Prestressed anchor rod structure of high-ground-stress soft rock large-deformation tunnel

Abstract

The utility model provides a high crustal stress soft rock large deformation tunnel pre-stressed anchor rod structure which comprises a pre-stressed anchor rod, a grouting pipe is fixed on one side of the pre-stressed anchor rod, a slurry return pipe is fixed on the other side of the pre-stressed anchor rod, and the pre-stressed anchor rod comprises a first anchoring section and a second anchoring section. A grout stopping ring is arranged at the joint of the first anchoring section and the second anchoring section, a lathing thread is arranged at the end, away from the grout stopping ring, of the second anchoring section, and by arranging the first anchoring section, the grout stopping ring and the lathing thread, pre-tightening force can be conveniently applied to the pre-stressed anchor rod after installation, so that the friction effect between different rock stratums can be increased, surrounding rock within the anchoring range is clamped, and the anchoring effect is improved. A bearing structure is formed, and the stability of tunnel surrounding rock is improved; the single pre-stressed anchor rods are reasonably distributed in the surrounding rock, stressed areas are overlapped and interact with one another, the surrounding rock within a certain range is reinforced, and deformation and development of plastic zones are effectively reduced; and grouting and secondary grouting can be carried out, so that the pre-stressed anchor rod is more stable, and the anchoring survival rate is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of tunnel support, in particular to a prestressed anchor rod structure for a high-in-situ stress soft rock large-deformation tunnel. Background Art

[0002] Anchor rods are rod-shaped components that mainly bear tensile forces. Anchor rods use drilling and grouting technology to fix the rod body in deep stable strata, which stabilizes the reinforced object and limits the deformation of the object. Prestressed anchor rods are an important type of anchor support. After the anchor rods are installed, prestress is actively applied to the anchor rods to make them tensile, thereby limiting the deformation of the rock or soil, improving the mechanical properties and stress state of the rock or soil, and enhancing its overall safety and stability. It has the advantages of safety, high efficiency, and fast construction. It has been widely used in underground projects, slope projects, deep foundation pit projects, and bridge projects.

[0003] When prestressed anchors are installed in high-ground stress soft rock large deformation tunnels, internal deformation of the surrounding rock is likely to occur, resulting in difficulties in drilling inclined holes and deep holes at the arch waist or arch top, difficulty in inserting anchors, and low anchor survival rate. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiencies of the above-mentioned prior art and provide a prestressed anchor rod structure for a high-in-situ stress soft rock large deformation tunnel, which can solve the problem of low survival rate of anchor rods in high-in-situ stress soft rock large deformation tunnels.

[0005] To this end, the utility model adopts the following technical solutions:

[0006] A prestressed anchor rod structure for a high-ground stress soft rock large deformation tunnel comprises a prestressed anchor rod, a grouting pipe is fixed to one side of the prestressed anchor rod, a grouting pipe is fixed to the other side of the prestressed anchor rod, the prestressed anchor rod comprises a first anchoring section and a second anchoring section, a grouting stop ring is provided at the junction of the first anchoring section and the second anchoring section, and a thread is provided at one end of the second anchoring section away from the grouting stop ring.

[0007] On the basis of adopting the above technical solutions, the present invention can also adopt the following further technical solutions, or use these further technical solutions in combination:

[0008] The length of the first anchoring section is one sixth of the length of the prestressed anchor rod.

[0009] The grouting pipe is fixedly connected to the second anchoring section. An opening is provided on one side of the grouting pipe. The distance between the opening and the stop ring is one fifteenth of the length of the second anchoring section.

[0010] The length of the thread is 10 cm.

[0011] The return slurry pipe is fixed to one end of the second anchoring section, and the overlapping length of the return slurry pipe and the second anchoring section is 40 cm.

[0012] A plurality of fixed connectors are arranged outside the grouting pipe and the return grouting pipe, and the fixed connectors fixedly connect the grouting pipe, the return grouting pipe and the prestressed anchor rod.

[0013] The fixed connection piece is an adhesive tape used for binding.

[0014] The prestressed anchor rod is a threaded steel bar with a length of 9m and a diameter of 32mm.

[0015] The grouting pipe and the return grouting pipe are both PVC pipes with an inner diameter of 14 mm and an outer diameter of 16 mm.

[0016] The slurry-stopping ring is a rubber ring or hemp thread.

[0017] Compared with the prior art, the utility model has the following advantages and beneficial effects: by arranging the first anchoring section, the grouting stop ring and the threading, the prestressed anchor rod can be conveniently preloaded after installation, thereby increasing the friction between different rock layers, and clamping the surrounding rock within the anchoring range to form a beam or arch bearing structure, thereby improving the stability of the tunnel surrounding rock; the single prestressed anchor rod is reasonably distributed in the surrounding rock, and the compressed areas are superimposed and interact with each other, so that the surrounding rock within a certain range can be reinforced, and the deformation and development of the plastic zone can be effectively reduced; after grouting and secondary grouting, the prestressed anchor rod is more stable and the anchor survival rate is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present utility model, the preferred implementation scheme of the present utility model is described below in conjunction with specific embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent elements with the same or similar functions. However, it should be understood that the accompanying drawings are only used for illustrative purposes and cannot be understood as limitations on the present utility model. In order to better illustrate the present embodiment, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted, and the positional relationship described in the accompanying drawings is only used for illustrative purposes and cannot be understood as limitations on the present utility model.

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0021] The utility model provides a prestressed anchor structure for a high-ground stress soft rock large deformation tunnel, comprising a prestressed anchor 1, a grouting pipe 2 is fixed to one side of the prestressed anchor 1, a grouting pipe 3 is fixed to the other side of the prestressed anchor 1, the prestressed anchor 1 comprises a first anchoring section 11 and a second anchoring section 12, a grouting stop ring 4 is provided at the junction of the first anchoring section 11 and the second anchoring section 12, and a thread 5 is provided at the end of the second anchoring section 12 away from the grouting stop ring 4.

[0022] The length of the first anchoring section 11 is one sixth of the length of the prestressed anchor rod 1 .

[0023] In this embodiment, the length of the first anchoring section 11 is 1.5 m.

[0024] The grouting pipe 2 is fixedly connected to the second anchoring section 12 . An opening 21 is provided on one side of the grouting pipe 2 . The distance between the opening 21 and the grouting stop ring 4 is one fifteenth of the length of the second anchoring section 12 .

[0025] In this embodiment, the distance between the opening 21 and the grout-stopping ring 4 is 0.5 m, and the shortest distance between the opening 21 and the end of the grouting pipe 2 is 20 cm.

[0026] The length of the thread 5 is 10 cm.

[0027] The return slurry pipe 3 is fixed to one end of the second anchoring section 12, and the overlapping length of the return slurry pipe 3 and the second anchoring section 12 is 40 cm.

[0028] A plurality of fixed connectors 6 are provided outside the grouting pipe 2 and the return grouting pipe 3 , and the fixed connectors 6 fixedly connect the grouting pipe 2 , the return grouting pipe 3 and the prestressed anchor rod 1 .

[0029] The fixed connection member 6 is a tape used for binding.

[0030] The prestressed anchor rod 1 is a threaded steel bar with a length of 9 m and a diameter of 32 mm.

[0031] In this embodiment, the exposed length of the prestressed anchor rod 1 at the opening of the anchor hole does not exceed 10 cm.

[0032] The grouting pipe 2 and the return grouting pipe 3 are both PVC pipes with an inner diameter of 14 mm and an outer diameter of 16 mm.

[0033] The slurry-stopping ring 4 is a rubber ring or hemp silk.

[0034] In this embodiment, a steel pipe is sleeved on the outside of the prestressed anchor rod 1, and the grouting pipe 2 and the grouting pipe 3 are fixed on the outside of the steel pipe.

[0035] The utility model provides a construction method for a prestressed anchor rod structure of a high ground stress soft rock large deformation tunnel, comprising the following steps:

[0036] Step 1: Preparation: Ensure electricity supply at the construction site and make prestressed anchor rod 1;

[0037] Step 2: Positioning, drilling and hole cleaning: Positioning of prestressed anchor holes, mainly using anchor trolleys and three-arm hydraulic trolleys to drill holes, and high-pressure air to clean holes;

[0038] Step 3: Preparation for rod insertion: Cover the prestressed anchor rod 1 with a Φ50 steel pipe, expose the grouting pipe and the return grouting pipe along the outside of the Φ50 steel pipe, and tie them with adhesive tape;

[0039] Step 4: Arrange channel steel and anchor piers: Arrange [20a channel steel at the prestressed anchor hole, and arrange the anchor piers along the bottom of the channel steel. The anchor piers are cast with M30 cement mortar, and the thickness is generally 3~5cm, which can be adjusted according to the actual situation on site. The edge slope of the anchor pier is 1:1, the width of the upper end face is 20cm, and it is leveled to match the [20a channel steel;

[0040] Step 5, installing the anchor rod: install the prestressed anchor rod 1 manually by means of a crane, slowly insert the prestressed anchor rod 1 into the prestressed anchor rod hole, the exposed length of the hole opening shall not exceed 10 cm (i.e. the position of the thread 5 at the end of the prestressed anchor rod 1), and fix the anchor rod body in the center at the hole opening with a stone or wooden wedge;

[0041] Step 6: Grouting the first anchoring section once: The length of the grouting anchoring section is 1m. After the mortar is mixed in the grouting machine according to the designed mix ratio, it is directly injected into the prestressed anchor hole. The amount of slurry injected into a single hole is about 10-15L. The length is marked on the grouting pipe 2;

[0042] Step 7, tensioning and locking: After the prestressed anchor rod 1 is installed, tensioning and locking are carried out. The tensioning equipment uses AC60-300 and AC280-760 torque wrenches. Before the prestressed anchor rod 1 is tensioned, the torque wrench is calibrated. Before tensioning, the locking nut is put on the thread 5 of the exposed section of the anchor rod. Before the prestressed anchor rod 1 is formally tensioned, 20% of the design tensioning load is taken, and it is pre-tensioned 1 to 2 times to make its various parts in close contact. The order of tensioning force application values ​​is as follows: the first tensioning force is 25% of the design value, and the load is held for 5 minutes. Then the second tensioning is carried out, and the tensioning force is 50% of the design value. After holding the load for 5 minutes, the third tensioning is carried out, and the tensioning force is 75% of the design value. After holding the load for 5 minutes, the fourth tensioning is carried out, and the tensioning force is 100% of the design value. After the last tensioning force reaches the design value, the pressure is stabilized for 30 minutes to end the tensioning and lock. The elongation value of the anchor rod body should be measured for each tensioning, and the original record should be made. Within 48 hours after the prestressed anchor rod 1 is locked, if the prestress loss is found to be greater than 10% of the design value of the tension of the prestressed anchor rod 1, compensatory tensioning is carried out;

[0043] Step 8, secondary grouting: Use a grouting pump to pump cement mortar into the grouting pipe 2, and after the grouting pipe 3 is grouted, close the grouting pipe 3.

[0044] According to the description and drawings of the utility model, those skilled in the art can easily manufacture or use the high-stress soft rock large-deformation tunnel prestressed anchor rod structure of the utility model, and can produce the positive effects recorded in the utility model.

[0045] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present utility model and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two mechanisms, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to the specific circumstances.

[0046] In the description of the present invention, it should be understood that the terms "one end", "the other end", "outside", "inside", "horizontal", "end", "length", "outer end", "left", "right" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the mechanism or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. The terms "first" and "second" are also used only for the simplicity of description, and do not indicate or imply relative importance.

[0047] Furthermore, in practicing the claims of the present invention, those skilled in the art may understand and affect variations to the disclosed embodiments by studying the drawings, disclosure, and appended claims. In addition, in the claims and the specification, words such as "comprises", "comprising", etc. do not exclude other elements or steps, and non-plural nouns do not exclude their plural forms.

[0048] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the present invention are covered by the scope of the claims of the present invention and will not be listed one by one here.

Claims

1. A prestressed anchor structure for a high-in-situ stress soft rock large deformation tunnel, characterized in that: The invention comprises a prestressed anchor rod (1), a grouting pipe (2) being fixed on one side of the prestressed anchor rod (1), a return grouting pipe (3) being fixed on the other side of the prestressed anchor rod (1), the prestressed anchor rod (1) comprising a first anchoring section (11) and a second anchoring section (12), a grouting stop ring (4) being provided at the junction of the first anchoring section (11) and the second anchoring section (12), and a threading (5) being provided at one end of the second anchoring section (12) away from the grouting stop ring (4).

2. A high-stress soft rock large deformation tunnel prestressed anchor structure as claimed in claim 1, characterized in that: The length of the first anchoring section (11) is one sixth of the length of the prestressed anchor rod (1).

3. A high-stress soft rock large-deformation tunnel prestressed anchor structure as claimed in claim 1, characterized in that: The grouting pipe (2) is fixedly connected to the second anchoring section (12), and an opening (21) is provided on one side of the grouting pipe (2), and the distance between the opening (21) and the grouting stop ring (4) is one fifteenth of the length of the second anchoring section (12).

4. A high-stress soft rock large deformation tunnel prestressed anchor structure as claimed in claim 1, characterized in that: The length of the thread (5) is 10 cm.

5. The high-stress soft rock large deformation tunnel prestressed anchor structure according to claim 1, characterized in that: The return slurry pipe (3) is fixed to one end of the second anchoring section (12), and the overlapping length of the return slurry pipe (3) and the second anchoring section (12) is 40 cm.

6. A high-stress soft rock large deformation tunnel prestressed anchor structure as claimed in claim 1, characterized in that: A plurality of fixed connecting pieces (6) are provided outside the grouting pipe (2) and the return grouting pipe (3), and the fixed connecting pieces (6) fixedly connect the grouting pipe (2), the return grouting pipe (3) and the prestressed anchor rod (1).

7. A high-stress soft rock large deformation tunnel prestressed anchor structure as claimed in claim 6, characterized in that: The fixed connection piece (6) is an adhesive tape used for binding.

8. The high-stress soft rock large deformation tunnel prestressed anchor structure according to claim 1, characterized in that: The prestressed anchor rod (1) is a threaded steel bar with a length of 9 m and a diameter of 32 mm.

9. The high-in-situ stress soft rock large deformation tunnel prestressed anchor structure according to claim 1, characterized in that: The grouting pipe (2) and the grouting pipe (3) are both PVC pipes with an inner diameter of 14 mm and an outer diameter of 16 mm.

10. The high-in-situ stress soft rock large deformation tunnel prestressed anchor structure according to claim 1, characterized in that: The slurry-stopping ring (4) is a rubber ring or hemp thread.

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