Multistage pressure-relief anchor rod suitable for rock burst prevention and control in deep mine

Abstract

A kind of multistage yielding anchor rod suitable for deep mine rock burst prevention and control belongs to the technical field of mine safety support, including rod body, tray, nut, wave-shaped yielding sleeve, yielding section and anchoring body;Rod body front end is fixed with borehole bottom through anchoring body;Rod body tail end is fixed with borehole orifice through tray and nut in turn;Wave-shaped yielding sleeve is located in borehole and coaxially sleeved outside rod body, wave-shaped yielding sleeve front end is fixed with borehole bottom through anchoring body, and wave-shaped yielding sleeve tail end is free end;Yielding section is fixed on rod body and used with wave-shaped yielding sleeve to yield and energy-absorbing cooperation.The present application realizes multistage progressive yielding and graded energy dissipation of rod body under axial tension state through phase blocking and releasing of wave-shaped yielding sleeve to yielding section, significantly improves the impact resistance of support system, and realizes the controllable design of anchor rod yielding performance by adjusting the structure parameters of wave-shaped yielding sleeve and yielding section.

Description

Technical Field

[0001] This invention belongs to the field of mine safety support technology, and in particular relates to a multi-stage pressure relief anchor bolt suitable for rockburst prevention and control in deep mines. Background Technology

[0002] As mineral resource mining extends deeper, underground rock masses are generally in a complex mechanical environment of high ground stress and strong excavation disturbance. Rockburst, as the most typical dynamic disaster in deep mines, is essentially the instantaneous and violent release of high elastic strain energy accumulated in the rock mass. It has significant characteristics such as large energy release, strong suddenness, high destructive intensity, and short duration, posing a serious threat to the safety of underground workers, the stability of roadway structures, and the safety of mining equipment.

[0003] Conventional supports are ill-suited to withstand the powerful dynamic impact of rockbursts and are prone to failure under instantaneous loads. Therefore, developing multi-stage relief anchors that combine high load-bearing capacity with multi-stage energy dissipation characteristics has become a critical technical challenge in the field of deep rockburst disaster prevention and control.

[0004] Currently, the anchor bolt support widely used in actual engineering is mainly divided into two categories: rigid anchor bolts and pressure-yielding anchor bolts.

[0005] Traditional rigid rock bolts rely on high-strength bolts and anchoring systems to constrain the surrounding rock. They are characterized by high initial stiffness and strong deformation control, and have been successfully applied in conventional deep rock mass conditions. However, under conditions of high ground stress and rockbursts caused by strong disturbances, the surrounding rock undergoes severe instantaneous deformation, and the rock bolt system is prone to brittle fracture or overall failure, making it difficult to fully meet the support requirements under deep dynamic disaster conditions.

[0006] Therefore, in order to improve the environmental adaptability of the support system, the industry has successively developed a wide variety of pressure relief anchors in recent years, such as pressure relief anchor products based on friction slip and sleeve deformation. These pressure relief anchors, by setting deformable or slippery components on the rod body, allow the anchor to displace after the load reaches the threshold, thereby releasing some of the surrounding rock energy, effectively reducing the risk of structural damage, and promoting the further application of anchor support technology in complex rock conditions.

[0007] However, rockbursts induced by the coupling effect of high stress and blasting disturbance in deep engineering exhibit a significant chain effect, typically occurring multiple times or lasting for a certain period. Conventional support methods are difficult to apply to this type of rockburst. If the initial stiffness of the anchor bolts is too high, they are prone to overload fracture in the initial stage of the rockburst. If only a one-time pressure relief is used, it cannot adapt to the load characteristics of the continuous development of the rockburst, making it difficult to maintain stable support throughout the entire process. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines. It employs a combination structure of a corrugated pressure-yielding sleeve and axially spaced pressure-yielding sections. Through the phased blocking and release of the pressure-yielding sections by the corrugated pressure-yielding sleeve, multi-stage progressive pressure yielding and graded energy dissipation are achieved in the anchor bolt under axial tension, significantly improving the impact resistance of the support system. It also features a simple structure, ease of processing, and convenient on-site installation. By adaptively adjusting the structural parameters of the corrugated pressure-yielding sleeve and pressure-yielding sections, the controllable design of the anchor bolt's pressure yielding performance can be achieved.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines, comprising a rod body, a tray, a nut, a corrugated pressure-yielding sleeve, a pressure-yielding section, and an anchor body; the front end of the rod body is fixedly connected to the bottom of the borehole through the anchor body; the rear end of the rod body is fixedly connected to the borehole opening through the tray and the nut in sequence; the corrugated pressure-yielding sleeve is located inside the borehole and coaxially fitted on the outside of the rod body, the front end of the corrugated pressure-yielding sleeve is fixedly connected to the bottom of the borehole through the anchor body, and the rear end of the corrugated pressure-yielding sleeve is a free end; the pressure-yielding section is fixedly installed on the rod body, and the pressure-yielding section and the corrugated pressure-yielding sleeve are used together for pressure-yielding and energy absorption.

[0010] A grouting channel is provided at the center of the rod.

[0011] The waveform makes the outer diameter of the pressure sleeve equal to the diameter of the drilled hole.

[0012] Several reduced-diameter sections are evenly distributed on the tube body of the waveform pressure sleeve, and the cross-sectional shape of the reduced-diameter sections is hyperbolic.

[0013] A reinforcing anchor is fixedly installed at the front end of the waveform pressure sleeve.

[0014] The number of pressure relief joints is at least two.

[0015] The number of pressure relief sections is equal to the number of diameter reduction sections, and several pressure relief sections are evenly distributed on the rod body, with the distribution spacing of the pressure relief sections being the same as the distribution spacing of the diameter reduction sections.

[0016] The material of the corrugated pressure sleeve is spring steel. The wall thickness of the corrugated pressure sleeve is 4mm to 6mm. The inner diameter of the straight section is 25mm to 28mm. The minimum inner diameter of the reduced diameter section is 21.5mm to 22.5mm. The axial length of the reduced diameter section is 30mm to 60mm. The distribution spacing of the reduced diameter sections is 60mm to 120mm.

[0017] The outer contour of the pressure joint is ellipsoidal, the material of the pressure joint is high-strength steel, the yield strength of the pressure joint is 600MPa~900MPa, the maximum outer diameter of the pressure joint is 22.5mm~24.0mm, the axial length of the pressure joint is 30mm~50mm, and the distribution spacing of the pressure joint is 60mm~120mm.

[0018] Let P be the ultimate anchorage strength between the rod and the anchor body. a Let the ultimate tensile strength of the rod itself be P. b The waveform allows the ultimate anchoring strength between the pressure sleeve and the reinforcing anchor and the anchor body to be set as P. c Let P1 be the ultimate pressure relief strength of a single pressure relief joint combined with a single diameter reduction section, P2 be the ultimate pressure relief strength of a combination of two pressure relief joints combined with two diameter reduction sections, and so on, until the ultimate pressure relief strength of all pressure relief joints combined with all diameter reduction sections is set to P. n As the number of compression joints and diameter reduction sections increases, the ultimate compression strength increases by an integer multiple, satisfying the following relationship: ① P a <P1<P2<······<P n-1 <P b <P n <P c ; ②, P a = (0.60~0.80) P1; ③ P b = (0.9~0.95) P n ; ④ P n = (0.9~0.95) P c .

[0019] The beneficial effects of this invention are: The multi-stage yielding anchor bolt of the present invention, applicable to rockburst prevention and control in deep mines, adopts a combination structure of corrugated yielding sleeve and axially spaced yielding sections. Through the phased blocking and release of the yielding sections by the corrugated yielding sleeve, the bolt body achieves multi-stage progressive yielding and graded energy dissipation under axial tension, significantly improving the impact resistance of the support system. At the same time, it has the characteristics of simple structure, easy processing, and convenient on-site installation. By adaptively adjusting the structural parameters of the corrugated yielding sleeve and the yielding sections, the controllable design of the anchor bolt's yielding performance can be achieved. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an embodiment of the multi-stage pressure relief anchor bolt (initial stage) applicable to rockburst prevention and control in deep mines according to the present invention; Figure 2This is a schematic diagram of an embodiment of the multi-stage pressure-yielding anchor bolt (first stage pressure-yielding energy absorption stage) for rockburst prevention and control in deep mines according to the present invention; Figure 3 This is a schematic diagram of an embodiment of the multi-stage pressure-yielding anchor bolt (second stage pressure-yielding energy absorption stage) for rockburst prevention and control in deep mines according to the present invention; Figure 4 This is a schematic diagram of an embodiment of the multi-stage pressure-yielding anchor bolt (third-stage pressure-yielding energy absorption stage) for rockburst prevention and control in deep mines according to the present invention; Figure 5 This is a schematic diagram of an embodiment of the multi-stage pressure-yielding anchor bolt (fourth-stage pressure-yielding energy absorption stage) for rockburst prevention and control in deep mines according to the present invention; In the figure, 1—rod body, 2—pallet, 3—nut, 4—wave-shaped relief sleeve, 5—relief section, 6—anchor body, 7—drill hole, 8—reduced diameter section, 9—reinforcing anchor. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] like Figures 1-5 As shown, a multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines includes a rod body 1, a tray 2, a nut 3, a corrugated pressure-yielding sleeve 4, a pressure-yielding section 5, and an anchor body 6. The front end of the rod body 1 is fixedly connected to the bottom of a borehole 7 via the anchor body 6. The tail end of the rod body 1 is fixedly connected to the opening of the borehole 7 via the tray 2 and the nut 3. The corrugated pressure-yielding sleeve 4 is located inside the borehole 7 and coaxially fitted onto the outside of the rod body 1. The front end of the corrugated pressure-yielding sleeve 4 is fixedly connected to the bottom of the borehole 7 via the anchor body 6, and the tail end of the corrugated pressure-yielding sleeve 4 is a free end. The pressure-yielding section 5 is fixedly installed on the rod body 1, and the pressure-yielding section 5 is used in conjunction with the corrugated pressure-yielding sleeve 4 for pressure-yielding and energy absorption.

[0023] A grouting channel is provided at the center of the rod body 1.

[0024] The waveform makes the outer diameter of the pressure sleeve 4 equal to the diameter of the borehole 7.

[0025] Several reduced diameter sections 8 are evenly distributed on the tube body of the waveform pressure sleeve 4, and the cross-sectional shape of the reduced diameter section 8 is hyperbolic.

[0026] A reinforcing anchor 9 is fixedly installed at the front end of the waveform pressure sleeve 4.

[0027] The number of pressure relief sections 5 is at least two.

[0028] The number of pressure relief sections 5 is equal to the number of diameter reduction sections 8. Several pressure relief sections 5 are evenly distributed on the rod body 1, and the distribution spacing of the pressure relief sections 5 is the same as the distribution spacing of the diameter reduction sections 8.

[0029] The material of the corrugated pressure sleeve 4 is spring steel, specifically 35CrMo, 60Si2Mn, etc. The wall thickness of the corrugated pressure sleeve 4 is 4mm to 6mm, the inner diameter of the straight section is 25mm to 28mm, the minimum inner diameter of the reduced diameter section 8 is 21.5mm to 22.5mm, the axial length of the reduced diameter section 8 is 30mm to 60mm, and the distribution spacing of the reduced diameter sections 8 is 60mm to 120mm.

[0030] The outer contour of the pressure joint 5 is ellipsoidal, the material of the pressure joint 5 is high-strength steel, specifically 42CrMo, 40Cr, etc., the yield strength of the pressure joint 5 is 600MPa~900MPa, the maximum outer diameter of the pressure joint 5 is 22.5mm~24.0mm, the axial length of the pressure joint 5 is 30mm~50mm, and the distribution spacing of the pressure joint 5 is 60mm~120mm.

[0031] Let P be the ultimate anchorage strength between rod 1 and anchor body 6. a Let the ultimate tensile strength of rod 1 itself be P. b The waveform allows the ultimate anchoring strength between the pressure sleeve 4 and the reinforcing anchor 9 and the anchor body 6 to be set as P. c Let P1 be the ultimate pressure relief strength of a single pressure relief section 5 combined with a single diameter reduction section 8, P2 be the ultimate pressure relief strength of two pressure relief sections 5 combined with two diameter reduction sections 8, and so on, until the ultimate pressure relief strength of all pressure relief sections 5 combined with all diameter reduction sections 8 is set to P. n As the number of combinations of compression joint 5 and diameter reduction section 8 increases, the ultimate compression strength increases by an integer multiple, satisfying the following relationship: ① P a <P1<P2<······<P n-1 <P b <P n <P c ; ②, P a = (0.60~0.80) P1; ③ P b = (0.9~0.95) P n ; ④ P n = (0.9~0.95) P c .

[0032] The following describes a single use of the present invention with reference to the accompanying drawings: In this embodiment, there are four pressure relief sections 5, and four diameter reduction sections 8 are correspondingly provided on the tube body of the waveform pressure relief sleeve 4. The four pressure relief sections 5 are sequentially referred to as the first pressure relief section, the second pressure relief section, the third pressure relief section and the fourth pressure relief section, and the first pressure relief section is located on the borehole side of the drill hole 7. The four diameter reduction sections 8 are sequentially referred to as the first diameter reduction section, the second diameter reduction section, the third diameter reduction section and the fourth diameter reduction section, and the first diameter reduction section is located on the bottom side of the drill hole 7.

[0033] After the drilling of borehole 7 is completed, the initial assembly consisting of rod 1 and corrugated relief sleeve 4 is sent into borehole 7 and placed in a preset position. In the initial state, the first relief section is located between the first reduced diameter section and the bottom of borehole 7. Then, anchoring grout is injected into the bottom of borehole 7 through the grouting channel in the center of rod 1 until the space between the reinforcing anchor 9 at the front end of corrugated relief sleeve 4 and the bottom of borehole 7 is completely filled with anchoring grout. After the anchoring grout has cured to the design strength, the anchor body 6 is formed, realizing the anchoring and fixing of rod 1 and corrugated relief sleeve 4 in borehole 7.

[0034] After the anchor body 6 is formed, the tray 2 and nut 3 are sequentially installed at the tail end of the rod body 1 on the side of the borehole 7, and the anchor installation work is completed.

[0035] When the surrounding rock undergoes violent instantaneous deformation under high ground stress and rockburst caused by strong disturbance, the rod body 1 and the anchor body 6 first absorb the impact load together to attempt to stop the deformation of the surrounding rock. If the impact load exceeds the ultimate anchoring strength P between the rod body 1 and the anchor body 6, the deformation will continue. a Then, the rod 1 separates from the anchor body 6, and the rod 1 undergoes axial displacement relative to the anchor body 6 and the surrounding rock at the bottom of the borehole 7.

[0036] When rod 1 undergoes axial displacement relative to the surrounding rock at the bottom of borehole 7, the first reduced-diameter section of the wave-shaped pressure-relief sleeve 4 blocks the first pressure-relief joint on rod 1. ① If the impact load at this time exceeds the ultimate pressure-relief strength P1, the first reduced-diameter section and the first pressure-relief joint enter a pressure-relief energy absorption state. The first reduced-diameter section absorbs the impact load through elastic deformation until the first pressure-relief joint completely passes over the first reduced-diameter section and moves between the first and second reduced-diameter sections. The first stage of pressure-relief energy absorption ends, and the first reduced-diameter section automatically restores its shape under the rebound action. ② If the impact load at this time is lower than the ultimate pressure-relief strength P1, the deformation of the surrounding rock can be successfully prevented.

[0037] If the deformation of the surrounding rock is not successfully prevented in the first stage of pressure relief and energy absorption, the rod body 1 will continue to displace axially relative to the surrounding rock at the bottom of borehole 7. The first reduced diameter section of the corrugated pressure relief sleeve 4 will block the second pressure relief section on the rod body 1, and at the same time, the second reduced diameter section of the corrugated pressure relief sleeve 4 will block the first pressure relief section on the rod body 1. ① If the impact load at this time still exceeds the ultimate pressure relief strength P2, the second reduced diameter section and the first pressure relief section will cooperate to enter the pressure relief and energy absorption state. At the same time, the first reduced diameter section and the second pressure relief section will cooperate to enter the pressure relief and energy absorption state. The first reduced diameter section and the second reduced diameter section will absorb the impact load through elastic deformation until the first pressure relief section completely passes over the second reduced diameter section and moves between the second reduced diameter section and the third reduced diameter section. At the same time, the second pressure relief section completely passes over the first reduced diameter section and moves between the first reduced diameter section and the second reduced diameter section. The second stage of pressure relief and energy absorption ends, and the first reduced diameter section and the second reduced diameter section will automatically restore their shape under the rebound action. ② If the impact load at this time is lower than the ultimate compressive strength P2, the deformation of the surrounding rock can be successfully prevented.

[0038] Similarly, if the second stage of yielding and energy absorption fails to prevent deformation of the surrounding rock, the process proceeds to the third stage. If the impact load is resisted in the third stage, the deformation of the surrounding rock can be successfully prevented. If the deformation of the surrounding rock still fails to be prevented in the third stage, the process proceeds to the fourth stage, which is also the final stage in this embodiment.

[0039] During the fourth stage of pressure relief and energy absorption, the first reduced diameter section of the waveform pressure relief sleeve 4 blocks the fourth pressure relief section on the rod 1, the second reduced diameter section of the waveform pressure relief sleeve 4 blocks the third pressure relief section on the rod 1, the third reduced diameter section of the waveform pressure relief sleeve 4 blocks the second pressure relief section on the rod 1, and the fourth reduced diameter section of the waveform pressure relief sleeve 4 blocks the first pressure relief section on the rod 1.

[0040] Since the ultimate tensile strength of rod 1 is lower than the ultimate compressive strength of the combination of all the compressive sections 5 and all the reduced diameter sections 8, the compressive section 5 cannot further exceed the reduced diameter section 8. At this point, the axial displacement of rod 1 ends, and the fourth stage of compressive energy absorption relies on the strength of rod 1 itself to resist the impact load and serves as the last line of defense to continue preventing deformation of the surrounding rock. Ultimately, through multi-stage progressive compressive stress and graded energy dissipation, a significant improvement in the impact resistance of the support system is achieved.

[0041] The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the present invention are included in the scope of protection of the present invention.

Claims

1. A multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines, characterized in that: The system includes a rod body, a tray, a nut, a corrugated pressure-relief sleeve, a pressure-relief section, and an anchor body. The front end of the rod body is fixedly connected to the bottom of the borehole via the anchor body. The rear end of the rod body is fixedly connected to the borehole opening via the tray and nut. The corrugated pressure-relief sleeve is located inside the borehole and coaxially fitted onto the outside of the rod body. The front end of the corrugated pressure-relief sleeve is fixedly connected to the bottom of the borehole via the anchor body, and the rear end of the corrugated pressure-relief sleeve is a free end. The pressure-relief section is fixedly installed on the rod body, and the pressure-relief section is used in conjunction with the corrugated pressure-relief sleeve for pressure relief and energy absorption. A grouting channel is provided at the center of the rod body; the outer diameter of the corrugated pressure-relief sleeve is equal to the borehole diameter; several diameter-reducing sections are evenly distributed on the tube body of the corrugated pressure-relief sleeve, and the cross-sectional shape of the diameter-reducing sections is hyperbolic; a reinforcing anchor is fixedly installed at the front end of the corrugated pressure-relief sleeve; the number of pressure-relief sections is at least two; the number of pressure-relief sections is equal to the number of diameter-reducing sections, and several pressure-relief sections are evenly distributed on the rod body, and the distribution spacing of the pressure-relief sections is the same as the distribution spacing of the diameter-reducing sections; the ultimate anchorage strength between the rod body and the anchor body is set as P. a Let the ultimate tensile strength of the rod itself be P. b The waveform allows the ultimate anchoring strength between the pressure sleeve and the reinforcing anchor and the anchor body to be set as P. c Let P1 be the ultimate pressure relief strength of a single pressure relief joint combined with a single diameter reduction section, P2 be the ultimate pressure relief strength of a combination of two pressure relief joints combined with two diameter reduction sections, and so on, until the ultimate pressure relief strength of all pressure relief joints combined with all diameter reduction sections is set to P. n As the number of compression joints and diameter reduction sections increases, the ultimate compression strength increases by an integer multiple, satisfying the following relationship: ①、P a <P1<P2<······<P n-1 <P b <P n <P c ; ②、P a =(0.60~0.80) P1; ③、P b =(0.9~0.95) P n ; ④、P n =(0.9~0.95) P c 。 2. A multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines according to claim 1, characterized in that: The material of the corrugated pressure sleeve is spring steel. The wall thickness of the corrugated pressure sleeve is 4mm to 6mm. The inner diameter of the straight section is 25mm to 28mm. The minimum inner diameter of the reduced diameter section is 21.5mm to 22.5mm. The axial length of the reduced diameter section is 30mm to 60mm. The distribution spacing of the reduced diameter sections is 60mm to 120mm.

3. A multi-stage pressure-yielding anchor bolt suitable for rockburst prevention and control in deep mines according to claim 1, characterized in that: The outer contour of the pressure joint is ellipsoidal, the material of the pressure joint is high-strength steel, the yield strength of the pressure joint is 600MPa~900MPa, the maximum outer diameter of the pressure joint is 22.5mm~24.0mm, the axial length of the pressure joint is 30mm~50mm, and the distribution spacing of the pressure joint is 60mm~120mm.

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