A multi-stage anchoring tunnel-type anchorage

Abstract

The application provides a multi-stage anchoring tunnel type anchorage which is buried in the stratum below the ground surface and comprises a cavern system, a main cable and strand system and an anchoring system. The anchoring system comprises at least two anchor bodies which are distributed in series along the axis of the main cable; the cavern system comprises subsidiary caverns which are arranged corresponding to the anchor bodies; the anchor bodies are located in the anchor holes of the subsidiary caverns, and a gallery is arranged in the middle part of the anchor hole, which is a passage for connecting the front anchor chamber to the rear anchor chamber after the anchor body is built; the main cable and strand system comprises a first main cable which constitutes the main cable of the bridge, and the first main cable is dispersed into strands through the subsidiary caverns of each stage; the strands in the subsidiary caverns of each stage are anchored to the anchor bodies through the prestressed steel strands to form a multi-stage load transmission path. The application effectively improves the bearing capacity by increasing the number of anchor bodies, so that the main cable load of large tonnage can be borne, and the application is particularly suitable for the anchoring of the main cable of a large-span suspension bridge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge engineering, and particularly relates to a multi-stage anchoring tunnel type anchorage. BACKGROUND

[0002] The tunnel type anchorage is a main ground anchor structure of a suspension bridge, and the anchor body is buried in the ground by excavating an anchor hole, and the anchor body and the surrounding rock jointly bear the bridge load. After nearly 30 years of development, the design and construction technology of the tunnel type anchorage has greatly improved, and is successfully applied to rock layers with different rock mass qualities, and the bridge load borne is gradually increased. In order to meet the need of anchoring of a large-tonnage bridge load, the method of increasing the size of the anchor body is usually adopted to improve the bearing capacity of the tunnel type anchorage.

[0003] Researches have shown that the method of simply increasing the size of the anchor body, such as changing the length and cross-sectional size of the anchor body, has a good effect on the improvement of the bearing capacity of the anchor body within a proper range, and the effect is not ideal when the range is exceeded. In addition, when the size of the anchor body is large, the stability of the anchor hole is poor, and the excavation and support are difficult. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a multi-stage anchoring tunnel type anchorage. The tunnel type anchorage of the present application effectively improves the bearing capacity by increasing the number of anchor bodies, and thus can bear the main cable load of a large-tonnage, and is particularly suitable for anchoring of the main cable of a large-span suspension bridge.

[0005] A multi-stage anchoring tunnel type anchorage comprises a chamber system, a main cable and strand system, and an anchoring system.

[0006] The anchoring system comprises at least two anchor bodies which are distributed in series along the axis of the main cable.

[0007] The chamber system comprises an auxiliary chamber corresponding to the anchor body, and the auxiliary chamber comprises a traffic hole, a front anchor chamber, an anchor hole, and a rear anchor chamber which are sequentially communicated. The anchor body is located in the anchor hole of the auxiliary chamber, and a corridor is arranged in the middle of the anchor hole. The corridor is a passage for communicating the front anchor chamber and the rear anchor chamber after the anchor body is constructed.

[0008] The main cable and strand system comprises a first main cable which constitutes the main cable of the bridge. The first main cable enters the front anchor chamber through the traffic hole of the first auxiliary chamber, and is dispersed into a plurality of strands and a second main cable. The second main cable enters the second auxiliary chamber through the corridor and the rear anchor chamber in the first auxiliary chamber, and is also dispersed in the same way until the last auxiliary chamber. The last auxiliary chamber only disperses the main cable into strands. The strands in each auxiliary chamber are anchored to the anchor body by prestressed steel strands to form a multi-stage load transmission path.

[0009] Further, the anchor body is a wedge-shaped body with a variable cross-section.

[0010] Further, the front anchor chamber is a passage connecting the traffic tunnel to the anchor tunnel, providing space for cable dispersion and anchor body construction.

[0011] Further, the anchor tunnel is a passage connecting the front anchor chamber to the rear anchor chamber, with a variable cross-section wedge-shaped outer surface, providing space for anchor body hosting.

[0012] Further, the rear anchor chamber is a passage connecting the anchor tunnel to the traffic tunnel in the next level of the auxiliary chamber, providing space for anchor body construction and maintenance during operation.

[0013] Further, the traffic tunnel, front anchor chamber, anchor tunnel, rear anchor chamber, and corridor all adopt straight wall semi-circular arch cross-sections with a width-to-height ratio close to or equal to 1.

[0014] Further, a cable dispersion saddle is provided at the intersection of the traffic tunnel and the front anchor chamber, where the main cable is dispersed into multiple strands.

[0015] Further, the anchoring system further includes front anchors and rear anchors for locking prestressed steel tendons, with the front anchors uniformly distributed in a ring shape on the front surface of the anchor body, and the rear anchors uniformly distributed in a ring shape on the rear surface of the anchor body.

[0016] Further, the number of anchor bodies is determined as follows:

[0017] (1) Obtain the design parameters of the anchor body:

[0018] Front anchor surface width and height: d1, h1;

[0019] Rear anchor surface width and height: d2, h2;

[0020] Corridor width and height: d3, h3;

[0021] Anchor body length L;

[0022] Anchor body elevation angle α;

[0023] Anchor body expansion angle β;

[0024] Main cable design load P;

[0025] Anchor body volume density γ;

[0026] Surrounding rock shear strength: cohesion C', internal friction angle f';

[0027] (2) Calculate the side area A and volume V of the anchor body based on the obtained design parameters of the anchor body:

[0028] The anchor body side area A calculation formula is as follows:

[0029] A = L × (C1 + C2) / 2

[0030] Where:

[0031] C1 = d1 + (h1 - d1 / 2) x 2 + π x d1 / 2

[0032] C2 = d2 + (h2 - d2 / 2) x 2 + π x d2 / 2

[0033] The anchor volume V is calculated as follows:

[0034] Wherein:

[0035] V = L x (S1 + S2) / 2 - L x S3

[0036] S1 = d1 x (h1 - d1 / 2) + π x (d1 / 2) 2 / 2

[0037] S2 = d2 x (h2 - d2 / 2) + π x (d2 / 2) 2 / 2

[0038] S3 = d3 x (h3 - d3 / 2) + π x (d3 / 2) 2 / 2

[0039] (3) According to the calculated anchor side area A and volume V, the allowable pull P1 of the anchor is calculated;

[0040] The calculation formula of P1 is as follows:

[0041] P1 = f' x W F + C' x A + W L

[0042] Wherein:

[0043] W F = V x γ x cos (α + β)

[0044] W L = V x γ x sin α

[0045] (4) According to the calculated allowable pull P1 of the anchor, the number n of anchors is calculated, and the anchor number calculation formula is as follows:

[0046] n = KP / P1

[0047] n is rounded up to be the number of anchors.

[0048] In the formula: K is the anchor pull safety factor.

[0049] Further, K is 2.

[0050] Compared with the prior art, the beneficial effects of the present application are:

[0051] 1. The tunnel type anchorage provided by the application can improve the bearing capacity by increasing the number of anchor bodies, and compared with the method of increasing the size of the anchor body, the improvement of the bearing capacity of the anchorage is effective and clear, which provides a relatively optimal new method for anchoring large-tonnage bridge load.

[0052] 2. The bridge main cable is anchored on the plurality of anchor bodies of the tunnel type anchorage, and the main cable load is borne in stages, the load value borne by each anchor body is low, and the anchoring system has good reliability.

[0053] 3. The steel beam of the anchoring system is distributed in the concrete between the inner corridor surface of the anchor body and the outer surface of the anchor body, the anchor body concrete is uniformly stressed, and the stability of the anchoring system is improved.

[0054] 4. The anchor body is internally provided with a corridor, which can provide a channel for the main cable to pass through, and can be used as a channel for personnel, pipelines and equipment to enter and exit during the operation period, without the need to excavate other pedestrian tunnels and drainage holes, so that the cost can be effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 Vertical sectional structure layout of the multi-stage anchoring tunnel type anchorage;

[0056] Figure 2 Inclined sectional anchor hole layout of the multi-stage anchoring tunnel type anchorage;

[0057] Figure 3 Traffic hole cross-sectional shape schematic diagram;

[0058] Figure 4 First stage anchor body rear anchor chamber and second stage corridor cross-sectional shape schematic diagram;

[0059] Figure 5 First stage and second stage anchor body internal anchoring system steel beam embedding schematic diagram;

[0060] Figure 6 First stage and second stage anchor body front shape and front anchor arrangement schematic diagram;

[0061] Figure 7 First stage and second stage anchor body tail shape and rear anchor arrangement schematic diagram. DETAILED DESCRIPTION

[0062] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0063] See also Figure 1 and Figure 2 An embodiment of the present invention provides a multi-stage anchor tunnel type anchor, which is buried in a stratum 2 below the surface 1 and includes a cavern system 3, a main cable and strand system 4 and an anchor system 5.

[0064] The cave system 3 includes a first traffic tunnel 31a, a first front anchor chamber 32a, a first anchor hole 33a, a first rear anchor chamber 34a, a first corridor 35a, a second traffic tunnel 31b, a second front anchor chamber 32b, a second anchor hole 33b, a second rear anchor chamber 34b and a second corridor 35b.

[0065] The first communication tunnel 31 a is a passage connecting the ground surface 1 to the first front anchor chamber 32 a.

[0066] The first front anchor chamber 32a is a passage connecting the first communication hole 31a to the first anchor hole 33a, providing a space for the first strands 43a to be dispersed and a space for the first anchor body 53a to be constructed.

[0067] The first anchor hole 33a connects the first forward anchor chamber 32a to the first aft anchor chamber 34a. Its outer surface has a variable-cross-section wedge shape, providing space for the first anchor body 53a. A first corridor 35a is located in the center of the first anchor hole 33a. After the first anchor body 53a is constructed, it becomes a passage connecting the first forward anchor chamber 32a to the first aft anchor chamber 34a.

[0068] The first rear anchor chamber 34a is a passage connecting the first anchor hole 33a to the second traffic hole 31b, providing space for the construction of the first anchor body 53a and space for maintenance during the operation period.

[0069] The second communication tunnel 31b is a passage connecting the first rear anchor chamber 34a to the second front anchor chamber 32b.

[0070] The second front anchor chamber 32b is a passage connecting the second communication hole 31b to the second anchor hole 33b, providing a space for the second strands 43b to be dispersed and a space for the second anchor body 53b to be constructed.

[0071] The second anchor hole 33b is a passage connecting the second front anchor chamber 32b to the second rear anchor chamber 34b, and the outer surface is a variable cross-section wedge shape, providing a space for the second anchor body 53b. The second corridor 35b is provided in the middle of the second anchor hole 33b, and after the second anchor body 53b is built, it is a passage connecting the second front anchor chamber 32b to the second rear anchor chamber 34b. The second rear anchor chamber 34b provides a space for the second anchor body 53b to be built, as well as a space for maintenance during operation.

[0072] Preferably, the traffic holes (31a, 31b), front anchor chambers (32a, 32b), anchor holes (33a, 33b), rear anchor chambers (34a, 34b), and corridors (35a, 35b) of the embodiments of the present application all adopt straight wall semi-circular arch cross-sections, with a width-height ratio close to or equal to 1, as shown in Figure 3 、 Figure 4 、 Figure 6 and Figure 7 .

[0073] The main cable and strand system 4 includes a first main cable 41a, a first strand saddle 42a, a first strand 43a, a second main cable 41b, a second strand saddle 42b, and a second strand 43b.

[0074] The first main cable 41a is the main component for transmitting the load of the bridge. After passing through the first strand saddle 42a, the first main cable 41a is dispersed into multiple first strands 43a and a second main cable 41b. The material of the first main cable 41a is steel strand.

[0075] The first strand 43a is an auxiliary component for transmitting the load of the bridge. The first strand 43a is connected to the first steel beam 52a, and transmits the load to the first anchor body 53a through the first steel beam 52a. The material of the first strand 43a is the same steel strand as the first main cable 41a.

[0076] The second main cable 41b is the main component for transmitting the load of the bridge. After passing through the second strand saddle 42b, the second main cable 41b is dispersed into multiple second strands 43b. The material of the second main cable 41b is the same steel strand as the first main cable 41a.

[0077] The second strand 43b is an auxiliary component for transmitting the load of the bridge. The second strand 43b is connected to the second steel beam 52b, and transmits the load to the second anchor body 53b through the second steel beam 52b. The material of the second strand 43b is the same steel strand as the second main cable 41b.

[0078] The anchoring system 5 includes a first front anchor 51a, a first steel beam 52a, a first anchor body 53a, a first rear anchor 54a, a second front anchor 51b, a second steel beam 52b, a second anchor body 53b, and a second rear anchor 54b.

[0079] The first front anchor 51a is annularly and uniformly distributed on the front surface of the first anchor body 53a, asFigure 6 As shown, it is a component for locking the first steel bundle 52a. The first front anchor 51a is composed of an anchor plate, an anchor ring and a clip. The anchor plate is embedded in the first anchor body 53a and is used to install the anchor ring and the clip.

[0080] The first steel bundle 52a is buried in the steel protective tube of the first anchor body 53a. Figure 5 The number of first steel strands 52a is equal to the number of first cable strands 43a. After being connected to the first cable strands 43a, the first steel strands 52a bear the bridge load and transfer it to the first anchor body 53a.

[0081] The first anchor body 53a is cast by concrete in the first anchor hole 33a, is a wedge-shaped body with a variable cross-section, and is the main load-bearing component.

[0082] The first rear anchors 54a are evenly distributed on the rear surface of the first anchor body 53a in an annular shape. Figure 7 As shown, this is the component that locks the first steel strand 52a and transmits the tension of the first steel strand 52a to the anchor body. The first rear anchor 54a consists of an anchor plate, an anchor ring, and a clip. The anchor plate is embedded in the concrete and is used to install the anchor ring and clip.

[0083] The second front anchors 51b are evenly distributed on the front surface of the second anchor body 53b in an annular shape. Figure 6 As shown, it is a component for locking the second steel bundle 52b. The second front anchor 51b is composed of an anchor plate, an anchor ring and a clip. The anchor plate is embedded in the second anchor body 53b and is used to install the anchor ring and the clip.

[0084] The second steel bundle 52b is buried in the steel protective tube of the second anchor body 53b. Figure 5 The number of second steel strands 52b is equal to the number of second strands 43b. After being connected to the second strands 43b, the second steel strands 52b bear the bridge load and transfer it to the second anchor body 53b.

[0085] The second anchor body 53b is cast by concrete in the second anchor hole 33b, is a wedge-shaped body with a variable cross-section, and is the main load-bearing component.

[0086] The second rear anchor 54b is located on the rear surface of the second anchor body 53b. Figure 7 As shown, it is a component that locks the second steel strand 52b and transmits the tension of the second steel strand 52b to the anchor body. The second rear anchor 54b consists of an anchor plate, an anchor ring, and a clip. The anchor plate is buried in the concrete and is used to install the anchor ring and clip.

[0087] The embodiment of the present invention further provides a method for constructing the above-mentioned multi-stage anchor tunnel anchor, comprising the following steps:

[0088] Step S1: Excavation and support of the cavern system 3 to form a through space. Step S1 specifically includes:

[0089] Step S11: excavate and support the first traffic tunnel 31a, the first front anchor chamber 32a, the first anchor tunnel 33a and the first rear anchor chamber 34a in sequence from the ground surface.

[0090] Step S12: excavating the second traffic tunnel 31b, the second front anchor chamber 32b, the second anchor hole 33b and the second rear anchor chamber 34b in sequence from the first rear anchor chamber 34a.

[0091] Step S2: Construction of anchoring system 5 and installation of equipment. Step S2 specifically includes:

[0092] Step S21: Use steel brackets to fix the anchor plate of the second front anchor 51b, the steel protective pipe of the second steel bundle 52b, and the anchor plate of the second rear anchor 54b, make the outer contour template of the second corridor 35b and the partition template for the second anchor body 53b to be cast in compartments, and cast and maintain the concrete of the second anchor body 53b multiple times until the casting is completed.

[0093] Step S22: Install and assemble all second steel strands 52b. Taking one second steel strand 52b as an example, the second steel strand 52b sequentially passes through the second front anchor 51b and the steel protective tube, reaches the second rear anchor 54b, and is secured with a clip. A tensioning device is used to tension the second steel strand 52b at the second front anchor 51b, and once the predetermined tension is reached, the second steel strand 52b is secured with a clip.

[0094] Step S23: Use steel brackets to fix the anchor plate of the first front anchor 51a, the steel protective pipe of the first steel bundle 52a, and the anchor plate of the first rear anchor 54a, make the outer contour template of the first corridor 35a and the partition template for the first anchor body 53a to be cast in compartments, and cast and maintain the concrete of the first anchor body 53a multiple times until the casting is completed.

[0095] Step S24: Install and assemble all first steel strands 52a. Taking one first steel strand 52a as an example, the first steel strand 52a sequentially passes through the first front anchor 51a and the steel protective tube, reaches the first rear anchor 54a, and is secured with a clip. A tensioning device is used to tension the first steel strand 52a at the first front anchor 51a, and once the predetermined tension is reached, the first steel strand 52a is secured with a clip.

[0096] Step S3: Installation of the main cable and the strand system 4. Step S3 specifically includes:

[0097] Step S31: Transport and assemble the cable saddles. Transport the second cable saddle 42b to the intersection of the second access tunnel 31b and the second front anchor chamber 32b, assemble and secure it to the bedrock at the tunnel bottom. Transport the first cable saddle 42a to the intersection of the first access tunnel 31a and the first front anchor chamber 32a, assemble and secure it to the bedrock at the tunnel bottom.

[0098] Step S32, the main cable 41 passes through the ground surface 1 from the first traffic tunnel 31a to the stratum 2, and is dispersed into a plurality of first cable strands 43a and a second main cable 41b at the first cable dispersion saddle 42a.

[0099] Step S33, the second main cable 41b passes through the first gallery 35a and the first rear anchor chamber 34a to the second traffic tunnel 31b, and is dispersed into a plurality of second cable strands 43b at the second cable dispersion saddle 42b.

[0100] Step S34, all the second cable strands 43b are connected to the second steel beam 52b, and all the first cable strands 43a are connected to the first steel beam 52a.

[0101] Step S4, anchor corrosion prevention and operation period maintenance. Step S4 specifically includes:

[0102] Step S41, anchor corrosion prevention treatment. The exposed surface of the concrete of the chamber system 3 is coated with a corrosion inhibitor, and the exposed steel strands and steel products of the main cable and cable strand system 4 and the anchoring system 5 are coated with corrosion-proof grease.

[0103] Step S42, anchor operation period maintenance. The first traffic tunnel 31a, the first gallery 35a, the second traffic tunnel 31b and the second gallery 35b are used as channels for personnel, pipelines and equipment to enter and exit the chamber system 3, ventilation and drainage equipment is installed in the first front anchor chamber 32a, the first rear anchor chamber 34a, the second front anchor chamber 32b and the second rear anchor chamber 34b, and long-term maintenance and management during the operation period is carried out.

[0104] The number of anchor bodies of the tunnel type anchor of the present application can be increased, and the above embodiments are described by taking two anchor bodies as an example. If the number of anchor bodies is increased, the number of first anchor bodies and the number of auxiliary chambers and anchoring equipment can be increased in proportion.

[0105] The embodiment of the present application also provides a calculation method for the number of anchor bodies:

[0106] (1) Obtain the design parameters of the anchor body

[0107] According to the design file of the anchor body, the parameters of the anchor body are as follows:

[0108] Front anchor surface width and height: d1, h1;

[0109] Rear anchor surface width and height: d2, h2;

[0110] Gallery width and height: d3, h3;

[0111] Anchor body length L;

[0112] Anchor body elevation angle α;

[0113] Anchor body expansion angle β;

[0114] Main cable design load P;

[0115] Anchor bulk density γ;

[0116] Surrounding rock shear strength: cohesion C', internal friction angle f';

[0117] (2) According to the design parameters of the obtained anchor, the side area A and the volume V of the anchor are calculated

[0118] The anchor side area A calculation formula is as follows:

[0119] A = L x (C1 + C2) / 2

[0120] Wherein:

[0121] C1 = d1 + (h1 - d1 / 2) x 2 + π x d1 / 2

[0122] C2 = d2 + (h2 - d2 / 2) x 2 + π x d2 / 2

[0123] The anchor volume V calculation formula is as follows:

[0124] Wherein:

[0125] V = L x (S1 + S2) / 2 - L x S3

[0126] S1 = d1 x (h1 - d1 / 2) + π x (d1 / 2) 2 / 2

[0127] S2 = d2 x (h2 - d2 / 2) + π x (d2 / 2) 2 / 2

[0128] S3 = d3 x (h3 - d3 / 2) + π x (d3 / 2) 2 / 2

[0129] (3) According to the calculated side area A and volume V of the anchor, the allowable pull P1 of the anchor is calculated

[0130] The calculation formula of P1 is as follows:

[0131] P1 = f' x W F + C' x A + W L

[0132] Wherein:

[0133] W F = V x γ x cos (α + β)

[0134] W L = V x γ x sin α

[0135] (4) According to the calculated allowable pull P1 of the anchor, the number n of anchors is calculated

[0136] The anchor quantity calculation formula is as follows:

[0137] n = KP / P1

[0138] n is rounded up to be the anchor quantity.

[0139] In the formula: K is the anchor body anti-pull safety factor, the value of which should not be less than 2 according to the Design Specification for Highway Suspension Bridges, so K is taken as 2.

[0140] A specific implementation case of calculating the anchor quantity is provided as follows:

[0141] (1) Obtain the design parameters of the anchor body

[0142] According to the design file of the anchor body, the parameters of the anchor body are obtained as follows:

[0143] Front anchor surface width and height: d1 = 6 m, h1 = 6 m

[0144] Rear anchor surface width and height: d2 = 10 m, h2 = 10 m

[0145] Corridor width and height: d3 = 2 m, h3 = 2 m

[0146] Anchor body length L = 30 m

[0147] Anchor body elevation angle a = 40°

[0148] Anchor body expansion angle b = 3.81°

[0149] Main cable design load P = 400000 kN

[0150] Anchor body volume weight y = 24 kN / m 3

[0151] Surrounding rock shear strength: C' = 700 kPa, f' = 0.81

[0152] (2) Calculate the side area A and volume V of the anchor body 2

[0153] Wherein:

[0154] C1 = d1 + (h1 - d1 / 2) x 2 + p x d1 / 2 = 21.4 m

[0155] C2 = d2 + (h2 - d2 / 2) x 2 + p x d2 / 2 = 35.7 m

[0156] The anchor body volume V is calculated as follows:

[0157] Wherein:

[0158] V = L x (S1 + S2) / 2 - L x S3 = 1713.6 m 3

[0159] S1 = d1 x (h1 - d1 / 2) + π x (d1 / 2) 2 / 2 = 32.1 m 2

[0160] S2 = d2 x (h2 - d2 / 2) + π x (d2 / 2) 2 / 2 = 89.3 m 2

[0161] S3 = d3 x (h3 - d3 / 2) + π x (d3 / 2) 2 / 2 = 3.6 m 2

[0162] (3) Calculate the allowable pull P1 of the anchor body, the calculation formula of P1 is as follows:

[0163] P1 = f' x W F + C' x A + W L = 650233.4 kN

[0164] Wherein:

[0165] W F = V x γ x cos (α + β) = 29676.4 kN

[0166] W L = V x γ x sin α = 26435.5 kN

[0167] (4) Calculate the number of anchor bodies

[0168] The calculation formula of the number of anchor bodies is as follows:

[0169] n = KP / P1 = 1.2

[0170] n is rounded up to 2, that is, the number of anchor bodies.

[0171] In the formula: K is the safety factor of the anchor body, the value thereof should not be less than 2 according to the Design Specification for Highway Suspension Bridge, therefore, K is taken as 2.

[0172] The anchor body and the auxiliary chamber are arranged in series on the axis of the bridge main cable, a corridor is arranged in the middle of the anchor body, so that all the chambers are connected in series. The main cable enters the stratum from the ground surface, passes through the traffic chamber and the corridor, reaches the front anchor chamber of each anchor body, is dispersed into a plurality of strands after passing through the spreader saddle, and is connected to the steel beam of the anchoring system, so that the load is transmitted to the plurality of anchor bodies to achieve the anchoring effect. The tunnel type anchor of the application has a large tonnage load bearing capacity, and is particularly suitable for anchoring the main cable of a large-span suspension bridge.

[0173] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application, which can be easily thought by any person skilled in the art, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multi-stage anchor tunnel anchor, characterized by: Buried in the ground below the surface, it includes a cavern system, main cable and strand system, and anchoring system; The anchoring system comprises at least two anchors distributed in series along the main cable axis; The cavern system includes an auxiliary cavern corresponding to the anchor body, and the auxiliary cavern includes a traffic tunnel, a front anchor chamber, an anchor hole, and a rear anchor chamber connected in sequence; the anchor body is located in the anchor hole of the auxiliary cavern, and a corridor is provided in the middle of the anchor hole. After the anchor body is constructed, the corridor serves as a passage connecting the front anchor chamber to the rear anchor chamber; The main cable and strand system includes a first main cable constituting the main cable of the bridge. The first main cable passes through the traffic tunnel of the first-level auxiliary cavern and enters the front anchor chamber to be dispersed into multiple strands and the second main cable; the second main cable passes through the corridor and the rear anchor chamber in the first-level auxiliary cavern and then enters the second-level auxiliary cavern to be dispersed in the same way until the last-level auxiliary cavern, where only the main cable is dispersed into strands; the strands in each level of the auxiliary cavern are anchored to the anchor body through prestressed steel strands to form a multi-level load transfer path.

2. The multi-stage anchor tunnel anchor according to claim 1, characterized in that: The anchor body is a wedge-shaped body with a variable cross-section.

3. The multi-stage anchor tunnel type anchor according to claim 1, characterized in that: The front anchor chamber is a passage connecting the traffic tunnel to the anchor tunnel, providing space for the cable strands to be dispersed and for the construction of the anchor body.

4. The multi-stage anchor tunnel anchor according to claim 1, characterized in that: The anchor hole is a passage connecting the front anchor chamber to the rear anchor chamber, and its outer surface is a wedge-shaped with a variable cross-section, providing a space for the anchor body to be stored.

5. The multi-stage anchor tunnel anchor according to claim 1, characterized in that: The rear anchor chamber is a passage connecting the anchor hole to the traffic hole in the next-level auxiliary cavern, providing space for anchor body construction and space for maintenance during operation.

6. The multi-stage anchor tunnel anchor according to claim 1, characterized in that: The traffic tunnel, front anchor room, anchor tunnel, rear anchor room and corridor all adopt straight wall semicircular arch section, and the width-to-height ratio of the section is close or equal.

7. The multi-stage anchor tunnel type anchorage according to claim 1, characterized in that: A saddle is provided at the intersection of the traffic tunnel and the front anchor chamber, and the main cable is dispersed into multiple cable strands at the saddle.

8. The multi-stage anchor tunnel anchor according to claim 1, characterized in that: The anchoring system further comprises a front anchor and a rear anchor for locking the prestressed steel bundle. The front anchor is evenly distributed in a circular shape on the front surface of the anchor body, and the rear anchor is evenly distributed in a circular shape on the rear surface of the anchor body.

9. The multi-stage anchor tunnel type anchor according to claim 1, characterized in that: The steps for determining the number of anchor bodies are as follows: (1) Obtain the design parameters of the anchor body: Front anchor width and height: d1, h1; Width and height of rear anchor surface: d2, h2; Corridor width and height: d3, h3; Anchor body length L; Anchor elevation angle α; Anchor body expansion angle β; Main cable design load P; Anchor body bulk density γ; Shear strength of surrounding rock: cohesion C', internal friction angle f'; (2) Based on the obtained design parameters of the anchor body, calculate the side area A and volume V of the anchor body: The calculation formula of the anchor body side area A is as follows: A=L×(C1+C2) / 2 in: C1=d1+(h1-d1 / 2)×2+π×d1 / 2 C2=d2+(h2-d2 / 2)×2+π×d2 / 2 The calculation formula of anchor body volume V is as follows: in: V=L×(S1+S2) / 2-L×S3 S1=d1×(h1-d1 / 2)+π×(d1 / 2) 2 / 2 S2=d2×(h2-d2 / 2)+π×(d2 / 2) 2 / 2 S3=d3×(h3−d3 / 2)+π×(d3 / 2) 2 / 2 (3) Calculate the allowable pullout resistance P1 of the anchor body based on the calculated side area A and volume V of the anchor body; The calculation formula of P1 is as follows: P1=f'×W F +C'×A+W L in: W F =V×γ×cos(α+β) IN L =V×γ×sinα (4) Calculate the number of anchors n based on the calculated allowable pullout resistance P1 of the anchor. The calculation formula for the number of anchors is as follows: n=KP / P1 n rounded up is the number of anchors, Where: K is the anchor body pull-out safety factor.

10. The multi-stage anchor tunnel type anchor according to claim 9, characterized in that: The value of K is 2.

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