Impact-resistant multi-stage coordinated pressure-yielding anchor rod and implementation method thereof

Abstract

The present invention discloses an impact-resistant multi-stage coordinated pressure-yielding anchor rod and a method for realizing the same, which comprises a first pressure-yielding device arranged at a locking section of an anchor rod body, a second pressure-yielding device arranged at an anchoring section of the anchor rod body and a radial support device arranged at a free section of the anchor rod body, wherein the first pressure-yielding device is arranged between a tray and a nut to apply a greater preload force to the surrounding rock; the second pressure-yielding device provides a buffer time for hydraulic startup in the first pressure-yielding device, and prevents the anchor rod from being broken when delamination occurs in the surrounding rock; the radial support device provides an initial radial support force, and when the impact dynamic load is small, the pressure-yielding device is avoided from being repeatedly started, thereby increasing the service life of the entire system; the three support devices achieve coordinated pressure-yielding according to changes in the impact load of the surrounding rock, and provide a method for supporting soft rocks with both excellent preload force and pressure-yielding effects.

Description

Technical Field

[0001] The invention relates to the technical field of mine pressure and tunnel support, and in particular to an impact-resistant multi-stage coordinated pressure-yielding anchor rod and a use method thereof. Background Art

[0002] With the large-scale exploitation of coal resources in my country, the coal resources in open-pit coal mines and shallow strata are becoming less and less, and coal mining continues to develop in depth. At the same time, the geological conditions of the tunnels are becoming more and more complex, the deformation of the tunnel surrounding rock is becoming more and more serious, the stress concentration of the tunnel surrounding rock is serious, and the frequency of rock burst is increasing. When the traditional support of deep mines is subjected to impact dynamic loads, it cannot effectively consume the strain energy suddenly generated inside the surrounding rock by giving way to pressure, resulting in anchor fracture, surrounding rock deviation, roof collapse and other accidents. The support and reinforced mining anchors of the traditional prestressed system are mostly non-extensible anchors. The support position state cannot change accordingly with the deformation of the tunnel, and cannot effectively solve the impact of the dynamic load. The anchors are broken because they cannot withstand the instantaneous impact. Most of the existing anchors are widely round steel bonded. This type of anchor has a certain ductility and performs well in static support. However, in tunnels with frequent impact dynamic loads, the tunnels will deform in a short period of time due to the influence of dynamic loads, forming loose areas and deformation areas. The traditional anchor support system cannot meet the support needs. The few yielding anchors have the disadvantages of insufficient yielding capacity and repeated operation of the yielding device.

[0003] Chinese patent application publication number CN 110778347 A discloses a yield anchor with adjustable yield parameters. The device can adjust the yield amount and yield position at will, but the hydraulic transmission part is installed inside the rock. When the hydraulic cavity is subjected to impact dynamic load, the wall of the hydraulic cavity is easily squeezed and broken, causing the hydraulic oil to flow out and the system to fail. Chinese application publication number CN113217062 A discloses a prestressed anchor with a telescopic arm and a method of use. The device has the function of enhancing prestress and preventing the anchor from falling off. However, when impact dynamic load occurs, the rock layer moves violently, the surrounding rock sinks, and the rigid anchor has poor ductility and is easy to break, causing the support system to fail.

[0004] In order to improve the pressure-releasing capacity, the applicant has applied for an invention patent for a recyclable impact-resistant multi-stage pressure-releasing device and method (see Chinese patent application publication number CN 114320406 A). The device can play a multi-stage pressure-releasing function and can withstand reciprocating loads and impact loads. In actual applications, the applicant found that: first, the multi-stage pressure-releasing function of the multi-stage pressure-releasing device is entirely realized by the hydraulic pressure-releasing component outside the hole. When the spring is compressed to the limit, once the impact dynamic load appears, the hydraulic pressure-releasing component will immediately start regardless of the impact force. The component is easy to be damaged, affecting the progress of the project; second, for weak rocks, the mechanical strength of shallow rocks is low, and they are easily softened when exposed to water. They are easy to produce compression deformation under the action of external loads. At the same time, the instantaneous stress of the deep surrounding rock is large, and the anchor rod needs to be able to withstand the instantaneous impact force without being broken. Therefore, in order to prevent the compression deformation of the shallow surrounding rock and ensure the depth In order to obtain continuous support for the surrounding rock, we hope that the anchor rod has multiple pressure-releasing functions and that the preload force loaded on the soft rock wall is large so that the compressive stress it bears is smaller. However, the contact area between the hydraulic chamber of this technology and the rock wall is small, which makes the preload force of the hydraulic pressure-releasing component on the surrounding rock small and cannot be applied to soft rock support. Third, the spring is a hollow cylindrical structure with a small principal moment of inertia of its cross section and a small critical load for compression instability. Even if the spring is limited by the anchor rod body, it is still very easy to become unstable when it is suddenly compressed under strong impact dynamic load, thus causing a safety accident.

[0005] In order to adapt to soft rock support, most of them currently use grouting anchor rods. Some also change the nut structure to prevent thread slippage or use threaded anchor rods to increase preload. However, preload and pressure relief are difficult to be compatible, because the purpose of preload is to make the overall structure more tight and not easy to relax and deform under external forces, while pressure relief makes the structure have more freedom, so that the internal structure can better produce strain relaxation under the action of external forces, thereby reducing the internal stress concentration. Based on the above reasons, in order to adapt to soft rock support, it is urgent to develop an anchor rod with both excellent preload and pressure relief effects. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides an impact-resistant multi-stage coordinated pressure-yielding anchor rod and a method of use, which can effectively improve the support conditions of tunnel surrounding rock, extend the service life of the anchor rod, and ensure the life safety of underground personnel.

[0007] Note: The front end and rear end of the anchor rod in the present invention are defined by the state of the anchor rod when in use, wherein the front end refers to the anchoring end of the anchor rod (i.e. the bottom end of the hole), the rear end refers to the locking end of the anchor rod (i.e. the end outside the hole), and the free section of the anchor rod refers to the section between the anchoring end and the locking end of the anchor rod, wherein "end" represents a certain part, and the area where a certain end is located is called a "segment".

[0008] In order to solve the above problems, the technical solution adopted by the present invention is: an impact-resistant multi-stage coordinated pressure-yielding anchor rod, which includes an anchor rod body, a tray and a nut, and is characterized in that it includes a first pressure-yielding device arranged at the rear section of the anchor rod body, a second pressure-yielding device arranged at the front section of the anchor rod body and a radial support device arranged at the free section of the anchor rod body, wherein:

[0009] The front section and the free section of the anchor rod body are both provided with stoppers, which are respectively called spring stoppers and sleeve stoppers. The stoppers and the anchor rod body are an integrated structure. The anchor rod body behind the sleeve stopper and the part of the anchor rod body where the locking nut is installed are both provided with threads.

[0010] The first pressure-releasing device is arranged between the tray and the nut, and includes a trumpet-shaped shell, a piston sleeved on the anchor rod body, and a first spring. The closed end of the trumpet-shaped shell is the piston, and the open end is the tray. The piston, the tray, and the trumpet-shaped shell form a closed cavity as a hydraulic cavity, and a limiter is provided at the variable diameter portion in the closed cavity; the first spring is sleeved on the anchor rod, one end of the first spring presses on the locking nut, and the other end presses on the piston, and a one-way reflux valve and a filling valve are provided on the hydraulic cavity;

[0011] The second pressure-releasing device includes a spring sleeve and a second spring. The spring sleeve is sleeved on the front section of the anchor rod body and wraps the spring limiter inside. The front section of the spring sleeve is a solid structure wrapped around the circumference of the anchor rod body, and the rear end is a hollow cavity structure. The dividing point between the two is the spring limiter. The second spring is sleeved in the hollow structure and sleeved on the anchor rod body; that is, the left and right ends of the second spring are respectively pressed against the spring limiter and the spring sleeve, and the second spring is arranged in the hollow cavity of the spring sleeve. When the spring sleeve is compressed, it is not affected by the inner wall of the spring sleeve;

[0012] The radial support device comprises a steel radial expansion sleeve and a nut which can undergo plastic deformation. The nut is sleeved on the anchor rod body, the radial expansion sleeve is arranged around the anchor rod body, one end of the radial expansion sleeve is pressed against the sleeve limiter, and the other end is pressed against the nut.

[0013] Further: In order to prevent the first spring from losing stability during compression, a spring pressure-releasing restraint is provided on the periphery of the first spring, which not only limits the vertical displacement of the spring but also contracts as the spring is compressed. Preferably, the spring pressure-releasing restraint is a two-stage telescopic sleeve, which is formed by sleeves of inner and outer sleeves, the contact surfaces of the inner and outer sleeves are rough surfaces, and the inner diameter of the inner sleeve is required to be adapted to the outer diameter of the spring, and the outer diameter of the nut is larger than the outer diameter of the outer sleeve.

[0014] Further: In order to facilitate installation, the spring sleeve is formed by buckling together two parts, the upper and the lower parts.

[0015] Further: the anchor rod body and the stopper are cast into one piece by steel, and then threads are processed on the anchor rod body behind the sleeve stopper and on which the locking nut is installed.

[0016] Furthermore, rubber sealing rings are provided at the central mounting holes on the tray and the piston to prevent leakage of hydraulic oil.

[0017] Further: in order to reduce the compression force, the steel radial expansion sleeve is prefabricated with axial defects. Further, the structure with axial prefabricated defects is that axial blind holes or openings are symmetrically arranged around the middle of the plastic sleeve.

[0018] An impact-resistant multi-stage coordinated pressure-yielding anchor rod and a method of using the same, characterized in that the method comprises the following steps:

[0019] Step 1: Drill a hole on the rock to be supported as required, assemble the second pressure-releasing device and the anchor rod body outside the hole, then push the anchor rod to the bottom of the hole by starting the anchor rod mixer, and use the anchor rod agent to anchor the entire spring sleeve and the front end of the anchor rod to the surrounding rock;

[0020] Step 2: Install the radial expansion sleeve and nut in sequence from the rear end of the anchor rod body, rotate the nut to squeeze the radial expansion sleeve, so that the radial expansion sleeve expands and squeezes the drill hole to provide initial radial support force;

[0021] Step 3: Install the tray, hydraulic chamber, piston, first spring and locking nut in the outer section of the anchor hole in sequence, raise the control pressure in the one-way return valve to the highest position, use the oil pressure in the hydraulic chamber to provide the maximum support pressure, and then tighten the locking nut to apply a certain preload; due to the different cross-sectional areas of the piston and tray on both sides of the hydraulic chamber, the initially applied preload can be changed proportionally under the action of the hydraulic oil;

[0022] Step 4: When the tunnel surrounding rock is subjected to impact dynamic load, the impact force acts on the tray, and the surrounding rock begins to sink. At this time, the radial support force provided by the radial expansion sleeve plays a role in preventing the surrounding rock from sinking; when the impact dynamic load is large, the surrounding rock continues to move outward. During this process, the anchor body is stretched by the axial force, driving the spring limiter to move toward the hole mouth and compress the second spring to achieve pressure relief. The spring uses its own deformation to effectively consume part of the energy suddenly accumulated inside the surrounding rock, providing buffer time for the hydraulic device to release pressure. At the same time, the arc tray deforms to achieve partial pressure relief, and the entire hydraulic device moves away from the surrounding rock. The piston compresses the hydraulic oil to provide a greater supporting force to prevent the surrounding rock from sinking. When the hydraulic chamber drops to the limit distance, the piston touches the piston limiter, and the piston stops moving. If the impact force continues to increase, the tray tends to expand away from the surrounding rock, and the pressure value of the hydraulic oil exceeds the preset pressure value of the one-way reflux valve. The one-way valve opens, and the hydraulic oil flows out of the one-way valve to prevent damage to the hydraulic device.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention sets pressure-releasing devices with different pressure-releasing mechanisms in the anchoring section, free section and locking section of the anchor rod respectively. According to the change of the impact load of the surrounding rock, the three pressure-releasing devices realize coordinated pressure-releasing. Specifically, the elastic components in the pressure-releasing devices in the anchoring section and the locking section can provide a higher support resistance and provide a buffer time for the pressure-releasing of the hydraulic device. The two cooperate with each other to jointly bear the impact dynamic load of the tunnel surrounding rock; the maximum support resistance can also be adjusted at any time by adjusting the preload force of the one-way return valve; the radial expansion sleeve is set to provide radial support force, and when the impact dynamic load is small, the pressure-releasing device is avoided from being repeatedly started, thereby increasing the service life of the entire system.

[0025] 2. The present invention designs the hydraulic chamber into a trumpet shape, which increases the contact area between the tray and the surface of the surrounding rock, so that under the condition of equal pressure, the force applied to the tray is amplified, thereby increasing the pre-tightening force of the device on the surrounding rock; the multi-stage pressure-relieving device can enable the anchor rod to withstand greater impact force, thereby improving the support force of the device on the deep surrounding rock, especially when the impact is very large and the deep surrounding rock will delaminate. At this time, the second pressure-relieving device plays a more important pressure-relieving role, thereby preventing the anchor rod from being broken.

[0026] 3. The present invention adds a spring pressure-releasing restraint to the periphery of the first spring to prevent the spring from being suddenly compressed and unstable under strong impact dynamic loads, thereby avoiding safety accidents. The spring pressure-releasing restraint also plays a pressure-releasing role to a certain extent, and at the beginning, it also assists the locking nut in applying pre-tightening force. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. The accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0028] Figure 1 It is a schematic diagram of the overall structure of the impact-resistant multi-stage coordinated pressure-yielding anchor rod of the present invention;

[0029] Figure 2 It is a schematic diagram of a one-way reflux valve;

[0030] Figure 3 This is a working state diagram of the impact-resistant multi-stage coordinated pressure-yielding anchor rod of the present invention;

[0031] Figure 4 It is a working diagram of a one-way reflux valve;

[0032] Figure 5 This is the structural diagram of the anchor body.

[0033] In the figure, 1-1: first spring; 1-2: piston; 1-3: piston limiter; 1-4: locking nut; 1-5: filling valve; 1-6: one-way reflux valve; 1-7: tray; 1-8: trumpet-shaped shell; 2-1: second spring; 2-2: spring limiter; 2-3: spring sleeve; 3-1: nut; 3-2: radial expansion sleeve; 3-3: sleeve limiter; 4: anchor rod body; 5: anchoring agent; 6: surrounding rock; 7-1: preload bolt; 7-2: third spring; 7-3: valve shell; 7-4: valve seat; 7-5: valve ball; 7-6: liquid outlet. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0035] Reference Figure 1 As shown, the impact-resistant multi-stage coordinated pressure-releasing anchor provided by the present invention comprises an anchor rod body 4 and three pressure-releasing devices arranged on the anchor rod. The three pressure-releasing devices are respectively distributed in the anchoring section, free section and locking section (i.e., outside the hole) of the anchor rod. For the convenience of description, the three pressure-releasing devices are respectively referred to as the first pressure-releasing device, the radial support device and the second pressure-releasing device. Figure 5It can be seen that the anchor rod body 4 is provided with a sleeve limiter 3-3 and a spring limiter 2-2 in the free section and the anchoring section respectively. The sleeve limiter 3-3 is a dovetail type, and the spring limiter 2-2 is a plate type. In actual processing, the anchor rod and the limiter can be cast into one piece, and then threads are processed on the outer section of the hole and the free section to install the locking nut 1-4 and the nut 3-1.

[0036] The following combination Figure 1 The structures of the first pressure-releasing device, the radial supporting device and the second pressure-releasing device are described in detail. It can be seen from the figure that:

[0037] The first pressure-releasing device is arranged between the locking nut 1-4 of the outer section of the anchor hole and the arc-shaped tray 1-7, and includes a first spring 1-1, a trumpet-shaped shell 1-8, a piston 1-2 and a piston stopper 1-3. The piston 1-2 has a circular hole at its center and is sleeved on the anchor rod body. The diameter of the tray 1-7 is larger than that of the piston 1-2. The open end of the trumpet-shaped shell 1-8 is the tray 1-7, and the locking end of the trumpet-shaped shell 1-8 is the piston 1-2. The piston 1-2, the trumpet-shaped shell 1-8 and the tray 1-7 form a closed cavity as a hydraulic cavity, wherein the piston 1-2 is dynamically sealed with the inner wall of the hydraulic cavity. The piston stopper 1-3 is arranged at the diameter change of the trumpet-shaped shell 1-8. The piston stopper 1-3 is actually two symmetrical stoppers, which are located above and below. The distance that the piston 1-2 moves right in the hydraulic cavity can be limited by the two stoppers, and the volume of the hydraulic cavity can be changed by the distance that the piston 1-2 moves right in the hydraulic cavity. The first spring 1-1 is wound around the anchor rod body, and the left and right ends of the first spring 1-1 are respectively pressed against the locking nut 1-4 and the piston 1-2. In order to prevent the first spring 1-1 from becoming unstable, a telescopic sleeve (not shown in the figure) is arranged around the first spring 1-1. The telescopic sleeve is formed by an inner tube and an outer tube tightly sleeved together, and the contact surface of the two is a rough surface. The inner diameter of the inner tube is required to be adapted to the outer diameter of the spring. The so-called adaptation means that the spring is almost in contact with the inner tube after compression. At this time, the inner tube will not apply resistance to the compression of the spring. At the same time, the outer diameter of the locking nut 1-4 is required to be larger than the outer diameter of the outer tube. At the initial position, the telescopic sleeve is in the longest state. At this time, the outer tube presses against the locking nut 1-4, and the inner tube presses against the piston 1-2. In order to control the oil pressure of the hydraulic chamber and facilitate oil filling, the hydraulic chamber is provided with installation holes for the one-way return valve 1-6 and the filling valve 1-5, and there are rubber rings between all the installation holes and components. The hydraulic chamber is filled with hydraulic oil as a resistance-increasing medium. The hydraulic oil provides support resistance to the tray 1-7 during the movement of the piston 1-2 toward the surrounding rock. When the piston 1-2 touches the piston limiter 1-3, the piston 1-2 stops moving. As the impact load continues to increase, the pressure in the closed container increases. The valve ball 7-5 pushes the valve seat 7-4 to move and compress the third spring 7-2 under the pressure of the hydraulic oil. The one-way return valve 1-6 opens, the hydraulic oil is discharged, and the pressure relief begins. The one-way return valve 1-6 used in the present invention is a commercially available product, such as the one-way return valve mentioned in Chinese patent application publication number CN 110778347A. Its structure and working principle are shown in Figure 2 and Figure 4 ,in Figure 2 Displays the valve closed state, Figure 4The valve is shown in an open state, which is generally composed of a prestressed adjusting bolt 7-1, a third spring 7-2, a valve seat 7-4, a valve ball 7-5, a valve housing 7-3 and a liquid outlet 7-6; the two ends of the spring are respectively connected to the prestressed adjusting bolt 7-1 and the valve seat 7-4. The outer surface of the valve ball 7-5 is wrapped with a layer of rubber, and the total diameter is larger than the diameter of the one-way valve installation hole.

[0038] Reference Figure 1 The second pressure-releasing device of the present invention is arranged at the anchoring section of the anchor rod, and includes a second spring 2-1 and a spring sleeve 2-3. The second spring 2-1, the spring sleeve 2-3 and the spring stopper 2-2 realize pressure-releasing. The spring sleeve 2-3 is a cylinder, and a circular hole with a diameter slightly larger than the diameter of the anchor rod body is opened in the center. The spring sleeve 2-3 is assembled from upper and lower symmetrical parts. The upper and lower parts are buckled on the anchor rod to wrap the spring stopper 2.2 and the front section of the anchor section (the front end of the anchor rod body is exposed to the outside, which is equivalent to a sleeve with only a front cover but no rear cover). The contact surface between the spring sleeve 2-3 and the spring stopper 2-2 is a smooth surface to prevent the spring sleeve 2-3 from causing resistance to the spring stopper; the front section of the spring sleeve 2-3 is a solid structure that is completely attached to the anchor rod body, and the rear end is a hollow structure, and the dividing point between the two is the spring stopper 2-2. The second spring 2-1 is sleeved on the anchor rod body of the hollow structure, one end of the second spring 2-1 is threadedly connected to the spring stopper 2-2 (it can also be in direct contact), and the other end is in direct contact with the spring sleeve wall 2-3. When the second pressure-releasing device of the present invention is working, the circumference of the spring sleeve 2-3 should not generate resistance to the leftward movement of the second spring 2-1 as much as possible, which requires that the outer diameter of the second spring 2-1 when fully compressed is less than or equal to the inner diameter of the spring sleeve wall 2-3.

[0039] Reference Figure 1 The radial support device includes a radial expansion sleeve 3-2 and a nut 3-1. The nut 3-1 is sleeved on the anchor rod body. One end of the radial expansion sleeve 3-2 is pressed against the dovetail of the sleeve limiter 3-3, and the other end is pressed against the nut 3-1. The so-called radial expansion sleeve 3-2 is actually a low-carbon steel sleeve that can undergo plastic deformation under compression. In order to effectively reduce the compression force, at least one pair of axial blind holes or openings can be symmetrically prefabricated in the middle section of the sleeve. This defective radial expansion sleeve 3-2 is like a lantern. When the middle section is squeezed in the middle, it will bulge and form a lantern shape. During construction, by rotating the nut 3-1, the radial expansion sleeve 3-2 moves on the anchor rod body 4 toward the spring limiter 2-2. During the movement, due to the limitation of the sleeve limiter 3-3, the sleeve 3-2 gradually expands and directly contacts the borehole wall. Figure 3The radial expansion sleeve 3-2 is in an expanded state. As can be seen from the figure, the front end of the radial expansion sleeve 3-2 exceeds the inclined surface of the sleeve stopper 3-3 after expansion. Because it is plastically deformed, it will still remain in an expanded state even after passing the inclined surface, thereby generating friction resistance with the surrounding rock. In addition, it is obvious that the radial support device of the present invention needs to be supported on hard rock in order to work.

[0040] According to the following Figure 3 Explanation of the construction and pressure relief mechanism of the present invention

[0041] Step 1: Use an anchor drill to drill a hole in the surrounding rock 6, inject water into the hole to clean the residual coal slag, wind the second spring 2-1 around the front section of the anchor rod body 4, then buckle the upper and lower parts of the spring sleeve 2-3 on the anchor rod, the second spring 2-1 is buckled in the cavity of the spring sleeve 2-3, the front section of the spring sleeve 2-3 is attached to the anchor rod body, calculate the amount of anchoring agent according to the on-site environment, load the required number of resin rolls as anchoring agent 5, start the anchor mixer to push the anchor rod to the bottom of the hole for mixing and anchoring;

[0042] Step 2: Install the radial expansion sleeve 3-2 and the nut 3-1 in sequence from the rear end of the anchor rod, and use a long spanner with an inner hexagon to rotate the nut 3-1 to squeeze the radial expansion sleeve 3-2. After the radial expansion sleeve 3-2 expands, it squeezes the drill hole to provide radial support force. When the nut 3-1 is rotated at the beginning, the right end of the radial expansion sleeve 3-2 is against the inclined surface of the triangle, so a lot of resistance will be generated during the pushing process. When it is pushed to a certain extent, the right end of the radial expansion sleeve 3-2 passes over the inclined surface of the triangle, and the resistance disappears. At this time, the rotation of the nut 3-1 should be stopped. In other words, when it suddenly feels that it becomes easy to rotate the nut 3-1, stop.

[0043] Step 3: Apply a layer of lubricating oil on the exposed anchor rod 4 of the surrounding rock, and install the tray 1-7, trumpet-shaped housing 1-8, piston 1-2, first spring 1-1 and locking nut 1-4 in sequence. The diameter change of the trumpet-shaped housing 1-8 is located at the spring limiter 1-2. Use a hydraulic oil pump to connect the oil filling valve 1-5, raise the preload bolt 7-1 in the one-way return valve 1-6 to the highest position, make the third spring 7-2 in the original position, fill the hydraulic cavity with oil, and when the one-way return valve 1-6 is out of oil, turn off the oil pump, tighten the preload bolt 7-1, set the maximum support pressure, close the oil filling valve 1-5, rotate the locking nut 1-4, and apply a certain preload.

[0044] The working principle of the present invention is: due to the different cross-sectional areas on both sides of the closed container, the preload force applied by the locking nut 1-4 can be proportionally amplified under the transmission of hydraulic oil, so as to achieve the purpose of applying a larger preload force. Assuming the piston area is A1, the tray area is A2, and the force provided by the locking nut 1-4 is F, the preload force acting on the tray is FA2 / A1. When impact dynamic load occurs, the impact force acts on the surrounding rock. When the impact force is small, the radial support force provided by the radial expansion sleeve 3-2 and the sleeve limiter 3-3 extrusion expansion prevents the movement of the surrounding rock. When the impact force is large, the surrounding rock of the tunnel moves outward, the locking nut 1-4 squeezes the first spring 1-1, and the first spring 1-1 is compressed to drive the piston 1-2 to start moving, compressing the hydraulic oil and providing a larger support force. At the same time, due to the ductility of the anchor rod body 4 itself, the anchor rod body 4 is stretched and extended, driving the spring limiter 2-2 to compress the second spring 2-1, converting part of the impact energy into the elastic energy of the spring, and at the same time buffering the impact dynamic load to provide a buffer for the start of the hydraulic device. When the piston 1-2 touches the piston limiter 1-3, the piston 1-2 stops moving. When the pressure in the hydraulic chamber is greater than the set initial value, the one-way return valve opens and starts to relieve pressure to protect the entire support system.

[0045] The above is only an embodiment of the present invention and is not intended to limit the technical solution of the present invention. For example, the relationship between the outer diameter of the first spring 1-1 and the inner diameter of the telescopic sleeve, and the relationship between the outer diameter of the second spring 2-1 and the inner diameter of the spring sleeve 2-3 in the embodiment can be adjusted according to the site and actual needs. However, a principle must be followed that the inner wall of the sleeve cannot provide resistance to the compression of the spring. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. An impact-resistant multi-stage coordinated pressure-yielding anchor rod, comprising an anchor rod body, a tray and a nut, characterized in that: The invention comprises a first pressure-releasing device arranged at the rear section of the anchor rod body, a second pressure-releasing device arranged at the front section of the anchor rod body and a radial supporting device arranged at the free section of the anchor rod body, wherein: The front section and the free section of the anchor rod body are both provided with limiters, which are respectively called spring limiters and sleeve limiters. The limiters and the anchor rod body are an integrated structure. The anchor rod body behind the sleeve limiter and the part of the anchor rod body where the locking nut is installed are both provided with threads. The first pressure-releasing device is arranged between the tray and the nut, and includes a trumpet-shaped shell, a piston sleeved on the anchor rod body, and a first spring. The closed end of the trumpet-shaped shell is the piston, and the open end is the tray. The piston, the tray, and the trumpet-shaped shell form a closed cavity as a hydraulic cavity, and a limiter is provided at the diameter-changing part in the closed cavity; the first spring is sleeved on the anchor rod, one end of the first spring presses on the locking nut, and the other end presses on the piston, and a one-way reflux valve and a filling valve are provided on the hydraulic cavity; The second pressure-releasing device includes a spring sleeve and a second spring. The spring sleeve is sleeved on the front section of the anchor rod body and wraps the spring limiter inside. The front section of the spring sleeve is a solid structure wrapped around the circumference of the anchor rod body, and the rear end is a hollow cavity structure. The dividing point between the two is the spring limiter. The second spring is sleeved in the hollow structure and sleeved on the anchor rod body; that is, the left and right ends of the second spring are respectively pressed against the spring limiter and the spring sleeve, and the second spring is arranged in the hollow cavity of the spring sleeve. When the spring sleeve is compressed, it is not affected by the inner wall of the spring sleeve; The radial support device comprises a steel radial expansion sleeve and a nut capable of plastic deformation. The nut is sleeved on the anchor rod body, the radial expansion sleeve is arranged around the anchor rod body, one end of the radial expansion sleeve is pressed against the sleeve limiter and the other end is pressed against the nut.

2. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 1, characterized in that: A spring compression restraint is arranged on the periphery of the first spring, and the spring compression restraint can not only limit the vertical displacement of the spring but also shrink as the spring is compressed.

3. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 2 is characterized in that: The spring compression restraint member is a two-stage telescopic sleeve, which is formed by an inner and outer tube sleeved together. The contact surface of the inner and outer tubes is a rough surface. The inner diameter of the inner tube is required to be adapted to the outer diameter of the spring. At this time, the outer diameter of the nut is larger than the outer diameter of the outer tube.

4. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 1, characterized in that: The spring sleeve is formed by buckling the upper and lower parts together.

5. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 1, characterized in that: The anchor rod body and the stopper are cast into one piece by steel, and then threads are processed on the anchor rod body behind the sleeve stopper and on which the locking nut is installed.

6. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 1, characterized in that: The center mounting holes on the tray and the piston are provided with rubber sealing rings to prevent the hydraulic oil from leaking out.

7. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 1, characterized in that: The steel radial expansion sleeve has axial prefabrication defects.

8. The impact-resistant multi-stage coordinated pressure-yielding anchor rod according to claim 7, characterized in that: The defective structure is that axial blind holes or openings are symmetrically arranged around the middle section of the plastic sleeve.

9. A method for realizing the impact-resistant multi-stage coordinated pressure-yielding anchor rod according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Drill a hole on the rock to be supported as required, assemble the second pressure-releasing device and the anchor rod body outside the hole, then start the anchor mixer to push the anchor rod to the bottom of the hole, and use the anchor agent to anchor the entire spring sleeve and the front end of the anchor rod to the surrounding rock; Step 2: Install the radial expansion sleeve and nut in sequence from the rear end of the anchor rod body, rotate the nut to squeeze the radial expansion sleeve, so that the radial expansion sleeve expands and squeezes the drill hole to provide initial radial support force; Step 3: Install the tray, hydraulic chamber, piston, first spring and locking nut in the outer section of the anchor rod hole in sequence, raise the control pressure in the one-way return valve to the highest position, use the oil pressure in the hydraulic chamber to provide the maximum support pressure, and then tighten the locking nut to apply a certain preload; due to the different cross-sectional areas of the piston and tray on both sides of the hydraulic chamber, the initially applied preload can be changed proportionally under the action of the hydraulic oil; Step 4: When the tunnel surrounding rock is subjected to impact dynamic load, the impact force acts on the tray, and the surrounding rock begins to sink. At this time, the radial support force provided by the radial expansion sleeve plays a role in preventing the surrounding rock from sinking; when the impact dynamic load is large, the surrounding rock continues to move outward. During this process, the anchor rod body is stretched by the axial force, driving the spring limiter to move toward the hole mouth to compress the second spring to achieve pressure relief. The spring uses its own deformation to effectively consume part of the energy suddenly accumulated inside the surrounding rock, providing buffer time for the hydraulic device to release pressure. At the same time, the arc tray deforms to achieve partial pressure relief, and the entire hydraulic device moves away from the surrounding rock. The movement trend forces the locking nut to compress the first spring. When the first spring is compressed to the limit, under the obstruction of the locking nut, as the hydraulic chamber descends, its volume gradually decreases, the pressure of the hydraulic oil increases, and the supporting force that can be provided increases, that is, the piston compresses the hydraulic oil to provide a greater supporting force to prevent the surrounding rock from sinking; when the hydraulic chamber descends to the limit distance, that is, when the piston touches the piston limiter, the piston stops moving; if the impact force continues to increase, the tray tends to expand away from the surrounding rock, the pressure value of the hydraulic oil exceeds the preset pressure value of the one-way reflux valve, the one-way valve opens, and the hydraulic oil flows out of the one-way valve to prevent damage to the hydraulic device.

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