A suspension bridge anchor and construction method thereof

Abstract

The present invention discloses a suspension bridge anchor and a construction method thereof, and relates to the technical field of suspension bridge anchor design and construction. The device comprises an inclined guide tunnel, a first anchor chamber and a second anchor chamber, the length of the guide tunnel is configured so that the thickness of the rock layer on one side below its terminal is not less than a predetermined thickness, the first anchor chamber is arranged below the guide tunnel and communicated with the terminal of the guide tunnel, a steering member is arranged in the first anchor chamber, and the steering member is located at the rock layer with a thickness not less than a predetermined thickness, the second anchor chamber is arranged vertically below the first anchor chamber and communicated with the first anchor chamber, the second anchor chamber is filled with an anchor block, and a fixing assembly is buried in the anchor block. The present invention provides a suspension bridge anchor and a construction method thereof, which combines the structural advantages of tunnel anchors and gravity anchors, and is suitable for steep slopes and areas with broken rock masses.

Description

Technical Field

[0001] The invention relates to the technical field of suspension bridge anchorage design and construction, and in particular to a suspension bridge anchorage and a construction method thereof. Background Art

[0002] Suspension bridges are becoming the preferred type of super-long span bridges due to their excellent spanning capacity. They are ideal bridges for crossing canyons, rivers and straits. They have a very broad application prospect in the mountainous western region of my country. A suspension bridge is a flexible structure, which mainly includes four parts: main beam, tower pier, cable and anchor. Among them, the anchor is the main load-bearing structure of the suspension bridge and the key part of anchoring the main cable of the suspension bridge. Its main function is to transfer the tension of the main cable to the foundation. Generally, the anchor of the suspension bridge is divided into two types: self-anchored and ground-anchored. The ground-anchored type can be divided into gravity anchor and tunnel anchor.

[0003] Tunnel anchors can better combine the engineering geological conditions of the anchor site area, and use the joint action of the anchor plug and the surrounding rock mass. The engineering scale of tunnel anchors is generally much smaller than that of gravity anchors with the same bearing capacity. It is a small-volume anchor structure that avoids large-scale excavation, saves investment, and has little impact on the surrounding environment. However, the existing tunnel anchors are generally only suitable for setting in hard rock mass with good surrounding rock conditions, and a few are located in soft rock. The rock mass where these tunnel anchors are located has good integrity and can fully utilize the huge pull-out resistance provided by the "clamping effect" of the surrounding rock. When the rock mass joint structure is developed and belongs to broken rock or even clastic rock, the surrounding rock is difficult to provide an effective "clamping effect" for the anchor plug; the dark excavation construction of large-area, large-angle, and variable-section anchor chambers is extremely difficult, construction safety is difficult to ensure, and the construction efficiency is extremely low. Therefore, tunnel anchors are not suitable for this situation.

[0004] Gravity anchors use friction to balance the horizontal component of the main cable tension. Therefore, they are huge in size. On land, they are generally constructed using methods such as slope reduction, vertical enclosure, and caisson, which require a large construction site. When the bridge site is in a mountainous area with a steep ground slope, it is necessary to excavate the mountain on a large scale and set up high slope protection. In this case, the project is difficult, damages the environment, and is difficult to implement. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a suspension bridge anchor and a construction method thereof, which combines the structural advantages of tunnel anchors and gravity anchors and is suitable for steep slopes and areas with broken rock.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A pilot tunnel arranged obliquely, wherein the length of the pilot tunnel is configured such that the thickness of the rock formation on one side below the terminal end thereof is not less than a predetermined thickness;

[0008] a first anchor chamber, which is disposed below the pilot tunnel and communicated with a terminal end of the pilot tunnel, wherein a steering member is disposed in the first anchor chamber, and the steering member is located at the rock layer having a thickness not less than a predetermined thickness;

[0009] The second anchor chamber is vertically arranged below the first anchor chamber and communicated with the first anchor chamber. Anchor blocks are filled in the second anchor chamber, and fixing components are buried in the anchor blocks.

[0010] On the basis of the above technical solution, the suspension bridge anchor also includes a main cable, one end of the main cable is used to be fixed on the suspension bridge, and the other end passes through the guide hole and the first anchor chamber in sequence, and is turned by the steering member when passing through the first anchor chamber, and after turning, it is dispersed into a plurality of steel strands arranged in parallel at intervals, and the ends of the plurality of steel strands away from the steering member are respectively connected to the fixing components in sequence.

[0011] Based on the above technical solution, the fixing assembly includes a plurality of anchors arranged at intervals, each of the anchors is connected to a corresponding one of the steel strands, and the plurality of anchors are arranged side by side along a predetermined direction so that the length variation range between the plurality of steel strands is as small as possible.

[0012] Based on the above technical solution, the angle between the plurality of steel strands and the horizontal direction varies in the range of 60° to 90°.

[0013] Based on the above technical solution, the top of the anchor block is parallel to the predetermined direction.

[0014] Based on the above technical solution, the cross section of the first anchor chamber is a circular or rounded rectangular structure with a constant or variable cross section, and the cross section of the second anchor chamber is a circular or rounded rectangular structure with a constant cross section.

[0015] On the basis of the above technical solution, the guide tunnel, the first anchor chamber and the second anchor chamber all include primary linings, and the guide tunnel and the first anchor chamber also include secondary linings attached to the inner walls of their respective primary linings, wherein the thickness of the secondary lining of the first anchor chamber is greater than the thickness of the secondary lining of the guide tunnel.

[0016] On the other hand, the present invention also provides a construction method for anchoring a suspension bridge, which combines the structural advantages of tunnel anchors and gravity anchors and is suitable for areas with steep slopes and broken rock masses.

[0017] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0018] Excavating a pilot tunnel along an inclined direction on the rock stratum, and stopping excavating the pilot tunnel when it is detected that the thickness of the rock stratum on one side below the terminal of the pilot tunnel is not less than a predetermined thickness;

[0019] Excavating a first anchor chamber below the terminal end of the pilot tunnel, arranging a steering member in the first anchor chamber, and arranging the steering member at the rock layer having a thickness not less than a predetermined thickness;

[0020] A second anchor chamber is vertically excavated below the first anchor chamber, a fixing assembly is arranged in the second anchor chamber, concrete is poured into the second anchor chamber to form an anchor block, and the fixing assembly is buried in the anchor block.

[0021] On the basis of the above technical solution, the pilot tunnel is excavated by a mining method, and the first anchor chamber and the second anchor chamber are excavated by a shaft method.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] The present invention provides a suspension bridge anchorage, which comprises an inclined guide tunnel, a vertically arranged second anchor chamber and a first anchor chamber connecting the guide tunnel and the second anchor chamber, wherein the length of the guide tunnel is determined according to the thickness of the rock layer on one side below its terminal, and when it is detected that the rock layer on one side below its terminal reaches a predetermined thickness, excavation is stopped, and a steering member in the first anchor chamber is located at a rock layer with a thickness not less than the predetermined thickness. Since the second anchor chamber is vertically arranged, the steering member needs to be used for steering the main cable. When steering, a large horizontal force is generated at the steering member. At this time, sufficient rock layer thickness at the steering member can balance the horizontal force and ensure the stability of the overall structure. In addition, the vertically arranged second anchor chamber is conducive to construction excavation. Compared with the inclined excavation method, the vertical arrangement is conducive to slag discharge, thereby accelerating construction efficiency. Among them, the vertically arranged second anchor chamber is also conducive to the anchor block located therein to fully exert its gravity effect, and use its weight to balance the tension of the main cable, thereby fixing the main cable, providing corresponding tension for the bridge, and ensuring the stability of the overall structure. The volume of the anchor block of the anchor of this suspension bridge is also smaller than that of the gravity anchor, reducing the scale of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of a suspension bridge anchorage in an embodiment of the present invention;

[0025] Figure 2 is a cross-sectional view of a pilot tunnel of a suspension bridge anchorage in an embodiment of the present invention;

[0026] Figure 3 is a vertical cross-sectional view of a first anchor chamber of a suspension bridge anchorage in an embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the suspension bridge anchorage in the embodiment of the present invention when in use.

[0028] In the figure: 1-guide tunnel, 2-first anchor chamber, 20-steering member, 21-steering member foundation, 3-second anchor chamber, 30-anchor block, 31-fixing assembly, 4-primary lining, 40-anchor rod, 41-steel frame, 42-concrete layer, 5-secondary lining, 6-main cable, 60-steel strand. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1 and Figure 4 As shown, an embodiment of the present invention provides a suspension bridge anchorage, comprising an inclined guide tunnel 1, a first anchor chamber 2, and a second anchor chamber 3, wherein the length of the guide tunnel 1 is configured such that the thickness of the rock layer on one side below the terminal thereof is not less than a predetermined thickness, the first anchor chamber 2 is arranged below the guide tunnel 1 and communicated with the terminal of the guide tunnel 1, a steering member 20 is arranged in the first anchor chamber 2, and the steering member 20 is located at a rock layer having a thickness not less than a predetermined thickness, the second anchor chamber 3 is vertically arranged below the first anchor chamber 2 and communicated with the first anchor chamber 2, an anchor block 30 is filled in the second anchor chamber 3, and a fixing assembly 31 is buried in the anchor block 30. The suspension bridge anchorage also includes a main cable 6, one end of which is used to be fixed on the suspension bridge, and the other end of which passes through the guide tunnel 1 and the first anchor chamber 2 in sequence, and is turned by the turning member 20 when passing through the first anchor chamber 2, and after turning, it is dispersed into a plurality of steel strands 60 arranged side by side at intervals, and the ends of the plurality of steel strands 60 away from the turning member 20 are respectively connected to the fixing assembly 31 in sequence.

[0031] Specifically, the anchor of the suspension bridge is generally located in the rock layer of the mountain, and the specific location is determined according to the actual location of the suspension bridge. When the guide tunnel 1 is excavated, the length of the guide tunnel 1 itself is determined according to the thickness of the rock layer on the side below the terminal. When the thickness of the rock layer on the side below the terminal can reach the predetermined thickness, the length of the guide tunnel 1 can be determined. Since the cross-sectional size of the guide tunnel is small, increasing the length of the guide tunnel will not increase the overall project scale much, and the construction difficulty is small. The first anchor chamber 2 is excavated below the guide tunnel 1, and a steering member 20 is set in the first anchor chamber 2. Since the steering member 20 will be used for the steering of the main cable 6, we know that the main cable 6 will generally bear a large tensile force. Therefore, when turning through the steering member 20, the steering member 20 will bear a large horizontal force applied to the direction of the rock layer behind it. If the thickness of the rock layer behind the steering member 20 is thin, the rock layer may be broken or crushed. The suspension bridge loses its tension and support force, which will bring great safety hazards to the bridge body itself. Here, the thickness of the rock layer behind the steering member 20 is guaranteed, thereby also ensuring the stability and safety of the bridge structure.

[0032] We know that the anchor chamber of the tunnel anchor is set at an angle. The main reason is that the areas where it is used are all areas with hard rock layers and stable geological conditions. Therefore, its principle is to use the clamping effect between rock layers to provide pull-out resistance. In areas with broken rock layers, tunnel anchors are not applicable. This anchor is equipped with a vertically set second anchor chamber 3. The vertically set second anchor chamber 3 can maximize the gravity effect of the anchor block 30 located inside it, and use the weight of the anchor block to balance the tension of the main cable, so that it can better fix one end of the main cable 6. It does not need to rely on the rock layer to provide excessive pull-out resistance. Therefore, when it is used in broken strata, it can also ensure the stability and safety of the bridge structure. In addition, since the second anchor chamber 3 is vertically arranged, the main cable 6 needs to change its direction corresponding to the direction of the second anchor chamber 3. Therefore, a steering member 20 needs to be arranged in the first anchor chamber 2. At the same time, the rock layer thickness at the steering member 20 is required to reach a predetermined required thickness to meet its bearing requirements in turn. In addition, due to the vertical arrangement, the anchor block 30 can give full play to the gravity effect, reduce the volume of the anchor body, thereby reducing the scale and difficulty of the project, and vertical excavation is much less difficult than inclined excavation.

[0033] See also Figure 1 As shown, the fixing assembly 31 includes a plurality of anchors arranged at intervals, each anchor is connected to a corresponding one of the steel strands 60, and the plurality of anchors are arranged side by side along a predetermined direction so that the length variation range between the plurality of steel strands 60 is as small as possible, thereby ensuring that the force between each steel strand 60 is equal. In addition, the top of the anchor block 30 is parallel to the predetermined direction, so that the length variation range of the entire steel strand 60 and the steel strand 60 exposed outside the anchor block 30 is as small as possible, which is conducive to the stability of the overall structure. The angle variation range between the plurality of steel strands 60 and the horizontal direction is 60° to 90°.

[0034] Furthermore, the cross section of the first anchor chamber 2 is a circular or rounded rectangular structure with equal or variable cross sections, and the cross section of the second anchor chamber 3 is a circular or rounded rectangular structure with equal cross sections. Since the first anchor chamber 2 and the second anchor chamber 3 are both relatively large in volume, the circular or rounded rectangular structure with equal cross sections can better withstand the force, and can better resist the surrounding rock pressure during the construction stage, making the initial support and the secondary lining structure safe and stable. In addition, the first anchor chamber 2 and the second anchor chamber 3 are both constructed using the shaft method, and the vertical downward construction method reduces the construction difficulty in the broken rock layer and improves the construction efficiency.

[0035] See also Figure 2-Figure 3As shown, the pilot tunnel 1, the first anchor chamber 2 and the second anchor chamber 3 all include primary lining 4, and the pilot tunnel 1 and the first anchor chamber 2 also include secondary lining 5 attached to the inner wall of each primary lining 4, wherein the thickness of the secondary lining 5 of the first anchor chamber 2 is greater than the thickness of the secondary lining 5 of the pilot tunnel 1. Specifically, the primary lining 4 includes a plurality of anchor rods 40 arranged side by side at intervals, a steel frame 41 and a concrete layer 42, the anchor rods 40 are embedded in the corresponding rock formation, the steel frame 41 is connected to the anchor rods 40, and the concrete layer 42 is laid on the side of the steel frame 41 away from the anchor rods 40.

[0036] The anchorage of the suspension bridge combines the structural advantages of tunnel anchors and gravity anchors, adopts an extended guide tunnel 1 and a vertically arranged second anchor chamber 3, fixes the main cable 6 by an anchor block 30 located at the bottom of the second anchor chamber 3, and controls the length of the guide tunnel 1 to ensure that the rock layer thickness at the turning member 20 is not less than a predetermined thickness. The anchorage overcomes the limitation that tunnel anchors can only be used in areas with good geological conditions, and also overcomes the characteristics of huge gravity anchors and difficult construction processes. The anchorage of the suspension bridge can be used on steep slopes and areas with broken rocks, and has a stable structure, good force, a relatively simple construction process, and high construction efficiency.

[0037] The present invention also provides a construction method for anchoring a suspension bridge, the steps specifically include first excavating a pilot tunnel 1 along an inclined direction on a mountain rock layer, and stopping the excavation of the pilot tunnel 1 when the thickness of the rock layer on one side below the terminal of the pilot tunnel 1 is detected to be not less than a predetermined thickness; then excavating a first anchor chamber 2 below the terminal of the pilot tunnel 1, and setting a steering member 20 in the first anchor chamber 2, and setting the steering member 20 at a rock layer with a thickness not less than a predetermined thickness; finally, vertically excavating a second anchor chamber 3 below the first anchor chamber 2, and setting a fixing assembly 31 in the second anchor chamber 3, and then pouring concrete into the second anchor chamber 3 to form an anchor block 30, and burying the fixing assembly 31 in the anchor block 30. After the anchoring of the suspension bridge is basically formed, one end of the main cable 6 is dispersed to form a plurality of steel strands 60, and the steel strands 60 are sequentially connected to the fixing assembly 31 side by side, and the other end is fixed on the suspension bridge, so as to provide tension for the bridge body, and the plurality of steel strands 60 converge at the steering member 20 and realize steering.

[0038] Specifically, during construction, the location of the guide tunnel 1 needs to be determined based on the actual location of the suspension bridge, and the guide tunnel 1 is excavated using the mining method. In the process of excavating the guide tunnel 1, it is necessary to carry out advance pre-reinforcement according to the surrounding rock conditions, such as advance small pipe pre-support or advance tunnel perimeter curtain grouting, and timely implement initial support structures such as anchor rods 40, steel frames 41 and concrete layers 42. Subsequently, the first anchor chamber 2 and the second anchor chamber 3 are excavated vertically and layered in sequence using the shaft method. Similarly, advance pre-reinforcement is carried out according to the surrounding rock conditions. Since the first anchor chamber 2 and the second anchor chamber 3 both have a certain height, a layered excavation method is adopted during the construction process, that is, the first anchor chamber 2 and the second anchor chamber 3 are divided into several layers according to the actual situation. Each time a layer is excavated, initial support structures such as anchor rods 40, steel frames 41 and concrete layers 42 are implemented. The initial lining 4 can meet the spatial stability of the first anchor chamber 2 and the second anchor chamber 3 and prevent structural deformation. During the entire excavation process, whether to use radial grouting to waterproof and reinforce the surrounding rock will be decided based on the development of groundwater to ensure the smooth progress and safety of the entire construction process.

[0039] Furthermore, since the anchor block 30 is mainly composed of concrete and has a large volume, in order to ensure its structural rigidity, the anchor block 30 also includes anchor block steel bars buried in the concrete. Before pouring concrete into the second anchor chamber 3, anchor block steel bars are first set in the second anchor chamber 3. The anchor block steel bars are generally mesh-shaped and tied together by connectors. In addition, main cable positioning brackets, rear anchor beams, anchor rods 40, cooling pipes and other components are also arranged. The main cable positioning bracket is used to assist in fixing the steel strand 60 to the anchor. After the various components are set, the anchor block concrete is poured in layers to complete the reinforced concrete structure construction of the anchor block 30.

[0040] After completing the above steps, the secondary lining 5 in the pilot hole 1 and the first anchor chamber 2 is constructed. The secondary lining 5 is composed of concrete and steel bars embedded therein. Then, the steering member foundation 21 is constructed, and the steering member 20 is installed. Finally, the main cable 6 is erected according to the actual situation, and the installation of related auxiliary projects is completed.

[0041] This construction method makes full use of the weight of the anchor block 30 to balance the tension of the main cable 6, overcomes the problem that most anchoring is difficult to implement in broken rock areas with poor geological conditions, and greatly reduces the difficulty of construction. It is suitable for situations where tunnel anchors or large-scale excavation gravity anchors cannot be used in mountainous areas. Compared with gravity anchors, it reduces mountain excavation, is beneficial to environmental protection, and reduces project costs.

[0042] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to the present invention are within the scope of protection.

Claims

1. A suspension bridge anchorage, which is arranged in a mountain rock layer, characterized in that: It includes: A guide tunnel (1) arranged obliquely, wherein the length of the guide tunnel (1) is configured so that the thickness of the rock layer on one side below the terminal end thereof is not less than a predetermined thickness; a first anchor chamber (2) disposed below the guide tunnel (1) and in communication with a terminal end of the guide tunnel (1), wherein a steering member (20) is disposed in the first anchor chamber (2), and the steering member (20) is located at a rock layer having a thickness not less than a predetermined thickness; a second anchor chamber (3) vertically arranged below the first anchor chamber (2) and in communication with the first anchor chamber (2); an anchor block (30) is filled in the second anchor chamber (3), and a fixing assembly (31) is buried in the anchor block (30); The suspension bridge anchorage further comprises a main cable (6), one end of the main cable (6) being used for fixing on the suspension bridge, and the other end of the main cable (6) passing through the guide hole (1) and the first anchor chamber (2) in sequence, and being turned by the turning member (20) when passing through the first anchor chamber (2), and after being turned, being dispersed into a plurality of steel strands (60) arranged side by side at intervals, and the ends of the plurality of steel strands (60) away from the turning member (20) are respectively connected to the fixing assembly (31) in sequence; The guide tunnel (1), the first anchor chamber (2) and the second anchor chamber (3) all include a primary lining (4), and the guide tunnel (1) and the first anchor chamber (2) also include a secondary lining (5) attached to the inner wall of each primary lining (4), wherein the thickness of the secondary lining (5) of the first anchor chamber (2) is greater than the thickness of the secondary lining (5) of the guide tunnel (1).

2. The anchorage of a suspension bridge according to claim 1, characterized in that: The fixing assembly (31) comprises a plurality of anchors arranged at intervals, each of the anchors being connected to a corresponding one of the steel strands (60), and the plurality of anchors being arranged side by side along a predetermined direction so that the length variation range between the plurality of steel strands (60) is as small as possible.

3. The suspension bridge anchorage according to claim 1, characterized in that: The angle between the plurality of steel strands (60) and the horizontal direction varies in the range of 60° to 90°.

4. The anchorage of a suspension bridge according to claim 2, characterized in that: The top of the anchor block (30) is parallel to the predetermined direction.

5. The suspension bridge anchorage according to claim 1, characterized in that: The cross section of the first anchor chamber (2) is a circular or rounded rectangular structure with a constant cross section or a variable cross section, and the cross section of the second anchor chamber (3) is a circular or rounded rectangular structure with a constant cross section.

6. A method for constructing a suspension bridge anchorage as claimed in claim 1, characterized in that: Excavating a pilot tunnel (1) along an inclined direction on a rock layer, and stopping excavating the pilot tunnel (1) when it is detected that the thickness of the rock layer on one side below the terminal end of the pilot tunnel (1) is not less than a predetermined thickness; Excavating a first anchor chamber (2) below the terminal end of the guide tunnel (1), arranging a steering member (20) in the first anchor chamber (2), and arranging the steering member (20) at a rock layer having a thickness not less than a predetermined thickness; A second anchor chamber (3) is vertically excavated below the first anchor chamber (2), a fixing assembly (31) is arranged in the second anchor chamber (3), concrete is poured into the second anchor chamber (3) to form an anchor block (30), and the fixing assembly (31) is buried in the anchor block (30).

7. The construction method according to claim 6, characterized in that: The pilot tunnel (1) is excavated using a mining method, and the first anchor chamber (2) and the second anchor chamber (3) are excavated using a shaft method.

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