Suspension bridge composite anchorage structure and construction method

Abstract

The present application relates to a kind of suspension bridge composite anchorage structure and construction method, the structure, including anchor chamber, anchor pile and U type anchor beam, fixed cable saddle is set in the middle of U type anchor beam, and corner cable saddle is respectively set in two sides corner;Main cable is anchored in fixed cable saddle after being turned over corner cable saddle.The component force of the pull of main cable in vertical direction is balanced with the sum of the pull resistance of anchor pile, the gravity of anchor pile and the gravity of anchor body, and the component force in horizontal direction is balanced with the horizontal resistance of anchor pile and the horizontal shear of rock mass in U type anchor beam, to realize the anchoring of main cable.The anchorage mode of anchor pile, U type anchor beam and corner cable saddle uses the pull resistance and horizontal resistance of anchor pile, and fully utilizes the resistance of rock mass wrapped by U type anchor beam, under the same surrounding rock grade and anchorage bearing capacity, the present composite anchorage is less than other composite anchorage process, and the concrete consumption of traditional gravity type anchorage is small, significantly reduces the earthwork excavation amount and concrete consumption, low carbon environmental protection, reduces engineering investment, open cut construction, construction is simple, risk is small, and operation and maintenance are convenient.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and more particularly to a composite anchorage structure for suspension bridges and its construction method. Background Technology

[0002] Currently, suspension bridges mainly use two types of anchorages: gravity anchorages and composite anchorages. Composite anchorage structures mainly include tunnel anchorages and gravity or tunnel-type anchorages combined with anchor cables. Tunnel anchorages are typically built in inclined tunnels within relatively hard or intact rock masses. The tension of the main cable is transferred to the surrounding rock through the anchor plug. The earthwork excavation, concrete construction volume, and environmental impact are less than with gravity anchorages. However, for bridges with large load-bearing capacity, the amount of concrete required for the tunnel anchorage is still very large, as are the excavation and concrete pouring volumes. Existing composite anchorages have complex construction procedures, and the pull-out force of the anchor cables is difficult to coordinate. Gravity anchorages are generally used in foundations with weak surface rock masses, relying on their own weight and the friction between the foundation to resist the tension of the main cable. This involves large earthwork excavation, concrete construction, numerous procedures, high costs, and significant adverse environmental impacts. Summary of the Invention

[0003] To address the above problems, this invention provides a composite anchorage structure and construction method for suspension bridges, which fully utilizes the rock mass resistance and the pull-out force of the anchor piles. The structure is simple, requires minimal earthwork excavation (open excavation), involves a small amount of concrete, and is convenient and low-risk to construct.

[0004] The technical solution adopted in this invention is: a composite anchorage structure for suspension bridges, characterized by: an anchor chamber excavated in the rock subgrade at the bridge abutment of the suspension bridge, reinforced concrete anchor piles integrally cast adjacent to the anchor chamber, and a U-shaped anchor beam on the anchor pile. The U-shaped anchor beam encloses and embeds itself into the rock mass of the bridge abutment subgrade. A fixed saddle is set in the middle of the U-shaped anchor beam, and corner saddles are set at the two corners respectively. The main cable is anchored to the fixed saddle after turning through the corner saddles. The vertical component of the main cable tension is balanced with the sum of the anchor pile pull-out force, the anchor pile weight, and the anchor weight; the horizontal component is balanced with the anchor pile horizontal resistance and the horizontal shear force of the rock mass in the U-shaped anchor beam, thereby achieving the anchorage of the main cable.

[0005] Preferably, the U-shaped anchor beam is an enlarged reinforced concrete structure, including an enlarged structure, an upstream wing wall, and a downstream wing wall. The upstream and downstream wing walls are located on both sides of the enlarged structure, forming a U-shaped structure. Corner saddles are provided at the corners of the enlarged structure and the upstream and downstream wing walls. The fixed saddles are located in the middle of the enlarged structure.

[0006] Preferably, the side of the U-shaped anchor beam adjacent to the anchor chamber is an outwardly convex arc shape, and is slightly higher than both ends of the U-shaped anchor beam.

[0007] Preferably, when used for cable-stayed suspension, the main cable is inclined, and the bottom surface of the U-shaped anchor beam used to install the fixed cable saddle is an inclined surface perpendicular to the main cable.

[0008] Preferably, when used for horizontal suspension cables, the main cable is horizontal, and the bottom surface of the U-shaped anchor beam used to install and fix the cable saddle is vertical. The main cable trench is excavated on both sides of the rock mass in front of the U-shaped anchor beam to the main bridge through which the main cable passes. The enlarged structure of the U-shaped anchor beam can be set into a trumpet shape, and the stress-bearing side in contact with the rock mass can be set into an arc shape to further expand the bearing capacity of the rock mass.

[0009] Preferably, the top surface of the U-shaped anchor beam is at the same elevation as the top surface of the rock mass it encloses, and it also serves as the bridge abutment roadbed.

[0010] Preferably, the anchor piles and U-shaped anchor beams form a U-shape on the elevation, and the rock mass between the U-shaped anchor beams and the side end of the main bridge serves as a component of the bridgehead roadbed and the composite anchor structure.

[0011] Preferably, the number of anchor piles is 2 to 3, the U-shaped anchor beam is symmetrical about the longitudinal axis of the main beam of the bridge, and the anchor piles are truncated cone structures with a larger bottom and a smaller top, making full use of the pull-out resistance of the deep rock mass.

[0012] The present invention discloses a method for constructing a composite anchorage structure for a suspension bridge, comprising the following steps:

[0013] 1) Determine the location of the anchorage chamber of the suspension bridge according to the design drawings and construction layout. Excavate the anchorage chamber and U-shaped anchor beam groove on the rock subgrade using manual, mechanical or smooth blasting techniques. Drill anchor pile holes manually or mechanically. For the broken surrounding rock, spray anchoring and consolidation grouting are carried out.

[0014] 2) After excavation, clean the anchor pile holes, tie the reinforcing bars, install the embedded parts of the corner saddle and the fixed saddle, pour reinforced concrete anchor piles and U-shaped anchor beams in one piece, and spray anchors or pour anchor chamber support.

[0015] 3) After the concrete reaches the design age, install corner saddles at the corner sections of the U-shaped anchor beam and install fixed saddles in the middle of the crossbeam of the U-shaped anchor beam.

[0016] 4) Guide the main cable of the suspension bridge to the corner saddle and the fixed saddle, and anchor it to the fixed saddle;

[0017] 5) Ancillary facilities such as protective glass canopies for the main cable strands, angle saddles, and fixed saddles during construction protection;

[0018] 6) Anti-corrosion treatment of the main cable, installation of drainage facilities in the anchor chamber or drilling of drainage holes.

[0019] The beneficial effects of this invention are as follows: By employing an anchoring method combining anchor piles, U-shaped anchor beams, and angled cable saddles, this composite anchoring system utilizes the pull-out force and horizontal resistance of the anchor piles, and fully leverages the rock mass resistance enclosed by the U-shaped anchor beams. Under the same surrounding rock grade and anchoring bearing capacity, this composite anchoring system requires fewer procedures than other composite anchoring systems, uses less concrete than traditional gravity anchoring systems, significantly reduces earthwork excavation and concrete consumption, is low-carbon and environmentally friendly, lowers project investment, is simple to construct, has low risk, and is convenient to operate and maintain. This invention has the following advantages:

[0020] 1. Anchor chambers, anchor piles, and U-shaped anchor beams are installed on the rock foundation on the connecting side of the bridge site. The rock mass wrapped by the U-shaped anchor beams is used to replace the large concrete anchor body of the traditional gravity anchor, making full use of the rock mass resistance and the pull-out force of the anchor piles.

[0021] 2. Under the same conditions of surrounding rock grade and bearing capacity, the composite anchor pile is smaller in size than the traditional gravity anchor, which greatly reduces the amount of earthwork excavation and reinforced concrete pouring. It is also less expensive than gravity anchor and tunnel anchor, and is low-carbon and environmentally friendly.

[0022] 3. Anchoring involves fewer procedures, making open-cut construction simpler, less risky, shorter in duration, lower in cost, and easier to operate and maintain. Attached Figure Description

[0023] Figure 1 is a longitudinal section of the composite anchorage of the cable-stayed suspension bridge anchor pile and rock mass of the present invention;

[0024] Figure 2 is a plan view of the composite anchorage of the cable-stayed suspension bridge anchor pile and rock mass according to the present invention;

[0025] Figure 3 is a cross-sectional view of the composite anchorage of the cable-stayed suspension bridge anchor pile and rock mass of the present invention.

[0026] Figure 4 is a longitudinal section of the horizontal suspension bridge anchor pile and rock mass composite anchorage of the present invention.

[0027] Figure 5 is a plan view of the horizontal suspension bridge anchor pile and rock mass composite anchorage of the present invention;

[0028] Figure 6 is a cross-sectional view of the horizontal suspension bridge anchor pile and rock mass composite anchorage of the present invention.

[0029] In the diagram: 1—Bridgehead roadbed, 2—Anchor chamber, 3—Anchor pile, 3a—Upstream anchor pile, 3b—Downstream anchor pile, 3c—Intermediate anchor pile, 4—U-shaped anchor beam, 4a—Enlarged structure, 4b—Upstream wing wall, 4c—Downstream wing wall, 4d—Upstream saddle beam, 4e—Downstream saddle beam, 5—Fixed cable saddle, 6—Angle cable saddle, 6a—Upstream angle cable saddle, 6b—Upstream angle cable saddle, 7—Main cable, 7a—Upstream main cable, 7b—Downstream main cable, 7c—Upstream main cable trough, 7d—Downstream main cable trough, 8—Rock mass, 9—Facade, 9a—Upstream cable saddle facade, 9b—Downstream cable saddle facade, 10—Main bridge, 11—Cable saddle ball bearing system, 11a—Upstream cable saddle ball bearing system, 11b—Downstream cable saddle ball bearing system. Detailed Implementation

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

[0031] like Figure 1 As shown in Figure 8, a composite anchorage structure for a suspension bridge according to the present invention includes an anchor chamber 2, anchor piles 3, and a U-shaped anchor beam 4. The anchor chamber 2 is formed by mechanical or blasting excavation in the rock mass 8 of the roadbed at the bridgehead on one side of the suspension bridge. The anchor piles 3 are adjacent to the anchor chamber 2 according to design requirements. The U-shaped anchor beam 4 is set on the anchor piles 3. The U-shaped anchor beam 4 is an enlarged reinforced concrete structure. The anchor piles 3 and the U-shaped anchor beam 4 are an integral reinforced concrete structure. The fixed cable saddle 5 is installed on the U-shaped anchor beam 4 adjacent to the anchor chamber 2. The fixed cable saddle 5 and the U-shaped anchor beam 4 are on the same plane as the longitudinal axis of the main bridge. The corner of the corner where the corner cable saddle 6 is installed on the end face of the U-shaped anchor beam 4 is an arc. The side of the U-shaped anchor beam 4 adjacent to the anchor chamber 2 where the fixed cable saddle 5 is installed is slightly higher than the two ends of the U-shaped anchor beam 4 and convex outwards, gradually tapering to form an installation... The bottom surface of the fixed saddle 5, the main cable 7 of the rock excavation outside the U-shaped anchor beam 4 passes through the main cable groove (upstream main cable groove 7c and downstream main cable groove 7d), the two ends of the U-shaped anchor beam 4 are equipped with saddle beams (upstream saddle beam 4d and downstream saddle beam 4e) for installing angle saddles 6, the saddle beams are equipped with cable saddle ball bearing rows 11 (upstream cable saddle ball bearing rows 11a and downstream cable saddle ball bearing rows 11b), the contact surface between the angle saddle 6 and the arc section of the U-shaped anchor beam 4 is covered with panels 9 (upstream cable saddle panel 9a and downstream cable saddle panel 9b), the main cable 7 (upstream main cable 7a and downstream main cable 7b) is moved from the main cable groove (upstream main cable groove 7c and downstream main cable groove 7d) to both ends of the U-shaped anchor beam 4, and is turned by the angle saddle 6 to be anchored on the fixed saddle 5 in the middle of the side of the U-shaped anchor beam 4 adjacent to the anchor chamber 2.

[0032] In this embodiment, the U-shaped anchor beam 4 is an enlarged reinforced concrete structure, including an enlarged structure 4a, an upstream wing wall 4b, and a downstream wing wall 4c. The upstream wing wall 4b and the downstream wing wall 4c are located on both sides of the enlarged structure 4a, forming a U-shaped structure. Corner saddles 6 are provided at the corners of the enlarged structure 4a, the upstream wing wall 4b, and the downstream wing wall 4c. Fixed saddles 5 are located in the middle of the enlarged structure 4a.

[0033] In this embodiment, the side of the U-shaped anchor beam 4 adjacent to the anchor chamber 2 is an outwardly convex arc shape, and is slightly higher than both ends of the U-shaped anchor beam 4.

[0034] Combination Figure 1-3 As shown, in this embodiment, when used for a cable-stayed suspension, the main cable 7 is inclined, and the bottom surface of the U-shaped anchor beam 4 used to install and fix the cable saddle 5 is an inclined surface perpendicular to the main cable 7. The enlarged structure of the U-shaped anchor beam can be set into a trumpet shape, and the stress-bearing side in contact with the rock mass can be set into an arc shape to further expand the bearing capacity of the rock mass.

[0035] Combination Figure 4-6 As shown, in this embodiment, when used for horizontal suspension, the main cable 7 is horizontal, the bottom surface of the U-shaped anchor beam 4 used to install and fix the cable saddle 5 is vertical, and the main cable groove through which the main cable 7 passes is excavated on both sides of the rock mass in front of the U-shaped anchor beam 4 to the main bridge 10.

[0036] In this embodiment, the top surface of the U-shaped anchor beam 4 and the top surface of the rock mass 8 it encloses are at the same elevation, and it also serves as the roadbed of the bridge abutment roadbed.

[0037] In this embodiment, the anchor pile 3 and the U-shaped anchor beam 4 form a U-shape on the elevation. The rock mass 8 between the U-shaped anchor beam 4 and the side end of the main bridge 10 also serves as a component of the bridgehead roadbed 1 and the composite anchor structure.

[0038] In this embodiment, there are 2 to 3 anchor piles 3, the U-shaped anchor beam 4 is symmetrical about the longitudinal axis of the main beam of the bridge, and the anchor pile 3 is a frustum structure with a larger bottom and a smaller top, making full use of the pull-out resistance of the deep rock mass.

[0039] The invention will now be illustrated with specific engineering examples:

[0040] The geological conditions and physical and mechanical parameters of the rock mass and concrete for this project are as follows: The rock mass is schist with a layered structure, weakly to strongly weathered, with good rock mass integrity, underdeveloped groundwater, and no controlling unfavorable structural planes. The engineering quality level of the rock mass is Class IV. The rock mass physical and mechanical parameters are: rock mass weight γ = 2.43 g / cm³. 3 saturated uniaxial compressive strength R c =15~30MPa, rock mass deformation modulus E o =5~10GPα, Poisson's ratio μ=0.27, rock mass allowable bearing capacity [ƒ α=1.00~2.50MPa; rock mass shear strength ƒ'=0.65, c=0.50MPa, shear strength ƒ=0.45; rock mass and concrete shear strength ƒˊ=0.62, c=0.48MPa, shear strength ƒ=0.42, pile skin friction ƒˊ=0.62. Single main cable tension 3.2×10 5 kN, 236 main cable strands, strand PPWS5.5-127-1860-ZnAL, cup plate CP type anchorage; concrete design grade C40.

[0041] Anchorage structure and dimensions: The main bridge is 18m wide; the anchorage chamber is 24m wide and 8m deep; there are two cylindrical anchor piles, with an upper base of 3m, a lower base of 3.2m, and a depth of 20m; the U-shaped anchor beam is an enlarged reinforced concrete structure, 15m wide, 8m high, and 6m thick; the rock mass between the front of the U-shaped anchor beam and the main bridge beam is 40m long; the angle between the main cable and the horizontal plane... 35°; Two anchor piles and a U-shaped anchor beam are cast in one piece with reinforced concrete.

[0042] The specific construction steps are as follows:

[0043] (1) Based on the design drawings, the site was leveled and the location of the bridgehead roadbed 1, anchor chamber 2 and U-shaped anchor beam 4 was determined.

[0044] (2) Mechanically or by blasting, excavate the anchor chamber 2, U-shaped anchor beam groove and main cable groove 7 in the rock mass 8, and perform shotcrete and consolidation grouting on the relatively broken rock mass;

[0045] (3) After the excavation of anchor chamber 2 and U-shaped anchor beam groove is completed, the anchor pile hole is manually excavated, the hole is cleaned and the steel bars are tied, the steel bars and embedded parts of U-shaped anchor beam 4 are installed, the formwork is installed, and the concrete is poured in one piece.

[0046] (4) After the concrete reaches the design age, install the fixed cable saddle 5 on the fixed cable saddle base that protrudes outward on the side of the U-shaped anchor beam 4 adjacent to the anchor chamber 2.

[0047] (5) Install the panel 9 and ball bearing row 11 that allow the corner saddle 6 to move on the contact surface between the corner of the U-shaped anchor beam 4 and the corner saddle 6, and on the saddle beam (4d, 4e), and then install the corner saddle 6.

[0048] (6) The two main cables (7a, 7b) of the suspension bridge are respectively introduced into the main cable groove (7c, 7d) to the corner saddle (6a, 6b), the main cables (7) are dispersed into strands and passed through the corner saddle 6 to turn to the fixed saddle 5, and the strands are tensioned one by one and then anchored to the fixed saddle 5.

[0049] (7) Glass roof of the main cable (7a, 7b) strands, angle saddle 6 and fixed saddle 5 and anchor chamber 2 for construction protection;

[0050] (8) Corrosion protection treatment of the main cable (7a, 7b) strands, installation of drainage facilities in anchor chamber 2 or drilling of drainage holes.

[0051] In this embodiment, the anchorage uses anchor piles 3, U-shaped anchor beams 4, and angle saddles 6 to transfer the load of the main cable 7. The load of the main cable 7 is transferred to the surrounding rock of the anchor piles 3 and the rock mass in front of the U-shaped anchor beams 4. The vertical component of the tension of the main cable 7 is balanced by the gravity of the frustum-shaped anchor piles 3, the pull-out force of the anchor piles 3, and the self-weight of the U-shaped anchor beams 4. The horizontal component of the tension of the main cable 7 is balanced by the horizontal resistance of the anchor piles 3 and the shear force of the rock mass. The construction procedure is simple, the earthwork excavation and concrete volume are small, the construction is convenient, the cost is low, the construction period is shortened, and the maintenance is convenient.

[0052] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0053] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A composite anchorage structure for a suspension bridge, characterized in that: It includes an anchor chamber (2) excavated in the roadbed (1) at the side of the suspension bridge, a reinforced concrete anchor pile (3) cast in one piece adjacent to the anchor chamber (2), and a U-shaped anchor beam (4) on the anchor pile (3). The U-shaped anchor beam (4) wraps around and is embedded in the rock mass (8) of the roadbed at the side of the suspension bridge. A fixed cable saddle (5) is set in the middle of the U-shaped anchor beam (4), and corner cable saddles (6) are set at the corners on both sides. The main cable (7) is anchored to the fixed cable saddle (5) after turning through the corner cable saddle (6). The U-shaped anchor beam (4) is an enlarged reinforced concrete structure, including an enlarged structure (4a), an upstream wing wall (4b) and a downstream wing wall (4c). The upstream wing wall (4b) and the downstream wing wall (4c) are located on both sides of the enlarged structure (4a) and form a U-shaped structure with each other.

2. The composite anchorage structure for suspension bridges according to claim 1, characterized in that: Corner saddles (6) are provided at the corners of the enlarged structure (4a) and the upstream wing wall (4b) and the downstream wing wall (4c); the fixed saddle (5) is located in the middle of the enlarged structure (4a).

3. The composite anchorage structure for suspension bridges according to claim 1, characterized in that: The U-shaped anchor beam (4) is an outwardly convex arc shape on the side adjacent to the anchor chamber (2), and is slightly higher than the two ends of the U-shaped anchor beam (4).

4. The composite anchorage structure for suspension bridges as described in claim 3, characterized in that: When used for cable-stayed suspension, the main cable (7) is inclined, and the bottom surface of the U-shaped anchor beam (4) used to install the fixed cable saddle (5) is an inclined surface perpendicular to the main cable (7).

5. The composite anchorage structure for suspension bridges as described in claim 3, characterized in that: When used for horizontal suspension, the main cable (7) is horizontal, and the bottom surface of the U-shaped anchor beam (4) used to install the fixed cable saddle (5) is vertical. The main cable (7) is excavated through the main cable groove on both sides of the rock mass in front of the U-shaped anchor beam (4) to the main bridge (10).

6. The composite anchorage structure for suspension bridges as described in claim 1, characterized in that: The top surface of the U-shaped anchor beam (4) is at the same elevation as the top surface of the rock mass (8) it encloses, and it also serves as the roadbed for the approach bridge.

7. The composite anchorage structure for suspension bridges as described in claim 1, characterized in that: The anchor pile (3) and the U-shaped anchor beam (4) form a U-shape on the elevation. The rock mass (8) between the U-shaped anchor beam (4) and the side end of the main bridge (10) also serves as a component of the bridgehead roadbed (1) and the composite anchor structure.

8. The composite anchorage structure for suspension bridges as described in claim 1, characterized in that: The number of anchor piles (3) is 2 to 3. The U-shaped anchor beam (4) is symmetrical about the longitudinal axis of the main beam of the bridge. The anchor pile (3) is a truncated cone structure with a larger bottom and a smaller top, making full use of the pull-out resistance of the deep rock mass.

9. A method for constructing a composite anchorage structure for a suspension bridge as described in any one of claims 1 to 8, comprising the following steps: 1) Determine the location of the anchorage chamber (2) of the suspension bridge according to the design drawings and construction layout. Excavate the anchorage chamber and U-shaped anchor beam (4) groove on the rock subgrade using manual or mechanical or smooth blasting techniques. Drill anchor pile holes manually or mechanically, and spray anchor and consolidate grouting for the broken surrounding rock. 2) After the excavation is completed, clean the anchor pile holes, tie the reinforcing bars, install the embedded parts of the corner cable saddle (6) and the fixed cable saddle (5), pour the reinforced concrete anchor pile (3) and U-shaped anchor beam (4) in one piece, and spray anchor or pour the anchor chamber (2) for support. 3) After the concrete reaches the design age, install corner saddles (6) on the corner section of the U-shaped anchor beam (4) and install fixed saddles (5) in the middle of the crossbeam of the U-shaped anchor beam (4). 4) The main cable (7) of the suspension bridge is led to the corner saddle (6) and the fixed saddle (5) and anchored to the fixed saddle (5); 5) Ancillary facilities such as protective glass canopies for the main cable strands, angle saddles (6) and fixed saddles (5) during construction protection; 6) Main cable (7) Anti-corrosion treatment, installation of drainage facilities for anchor chamber or drilling of drainage holes.

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