Support structure for tunnel anchor under soft rock stratum condition and construction method thereof

Abstract

The application discloses a supporting structure for a tunnel anchor under soft rock stratum conditions, characterized in that the supporting structure comprises two rows of anti-slide pile assemblies and a bearing platform (2) arranged above the anti-slide pile assemblies; each anti-slide pile assembly comprises two anti-slide piles (1), and the two anti-slide piles (1) in one anti-slide pile assembly are arranged on the two sides of a tunnel anchor (a) respectively; the anti-slide pile assemblies and the bearing platform (2) are arranged in a mountain body and used for supporting the load of the mountain body. The application further provides a construction method of the supporting structure. The supporting structure provided by the application utilizes the system of "anti-slide pile + bearing platform", so that the load of the mountain body above the tunnel anchor chamber is clearly transmitted, the reinforcing effect is good, and the stability problem of the tunnel anchor excavated at the toe of a high and steep slope under complex geological conditions is solved.

Description

Technical Field

[0001] This application relates to the field of bridge construction technology, and in particular to a support structure for tunnel anchors in soft rock strata and its construction method. Background Technology

[0002] A suspension bridge is a bridge that uses tension-bearing cables as its main load-bearing component. It primarily consists of main cables, towers, anchorages, cables, and stiffening girders. Due to its large span capacity, it is a commonly used bridge structure in mountainous highway construction. The anchorage is a crucial part of a suspension bridge, responsible for securing the main cables and transferring the tension of the cables to the foundation. Suspension bridge anchorages are divided into self-anchored and ground-anchored types. Ground-anchored anchorages are further divided into gravity-type and tunnel-type. Tunnel-type anchorages (referred to as "tunnel anchors") can better integrate with the engineering geological conditions of the anchorage site, utilizing the interaction between the anchor body and the surrounding rock mass. They offer advantages such as small project scale, high cost-effectiveness, and minimal disturbance to the surrounding environment.

[0003] The installation of tunnel anchors requires consideration of the stability of the slope. The toe of the slope is typically a stress-concentrated area with poor stability. Currently, flexible structures such as anchor cables are commonly used to reinforce the toe. However, in some canyon areas with poor geological conditions, the upper part of the slope is composed of hard rock with well-developed joints and fissures, and relatively intact rock mass; while the lower part is composed of soft rock with extremely well-developed joints and fissures, and extremely fragmented rock mass, exhibiting a significant "hard upper, soft lower" geological characteristic. Using prestressed anchor cables for reinforcement in the soft rock area results in a long construction period, high construction quality risks, and poor deformation control, failing to achieve the goal of "stabilizing the toe" and posing certain safety risks to slope stability. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the first objective of this invention is to provide a support structure for tunnel anchors under soft rock strata conditions; the second objective of this invention is to provide a construction method for the above-mentioned support structure; the support structure provided in this application utilizes a "anti-slide pile + pile cap" system to support and reinforce the stability of the tunnel anchor opening, thus the load transmission mode of the mountain above the tunnel anchor chamber is clear and well-defined, the reinforcement effect is good, and the stability problem of tunnel anchors excavated at the toe of steep slopes under complex geological conditions is solved.

[0005] The technical solution provided by this invention is as follows:

[0006] A support structure for tunnel anchors in soft rock strata includes two rows of antislide pile assemblies and a pile cap located above the antislide pile assemblies.

[0007] Each anti-slide pile assembly includes two anti-slide piles, and the two anti-slide piles in one anti-slide pile assembly are respectively located on both sides of the tunnel anchor;

[0008] The anti-slide pile components and the pile cap are both located inside the mountain to support the mountain load.

[0009] Preferably, the length of the anti-slide pile in the anti-slide pile assembly near the inner side of the mountain is longer than the length of the anti-slide pile in the anti-slide pile assembly near the outer side of the mountain.

[0010] Preferably, the two anti-slide piles in an anti-slide pile assembly are of equal length.

[0011] Preferably, the lower end of the anti-slide pile is buried in the mountain, and the top of the anti-slide pile is higher than the top of the tunnel anchor;

[0012] The pier is located within the first-level slope.

[0013] The construction method for the support structure described in any of the above-mentioned items includes the following steps:

[0014] S1. One anti-slide pile in each row of anti-slide pile components is installed simultaneously, and the anti-slide piles installed simultaneously are located at diagonal positions;

[0015] S2. Install another anti-slide pile in each row of anti-slide pile components;

[0016] S3. Construct the foundation;

[0017] S4. Excavate the tunnel anchor chamber and carry out the tunnel anchor construction.

[0018] Preferably, after step S4, a backfilling and counter-pressure step is also included.

[0019] The support structure provided in this application utilizes a "anti-slide pile + pile cap" system to support and reinforce the stability of the tunnel anchorage. Two anti-slide piles are distributed on each side of the tunnel anchorage, and a pile cap is set above the four anti-slide piles. The load of the mountain and slope above is transferred to the pile cap, and then transferred to the bedrock below through multiple anti-slide piles. The force transmission mode is clear and well-defined, the reinforcement effect is good and stable, and the overall stability of the slope is ensured. This creates favorable conditions for the smooth excavation of the tunnel anchorage and avoids the safety risks of tunnel anchorage excavation caused by the failure of anchor cables in soft rock areas. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a top view of the support structure in an embodiment of the present invention;

[0022] Figure 2 for Figure 1 A magnified view of a portion of the image;

[0023] Figure 3 This is a side view of the support structure in an embodiment of the present invention; where b is bridge abutment No. 0;

[0024] Figure 4 for Figure 3 A magnified view of a portion of the image;

[0025] Attached diagram labels: 1-Anti-slide pile; 2-Pile cap; a-Tunnel anchor. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0028] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0030] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0031] As shown in the figure, this embodiment of the invention provides a support structure for tunnel anchors under soft rock strata conditions, including two rows of anti-slide pile components and a pile cap 2 disposed above the anti-slide pile components;

[0032] Each anti-slide pile assembly includes two anti-slide piles 1, and the two anti-slide piles 1 in one anti-slide pile assembly are respectively located on both sides of the tunnel anchor a;

[0033] Both the anti-slide pile assembly and the pile cap 2 are located inside the mountain to support the mountain load.

[0034] To address the issues of stress concentration and poor stability at the toe of a slope, particularly the tendency for anchor cable reinforcement to fail in "hard upper and soft lower" strata, this application provides a support structure for a tunnel anchor, comprising two rows of anti-slide pile assemblies and a foundation 2 located above the anti-slide pile assemblies. Each anti-slide pile assembly includes two anti-slide piles 1, with the two anti-slide piles 1 within an anti-slide pile assembly located on either side of the tunnel anchor a. Both the anti-slide pile assemblies and the foundation 2 are located within the mountain to support the mountain load.

[0035] The support structure provided in this application utilizes a "anti-slide pile + pile cap" system to support and reinforce the stability of the tunnel anchor entrance. Two anti-slide piles 1 are distributed on each side of the tunnel anchor chamber, and a pile cap 2 is set above the four anti-slide piles 1. The load of the mountain and slope above is transferred to the pile cap 2, and then transferred to the bedrock below through multiple anti-slide piles 1. The force transmission mode is clear and well-defined, the reinforcement effect is good and stable, and the overall stability of the slope is ensured. This creates favorable conditions for the smooth excavation of the tunnel anchor and avoids the safety risks of tunnel anchor excavation caused by the failure of anchor cables in soft rock areas.

[0036] In this application, the two anti-slide piles 1 of an anti-slide pile assembly are respectively located on both sides of the tunnel anchor a, which means that the two anti-slide piles 1 are located on both sides of the center line of the tunnel anchor a, respectively, to support the mountain above the tunnel anchor a chamber.

[0037] Preferably, the length of the anti-slide pile 1 in the anti-slide pile assembly near the inner side of the mountain is longer than the length of the anti-slide pile 1 in the anti-slide pile assembly near the outer side of the mountain.

[0038] Preferably, the two antislide piles 1 in an antislide pile assembly are of equal length.

[0039] The length of the anti-slide pile 1 in the anti-slide pile assembly closer to the inside of the mountain is preferably longer than the length of the anti-slide pile 1 in the anti-slide pile assembly closer to the outside of the mountain.

[0040] The tunnel anchor a chamber slopes downwards from the outside of the mountain towards the inside. As the depth of the tunnel anchor a chamber increases, the length of the anti-slide pile 1 at the corresponding location also increases to ensure the effectiveness of the pile foundation cap, that is, to ensure the stability and support effect of the anti-slide pile 1 and the cap 2. The increase in the length of the anti-slide pile 1 is due to the increase in the embedment depth. The top surface height of the anti-slide pile 1 at different locations remains unchanged, and they all connect with the bottom surface of the cap 2.

[0041] Preferably, the two anti-slide piles 1 in an anti-slide pile assembly are of equal length. If the geological conditions on both sides of the tunnel anchor a are the same, then the anti-slide piles in the same row must be of the same length.

[0042] Preferably, the lower end of the anti-slide pile 1 is buried in the mountain, and the top of the anti-slide pile 1 is higher than the top of the tunnel anchor a;

[0043] The foundation 2 is located within the first-level slope.

[0044] Ideally, the lower end of anti-slide pile 1 should be embedded within the mountain, and the top of anti-slide pile 1 should be higher than the top of tunnel anchor a, while the pile cap 2 should be located within the first-level slope. Therefore, after the construction of anti-slide pile 1 and pile cap 2 is completed, the excavation of the tunnel anchor a chamber will not interfere with the support structure.

[0045] The dimensions of anti-slide pile 1 and pile cap 2 are related to the weathering limit, rock mass strength, and excavation depth of the tunnel anchor, and need to be determined based on on-site measurement data and construction requirements.

[0046] The construction method for the support structure described in any of the above-mentioned items includes the following steps:

[0047] S1. One anti-slide pile 1 in each row of anti-slide pile assembly is installed simultaneously, and the anti-slide piles 1 installed simultaneously are located at diagonal positions;

[0048] S2. Construct another anti-slide pile 1 in each row of anti-slide pile components;

[0049] S3. Construct foundation 2;

[0050] S4. Excavate the chamber for the tunnel anchor and carry out the construction of tunnel anchor a.

[0051] This application also provides a construction method for the above-mentioned support structure. Specifically, one anti-slide pile 1 in each row of anti-slide pile assembly is constructed simultaneously, and the anti-slide pile 1 constructed simultaneously is located at a diagonal position; then another anti-slide pile 1 in each row of anti-slide pile assembly is constructed; then the pile cap 2 is constructed; finally, the tunnel anchor chamber is excavated, and the tunnel anchor a is constructed.

[0052] Preferably, after step S4, a backfilling and counter-pressure step is also included.

[0053] As is known in the art, after tunnel construction is completed, a counter-pressure is applied to the toe of the entire slope. The counter-pressure slope ratio and the design slope ratio of the side slope are determined according to actual needs. For example, the design slope ratio of the side slope is 1:0.3, and the design counter-pressure slope ratio is 1:2. According to the slope design of the side slope, after the foundation 2 is built, a backfilling step may also be included.

[0054] Example 1

[0055] A support structure for tunnel anchors under soft rock strata conditions in a certain area includes two rows of anti-slide pile components and a pile cap 2 located above the anti-slide pile components.

[0056] Each anti-slide pile assembly includes two anti-slide piles 1. The anti-slide piles in the first row of the assembly are named anti-slide pile C1 and anti-slide pile C2, respectively. The anti-slide piles in the second row of the assembly are named anti-slide pile D1 and anti-slide pile D2, respectively. C1 and C2, and D1 and D2 are located on both sides of the tunnel anchor a, with C1 and C2 closer to the outer side of the mountain and each having a length of 32m. D1 and D2 are closer to the inner side of the mountain and each having a length of 37m. The horizontal dimensions of all anti-slide piles are 2x3m.

[0057] The lower ends of all anti-slide piles 1 are buried in the mountain, and the top of the anti-slide piles 1 is higher than the top of the tunnel anchor a; the pile cap 2 is located in the first-level slope, with a length of 14.8m, a width of 9.7m, and a height of 4.5m.

[0058] The above-mentioned construction method for the support structure includes the following steps:

[0059] S1. First, construct anti-slide piles C1 and D2, which are located diagonally.

[0060] S2. After anti-slide piles C1 and D2 are completed, anti-slide piles C2 and D1 will be constructed.

[0061] S3. Construct pile cap 2 on the top surface of the four anti-slide piles; backfill with counterweight.

[0062] S4. Excavate the chamber for the tunnel anchor and carry out the construction of tunnel anchor a.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A construction method for a support structure for tunnel anchors in soft rock strata, characterized in that, The support structure includes two rows of anti-slide pile components and a pile cap (2) located above the anti-slide pile components. Each anti-slide pile assembly includes two anti-slide piles (1), and the two anti-slide piles (1) in one anti-slide pile assembly are respectively located on both sides of the tunnel anchor (a); The anti-slide pile assembly and the pile cap (2) are both located inside the mountain to support the mountain load; The above-mentioned construction method for the support structure includes the following steps: S1. One anti-slide pile (1) in each row of anti-slide pile assembly is installed simultaneously, and the anti-slide piles (1) installed simultaneously are located at diagonal positions; S2. Construct another anti-slide pile (1) in each row of anti-slide pile components; S3. Construct the foundation (2); S4. Excavate the tunnel anchor chamber and carry out the construction of tunnel anchor (a).

2. The construction method for the support structure of tunnel anchors under soft rock strata conditions according to claim 1, characterized in that, The length of the anti-slide pile (1) in the anti-slide pile assembly near the inner side of the mountain is longer than the length of the anti-slide pile (1) in the anti-slide pile assembly near the outer side of the mountain.

3. The construction method for the support structure of tunnel anchors under soft rock strata conditions according to claim 2, characterized in that, Two antislide piles (1) in an antislide pile assembly are of equal length.

4. The construction method for the support structure of tunnel anchors under soft rock strata conditions according to any one of claims 1-3, characterized in that, The lower end of the anti-slide pile (1) is buried in the mountain, and the top of the anti-slide pile (1) is higher than the top of the tunnel anchor (a); The pier (2) is located within the first-level slope.

5. The construction method of the support structure according to claim 1, characterized in that, After step S4, the process also includes a backfilling and counter-pressure step.

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