A horizontal embedded anchor foundation

Abstract

The present application relates to a horizontal embedded anchor foundation, which relates to the technical field of bridge engineering, and includes an anchor body, an embedded wall, a pier, a cable-stayed beam and an anchor chamber. Since the embedded wall is arranged below the bottom surface of the anchor body and is horizontally embedded in the bedrock, it can provide a large part of the anti-sliding bearing capacity for the anchor foundation. Compared with the gravity anchor foundation, when the same anti-sliding bearing capacity is met, the required anchor body weight is smaller; in addition, a boss is arranged at the bottom of the anchor body to meet the requirements of the anchoring system for the anchoring space, which can avoid the overall downward movement of the anchor body base surface and the increase in the excavation of the foundation pit; the bottom surface of the boss is arranged above the sea level or the groundwater level line, which can avoid groundwater from infiltrating into the anchor body and affecting the durability of the main cable anchor system anchored in the anchor body boss. Therefore, the present application can not only reduce the scale of the anchor foundation, save material consumption, and reduce the amount of mountain excavation, but also ensure the durability of the main cable anchor system.

Description

Technical Field

[0001] The present application relates to the technical field of bridge engineering, and in particular to a horizontal embedded anchor foundation. Background Art

[0002] As one of the long-span bridge types, suspension bridges are often used in cross-sea bridge projects. As the main load-bearing component of suspension bridges, the selection of structural type and design of structural dimensions of anchors are often restricted by many factors, such as coastal ecological red lines, coastal topography, coastal hydrogeology, port terminals, etc.

[0003] In the related technology, under the conditions of coastal slope terrain and bedrock geology, gravity anchors or tunnel anchors are usually used as the anchor foundation of the main cable of the suspension bridge. The gravity anchor foundation resists the horizontal tension of the main cable through the friction between the base and the foundation, and the friction force is equal to the product of the anchor's deadweight after deducting the vertical component of the main cable and the friction coefficient. The friction coefficient is a constant. Therefore, in order to resist the huge main cable tension, it is necessary to greatly increase the deadweight of the anchor, so the scale of the gravity anchor foundation is often very large. In addition to the large amount of structural materials used in the huge-scale gravity anchor foundation, when it is used in coastal slope terrain, there are also problems such as large amount of mountain excavation for foundation pit construction, high cost of slope protection, and encroachment on the coastal ecological red line. Tunnel anchors resist the huge pulling force of the main cable through the cohesion and embedding effect between the anchor body and the bedrock surface. Although the foundation scale is relatively small and the amount of mountain excavation is also small, it has high requirements on the quality of the surrounding rock. Due to limited conditions, the anchor body usually needs to be set below the water level. If the surrounding rock has poor integrity and strong permeability, there will be problems such as greater difficulty and risk in anchor hole construction and poor durability of the main cable anchoring system. Summary of the invention

[0004] The embodiment of the present application provides a horizontal embedded anchor foundation to solve the problems existing in the related technology, such as large foundation scale, large material consumption, large amount of mountain excavation, construction difficulty and risk greatly affected by bedrock quality, and durability of the main cable anchoring system greatly affected by groundwater.

[0005] In a first aspect, a horizontal embedded anchor foundation is provided, comprising an anchor body, wherein the top surface of the front end of the anchor body is set as a horizontal plane, the tail portion is set as an inclined surface, the slope of the inclined surface is equal to the slope of the mountain excavation, and the bottom of the anchor body is provided with a boss, the bottom surface of the boss is higher than the sea level or the groundwater level;

[0006] An embedded wall, which is arranged at the bottom of the anchor body and below the main cable anchoring system, with its top connected to the bottom of the anchor body, and is horizontally embedded in the bedrock;

[0007] A buttress, the buttress being arranged on the top surface of the front end of the anchor body;

[0008] A cable-stayed beam, one end of which is connected to the anchor body, and the other end of which is connected to the top of the pier;

[0009] The anchor chamber is arranged on the anchor body, the pier and the cable-stayed beam, and is a hollow three-dimensional structure surrounded by a bottom plate and a shield. The rear end of the shield is connected to the anchor body, and the bottom plate is fixedly connected to the cable-stayed beam.

[0010] In some embodiments, the front end of the embedded wall is set to have a constant thickness, and the rear end is set to have a variable thickness, and its cross section is a wedge-shaped shape that is narrow at the front and wide at the back; the expansion angle of the side wall where the embedded wall varies in thickness is less than or equal to 30°.

[0011] The embedded wall is provided with lateral protrusions at equal intervals along the longitudinal direction, and its cross section is string-shaped; the expansion angle of the side wall at the lateral protrusion of the embedded wall is less than or equal to 45°.

[0012] Two embedded walls are arranged below the single main cable anchoring system.

[0013] The buttress is vertically arranged on the top surface of the front end of the anchor body.

[0014] A cable-stayed beam is provided on both sides below the bottom plate, and prestressed tendons are provided in the cable-stayed beam. The prestressed tendons are tensioned in a single-end tensioning manner, with the anchoring end being provided in the anchor body and the tensioning end being provided at the top of the pier.

[0015] The center of gravity of the anchor foundation is set at the rear side of the center line of the bottom surface of the anchor foundation, and the distance L1 between the center of gravity of the anchor foundation and the center line must satisfy the following calculation formula:

[0016] L1=(Q d +0.5Q L )×(cosθ×H-sinθ×L2) / G

[0017] Where: Q d is the total cable force of the suspension bridge under the dead load, Q L is the total cable force of the live load of the suspension bridge system, θ is the incident angle of the main cable at the cable-spreading point, H is the vertical height of the cable-spreading point from the bottom surface of the anchor foundation, L2 is the longitudinal horizontal distance from the cable-spreading point to the center line of the bottom surface of the anchor foundation, and G is the deadweight of the anchor foundation.

[0018] The calculation formula of the anti-sliding stability coefficient K of the anchor foundation is as follows:

[0019]

[0020] Where: K1 is the anti-sliding safety factor of the base friction, K2 is the anti-sliding safety factor of the embedded wall anchored in the bedrock, μ is the base friction coefficient, G is the deadweight of the anchor foundation, Q is the total cable force of the main cable of the suspension system bridge, θ is the incident angle of the main cable at the cable-spreading point, c is the cohesion of the bedrock, A 1i is the side wall area of ​​the embedded wall, α i is the expansion angle of the embedded wall side wall, and A2 is the bottom area of ​​the embedded wall.

[0021] The beneficial effects brought about by the technical solution provided in this application include: reducing the scale of the anchor foundation, saving material consumption, reducing the amount of mountain excavation, reducing construction difficulty and risk, and preventing the durability of the main cable anchoring system from being affected by groundwater.

[0022] The embodiment of the present application provides a horizontal embedded anchor foundation. Since the embedded wall is arranged below the anchor body, the foundation pit construction can be directly carried out by manual excavation or blasting into a trench after the main foundation pit of the anchor body is formed, and the construction is convenient and has low risk. The embedded wall is embedded in the bedrock, which can provide anchor anti-slip bearing capacity, and at the same time, the deadweight of the anchor body can provide base friction anti-slip bearing capacity. The two work together to effectively reduce the scale of the anchor foundation, thereby saving the material consumption of the structure itself and reducing the amount of mountain excavation. In addition, a boss is provided at the bottom of the anchor body to meet the requirements of the anchor system for the anchoring space, which can avoid the overall downward shift of the anchor body base surface and cause an increase in the foundation pit excavation volume; the bottom surface of the boss is arranged above the sea level or the groundwater level line, which can avoid groundwater from seeping into the anchor body and affecting the durability of the main cable anchoring system anchored in the anchor body boss. Therefore, compared with the gravity anchor foundation, this application reduces the scale of the anchor foundation, saves the material consumption of the structure itself, and reduces the amount of mountain excavation; compared with the tunnel anchor foundation, it reduces the construction difficulty and risk, and can ensure the durability of the main cable anchoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram of the side elevation structure of a horizontal embedded anchor foundation provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of the front elevation structure of a horizontal embedded anchor foundation provided in an embodiment of the present application;

[0026] Figure 3 A schematic diagram of a planar structure of a horizontal embedded anchor foundation provided in an embodiment of the present application;

[0027] Figure 4 A schematic diagram of the planar structure of a wedge-shaped anchor plug embedded in a wall provided in an embodiment of the present application;

[0028] Figure 5 A schematic diagram of the planar structure of a string of anchor plugs embedded in a wall provided in an embodiment of the present application.

[0029] In the figure: 1-anchor body, 11-boss, 2-embedded wall, 3-pier, 4-cable-stayed beam, 41-prestressed tendons, 5-anchor chamber, 51-bottom plate, 52-shield, 6-main cable anchoring system, 7-cable point, 8-center of gravity of anchor foundation. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] The embodiment of the present application provides a horizontal embedded anchor foundation, which can solve the problems existing in the related technology, such as large foundation scale, large material consumption, large amount of mountain excavation, construction difficulty and risk greatly affected by bedrock quality, and durability of the main cable anchoring system affected by groundwater.

[0032] See also Figure 1 to Figure 3As shown, a horizontal embedded anchor foundation provided by an embodiment of the present application comprises an anchor body 1, an embedded wall 2, a pier 3, a cable-stayed beam 4 and an anchor chamber 5. The anchor body 1 is a solid concrete structure, and the top surface of its front end is set as a horizontal plane to facilitate the construction operations of the pier 3, the anchor chamber 5 and other parts; the tail of the anchor body 1 is set as an inclined surface, and the slope of the inclined surface is consistent with the slope of the mountain excavation, which can make the tail of the anchor body 1 supported on the excavation slope surface, reduce the base stress generated by the deadweight of the anchor body 1 during the construction stage, and at the same time, make the center of gravity of the anchor foundation move backward, generate a pre-applied reverse bending moment on the base plane, so as to balance the positive bending moment generated by the main cable force on the base plane during the bridge construction stage, thereby reducing the bending moment on the stress distribution in front and rear of the base plane. The influence makes the base stress distribution more uniform; a boss 11 is provided at the bottom of the anchor body 1 to meet the requirements of the main cable anchoring system 6 for the anchoring space, which can avoid the overall downward shift of the base surface of the anchor body 1 and cause an increase in the excavation of the foundation pit; the bottom surface of the boss 1 is arranged above the sea level or the groundwater level, which can avoid groundwater from seeping into the anchor body 1 and affecting the durability of the main cable anchoring system 6 anchored in the boss 11; the number of bosses 11 arranged along the transverse direction of the bridge corresponds to the number of main cables of the suspension system bridge, that is, a boss 11 is arranged under each main cable anchoring system 6, and the size of the boss 11 is determined according to the size of the main cable anchoring system 6, ensuring that the main cable anchoring system 6 can be completely set in the concrete of the anchor body 1 and has a sufficient protective layer thickness.

[0033] The embedded wall 2 is a reinforced concrete structure, which is horizontally arranged at the bottom of the anchor body 1 along the longitudinal direction of the bridge, and is located below the anchoring range of the main cable anchoring system 6. Its top is connected to the bottom of the anchor body 1 and is horizontally embedded in the bedrock. The foundation pit construction of the embedded wall 2 can be directly carried out by artificial excavation or blasting after the main foundation pit of the anchor body is formed, which is convenient for construction and has low risk. The depth of the embedded wall 2 embedded in the bedrock is 2 to 3 times its wall thickness. The horizontal cross-sectional area of ​​the embedded wall 2 is determined according to the horizontal shear force transmitted by the anchor body 1, and the longitudinal length is determined according to the balance condition between the horizontal shear force transmitted by the anchor body 1 and the horizontal bearing capacity provided by the bedrock. In addition, the number of embedded walls 2 arranged on the bottom surface of the anchor body 1 along the transverse direction of the bridge corresponds to the number of main cable anchoring systems 6 of the suspension system bridge. Preferably, two embedded walls 2 are arranged under a single main cable anchoring system 6 to make the transmission of horizontal shear force more direct and reliable.

[0034] The pier 3 is a hollow reinforced concrete structure, which is arranged on the top surface of the front end of the anchor body 1; preferably, the pier 3 is vertically arranged on the top surface of the front end of the anchor body 1, which can effectively shorten the required length of the front end of the anchor body 1 and avoid the anchor foundation from encroaching on the marine ecological red line.

[0035] The diagonal beam 4 is arranged below the bottom plate 51 of the anchor chamber 5. It is a prestressed concrete structure, that is, a prestressed tendon 41 is arranged in the diagonal beam 4. The prestressed tendon 41 is tensioned by a single-end tensioning method. Its anchoring end is embedded in the anchor body 1, and the tensioning end is arranged at the top of the pier 3. The prestressed diagonal beam 4 is arranged between the anchor body 1 and the pier 3, so that the horizontal component of the loose cable saddle on the pier 3 can be directly transmitted to the anchor body 1, reducing the bending moment at the bottom of the pier 3, so that the pier 3 is mainly under pressure. Preferably, a diagonal beam 4 is arranged on the left and right sides below the bottom plate 51 of the anchor chamber 5, which can provide vertical support for the bottom plate 51 and the shield 52 of the anchor chamber 5.

[0036] The anchor chamber 5 is arranged on the anchor body 1, the pier 3 and the cable-stayed beam 4, and includes a hollow three-dimensional structure surrounded by a shield 52 and a bottom plate 51 fixed to the bottom of the shield 52. The rear end of the shield 52 is connected to the anchor body 1, and the bottom plate 51 is fixedly connected to the cable-stayed beam 4.

[0037] The center of gravity 8 of the entire anchor foundation is set at the rear side of the center line of the anchor foundation bottom surface in the longitudinal bridge direction, and the distance L1 between the center of gravity 8 of the anchor foundation and the center line satisfies the following formula, which ensures that the bending moment of the anchor foundation base is basically zero in the bridge completion stage, the base is compressed close to the center, the base stress is evenly distributed, and the stress peak is small; the calculation formula of L1 is as follows:

[0038] L1=(Q d +0.5Q L )×(cosθ×H-sinθ×L2) / G

[0039] Where: Q d is the total cable force of the suspension bridge under the dead load, Q L is the total cable force of the live load of the cable suspension system bridge, θ is the incident angle of the main cable at the cable point 7, H is the vertical height of the cable point 7 from the bottom surface of the anchor foundation, L2 is the longitudinal horizontal distance from the cable point 7 to the center line of the bottom surface of the anchor foundation, and G is the deadweight of the anchor foundation.

[0040] The calculation formula of the anti-sliding stability coefficient K of the entire anchor foundation is as follows:

[0041]

[0042] Where: K1 is the anti-sliding safety factor of base friction, K2 is the anti-sliding safety factor of embedded wall 2 anchored in bedrock, μ is the base friction coefficient, G is the deadweight of the anchor foundation, Q is the total cable force of the main cable of the suspension system bridge, θ is the incident angle of the main cable at the cable-spreading point 7, c is the cohesion of the bedrock, A 1i is the side wall area of ​​embedded wall 2, α i is the expansion angle of the side wall of embedded wall 2, and A2 is the bottom area of ​​embedded wall 2.

[0043] Preferably, see Figure 4 and Figure 5As shown, the front end of the embedded wall 2 is set to have a constant thickness, and the rear end is set to have a variable thickness, so as to form a wedge-shaped anchor body that is narrow at the front and wide at the back on the plane, and the side wall expansion angle α1 is less than or equal to 30°; or the embedded wall 2 is provided with lateral protrusions at equal intervals along the longitudinal direction, so as to form a string-shaped anchor body on the plane, and the side wall expansion angle α2 at the lateral protrusions is less than or equal to 45°. The embedded wall 2 is designed to be a wedge-shaped anchor body or a string-shaped anchor body, so that the anchor body 1 can be firmly combined with the bedrock, thereby greatly improving the anchoring anti-slip bearing capacity of the embedded wall 2 in the bedrock.

[0044] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0045] It should be noted that, in this application, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0046] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A horizontal embedded anchor foundation, characterized in that: include: An anchor body (1), wherein the top surface of the front end of the anchor body (1) is set as a horizontal plane, and the tail is set as an inclined surface, the slope of the inclined surface is equal to the slope of the mountain excavation, and the bottom of the anchor body (1) is provided with a boss (11), and the bottom surface of the boss (11) is higher than the sea level or the groundwater level; An embedded wall (2), the embedded wall (2) is arranged at the bottom of the anchor body (1) and below the main cable anchoring system (6), the top of the embedded wall is connected to the bottom of the anchor body (1), and the embedded wall (2) is horizontally embedded in the bedrock; A buttress (3), the buttress (3) being arranged on the top surface of the front end of the anchor body (1); A cable-stayed beam (4), one end of which is connected to the anchor body (1), and the other end of which is connected to the top of the pier (3); An anchor chamber (5), the anchor chamber (5) being arranged on the anchor body (1), the pier (3) and the cable-stayed beam (4), and being a hollow three-dimensional structure surrounded by a bottom plate (51) and a shield (52), the rear end of the shield (52) being connected to the anchor body (1), and the bottom plate (51) being fixedly connected to the cable-stayed beam (4); Wherein, two embedded walls (2) are arranged below the single main cable anchoring system (6); and the pier (3) is vertically arranged on the top surface of the front end of the anchor body (1).

2. A horizontal embedded anchor foundation as claimed in claim 1, characterized in that: The front end of the embedded wall (2) is set to have a constant thickness, and the rear end is set to have a variable thickness, and its cross section is a wedge shape that is narrow at the front and wide at the rear; the expansion angle of the side wall at the location where the embedded wall (2) has a variable thickness is less than or equal to 30°.

3. The horizontal embedded anchor foundation according to claim 1, characterized in that: The embedded wall (2) is provided with lateral protrusions at equal intervals along the longitudinal direction, and its cross section is string-shaped; the side wall expansion angle at the lateral protrusion of the embedded wall (2) is less than or equal to 45°.

4. The horizontal embedded anchor foundation according to claim 1, characterized in that: A diagonal beam (4) is provided on both sides below the bottom plate (51), and a prestressed tendon (41) is provided in the diagonal beam (4). The prestressed tendon (41) is tensioned in a single-end tensioning manner, with its anchoring end being provided in the anchor body (1) and the tensioning end being provided at the top of the pier (3).

5. The horizontal embedded anchor foundation according to claim 1, characterized in that: The anchor foundation gravity center (8) is located at the rear side of the anchor foundation bottom surface center line, and the distance L1 between the anchor foundation gravity center (8) and the center line needs to satisfy the following calculation formula: L1=(Q d +0.5Q L )×(cosθ×H-sinθ×L2) / G Where: Q d is the total cable force of the cable suspension bridge, Q L is the total cable force of the cable suspension bridge, θ is the incident angle of the main cable at the cable point (7), H is the vertical height of the cable point (7) from the bottom of the anchor foundation, L2 is the longitudinal horizontal distance from the cable point (7) to the center line of the bottom of the anchor foundation, and G is the deadweight of the anchor foundation.

6. The horizontal embedded anchor foundation according to claim 1, characterized in that: The calculation formula of the anti-sliding stability coefficient K of the anchor foundation is as follows: Where: K1 is the anti-sliding safety factor of the base friction, K2 is the anti-sliding safety factor of the embedded wall (2) anchored in the bedrock, μ is the base friction coefficient, G is the deadweight of the anchor foundation, Q is the total cable force of the main cable of the suspension system bridge, θ is the incident angle of the main cable at the cable-spreading point (7), c is the cohesion of the bedrock, A 1i is the side wall area of ​​the embedded wall (2), α i is the expansion angle of the side wall of the embedded wall (2), and A2 is the bottom area of ​​the embedded wall (2).

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