A composite anchoring structure of suspension bridge tunnel anchor and rock anchor and construction method

Abstract

The present invention provides a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor and a construction method. The composite anchoring structure comprises a main cable access hole arranged in the bridge area of ​​the suspension bridge, a loose cable saddle chamber, a front anchor chamber and a rear anchor chamber which are sequentially constructed through the main cable access hole, a front anchor body, an anchor plug body, a rear anchor body and a plurality of anchor cables are arranged between the front anchor chamber and the rear anchor chamber, the front anchor body is placed on the front anchor surface of the anchor plug body and has an area larger than the front anchor surface of the anchor plug body, the rear anchor body is placed on the rear anchor surface of the anchor plug body and has an area larger than the rear anchor surface of the anchor plug body, and a plurality of anchor cables are fixed to the rear anchor body through anchors after passing through the anchor plug body and the rock mass around the anchor plug body from the front anchor body; the main cable of the suspension bridge is pulled into the loose cable saddle chamber from the main cable access hole and then dispersed through the loose cable saddle and connected to the corresponding anchor cable. The present invention increases the range of rock mass bearing, improves the anchor bearing capacity, can reduce the size of the anchor hole, and can be applied to rock mass with poor engineering quality level.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering, and relates to a suspension bridge anchor structure, in particular to a suspension bridge tunnel anchor and rock anchor composite anchor structure and a construction method. Background Art

[0002] At present, the anchorage structures of suspension bridges mainly include gravity anchorage, tunnel anchorage, composite anchorage of gravity anchorage (tunnel anchorage) + anchor cable, rock anchor, rock and reinforced concrete plate anchorage and concrete beam rock anchor. Gravity anchorage is used in soft rock foundations, relying on the friction between its own weight and the foundation to resist the tension of the main cable. The amount of earthwork excavation and concrete construction is large, and the impact on the ecological environment is also large. Tunnel anchorage is usually built in relatively hard or intact rock mass, and most of the tension in the main cable is transferred to the surrounding rock through the anchor body. The amount of earthwork excavation, concrete construction and the impact on the ecological environment are smaller than those of gravity anchorage, but the tunnel anchorage required for large-tonnage bridges is still large, and the amount of cavern excavation and concrete pouring is also large. The pull-out test of the similar scale model of the tunnel anchorage shows that most of the main cable tension is transferred to the surrounding rock by shear friction through the side walls around the middle and rear part of the anchor body, accounting for about 70% of the main cable tension. Lengthening the anchor body cannot significantly improve the bearing capacity of the anchor body, and the surrounding rock itself is not fully loaded. The safety stability coefficient of the surrounding rock of the built tunnel anchorage is mostly greater than 7, and some even reach 10 to 50. The composite anchorage of the tunnel anchorage + anchor cable is to transfer part of the load to the rock mass by adding anchor cables at the rear of the gravity anchorage or tunnel anchorage. The output of the anchor cable and the anchor body is not easy to coordinate, the durability of the anchor cable is difficult to guarantee, and the force is uneven.

[0003] In order to solve the problem that the output of anchor cables and anchor bodies is not easy to coordinate, and the earthwork and concrete engineering volume is large, the patent with authorization announcement number CN105648921 B discloses a construction method of composite anchorage of rock mass and reinforced concrete slab of suspension bridge, which specifically discloses a composite anchorage of rock mass and reinforced concrete slab. Through the anchor cable anchored on the reinforced concrete slab, the tension of the main cable of the suspension bridge is directly transmitted to the rock mass, which has safe and reliable performance, saves cost, and is beneficial to environmental protection. Rock anchors, composite anchorages of rock mass and reinforced concrete slab, and concrete beam rock anchors require a large number of anchor cable holes, which weakens the integrity of the rock mass. They are only applicable to rock masses with higher engineering quality levels of I to III, and are less used and lack experience.

[0004] With the development of the national economy and the needs of transportation engineering construction, double-deck, dual-use highway and railway, large-span, and large-tonnage suspension bridges will not only emerge, but also the tension of a single main cable will reach or exceed 50,000 tons, and some even approach 100,000 tons. This puts higher requirements on the bearing capacity of anchors. The use of the above anchors will inevitably increase the anchor volume or increase the number of anchor cables. However, due to the limitations of the line and topography, the tunnel anchors often need to be built in the IV-V rock mass with lower engineering quality level. For bridges with large spans and large tonnage loads, the anchors have larger volumes, and some anchor holes are more than 24 meters high. At this time, it is extremely difficult to form a hole, which poses a great safety hazard. The hole excavation and concrete volume increase significantly, the investment is huge, the construction period is long, and the risk is high. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a composite anchor structure of a suspension bridge tunnel anchor and a rock anchor and a construction method thereof. The composite anchor retains the bearing characteristics of a traditional tunnel anchor body and effectively utilizes the rock mass around the anchor plug body, reduces the cross-sectional size of the anchor plug body chamber, reduces the amount of hole excavation and concrete, and correspondingly improves the bearing capacity of the anchor and reduces the project cost.

[0006] In order to achieve the above technical objectives, the technical solution provided by the present invention is a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor, the composite anchoring structure comprising a main cable access hole arranged in the bridge area of ​​the suspension bridge, a loose cable saddle chamber, a front anchor chamber and a rear anchor chamber sequentially constructed through the main cable access hole, a front anchor body, an anchor plug body, a rear anchor body and a plurality of anchor cables are arranged between the front anchor chamber and the rear anchor chamber, the front anchor body is placed on the front anchor surface of the anchor plug body, and its area is larger than the front anchor surface of the anchor plug body, the rear anchor body is placed on the rear anchor surface of the anchor plug body, and its area is larger than the rear anchor surface of the anchor plug body, and a plurality of anchor cables are fixed to the rear anchor body through anchors after passing through the anchor plug body and the rock mass around the anchor plug body from the front anchor body; the main cable of the suspension bridge is pulled into the loose cable saddle chamber from the main cable access hole, and then dispersed into main cable strands with the same number as the number of anchor cables through the loose cable saddle, and each main cable strand is connected to the corresponding anchor cable through an anchor connector.

[0007] A further technical solution of the present invention is as follows: the cross-section of the anchor plug body is in the shape of a city gate, a horseshoe or a circle, and its cross-sectional area gradually increases from the front anchor surface to the rear anchor surface, forming a wedge-shaped body which is small at the front and large at the rear; the anchor plug body and the rear anchor body form a tunnel anchor, the front anchor body is separated from the anchor plug body, and together with the rear anchor body and the rock mass around the anchor plug body, form a rock anchor wrapped outside the tunnel anchor under the action of the anchor cable.

[0008] A more preferred technical solution of the present invention: the cross-sections of the front anchor body and the rear anchor body are the same as the cross-section shape of the anchor plug body, the anchor plug body and the rear anchor body are an integrated reinforced concrete structure, the front anchor body is placed around the front side of the front anchor surface of the anchor plug body, and the rear anchor body and the anchor plug body are connected by an arc-shaped or hemispherical curved surface.

[0009] The preferred technical solution of the present invention is as follows: backfilling concrete in the area of ​​the front anchor chamber corresponding to the front anchor body being larger than the front anchor surface of the anchor plug body to form a front anchor chamber reinforcement body; the multiple anchor cables are evenly distributed in a ring shape in the anchor plug body and the rock mass between the outer edge connection line of the front anchor body and the rear anchor body outside the anchor plug body, and form a rock anchor wrapped outside the tunnel anchor with the rock mass between the outer edge connection line of the anchor plug body and the front anchor body and the rear anchor body; an anchor cable pipe is pre-buried in the anchor plug body, anchor cable holes are set in the front anchor body, the rock mass around the anchor plug body, the rear anchor body and the front anchor chamber reinforcement body, and the anchor cable pipe is installed in the anchor cable hole, the anchor cable pipe in the rock mass and the anchor cable pipe in the front anchor chamber reinforcement body are connected in the front anchor chamber reinforcement body in a tangent manner with rounded corners or arcs, and the multiple anchor cables pass through the anchor plug body and the rock mass around the front reinforcement body and the anchor plug body from the anchor cable pipes of the front anchor surface and the front anchor chamber reinforcement body respectively, and are fixed to the rear anchor body through anchors.

[0010] The preferred technical solution of the present invention is as follows: the multiple anchor cables pass through the anchor cable tube and the anchor cable hole to the rear anchor chamber and are anchored on the rear anchor body with an anchor, the front end of the anchor cable in the tunnel anchor is fixed to the front anchor surface of the tunnel anchor with an anchor, the anchor cable in the rock anchor is fixed to the front anchor chamber reinforcement body, and each main cable strand is connected to the corresponding anchor through an anchor connector; the front anchor chamber reinforcement body is a reinforcement structure formed by backfilling reinforced concrete after the main cable strands are connected to the anchor cables at the front end surface of the front anchor body.

[0011] In the present invention, the resultant force line of the anchor plug body coincides with the resultant force line of the main cable, and the cross-sectional resultant force point of the front anchor body and the cross-sectional resultant force point of the rear anchor body are both on the main cable resultant force line.

[0012] The present invention provides a method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor, which is characterized by the following specific steps:

[0013] (1) The position of the front anchor chamber is determined according to the design drawings and construction layout, a main cable access hole is excavated on the mountain slope on one or both sides of the suspension bridge, and a loose cable saddle chamber, a front anchor chamber, a front anchor body chamber, an anchor body chamber and a rear anchor chamber in the shape of a city gate are excavated by smooth blasting; the size of the anchor body chamber is constructed according to the size of the anchor plug body and the rear anchor body, the front anchor chamber expands outward from the bottom of the loose cable saddle chamber to the same width as the front anchor body chamber, the rear anchor chamber is the same width as the part of the anchor body chamber corresponding to the rear anchor body, and the cross-section of the anchor body chamber is in the shape of a city gate, a horseshoe or a circle;

[0014] (2) Start to reinforce the broken surrounding rock of the front anchor chamber by spraying anchors and grouting, carry out initial spraying anchor support for the front anchor body chamber and anchor body chamber, carry out local small pipe grouting, set up steel arch frame to support the surrounding rock section, reinforce the surrounding rock of the rear anchor chamber by spraying anchors and grouting, and use concrete lining for the main cable access hole, loose cable saddle chamber, front anchor chamber and rear anchor chamber;

[0015] (3) After the excavation of the anchor body chamber and the rear anchor chamber is completed and the bottom is cleared, the anchor cable pipe and steel bars are accurately positioned and installed in the anchor body chamber. The anchor cable pipe extends radially to the front anchor surface, and the combined force point is at the center of the loose cable saddle; a grouting pipe is pre-buried between the contact surface between the anchor plug and the rock mass, the rear anchor surface template is installed, and the micro-expansion concrete is poured in layers and compacted, and the concrete is cured to form an integrated anchor body structure consisting of the anchor plug and the rear anchor body;

[0016] (4) According to the design drawings and construction layout, the steel bars are installed in the front anchor body room, the steel pipes are embedded in the drilling position, and then the concrete is poured. After the concrete strength reaches the design strength, the anchor cable holes are drilled from the embedded steel pipes to the rear anchor surface by a drilling rig. During this period, the rock mass with broken and poor integrity is reinforced by grouting to improve the integrity and bearing capacity of the rock mass.

[0017] (5) Anchor cables are installed in the anchor cable holes. An anchor cable pipe is installed outside the front anchor body to the front anchor chamber of the rock mass. Then, the area of ​​the front anchor chamber corresponding to the front anchor body larger than the front anchor surface of the anchor plug body is backfilled with reinforced concrete to form a front anchor chamber reinforcement body.

[0018] (6) Excavate the loose cable saddle foundation in the loose cable saddle room, cast the loose cable saddle reinforced concrete base, install the loose cable saddle after reaching the design strength, and then pull the main cable of the suspension bridge into it, disperse it into main cable strands with the same number of anchor cables through the loose cable saddle, and connect the anchor cables one by one with the main cable strands using anchor connectors;

[0019] (7) After the concrete of the anchor plug body reaches the design strength, the anchor is installed on the surface of the rear anchor body. Starting from the center anchor cable, the anchor cables are tensioned symmetrically layer by layer toward the outer circle. After a single anchor cable reaches its design load, it is anchored to the anchor plug body with the anchor until all the anchor cables are tensioned and anchored. Finally, the anchor cable anti-corrosion and lubrication oil is poured into the anchor cable tube to complete the construction of the composite anchor structure.

[0020] The middle part of the composite anchor in the present invention is an inverted wedge-shaped anchor plug body with a small front and a large rear and a cross-section of a city gate hole, a circle or a horseshoe. A front anchor body with an area larger than that of the front end face of the anchor plug body is provided on the front end face of the anchor plug body, and a rear anchor body with an area larger than that of the rear end face is provided on the rear end face of the anchor plug body. The anchor cable is distributed in the anchor plug body and the rock mass around the anchor plug body. The front anchor body is separated from the anchor plug body, and the anchor plug body and the rear anchor body are integrally cast with reinforced concrete. The expanded part of the front anchor chamber outside the front anchor surface of the anchor plug body is filled with reinforced concrete to form a front anchor chamber reinforcement body. The front anchor body, the rear anchor body and the rock mass between the two and the outer edge of the anchor plug body form an annular rock anchor body. The anchor structure in the present invention not only retains the bearing characteristics of the traditional tunnel anchor body, but also effectively utilizes the rock mass around the anchor plug body, reduces the cross-sectional size of the anchor hole, reduces the amount of hole excavation and concrete, and correspondingly improves the bearing capacity of the anchor. Under the same surrounding rock grade and bearing capacity, the composite anchor is shorter than the traditional tunnel anchor, which can shorten the length of the cavern and reduce the cross-section of the cavern, thereby reducing the amount of tunnel excavation and concrete, reducing the project cost and shortening the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A vertical cross-sectional view of the anchoring structure of the present invention;

[0022] Figure 2 yes Figure 1 Middle AA section view;

[0023] Figure 3 yes Figure 1 Middle BB section view.

[0024] In the figure: 1—main cable access hole, 2—loose cable saddle chamber, 3—front anchor chamber, 4—front anchor body, 5—anchor plug body, 6—rear anchor body, 7—rear anchor chamber, 8—main cable, 9—loose cable saddle, 10—anchor cable, 11—main cable strand, 12—anchor connector, 13—rock mass, 14—anchor, 15—anchor cable hole, 16—anchor cable tube, 17—front anchor chamber reinforcement body. DETAILED DESCRIPTION

[0025] The specific implementation of the technical solution in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.

[0026] Figures 1 to 3 The following is a diagram of a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor in an embodiment, which is drawn in a simplified manner and is only used to clearly and concisely illustrate the purpose of the embodiment of the present invention. The following technical solutions shown in the accompanying drawings are specific solutions of the embodiments of the present invention and are not intended to limit the scope of the invention claimed for protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0028] A composite anchor structure of a suspension bridge tunnel anchor and a rock anchor is provided in the embodiment, such as Figures 1 to 3As shown, the composite anchoring structure comprises a main cable access hole 1 arranged in the bridge area of ​​the suspension bridge, a loose cable saddle chamber 2, a front anchor chamber 3 and a rear anchor chamber 7 which are sequentially constructed through the main cable access hole 1, a front anchor body 4, an anchor plug body 5, a rear anchor body 6 and a plurality of anchor cables 10 are arranged between the front anchor chamber 3 and the rear anchor chamber 7, the cross section of the anchor plug body 5 is in the shape of a city gate, a horseshoe or a circle, and its cross-sectional area gradually increases from the front anchor surface to the rear anchor surface, forming a wedge-shaped body with a small front and a large rear; the front anchor body 4 is placed on the front anchor surface of the anchor plug body 5, and its area is larger than the front anchor surface of the anchor plug body 5, the rear anchor body 6 is placed on the rear anchor surface of the anchor plug body 5, and its area is larger than the rear anchor surface of the anchor plug body 5, the cross sections of the front anchor body 4 and the rear anchor body 6 are the same as the cross section of the anchor plug body 5, and the contact surface between the rear anchor body 6 and the anchor plug body 5 is an arc-shaped or hemispherical curved surface. The anchor body 5 and the rear anchor body 6 are an integrated reinforced concrete structure, forming a tunnel anchor, the front anchor body 4 is placed around the front anchor surface of the anchor body 5, and concrete is backfilled in the area of ​​the front anchor chamber 3 corresponding to the front anchor body 4 being larger than the front anchor surface of the anchor body 5 to form a front anchor chamber reinforcement body 17; multiple anchor cables 10 pass through the anchor body 5 and the rock mass 13 around the front reinforcement body 4 and the anchor body 5 from the front anchor surface and the anchor cable tube 16 of the front anchor chamber reinforcement body 17, and are fixed to the rear anchor body 6 through the anchor 14, the front end of the anchor cable 10 in the tunnel anchor is fixed to the front anchor surface of the tunnel anchor with an anchor, and the anchor cable 10 in the rock anchor is fixed to the front anchor chamber reinforcement body 17. A plurality of anchor cables 10 are evenly distributed in a ring shape in the rock mass 13 between the anchor body 5 and the outer edge connecting line of the front anchor body 4 and the rear anchor body 6 outside the anchor body 5, and form a rock anchor with the rock mass 13 between the outer edge connecting line of the front anchor body 4 and the rear anchor body 6 outside the anchor body 5; the anchor cables distributed in the anchor body 5 pass through the anchor cable tube pre-installed in the anchor body 5, and the anchor cables distributed in the rock mass 13 outside the anchor body 5 pass through the anchor cable tube 16 in the anchor cable hole 15 pre-drilled in the rock mass 13, and the front ends of the plurality of anchor cables 10 are respectively fixed to the front end surface of the front anchor body 4 by anchors 14, and the anchor cables 10 in the rock mass 13 pass through the anchor cable tube 16 in the front anchor chamber reinforcement body 17, and the anchor cable tube 16 in the rock mass and the anchor cable tube 16 in the front anchor chamber reinforcement body 17 are connected in the front anchor chamber reinforcement body 17 by means of fillet or arc tangency. The main cable 8 of the suspension bridge is pulled from the main cable access hole 1 into the cable saddle chamber 2 and then dispersed into main cable strands 11 having the same number as the anchor cables 10 through the cable saddle 9, and each main cable strand 11 is connected to the corresponding anchor cable 10 through the anchor connector 12. The resultant force line of the anchor plug body 5 coincides with the resultant force line of the main cable 8, and the cross-sectional resultant force point of the front anchor body 4 and the cross-sectional resultant force point of the rear anchor body 6 are both on the main cable 8 resultant force line.

[0029] The following is a detailed description of the construction method of the composite anchor structure of the suspension bridge tunnel anchor and rock anchor in the present invention in conjunction with a specific engineering example. The example includes a composite anchor arranged on one or both sides of the mountain of the suspension bridge. The engineering geological conditions and the physical and mechanical parameters of the rock mass and concrete are as follows: schist, flaky structure, weakly weathered to strongly weathered, poor rock integrity, relatively broken to broken, no groundwater development, no controlled unfavorable structural surface, the rock mass engineering quality level is mostly IV level, and locally V level; rock mass weight γ = 2.48g / cm 3 , saturated uniaxial compressive strength of rock mass R c =15~30MPa, average value of rock deformation modulus E o =7.5MPa, Poisson's ratio μ = 0.27, allowable bearing capacity of rock mass [f a ]=0.75MPa; rock mass shear strength f'=0.85, c=0.55MPa, shear strength f=0.45; rock mass and concrete shear strength f'=0.75, c=0.50MPa, shear strength f=0.40. A single main cable can bear 2.7×10 5 kN, 109 main cable strands, 127 strands, galvanized high-strength steel wire: diameter Φ5mm, standard strength R j b =1960MPa, PPWS method construction. Anchor concrete: design grade C40, slight expansion; 109 anchor cable tubes, all seamless steel tubes, inner diameter φ12cm, anchor cable tube material Q345.

[0030] Anchor structure and dimensions: main cable access section length 25m, loose cable saddle chamber length 5m, gate shape: width × height = 7m × 8m; anchor plug body: gate shape, length 45m (including rear anchor body length 5m); front anchor chamber, gate shape, length 10m; front anchor surface: gate shape, width × height = 6m × 8m (corresponding tunnel anchor rear anchor surface: gate shape, width × height = 7.8m × 9.8m ); rear anchor chamber: 2.5m long; rear anchor body: 8.71m thick, gate-shaped curved body, width × height = 16.24m × 18.24m, curved body radius 9.12m, arc radius tangent to the side and curved surface of the anchor plug body 2.00m; front anchor body: 3m thick, gate-shaped, width × height = 14m × 16m; the angle between the resultant force line of the main cable and the anchor body and the horizontal plane is ∠37°.

[0031] The specific construction steps are as follows:

[0032] (1) The position of the front anchor chamber is determined according to the design drawings and construction layout, and the main cable access hole 1 is excavated on the mountain slope on one or both sides of the suspension bridge. The loose cable saddle chamber 2, the front anchor chamber 3, the front anchor chamber, the anchor chamber and the rear anchor chamber 7 in the shape of a gate hole are excavated by smooth blasting; the size of the anchor chamber is constructed according to the size of the anchor plug body and the rear anchor body, the front anchor chamber expands outward from the bottom of the loose cable saddle chamber to the same width as the front anchor chamber, the rear anchor chamber is consistent with the width of the part of the anchor chamber corresponding to the rear anchor body, and the cross-section of the anchor chamber is in the shape of a gate hole, horseshoe or circle; the broken surrounding rock of the front anchor chamber 3 is reinforced by spraying and grouting, the anchor plug chamber is supported by initial spraying and grouting, and a steel arch frame is erected on the surrounding rock section to support the surrounding rock, the surrounding rock of the rear anchor chamber 7 is reinforced by spraying and grouting, and the main cable access hole 1, the loose cable saddle chamber 2, the front anchor chamber 3 and the rear anchor chamber 7 are lined with concrete;

[0033] (2) After the excavation of the anchor body chamber 5 and the rear anchor body 5 is completed and the bottom is cleared, 27 anchor cable tubes 16 and steel bars are accurately positioned and installed in the rear anchor body 5 and the anchor plug chamber 5. The anchor cable tubes 16 extend radially to the front anchor surface, and the combined force point is at the center of the loose cable saddle 9. A grouting pipe is pre-buried between the contact surface of the anchor plug body 5 and the rock mass 13, and the rear anchor surface template is installed. The micro-expansion concrete is poured in layers, vibrated and compacted, and the concrete is cured to form an integrated anchor plug body composed of the anchor plug body 5 and the rear anchor body 6.

[0034] (3) According to the design drawings and construction layout, steel bars are installed in the front anchor body 4, and steel pipes with an inner diameter of φ15 cm are pre-buried at the drilling site. The number of holes is 82, and then concrete is poured. After the concrete strength reaches the design strength, anchor cable holes 13 are drilled from the pre-buried steel pipe to the rear anchor surface through a drilling rig. During this period, grouting is performed to reinforce the broken rock mass and the rock mass with poor integrity to improve the integrity and bearing capacity of the rock mass.

[0035] (4) Anchor cables 10 are installed in the anchor cable holes 13. An anchor cable tube is installed outside the front anchor body 4 to the front anchor chamber 3 in the rock mass. The enlarged part of the front anchor chamber 3 is then filled with reinforced concrete to form a front anchor chamber reinforcement body 17.

[0036] (5) Excavate the foundation of the loose cable saddle 9 in the loose cable saddle chamber 2, cast the reinforced concrete base of the loose cable saddle 9, install the loose cable saddle 9 after reaching the design strength, and then pull the main cable 8 of the suspension bridge into it, disperse it into 109 main cable strands 11 through the loose cable saddle 9, and use anchor connectors to connect the anchor cables 10 to the main cable strands 11 one by one;

[0037] (6) After the concrete of the anchor plug body 5 reaches the design strength, a P-type anchor is installed on the surface of the rear anchor body 6. Starting from the center anchor cable, the anchor cables are tensioned symmetrically layer by layer toward the outer circle. After a single anchor cable reaches its design load, it is anchored to the anchor plug body with an anchor 14 until all the anchor cables are tensioned and anchored. Finally, the anchor cable anti-corrosion and lubricating oil is poured into the anchor cable tube 16.

[0038] In the anchorage of this embodiment, the anchor plug with a smaller cross-section size is wrapped by the rock mass, and the anchor plug is separated from the front anchor body, retaining the bearing mechanism of the traditional tunnel anchor. At the same time, under the action of the rear anchor body with a larger area and an arc shape, the tunnel anchor and the rock anchor can cooperate to bear the load. The outer edge of the rear anchor body increases the bearing area of ​​the anchorage, and the stress diffusion effect of the arc body overcomes the limitation of the plate (beam) anchorage that only uses the rock mass in front to bear the load, reduces the stress concentration of the surrounding rock, and further expands the bearing range of the surrounding rock. This composite anchorage can be built in the surrounding rock with poor rock properties. Although there are a large number of anchor cable holes, the amount of excavation and concrete is less than that of the traditional tunnel anchor hole, the project cost is low, the construction period is short, and the construction risk is small.

[0039] The above is only one embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the attached claims.

Claims

1. A method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor, characterized in that: The composite anchoring structure comprises a main cable access hole (1) arranged in the bridge area of ​​the suspension bridge, a loose cable saddle chamber (2), a front anchor chamber (3) and a rear anchor chamber (7) which are sequentially constructed through the main cable access hole (1), a front anchor body (4), an anchor plug body (5), a rear anchor body (6) and a plurality of anchor cables (10) are arranged between the front anchor chamber (3) and the rear anchor chamber (7), the front anchor body (4) is arranged on the front anchor surface of the anchor plug body (5) and has an area larger than the front anchor surface of the anchor plug body (5), and the rear anchor body (6) is arranged on the rear anchor surface of the anchor plug body (5). The area of ​​the anchor plug body (5) is larger than the rear anchor surface of the anchor plug body (5); a plurality of anchor cables (10) pass through the anchor plug body (5) and the rock mass (13) around the anchor plug body (5) from the front anchor body (4) and are fixed to the rear anchor body (6) through anchors (14); the main cable (8) of the suspension bridge is pulled from the main cable access hole (1) into the cable saddle chamber (2) and then dispersed into main cable strands (11) of the same number as the anchor cables (10) through the cable saddle (9); each main cable strand (11) is connected to the corresponding anchor cable (10) through an anchor connector (12); The construction method of the composite anchor structure of the suspension bridge tunnel anchor and rock anchor comprises the following specific steps: (1) The position of the front anchor chamber is determined according to the design drawings and construction layout, and a main cable access hole is excavated on the mountain slope on one or both sides of the suspension bridge. The loose cable saddle chamber, the front anchor chamber, the front anchor chamber, the anchor chamber and the rear anchor chamber in the shape of a city gate are excavated by smooth blasting. The size of the anchor chamber is constructed according to the size of the anchor plug and the rear anchor. The front anchor chamber expands outward from the bottom of the loose cable saddle chamber to the same width as the front anchor chamber. The rear anchor chamber has the same width as the part of the anchor chamber corresponding to the rear anchor, and the cross-section of the anchor chamber is in the shape of a city gate, a horseshoe or a circle. (2) Start to reinforce the broken surrounding rock of the front anchor chamber by anchor spraying and grouting, carry out initial anchor spraying support for the front anchor body chamber and anchor body chamber, carry out local small pipe grouting, set up steel arch frame to support the surrounding rock section, reinforce the surrounding rock of the rear anchor chamber by anchor spraying and grouting, and use concrete lining for the main cable access hole, loose cable saddle chamber, front anchor chamber and rear anchor chamber; (3) After the excavation of the anchor body chamber and the rear anchor chamber is completed and the bottom is cleared, the anchor cable pipe and steel bars are accurately positioned and installed in the anchor body chamber. The anchor cable pipe extends radially to the front anchor surface, and the combined force point is at the center of the loose cable saddle; the grouting pipe is pre-buried between the contact surface between the anchor plug and the rock mass, the rear anchor surface formwork is installed, and the micro-expansion concrete is poured in layers and compacted. The concrete is cured to form an integrated anchor body structure consisting of the anchor plug and the rear anchor body; (4) According to the design drawings and construction layout, steel bars are installed in the front anchor body room, steel pipes are embedded in the drilling position, and then concrete is poured. After the concrete strength reaches the design strength, anchor cable holes are drilled from the embedded steel pipe to the rear anchor surface through a drilling rig. During this period, grouting is performed to reinforce the broken rock mass and the rock mass with poor integrity to improve the integrity and bearing capacity of the rock mass; (5) Anchor cables are installed in the anchor cable holes. An anchor cable pipe is installed outside the front anchor body to the front anchor chamber in the rock mass. Then, the area of ​​the front anchor chamber corresponding to the front anchor body larger than the front anchor surface of the anchor plug body is backfilled with reinforced concrete to form a front anchor chamber reinforcement body. (6) Excavate the scattered cable saddle foundation in the scattered cable saddle room, cast the scattered cable saddle reinforced concrete base, install the scattered cable saddle after reaching the design strength, and then pull the main cable of the suspension bridge into it. The scattered cable saddle is used to disperse the main cable strands with the same number of anchor cables, and the anchor cables are connected to the main cable strands one by one with anchor connectors; (7) After the concrete of the anchor plug body reaches the design strength, the anchor is installed on the surface of the rear anchor body. Starting from the center anchor cable, the anchor cables are tensioned symmetrically layer by layer toward the outer circle. After a single anchor cable reaches its design load, it is anchored to the anchor plug body with the anchor until all the anchor cables are tensioned and anchored. Finally, the anchor cable anti-corrosion and lubrication oil is poured into the anchor cable pipe to complete the construction of the composite anchor structure.

2. The method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor according to claim 1, characterized in that: The cross section of the anchor plug body (5) is in the shape of a city gate, a horseshoe or a circle, and its cross-sectional area gradually increases from the front anchor surface to the rear anchor surface, forming a wedge-shaped body with a small front and a large rear. The anchor plug body (5) and the rear anchor body (6) form a tunnel anchor, and the front anchor body (4) is separated from the anchor plug body (5) and, under the action of the anchor cable (10), forms a rock anchor wrapped outside the tunnel anchor together with the rear anchor body (6) and the rock mass (13) surrounding the anchor plug body (5).

3. The method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor according to claim 1 or 2, characterized in that: The cross-sections of the front anchor body (4) and the rear anchor body (6) are the same as the cross-section of the anchor plug body (5); the anchor plug body (5) and the rear anchor body (6) are an integrated reinforced concrete structure; the front anchor body (4) is arranged around the front side of the front anchor surface of the anchor plug body (5); and the rear anchor body (6) and the anchor plug body (5) are connected by an arc-shaped or hemispherical curved surface.

4. The method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor according to claim 2, characterized in that: Concrete is backfilled in the area of ​​the front anchor chamber (3) corresponding to the front anchor body (4) larger than the front anchor surface of the anchor plug body (5) to form a front anchor chamber reinforcement body (17); the plurality of anchor cables (10) are evenly distributed in a ring shape in the rock mass (13) between the anchor plug body (5) and the outer edge connection line of the front anchor body (4) and the rear anchor body (6) outside the anchor plug body (5), and form a rock anchor wrapped outside the tunnel anchor with the rock mass (13) between the outer edge connection line of the anchor plug body (5) and the front anchor body (4) and the rear anchor body (6); an anchor cable tube (16) is pre-buried in the anchor plug body (5) and in the rock mass around the front anchor body (4) and the anchor plug body (5). Anchor holes (15) are provided in the rock body (13), the rear anchor body (6) and the front anchor chamber reinforcement body (17), and anchor pipes (16) are installed in the anchor holes (15). The anchor pipes (16) in the rock body (13) and the anchor pipes (16) in the front anchor chamber reinforcement body (17) are connected in the front anchor chamber reinforcement body (17) by means of fillets or arcs. A plurality of anchor cables (10) pass through the anchor plug body (5) and the rock body (13) around the front anchor body (4) and the anchor plug body (5) from the front anchor surface and the anchor pipes (16) of the front anchor chamber reinforcement body (17), and are then fixed to the rear anchor body (6) by means of anchors (14).

5. The method for constructing a composite anchoring structure of a suspension bridge tunnel anchor and a rock anchor according to claim 2, characterized in that: The plurality of anchor cables (10) pass through the anchor cable tube and the anchor cable hole to the rear anchor chamber (7) and are anchored on the rear anchor body (6) by means of an anchor. The front end of the anchor cable (10) in the tunnel anchor is fixed to the front anchor surface of the tunnel anchor by means of an anchor (14). The anchor cable (10) in the rock anchor is fixed to the front anchor chamber reinforcement body (17). Each main cable strand (11) is connected to the corresponding anchor (14) by means of an anchor connector (12). The front anchor chamber reinforcement body (17) is a reinforcement structure formed by backfilling reinforced concrete after the main cable strand (11) and the anchor cable (10) are connected at the front end surface of the front anchor body (4).

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