End-expanded anchor rod and construction method thereof

Abstract

The present invention discloses an end-expanded anchor rod and a construction method thereof, which belongs to the field of anchoring technology, and includes an anchor rod body, a No. 1 clamping mechanism, a bladder, a locking plug, a No. 1 support rod, a No. 2 support rod, a No. 3 support rod, a grouting pipe, a casing, a grouting channel, an end plate, a No. 2 clamping mechanism, a sliding sleeve, a smooth pipe, and a jacking plate; the No. 1 clamping mechanism includes a mechanism body, a locking buckle, a sealing rubber ring, a ball valve, a support guide, a grouting channel, a clamping plug, and a clamping spring; the construction steps of the expanded anchor rod are as follows: preliminary test, drilling construction, lowering the anchor rod, bladder grouting, prestressing tensioning, and construction completion. The present invention applies the main force to the support rod by the slurry pressure, thereby ensuring the reliability of the full deployment of the bladder; by setting a plurality of support rods, the strength of the anchor body itself is strengthened; by using a rigid material for the bladder, the squeezing and expanding effect of the bladder on the surrounding soil is strengthened.

Description

Technical Field

[0001] The invention relates to the technical field of anchoring, and in particular to an end-expanded anchor rod and a construction method thereof. Background Art

[0002] As the intensity and depth of underground engineering development increase, deep foundation pit support has become a problem that restricts the efficient and safe construction of high-rise buildings. After the foundation pit is excavated, it is easy to cause large deformation of the side walls and soil slopes of the foundation pit, and the support structure will fail. The safety of underground engineering is becoming more and more important. Traditional anchor rods have been widely used in water conservancy and hydropower, civil engineering, transportation, municipal engineering and other projects.

[0003] Traditional friction anchors rely on the bonding force and friction effect of the anchoring section on the surrounding soil to transmit force loads, and the magnitude of the anchoring force depends on the length of the effective anchoring section. The bag-type expanded anchor is a friction-end bearing anchor. When in use, cement slurry is injected into the bag through a high-pressure pump. After the bag expands, it forms a cement body of the expanded section under the compression of the surrounding soil layer. Therefore, the bag-type expanded anchor not only resists buoyancy through the friction resistance of the expanded section side wall and its bonding force with the surrounding soil, but also resists buoyancy through the end resistance provided by the compression of the expanded section end. Compared with traditional anchors, the bag-type expanded anchor has the advantages of high single anchor bearing capacity, short length, small number, high economic and environmental benefits. However, in the process of using anchor support, the problem of anchor end failure has become increasingly prominent. Once the anchor end fails, the anchor cannot play a substantial role, and the safety of foundation pit construction is seriously threatened.

[0004] At present, the capsule anchor used in underground engineering and slope reinforcement projects mainly relies on the bonding force, friction and end bearing force between the anchor section and the surrounding soil to transfer the load. Its main disadvantages are: (1) The magnitude of the anchoring force depends on the length and diameter of the anchor section, as well as the nature of the soil in contact with the anchor section. If a special weak soil is encountered, the pull-out force of the anchor is not high, and the reinforcement effect is not good; (2) Ordinary capsule anchors have the problem of small contact area between cement and the anchor body, and poor grip between the anchor body and the anchor body. Therefore, the present invention proposes an end-expanded anchor and its construction method to solve the above problems. Summary of the invention

[0005] In view of the above technical problems existing in the prior art, the present invention proposes an end-expanded anchor rod and its construction method, which overcomes the shortcomings of the prior art. The main force is applied to the support rod by the slurry pressure, and the high-pressure slurry fills the bladder, which ensures the reliability of the bladder fully unfolding; by setting up multiple support rods, the strength of the anchor body itself is strengthened to ensure that the anchor body itself will not be broken during operation; by using rigid materials for the bladder, the squeezing and expanding effect of the bladder on the surrounding soil is strengthened, so that the mechanical properties of the surrounding soil are better.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The bolt has a locking mechanism, a locking ring, a sealing ring, a ball valve, a support guide, a grouting channel, a locking plug, and a locking spring. The bolt has a smooth tube welded to the outside of the bolt body, and the smooth tube is connected to the sliding sleeve by welding. The No. 2 locking mechanism comprises a mechanism main body, a locking ring, a grouting channel, and a bite cavity. The grouting tube passes through the sliding sleeve and is welded on the sliding sleeve. The No. 1 locking mechanism is installed in the sliding sleeve, and sealing rings are installed between the No. 1 locking mechanism and the sliding sleeve and the smooth tube. One end of the bladder is connected to the locking ring of the No. 1 locking structure, and the other end of the bladder is connected to the locking ring of the No. 2 locking structure. The first support rod is connected to the first clamping mechanism by a hinge, the first support rod is connected to the second support rod by a hinge, the second support rod is connected to the third support rod by a hinge, the third support rod is connected to the second clamping mechanism by a hinge, the locking plug is installed in the No. 2 clamping mechanism, the sleeve is connected to the No. 2 clamping mechanism by welding, and the jacking plate is welded to the No. 2 clamping mechanism; an end plate is installed at one end of the anchor rod body close to the No. 2 clamping mechanism, the end plate and the anchor rod body are threadedly connected, the clamping plug is connected to the mechanism body by a thread, one end of the support guide is welded to the ball valve, and the other end is connected to the mechanism body by embedding, one end of the clamping spring is connected to the support guide, and the other end is connected to the clamping plug, the No. 1 support rod is provided with a protrusion at one end close to the No. 2 support rod, and the sleeve is provided with a groove at one end close to the No. 1 support rod.

[0008] Preferably, the pressing force of the locking buckles in the No. 1 pressing mechanism and the No. 2 pressing mechanism on the bladder is greater than the grouting pressure when the bladder is expanded.

[0009] Preferably, the diameter of the grouting pipe is 3 cm to 5 cm, there are two slurry discharge channels, which are symmetrically distributed along the central axis of the second clamping mechanism, and the diameter of the slurry discharge channel is 1 cm to 3 cm.

[0010] Preferably, the capsule is made of alloy material, the thickness of the capsule is 1 mm to 5 mm, the capsule is folded in multiple layers, and the cross-sectional diameter of the capsule after folding is smaller than the diameter of the No. 2 clamping mechanism.

[0011] Preferably, the sleeve is a hexagonal tubular structure, and the sleeve is divided into two parts, a grooved section and a non-grooved section. The diameter of the sleeve with the grooved section gradually increases from the side of the No. 1 support rod to the side of the No. 2 clamping mechanism, and the diameter of the sleeve without the grooved section gradually increases from the side of the No. 1 support rod to the side of the No. 2 clamping mechanism. The minimum diameters of the sleeve with the grooved section and the sleeve without the grooved section are the same, and the slope of the sleeve with the grooved section is 1:10~1:1.2.

[0012] Preferably, the locking plug is a truncated cone-shaped structure, the side of the truncated cone-shaped structure is provided with engaging teeth, and the inner wall of the engaging cavity in the second clamping mechanism is provided with engaging grooves.

[0013] Preferably, the No. 1 support rod, the No. 2 support rod and the No. 3 support rod are all in groups of six, corresponding to the hexagonal structure of the sleeve, the No. 1 support rod is thicker at the end close to the No. 1 clamping mechanism, and the length of the No. 1 support rod is 30cm~50cm, the No. 2 support rod is a double-row structure, the length of the No. 2 support rod is 20cm~40cm, the length of the No. 3 support rod is 50cm~80cm, and the No. 2 support rod is connected to the position between 1 / 2~2 / 3 of the length of the No. 3 support rod.

[0014] Preferably, the compression spring is always in a compressed state, and the compression condition of the compression spring is adjusted according to the depth of the compression plug entering the mechanism body, and the compression force of the compression spring support guide frame is greater than the resistance overcome by the sliding of the No. 1 compression mechanism.

[0015] A construction method of an end-expanded anchor rod, characterized in that an end-expanded anchor rod is used for construction, and the specific construction steps are as follows:

[0016] Step 1: Preliminary test;

[0017] First, a preliminary test is carried out on the ground. Water is injected into the sliding sleeve through the grouting pipe. The initial water injection pressure is 0.2MPa~0.5MPa, and the water injection pressure is gradually increased to 1.0MPa~2.0MPa, which lasts for 1min~2min. The water injection pressure is increased step by step, by 0.5MPa at each stage, and each stage lasts for 1min~2min. The critical water injection pressure when water just enters the bladder is recorded until the bladder is fully expanded. When the total flow rate of water in the grouting channel reaches 90% of the injected water flow rate, the maximum water injection pressure Q at which the bladder expands is recorded. The compression force of the spring is changed by the compression plug. The above process is repeated, and the position of the compression plug relative to the main body under different critical water injection pressures is recorded.

[0018] Step 2: Drilling construction;

[0019] Use drilling rig to carry out drilling operation according to the design plan;

[0020] Step 3: Lower the anchor rod;

[0021] Determine the geological conditions at the end of the anchor bolt according to the geological survey data, calculate the minimum grouting pressure required for the expansion of the bladder according to the geological conditions, and determine the critical water injection pressure by changing the position of the compression plug relative to the main body according to the pre-test data to ensure that the critical water injection pressure is less than the minimum grouting pressure; connect the pressure-resistant pipe with the grouting pipe, lead the grouting inlet to the surface through the pressure-resistant pipe, connect the grouting outlet of the grouting equipment with the pressure-resistant pipe, then overlap the jacking equipment of the drilling rig with the jacking plate and jack the end-expanded anchor bolt, jack the end-expanded anchor bolt to the designed depth, and then retract the jacking equipment;

[0022] Step 4: bladder grouting;

[0023] When grouting is performed in the sleeve through the grouting pipe, the mud in the borehole and the surrounding soil squeeze the sac and the No. 3 support rod, and the No. 3 support rod presses the No. 2 support rod. As the slurry pushes the No. 1 clamping mechanism to move in the sleeve, the No. 1 clamping mechanism drives the No. 1 support rod to move. The No. 1 support rod is forced to move on the casing by the pressure of the No. 2 support rod. The No. 1 support rod drives the No. 2 support rod to move, and the No. 2 support rod drives the No. 3 support rod to move. The No. 3 support rod supports the sac until the No. 1 clamping mechanism slides to the end of the sleeve. At this time, the slurry pushes the ball valve open, and the slurry flows into the sac from the grouting channel. When the sac is gradually filled with slurry, with the continuous injection of slurry, the grouting pressure is increased to Q~2Q, the volume of the sac expands to the set value, and the No. 1 support rod, the No. 2 support rod, and the No. 3 support rod are all opened to the set position. At the same time, the slurry overflows from the slurry discharge channel. When the slurry overflows from the borehole orifice, the grouting is continued for 1min~2min.

[0024] Step 5: Prestressing

[0025] After the solidified material slurry is finally set and 5-10 days after the grouting is completed, the anchor rod is tensioned by a jack. As the tensioning force increases, the locking plug moves into the No. 2 clamping mechanism, and the bite teeth on the surface of the locking plug bite with the No. 2 clamping mechanism. After the tensioning force reaches the design value, the tension is maintained for 1min~2min;

[0026] Step 6: Construction is completed.

[0027] Beneficial technical effects brought by the present invention:

[0028] The main force is applied to the supporting rods by the slurry pressure, and the bladder is filled with high-pressure slurry, thereby ensuring the reliability of the full deployment of the bladder; by setting up multiple supporting rods, the strength of the anchor body itself is enhanced to ensure that the anchor body itself will not be broken during operation; by using rigid materials for the bladder, the squeezing and expanding effect of the bladder on the surrounding soil is enhanced, thereby improving the mechanical properties of the surrounding soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1The present invention is a schematic diagram of a longitudinal section of the structure of an end-expanded anchor rod and a construction method thereof.

[0030] Figure 2 The present invention is a schematic structural diagram of an end-expanded anchor rod and a No. 1 clamping mechanism in a construction method thereof.

[0031] Figure 3 The present invention is a schematic diagram of a cross-sectional structure of an end-expanded anchor rod and a construction method thereof.

[0032] Figure 4 The present invention is a schematic structural diagram of a sleeve in an end-expanded anchor rod and a construction method thereof.

[0033] Figure 5 The present invention is a schematic structural cross-section diagram of a sleeve in an end-expanded anchor rod and a construction method thereof.

[0034] Figure 6 The present invention is a schematic structural diagram of an end-expanded anchor rod and a No. 1 support rod in a construction method thereof.

[0035] Among them, 1-anchor rod, 2-No. 1 clamping mechanism, 3-bladder, 4-locking plug, 5-No. 1 support rod, 6-No. 2 support rod, 7-No. 3 support rod, 8-grouting pipe, 9-casing, 10-discharge channel, 11-end plate, 12-No. 2 clamping mechanism, 13-sliding sleeve, 14-smooth pipe, 15-jacking plate, 21-mechanism body, 22-locking buckle, 23-sealing rubber ring, 24-ball valve, 25-support guide frame, 26-grouting channel, 27-clamping plug, 28-clamping spring. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0037] Embodiment 1:

[0038] like Figures 1 to 6As shown, an end-expanded anchor rod 1 is characterized in that it includes an anchor rod body 1, a No. 1 clamping mechanism 2, a capsule 3, a locking plug 4, a No. 1 support rod 5, a No. 2 support rod 6, a No. 3 support rod 7, a grouting pipe 8, a casing 9, a grouting channel 10, an end plate 11, a No. 2 clamping mechanism 12, a sliding sleeve 13, a smooth pipe 14, and a jacking plate 15; the No. 1 clamping mechanism 2 includes a mechanism body 21, a locking buckle 22, a sealing rubber ring 23, a ball valve 24, a support guide 25, a grouting channel 26, a clamping plug 27, and a clamping spring 2 8; The outside of the anchor rod 1 is welded with a smooth tube 14, and the smooth tube 14 is connected to the sleeve 13 by welding. The second clamping mechanism 12 includes a mechanism body 21, a locking buckle 22, a grouting channel 10, and a bite cavity. The grouting pipe 8 passes through the sleeve 13 and is welded on the sleeve 13. The first clamping mechanism 2 is installed in the sleeve 13. A sealing rubber ring 23 is installed between the first clamping mechanism 2 and the sleeve 13 and the smooth tube 14. One end of the capsule 3 is connected to the locking buckle 22 of the first clamping structure, and the other end of the capsule 3 is connected to the locking buckle 22 of the first clamping structure. One end is connected to the locking buckle 22 of the No. 2 clamping structure, the No. 1 support rod 5 is connected to the No. 1 clamping mechanism 2 by hinges, the No. 1 support rod 5 is connected to the No. 2 support rod 6 by hinges, the No. 2 support rod 6 is connected to the No. 3 support rod 7 by hinges, the No. 3 support rod 7 is connected to the No. 2 clamping mechanism 12 by hinges, the locking plug 4 is installed in the No. 2 clamping mechanism 12, the sleeve 9 is connected to the No. 2 clamping mechanism 12 by welding, and the jacking plate 15 is welded to the No. 2 clamping mechanism 12; the anchor rod 1 body is An end plate 11 is installed near one end of the No. 2 clamping mechanism 12, and the end plate 11 is connected to the rod body of the anchor rod 1 by a thread. The clamping plug 27 is connected to the mechanism body 21 by a thread. One end of the support guide 25 is welded to the ball valve 24, and the other end is connected to the mechanism body 21 by an embedded connection. One end of the clamping spring 28 is connected to the support guide 25, and the other end is connected to the clamping plug 27. A protrusion is provided at one end of the No. 1 support rod 5 near the No. 2 support rod 6, and a groove is provided at one end of the sleeve 9 near the No. 1 support rod 5.

[0039] Preferably, the pressing force of the locking buckle 22 in the No. 1 pressing mechanism 2 and the No. 2 pressing mechanism 12 on the bladder 3 is greater than the grouting pressure when the bladder 3 is expanded.

[0040] Preferably, the diameter of the grouting pipe 8 is 3 cm to 5 cm, and there are two slurry discharge channels 10, which are symmetrically distributed along the central axis of the second clamping mechanism 12, and the diameter of the slurry discharge channel 10 is 1 cm to 3 cm.

[0041] Preferably, the capsule 3 is made of alloy material, the thickness of the capsule 3 is 1 mm to 5 mm, the capsule 3 is folded in multiple layers, and the cross-sectional diameter of the capsule 3 after folding is smaller than the diameter of the second clamping mechanism 12 .

[0042] Preferably, the sleeve 9 is a hexagonal tubular structure, and the sleeve 9 is divided into two parts, a grooved section and a non-grooved section. The diameter of the grooved section sleeve 9 gradually increases from the side of the No. 1 support rod 5 to the side of the No. 2 clamping mechanism 12, and the diameter of the non-grooved section sleeve 9 gradually increases from the side of the No. 1 support rod 5 to the side of the No. 2 clamping mechanism 12. The minimum diameters of the grooved section and the non-grooved section sleeve 9 are the same, and the slope of the grooved section sleeve 9 is 1:10~1:1.2.

[0043] Preferably, the locking plug 4 is a truncated cone-shaped structure, the side of the truncated cone-shaped structure is provided with engaging teeth, and the inner wall of the engaging cavity in the second clamping mechanism 12 is provided with engaging grooves.

[0044] Preferably, the No. 1 support rod 5, the No. 2 support rod 6, and the No. 3 support rod 7 are all in six groups, corresponding to the hexagonal structure of the sleeve 9. The end of the No. 1 support rod 5 close to the No. 1 clamping mechanism 2 is thicker, and the length of the No. 1 support rod 5 is 30cm~50cm. The No. 2 support rod 6 is a double-row structure, and the length of the No. 2 support rod 6 is 20cm~40cm. The length of the No. 3 support rod 7 is 50cm~80cm, and the No. 2 support rod 6 is connected to the position between 1 / 2~2 / 3 of the length of the No. 3 support rod 7.

[0045] Preferably, the compression spring 28 is always in a compressed state, and the compression condition of the compression spring 28 is adjusted according to the depth of the compression plug 27 entering the mechanism body 21. The compression force of the compression spring 28 supporting the guide frame 25 is greater than the resistance overcome by the sliding of the No. 1 compression mechanism 2.

[0046] Embodiment 2:

[0047] like Figures 1 to 6 As shown, a construction method of an end-expanded anchor rod 1 is characterized in that an end-expanded anchor rod 1 is used for construction, and the specific construction steps are as follows:

[0048] Step 1: Preliminary test;

[0049] First, a preliminary test is carried out on the ground, and water is injected into the sliding sleeve 13 through the grouting pipe 8. The initial water injection pressure is 0.2MPa~0.5MPa, and the water injection pressure is gradually increased to 1.0MPa~2.0MPa, which lasts for 1min~2min. The water injection pressure is increased step by step, and each level is increased by 0.5MPa, and each level lasts for 1min~2min. The critical water injection pressure when water just enters the bladder 3 is recorded until the bladder 3 is fully expanded. When the total flow rate of the water flow in the slurry discharge channel 10 reaches 90% of the injected water flow rate, the maximum water injection pressure Q of the bladder 3 at this time is recorded, and the compression force of the spring is changed by the compression plug 27. The above process is repeated, and the position of the compression plug 27 relative to the main body under different critical water injection pressures is recorded.

[0050] Step 2: Drilling construction;

[0051] Use drilling rig to carry out drilling operation according to the design plan;

[0052] Step 3: lowering anchor rod 1;

[0053] Determine the geological conditions at the end of the anchor rod 1 according to the geological survey data, calculate the minimum grouting pressure required for the expansion of the bladder 3 according to the geological conditions, and determine the critical water injection pressure by changing the position of the compression plug 27 relative to the main body according to the pre-test data to ensure that the critical water injection pressure is less than the minimum grouting pressure; connect the pressure-resistant pipe with the grouting pipe 8, lead the grouting inlet to the surface through the pressure-resistant pipe, connect the grouting outlet of the grouting equipment with the pressure-resistant pipe, then overlap the jacking equipment of the drilling rig with the jacking plate 15 and jack the end-expanded anchor rod 1, jack the end-expanded anchor rod 1 to the designed depth, and then retract the jacking equipment;

[0054] Step 4: grouting of the capsule 3;

[0055] Grout is injected into the sliding sleeve 13 through the grouting pipe 8. At this time, the mud in the borehole and the surrounding soil squeeze the sac 3 and the No. 3 support rod 7. The No. 3 support rod 7 presses the No. 2 support rod 6. As the slurry pushes the No. 1 pressing mechanism 2 to move in the sliding sleeve 13, the No. 1 pressing mechanism 2 drives the No. 1 support rod 5 to move. The No. 1 support rod 5 is subjected to the pressure of the No. 2 support rod 6, forcing the No. 1 support rod 5 to move on the casing 9. The No. 1 support rod 5 drives the No. 2 support rod 6 to move. The No. 2 support rod 6 drives the No. 3 support rod 7 to move. The No. 3 support rod 7 props up The sac 3 is opened until the No. 1 clamping mechanism 2 slides to the end of the sliding sleeve 13. At this time, the slurry pushes the ball valve 24 open, and the slurry flows into the sac 3 from the grouting channel 26. When the sac 3 is gradually filled with the slurry, the grouting pressure is increased to Q~2Q with the continuous injection of the slurry. The volume of the sac 3 is expanded to the set value, and the No. 1 support rod 5, the No. 2 support rod 6, and the No. 3 support rod 7 are all opened to the set position. At the same time, the slurry overflows from the slurry discharge channel 10. When the slurry overflows from the borehole orifice, the grouting is continued for 1min~2min.

[0056] Step 5: Prestressing

[0057] After the solidified material slurry is finally set and 5-10 days after the grouting is completed, the anchor rod 1 is tensioned by a jack. As the tensioning force increases, the locking plug 4 moves into the second clamping mechanism 12, and the bite teeth on the surface of the locking plug 4 are engaged with the second clamping mechanism 12. After the tensioning force reaches the design value, the tension is maintained for 1min~2min;

[0058] Step 6: Construction is completed.

[0059] The present invention relates to an end-expanded anchor rod and a construction method thereof. The main force is applied to the supporting rods by means of slurry pressure, and the bladder is filled with high-pressure slurry, thereby ensuring the reliability of the bladder being fully deployed. By arranging a plurality of supporting rods, the strength of the anchor body itself is enhanced, thereby ensuring that the anchor body itself will not be broken during operation. By using rigid materials for the bladder, the squeezing and expanding effect of the bladder on the surrounding soil is enhanced.

[0060] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention also fall within the protection scope of the present invention.

Claims

1. An end-expanded anchor rod, characterized in that: The invention comprises an anchor rod body, a No. 1 clamping mechanism, a bladder body, a locking plug, a No. 1 support rod, a No. 2 support rod, a No. 3 support rod, a grouting pipe, a casing, a grouting channel, an end plate, a No. 2 clamping mechanism, a sliding sleeve, a smooth pipe and a jacking plate; the No. 1 clamping mechanism comprises a mechanism main body, a locking buckle, a sealing rubber ring, a ball valve, a support guide frame, a grouting channel, a clamping plug and a clamping spring; a smooth pipe is welded to the outside of the anchor rod body, and the smooth pipe is connected to the sliding sleeve by welding. The No. 2 clamping mechanism comprises a mechanism main body, a locking buckle, a grouting channel and a bite cavity. The grouting pipe passes through the sliding sleeve and is welded on the sliding sleeve. The No. 1 clamping mechanism is installed in the sliding sleeve, and sealing rubber rings are installed between the No. 1 clamping mechanism and the sliding sleeve and the smooth pipe. One end of the bladder body is connected to the locking buckle of the No. 1 clamping structure, and the other end of the bladder body is connected to the locking buckle of the No. 2 clamping structure. The rod is connected to the No. 1 clamping mechanism by a hinge, the No. 1 support rod is connected to the No. 2 support rod by a hinge, the No. 2 support rod is connected to the No. 3 support rod by a hinge, the No. 3 support rod is connected to the No. 2 clamping mechanism by a hinge, the locking plug is installed in the No. 2 clamping mechanism, the sleeve is connected to the No. 2 clamping mechanism by welding, and the jacking plate is welded to the No. 2 clamping mechanism; an end plate is installed at one end of the anchor rod body close to the No. 2 clamping mechanism, the end plate and the anchor rod body are threadedly connected, the clamping plug is connected to the mechanism body by a thread, one end of the support guide is welded to the ball valve, and the other end is connected to the mechanism body by embedding, one end of the clamping spring is connected to the support guide, and the other end is connected to the clamping plug, the No. 1 support rod is provided with a protrusion at one end close to the No. 2 support rod, and the sleeve is provided with a groove at one end close to the No. 1 support rod; The pressing force of the locking buckles in the No. 1 pressing mechanism and the No. 2 pressing mechanism on the bladder is greater than the grouting pressure when the bladder expands; The diameter of the grouting pipe is 3 cm to 5 cm, and there are two grouting channels, which are symmetrically distributed along the central axis of the second clamping mechanism, and the diameter of the grouting channel is 1 cm to 3 cm; Grout is injected into the sleeve through the grouting pipe. At this time, the mud in the borehole and the surrounding soil squeeze the bladder and the No. 3 support rod. The No. 3 support rod presses the No. 2 support rod. As the slurry pushes the No. 1 clamping mechanism to move in the sleeve, the No. 1 clamping mechanism drives the No. 1 support rod to move. The No. 1 support rod is subjected to the pressure of the No. 2 support rod, forcing the No. 1 support rod to move on the casing. The No. 1 support rod drives the No. 2 support rod to move, and the No. 2 support rod drives the No. 3 support rod to move. The No. 3 support rod holds up the bladder until the No. 1 clamping mechanism slides to the end of the sleeve. At this time, the slurry pushes open the ball valve, and the slurry flows into the bladder from the grouting channel.

2. The end-expanded anchor rod according to claim 1, characterized in that: The capsule is made of alloy material, has a thickness of 1 mm to 5 mm, is folded in multiple layers, and has a cross-sectional diameter that is smaller than the diameter of the No. 2 clamping mechanism after folding.

3. The end-expanded anchor rod according to claim 1, characterized in that: The sleeve is a hexagonal tubular structure, and is divided into two parts: a grooved section and a non-grooved section. The diameter of the sleeve with the grooved section gradually increases from the side of the No. 1 support rod to the side of the No. 2 clamping mechanism, and the diameter of the sleeve without the grooved section gradually increases from the side of the No. 1 support rod to the side of the No. 2 clamping mechanism. The minimum diameters of the sleeve with the grooved section and the sleeve without the grooved section are the same, and the slope of the sleeve with the grooved section is 1:10~1:1.

2.

4. The end-expanded anchor rod according to claim 1, characterized in that: The locking plug is a truncated cone-shaped structure, the side of the truncated cone-shaped structure is provided with engaging teeth, and the inner wall of the engaging cavity in the second clamping mechanism is provided with an engaging groove.

5. The end-expanded anchor rod according to claim 1, characterized in that: The No. 1 support rod, No. 2 support rod and No. 3 support rod are all in groups of six, corresponding to the hexagonal structure of the sleeve. The end of the No. 1 support rod close to the No. 1 clamping mechanism is thicker, and the length of the No. 1 support rod is 30cm~50cm. The No. 2 support rod is a double-row structure, and the length of the No. 2 support rod is 20cm~40cm. The length of the No. 3 support rod is 50cm~80cm, and the No. 2 support rod is connected to the position between 1 / 2~2 / 3 of the length of the No. 3 support rod.

6. The end-expanded anchor rod according to claim 1, characterized in that: The compression spring is always in a compressed state, and the compression of the compression spring is adjusted according to the depth of the compression plug entering the mechanism body. The compression force of the compression spring support guide frame is greater than the resistance overcome by the sliding of the No. 1 compression mechanism.

7. A construction method of an end-expanded anchor rod, characterized in that: The end-expanded anchor rod according to claim 1 is used for construction, and the specific construction steps are as follows: Step 1: Preliminary test; First, a preliminary test is carried out on the ground. Water is injected into the sliding sleeve through the grouting pipe. The initial water injection pressure is 0.2MPa~0.5MPa, and the water injection pressure is gradually increased to 1.0MPa~2.0MPa, which lasts for 1min~2min. The water injection pressure is increased step by step, by 0.5MPa at each stage, and each stage lasts for 1min~2min. The critical water injection pressure when water just enters the bladder is recorded until the bladder is fully expanded. When the total flow rate of water in the grouting channel reaches 90% of the injected water flow rate, the maximum water injection pressure Q of the bladder expansion at this time is recorded. The compression force of the spring is changed by the compression plug. The above process is repeated, and the position of the compression plug relative to the main body under different critical water injection pressures is recorded. Step 2: Drilling construction; Use drilling rig to carry out drilling operation according to the design plan; Step 3: Lower the anchor rod; Determine the geological conditions at the end of the anchor bolt according to the geological survey data, calculate the minimum grouting pressure required for the expansion of the bladder according to the geological conditions, and determine the critical water injection pressure by changing the position of the compression plug relative to the main body according to the pre-test data to ensure that the critical water injection pressure is less than the minimum grouting pressure; connect the pressure-resistant pipe with the grouting pipe, lead the grouting inlet to the surface through the pressure-resistant pipe, connect the grouting outlet of the grouting equipment with the pressure-resistant pipe, then overlap the jacking equipment of the drilling rig with the jacking plate and jack the end-expanded anchor bolt, jack the end-expanded anchor bolt to the designed depth, and then retract the jacking equipment; Step 4: bladder grouting; When grouting is performed in the sleeve through the grouting pipe, the mud in the borehole and the surrounding soil squeeze the sac and the No. 3 support rod, and the No. 3 support rod presses the No. 2 support rod. As the slurry pushes the No. 1 clamping mechanism to move in the sleeve, the No. 1 clamping mechanism drives the No. 1 support rod to move. The No. 1 support rod is forced to move on the casing by the pressure of the No. 2 support rod. The No. 1 support rod drives the No. 2 support rod to move, and the No. 2 support rod drives the No. 3 support rod to move. The No. 3 support rod supports the sac until the No. 1 clamping mechanism slides to the end of the sleeve. At this time, the slurry pushes the ball valve open, and the slurry flows into the sac from the grouting channel. When the sac is gradually filled with slurry, with the continuous injection of slurry, the grouting pressure is increased to Q~2Q, the volume of the sac expands to the set value, and the No. 1 support rod, the No. 2 support rod, and the No. 3 support rod are all opened to the set position. At the same time, the slurry overflows from the slurry discharge channel. When the slurry overflows from the borehole orifice, the grouting is continued for 1min~2min. Step 5: Prestressing After the solidified material slurry is finally set and 5-10 days after the grouting is completed, the anchor rod is tensioned by a jack. As the tensioning force increases, the locking plug moves into the No. 2 clamping mechanism, and the bite teeth on the surface of the locking plug bite with the No. 2 clamping mechanism. After the tensioning force reaches the design value, the tension is maintained for 1min~2min; Step 6: Construction is completed.

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