of the arch abutment's cross-section gradually decreases, or both the height and width of the arch abutment's cross-section gradually decrease, its load-bearing capacity is better than that of a uniform cross-section. Simultaneously, the force transmission section 2 can be made smaller, thus reducing the impact on the arch abutment when the soil between the unloading zone 16 and the excavated slope surface 17 of the slope is unstable. Of course, the cross-section of the arch abutment can also be uniform, which is more convenient to construct than a gradually changing cross-section. Figure 2-6 As shown, the height of the cross-section of the arch seat gradually changes along the length of the arch seat, which facilitates construction, reduces the longitudinal excavation size of the slope, and reduces risks.

[0059] In this embodiment, as Figure 1 , Figure 3 and Figure 4 As shown, an isolation layer 4 can also be provided on the outer side of the force transmission section 2. The isolation layer 4 can deform along with the deformation of the rock mass between the unloading zone 16 and the excavation slope surface 17. When the rock mass between the unloading zone 16 and the excavation slope surface 17 deforms, the deformation of the isolation layer 4 can prevent it from affecting the force transmission section 2. That is, the isolation layer 4 isolates the force transmission section 2 and the unloading zone 16 from the rock mass between the excavation slope surface 17, preventing them from interfering with each other. This avoids the rock mass deformation directly affecting the rigid stress of the arch seat, which can significantly reduce the amount of excavation on the arch seat slope and make the arch seat bear reasonable stress, reducing the impact of the rock mass between the unloading zone 16 and the excavation slope surface 17 on the arch seat. In this embodiment, the isolation layer 4 can be made of rigid polyurethane foam or other materials that meet similar elastic modulus requirements. Furthermore, the elastic modulus of the isolation layer 4 is suitable to be 1%-10% of the elastic modulus of the concrete in the force transmission section 2. The elastic modulus is less than that of the concrete material by an order of magnitude (equivalent to a softer material wrapping). When subjected to radial deformation, it can deform earlier and more easily than the concrete in the force transmission section 2, thereby preventing the concrete in the force transmission section 2 from deforming due to the force of the surrounding slope body other than the unloading zone 16.

[0060] In this embodiment, as Figure 2-6 As shown, the top of the cross-section of the arch seat is an upward-arching arc shape, and the bottom is square, which can provide support for the top of the arch seat and make excavation and pouring construction safer.

[0061] Because the anchor block arch seat is adapted to the oblique arrangement of the arch foot, prestressing is applied at the top to avoid the stress that the connecting section 3 will experience under its own weight during construction, resulting in tension at the upper end and compression at the lower end. In this embodiment, as shown... Figure 7 As shown, the top of the arch seat is also suitable to be provided with prestressed tendons 15 along its length, so that the connecting section 3 is always under pressure.

[0062] Example 2

[0063] This embodiment provides a construction method for an arch base, see [link to relevant documentation]. Figure 7 The arch base, as described in Example 1, is constructed using the following steps:

[0064] S1. A construction platform is formed by excavating the slope at the location of the arch abutment; in this plan, if... Figure 7 As shown, the arch abutment is inclined relative to the slope and is not horizontal. To facilitate construction, the slope excavation is used to form a construction platform. Unlike existing reinforced concrete arch abutment construction, it does not require the excavation of a large slope. When the slope is relatively steep and there are poor geological conditions such as unloading cracks, it can avoid slope instability and make construction safer. At the same time, the excavation of the construction platform provides a better construction site for the subsequent excavation of the pouring space, reducing the difficulty of the subsequent excavation of the pouring space and the pouring of the arch abutment.

[0065] S2. Based on the construction platform, along the length of the arch seat at the arch seat location, excavate the slope corresponding to the force transmission section 2 inward from the excavation slope surface 17 and support it to form the pouring space for the force transmission section 2. Then, excavate the slope corresponding to the embedment section 1 and support it to form the pouring space for the embedment section 1. Since the connecting section 3 of the arch seat is located outside the excavation slope surface 17, the pouring space for the force transmission section 2 and the embedment section 1 is excavated inward along the slope surface. The excavation and support method ensures the safety of excavation and subsequent pouring. The support is upward-facing and can serve as part of the arch seat after pouring, strengthening it. Before excavating the pouring space, the opening at the location corresponding to the arch seat on the excavation slope surface 17 can be supported first, such as... Figure 12-15 As shown, the opening support includes masonry rubble masonry 22 located on both sides of the opening for support. The masonry rubble masonry 22 on both sides supports an arch-shaped steel arch frame 19 and a concrete arch 20. The steel arch frame 19 is located inside the concrete arch 20. Furthermore, on the side of the top arc-shaped section of the concrete arch 20 closest to the steel arch frame 19, several orifice pipes 21 perpendicular to the concrete arch 20 are provided, and all orifice pipes 21 are spaced apart along the top arc-shaped section of the concrete arch 20. Figure 14 The inner end of the orifice pipe 21 is connected to a steel pipe 23. In addition, the inner side of the steel arch frame 19 is equipped with the initial support 51 for the force transmission section 2 and the secondary lining 61 for the force transmission section. Specifically, during the arch abutment excavation, a pipe roof pre-support consisting of steel pipe 23, I-beam steel arch frame 19, and cement mortar is installed at the opening, with a length of 10-15 meters. C30 concrete arch support is poured at the opening as a concrete arch 20. After excavation to 1 meter from the opening, the initial support consists of four parts: First, such as... Figure 8 and Figure 9As shown, pre-grouting small guide pipes 6 are inserted, arranged circumferentially at 50 cm intervals, forming an angle of 10°-12° with the excavated structural surface, with an overlap length of 1.5m; secondly, hollow grouting anchor rods 7 are inserted radially along the cross-section of the anchor plug, with different spacing in the longitudinal direction for the force transmission section 2 and the embedment section 1; thirdly, after spraying 25 mm thick early-strength concrete 8 for initial support, an I-beam steel frame is erected, followed by the laying of two layers of steel mesh; finally, the remaining thickness of early-strength concrete 8 for initial support is sprayed. Figure 10 As shown, the initial support includes early-strength concrete (8), circumferential reinforcement (9), and longitudinal reinforcement (10). After the initial support is completed, formwork is erected, reinforcement is installed, and concrete is poured for secondary lining. Figure 11 As shown, the secondary lining includes secondary lining early strength concrete 11, secondary lining circumferential reinforcement 12, secondary lining longitudinal reinforcement 13, and secondary lining stirrups 14.

[0066] S3, Reinforcing steel bars for arch abutments;

[0067] S4. Concrete for the force transmission section 2 and the embedment section 1 is poured in layers from the inside out. When the poured concrete reaches the excavation slope 17, the formwork for the corresponding connecting section 3 is erected, and then the connecting section 3 is poured, completing the arch abutment pouring. After the reinforcement of the arch abutment is laid, concrete is poured in layers from the inside out to ensure the pouring density and improve the quality of the arch abutment pouring. Because the pouring space of the force transmission section 2 and the embedment section 1 is supported, the surrounding rock mass of the pouring space can be used as the pouring formwork to directly complete the pouring of the force transmission section 2 and the embedment section 1. However, the connecting section 3 is located outside the excavation slope 17, so the formwork for the connecting section 3 needs to be erected first, and then the connecting section 3 is poured, completing the arch abutment pouring.

[0068] The construction method of the arch abutment described in this scheme has a small amount of excavation required to form the construction platform in the early stage of slope excavation. Furthermore, the pouring space for the force transmission section 2 and the embedding section 1 is constructed by excavating tunnels, with simultaneous excavation and support. This ensures that even on steep slopes with poorly developed unloading cracks, slope instability can be avoided, making construction safer. Moreover, the surrounding slope of the pouring space is used as a template for pouring the embedding section 1 and the force transmission section 2, allowing the poured embedding section 1 to be directly embedded within the unloading zone 16 of the original slope, resulting in better load-bearing capacity of the entire arch abutment.

[0069] In this embodiment, when the outer side of the force transmission section 2 of the arch seat has an isolation layer 4, in step S2, when excavating the slope and supporting it to form the pouring space of the force transmission section 2, it is also necessary to excavate the filling space of the isolation layer 4 radially outward; and after excavating the slope corresponding to the embedded section 1 and supporting it to form the pouring space of the embedded section 1, it is also necessary to fill the filling space; that is, when excavating the slope and supporting it to form the pouring space of the force transmission section 2, the isolation layer 4 is excavated at the same time to facilitate the setting of the support, and after excavating the slope corresponding to the embedded section 1 and supporting it to form the pouring space of the embedded section 1, the filling space is filled first, so that the isolation layer 4 formed by filling can serve as the pouring template of the force transmission section 2, and can be completely separated from the surrounding slope of the pouring space of the force transmission section 2 during the pouring of the force transmission section 2, avoiding contact, thereby avoiding the surrounding slope of the pouring space of the force transmission section 2 from affecting the force transmission section 2, and thus avoiding adverse effects on the bearing capacity of the arch seat.

[0070] In this embodiment, when the top of the arch seat has prestressed tendons 15, in step S3, prestressed tendons 15 along the length direction of the top of the arch seat also need to be pre-embedded; specifically, the reinforcing steel of the arch seat is installed, prestressed tendon corrugated pipes and prestressed tendons 15 are pre-embedded, and cooling water pipes are buried. In step S4, the connecting section 3 is divided into a pre-cast section 31 and a post-cast section 32 for pouring. When the poured concrete reaches the excavation slope 17, the formwork of the pre-cast section 31 is erected and the pre-cast section 31 is poured. When the strength of the poured concrete reaches 80% of the design strength, the prestressed tendons 15 are tensioned at one end of the pre-cast section 31, and then the formwork of the post-cast section 32 is erected and the post-cast section 32 is poured. By dividing the connecting section 3 into a pre-cast section 31 and a post-cast section 32 for pouring, the prestressing tendons 15 can be pre-tensioned after the pre-cast section 31 is completed, putting the connecting section 3 under compression in advance. This ensures that the prestressing tendons 15 are located inside the arch abutment when the post-cast section 32 is poured. Furthermore, if the arch foot hinge structure needs to be sealed with concrete before the main arch 18 is closed, the pre-cast section 31 and post-cast section 32 allow for the pre-embedded components such as the arch foot hinge structure to be embedded within the arch abutment.

[0071] By adopting the above construction method, the risk of stress on the surrounding rock mass during the construction of the arch seat is reduced, the construction efficiency of the arch seat is improved, and the goal of ensuring the structural safety of the arch seat foundation of the arch bridge in mountainous areas under complex and adverse geological conditions is achieved.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An arch base, characterized in that, It includes a fixed section (1), a force transmission section (2) and a connecting section (3) arranged sequentially along its length. The fixed section (1) is located inside the unloading zone (16) of the slope. The force transmission section (2) is located between the unloading zone (16) and the excavated slope surface (17) of the slope. The connecting section (3) is located outside the excavated slope surface (17). The fixed section (1), the force transmission section (2) and the connecting section (3) are integrally formed reinforced concrete structures. The connecting section (3) is used to connect the arch foot of the main arch (18). An isolation layer (4) is provided on the outside of the force transmission section (2), and the isolation layer (4) can deform with the deformation of the rock mass between the unloading zone (16) and the excavation slope (17).

2. The arch seat according to claim 1, characterized in that, The cross-section of the arch gradually changes along the length of the arch, and the inner end face dimension of the embedded section (1) is larger than the outer end face dimension of the connecting section (3). Alternatively, the cross-sections of the arches are equal.

3. The arch seat according to claim 2, characterized in that, The height of the cross-section of the arch gradually changes along the length of the arch.

4. The arch seat according to claim 1, characterized in that, The isolation layer (4) is a rigid polyurethane foam layer.

5. The arch seat according to claim 1, characterized in that, The elastic modulus of the isolation layer (4) is 1%-10% of the elastic modulus of the concrete in the force transmission section (2).

6. The arch seat according to any one of claims 1-3, characterized in that, The cross-section of the arch seat has an upward-arching circular arc at the top and a square bottom.

7. The arch seat according to any one of claims 1-3, characterized in that, The top of the arch is provided with prestressed tendons (15) along its length.

8. A construction method for an arch seat, characterized in that, The arch base includes any one of the arch bases described in claims 1-7, and the construction of the arch base includes the following construction steps: S1. Excavate the slope at the location of the arch seat to form a construction platform; S2. Based on the construction platform, along the length of the arch seat, excavate the slope of the corresponding force transmission section (2) from the excavation slope surface (17) inward and support it to form the pouring space of the force transmission section (2). Then, excavate the slope of the corresponding embedded section (1) and support it to form the pouring space of the embedded section (1). In step S2, when excavating the slope and supporting it to form the pouring space of the force transmission section (2), the filling space of the isolation layer (4) is excavated radially outward. After excavating the slope of the corresponding embedded section (1) and supporting it to form the pouring space of the embedded section (1), the filling space is filled. S3, Reinforcing steel bars for arch abutments; S4. Pour concrete for the embedded section (1) and the force transmission section (2) from the inside out. When the concrete reaches the excavation slope (17), set up the formwork for the corresponding connecting section (3) and then pour the connecting section (3). The arch seat is then completed.

9. The construction method for the arch seat according to claim 8, characterized in that, In step S3, prestressing tendons (15) along the length of the top of the arch seat also need to be pre-embedded; In step S4, the connecting section (3) is divided into a pre-cast section (31) and a post-cast section (32) for pouring. When the poured concrete reaches the excavation slope (17), the formwork of the pre-cast section (31) is erected and the pre-cast section (31) is poured. When the strength of the poured concrete reaches 80% of the design strength, the prestressing tendons (15) are tensioned at one end of the pre-cast section (31), and then the formwork of the post-cast section (32) is erected and the post-cast section (32) is poured.

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