CN110966030B

CN110966030B - Extensible anchor rod and recoverable anchor rod device with multistage stress and displacement control

Info

Publication number: CN110966030B
Application number: CN201911258966.4A
Authority: CN
Inventors: 张兴胜; 李倩倩; 周进; 黄志全; 董金玉; 刘时鹏; 于怀昌; 陈上元; 王洪建; 刘欣宇; 宋午阳
Original assignee: North China University of Water Resources and Electric Power
Current assignee: North China University of Water Resources and Electric Power
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2021-09-10
Anticipated expiration: 2039-12-10
Also published as: CN110966030A

Abstract

The invention provides an extensible anchor rod and a recoverable anchor rod device with multistage stress and displacement control, and overcomes the defect that a rigid anchor rod in the prior art cannot adapt to the displacement and stress control of a rock and soil mass in a large range. The anchor rod has the recoverable effect. The scheme is that the pipe comprises a sleeve, the sleeve comprises a plurality of sections of pipes which are arranged at intervals, the lower end of the pipe at the lowest end is connected with a base, a tray is fixed at the upper end of the pipe at the highest end, a stressed elastic body and a specific yielding stress stretching resistant body are connected between the circumferential end faces of every two adjacent pipes, the bottom end of the base is connected with a connecting column, the bottom end of the connecting column can be detached and connected with an anchoring section, a through hole is formed in the center of the tray, a screw rod which is arranged in the sleeve and coaxial with the sleeve is fixed on the base, the other end of the screw rod penetrates out through the through hole, and a nut is screwed on the part of the screw rod which penetrates out.

Description

Extensible anchor rod and recoverable anchor rod device with multistage stress and displacement control

Technical Field

The invention relates to an anchor rod, in particular to an extensible anchor rod and a recoverable anchor rod device with multistage stress and displacement control.

Background

The anchor rod is widely applied to geotechnical engineering, and the anchor rod reinforcement is commonly used in projects such as side slopes, foundation pits, tunnels, roadways, urban underground spaces and the like, and is also commonly used in underground deep mines and energy mining. The anchor rod can actively reinforce the rock-soil body, can make the rock-soil body give full play to its self stability, effectively control the deformation of the rock-soil body, furthest keeps the integrity of the surrounding rock, and prevents the damage of the whole collapse of the rock-soil body. Meanwhile, the anchor rod has the important characteristics of less damage to the original rock-soil body, small disturbance, easy construction, economy, safety and environmental protection.

Under the high stress condition of surrounding rocks, particularly in soft rock areas, the large deformation characteristic is often shown under the action of external loading and unloading load, vibration impact and the like. Most of the anchor rods in the prior art directly anchor one end of each anchor rod in a rock mass at the bottom of each anchor hole, and the other end of each anchor rod is anchored on the outer side surface of the side slope. The anchor rod has smaller ultimate stretching length, and when the surrounding rock is greatly deformed, the common anchor rod cannot meet the requirements of engineering safety to adapt to the larger deformation of the surrounding rock, so that the phenomena of anchor head failure, anchor rod breakage and the like are frequently caused, the anchoring effect of the anchor rod is lost, and further engineering accidents are caused.

The utility model discloses a from flexible big deformation stock, patent number is 201621376559.5, and the flexible volume of stock of this patent is L, and its deflection is mainly undertaken by spring and stock two parts, and this kind of structure still waits to update perfect (still has the defect), and this utility model mainly has following not enoughly: firstly, if the load bearing or load increase occurs in the actual engineering, and the allowable deformation amount is smaller, it becomes difficult to continue to increase the load bearing capacity of the anchor rod under such working conditions, for example, it is extremely difficult to replace or increase the strength of the spring 4, just as in paragraph 0014, the anchor rod and the piston are in an integral structure. Secondly, if in actual engineering, because the bearing or load increase, and the deformation that has allowed is great, because the bearing capacity maximum value of stock is certain under this kind of operating mode, when the deformation that allows is greater than the stock maximum deformation of original design, if again increase spring 4 maximum elongation is equally difficult, just as in 0014 section the stock and piston are integrative structure.

The existing anchor rod is generally abandoned in the anchor hole after the use is finished, and the existing anchor rod cannot be recycled, so that the waste is caused to the use of the anchor rod.

Disclosure of Invention

In view of the above situation, in order to overcome the defects of the prior art, the invention provides a multistage stress and displacement control extensible anchor rod and a recoverable anchor rod device, which can effectively overcome the defect that a rigid anchor rod in the prior art cannot adapt to the displacement and stress control of a rock-soil body in a large range, and a self-telescopic large-deformation anchor rod in the background art cannot control a slope in a grading manner, mainly adopts elastic control, and has insufficient adaptability to the subsequent stress increase or deformation control change of the actual rock-soil body. The anchor rod has the recoverable effect.

The technical scheme of its solution is, including the sleeve pipe, the sleeve pipe includes the body of multisection interval arrangement, and the body lower extreme of lower extreme is connected with the base, and the body upper end of top is fixed with the tray, is connected with atress elastomer and specific yield stress stretching resistance body between the circumference terminal surface of per two adjacent bodies, the base bottom is connected with the spliced pole, the spliced pole bottom can be dismantled and be connected with the anchor section, the tray center is equipped with the through-hole, be fixed with on the base and arrange in the sleeve pipe with the coaxial screw rod of sleeve pipe, the other end of screw rod is worn out through the through-hole, the partial top spin of wearing out of screw rod has twisted the nut.

Preferably, the number of the stressed elastic bodies and the specific yield stress stretching-resistant body are both multiple.

Preferably, the number of the stressed elastic bodies is the same as that of the specific yielding tensile bodies, the specific yielding tensile bodies are uniformly arranged between the two pipe bodies at intervals, and the stressed elastic bodies are sleeved on the specific yielding tensile bodies.

Preferably, the stressed elastomer is sleeved with a sleeve at intervals.

Preferably, a first telescopic cylinder is sleeved outside the stress elastic body at intervals, and two ends of the first telescopic cylinder are connected between two adjacent pipe bodies.

Preferably, the pipe joint further comprises a second telescopic cylinder, the second telescopic cylinder is connected between two adjacent pipe bodies, and the stressed elastic body and the specific yielding stress tensile body are both arranged in the second telescopic cylinder.

Preferably, a through hole is formed in the center of the tray, a screw rod which is arranged in the sleeve and coaxial with the sleeve is fixed on the base, the other end of the screw rod penetrates out of the through hole, and a nut is screwed on the penetrating part of the screw rod.

Preferably, a compression backing plate is sleeved on the screw rod between the nut and the tray.

Preferably, a centering support is fixed in the pipe body, a central hole coaxial with the sleeve is formed in the center of the centering support, and the screw penetrates through the central hole of the centering support.

Preferably, the stressed elastic body is a spring, and the specific yielding tensile body is a steel strand.

Preferably, the bottom end of the connecting column is provided with an annular groove, the top of the anchoring section protrudes upwards to form an annular protrusion matched with the annular groove, and the annular protrusion is detachably connected with the annular groove.

Preferably, the top end of the anchoring section in the annular bulge is provided with a compression spring groove, the center position of the bottom end of the connecting column is downwards protruded with a compression spring seat corresponding to the compression spring groove, and a compression spring is arranged on the compression spring seat.

Preferably, the inner circular surface of the annular protrusion is provided with an internal thread, the inner circular surface of the annular groove is provided with an external thread matched with the internal thread, and the annular protrusion and the annular groove are in threaded fit to form detachable connection.

Preferably, the left side and the right side of the bottom end of the connecting column are respectively provided with a sliding groove communicated with the annular groove, the upper end of the sliding groove is connected with an arc-shaped groove, the left side and the right side of the top end of the annular bulge are respectively fixed with a sliding block matched with the sliding groove, and the sliding block slides into the arc-shaped groove through the sliding groove to form a detachable structure.

The invention can allow the rock-soil mass to be reinforced to have a certain deformation amount, can set a certain limit value for the displacement of the rock-soil mass to be reinforced, changes the stress state of the rock-soil mass through the anchoring effect so as to realize the displacement control of the rock-soil mass, and allows the rock-soil mass to generate a certain displacement amount value within the engineering safety allowable range when the stress borne by the anchor rod body exceeds a certain designed value. The invention can form a sleeve by a plurality of pipe bodies, carry out first-level two-stage control on a rock-soil body to be reinforced by the stressed elastic bodies and the specific yielding tensile bodies between two adjacent pipe bodies, carry out second-level multi-stage control by the difference of the yield stress of the specific yielding tensile bodies in the multi-section first-level control, and carry out third-level multi-stage control by setting the distance between the nuts and the trays so as to control the maximum displacement of the rock-soil body to be reinforced. The invention provides two specific structures of the recyclable anchor rod, so that the anchor rod can be recycled when in use, the use of materials is effectively saved, and the cost is reduced.

Drawings

FIG. 1 is a front view of the present invention.

Fig. 2 is a front view of the present invention (with the connecting post and anchoring section removed).

Fig. 3 is a perspective view of the view of fig. 2 (with the connecting posts and anchoring segments removed).

Fig. 4 is an enlarged view of a portion B in fig. 3.

Fig. 5 is a perspective view in section of the view of fig. 2 (with the connecting post and anchor segments removed).

Fig. 6 is a front view of the present invention with the sleeve applied (with the connecting post and anchor segment removed).

Fig. 7 is a perspective view of the present invention with the first telescoping cylinder added (with the connecting post and anchoring section removed).

Fig. 8 is a perspective cross-sectional view of the present invention with the first telescoping cylinder added (with the connecting post and anchoring section removed).

Fig. 9 is a perspective sectional view of the inner structure of the first telescopic cylinder in fig. 8.

Fig. 10 is a perspective view of the present invention with a second telescoping cylinder added (with the connecting post and anchoring section removed).

Fig. 11 is a perspective cross-sectional view of the present invention with a second telescoping cylinder added (with the connecting post and anchoring section removed).

Fig. 12 is a sectional view of a first telescopic cylinder of the present invention.

Fig. 13 is a sectional view of a second telescopic cylinder of the present invention.

Fig. 14 is a perspective view of a centering bracket of the present invention.

Fig. 15 is a structural view of the present invention installed in an anchor eye.

Fig. 16 is a block diagram of a threaded connection between an anchor segment and a connecting post according to the present invention.

Fig. 17 is a front view of the connection between the anchor segments and the connecting studs of the present invention.

FIG. 18 is a cross-sectional view of the connection between the anchor segment and the connecting stud via the annular groove and the slider of the present invention.

FIG. 19 is a two-section view of the anchor segment and connecting post connected via an annular groove and a slider of the present invention.

FIG. 20 is a perspective view of a connector block of the present invention connected between an anchor segment and a connector post via an annular groove and a slider.

Figure 21 is a perspective view in section of figure 20.

Fig. 22 is a perspective view of an anchor segment connected to a connecting post via an annular groove and a slider according to the present invention.

Detailed Description

The following description of the present invention will be made in further detail with reference to the accompanying fig. 1 to 22.

The technical scheme includes that the sleeve 1 comprises a plurality of sections of pipe bodies 2 which are arranged at intervals, a base 3 is connected to the bottom end of the pipe body 2 at the lowest end, a tray 4 is fixed to the top end of the pipe body 2 at the highest end, a stressed elastic body 5 and a specific yielding stress stretching-resistant body 6 are connected between the circumferential end faces of every two adjacent pipe bodies 2, a connecting column 16 is connected to the bottom end of the base 3, an anchoring section 17 is detachably connected to the bottom end of the connecting column 16, a through hole is formed in the center of the tray 4, a screw rod 12 which is arranged in the sleeve 1 and coaxial with the sleeve 1 is fixed to the base 3, the other end of the screw rod 12 penetrates out through the through hole, and a nut 13 is screwed to the penetrating part of the screw rod 12. The anchoring section is a stepped shaft with a diameter smaller at the lower part and a larger diameter smaller at the upper part, so that the anchoring is firmer. The arrangement is such that the anchor rods other than the anchor segments can be separated from the anchor segments and then recycled.

When the embodiment is used, as shown in fig. 1 to 5, because there are a plurality of pipe bodies 2, there are also a plurality of intervals between the plurality of pipe bodies 2, a displacement control part is arranged between every two pipe bodies 2, the displacement control part comprises a stressed elastic body 5 and a specific yield tensile body 6, the yield strength of the specific yield tensile body 6 in each layer of the displacement control part is different, and preferably, the yield strength of the specific yield tensile body 6 from bottom to top is gradually increased. The stressed elastic body 5 can be a spring, and the specific yielding stretching-resistant body 6 can be a steel strand. When the anchor is used specifically, slurry is injected between the anchoring section 17 and the anchor hole 7 to anchor the anchoring section 17, and the side surface of the tray 4 is attached to a rock-soil body to be reinforced. When the rock and soil mass to be reinforced has a smaller displacement trend, the specific yielding tension-resistant body 6 generates stress through the tray 4, and when the specific yielding tension-resistant body 6 does not reach the yield strength, the displacement of the whole rock and soil mass to be reinforced under the control of the anchor rod is extremely small; when the stress borne by the anchor rod continues to increase, the specific yielding tension resistant body 6 with the minimum yield strength reaches the yield strength, the specific yielding tension resistant body 6 reaching the yield strength fails, the stressed elastic body 5 matched with the failed specific yielding tension resistant body 6 starts to work, and the displacement deformation of the rock-soil body to be reinforced is controlled through the elastic tension of the stressed elastic body. When the stress continues to increase, the specific yielding tensile body 6 with the second level of yield strength reaches a yielding state, the specific yielding tensile body 6 with the second level of yield strength fails, and the stressed elastic body 5 matched with the specific yielding tensile body controls the displacement deformation amount of the rock-soil body to be reinforced through the tensile force of the stressed elastic body. And when the displacement of the added rock-soil mass continues to increase, the next-level displacement control component continues to work. By means of design, when the total range of the stressed elastic body of the previous level reaches 30%, the specific yielding stress tensile body 6 of the next level reaches the yield strength and fails successively.

In the embodiment 1, two-stage displacement control is performed through the specific yielding stress tensile body 6 and the stress elastic body 5 in each layer of displacement control component, and multi-stage displacement control is performed through the multi-stage displacement control component.

In the embodiment, a screw 12 is fixed on the center of a base 3, through holes are extended from the upper end of the screw 12 at intervals, a nut 13 is screwed on the screw 12, a certain distance is set between the nut 13 and a tray 4 during initial setting, after the multistage displacement control component works, if the maximum deformation allowed by a side slope is reached, the nut 13 contacts the tray 4 at the moment, active control is carried out on a rock-soil body to be reinforced by the rigid screw 12, the screw 12 at the moment is equivalent to a rigid anchor rod in the background technology, and after the screw 12 and the nut 13 are added, one-stage control is added for controlling the deformation and the stress of the rock-soil body to be reinforced. And the displacement of the slope is controlled within a controllable range by controlling the interval between the nut 13 and the tray 4. The screw rod in the invention can be replaced by a steel strand. And the extending end at the upper end of the steel strand is matched with the nut in a threaded manner. The maximum displacement deformation amount allowed by the required reinforced rock-soil body can be adjusted through the nut.

Example 2, on the basis of example 1, the number of the stressed elastic bodies 5 and the specific yield stress tensile body 6 are both multiple. The number of the stress elastic bodies 5 and the specific yield stress tensile bodies 6 can be more than three, and the stress elastic bodies and the specific yield stress tensile bodies are evenly distributed between the two pipe bodies 2 at intervals on the circumference.

Example 3, on the basis of example 2, the number of the stressed elastic bodies 5 is the same as that of the specific yielding tensile bodies 6, the specific yielding tensile bodies 6 are uniformly arranged between the two pipe bodies 2 at intervals, and the stressed elastic bodies 5 are sleeved on the specific yielding tensile bodies 6. The stress elastic body 5 is sleeved on the specific yield stress tensile body 6, so that the space between the pipe bodies 2 is saved, and the design is more regular.

Example 4, on the basis of example 3, the stressed elastomer 5 is sleeved with a sleeve 8 at an interval.

As shown in fig. 6, the upper and lower ends of the sleeve 8 can be welded to the upper and lower pipes 2 by spot welding, and when the stress is large, the upper and lower multiple spot welding is broken first, and then the multi-stage specific yield tensile member 6 reaches the yield strength and fails. This allows the bushing 1 to protect the stressed elastomer 5 and the specific yield tensile member 6 within the bushing 1 during installation.

In embodiment 5, on the basis of embodiment 3, a first telescopic cylinder 9 is sleeved outside the stressed elastic body 5 at intervals, and two ends of the first telescopic cylinder 9 are connected between two adjacent pipe bodies 2.

In this embodiment, the first telescopic cylinder 9 is sleeved on the stressed elastic body 5, so that the stressed elastic body 5 and the specific yield stress tensile body 6 are protected. And the first telescopic cylinder 9 has the elasticity, and does not influence the work of the stressed elastic body 5 and the specific yielding stress tensile body 6. The first telescopic cylinder 9 is composed of a large telescopic cylinder and a small telescopic cylinder which is arranged in the large telescopic cylinder in a sliding and penetrating mode.

Embodiment 6, on the basis of embodiment 3, as shown in fig. 10, 11 and 13, further includes a second telescopic tube 10, where the second telescopic tube 10 is connected between two adjacent tubes 2, and the stressed elastomer 5 and the specific yield tensile resistance body 6 are both disposed in the second telescopic tube 10. The second telescopic cylinder 10 is composed of a large telescopic cylinder and a small telescopic cylinder which is slidably arranged in the large telescopic cylinder in a penetrating mode, the upper portion of the small telescopic cylinder is fixedly sleeved on the outer circular surface of the corresponding pipe body, the lower end of the large telescopic cylinder is connected with a connecting ring 11 which extends inwards, and the inner circular surface of the connecting ring 11 is fixedly sleeved on the outer circular surface of the corresponding pipe body.

In the embodiment, all the stressed elastic bodies 5 and the specific yielding tension-resistant bodies 6 between two connected pipe bodies 2 are arranged in the same large telescopic cylinder 10, and the telescopic cylinder 10 can protect the stressed elastic bodies 5 and the specific yielding tension-resistant bodies 6 without influencing the work of the stressed elastic bodies 5 and the specific yielding tension-resistant bodies 6.

Embodiment 7 is characterized in that a pressure bearing plate 14 is sleeved on the screw 12 between the nut 13 and the tray 4 on the basis of embodiment 1.

In this embodiment, a pressure pad 14 is added, and the pressure pad 14 is added between the nut 13 and the tray 4, so that the nut 13 is pressed on the pressure pad 14 first and is pressed on the tray 4 through the pressure pad 14, thereby protecting the tray 4.

Embodiment 8 is based on embodiment 1, a centering bracket 15 is fixed in the tube body 2, a center hole coaxial with the sleeve 1 is formed in the center of the centering bracket 15, and the screw 12 penetrates through the center hole of the centering bracket 15.

The bracket 15 is centered so that the bolt is centered in the sleeve 1 and serves to stabilize and support the screw 12 and prevent the screw 12 from shifting. The screw rod and the centering bracket can slide.

Example 9, based on any of examples 1-8, the stressed elastomer 5 is a spring and the specific yield tensile member 6 is a steel strand.

In the embodiment 10, on the basis of the embodiment 1, the bottom end of the connecting column 16 is provided with an annular groove 18, the top of the anchoring section 17 is provided with an annular protrusion 19 which is matched with the annular groove 18 in an upward protruding mode, and the annular protrusion 19 is detachably connected with the annular groove 18. The annular protrusion 19 is disposed in the annular groove 18, and the bottom end of the connecting post 16 and the top end of the anchoring section 17 can be attached to each other after the engagement is completed.

In the embodiment 11, on the basis of the embodiment 10, the top end of the anchoring section 17 in the annular protrusion 19 is provided with a compression spring groove 20, the center position of the bottom end of the connecting column 16 is protruded downwards with a compression spring seat 21 corresponding to the compression spring groove 20, and the compression spring seat 21 is provided with a compression spring 22. A pressure spring 22 is arranged between the anchoring section 17 and the connecting column 16, so that prestress is added between the anchoring section and the connecting column, and the position state matching of the anchoring section and the connecting column is firmer. The top end of the pressure spring 22 is fixed at the bottom end of the connecting column 16, and the pressure spring seat 21 is positioned at the center of the pressure spring 22.

Embodiment 12 is based on embodiment 11, the inner circumferential surface of the annular protrusion 19 is provided with an internal thread, the inner circumferential surface of the annular groove 18 is provided with an external thread matched with the internal thread, and the annular protrusion 19 and the annular groove 18 form a detachable connection through thread matching. When the embodiment is used, the annular protrusion 19 is screwed into the annular groove 18 through thread fit, the pressure spring 22 is compressed in the screwing process, prestress is formed between the thread fit due to the compression of the pressure spring 22, the friction force between the thread fit is increased, and the thread fit is firmer. Then the device is placed in the anchor hole 7, and grout is injected between the anchor hole 7 and the anchoring section 17 to anchor the anchor. When the connecting column 16 and the anchor rod on the upper part of the connecting column need to be removed, the base 3 is screwed reversely through the screw 12, and the base 3 carries the connecting column 16 to be screwed off the anchoring section 17 to form separation.

Embodiment 13 on the basis of embodiment 11, the left and right sides of the bottom end of the connecting column 16 are respectively provided with a sliding chute 23 communicated with the annular groove 18, the upper end of the sliding chute 23 is connected with an arc-shaped groove 24, the left and right sides of the top end of the annular protrusion 19 are respectively fixed with a sliding block 25 matched with the sliding chute 23, and the sliding block 25 slides into the arc-shaped groove 24 through the sliding chute 23 to form a detachable structure.

When the anchoring section 17 and the connecting column 16 need to be connected together, the sliding block 25 slides into the top of the sliding groove 23, then the anchoring section 17 is rotated, the sliding block 25 slides into the arc-shaped groove 24, under the pressure of the pressure spring 20, the anchoring section 17 and the connecting column 16 tend to be away from each other, and at the moment, the bottom end of the sliding block 25 contacts the bottom surface of the arc-shaped groove 24, so that the connecting column 16 and the anchoring section 17 cannot be separated from each other, and the two are connected together. The invention is then placed into the anchor eye 7 and grout is injected between the anchor eye 7 and the anchor section 17 so that the anchor section 17 is anchored. When the separation is needed, the base 3 is rotated through the screw rod 2, the base 3 drives the connecting column 16 to rotate, the arc-shaped groove 24 on the connecting column 16 rotates relative to the sliding block 25, when the sliding block 25 is rotated to the position of the sliding groove 23, the screw rod 12 is pulled upwards, and the upper part of the anchor rod is taken out to form the separation.

Claims

1. A multi-stage stress and displacement control extensible and recyclable anchor rod is characterized by comprising a sleeve (1), the sleeve (1) comprises a plurality of sections of pipe bodies (2) which are arranged at intervals, the lower end of the pipe body (2) at the lowest end is connected with a base (3), a tray (4) is fixed at the upper end of the pipe body (2) at the highest end, a stressed elastic body (5) and a specific yielding stress tensile body (6) are connected between the circumferential end surfaces of every two adjacent pipe bodies (2), the bottom end of the base (3) is connected with a connecting column (16), the bottom end of the connecting column (16) is detachably connected with an anchoring section (17), a through hole is arranged at the center of the tray (4), a screw rod (12) which is arranged in the sleeve (1) and has the same axle center with the sleeve (1) is fixed on the base (3), the other end of the screw rod (12) penetrates out through the through hole, and a nut (13) is screwed on the penetrating part of the screw rod (12);

the side surface of the tray (4) is attached to a rock-soil body to be reinforced;

the number of the stressed elastic bodies (5) and the number of the specific yielding stress tensile bodies (6) are both multiple, and the yield strength of the specific yielding stress tensile bodies (6) from bottom to top is gradually increased.

2. A multistage stress and displacement controlled elongation and recovery anchor according to claim 1, characterised in that the number of said stress-elastic bodies (5) and specific yielding tension-resistant bodies (6) is the same, said specific yielding tension-resistant bodies (6) are evenly spaced between two tubular bodies (2), and said stress-elastic bodies (5) are sleeved on said specific yielding tension-resistant bodies (6).

3. The multi-stage stress and displacement controlled extensible and retrievable anchor according to claim 2, wherein the stressed elastomer (5) is externally spaced by a sleeve (8).

4. The multi-stage stress and displacement control extensible and recoverable anchor rod according to claim 2, wherein the stressed elastic body (5) is sleeved with a first telescopic cylinder (9) at intervals, and two ends of the first telescopic cylinder (9) are connected between two adjacent pipe bodies (2).

5. A multi-stage stress and displacement controlled extendible and retrievable rock bolt according to claim 2, further comprising a second telescopic tube (10), said second telescopic tube (10) being connected between two adjacent tubes (2), said stressed elastomer (5) and said specific yield tensile member (6) being disposed within the second telescopic tube (10).

6. A multi-stage stress and displacement controlled extendible and retrievable rock bolt according to claim 1, wherein the screw (12) between the nut (13) and the tray (4) is fitted with a compression pad (14).

7. A multi-stage stress and displacement controlled extendible and retrievable rock bolt according to claim 1, wherein a centering bracket (15) is fixed inside the tubular body (2), the centering bracket (15) having a central hole coaxial with the sleeve (1) at the center, the screw (12) passing through the central hole of the centering bracket (15).

8. A multistage stress and displacement control extensible and recoverable anchor rod according to any one of claims 1 to 7, wherein said stressed elastomer (5) is a spring and said specific yield tensile (6) is a steel strand.

9. The multi-stage stress and displacement control extensible and recyclable anchor rod as claimed in claim 1, wherein the bottom end of the connecting column (16) is provided with an annular groove (18), the top of the anchoring section (17) is provided with an annular protrusion (19) which is matched with the annular groove (18) in a protruding manner, and the annular protrusion (19) is detachably connected with the annular groove (18).