Working method for achieving constant tension and large deformation of anchor rod

Abstract

The invention discloses a working method for realizing constant tension and large deformation of an anchor rod, which is characterized by comprising the following steps of: firstly, manufacturing a hydraulic tension device consisting of a cylinder body and a piston assembly; when the hydraulic anchor rod is used, the hydraulic anchor rod is arranged in a surrounding rock anchor hole stuffed with an anchoring agent, after the hydraulic anchor rod is solidified firmly, a lengthened liquid injection pipe is connected to a liquid injection opening of the one-way valve through a quick connector, liquid is injected into a sealing cavity through a liquid injection gun, the anchor rod is tensioned, and then the anchor rod is pulled out. The liquid pressure value is calculated according to the magnitude of the pre-tightening force applied to the surrounding rock, when the surrounding rock expands and deforms, part of the emulsion is released, the expansion energy in the surrounding rock is released, and the pre-tightening force is returned to the set pre-tightening force; when the surrounding rock expands and deforms again, the process is repeated, and the constant tension is always kept to adapt to continuous expansion deformation of the surrounding rock.

Description

Technical Field

[0001] The invention relates to mining, and in particular to a tunnel anchor support technology. Background Art

[0002] In mining, anchor support is currently the most common and effective support method for tunnel surrounding rock. According to the current geological conditions of deeper and deeper mines, when the rock mass has swelling characteristics such as water absorption and stress relief, the surrounding rock will produce swelling pressure. The expansion deformation of the surrounding rock places higher and higher requirements on anchor support. In order to purposefully control the deformation of the surrounding rock and make the anchor play a role within the effective tensile strength, according to the pressure-yielding principle of controlling the deformation of the surrounding rock, most of them use constant resistance large deformation anchors for support. The structure of the existing constant resistance large deformation anchor is friction type, which consists of a constant resistance device, a rod body, a tray and a nut. Among them, the constant resistance device includes a constant resistance casing and a constant resistance body (i.e., large and small casings), the constant resistance device is connected to the tail of the rod body, the tray and the nut are successively installed at the tail of the constant resistance device, and the pre-tightening force is applied by tightening the nut. The design principle of the existing constant resistance large deformation rod is: when the surrounding rock deformation energy is small and the axial force applied to the rod is less than the designed constant tension of the constant resistance large deformation rod, the constant resistance device does not move at all due to static friction, and relies on the elastic deformation of the rod material to resist the deformation and damage of the rock mass. (2) When the axial force applied to the rod is greater than or equal to the designed constant tension of the constant resistance large deformation rod, the constant resistance body in the constant resistance device slides along the inner wall of the casing, and the constant resistance characteristics are maintained by dynamic and static friction, and the deformation and extension of the constant resistance device are relied on to resist the deformation and damage of the rock mass.

[0003] Since this type of constant resistance large deformation anchor rod relies on the resistance of the constant resistance body to work, it is called a constant resistance large deformation anchor rod. The size of its dynamic friction and static friction is controlled by the expansion of the inner cylindrical surface of the casing. Due to the manufacturing process and the material itself, the dynamic friction 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 due to friction during the deformation process; 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 is not scientific enough. Therefore, a more scientific method is needed to solve the problem of large deformation of the rod body under constant force.

[0004] The term “large deformation” mentioned above refers to the general deformation of the surrounding rock, and is not a specific deformation value. Summary of the invention

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

[0006] A working method for realizing large deformation of anchor rod under constant tension, 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 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 the anchor rod body; the cylinder and the piston assembly form a closed chamber; a one-way valve injection port and a relief valve communicating with the closed chamber are provided on the end face of the piston; 80-90% of the volume of emulsion is injected into the closed chamber, and 10-20% of the space is reserved for the fourth step of injection to apply preload; 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 with 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] Step 4: Sleeve the anchor pad 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, make the flange 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 pipe:

[0011] The fifth step, after solidification, connect the extended injection pipe to the injection port of the one-way valve with a quick connector, connect the injection gun to the extended injection pipe, start the injection pump, inject high-pressure liquid into the sealing cavity, tension the anchor rod, tension to the P0 value, and stop 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 sealing cavity, and the P0 value is displayed instantly 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 reached, the cylinder will open and release some emulsion. As the amount of liquid in the cylinder decreases, the piston rod will extend to release the expansion energy in the surrounding rock and return to the set preload. When the surrounding rock expands and deforms again, the above process is repeated to maintain constant tension to adapt to the continued expansion and deformation of the surrounding rock.

[0013] In the above scheme, in order to reuse the hydraulic tensioner, the piston rod and the anchor rod body are connected by a threaded connection sleeve.

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

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

[0016] The working principle is: the working of the anchor body in the surrounding rock is divided into three stages.

[0017] The first stage is the elastic deformation stage of the rod body; when the stress generated by the tunnel surrounding rock changes, it will expand and deform. When the deformation force does not reach the pressure P controlled by the overflow valve M When the load is increased, this deformation is compensated by the elastic deformation of the rod and the tray.

[0018] The second stage is the extension stage of rod deformation. As the stress of the tunnel surrounding rock changes, the axial force N applied to the rod gradually increases, and the emulsion pressure P in the device also gradually increases. When P>=P M When the overflow valve opens, part of the emulsion overflows, the cylinder pressure decreases, and the piston rod produces a displacement L. When the surrounding rock pressure P<P M When the overflow valve is closed, the piston rod stops moving. During the movement, the tension value of the anchor rod body decreases with the increase of 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 is repeatedly pressed, the above process is repeated, and finally the purpose of constant tension and large deformation is achieved.

[0020] When the working surface application is completed, the hydraulic tensioner can be removed from the threaded connection sleeve using tools and reused after repair.

[0021] The positive effects of this application are: 1. The tension is achieved by using a hydraulic cylinder, and the pressure gauge directly displays accurate tension data. 2. When the surrounding rock of the tunnel is deformed, the overflow valve automatically adjusts the cylinder pressure, and the anchor body can be extended multiple times under constant tension as the surrounding rock deforms to adapt to the prominent characteristics of large deformation of the surrounding rock. 3. The piston rod of the hydraulic tensioner and the anchor body are designed as a movable connection structure, so that the hydraulic tensioner can be recycled and reused, greatly reducing the project cost.

[0022] This application, if the anchor rod body is replaced with an anchor cable, becomes a working method for realizing the large deformation of the anchor rod constant tension. At this time, a section of threaded rod will be welded on the connecting head of the anchor cable to facilitate the threaded connection of the connecting sleeve and the hydraulic tensioner. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the hydraulic anchor rod according to the embodiment of the present application. Figure 2 is an operational state diagram of an embodiment, Figure 3 It is a working state diagram of the embodiment.

[0024] Legend: 1. Anchor rod body, 2. Threaded connecting 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. Filling gun, 13. Anchoring agent, 14. Surrounding rock, 15. Anchor plate, 16. Sealing cover. 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 deformation of the surrounding rock, and the open end of the cylinder body 4 is provided with a flange 8 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 the anchor rod body 1; the cylinder body 4 and the piston assembly form a closed cavity; 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 cavity. A one-way valve injection port 7 and a relief valve 9 communicating with the closed cavity are provided on the end face of the piston 4; 80-90% of the volume of emulsion is injected into the closed cavity, and 10-20% of the space is reserved for the fourth step of injection to apply preload; the emulsion 5 can be injected through the one-way valve injection port 7; the relief valve 9 is 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, forming a stepped drilling.

[0030] The fourth step is to install the hydraulic anchor rod, such as Figure 2 As shown, first, insert the anchor pad 15 onto the hydraulic anchor rod to the flange 8, insert the anchor 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 anchor 13, and make the flange 8 close to the borehole mouth, waiting for the anchor 13 to solidify.

[0031] During the curing process, prepare the injection pump, injection gun and extended injection tube.

[0032] Step 5: After solidification, Figure 2 As shown, an extended injection tube 10 is connected to the injection port 7 of the one-way valve through a quick connector 11, the extended injection tube 10 is connected to the injection gun 12, the inlet of the injection gun 12 is connected to the injection pump, and the injection gun 12 must be connected to a pressure gauge to display the injection pressure in real time.

[0033] Start the injection pump, inject high-pressure liquid into the sealed cavity, and tension the anchor rod to the P0 value. The P0 value is the liquid pressure value calculated according to the size of the preload force applied to the surrounding rock 14. P0 = N0 / A, N0 is the preload force, A is the effective pressure area of ​​the piston 6a, and the P0 value is displayed instantly by the pressure gauge. After tensioning is completed, unscrew the quick connector 11, remove the injection gun 12 and the injection extension tube 10, and the installation is completed. Figure 2 shown.

[0034] In order to prevent debris from entering the cylinder body from the open end during anchoring, a sealing cover 16 is provided at the open end of the cylinder body, and the cylinder body opening is covered with the sealing cover during operation.

[0035] Step 6: Figure 2 As shown, when the surrounding rock 14 expands and deforms, the hydraulic tensioner generates a tension that reaches the set working pressure P of the relief valve 9. M When the pressure is released, the cylinder automatically opens to release part of the emulsion 5. When the pressure is released, the amount of liquid in the cylinder decreases, and the piston 6a moves inward, that is, the piston rod 6 extends and lengthens. Figure 3 As shown, the expansion energy in the surrounding rock 14 is released and returns to the set preload; when the surrounding rock 14 expands and deforms again, the above process is repeated, and the constant tension is always maintained to adapt to the continued expansion and deformation of the surrounding rock.

[0036] When the working face coal mining is completed and the tunnel is abandoned, the hydraulic tensioner is rotated by special tools and removed from the threaded connection sleeve 2, and can be reused after repair.

Claims

1. A working method for achieving constant tension and large deformation of anchor rods is as follows: The first step is to make a hydraulic tensioner. The hydraulic tensioner consists of a cylinder and a piston assembly. The diameter of the cylinder is suitable for the diameter of the surrounding rock anchor hole, and a flange is provided at the open end of the cylinder. The piston assembly is a connected piston and piston rod, and the piston rod extends from the bottom of the cylinder. The cylinder and the piston assembly form a closed cavity. The piston end surface is provided with a one-way valve injection port and a relief valve connected to the closed cavity. 80-90% of the volume of emulsion is injected into the closed cavity. The relief valve is adjusted in advance to a working pressure P M , P M The value is the maximum pressure that controls the expansion of the surrounding rock; 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: The third step is to install the hydraulic anchor rod. First, insert the anchor pad onto the hydraulic anchor rod to the flange, insert the anchoring agent into the bottom of the pre-drilled surrounding rock anchor hole, push the hydraulic anchor rod into the surrounding rock anchor hole and extend it into the anchoring agent, make the flange close to the drill hole, and wait for the anchoring agent to solidify. During the solidification process, prepare the injection pump and injection gun: The fourth step is to start the injection pump after solidification, and use the injection gun to inject high-pressure liquid into the sealed cavity through the injection port of the one-way valve to tension the anchor rod. When tension reaches the P0 value, 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; Step 5: 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 reached, part of the emulsion is automatically discharged. As the amount of liquid in the cylinder decreases, the piston rod extends and releases the expansion energy of 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.

2. The method for realizing large deformation of anchor rod under constant tension as claimed in 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 working method for realizing constant tension and large deformation of anchor rods as claimed in claim 1, characterized in that: A sealing cover is arranged on the opening of the cylinder body.

4. The method for realizing large deformation of anchor rod under constant tension as claimed in claim 1, characterized in that: The rod body and the hydraulic tensioner are connected together through a threaded connection sleeve.

5. The working method for realizing large deformation of anchor rod under constant tension as claimed in claim 1, characterized in that: In the third step, when the diameter of the hydraulic tensioner is larger than the borehole diameter, the hole mouth section of the surrounding rock anchor hole is firstly expanded, the expanded hole diameter is larger than the cylinder diameter, and the expanded hole depth is greater than or equal to the cylinder length.

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