A repeatable multi-stage blasting grouting anchor rod and a multi-time blasting grouting method

Abstract

The application discloses a kind of repeatable multistage blasting grouting anchor rod and multiple blasting grouting method, belong to grouting anchor rod technical field.A kind of repeatable multistage blasting grouting anchor rod, including inner layer grouting anchor rod and outer layer grouting anchor rod;Inner layer grouting anchor rod is the hollow structure of outer end opening, and the outer end circumference side wall of inner layer grouting anchor rod is sleeved with sealing pad, and the circumference side wall of inner layer grouting anchor rod is provided with first overflow hole, and inner layer grouting anchor rod is provided with bursting disc, and bursting disc closes first overflow hole;Outer layer grouting anchor rod is the hollow structure of outer end opening, inner end closed, and the outer end circumference side wall of outer layer grouting anchor rod is sleeved with stop plug, and the circumference side wall of outer layer grouting anchor rod is provided with second overflow hole corresponding to first overflow hole, and the inner end of outer layer grouting anchor rod is provided with anchor head.The inner layer grouting anchor rod in the application plays the role of placing and fixing bursting disc, can be taken out at the end of grouting and reinstalled different pressure bursting disc to carry out grading grouting under different pressure.

Description

Technical Field

[0001] This invention belongs to the field of grouting anchor technology, specifically relating to a repeatable multi-stage blasting grouting anchor and a method for multiple blasting grouting. Background Technology

[0002] When encountering fault fracture zones, pressure water threats to the coal seam floor, or significant deformation of the surrounding rock during tunnel excavation, grouting support is often employed. Grouting support can improve the integrity, stability, and impermeability of the surrounding rock, control its deformation and displacement, and fully utilize its own supporting function. The grouting process typically varies depending on the specific support problem. When the purpose of grouting is to reduce the permeability of the floor or surrounding rock, a higher grouting pressure is required to ensure the grout is injected as densely as possible, while the pull-out force provided by the anchor bolts themselves has a relatively smaller effect.

[0003] In grouting processes primarily aimed at controlling deformation in soft rock tunnels, a certain pressure is required to expand the grout seepage area, reinforcing the weak surrounding rock into a unified structure and thus reducing deformation. Therefore, it is necessary to increase the seepage range of the grout in low-strength and low-permeability soft rock. The optimal grouting conditions involve higher pressure at the deeper part of the anchor bolt and lower pressure at the shallower part, preventing rapid grout leakage caused by surface damage. Furthermore, sometimes multiple grouting reinforcements are required in areas that have already been grouted.

[0004] In traditional grouting anchors, the grout pressure decreases from shallow to deep, making grout leakage prone to occur at the tunnel surface. This results in the deep grout pressure failing to meet design requirements, affecting the grouting effect. In scenarios requiring multiple grouting operations, traditional grouting anchors are highly susceptible to clogging, impacting subsequent grouting results. Furthermore, traditional anchors are mostly disposable, leading to waste in situations where the pull-out force provided by the anchor itself is not crucial. Summary of the Invention

[0005] The purpose of this invention is to provide a repeatable multi-stage blasting grouting anchor and a method for multiple blasting grouting, so as to realize graded grouting or multiple grouting under different pressures through the grouting anchor.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A repeatable multi-stage blasting grouting anchor bolt includes an inner grouting anchor bolt and an outer grouting anchor bolt;

[0008] The inner grouting anchor is a hollow structure with an open outer end. A sealing gasket is fitted on the outer circumferential side wall of the inner grouting anchor. A first overflow hole is provided on the circumferential side wall of the inner grouting anchor. A rupture disc is provided on the inner grouting anchor, and the rupture disc seals the first overflow hole.

[0009] The outer grouting anchor rod is a hollow structure with an open outer end and a closed inner end. A grout stop plug is fitted on the outer circumferential side wall of the outer grouting anchor rod. A second grout overflow hole corresponding to the first grout overflow hole is provided on the circumferential side wall of the outer grouting anchor rod. An anchor head is provided on the inner end of the outer grouting anchor rod.

[0010] When the inner grouting anchor is installed inside the outer grouting anchor, the second overflow hole is aligned with the first overflow hole.

[0011] Preferably, the inner grouting anchor has a plurality of first overflow holes arranged along the axial and / or circumferential direction on its circumferential sidewall, and the blasting pressure of the blasting discs on the plurality of first overflow holes is different.

[0012] Preferably, from the outer end to the inner end of the inner grouting anchor, the bursting pressure of the rupture discs on each first overflow hole increases sequentially.

[0013] Preferably, the inner grouting anchor has a plurality of first overflow holes arranged along the axial and / or circumferential direction on its circumferential sidewall, and the blasting pressure of the blasting discs on the plurality of first overflow holes is the same.

[0014] Preferably, the first overflow hole has a stepped hole structure, which includes an annular groove portion with a rupture disc and a through hole portion for the flow of slurry.

[0015] Preferably, a first threaded connection is provided on the inner side of the inner end of the outer grouting anchor rod, and a second threaded connection is provided on the outer side of the inner end of the inner grouting anchor rod. The first threaded connection and the second threaded connection are fixedly connected by threads.

[0016] Preferably, the outer end of the outer grouting anchor is provided with an outer rod nut and a washer. The outer rod nut and the washer are both located on the side of the grout stop plug near the outer end of the outer grouting anchor. The outer rod nut and the outer grouting anchor are connected by threads. The washer is pressed against the grout stop plug by screwing the outer rod nut and the outer grouting anchor together.

[0017] Preferably, the outer end of the inner grouting anchor is provided with an inner rod nut. The inner rod nut is located on the side of the sealing gasket near the outer end of the inner grouting anchor. The inner rod nut and the inner grouting anchor are connected by threads. The inner rod nut is screwed into the inner grouting anchor to press the sealing gasket.

[0018] Preferably, the outer grouting anchor includes a left half outer grouting anchor and a right half outer grouting anchor. The rod body of the left half outer grouting anchor is provided with a first protrusion and a first groove, and the rod body of the right half outer grouting anchor is provided with a second groove corresponding to the first protrusion and a second protrusion corresponding to the first groove.

[0019] The connection is achieved by the first protrusion engaging the second groove, and the second protrusion engaging the first groove.

[0020] A multiple-stage blasting grouting method, applied to the aforementioned repeatable multi-stage blasting grouting anchor bolt, includes the following steps:

[0021] Step 1: Fix the outer grouting anchor rod in the borehole with anchoring agent. According to the actual working conditions, place several rupture discs in different first overflow holes. Screw the first threaded connection and the second threaded connection to align the second overflow hole with the first overflow hole.

[0022] Step 2: Connect the grouting pump to the outer end of the inner grouting anchor and turn on the grouting pump. Adjust the grouting pressure from low to high to make the rupture discs with different rupture pressures rupture in sequence, and perform graded grouting at different pressures.

[0023] Step 3: When the grout can no longer be injected or the set maximum grouting pressure is reached, turn off the grouting pump and stop the first grouting.

[0024] Step 4: If multiple stages of grouting are required according to actual working conditions, disassemble the inner grouting anchor rod and replace it with a new rupture disc with a different rupture pressure. Reinstall the inner grouting anchor rod on the outer grouting anchor rod and connect the grouting pump to the inner grouting anchor rod for staged grouting.

[0025] If multiple grouting is not required, remove the inner grouting anchor rod, connect the grouting pump outlet to the outer grouting anchor rod, and turn on the grouting pump to perform secondary grouting;

[0026] Step 5: Once the maximum pressure set for secondary grouting or staged grouting is reached, turn off the grouting pump and stop grouting.

[0027] Step Six: Based on the actual working conditions, different treatments are applied to the outer grouting anchor bolts and the inner grouting anchor bolts;

[0028] When the grout viscosity is low and the pull-out force is not required to provide pull-out force by repeatable multi-stage blasting grouting anchors, both the outer and inner grouting anchors are removed.

[0029] In the case where repeatable multi-stage blasting grouting anchor bolts need to provide low pull-out force, the inner grouting anchor bolt is removed and the outer grouting anchor bolt is left in the borehole;

[0030] In applications where repeatable multi-stage blasting grouting anchors require a large pull-out force, both the outer and inner grouting anchors are left inside the borehole.

[0031] The beneficial technical effects of this invention are:

[0032] The repeatable multi-stage grouting anchor bolt of this invention differs from traditional grouting anchor bolts. The grouting anchor bolt of this invention includes an inner grouting anchor bolt and an outer grouting anchor bolt. The inner grouting anchor bolt serves to place and fix the rupture discs. The inner grouting anchor bolt can be removed at the end of grouting, or the outer grouting anchor bolt can be used directly for secondary grouting. Subsequently, the inner grouting anchor bolt can be reinstalled for multiple stages of grouting according to actual working conditions.

[0033] The outer grouting anchor bolt adopts a detachable connection, which is convenient for assembly and disassembly, so that the outer grouting anchor bolt can be reused multiple times.

[0034] This invention provides, on the one hand, a rupture disc that can penetrate under rated burst pressure in the overflow hole of a traditional grouting anchor, so that the injected grout has a certain impact pressure, and on the other hand, it can achieve graded grouting at different pressures by subsequently replacing the rupture disc with a different burst pressure.

[0035] The inner grouting anchor has several first overflow holes along the axial and / or circumferential directions on its circumferential sidewall. The bursting pressure of the bursting discs on the several first overflow holes is different. From the outer end to the inner end of the inner grouting anchor, the bursting pressure of the bursting discs on each first overflow hole increases sequentially.

[0036] When this repeatable multi-stage blasting grouting anchor is grouted, the lower-pressure blasting disc at the outer end of the inner grouting anchor detonates first, injecting grout at a lower pressure into the shallow part of the rock stratum and gradually sealing off the shallow area. When the shallow part of the rock stratum is filled, the higher-pressure blasting disc at the inner end of the inner grouting anchor detonates, injecting grout at a higher pressure into the deeper part of the rock stratum, thus achieving staged grouting at different pressures. Specifically, when grouting the deeper parts of the rock stratum, the shallow part sealed by the grouting can prevent the grouting in the deeper areas from flowing out of the rock stratum, allowing the grouting to flow into the interior of the rock stratum, thereby increasing the grouting range of the repeatable multi-stage blasting grouting anchor within the rock stratum.

[0037] Meanwhile, several blasting discs with the same blasting pressure are set along the axial and / or circumferential direction on the circumferential sidewall of the inner grouting anchor rod. They blast simultaneously under the same grouting pressure, thereby rapidly injecting grout with the same grouting pressure into the rock strata.

[0038] After grouting is completed, the outer and inner grouting anchors can be treated differently depending on the actual working conditions. In cases where the grout viscosity is low and repeated multi-stage blasting grouting anchors are not required to provide pull-out force, both the outer and inner grouting anchors can be removed and reused.

[0039] In situations where repeated multi-stage blasting grouting anchors with low pull-out force are required, the inner grouting anchor is removed, while the outer grouting anchor remains in the borehole. The outer grouting anchor provides a certain pull-out force, and its hollow structure allows space for short-term deformation of the surrounding rock.

[0040] In applications where repeatable multi-stage blasting grouting anchors require significant pull-out force, neither the outer nor inner grouting anchors need to be removed after grouting; they can remain in the borehole, thereby enhancing the tensile and shear strength of the repeatable multi-stage blasting grouting anchors. Attached Figure Description

[0041] Figure 1 This is a front view of a repeatable multi-stage blasting grouting anchor bolt in this embodiment;

[0042] Figure 2 yes Figure 1 A cross-sectional view along the AA direction;

[0043] Figure 3 yes Figure 2 A magnified view of a section at point B in the middle;

[0044] 1-Inner grouting anchor rod, 2-Outer grouting anchor rod, 3-First overflow hole, 4-Second overflow hole, 5-Breaking disc, 6-Inner rod nut, 7-Outer rod nut, 8-Washer, 9-Grouting plug, 10-Anchor head, 11-Sealing gasket, 12-First threaded connection, 13-Second threaded connection, 14-Third threaded connection, 15-Fourth threaded connection, 16-Fifth threaded connection, 17-Sixth threaded connection, 18-First protrusion, 19-First groove, 20-Second protrusion, 21-Second groove, 22-Annular groove, 23-Through hole;

[0045] 201 - Left half outer layer grouting anchor bolt, 202 - Half outer layer grouting anchor bolt;

[0046] 301 - First overflow hole of the first group; 302 - First overflow hole of the second group; 303 - First overflow hole of the third group;

[0047] 401 - Second overflow hole of the first group, 402 - Second overflow hole of the second group, 403 - Second overflow hole of the third group. Detailed Implementation

[0048] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. Certain embodiments of the invention will be described more fully below with reference to the accompanying drawings, and some, but not all, of these embodiments will be shown. In fact, various embodiments of the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to enable the invention to meet applicable legal requirements.

[0049] In the description of this invention, it should be noted that the terms "inner," "outer," "upper," "lower," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In this embodiment of the invention, a repeatable multi-stage blasting grouting anchor bolt and a method for multiple blasting grouting are provided. Please refer to [reference needed]. Figures 1 to 3 As shown.

[0051] A repeatable multi-stage blasting grouting anchor bolt includes an inner grouting anchor bolt 1 and an outer grouting anchor bolt 2.

[0052] The inner grouting anchor 1 is a hollow structure with an open outer end (in this embodiment, the inner grouting anchor 1 with open ends is taken as an example). The outer end of the inner grouting anchor 1 (the end used by the grouting pump for grouting) is fitted with a sealing gasket 11 on its circumferential side wall. The circumferential side wall of the inner grouting anchor 1 is provided with a first overflow hole 3. The first overflow hole 3 is connected to the interior of the inner grouting anchor 1, and the grout can flow out from the interior of the inner grouting anchor 1 through the first overflow hole 3. A rupture disc 5 is provided on the inner grouting anchor 1, and the rupture disc 5 seals the first overflow hole 3.

[0053] The outer grouting anchor 2 is a hollow structure with an open outer end (the end used by the grouting pump for grouting) and a closed inner end (the end placed in the borehole). A grout stop plug 9 is sleeved on the outer circumferential side wall of the outer grouting anchor 2. A second grout overflow hole 4 corresponding to the first overflow hole 3 is provided on the circumferential side wall of the outer grouting anchor 2. The second overflow hole 4 is connected to the interior of the outer grouting anchor 2. When the rupture disc 5 explodes, the grout can flow out from the interior of the outer grouting anchor 2 through the second overflow hole 4. An anchor head 10 is provided at the inner end of the outer grouting anchor 2.

[0054] When the inner grouting anchor 1 is installed inside the outer grouting anchor 2, the second overflow hole 4 is aligned with the first overflow hole 3.

[0055] Furthermore, the inner grouting anchor 1 has several first overflow holes 3 arranged along the axial and / or circumferential directions on its circumferential sidewall, and the bursting pressure of the bursting discs 5 on the several first overflow holes 3 is different.

[0056] Furthermore, from the outer end to the inner end of the inner grouting anchor rod 1, the bursting pressure of the bursting discs 5 on each first overflow hole 3 increases sequentially.

[0057] Furthermore, the inner grouting anchor 1 has several first overflow holes 3 arranged along the axial and / or circumferential directions on its circumferential sidewall, and the bursting pressure of the bursting discs on the several first overflow holes 3 is the same.

[0058] Specifically, the operator can set several first overflow holes 3 at different positions on the circumferential sidewall of the inner grouting anchor 1 (the sidewall of the inner grouting anchor 1 along the axial direction and / or the sidewall of the inner grouting anchor 1 along the circumferential direction) according to the actual working conditions. Several rupture discs 5 with different blasting pressures are set to seal the first overflow holes 3 according to the actual working conditions. Grout with different pressures is injected by the grouting pump, so that the rupture discs 5 with different blasting pressures rupture in sequence, thereby realizing graded grouting at different pressures. When the repeatable multi-stage blasting grouting anchor is grouted, the blasting disc 5 at the outer end of the inner grouting anchor 1 with a lower blasting pressure detonates first. The grout with the lower blasting pressure grouts the shallow part of the rock stratum and gradually seals the shallow area of ​​the rock stratum. When the shallow part of the rock stratum is filled, the blasting disc 5 at the inner end of the inner grouting anchor 1 with a higher blasting pressure detonates. The grout with the higher blasting pressure grouts the deep part of the rock stratum, thus achieving staged grouting at different pressures. In particular, when grouting the deep part of the rock stratum, the shallow part of the rock stratum sealed by the grouting grout can prevent the grouting grout in the deep area from flowing out of the rock stratum, allowing the grouting grout to flow into the interior of the rock stratum, thereby increasing the grouting range of the repeatable multi-stage blasting grouting anchor within the rock stratum.

[0059] In this embodiment, the following technical solution is used as an example: the inner grouting anchor 1 is provided with four first overflow holes 3 on the same cross section. The four first overflow holes 3 are spaced apart along the circumferential sidewall of the inner grouting anchor 1. The four first overflow holes 3 are sealed by rupture discs 5 with the same blasting pressure. The four first overflow holes 3 are defined as a group of first overflow holes. By setting a group of first overflow holes, the rapid grouting of the repeatable multi-stage blasting grouting anchor can be achieved.

[0060] Furthermore, several sets of first overflow holes are arranged sequentially from the outer end to the inner end of the inner grouting anchor 1. In this embodiment, three sets are used as an example, which are defined as the first set of first overflow holes 301, the second set of first overflow holes 302 and the third set of first overflow holes 303 respectively; the blasting pressure of the first set of first overflow holes 301, the second set of first overflow holes 302 and the third set of first overflow holes 303 increases sequentially.

[0061] Correspondingly, the outer grouting anchor 2 has several second overflow holes 4 corresponding to the first overflow holes 3 along its axial or circumferential sidewall. When the inner grouting anchor 1 is located inside the outer grouting anchor 2, the second overflow holes 4 are aligned with the first overflow holes 3. In this embodiment, the outer grouting anchor 2 is provided with a first group of second overflow holes 401 corresponding to the first group of first overflow holes 301, a second group of second overflow holes 402 corresponding to the second group of first overflow holes 302, and a third group of second overflow holes 403 corresponding to the third group of first overflow holes 303.

[0062] In this embodiment, such as Figure 3 As shown, the first overflow hole 3 has a stepped hole structure, which is divided into an annular groove portion 22 for setting the rupture disc 5 (the diameter of the rupture disc 5 is larger than the diameter of the through hole portion 23) and a through hole portion 23 for the flow of grout. The rupture disc 5 is placed between the inner grouting anchor rod 1 and the outer grouting anchor rod 2, and the outer grouting anchor rod 2 and the inner grouting anchor rod 1 further fix the rupture disc 5 by clamping it. The rupture disc 5 can also be glued to the inside of the inner grouting anchor rod 1 to fix the rupture disc 5 and seal the first overflow hole 3.

[0063] In this embodiment, a first threaded connection part 12 is provided on the inner side of the inner end of the outer grouting anchor rod 2, and a second threaded connection part 13 is provided on the outer side of the inner end of the inner grouting anchor rod 1. The outer grouting anchor rod 2 and the inner grouting anchor rod 1 are fixedly connected by the first threaded connection part 12 and the second threaded connection part 13. By adopting a threaded connection method, a detachable connection between the outer grouting anchor rod 2 and the inner grouting anchor rod 1 can be achieved. When the first threaded connection part 12 and the second threaded connection part 13 are tightened, the second overflow hole 4 of the outer grouting anchor rod 2 and the first overflow hole 3 of the inner grouting anchor rod 1 can be aligned (i.e., the first group of first overflow holes 301 aligns with the first group of second overflow holes 401, the second group of first overflow holes 302 aligns with the second group of second overflow holes 402, and the third group of first overflow holes 303 aligns with the third group of second overflow holes 403), which plays a positioning role.

[0064] In this embodiment, a third threaded connection 14 is provided on the outer side of the inner end of the outer grouting anchor rod 2, and a fourth threaded connection 15 is provided on the anchor head 10. The outer grouting anchor rod 2 and the anchor head 10 are fixedly connected by the third threaded connection 14 and the fourth threaded connection 15. The threaded connection facilitates the assembly and disassembly of the anchor head 10 and the outer grouting anchor rod 2. The anchor head 10 adopts a conical structure, which facilitates insertion into the borehole. Compared with traditional anchor heads, the conical anchor head 10 has a larger contact area with the anchoring agent, which enables the outer grouting anchor rod 2 to be more stably fixed inside the borehole.

[0065] In this embodiment, a fifth threaded connection 16 is provided on the outer side of the outer end of the outer grouting anchor rod 2, and a sixth threaded connection 17 is provided on the grout stop plug 9. Specifically, the outer grouting anchor rod 2 and the grout stop plug 9 are fixedly connected by the fifth threaded connection 16 and the sixth threaded connection 17. The grout stop plug 9 is tightly fitted to the borehole wall to prevent grout from flowing back out of the borehole during grouting.

[0066] Furthermore, an outer rod nut 7 and a washer 8 are provided on the circumferential sidewall of the outer end of the outer grouting anchor rod 2. Both the outer rod nut 7 and the washer 8 are located on one side of the grouting plug (the side closest to the outer end of the outer grouting anchor rod 2). The washer 8 is fixedly connected to the grout stop plug 9 by welding. The outer rod nut 7 is connected to the outer grouting anchor rod 2 by thread. By screwing the outer rod nut 7 to the outer grouting anchor rod 2, the washer 8 is pressed against the grout stop plug 9, which can further improve the sealing effect of the grout stop plug 9.

[0067] A sealing gasket 11 is fitted on the circumferential side wall of the outer end of the inner grouting anchor rod 1. The sealing gasket 11 can prevent grout from leaking out through the tiny gap between the outer grouting anchor rod 2 and the inner grouting anchor rod 1.

[0068] Furthermore, an inner rod nut 6 is provided on the circumferential side wall of the outer end of the inner grouting anchor rod 1. The inner rod nut 6 is located on the side of the sealing gasket 11 near the outer end. The inner rod nut 6 and the inner grouting anchor rod 1 are connected by threads. By screwing the inner rod nut 6 and the inner grouting anchor rod 1 together, the sealing gasket 11 can be further tightened, thereby improving the sealing effect of the sealing gasket 11.

[0069] In this embodiment, the outer grouting anchor 2 can be disassembled into two parts: the left half of the outer grouting anchor 201 and the right half of the outer grouting anchor 202. Specifically, a first protrusion 18 is provided on one side of the longitudinal section of the left half of the outer grouting anchor 201, and a first groove 19 is provided on the other side of the longitudinal section of the left half of the outer grouting anchor 201. The heights of the first protrusion 18 and the first groove 19 are the same as the height of the outer grouting anchor 2.

[0070] One side of the longitudinal section of the right half of the outer grouting anchor rod 202 is provided with a second groove 21 corresponding to the first protrusion 18, and the other side of the longitudinal section of the right half of the outer grouting anchor rod 202 is provided with a second protrusion 20 corresponding to the first groove 19. The height of the second protrusion 20 and the second groove 21 is the same as the height of the outer grouting anchor rod 2.

[0071] The left half of the outer layer grouting anchor rod 201 and the right half of the outer layer grouting anchor rod 202 are connected by the first protrusion 18 clamping the second groove 21 and the second protrusion 20 clamping the first groove 19.

[0072] A multiple-stage blasting grouting method, applied to the aforementioned repeatable multi-stage blasting grouting anchor bolt, includes the following steps:

[0073] Step 1: Fix the outer grouting anchor 2 in the borehole with anchoring agent. According to the actual working conditions, place the rupture disc 5 in different first overflow holes 3, and screw the first threaded connection part 12 and the second threaded connection part 13 to align the second overflow hole 4 with the first overflow hole 3.

[0074] Step 2: Connect the grouting pump to the outer end of the inner grouting anchor 1 and turn on the grouting pump. Adjust the grouting pressure from low to high so that the rupture discs 5 with different rupture pressures rupture in sequence, and at the same time perform graded grouting at different pressures.

[0075] Step 3: When the grout can no longer be injected or the set maximum grouting pressure is reached, turn off the grouting pump and stop the first grouting.

[0076] Step 4: If multiple stages of grouting are required according to actual working conditions, disassemble the inner grouting anchor 1 and replace it with a new rupture disc 5 with a different rupture pressure. Reinstall the inner grouting anchor 1 on the outer grouting anchor 2 and connect the grouting pump to the inner grouting anchor 1 for staged grouting.

[0077] If multiple grouting is not required, remove the inner grouting anchor 1, connect the grouting pump outlet to the outer grouting anchor 2, and turn on the grouting pump for secondary grouting;

[0078] Step 5: Once the maximum pressure set for secondary grouting or staged grouting is reached, turn off the grouting pump and stop grouting.

[0079] Step 6: Based on the actual working conditions, different treatments are applied to the outer grouting anchor 2 and the inner grouting anchor 1;

[0080] When the grout viscosity is low and the pull-out force is not required to provide pull-out force by repeatable multi-stage blasting grouting anchors, both the outer grouting anchor 2 and the inner grouting anchor 1 are removed and reused.

[0081] In the case where repeatable multi-stage blasting grouting anchors need to provide low pull-out force, the inner grouting anchor 1 is removed and the outer grouting anchor 2 is left in the borehole. The outer grouting anchor 2 can not only provide a certain pull-out force, but its hollow structure can also provide space for short-term deformation of the surrounding rock.

[0082] In applications where repeatable multi-stage blasting grouting anchors require a large pull-out force, both the outer grouting anchor 2 and the inner grouting anchor 1 are left inside the borehole to enhance the tensile and shear strength of the repeatable multi-stage blasting grouting anchors.

[0083] The present embodiment has now been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the present invention's repeatable multi-stage blasting grouting anchor bolt and multiple blasting grouting method.

[0084] Of course, the specific embodiments described above further illustrate the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for multiple blasting grouting, characterized in that, A repeatable multi-stage blasting grouting anchor bolt is applied, comprising an inner grouting anchor bolt and an outer grouting anchor bolt. The inner grouting anchor bolt is a hollow structure with an open outer end. A sealing gasket is fitted on the outer circumferential sidewall of the inner grouting anchor bolt, and a first overflow hole is provided on the circumferential sidewall of the inner grouting anchor bolt. A blasting disc is provided on the inner grouting anchor bolt, and the blasting disc seals the first overflow hole. The outer grouting anchor bolt is a hollow structure with an open outer end and a closed inner end. A grout-stopping plug is fitted on the outer circumferential sidewall of the outer grouting anchor bolt. The circumferential sidewall of the rod is provided with a second overflow hole corresponding to the first overflow hole, and the inner end of the outer grouting anchor rod is provided with an anchor head; when the inner grouting anchor rod is set inside the outer grouting anchor rod, the second overflow hole is aligned with the first overflow hole; the circumferential sidewall of the inner grouting anchor rod is provided with a plurality of first overflow holes along the axial and / or circumferential directions; the inner side of the inner end of the outer grouting anchor rod is provided with a first threaded connection part, and the outer side of the inner end of the inner grouting anchor rod is provided with a second threaded connection part, and the first threaded connection part and the second threaded connection part are fixedly connected by threads; The method includes the following steps: Step 1: Fix the outer grouting anchor rod in the borehole with anchoring agent. According to the actual working conditions, place several rupture discs in different first overflow holes. Screw the first threaded connection and the second threaded connection to align the second overflow hole with the first overflow hole. Step 2: Connect the grouting pump to the outer end of the inner grouting anchor and turn on the grouting pump. Adjust the grouting pressure from low to high to make the rupture discs with different rupture pressures rupture in sequence, and perform graded grouting at different pressures. Step 3: When the grout can no longer be injected or the set maximum grouting pressure is reached, turn off the grouting pump and stop the first grouting. Step 4: If multiple stages of grouting are required according to actual working conditions, disassemble the inner grouting anchor rod and replace it with a new rupture disc with a different rupture pressure. Reinstall the inner grouting anchor rod on the outer grouting anchor rod and connect the grouting pump to the inner grouting anchor rod for staged grouting. If multiple grouting is not required, remove the inner grouting anchor rod, connect the grouting pump outlet to the outer grouting anchor rod, and turn on the grouting pump to perform secondary grouting; Step 5: Once the maximum pressure set for secondary grouting or staged grouting is reached, turn off the grouting pump and stop grouting. Step Six: Based on the actual working conditions, different treatments are applied to the outer grouting anchor bolts and the inner grouting anchor bolts; When the grout viscosity is low and the pull-out force is not required to provide pull-out force by repeatable multi-stage blasting grouting anchors, both the outer and inner grouting anchors are removed. In the case where repeatable multi-stage blasting grouting anchor bolts need to provide low pull-out force, the inner grouting anchor bolt is removed and the outer grouting anchor bolt is left in the borehole; In applications where repeatable multi-stage blasting grouting anchors require a large pull-out force, both the outer and inner grouting anchors are left inside the borehole.

2. The method for multiple blasting grouting according to claim 1, characterized in that, The rupture pressure of the rupture discs on the several first overflow holes is different.

3. The method for multiple blasting grouting according to claim 2, characterized in that, From the outer end to the inner end of the inner grouting anchor, the bursting pressure of the rupture discs on each first overflow hole increases sequentially.

4. The method for multiple blasting grouting according to claim 1, characterized in that, The inner grouting anchor has a plurality of first overflow holes arranged along the axial and / or circumferential direction on its circumferential sidewall, and the blasting pressure of the blasting discs on the plurality of first overflow holes is the same.

5. The method for multiple blasting grouting according to claim 1, characterized in that, The first overflow hole has a stepped hole structure, which includes an annular groove portion with a rupture disc and a through hole portion for the flow of slurry.

6. The method for multiple blasting grouting according to claim 1, characterized in that, The outer end of the outer grouting anchor is provided with an outer rod nut and a washer. The outer rod nut and the washer are both located on the side of the grout stop plug near the outer end of the outer grouting anchor. The outer rod nut and the outer grouting anchor are connected by threads. The washer is pressed against the grout stop plug by screwing the outer rod nut and the outer grouting anchor together.

7. The method for multiple blasting grouting according to claim 1, characterized in that, The outer end of the inner grouting anchor is provided with an inner rod nut. The inner rod nut is located on the side of the sealing gasket close to the outer end of the inner grouting anchor. The inner rod nut and the inner grouting anchor are connected by threads. The inner rod nut is screwed into the inner grouting anchor to press the sealing gasket.

8. The method for multiple blasting grouting according to claim 1, characterized in that, The outer grouting anchor includes a left half outer grouting anchor and a right half outer grouting anchor. The rod body of the left half outer grouting anchor is provided with a first protrusion and a first groove. The rod body of the right half outer grouting anchor is provided with a second groove corresponding to the first protrusion and a second protrusion corresponding to the first groove. The connection is achieved by the first protrusion engaging the second groove, and the second protrusion engaging the first groove.

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