A working method for realizing constant tension of anchor rod with large deformation

Abstract

The application discloses a working method for realizing constant tension of anchor rod with large deformation, which is characterized in that a hydraulic tensioner is first made, and the hydraulic tensioner is composed of a cylinder body and a piston assembly; a piston rod of the hydraulic tensioner is connected with an anchor rod body to form a hydraulic anchor rod; in use, the hydraulic anchor rod is put into a surrounding rock anchor hole filled with anchoring agent, and after being solidified and fixed, a lengthened liquid injection pipe is connected to a one-way valve liquid injection opening through a quick connector, a liquid injection gun is used to inject liquid into a sealed cavity, the anchor rod is tensioned, and the tensioning is stopped when the liquid pressure value calculated according to the pre-tightening force applied to the surrounding rock is reached; when the surrounding rock expands and deforms, the automatic opening of the liquid injection opening releases part of the emulsion, the expansion energy in the surrounding rock is released, and the pre-tightening force is returned to the set value; when the surrounding rock expands and deforms again, the above process is repeated, and the constant tension is maintained to adapt to the continuous expansion and deformation of the surrounding rock.

Description

TECHNICAL FIELD

[0001] The present application relates to mine exploitation, in particular to roadway bolting technology. BACKGROUND

[0002] In mine exploitation, bolting is the most common and effective support method for roadway surrounding rock. According to the current geological conditions of increasingly deep mines, when the rock mass has swelling characteristics such as water absorption and stress relief, the surrounding rock generates swelling pressure. The swelling deformation of the surrounding rock puts higher and higher requirements on bolting. In order to purposefully control the deformation of the surrounding rock and make the anchor rod work within the effective tensile strength, according to the pressure relief principle of controlling the deformation of the surrounding rock, constant resistance large deformation anchors are mostly used for support. The structure of the existing constant resistance large deformation anchor is friction type, which is composed of a constant resistance device, a rod body, a tray and a nut. The constant resistance device includes a constant resistance sleeve and a constant resistance body (i.e. large and small sleeves), and is connected to the tail of the rod body. The tray and the nut are installed in the tail of the constant resistance device in sequence, and the pre-tightening force is applied by tightening the nut. The design principle of the existing constant resistance large deformation rod body is: when the deformation of the surrounding rock is small, the axial force applied to the rod body is less than the design constant tension of the constant resistance large deformation rod body, the constant resistance device relies on static friction to not move at all, and relies on the elastic deformation of the rod body material to resist the deformation and damage of the rock mass. (2) When the axial force applied to the rod body is greater than or equal to the design constant tension of the constant resistance large deformation rod body, the constant resistance body in the constant resistance device slips along the inner wall of the sleeve, relies on the dynamic and static friction to maintain the constant resistance characteristic, and relies on the deformation extension of the constant resistance device to resist the deformation and damage of the rock mass.

[0003] Since this constant resistance large deformation anchor relies on the resistance of the constant resistance body to work, it is called a constant resistance large deformation anchor, and the size of the dynamic and static friction is controlled by the expansion of the inner cylindrical surface of the sleeve. Due to the manufacturing process and the material itself, the dynamic and static friction values of each rod cannot be consistent, so the so-called "constant resistance" is not constant and uncertain, and it is easy to fail in friction during deformation. At the same time, the pre-tensioning force is applied by tightening the nut, and the size of the tightening force depends on personal experience and control, which lacks scientificity. Therefore, a more scientific method is needed to solve the problem of large deformation of the rod body under constant force.

[0004] The "large deformation" term above is relative to the general deformation of the surrounding rock, and is not a specific deformation value. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, a working method for realizing constant tension large deformation of an anchor rod is invented to solve the problem of large deformation of the anchor rod under constant force.

[0006] A working method for realizing constant tension large deformation of an anchor rod, characterized in that,

[0007] The first step is to make a hydraulic tensioner, which consists of a cylinder and a piston assembly. The length of the cylinder is greater than the expansion and deformation of the surrounding rock, and the open end of the cylinder is provided with a flange larger than the diameter of the anchor hole. The piston assembly is a connected piston and piston rod, and the piston rod extends from the bottom of the cylinder to connect to the anchor rod body. The cylinder and the piston assembly form a closed chamber. The piston end face is provided with a one-way valve injection port and a relief valve communicating with the closed chamber. The closed chamber is filled with 80-90% of the emulsion capacity, leaving 10-20% of space for the preload force applied by the fourth step of injection. The working pressure P of the relief valve is adjusted in advance. M , P M The value is the maximum pressure that controls the expansion of the surrounding rock;

[0008] The second step is to connect the piston rod of the hydraulic tensioner to the existing anchor rod body to form a hydraulic anchor rod for standby use;

[0009] The third step is to drill anchor holes in the surrounding rock according to the design, and then expand the hole section of the surrounding rock. The expansion diameter matches the cylinder diameter, and the expansion depth is greater than or equal to the cylinder length.

[0010] The fourth step is to insert the anchor plate onto the hydraulic anchor rod to the flange, insert the anchoring agent into the bottom of the surrounding rock anchor hole, push the hydraulic anchor rod into the surrounding rock anchor hole and extend it into the anchoring agent, so that the flange is close to the anchor hole mouth, and wait for the anchoring agent to solidify; during the solidification process, prepare the injection pump, injection gun and extended injection tube:

[0011] The fifth step is to connect the extended injection pipe to the injection port of the one-way valve with a quick connector after solidification, connect the injection gun to the extended injection pipe, start the injection pump, inject high-pressure liquid into the sealed cavity, tension the anchor rod, tension it to the P0 value, and stop the injection; the P0 value is the liquid pressure value calculated according to the size of the preload force applied to the surrounding rock, P0 = N0 / A, N0 is the preload force, A is the effective area of ​​the piston in the sealed cavity, and the P0 value is displayed immediately by the pressure gauge of the injection gun; after tensioning, unscrew the quick connector and the injection gun, and the installation is complete.

[0012] Step 6: When the surrounding rock expands and deforms, the hydraulic tensioner generates tension, and the tension reaches the set relief valve working pressure P M When the preload is set, the valve automatically opens to release part of the emulsion. As the amount of liquid in the cylinder decreases, the piston rod extends and releases the expansion energy in the surrounding rock, returning to the set preload. When the surrounding rock expands and deforms again, the above process is repeated, and constant tension is always maintained to adapt to the continued expansion and deformation of the surrounding rock.

[0013] In the above solution, in order to make the hydraulic tensioner reusable, the piston rod and the anchor rod body are connected by a threaded coupling sleeve.

[0014] In order to prevent the cylinder from entering sundries from the open end during anchoring, a sealing cover is arranged at the open end of the cylinder, and the sealing cover is used to cover the open end of the cylinder after tensioning is completed.

[0015] In order to further understand the advantages of the anchor rod, the working principle is further described.

[0016] The working principle is that the anchor rod body works in three stages in the surrounding rock.

[0017] The first stage is the elastic deformation stage of the rod body; the stress generated by the surrounding rock of the roadway changes and then expands and deforms. When the deformation force does not reach the pressure P controlled by the overflow valve, M the deformation amount is compensated by the elastic deformation of the rod body and the tray.

[0018] The second stage is the deformation and extension stage of the rod body; with the change of the stress of the surrounding rock of the roadway, the axial force N applied to the rod body gradually increases, and the emulsion pressure P in the device also gradually increases. When P >= P M , the overflow valve opens to overflow part of the emulsion, the cylinder pressure decreases, and the piston rod generates a displacement L. When the surrounding rock pressure P < P M , the overflow valve is closed, and the piston rod stops moving. In the moving process, the tension value of the anchor rod body decreases with the increase of the displacement, the stress of the surrounding rock is released, the deformation of the rock mass is resisted, and a new stable state of the rock mass is formed.

[0019] The third stage is the repeated adjustment and stabilization stage; when the surrounding rock repeatedly comes under pressure, the above process is repeated, and the purpose of constant tension and large deformation is finally achieved.

[0020] After the working face is applied, the hydraulic tensioner can be removed from the threaded coupling sleeve using a tool, and after trimming, it can be reused.

[0021] The positive effects of the present application are: 1. The hydraulic oil cylinder is used to realize tensioning, and the accurate tension data is directly displayed by the pressure gauge. 2. When the surrounding rock of the roadway deforms, the oil cylinder pressure is automatically adjusted by the overflow valve, and the anchor rod body can be extended multiple times under constant tension to adapt to the prominent feature of large deformation of the surrounding rock. 3. The piston rod of the hydraulic tensioner and the anchor rod body are designed as a movable coupling structure, which can recycle the hydraulic tensioner, greatly reducing the engineering cost.

[0022] The present application is changed into an anchor cable, which becomes a working method for realizing constant tension and large deformation of the anchor rod. At this time, a threaded rod is welded on the connector of the anchor cable to facilitate the threaded connection of the coupling sleeve and the hydraulic tensioner. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The structural principle diagram of the hydraulic anchor rod of the embodiment of the present application, Figure 2 the operation state diagram of the embodiment.Figure 3 FIG. 2 is a working state diagram of an embodiment.

[0024] Legend: 1. Anchor rod body, 2. Threaded coupling sleeve, 3. Sealing ring, 4. Cylinder body, 5. Emulsion, 6. Piston rod, 6a. Piston, 7. One-way valve filling port, 8. Flange, 9. Overflow valve, 10. Extended filling pipe, 11. Quick connector, 12. Injection gun, 13. Anchoring agent, 14. Surrounding rock, 15. Anchor plate, 16. Sealing cap. DETAILED DESCRIPTION

[0025] The embodiments are further described with reference to the accompanying drawings.

[0026] A working method for achieving constant tension and large deformation of anchor rods is as follows:

[0027] The first step is to make a hydraulic tensioner. Figure 1 As shown, the hydraulic tensioner consists of a cylinder body 4 and a piston assembly; the length of the cylinder body 4 is greater than the expansion and deformation of the surrounding rock, and the open end of the cylinder body 4 is provided with a flange 8 that is larger than the diameter of the anchor hole; the piston assembly is a connected piston 6a and piston rod 6, and the piston rod 6 extends from the bottom of the cylinder body 4 to connect to the anchor rod body 1; the interior of the cylinder body 4 and the piston assembly form a closed chamber; in order to achieve sealing, a sealing ring (unnumbered) is provided between the piston 6a and the cylinder body 4, and a sealing ring 3 is provided between the piston rod 6 and the bottom of the cylinder body 4, so that the rod body cavity forms a tightly sealed chamber. A one-way valve injection port 7 and a relief valve 9 are provided on the end face of the piston 4, which are connected to the closed chamber; 80-90% of the capacity of the emulsion is injected into the closed chamber, and 10-20% of the space is reserved for the fourth step of injection to apply preload force; the emulsion 5 can be injected through the one-way valve injection port 7; the relief valve 9 can be adjusted in advance to the working pressure P M , P M The value is the maximum pressure that controls the expansion of the surrounding rock.

[0028] The second step is to connect the piston rod 6 of the hydraulic tensioner with the existing anchor rod body 1 to form a hydraulic anchor rod. Figure 1 As shown, the piston rod extends from the bottom of the cylinder body and is movably connected to the rod body through a threaded connecting sleeve 2 for standby use.

[0029] The third step is to drill anchor holes on the surrounding rock 14 according to the design, and then expand the surrounding rock hole section. The expansion diameter matches the outer diameter of the cylinder body 4, and the expansion depth is greater than or equal to the length of the cylinder body 4 to form a stepped drilling.

[0030] The fourth step is to install the hydraulic anchor rod, such as Figure 2 As shown, first insert the anchor plate 15 onto the hydraulic anchor rod to the flange 8, insert the anchoring agent 13 into the bottom of the borehole in the surrounding rock 14, install the hydraulic anchor rod into the anchor hole in the surrounding rock and penetrate into the anchoring agent 13, and make the flange 8 close to the borehole mouth, waiting for the anchoring agent 13 to solidify.

[0031] During the curing process, the liquid injection pump, the liquid injection gun and the extended liquid injection pipe are prepared.

[0032] In the fifth step, after the solidification is firm, the extended liquid injection pipe 10 is connected to the one-way valve liquid injection port 7 through the quick connector 11, the extended liquid injection pipe 10 is connected to the liquid injection gun 12, the inlet of the liquid injection gun 12 is connected to the liquid injection pump, and the liquid injection gun 12 must be connected to the pressure gauge to display the injection pressure in real time. Figure 2

[0033] The liquid injection pump is started to inject high-pressure liquid into the sealed cavity to tension the anchor rod. The tensioning is performed to the P0 value, which is the liquid pressure value calculated according to the pre-tightening force applied to the surrounding rock 14. The P0 value is calculated as P0=N0 / A, where N0 is the pre-tensioning force and A is the effective pressure receiving area of the piston 6a. The P0 value is displayed in real time by the pressure gauge. After the tensioning is completed, the quick connector 11 is unscrewed, and the liquid injection gun 12 and the liquid injection extended pipe 10 are removed. The installation is completed as shown in FIG. 6. Figure 2

[0034] In order to prevent foreign matter from entering the cylinder from the open end during anchoring, a sealing cover 16 is arranged at the open end of the cylinder, and the sealing cover is used to cover the open end of the cylinder during work.

[0035] In the sixth step, when the surrounding rock 14 expands and deforms, the hydraulic tensioner generates tension. When the tension reaches the working pressure P of the overflow valve 9, the overflow valve 9 is automatically opened to release part of the emulsion 5, and the liquid volume in the cylinder is reduced. The piston 6a moves inward, i.e., the piston rod 6 is extended, as shown in FIG. 7, so that the expansion energy in the surrounding rock 14 is released, and the surrounding rock 14 returns to the set pre-tightening force. When the surrounding rock 14 expands and deforms again, the above process is repeated to maintain a constant tension to adapt to the continuous expansion and deformation of the surrounding rock. Figure 2 M When the working face is completed and the roadway is abandoned, the hydraulic tensioner is rotated by using a special tool to dismount the hydraulic tensioner from the threaded coupling sleeve 2. After the repair, the hydraulic tensioner can be reused. Figure 3

[0036] When the working face is completed and the roadway is abandoned, the hydraulic tensioner is rotated by using a special tool to dismount the hydraulic tensioner from the threaded coupling sleeve 2. After the repair, the hydraulic tensioner can be reused.​​​​

Claims

1. A working method for realizing constant tension of anchor rod with large deformation, comprising the following steps: First, make hydraulic tensioner; hydraulic tensioner is composed of cylinder and piston assembly; The diameter of the cylinder is suitable for the diameter of the surrounding rock anchor hole, and the open end of the cylinder is provided with a flange; The piston assembly is a connected piston and piston rod, and the piston rod extends from the bottom of the cylinder; The inside of the cylinder and the piston assembly form a closed cavity; The piston end face is provided with a one-way valve liquid injection port and an overflow valve communicating with the closed cavity; 80-90% of the capacity of the closed cavity is filled with emulsion; The working pressure P M of the overflow valve is adjusted beforehand, and the P M value is the maximum pressure for controlling the expansion of the surrounding rock; In the second step, the piston rod of the hydraulic tensioner is connected with the existing anchor rod body through a threaded connecting sleeve to form a hydraulic anchor rod, which is ready for use; In the third step, an anchor hole is drilled in the surrounding rock, and the hole is reamed at the hole mouth section, the reaming diameter is matched with the outer diameter of the cylinder body, and the reaming depth is greater than or equal to the length of the cylinder body; the hydraulic anchor rod is installed: first, the anchor pad is sleeved on the hydraulic anchor rod to the flange, the anchor agent is inserted into the bottom of the drilled anchor hole in the surrounding rock, the hydraulic anchor rod is pushed into the anchor hole in the surrounding rock and extends into the anchor agent, the flange is tightly attached to the hole mouth, and the anchor agent is solidified; during the solidification process, the liquid injection pump and the liquid injection gun are prepared; In the fourth step, after the solidification is firm, the liquid injection pump is started, the liquid injection gun is used to inject high-pressure liquid into the sealed cavity through the one-way valve injection port, the anchor rod is tensioned, and the tensioning is stopped when the P0 value is reached; the P0 value is the liquid pressure value calculated according to the pre-tightening force applied to the surrounding rock; The fifth step, when the surrounding rock expands and deforms, the hydraulic tensioner generates tension, and the tension reaches the set relief valve working pressure P M When the surrounding rock expands and deforms, the hydraulic tensioner generates tension, and the tension reaches the set relief valve working pressure P When the surrounding rock expands and deforms again, the above process is repeated, and the constant tension is always maintained to adapt to the continuous expansion and deformation of the surrounding rock.

2. The method for achieving large deformation of anchor rods under constant tension according to claim 1, characterized in that: Sealing rings are arranged between the piston and the cylinder body and between the piston rod and the bottom of the cylinder body.

3. The method of claim 1, wherein the method comprises: A sealing cover is arranged on the open end of the cylinder body.

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