Protection methods for the bottom structure brow line of lateral collapse in large-diameter deep holes

Abstract

This application provides a method for protecting the bottom structure of a large-diameter deep-hole lateral caving dam, belonging to the field of underground mining technology. This method involves pre-forming a continuous pre-crack above the dam to actively release ground stress and reduce the impact of subsequent blasting, effectively protecting the dam structure. Then, high-strength, high-toughness grouting materials are used to reinforce the pre-crack and surrounding rock fissure areas, improving the integrity and deformation resistance of the dam. High-strength anchor bolts and steel mesh are then used to form an integrated support structure, further enhancing the stability of the dam. Displacement and stress sensors are installed in the stress concentration zone, deformation-sensitive zone, and potential failure zone (near the dam) to monitor the deformation and stress distribution of the dam, allowing for timely understanding of the deformation and fundamentally solving the problems of ground stress and blasting impact on the dam, ensuring mining safety.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology, specifically to a method for protecting the bottom structure of a large-diameter deep-hole lateral collapse. Background Technology

[0002] Large-diameter deep-hole lateral caving is a highly efficient and safe mining method widely used in metal mining, suitable for complex geological conditions such as thick and steeply dipping ore bodies. This method involves placing large-diameter deep holes at the bottom of the ore body and using lateral caving to crush and recover the ore.

[0003] The brow line is a crucial supporting structure between the bottom of the ore body and the goaf, bearing immense ground pressure and blasting impact. In practical applications, protecting the brow line has become a key technical challenge hindering the further promotion of this method. First, with increasing mining depth, ground pressure increases significantly, making the brow line prone to deformation, cracking, and even collapse. Second, the shock waves generated by large-diameter deep-hole blasting directly damage the brow line, affecting its stability. Third, the rock mass at the bottom of the ore body typically contains natural fissures, which further expand after blasting, weakening the integrity of the brow line.

[0004] In existing technologies, most methods for protecting eyebrow lines are passive protection, which cannot fundamentally solve the problem of stress concentration in eyebrow lines.

[0005] Patent application CN116927824A discloses a pre-fracture and post-grouting reinforcement support structure and method for harsh downhole environments. The method involves vertically arranging pre-fracture holes and grouting holes around the rock strata space within the harsh roof. A single-sided open steel pipe, facing the rock strata space, is placed inside each hole. A static fracturing agent is injected into the pre-fracture holes to bring the harsh roof to a critical fracture state. Cement-based material is then injected through the grouting holes to fill the rock fissures. After grouting, the pre-fracture holes and grouting holes are sealed. This invention actively strengthens the roof through human intervention, eliminating instability factors and simplifying subsequent support work. This method effectively solves the problem of traditional support methods that passively accept roof pressure, avoiding safety accidents caused by roof instability. However, this method only involves fracturing the roof with a static fracturing agent followed by grouting, lacking specialized design for blasting impacts, multi-structure collaborative support, and intelligent monitoring functions, thus failing to meet the special requirements for long-term stability of the roofline in high-stress mining environments.

[0006] In view of this, it is necessary to design a protection method for the bottom structure eyebrow line of a large-diameter deep hole lateral mine collapse to solve the above problems. Summary of the Invention

[0007] In view of the technical problems existing in the background art, this application provides a method for protecting the bottom structure of the eyebrow line in large-diameter deep-hole lateral caving. By pre-forming a continuous pre-crack above the eyebrow line, the ground stress is actively released, reducing the impact of subsequent blasting on the eyebrow line. Then, high-strength grouting material is used to reinforce the pre-crack and the surrounding rock mass fracture development area. Finally, an integral support structure is formed by anchor bolts and steel mesh to further improve the stability of the eyebrow line. Displacement sensors and stress sensors are set in the stress concentration area, deformation sensitive area and potential failure area (near the eyebrow line) of the eyebrow line to monitor the deformation and stress distribution of the eyebrow line. This fundamentally solves the problems of ground stress and blasting impact on the eyebrow line and ensures mining safety.

[0008] This application provides a method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving, including the following steps:

[0009] S1, at a position 1-1.5m above the eyebrow line design location, pre-splitting holes are arranged along the eyebrow line direction, and pre-splitting blasting is carried out using a decoupled charge structure to form pre-splitting cracks; wherein, the charge amount is 0.3-0.6kg / m, and a segmented charge method is adopted, with each segment having a length of less than or equal to 2m;

[0010] S2. After pre-splitting blasting, grouting holes are arranged 0.5-1.0m on both sides of the pre-splitting crack and inside the eyebrow line rock mass along the direction of the pre-splitting crack. High-strength grouting material is used to fill the pre-splitting crack and rock mass fissures to reinforce the eyebrow line.

[0011] S3, after grouting reinforcement, anchor bolts and steel mesh are used to form an integral support structure to support the eyebrow line;

[0012] S4. After the support is completed, displacement sensors and stress sensors are installed 0.1-0.5m above and below the designed position of the eyebrow line. The displacement sensors and stress sensors are connected to the data acquisition system to monitor the deformation and stress of the eyebrow line in real time.

[0013] In the embodiments of this application, pre-splitting blasting actively releases ground stress, fundamentally reducing the stress on the brow line and overcoming the limitations of traditional passive protection methods. The use of a decoupled charge structure and segmented charge method allows for precise control of blasting energy, avoiding excessive damage to the brow line. Furthermore, the pre-splitting blasting parameters can be flexibly adjusted according to on-site geological conditions, making it suitable for different mining environments.

[0014] As a further improvement of this application, the pre-splitting holes are arranged as upward blast holes, and the pre-splitting holes form an angle of 10°-30° with the horizontal plane.

[0015] As a further improvement of this application, the spacing of the pre-cracked holes is 0.5-1.0m, the hole diameter is 50-80mm, and the hole depth is 1.2-1.5 times the height of the eyebrow line.

[0016] As a further improvement of this application, depending on the degree of crack development, the spacing of the grouting holes is controlled to be 0.5-1.5m, the hole diameter is 50-80mm, and the hole depth is 1-2m beyond the end of the pre-crack, so as to ensure full crack coverage.

[0017] As a further improvement of this application, the grouting material is a cement-based composite material with a compressive strength greater than or equal to 50 MPa and a tensile strength greater than or equal to 5 MPa.

[0018] As a further improvement of this application, in step S2, the grouting reinforcement adopts a high-pressure grouting process, with a grouting pressure of 1.0-2.0 MPa and a grouting speed of 10-20 L / min.

[0019] Traditional grouting reinforcement methods typically use ordinary cement grout, which has low compressive and tensile strength, making it difficult to effectively fill rock fissures and improve the integrity of the brow line. In the embodiments of this application, a high-strength, high-toughness cement-based composite material is used, and a high-pressure grouting process is employed to fill pre-cracks and rock fissures, significantly improving the integrity and deformation resistance of the brow line.

[0020] As a further improvement to this application, the anchor bolt is a full-length bonded anchor bolt with a diameter of 20-25 mm, a length of 3-5 m, and a spacing of 1.0-1.5 m.

[0021] As a further improvement to this application, the diameter of the reinforcing bars in the steel mesh is 8-12mm, and the mesh spacing is 100-150mm.

[0022] Traditional support methods typically employ single anchor bolts or steel mesh supports, which are difficult to form a cohesive support structure and cannot effectively resist large-scale ground pressure and blasting impacts. In the embodiments of this application, full-length bonded anchor bolts are combined with steel mesh to form a cohesive support structure, significantly improving the stability of the brow line.

[0023] As a further improvement of this application, in step S3, the anchor bolt support uses prestressed anchor bolts, with the prestress being 50%-70% of the anchor bolt's yield strength. Using prestressed anchor bolts further improves the support effect.

[0024] As a further improvement to this application, the steel mesh and the anchor rod are connected by welding or binding.

[0025] The beneficial effects of this application are as follows:

[0026] This application provides a method for protecting the bottom structure of a large-diameter deep-hole lateral caving mine embankment. This method involves pre-forming a continuous pre-crack above the embankment to actively release ground stress and reduce the impact of subsequent blasting, effectively protecting the embankment structure. Then, high-strength, high-toughness grouting materials are used to reinforce the pre-crack and surrounding rock fissure areas, improving the integrity and deformation resistance of the embankment. High-strength anchor bolts and steel mesh are then used to form an integrated support structure, further enhancing the stability of the embankment. Displacement and stress sensors are installed in the stress concentration zone, deformation-sensitive zone, and potential damage zone (0.1-0.5m above and below the designed location of the embankment) to monitor the deformation and stress distribution, allowing for timely understanding of the embankment's deformation and fundamentally solving the problems of ground stress and blasting impact on the embankment, ensuring mining safety.

[0027] This application adopts a systematic protection scheme integrating "pre-splitting blasting - high-pressure grouting - collaborative support - intelligent monitoring". After arranging parallel pre-splitting holes 1.0-1.5m above the eyebrow line and using a decoupled charge structure to accurately release the ground stress, high-pressure grouting is then implemented to fill the cracks, forming a spatial collaborative support system with the full-length bonded anchor rods and steel mesh. Finally, a real-time monitoring system is used to achieve dynamic early warning, forming a full-process active protection of "stress release - overall reinforcement - dynamic monitoring".

[0028] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0030] Figure 1 This is a diagram showing the pre-splitting blasting layout for the eyebrow line.

[0031] Figure 2 for Figure 1 The main view.

[0032] Figure 3 for Figure 1 Side view.

[0033] Figure 4 A schematic diagram of grouting reinforcement for eyebrow lines.

[0034] Figure 5for Figure 4 The main view.

[0035] Figure 6 for Figure 4 Side view.

[0036] Figure 7 This is a layout diagram of the eyebrow support structure.

[0037] Figure 8 for Figure 7 The main view.

[0038] Figure 9 for Figure 7 Side view.

[0039] Figure 10 Layout diagram of the eyebrow line real-time monitoring system.

[0040] Figure 11 This is a comprehensive layout diagram of the protection method for the bottom structure eyebrow line of the large-diameter deep hole lateral collapse mine in this application. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] In existing technologies, the protection methods for the brow line usually adopt passive protection measures (such as reinforced concrete reinforcement or anchor bolt support), which cannot fundamentally solve the problems of ground stress and blasting impact on the brow line.

[0045] This application provides a method for protecting the bottom structure of a large-diameter deep-hole lateral caving mine ridge. A continuous pre-crack is pre-formed above the ridge to actively release ground stress and reduce the impact of subsequent blasting. High-strength grouting material is then used to reinforce the pre-crack and surrounding rock fissure areas. Anchor bolts and steel mesh are then used to form an integrated support structure, further improving the stability of the ridge. Displacement and stress sensors are installed in the stress concentration zone, deformation-sensitive zone, and potential damage zone (near the ridge) to monitor the deformation and stress distribution of the ridge. This fundamentally solves the problems of ground stress and blasting impact on the ridge, ensuring mining safety.

[0046] Please see Figures 1 to 11 As shown in the figure, this application provides a method for protecting the bottom structure eyebrow line of a large-diameter deep hole lateral mine collapse, including the following steps:

[0047] S1, at a location 1-1.5m above the designed position of eyebrow line 1, pre-splitting holes 2 are arranged along the direction of eyebrow line 1. Pre-splitting blasting is performed using a decoupled charge structure to form pre-splitting cracks 31. The charge amount is 0.3-0.6 kg / m, using a segmented charging method, with each segment less than or equal to 2m in length, to control the blasting energy and avoid excessive damage to the eyebrow line. Figures 1 to 3 As shown;

[0048] Among them, the pre-splitting holes 2 are arranged as upward blast holes. Upward blast holes can better control the formation direction of pre-fractures 31, allowing pre-fractures 31 to extend along the brow line 1, effectively releasing the ground stress above the brow line 1. Rock debris and gravel generated after blasting are easier to clean up, reducing secondary damage to the brow line.

[0049] Specifically, the angle of the upward-facing borehole is designed based on the geometry of the brow line and the distribution of ground stress. In this embodiment, the pre-splitting hole 2 forms an angle of 10°-30° with the horizontal plane. An angle that is too small may prevent the pre-splitting crack from fully releasing the ground stress, while an angle that is too large may increase the difficulty of construction.

[0050] In this embodiment of the application, the spacing of the pre-cracked holes 2 is 0.5-1.0m, and the hole diameter is 50-80mm.

[0051] The depth of the pre-cracked hole 2 is 1.2-1.5 times the height of the eyebrow line to ensure that the pre-crack 31 can extend sufficiently above the eyebrow line 1.

[0052] S2, After pre-splitting blasting, grouting holes 43 are arranged 0.5-1.0m on both sides of the pre-splitting crack and inside the rock mass along the direction of the pre-splitting crack. High-strength grouting material is used to fill the pre-splitting crack 31 and the rock mass fissures, forming filled pre-splitting crack 33 and filled fissure 32 to reinforce the brow line. Figures 4 to 6 As shown.

[0053] In this embodiment, depending on the degree of crack development, the spacing of the grouting holes 43 is controlled to be 0.5-1.5 m, the hole diameter is 50-80 mm, and the hole depth is 1-2 m beyond the end of the pre-crack, so as to ensure full crack coverage.

[0054] The grouting material is a cement-based composite material with a compressive strength of not less than 50 MPa and a tensile strength of not less than 5 MPa.

[0055] In this embodiment, the grouting material is injected into the grouting hole 43 through the grouting pipeline 42 connected to the grouting pump 41. The grouting reinforcement adopts a high-pressure grouting process, with a grouting pressure of 1.0-2.0 MPa and a grouting speed of 10-20 L / min. After grouting, the integrity of the rock mass is significantly improved, and the deformation resistance of the brow line is enhanced.

[0056] S3, after grouting reinforcement, anchor bolts 51 and steel mesh 52 are used to form an integral support structure to support the eyebrow line; the steel mesh 52 is connected to the anchor bolts 51 by welding or binding to form an integral support structure, such as Figures 7 to 9 As shown.

[0057] Among them, anchor bolt 51 is a full-length bonded anchor bolt with a diameter of 20-25mm, a length of 3-5m, and a spacing of 1.0-1.5m. The steel mesh 52 has a steel diameter of 8-12mm and a mesh spacing of 100-150mm.

[0058] The anchor bolt support uses prestressed anchor bolts, with a prestress of 50%-70% of the anchor bolt's yield strength.

[0059] S4. After the support is completed, sensors 61 are installed in the stress concentration area, deformation-sensitive area, and potential failure area (near the eyebrow line) along the brow line. Sensors 61 include displacement sensors and stress sensors. These sensors are connected to a data acquisition system to monitor the deformation and stress of the eyebrow line in real time. Figures 10 to 11 As shown.

[0060] The stress concentration zone, deformation-sensitive zone, and potential damage zone of the eyebrow line refer to the area 0.1-0.5m above and below the designed position of the eyebrow line.

[0061] Specifically, displacement sensors (such as LVDT linear displacement gauges) and stress sensors (such as vibrating wire stress gauges) are deployed in the stress concentration zone, deformation-sensitive zone, and potential failure zone of the brow line. These sensors are connected to an explosion-proof data acquisition instrument 62 via armored cables. The data acquisition instrument acquires sensor signals in real time at a sampling frequency of 1-10Hz. After A / D conversion, the signals are transmitted to the surface monitoring center 63 via network. The SCADA system at the surface monitoring center filters and normalizes the data, and uses threshold analysis (e.g., setting a displacement alarm threshold of 5mm and a stress threshold of 80% of the rock mass strength) to achieve automatic early warning. Simultaneously, it predicts deformation trends through time series analysis. All data is stored in a cloud database at 1-minute intervals for subsequent retrospective analysis and further parameter optimization. In this way, the brow line status can be monitored in real time through an intelligent monitoring system, solving the problem of lag in traditional manual inspection.

[0062] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0063] Example 1

[0064] A certain iron mine is mined using the large-diameter deep-hole lateral caving method. The ore body is 50m thick and dips at 60°. Due to the high ground pressure at the bottom of the ore body, the ridge line is prone to deformation and damage. The present invention employs a method for protecting the ridge line at the bottom of the large-diameter deep-hole lateral caving structure. The specific steps are as follows:

[0065] Eyebrow-line pre-splitting blasting: Pre-splitting holes 2 are arranged 1m above the designed position of eyebrow-line 1, along the direction of eyebrow-line 1. The hole spacing is 0.8m, the hole diameter is 60mm, and the hole depth is 6m. Pre-splitting blasting is carried out using a decoupled charge structure, with a charge amount of 0.5kg / m.

[0066] Eyebrow line reinforcement: After pre-splitting blasting, grouting holes 43 are arranged 0.5-1.0m on both sides of the pre-crack and inside the eyebrow line rock mass along the direction of the pre-crack. Cement-based composite material with compressive strength of 60MPa and tensile strength of 6MPa is used to reinforce the eyebrow line by grouting, and the grouting pressure is 1.5MPa.

[0067] Eyebrow line support: After grouting reinforcement, 22mm diameter, 4m long, fully bonded anchor bolts 51 are used to support the eyebrow line, with a spacing of 1.2m between the anchor bolts 51. Simultaneously, 10mm diameter steel mesh 52 with a grid spacing of 120mm is used to support the eyebrow line, and the steel mesh 52 is connected to the anchor bolts 51 to form an integral support structure.

[0068] Eyebrow line monitoring: After the eyebrow line protection construction is completed, displacement sensors and stress sensors are installed in the stress concentration area, deformation sensitive area and potential damage area (near the eyebrow line) of the eyebrow line to monitor the deformation and stress of the eyebrow line in real time.

[0069] After more than a year of production practice, the eyebrow line has not shown any obvious deformation or damage, effectively ensuring mining safety and efficiency.

[0070] Example 2

[0071] A copper mine is mined using the large-diameter deep-hole lateral caving method. The ore body is 40m thick and dips at 70°. Due to the high ground pressure at the bottom of the ore body, the brow line is prone to deformation and damage. The method of this invention is used to protect the brow line, and the specific steps are as follows:

[0072] Eyebrow-line pre-splitting blasting: Pre-splitting holes 2 are arranged 1.2m above the designed position of eyebrow-line 1, along the direction of eyebrow-line 1. The hole spacing is 0.6m, the hole diameter is 70mm, and the hole depth is 5m. Pre-splitting blasting is carried out using a decoupled charge structure, with a charge amount of 0.4kg / m.

[0073] Eyebrow line reinforcement: After pre-splitting blasting, grouting holes 43 are arranged 0.5-1.0m on both sides of the pre-crack and inside the eyebrow line rock mass along the direction of the pre-crack. Cement-based composite material with a compressive strength of 55MPa and a tensile strength of 5.5MPa is used to reinforce the eyebrow line by grouting, and the grouting pressure is 1.8MPa.

[0074] Eyebrow line support: After grouting reinforcement, 25mm diameter, 5m long, fully bonded anchor bolts are used to support the eyebrow line, with an anchor bolt spacing of 1.0m. Simultaneously, a 12mm diameter steel mesh with a 100mm grid spacing is used to support the eyebrow line, and the steel mesh is connected to the anchor bolts to form an integrated support structure.

[0075] Eyebrow line monitoring: After the eyebrow line protection construction is completed, displacement sensors and stress sensors are installed in the stress concentration area, deformation sensitive area and potential damage area (near the eyebrow line) of the eyebrow line to monitor the deformation and stress of the eyebrow line in real time.

[0076] After more than a year of production practice, the eyebrow line has not shown any obvious deformation or damage, effectively ensuring mining safety and efficiency.

[0077] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for protecting the bottom structural brow line of a large-diameter deep-hole lateral caving mine, characterized in that, Includes the following steps: S1, at a position 1-1.5m above the eyebrow line design location, pre-splitting holes are arranged along the eyebrow line direction, and pre-splitting blasting is performed using a decoupled charge structure to form pre-splitting cracks; wherein, the charge amount is 0.3-0.6kg / m, and a segmented charge method is adopted, with each segment having a length of less than or equal to 2m; the pre-splitting holes are arranged as upward blast holes, and the pre-splitting holes form an angle of 10°-30° with the horizontal plane; S2. After pre-splitting blasting, grouting holes are arranged 0.5-1.0m on both sides of the pre-splitting crack and inside the eyebrow line rock mass along the direction of the pre-splitting crack. High-strength grouting material is used to fill the pre-splitting crack and rock mass fissures to reinforce the eyebrow line. S3, after grouting reinforcement, anchor bolts and steel mesh are used to form an integral support structure to support the eyebrow line; S4. After the support is completed, displacement sensors and stress sensors are installed 0.1-0.5m above and below the designed position of the eyebrow line. The displacement sensors and stress sensors are connected to the data acquisition system to monitor the deformation and stress of the eyebrow line in real time.

2. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The pre-cracked holes are spaced 0.5-1.0m apart, with a diameter of 50-80mm and a depth of 1.2-1.5 times the height of the eyebrow line.

3. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The grouting holes are spaced 0.5-1.5m apart, with a diameter of 50-80mm and a depth exceeding the end of the pre-crack by 1-2m.

4. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The grouting material is a cement-based composite material with a compressive strength greater than or equal to 50 MPa and a tensile strength greater than or equal to 5 MPa.

5. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The anchor bolts are full-length bonded anchor bolts with a diameter of 20-25mm, a length of 3-5m, and a spacing of 1.0-1.5m.

6. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The diameter of the steel bars in the steel mesh is 8-12mm, and the mesh spacing is 100-150mm.

7. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, In step S2, the grouting reinforcement adopts a high-pressure grouting process with a grouting pressure of 1.0-2.0 MPa and a grouting speed of 10-20 L / min.

8. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, In step S3, the anchor bolt support adopts prestressed anchor bolts, and the prestress is 50%-70% of the anchor bolt yield strength.

9. The method for protecting the bottom structure brow line of a large-diameter deep hole lateral caving mine according to claim 1, characterized in that, The steel mesh is connected to the anchor rod by welding or binding.

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