Pressure dispersion type tunnel anchorage and construction method

Abstract

The invention provides a pressure dispersion type tunnel anchorage and a construction method, and the pressure dispersion type tunnel anchorage is located in an underground space of a stratum below the earth surface and comprises a cavern system, a cable structure and an anchoring structure. The cavern system is stored in a stratum below the earth surface and is used for providing a building space for the cable structure and the anchoring structure; the cable structure comprises a main cable, a splay cable saddle and cable strands, the main cable is a main component for transmitting the load of the suspension bridge to the anchorage, and the splay cable saddle is used for dispersing the main cable into a plurality of cable strands; the anchoring structure comprises a front anchorage device, a steel beam, a protection pipe, an anchor body and a rear anchorage device, a plurality of wedge-shaped cavities are formed in the middle-rear portion of the anchor body, a plurality of rear anchor faces are formed, the steel beam is anchored to the different rear anchor faces of the anchor body, loads are transmitted to the anchor body in a pressure dispersion mode, and the front anchorage device and the rear anchorage device clamp and fix the two ends of the steel beam respectively. Loads are dispersed and applied to different parts of the anchor body, so that the stress distribution of the anchor body is more uniform, and the construction cost is effectively reduced by reducing the size of the anchor body.

Description

Technical Field

[0001] The invention relates to the technical field of bridge engineering, and in particular to a pressure-dispersed tunnel anchor and a construction method thereof. Background Art

[0002] Tunnel anchor is an important ground anchor structure for anchoring the main cable of suspension bridge. The construction process of tunnel anchor is: first, excavate the anchor hole in the rock layer below the surface, then pour concrete to fill the anchor hole to form the anchor body, and finally use the anchor body to bear the transferred bridge load to achieve the anchoring effect. The existing tunnel anchors mostly use solid wedge-shaped anchor bodies, with one front anchor surface and one rear anchor surface. When the tunnel anchor bears the load in a compressive manner, the anchor structure adopts a prestressed non-bonded anchor system. There is no bond between the prestressed steel bundle and the protective pipe. The main cable is dispersed into strands and connected to the steel bundle to transfer the load to the rear anchor surface, and the anchor is applied with thrust through the anchor. The load of this pressure-type tunnel anchor is concentrated on one rear anchor surface of the anchor body, which has two obvious defects. First, the stress of the anchor surface where the anchor body bears the load is concentrated, and the stability is reduced; second, the amount of concrete used in the anchor body is large, the construction is difficult and the cost is high. Summary of the invention

[0003] In view of the defects of the prior art, the present invention provides a pressure-dispersed tunnel anchor and construction method. After the main cable of the bridge is dispersed into strands, it reaches a front anchor surface of the anchor body and is connected to the prestressed steel bundle of the anchor structure to transfer the load. The prestressed steel bundle passes through multiple rear anchor surfaces of the anchor body for anchoring, and the load is transferred to the anchor body in a pressure-dispersed manner. The present invention disperses the load applied to different parts of the anchor body, making the stress distribution of the anchor body more uniform, reducing the volume of the anchor body by more than 60%, and effectively reducing the pouring volume of the anchor body concrete.

[0004] A pressure-dispersed tunnel anchor is located in an underground space of a stratum below the surface of the earth, and the pressure-dispersed tunnel anchor comprises a cavern system, a cable structure and an anchor structure;

[0005] The cave system exists in the stratum below the ground surface and is used to provide construction space for cable structures and anchor structures;

[0006] The cable structure includes a main cable, a loose cable saddle and cable strands, wherein the main cable is a main component for transmitting the load of the suspension bridge to the anchor, and the loose cable saddle is used to disperse the main cable into multiple cable strands;

[0007] The anchoring structure includes a front anchor, a steel bundle, a protective tube, an anchor body and a rear anchor. A plurality of wedge-shaped holes are provided in the middle and rear part of the anchor body to form a plurality of rear anchor surfaces. The steel bundle is anchored to different rear anchor surfaces of the anchor body to transfer the load to the anchor body in a pressure-dispersed manner. The front anchor is located on the front anchor surface of the anchor body and is used to clamp and fix one end of the steel bundle. The rear anchor is located on the rear anchor surface of the anchor body and is used to clamp and fix the other end of the steel bundle.

[0008] Furthermore, the cavern system includes an inclined tunnel, a front anchor chamber, an anchor hole and a rear anchor chamber which are connected in sequence; the inclined tunnel is located at the head of the cavern system, connecting the ground to the front anchor chamber, the inclined tunnel is parallel to the axis of the main cable, and provides space for the main cable to pass through; the front anchor chamber is a passage from the connecting tunnel to the anchor hole, providing space for the cable strands to spread out, and a construction space for the anchoring structure; the anchor hole is a passage connecting the front anchor chamber to the rear anchor chamber, and is the storage space of the anchoring structure, and the shape of the anchor hole determines the external shape of the anchor body; the rear anchor chamber is located at the tail of the cavern system, providing a construction space for the anchoring structure and a maintenance space for the long-term operation stage.

[0009] Furthermore, the loose cable saddle is located at the front part of the front anchor chamber.

[0010] Furthermore, the cable strands are divided into a first cable strand, a second cable strand and a third cable strand, the first cable strand is a cable strand of an inner circle, the second cable strand is a cable strand of a middle circle, and the third cable strand is a cable strand of an outer circle, and the starting points of the first cable strand, the second cable strand and the third cable strand are loose cable saddles, and the end points are a front anchor surface of the anchor body.

[0011] Furthermore, the steel bundle is divided into a first steel bundle, a second steel bundle and a third steel bundle; the first steel bundle is connected to the first cable strand at the front anchor surface of the anchor body and has the shortest length; the second steel bundle is connected to the second cable strand at the front anchor surface of the anchor body and has a middle length; the third steel bundle is connected to the third cable strand at the front anchor surface of the anchor body and has the longest length; the anchor body has three rear anchor surfaces, with two rear anchor surfaces inside it as boundaries, and is divided into a first anchor body, a second anchor body and a third anchor body; the first steel bundle passes through the first anchor body and reaches its rear anchor surface, the second steel bundle passes through the second anchor body and reaches its rear anchor surface, and the third steel bundle passes through the third anchor body and reaches its rear anchor surface.

[0012] Furthermore, the anchoring structure also includes a protective pipe, in which the steel bundle is buried, and the protective pipe is made of steel material.

[0013] Furthermore, the steel bundle is made of high-strength steel strands.

[0014] A method for constructing the pressure-dispersed tunnel anchorage as described above comprises the following steps:

[0015] Step S1: Cavern system construction and construction:

[0016] From the surface, dig and support the inclined tunnel, front anchor chamber, anchor hole and rear anchor chamber in sequence to form a connected and stable underground space;

[0017] Step S2: anchoring structure construction and construction:

[0018] Step S21, casting the anchor body and accessory parts, using steel brackets to fix all protective pipes, anchor pads of all front anchors and anchor pads of all rear anchors, using templates to form the outer contour of the anchor body, integrally casting concrete to form the anchor body, and curing until the concrete setting period is over, and the anchor body is divided into the first anchor body, the second anchor body and the third anchor body;

[0019] Step S22, installation of the steel bundle and the front and rear anchors: firstly, the steel bundle is passed through the front anchor, the protective pipe and the rear anchor in sequence, then the anchor rings of the front anchor and the rear anchor are installed, then the steel bundle is tightened by the tensioning equipment, and finally, the clamp is used to lock it, and all the steel bundles are divided into the first steel bundle, the second steel bundle and the third steel bundle;

[0020] Step S3: Cable structure construction and construction:

[0021] Step S31, transport the loose cable saddle to the front anchor chamber and install and fix it at the bottom of the cave;

[0022] Step S32, the main cable enters the cave from the surface through the inclined hole, and is separated into multiple cable strands at the cable saddle, and all the cable strands are divided into the first cable strand, the second cable strand and the third cable strand;

[0023] Step S33, all the cable strands are sequentially connected to all the steel bundles to transfer the load. Specifically, the first cable strand is connected to the first steel bundle, the second cable strand is connected to the second steel bundle, and the third cable strand is connected to the third steel bundle;

[0024] Step S4: Anti-corrosion materials are applied to the outer surface of the concrete and the exposed anchors and steel strands, and the space inside the anchor body is used for maintenance during the long-term operation stage.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The tunnel anchor provided by the present invention has a traditional wedge-shaped anchor body, retaining the classic cave system layout and anchor body shape, and the anchor has reliable stability and load-bearing capacity.

[0027] 2. The anchor body of the present invention is provided with a wedge-shaped cavity inside, and the volume of the anchor body is reduced by more than half without changing the bearing capacity of the anchor body, thereby effectively reducing the project cost.

[0028] 3. The anchor body of the present invention is provided with a plurality of rear anchor surfaces to share the load transmitted by the main cable. This design makes the stress distribution of the anchor body more uniform, significantly optimizes and improves the bearing conditions of the anchor body, and improves the stability and reliability of the anchor body bearing.

[0029] 4. The wedge-shaped cavity inside the anchor body of the present invention can provide space for maintenance during long-term operation, which is beneficial to the safety of personnel and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a structural arrangement diagram of a vertical section of a pressure-dispersed tunnel anchorage according to an embodiment of the present invention;

[0031] Figure 2 It is a layout diagram of an oblique cross section of a cavern system in an embodiment of the present invention;

[0032] Figure 3 It is an oblique cross-sectional layout diagram of the cable structure and the anchoring structure in an embodiment of the present invention;

[0033] Figure 4 The shape of the front anchor surface and the distribution diagram of the front anchor in the embodiment of the present invention;

[0034] Figure 5 The shape of the rear anchor surface and the distribution diagram of the rear anchor in the embodiment of the present invention;

[0035] Figure 6 It is a structural diagram of different cross-sections of the anchor body in an embodiment of the present invention;

[0036] Figure 7 It is a schematic diagram of the installation of the steel bundle and the protective tube in the anchor body in an embodiment of the present invention;

[0037] Figure 8 1 is a comparison diagram of the external pressure of the anchor body (a) in the embodiment of the present invention and the traditional anchor body (b). DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the 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 creative work are within the scope of protection of the present invention.

[0039] See also Figure 1-7 The embodiment of the present invention provides a pressure-dispersed tunnel anchor, which is located in an underground space of a stratum 2 below the surface 1, and includes a cavern system 3, a cable structure 4 and an anchor structure 5, such as Figure 1 shown.

[0040] The cave system 3 is located in the stratum 2 below the ground surface 1, and includes an inclined cave 31, a front anchor chamber 32, an anchor cave 33 and a rear anchor chamber 34, and is used to provide a construction space for the cable structure 4 and the anchor structure 5. Figure 1 and Figure 2 shown.

[0041] The inclined hole 31 is located at the head of the cave system 3, and is a passage connecting the ground surface 1 to the front anchor chamber 32. The inclined hole 31 is parallel to the axis of the main cable 41, and provides a space for the main cable 41 to pass through.

[0042] The front anchor chamber 32 is a passage connecting the hole 31 to the anchor hole 33 , providing a space for the cable strands 43 to spread out and a space for constructing the anchoring structure 5 .

[0043] The anchor hole 33 is a passage connecting the front anchor chamber 32 to the rear anchor chamber 34 , and is a storage space of the anchor structure 5 . The shape of the anchor hole 33 determines the external shape of the anchor body 54 .

[0044] The rear anchor chamber 34 is located at the tail end of the cavern system 3, providing a construction space for the anchor structure 5 and a maintenance space during the long-term operation stage.

[0045] The cable structure 4 transfers and introduces the suspension bridge load into the underground space, passes through the inclined hole 31 to the front anchor chamber 32, and then disperses it for anchoring. The cable structure 4 includes a main cable 41, a loose cable saddle 42 and a cable strand 43. Figure 1 and Figure 3 shown.

[0046] The main cable 41 is a main component for transmitting the load of the suspension bridge to the anchor. The main cable 41 enters the underground space from the surface 1 through the inclined tunnel 31. The main cable 41 is made of high-strength steel strands.

[0047] The dispersed cable saddle 42 is located at the front of the front anchor chamber 32 , and disperses the main cable 41 into a plurality of cable strands 43 so as to be separately anchored and transfer the load to the anchoring structure 5 .

[0048] The strands 43 are directly spread out from the main cable 41, and the strands 43 are connected to the steel bundle 52 to transfer the load. The strands 43 are made of the same steel strands as the main cable 41. The strands 43 are divided into a first strand 43a, a second strand 43b, and a third strand 43c. The first strand 43a is a strand of the inner circle, the second strand 43b is a strand of the middle circle, and the third strand 43c is a strand of the outer circle. The starting point of the first strand 43a, the second strand 43b, and the third strand 43c is the spread saddle 42, and the end point is a front anchor surface of the anchor body 54.

[0049] The anchor structure 5 is made by pouring concrete and burying equipment in the anchor hole 33, with the front anchor chamber 32 and the rear anchor chamber 34 as the construction space. The anchor structure 5 includes a front anchor 51, a steel bundle 52, a protective pipe 53, an anchor body 54 and a rear anchor 55. Figure 1 and Figure 3 shown.

[0050] The front anchor 51 is located at the front anchor surface of the anchor body 54 and is used to clamp and fix one end of the steel bundle 52. The front anchor 51 is composed of an anchor plate, an anchor ring and a clip, wherein the anchor plate is buried in the anchor body 54. There is only one front anchor surface of the anchor body 54, so all the front anchors 51 are located on the same plane. Figure 4 shown.

[0051] The steel bundle 52 is a component for transferring the load of the cable strand 43 to the anchor body 54. The steel bundle 52 passes through the anchor body 54 from the front anchor surface to the rear anchor surface. Both ends of the steel bundle 52 are locked with anchors. The steel bundle 52 is made of high-strength steel strands and buried in the protective tube 53. Figure 7 shown.

[0052] like Figure 6 As shown, the steel bundle 52 is divided into a first steel bundle 52a, a second steel bundle 52b and a third steel bundle 52c.

[0053] The first steel bundle 52a is connected to the first cable strand 43a at the front anchor surface of the anchor body 54 and has the shortest length.

[0054] The second steel bundle 52b is connected to the second cable strand 43b at the front anchor surface of the anchor body 54 and has a middle length.

[0055] The third steel bundle 52c is connected to the third cable strand 43c at the front anchor surface of the anchor body 54 and has the longest length.

[0056] The protective tube 53 is a component for protecting the steel bundle 52 , and the protective tube 53 is made of steel material.

[0057] The anchor body 54 is a base for installing and fixing the metal parts of the anchor structure 5, and is cast in place in the anchor hole 33 with concrete. The outer contour of the anchor body 54 is wedge-shaped, and two wedge-shaped holes of different sizes and interpenetrating with each other are provided in the middle and rear part, and the side and bottom surfaces of the holes are respectively parallel to the side and bottom surfaces of the anchor body 54. The anchor body 54 has three rear anchor surfaces, and the two rear anchor surfaces inside it are bounded, and can be divided into a first anchor body 54a, a second anchor body 54b and a third anchor body 54c.

[0058] The first steel strand 52a passes through the first anchor body 54a and reaches the rear anchor surface thereof.

[0059] The second steel strand 52b passes through the second anchor body 54b and reaches the rear anchor surface thereof.

[0060] The third steel strand 52c passes through the third anchor body 54c and reaches the rear anchor surface thereof.

[0061] The rear anchor 55 is located at the rear anchor surface of the anchor body 54, clamping and fixing the other end of the steel bundle 52. The rear anchor 55 is composed of an anchor pad, an anchor ring and a clip, wherein the anchor pad is buried in the anchor body 54, such as Figure 5 shown.

[0062] The embodiment of the present invention further provides a method for constructing a pressure-dispersed tunnel anchor, comprising the following steps:

[0063] Step S1, cavern system 3 construction and construction.

[0064] From the ground surface 1, an inclined tunnel 31, a front anchor chamber 32, an anchor tunnel 33 and a rear anchor chamber 34 are excavated and supported in sequence to form a connected and stable underground space.

[0065] Step S2: constructing and constructing the anchoring structure 5.

[0066] Step S21, casting of anchor body 54 and accessory parts. All protective pipes 53, anchor pads of all front anchors 51 and anchor pads of all rear anchors 55 are fixed by steel brackets, the outer contour of anchor body 54 is made by template, concrete of anchor body 54 is cast in one piece, and curing is performed until the concrete setting period ends. The segmented anchor body 54 is composed of first anchor body 54a, second anchor body 54b and third anchor body 54c.

[0067] Step S22, installation of the steel bundle 52 and the front and rear anchors. Taking one steel bundle 52 as an example, firstly, the steel bundle 52 is passed through the front anchor 51, the protective tube 53 and the rear anchor 55 in sequence, then the anchor rings of the front anchor 51 and the rear anchor 55 are installed, then the steel bundle 52 is tightened by the tensioning equipment, and finally, the clamp is used to lock it. All the steel bundles 52 are divided into the first steel bundle 52a, the second steel bundle 52b and the third steel bundle 52c.

[0068] Step S3: cable structure 4 is constructed and constructed.

[0069] Step S31, transport the loose rope saddle 42 to the front anchor chamber 32, and install and fix it at the bottom of the cave.

[0070] Step S32: the main cable 41 enters the cave from the surface through the inclined hole 31, and is separated into a plurality of cable strands 43 at the cable saddle 42. All the cable strands 43 are divided into a first cable strand 43a, a second cable strand 43b and a third cable strand 43c.

[0071] Step S33: All the strands 43 are sequentially connected to all the steel bundles 52 to transfer the load. Specifically, the first strand 43a is connected to the first steel bundle 52a, the second strand 43b is connected to the second steel bundle 52b, and the third strand 43c is connected to the third steel bundle 52c.

[0072] Step S4: Anti-corrosion materials are applied to the outer surface of the concrete and the exposed anchors and steel strands, and the space inside the anchor body 54 is used for maintenance during the long-term operation stage.

[0073] The shape of the rear hollow space in the anchor body of the present invention is a wedge shape similar to the shape of the anchor body, and other shapes such as a cylinder or a cone may also be used.

[0074] The number of wedge-shaped cavities in the rear portion of the anchor body of the present invention can be adjusted. The present invention is described using 3 as an example, but the number of cavities can also be 2, 4 or more. The pressure dispersion effect can be achieved by adjusting the number of anchor surfaces at the rear of the anchor body, the number of cable strands and the number of steel bundle sections.

[0075] The load transfer component of the anchor structure of the present invention is a prestressed steel bundle, and its external pressure is dispersed compared with the traditional anchor body, such as Figure 8 Based on the anchor body shape of the present invention, different section load transfer components respectively use prestressed tendons or non-prestressed tendons to form a tension-compression composite tunnel anchor.

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A pressure-dispersed tunnel anchorage located in an underground space of a stratum below the surface, characterized in that: The pressure-dispersed tunnel anchorage includes a cavern system, a cable structure and an anchoring structure; The cave system exists in the stratum below the ground surface and is used to provide construction space for cable structures and anchor structures; The cable structure includes a main cable, a loose cable saddle and cable strands, wherein the main cable is a main component for transmitting the load of the suspension bridge to the anchor, and the loose cable saddle is used to disperse the main cable into multiple cable strands; The anchoring structure includes a front anchor, a steel bundle, a protective tube, an anchor body and a rear anchor. A plurality of wedge-shaped holes are provided in the middle and rear part of the anchor body to form a plurality of rear anchor surfaces. The steel bundle is anchored to different rear anchor surfaces of the anchor body to transfer the load to the anchor body in a pressure-dispersed manner. The front anchor is located on the front anchor surface of the anchor body and is used to clamp and fix one end of the steel bundle. The rear anchor is located on the rear anchor surface of the anchor body and is used to clamp and fix the other end of the steel bundle.

2. The pressure-dispersed tunnel anchorage according to claim 1, characterized in that: The cavern system includes an inclined tunnel, a front anchor chamber, an anchor hole and a rear anchor chamber which are connected in sequence; the inclined tunnel is located at the head of the cavern system, connecting the ground surface to the front anchor chamber, and the inclined tunnel is parallel to the main cable axis, providing space for the main cable to pass through; the front anchor chamber is a passage from the connecting tunnel to the anchor hole, providing space for the cable strands to spread out, as well as construction space for the anchor structure; the anchor hole is a passage connecting the front anchor chamber to the rear anchor chamber, and is the storage space of the anchor structure, and the shape of the anchor hole determines the external shape of the anchor body; the rear anchor chamber is located at the tail of the cavern system, providing construction space for the anchor structure and maintenance space during the long-term operation stage.

3. The pressure-dispersed tunnel anchorage according to claim 2, characterized in that: The loose cable saddle is located at the front part of the front anchor chamber.

4. The pressure-dispersed tunnel anchorage according to claim 1, characterized in that: The cable strands are divided into a first cable strand, a second cable strand and a third cable strand, the first cable strand is a cable strand of an inner circle, the second cable strand is a cable strand of a middle circle, and the third cable strand is a cable strand of an outer circle. The starting points of the first cable strand, the second cable strand and the third cable strand are loose cable saddles, and the end points are a front anchor surface of the anchor body.

5. The pressure-dispersed tunnel anchorage according to claim 4, characterized in that: The steel bundles are divided into the first steel bundle, the second steel bundle and the third steel bundle; the first steel bundle is connected to the first cable strand at the front anchor surface of the anchor body and has the shortest length; the second steel bundle is connected to the second cable strand at the front anchor surface of the anchor body and has a middle length; the third steel bundle is connected to the third cable strand at the front anchor surface of the anchor body and has the longest length; the anchor body has three rear anchor surfaces, with the two rear anchor surfaces inside it as boundaries, and is divided into the first anchor body, the second anchor body and the third anchor body; the first steel bundle passes through the first anchor body and reaches its rear anchor surface, the second steel bundle passes through the second anchor body and reaches its rear anchor surface, and the third steel bundle passes through the third anchor body and reaches its rear anchor surface.

6. The pressure-dispersed tunnel anchorage according to claim 1, characterized in that: The anchoring structure also includes a protective pipe, in which the steel bundle is buried, and the protective pipe is made of steel material.

7. The pressure-dispersed tunnel anchorage according to claim 6, characterized in that: The steel bundle is made of high-strength steel strands.

8. A method for constructing a pressure-dispersed tunnel anchorage according to any one of claims 1 to 7, characterized in that: The steps include: Step S1: Cavern system construction and construction: From the surface, dig and support the inclined tunnel, front anchor chamber, anchor hole and rear anchor chamber in sequence to form a connected and stable underground space; Step S2: anchoring structure construction and construction: Step S21, casting the anchor body and accessory parts, using steel brackets to fix all protective pipes, anchor pads of all front anchors and anchor pads of all rear anchors, using templates to form the outer contour of the anchor body, integrally casting concrete to form the anchor body, and curing until the concrete setting period is over, and the anchor body is divided into the first anchor body, the second anchor body and the third anchor body; Step S22, installation of the steel bundle and the front and rear anchors: firstly, the steel bundle is passed through the front anchor, the protective pipe and the rear anchor in sequence, then the anchor rings of the front anchor and the rear anchor are installed, then the steel bundle is tightened by the tensioning equipment, and finally, the clamp is used to lock it, and all the steel bundles are divided into the first steel bundle, the second steel bundle and the third steel bundle; Step S3: Cable structure construction and construction: Step S31, transport the loose cable saddle to the front anchor chamber and install and fix it at the bottom of the cave; Step S32, the main cable enters the cave from the surface through the inclined hole, and is separated into multiple cable strands at the cable saddle, and all the cable strands are divided into the first cable strand, the second cable strand and the third cable strand; Step S33, all the cable strands are sequentially connected to all the steel bundles to transfer the load. Specifically, the first cable strand is connected to the first steel bundle, the second cable strand is connected to the second steel bundle, and the third cable strand is connected to the third steel bundle; Step S4: Anti-corrosion materials are applied to the outer surface of the concrete and the exposed anchors and steel strands, and the space inside the anchor body is used for maintenance during the long-term operation stage.

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