Stope drift digging and supporting method

Abstract

The invention discloses a stope drift digging and supporting method, and relates to the technical field of mine stoping. The stope drift tunneling and supporting method comprises the steps that rock drilling blast holes are formed in a tunneling face of a stope drift, shallow hole blasting is adopted, the rock drilling blast holes comprise a plurality of slotting holes, a plurality of auxiliary holes and a plurality of peripheral holes which are formed from inside to outside, and the explosive load of the rock drilling blast holes located above the drift waist line is lower than that of the rock drilling blast holes located below the drift waist line; and the slotting holes are detonated firstly, then the auxiliary holes and the peripheral holes below the drift waist line are detonated, and finally the peripheral holes above the drift waist line are detonated. According to the stope drift digging and supporting method provided by the invention, by controlling the depth of the rock drilling blast holes, optimizing the arrangement of the blast holes, adjusting the explosive loading amount and the detonating sequence and performing low-disturbance controlled blasting, disturbance of blasting energy to surrounding rock of the arch crown of the stope drift is reduced, the risk of collapse of the arch crown is reduced, and the life safety of workers is effectively guaranteed.

Description

Technical Field

[0001] This application relates to the technical field of mine stoping, and in particular to a method for excavating and supporting a stope heading. Background Art

[0002] During the process of mine exploitation, the excavation and support technology is a key link to ensure the safe and stable operation of the stope. Extremely broken ore bodies have characteristics such as loose structure, developed fissures, and low strength, which pose higher requirements for the excavation and support technology.

[0003] In the related art, in the rock drilling and blasting link, the hole depth, hole position, charge amount, detonation method, etc. of the blast holes are not optimized according to the characteristics of extremely broken ore bodies. This unreasonable blasting method seriously damages the structure of the surrounding rock of the heading, further expands the fissures inside the rock, reduces the stability of the surrounding rock, and increases the risk of roof caving. Summary of the Invention

[0004] In view of this, this application provides a method for excavating and supporting a stope heading, aiming to solve one of the technical problems in the prior art.

[0005] To achieve the above object, the technical solution adopted in this application is as follows: In the first aspect, this application provides a method for excavating and supporting a stope heading, including: Arrange rock drilling blast holes on the excavation face of the stope heading, and use short-hole blasting. The rock drilling blast holes include a plurality of cut holes, a plurality of auxiliary holes, and a plurality of perimeter holes. Among them, the plurality of cut holes are arranged around the center of the excavation face, the plurality of auxiliary holes are arranged around the periphery of the plurality of cut holes, and the plurality of perimeter holes are arranged along the contour of the excavation face. The charge amount of the rock drilling blast holes above the heading waistline is lower than that of the rock drilling blast holes below the heading waistline; first detonate the cut holes, then detonate the auxiliary holes and the perimeter holes below the heading waistline, and finally detonate the perimeter holes above the heading waistline; After blasting, clear the blasted loose slag to the position of the heading waistline, and then perform pre-support operation on the roof of the stope heading; After the pre-support operation is completed, remove all the remaining loose slag, and then perform systematic support operation on the entire cross-section of the stope heading.

[0006] In an optional embodiment, the depth of the rock drilling blast holes is 0.8 meters to 1.5 meters; and / or, the charge amount of the rock drilling blast holes above the heading waistline is 1 / 2 to 2 / 3 of the charge amount of the rock drilling blast holes below the heading waistline.

[0007] In an alternative embodiment, the auxiliary holes are arranged below the mid - crown of the driving face; and / or, the hole spacing of the peripheral holes at the crown of the driving face is smaller than that of the peripheral holes at the side wall of the driving face, and the hole spacing of the peripheral holes at the crown of the driving face is also smaller than that of the peripheral holes at the floor of the driving face.

[0008] In an alternative embodiment, relief holes are drilled at the central position of the plurality of cut holes; and / or, the hole angle of the peripheral holes deflects outward by 1° - 3°.

[0009] In an alternative embodiment, the pre - support operation for the crown of the stope drift includes: Spraying special concrete with a thickness of 10 cm - 15 cm on the surface of the crown of the stope drift to form a special concrete layer for pre - support on the crown surface.

[0010] In an alternative embodiment, the special concrete is made of crushed stone, sand, water, accelerator and cementitious material, and the special concrete is sprayed on the surface of the crown of the stope drift by a dry shotcreting machine to form the special concrete layer.

[0011] In an alternative embodiment, the systematic support operation for the full section of the stope drift includes: Drilling cable bolt holes from the center of the surface of the crown of the stope drift towards the deep ore body, and drilling cable bolt holes from the surface at the shoulder angle of the crown of the stope drift towards the deep ore body, and installing deep - point prestressed cable bolts in the cable bolt holes; Hanging a wire mesh and a steel strip with the help of the deep - point prestressed cable bolts; Drilling bolt holes on the surface of the crown and the two side walls of the stope drift, and installing systematic bolts in the bolt holes; Spraying ordinary concrete with a thickness of 5 cm - 10 cm on the full section.

[0012] In an alternative embodiment, installing the deep - point prestressed cable bolt in the cable bolt hole includes: Placing the anchoring agent at the bottom of the cable bolt hole; Using a cable bolt drill rig to drive the deep - point prestressed cable bolt to rotate and advance in the cable bolt hole, and the deep - point prestressed cable bolt stirs the anchoring agent to cure it; After curing, tension the deep - point prestressed cable bolt to make the deep - point prestressed cable bolt tensioned to a preset locking force value; Injecting cement slurry into the cable bolt hole to form a cement slurry stone body.

[0013] In an alternative embodiment, the deep - point prestressed cable bolt includes a steel strand, a locking device, a tray, a unit anchor point, an isolation pipe and an anchoring agent; Among them, after curing, the anchoring agent is fixed at the bottom of the cable bolt hole. The steel strand is threaded through the cable bolt hole, and one end of the steel strand is fixedly connected to the cured anchoring agent, and the other end is exposed out of the cable bolt hole. Unit anchor points are arranged on the steel strand, and the unit anchor points are close to the anchoring agent. The locking device and the tray are installed at the orifice of the cable bolt hole to tension and lock the steel strand. The isolation pipe is wrapped on the outer surface of the steel strand except for the unit anchor points.

[0014] In an alternative embodiment, the depth of the cable bolt hole is 5 m to 8 m, and no less than 80% of the hole depth of the cable bolt holes at the shoulder angle of the vault is located in the ore body on the side away from the drift on the upward extension line of the side wall of the drift; The depth of the bolt hole is 2 m to 3 m. The number of systematic bolts arranged at the vault is no less than 4, and the number of systematic bolts arranged corresponding to each side wall is no less than 2; The deep anchor point prestressed cable bolts are arranged in the same row as the systematic bolts, and are arranged in multiple rows along the heading direction of the drift. The row spacing is not greater than the depth of the cyclic advance of the drift.

[0015] Compared with the prior art, the beneficial effect of the present application is that the present application proposes a method for driving and supporting a stope drift, including arranging drilling blast holes on the driving face of the stope drift and using short-hole blasting. The relatively shallow hole depth makes the charge amount of the blast holes smaller, and the generated vibration and shock wave are smaller, reducing the impact and vibration of blasting on the surrounding rock and the vault P2 at the driving face of the stope; The drilling blast holes include multiple cut holes, multiple auxiliary holes and multiple perimeter holes. Among them, multiple cut holes are arranged around the center of the driving face, multiple auxiliary holes are arranged around the periphery of the multiple cut holes, and multiple perimeter holes are arranged along the contour of the driving face. The charge amount of the drilling blast holes above the waistline of the drift is lower than that of the drilling blast holes below the waistline of the drift, reducing the blasting energy of each drilling blast hole near the vault and reducing the impact and vibration of blasting on the surrounding rock and the vault P2 at the stope drift; The cut holes are detonated first, then the auxiliary holes and the perimeter holes below the waistline of the drift are detonated, and finally the perimeter holes above the waistline of the drift are detonated. Blasting in this way from the inside out enables the blasting energy to be released orderly, reducing the disturbance of the blasting energy to the surrounding rock of the vault P2 of the stope drift.

[0016] Aiming at the characteristics of extremely broken ore bodies, such as loose structure, developed fissures and low strength, low-disturbance controlled blasting is carried out by controlling the depth of drilling blast holes, optimizing the blast hole layout, adjusting the charge amount and the detonation sequence, enabling the blasting energy to be released orderly, reducing the disturbance of the blasting energy to the surrounding rock of the vault of the stope drift, reducing the risk of vault collapse, and effectively ensuring the safety of the staff.

[0017] After blasting, the loosened slag that has fallen is cleared to the waist line of the drift, and then pre-support operation is carried out on the vault of the stope drift. This can quickly and timely provide support resistance to control the deformation of the vault P2 and reduce the situation of large-area collapse of the vault P2.

[0018] After the pre-support operation is completed, all the remaining loosened slag that has fallen is cleared, and then systematic support operation is carried out on the full section of the stope drift. This can enhance the support strength, form an effective common load-bearing system with the surrounding rock, and improve the stability of the drift during the mining process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as a limitation on the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 Shows the flow chart of the stope drift excavation and support method in some embodiments of the present application; Figure 2 Shows the layout diagram of the drilling blast holes on the excavation face in some embodiments of the present application; Figure 3 Shows the cross-sectional structure diagram of the stope drift after pre-support operation in some embodiments of the present application; Figure 4 Shows the cross-sectional structure diagram of the stope drift after systematic support operation in some embodiments of the present application; Figure 5 Shows the installation structure diagram of the steel mesh in some embodiments of the present application; Figure 6 Shows the installation structure diagram of the steel strip in some embodiments of the present application; Figure 7 Shows the structure diagram of the prestressed anchor cable of the deep anchor point in some embodiments of the present application; Figure 8 Shows the unfolded structure diagram of the surface of the stope drift vault in some embodiments of the present application; Figure 9 Shows the excavation cycle diagram of the stope drift in some embodiments of the present application.

[0021] Description of main component symbols: 11 - empty hole; 12 - cut hole; 13 - auxiliary hole; 14 - perimeter hole; 2 - special concrete layer; 3 - deep anchor prestressed cable; 31 - steel strand; 32 - locking device; 33 - tray; 34 - anchoring agent; 35 - unit anchor point; 36 - isolation pipe; 37 - cement slurry stone body; 38 - cable hole; 4 - steel mesh; 5 - steel strip; 6 - system bolt; 7 - ordinary concrete layer; P1 - heading waistline; P2 - arch crown; P3 - side wall; P4 - floor; P5 - shoulder corner. Detailed implementation manners

[0022] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as a limitation to the present application.

[0023] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0024] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0025] In the present application, unless otherwise clearly specified and limited, the terms "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0026] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply indicates that the horizontal height of the first feature is less than that of the second feature.

[0027] The extremely fragmented ore body has characteristics such as loose structure, developed fissures, and low strength. In actual mining, safety accidents such as large - area collapses of the heading arch and rib spalling of the surrounding rock often occur due to excessive blasting disturbance, seriously threatening the lives of operating personnel.

[0028] The reasons for excessive blasting disturbance are as follows: For example, in the rock - drilling and blasting link, the depth of conventional rock - drilling blast holes is relatively large, resulting in too concentrated energy generated by the explosive during blasting, which causes strong impact and vibration on the heading arch and the surrounding rock; for example, in the rock - drilling and blasting link, the hole positions, the distribution of explosive charges in the blast holes, or the detonation sequence are not optimized for the characteristics of the extremely fragmented ore body, causing damage to the structure of the surrounding rock of the heading and greatly reducing the stability of the surrounding rock.

[0029] In response to the above problems, as Figure 1 shown, an embodiment of the present application provides a method for driving and supporting a stope heading, which is mainly used for driving and supporting the heading of an extremely fragmented stope, reducing the disturbance of blasting to the heading arch and the surrounding rock of the extremely fragmented ore body, and providing a reliable guarantee for the efficient and safe mining of the extremely fragmented stope.

[0030] As Figure 1 and Figure 2 shown, the method for driving and supporting a stope heading of the present application includes: Step S10, arranging rock - drilling blast holes on the driving face of the stope heading, using short - hole blasting. The rock - drilling blast holes include a plurality of cut holes 12, a plurality of auxiliary holes 13, and a plurality of perimeter holes 14. Among them, the plurality of cut holes 12 are arranged in the middle of the driving face, and the plurality of cut holes 12 are arranged around the center of the driving face. The plurality of auxiliary holes 13 are arranged around the periphery of the plurality of cut holes 12, and the plurality of perimeter holes 14 are arranged along the contour of the driving face. The explosive charge of the rock - drilling blast holes above the stope heading waistline P1 is lower than that of the rock - drilling blast holes below the stope heading waistline P1; the cut holes 12 are detonated first, then the auxiliary holes 13 and the perimeter holes 14 below the stope heading waistline P1 are detonated, and finally the perimeter holes 14 above the stope heading waistline P1 are detonated.

[0031] The driving face refers to the working face where excavation operations are carried out.

[0032] Short-hole blasting achieves the fragmentation of rock or soil by loading explosives in relatively shallow drill holes and detonating them. The depth of the blast holes in short-hole blasting is less than 5 meters. The relatively shallow hole depth reduces the disturbance of the extremely fragmented rock mass during the drilling of the rock-drilling blast holes. The relatively shallow hole depth also results in a smaller amount of explosive charge in the blast holes, generating less vibration and shock wave, and reducing the impact and vibration of the blasting on the surrounding rock and the arch top P2 of the stope.

[0033] In view of the characteristics of extremely fragmented ore bodies, such as loose structure, developed fissures, and low strength, the explosive charge of the rock-drilling blast holes above the drift waistline P1 is also set to be lower than that of the rock-drilling blast holes below the drift waistline P1, so as to reduce the disturbance and damage of the blasting to the drift arch top P2.

[0034] The drift waistline P1 refers to a horizontal reference line set during the roadway driving process to ensure that the slope and direction of the drift meet the design requirements. The main function of the drift waistline is to guide the driving direction and slope of the drift and ensure that the roadway is constructed according to the design requirements.

[0035] In one embodiment, as Figure 2 shown, the cut hole 12 is located in the middle of the driving face and below the drift waistline P1. Above the drift waistline P1 are the arch top P2 and part of the side wall P3. Part of the auxiliary holes 13 and part of the perimeter holes 14 are located above the drift waistline P1, and the cut hole 12, part of the auxiliary holes 13, and part of the perimeter holes 14 are located below the drift waistline P1.

[0036] The explosive charge of the auxiliary holes 13 and perimeter holes 14 located above the drift waistline P1 is less than that of the cut hole 12, auxiliary holes 13, and perimeter holes 14 located below the drift waistline P1. This reduces the blasting energy of each rock-drilling blast hole near the arch top P2 and decreases the impact and vibration of the blasting on the surrounding rock and the arch top P2 of the stope.

[0037] The cut hole 12 is detonated first, and then the auxiliary holes 13 and perimeter holes 14 are detonated. Blasting in this way from the inside out enables the orderly release of the blasting energy and reduces the disturbance of the blasting energy to the surrounding rock of the stope drift arch top P2.

[0038] The perimeter holes 14 below the drift waistline P1 are detonated first, and then the perimeter holes 14 above the drift waistline P1 are detonated. Specifically, detonating the perimeter holes 14 below the drift waistline P1 first can provide a free face for the upper rock, making it easier for the rock to collapse along the free face when the perimeter holes 14 above the drift waistline P1 are blasted, reducing the rock clamping effect and improving the fragmentation efficiency.

[0039] In addition, after the peripheral holes 14 below the drift waistline P1 are blasted, a stable foundation contour can be formed, providing guidance for the blasting of the peripheral holes 14 above the drift waistline P1 and avoiding overbreak caused by premature caving of the top rock. The broken rock pile generated by the blasting of the peripheral holes 14 below the drift waistline P1 can serve as a natural barrier for the blasting of the peripheral holes above the drift waistline P1, restricting the throwing range of flying rocks and improving the safety of the blasting operation.

[0040] Step S20: After the blasting is completed, the loose slag that has fallen is cleared to the position of the drift waistline P1, and then pre-support operation is carried out on the arch top of the stope drift. In this way, the support resistance can be provided quickly and in a timely manner to control the deformation of the arch top P2 and reduce the occurrence of large-area collapse of the arch top P2.

[0041] Step S30: After the pre-support operation is completed, all the remaining loose slag that has fallen is cleared, and then systematic support operation is carried out on the full section of the stope drift.

[0042] In this way, the support strength can be enhanced, an effective common bearing system can be formed with the surrounding rock, and the stability of the drift during the mining process can be improved.

[0043] In some embodiments, the depth of the drilling blast holes is 0.8 m to 1.5 m.

[0044] The depth of each drilling blast hole is the same, and the depth of the drilling blast holes is 0.8 m, 0.9 m, 1.0 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, etc., not limited to the depths in the examples. By reasonably setting the hole depth and controlling the charge amount of the blast holes, the vibration and shock wave generated by the explosion of the explosive can be reduced, the impact and vibration on the surrounding rock and the arch top P2 of the drift can be lowered, and low-disturbance blasting can be achieved.

[0045] In some embodiments, the charge amount of the drilling blast holes above the drift waistline P1 is 1 / 2 to 2 / 3 of the charge amount of the drilling blast holes below the drift waistline.

[0046] The charge amounts of the auxiliary holes 13 and the peripheral holes 14 above the drift waistline P1 are 0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67 of the charge amounts of the cut holes 12, the auxiliary holes 13 and the peripheral holes 14 below the drift waistline P1. When the ratio is less than 1 / 2, the blasting energy is too small, reducing the blasting forming efficiency of the stope drift; when the ratio is higher than 2 / 3, the blasting energy of each drilling blast hole near the arch top is larger, enhancing the impact and vibration of the blasting on the surrounding rock and the arch top P2 of the stope.

[0047] In some embodiments, such as Figure 2As shown, the hole spacing of the peripheral holes 14 at the vault P2 of the driving face is smaller than that of the peripheral holes 14 at the side wall P3 of the driving face, and the hole spacing of the peripheral holes 14 at the vault P2 of the driving face is also smaller than that of the peripheral holes 14 at the floor P4 of the driving face. The hole density of the peripheral holes 14 at the vault P2 of the driving face is greater than that of the peripheral holes 14 at the side wall P3, and is also greater than that of the peripheral holes 14 at the floor P4. By increasing the density of the blast holes at the vault P2, sufficient blasting energy is provided to improve the blasting forming efficiency; by increasing the number of blast holes, the blasting impact on the vault P2 is dispersed, so that the vibration and shock wave generated by the explosion of the explosive in each blast hole are smaller, and the impact and vibration of the blasting on the vault P2 of the drift are reduced.

[0048] In short, aiming at the characteristics of extremely broken ore bodies, such as loose structure, developed fissures, and low strength, the number of blast holes at the vault P2 is increased, and the charge amount of the explosive in each blast hole is reduced to improve the blasting efficiency, form the vault P2 in one blasting, improve the blasting effect, and also reduce the impact and vibration of the blasting on the vault P2 of the drift.

[0049] In some embodiments, the auxiliary holes 13 are arranged below the vault P2 of the driving face.

[0050] As Figure 2 shown, in the direction from the vault P2 to the floor P4 of the drift, the first row of auxiliary holes 13 is arranged below the vault P2 to reduce the disturbance of the surrounding rock of the vault P2 by the blasting.

[0051] In some embodiments, a relief hole 11 is drilled at the center position of the plurality of cut holes 12.

[0052] As Figure 2 shown, the number of cut holes 12 is multiple, and the multiple cut holes 12 are arranged around the relief hole 11. By arranging the relief hole 11, the temporary space formed by the blasting of the cut holes 12 is compensated, the blasting efficiency is improved, and the blasting effect is improved.

[0053] When the number of relief holes 11 is one, the axis of the relief hole 11 coincides with the central axis of the driving face. When the number of relief holes 11 is multiple, the multiple relief holes 11 are arranged around the central axis of the driving face.

[0054] The depth of the relief hole 11 is controlled within 0.8 m to 1.5 m. The depth of the relief hole 11 is the same as that of the charged blast holes, and the depth of the relief hole 11 is 0.8 m, 0.9 m, 1.0 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, etc., and is not limited to the depths in the examples.

[0055] In some embodiments, the blast hole angle of the peripheral holes 14 deflects outward by 1° to 3°.

[0056] Since the drilling machine cannot drill holes along the edge of the driving face, a certain distance is reserved at the edge of the driving face for easy drilling.

[0057] Outward deflection means that the axis of the blast hole deflects away from the center of the driving face. Such a hole layout method facilitates blasting to form a driving face that meets the design size requirements.

[0058] In one embodiment, the blast holes at the crown P2 of the peripheral holes 14 deflect upward by 1°, 1.5°, 2°, 2.5°, 3°; the blast holes at the side wall P3 deflect outward by 1°, 1.5°, 2°, 2.5°, 3°; the blast holes at the floor P4 deflect downward by 1°, 1.5°, 2°, 2.5°, 3°.

[0059] The empty holes 11, cut holes 12, and auxiliary holes 13 are all vertical blast holes.

[0060] In some embodiments, the cut holes 12, auxiliary holes 13, and peripheral holes 14 are charged continuously or at intervals, and the hole openings are blocked with gunite. The initiation method uses digital detonators to initiate at the bottom of the holes. Two detonators are arranged in the cut holes 12, and single detonators are arranged in the remaining rock drilling holes.

[0061] In some embodiments, the pre-support operation for the crown of the stope drift includes: spraying a special concrete layer with a thickness of 10 cm to 15 cm on the surface of the crown P2 of the stope drift to form a special concrete layer 2 for pre-support on the surface of the crown P2.

[0062] As Figure 3 shown, by forming a high-strength special concrete layer 2 on the surface of the crown P2, the exposure time of the crown P2 is shortened, and the initial deformation of the crown P2 and the surrounding rock is inhibited in a timely manner.

[0063] In some embodiments, the special concrete is made of crushed stone, sand, water, accelerator, and cementitious material. The special concrete is sprayed on the surface of the crown P2 of the stope drift by a dry shotcrete machine to form a special concrete layer 2. The strength of the special concrete layer 2 is not less than 10 MPa two hours after spraying.

[0064] In one embodiment, the particle size range of the crushed stone is 5 - 15 mm (corresponding to about 3 mesh - 10 mesh of Tyler sieve).

[0065] The sand uses medium and coarse sand composite gradation. Among them, the proportion of coarse sand (1.18 - 4.75 mm) is 40 - 50%; the proportion of medium sand (0.6 - 1.18 mm) is 30 - 40%; the proportion of fine sand (0.15 - 0.6 mm) is 10 - 20%.

[0066] The cementitious material consists of bauxite clinker and P.O42.5 cement, where the proportion of bauxite clinker is 10 - 20%, and the proportion of P.O42.5 cement is 80 - 90%.

[0067] The accelerating agent is sodium metaaluminate, and the accelerating agent should be dissolved in water separately and stored before spraying.

[0068] The shotcreting process is as follows: during the dry shotcreting construction, the cementitious material is stirred and mixed with crushed stones and sand, and the accelerating agent is added to the water for shotcreting and dissolved. It can achieve the initial setting of the special concrete within 5 minutes after spraying, achieving the purpose of rapid shotcreting support.

[0069] In one embodiment, the mixing ratios of crushed stones, sand, water, accelerating agent and cementitious material are as follows in the table:

[0070] After on-site detection, the special concrete layer 2 formed after dry shotcreting construction solidified 2 minutes after spraying, and the average compressive strength of the special concrete layer 2 measured 120 minutes after spraying exceeded 10 MPa.

[0071] The thickness of the special concrete layer 2 is 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, etc., and the thickness is not limited to the examples. When the thickness is less than 10 cm, the support strength of the special concrete layer 2 is reduced; when the thickness is greater than 15 cm, the special concrete layer 2 is too thick and prone to cracking.

[0072] In some embodiments, systematic support operations are carried out on the full section of the stope drift, including: As Figure 4 shown, in step S31, cable anchor holes 38 are drilled from the center of the surface of the crown P2 of the stope drift towards the deep ore body, and cable anchor holes 38 are also drilled from the surface of the shoulder angle P5 of the crown P2 of the stope drift towards the deep ore body of the crown P2, and deep anchor point prestressed cable bolts 3 are installed in the cable anchor holes 38.

[0073] After all mucking is completed, and 1 to 2 hours after spraying the special concrete, the cable anchor holes 38 are drilled again.

[0074] The principle of the deep anchor point prestressed cable bolt 3 is to enhance the stability of the structure to be reinforced by applying prestress. In actual engineering, it is usually necessary to cooperate with a steel mesh and steel straps to further enhance the reinforcement effect. The steel mesh can provide shear resistance within the plane. The steel straps play a role in locally strengthening or dispersing the load of the cable bolt.

[0075] Combined with referring to Figure 4 and Figure 5 , in step S32, a steel mesh 4 and steel straps 5 are hung with the help of the deep anchor point prestressed cable bolt 3.

[0076] As Figure 4 shown, in step S33, bolt holes are drilled on the surface of the crown P2 of the stope drift and the surfaces of the two side walls P3, and systematic bolts 6 are installed in the bolt holes.

[0077] During the construction of the access road, especially under the conditions of soft or fractured surrounding rock, in order to improve the safety and stability of the access road structure, it is necessary to drill bolt holes at the crown P2 and the side wall P3 and install the systematic bolts 6. By applying prestress, the systematic bolts 6 tightly combine the surrounding rock with the lining to form a whole, thereby enhancing the self-stabilizing ability of the surrounding rock.

[0078] Step S34, spray ordinary concrete with a thickness of 5 cm to 10 cm on the entire section.

[0079] As Figure 4 shown, the grade of the ordinary concrete sprayed on the entire section is C20 or above, and an ordinary concrete layer 7 is formed on the entire section.

[0080] The thickness of the ordinary concrete layer 7 is 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, etc., and is not limited to the thickness of the example. When the thickness is less than 5 cm, the support strength of the ordinary concrete layer 7 is reduced; when the thickness is greater than 10 cm, the ordinary concrete layer 7 has a large thickness and is prone to cracking.

[0081] Shotcreting the entire section is a method of spraying a concrete mixture onto the surface of the surrounding rock of a tunnel or underground space through high pressure to form a uniform concrete protective layer. Such a structure can significantly improve the stability of the surrounding rock, prevent the rock mass from loosening and collapsing, and provide good waterproof performance.

[0082] In this application, a special concrete layer 2 is first formed on the surface of the crown P2 of the stope access road to shorten the exposure time of the crown P2 and timely inhibit the initial deformation of the top wall surface and the surrounding rock. Then, a full-section systematic support is set up to significantly improve the overall support effect and reduce the deformation of the surrounding rock.

[0083] In some embodiments, installing the deep anchor point prestressed cable 3 in the cable anchor hole 38 includes: Step S311, place the anchoring agent 34 at the bottom of the cable anchor hole 38.

[0084] Step S312, use the cable anchor drill to drive the deep anchor point prestressed cable 3 to rotate and advance in the cable anchor hole 38, and the deep anchor point prestressed cable 3 stirs the anchoring agent 34 to make it solidify.

[0085] In one embodiment, the anchoring agent 34 is a resin anchoring agent, which consists of two parts: resin glue and curing agent. These two parts undergo a chemical reaction when mixed and quickly solidify to form a high-strength bonding material. By quickly solidifying through a chemical reaction, the deep anchor point prestressed cable 3 is tightly combined with the hole wall of the cable anchor hole 38 to provide a high-strength anchoring effect.

[0086] Step S313: After curing, tension the deep anchor prestressed cable 3 until the deep anchor prestressed cable 3 is tensioned to a preset locking force value.

[0087] Specifically, use a tensioning machine for the tensioning operation and tension it to the locking force value according to the design requirements.

[0088] Exemplarily, the designed locking force value is 300 KN.

[0089] Step S314: Inject cement slurry into the cable hole 38 to form a cement slurry stone body 37.

[0090] During operation, inject cement slurry into the cable hole 38 to fill the pores between the deep anchor prestressed cable 3 and the hole wall of the cable hole 38. After the cement slurry cures, the formed cement slurry stone body 37 wraps the isolation pipe 36 inside.

[0091] In some embodiments, the deep anchor prestressed cable 3 includes a steel strand 31, a locking device 32, a tray 33, a unit anchor 35, an isolation pipe 36, and an anchoring agent 34.

[0092] As Figure 7 shown, after the anchoring agent 34 cures, it is fixed at the bottom of the cable hole 38. The steel strand 31 passes through the cable hole 38, and one end of the steel strand 31 is fixedly connected to the cured anchoring agent 34, and the other end is exposed outside the cable hole 38.

[0093] As Figure 7 shown, a unit anchor 35 is arranged on the steel strand 31. The unit anchor 35 is close to the anchoring agent 34. The unit anchor 35 is arranged around the steel strand 31. The unit anchor 35 is connected to the steel strand 31 by friction and threading, so that a firm connection can be established between the unit anchor 35 and the steel strand 31 to ensure that there is no relative displacement between the two during the force application process.

[0094] Exemplarily, the unit anchor 35 is made of No. 45 steel and is a circular extrusion steel body.

[0095] As Figure 7 shown, the locking device 32 and the tray 33 are installed at the orifice of the cable hole 38 to tension and lock the steel strand 31.

[0096] After the steel strand 31 is tensioned by the locking device 32, the locking device 32 locks the steel strand 31 and is supported against the surrounding rock surface to prevent the steel strand 31 from rebounding and keep the steel strand 31 in a tensioned state. The tray 33 can disperse the force and prevent the locking device 32 from sinking easily.

[0097] As Figure 7 shown, the isolation pipe 36 wraps the outer surface of the steel strand 31 except for the unit anchor 35.

[0098] By setting the isolation pipe 36 to tightly wrap the outer surface of the steel strand 31 except for the unit anchor point 35, an isolation barrier is constructed between the outer surface of the steel strand 31 and the cement paste stone body 37. The isolation pipe 36 can effectively block the contact between external erosion factors and the outer surface of the steel strand 31, significantly reduce the possibility of corrosion on the outer surface of the steel strand 31, prevent the problem of weakening of the anchoring force caused by the corrosion of the outer surface of the steel strand 31, thereby reducing the frequency of engineering maintenance and cost investment.

[0099] Exemplarily, the isolation pipe 36 is made of a PVC (polyvinyl chloride) hose.

[0100] Furthermore, the thickness of the isolation pipe 36 is 7 mm to 10 mm.

[0101] It can be understood that the thickness of the isolation pipe 36 is not less than 7 mm to ensure that the isolation pipe 36 itself has sufficient strength and is not easily damaged. At the same time, the thickness of the isolation pipe 36 is not greater than 10 mm to avoid the isolation pipe 36 occupying too much space in the anchor cable hole 38 and ensure that the size of the cement paste stone body 37 meets the design requirements.

[0102] Optionally, the thickness of the isolation pipe 36 can be 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm or any value between 7 mm and 10 mm.

[0103] By inserting the deep anchor point prestressed anchor cable 3 into the anchor cable hole 38, a firm connection is formed between the anchor cable and the surrounding rock. When potential cracks appear in the surrounding rock and gradually expand, causing the cracks to tear the cement paste stone body 37 and then conduct to the steel strand 31, the unit anchor point 35 can quickly respond, actively and effectively limit the further cracking and displacement of the cracks, and significantly improve the reliability and stability of the anchoring.

[0104] As Figure 4 shown, in one embodiment, the number of anchor cable holes 38 is three. One anchor cable hole 38 is located in the middle of the vault P2, and the anchor cable hole 38 is drilled from the center of the surface of the vault P2 into the deep ore body; one anchor cable hole 38 is located at the left shoulder angle P5 of the vault P2, and the anchor cable hole 38 is drilled from the surface of the left shoulder angle P5 of the vault P2 into the deep ore body; the remaining one anchor cable hole 38 is located at the right shoulder angle P5 of the vault P2, and the anchor cable hole 38 is drilled from the surface of the right shoulder angle P5 of the vault P2 into the deep ore body.

[0105] It should be noted that, as Figure 4 shown, for the anchor cable holes 38 provided at the shoulder angle P5, at least 80% of the hole depth of the anchor cable holes 38 is located in the ore body on the side away from the drift on the extension line of the side wall P3 of the drift, so that the deep anchor point prestressed anchor cables 3 provided in the anchor cable holes 38 are connected to the surrounding deep ore bodies to improve the stability of the ore rock.

[0106] The depth of the cable anchor hole 38 is 5 m to 8 m. Specifically, the depth of the cable anchor hole 38 is 5 m, 5.5 m, 6 m, 6.5 m, 7 m, 7.5 m, 8 m, etc., and is not limited to the depths in the examples.

[0107] In some embodiments, the depth of the bolt holes is 2 m to 3 m, the number of systematic bolts 6 arranged at the vault P2 is not less than 4, and the number of systematic bolts 6 arranged corresponding to each side wall P3 is not less than 2.

[0108] As Figure 4 shown, the number of bolt holes is 8. Among them, 4 bolt holes are arranged at the vault P2, and the bolt holes located at the vault P2 are arranged on both sides of the cable anchor hole 38 at the shoulder angle part P5. Two bolt holes are arranged on the left side wall P3, and the remaining two bolt holes are arranged on the right side wall P3. The 8 bolt holes are symmetrically arranged.

[0109] In some embodiments, as Figure 8 and Figure 9 shown, the deep anchor point prestressed cable 3 and the systematic bolt 6 are arranged in the same row and are arranged in multiple rows along the heading direction of the drift. The row spacing is L1, and the depth of the cyclic advance of the drift is L2, satisfying: L1 ≤ L2. The deep anchor point prestressed cables 3 arranged in multiple rows and the systematic bolts 6 can form a multi-level "rigid-flexible combination" support system, indirectly controlling the pressure on the vault P2 by enhancing the stability of the two side walls P3 of the deep rock mass, and improving the stability of the vault P2.

[0110] It also controls that the support row spacing after each excavation does not exceed the excavation depth, enabling the support structure to timely cover the newly exposed surrounding rock, reducing the exposure time and length of the unsupported section, and enhancing the stability of the surrounding rock.

[0111] Please refer to Figures 2 to 9 below, and a specific embodiment is used to illustrate the stope drift excavation and support method of the present application: The width of the extremely broken stope drift is 3.2 m, the height is 3.1 m, and the drift spacing and the sectional height are both 15 m.

[0112] The depth of the drilling blast hole is 1.2 m, and the diameter is 10 mm.

[0113] One empty hole 11 is located at the center of the heading face, 1.25 m from the floor. 4 cut holes 12 are evenly arranged on the periphery of the empty hole 11, and the 4 cut holes 12 are evenly arranged around the empty hole 11. As Figure 2 shown, the horizontal and vertical spacings between the empty hole 11 and the cut holes 12 are both 0.15 m.

[0114] As Figure 2As shown in the figure, 18 peripheral holes 14 are arranged along the contour line of the driving face, among which 10 are evenly arranged along the contour of the arch top P2, 2 are arranged on each side wall P3 contour, and 4 are evenly arranged along the contour of the floor P4. The hole spacing of the peripheral holes 14 located on the same side wall P3 contour is 0.8 m, and the hole spacing of the peripheral holes 14 located on the floor P4 contour is 1.0 m.

[0115] Two rows of 4 auxiliary holes 13 are arranged. The auxiliary holes 13 are arranged in the same row as the peripheral holes 14 at the side wall P3, and the spacing between the auxiliary holes 13 in the same row is 1.0 m.

[0116] Two auxiliary holes 13 ( Figure 2 hollow auxiliary holes 13) are located above the roadway waistline P1, and the other two auxiliary holes 13 ( Figure 2 solid auxiliary holes 13) are located below the roadway waistline P1.

[0117] The charge amount of the peripheral holes 14 and auxiliary holes 13 above the waistline is 1 / 2 of the charge amount of the peripheral holes 14, cut holes 12 and auxiliary holes 13 below the waistline.

[0118] Refer to Figure 2 , the peripheral holes 14 located on the contour of the arch top P2 are deflected upward by 2°, the peripheral holes 14 located on the side wall P3 contour are deflected to the left or right by 2°, and the peripheral holes 14 located on the floor P4 contour are deflected downward by 3°. The empty holes 11, cut holes 12, and auxiliary holes 13 are all 90° vertical holes.

[0119] The initiation method of the blast holes adopts bottom initiation with digital detonators. Two detonators are arranged in the cut holes 12, and single detonators are arranged in the remaining drilling blast holes.

[0120] The delay initiation sequence is: first initiate the cut holes 12, then initiate the auxiliary holes 13 and the peripheral holes 14 below the roadway waistline, and finally initiate the peripheral holes 14 above the roadway waistline.

[0121] As Figure 3 shown, immediately after blasting, the roadway ventilation is carried out. After the ventilation is completed, the mucking operation is carried out, and the loose muck fallen by blasting is cleared to the roadway waistline P1 area. A special concrete layer 2 is made on the surface of the arch top P2. The special concrete layer 2 is formed by spraying special concrete with a dry shotcrete machine, the spraying thickness is 15 cm, and the strength of the special concrete layer 2 is not less than 10 MPa after spraying for two hours.

[0122] As Figure 4 shown, 2 hours after the production of the special concrete layer 2, 3 cable anchor holes 38 are drilled on the surface of the arch top P2, and deep anchor point prestressed cable anchors 3 are installed in the cable anchor holes 38.

[0123] The diameter of the cable anchor hole 38 is 65 mm and the depth is 6 m; the steel strand 31 of the deep anchor prestressed cable 3 has a diameter of 21.8 mm, a length of 6.6 m, and the locking force is not less than 300 kN.

[0124] The unit anchor 35 on the deep anchor prestressed cable 3 is a circular extrusion steel body, made of 45# steel, with an outer diameter of 50 mm and a length of 100 mm.

[0125] The size of the tray 33 of the deep anchor prestressed cable 3 is 250 mm * 250 mm, and the thickness is 16 mm.

[0126] The grouting pressure is 6 - 20 MPa, and the water-cement ratio of the slurry is 0.45:1 - 0.50:1.

[0127] As Figure 5 and Figure 6 shown, with the help of the deep anchor prestressed cable 3, the wire mesh 4 and the steel strip 5 are pre-hung. The diameter of the steel bars in the wire mesh 4 is 6 mm, and the mesh size is 100 mm × 100 mm. The steel strip 5 is a W-shaped steel strip, with a width of 200 mm, a thickness of 3 mm, and a hole diameter of 25 mm.

[0128] As Figure 4 shown, after the wire mesh 4 and the steel strip 5 are hung, anchor bolt holes are drilled on the surface of the roof P2 and the two side walls P3 of the drift, and the system anchor bolts 6 are installed in the anchor bolt holes. The diameter of the anchor bolt holes is 30 mm and the depth is 2 m; the diameter of the system anchor bolts 6 is 20 mm, the length is 2.2 m, and the locking force is not less than 60 kN.

[0129] As Figure 8 shown, the deep anchor prestressed cable 3 and the system anchor bolts 6 are arranged in the same row, and multiple rows of deep anchor prestressed cables 3 and system anchor bolts 6 are arranged, with a row spacing of 1.2 m.

[0130] The thickness of the ordinary concrete sprayed in the full section is 10 cm, and the grade of the ordinary concrete is C20 or above.

[0131] In this application, low-disturbance controlled blasting is carried out by controlling the depth of the rock drilling holes, optimizing the hole layout, adjusting the charge amount and the detonation sequence, so that the blasting energy is released orderly, reducing the disturbance of the blasting energy to the surrounding rock of the roof of the stope drift, reducing the risk of roof collapse, and effectively ensuring the safety of the staff.

[0132] After the blasting mucking is completed, this application also forms a special ultra-early-strength concrete by mixing the cement slurry containing various additives with the water body containing a quick-setting agent, and sprays the special concrete onto the surface of the roof of the drift to form a special concrete layer 2, which can quickly form a high-strength support layer on the roof surface, shorten the exposure time of the roof, and timely inhibit the initial deformation of the surrounding rock of the roof.

[0133] This application uses deep anchor prestressed anchor cables 3 and systematic bolts 6 for support, deeply stabilizing the broken surrounding rock of the roadway arch top P2, and cooperating with steel mesh 4 and steel strips 5 for full-section systematic support to form a multi-level support system, significantly enhancing the overall stability of the surrounding rock, greatly reducing the deformation of the surrounding rock, effectively reducing the necessity and cost of secondary support, and effectively ensuring the long-term stability of the roadway.

[0134] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0135] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A stope heading excavation and support method, characterized in that Including: Drill rock drilling blast holes at the driving face of the stope heading, and use short-hole blasting. The rock drilling blast holes include multiple cut holes, multiple auxiliary holes and multiple perimeter holes. Among them, multiple said cut holes are arranged around the center of the driving face, multiple said auxiliary holes are arranged around the periphery of the multiple cut holes, and multiple said perimeter holes are arranged along the contour of the driving face. The charge amount of the rock drilling blast holes above the waistline of the heading is lower than that of the rock drilling blast holes below the waistline of the heading; first detonate the cut holes, then detonate the auxiliary holes and the perimeter holes below the waistline of the heading, and finally detonate the perimeter holes above the waistline of the heading; After blasting, clear the blasted loose slag to the waistline part of the heading, and then carry out pre-support operation on the crown of the stope heading; After the pre-support operation is completed, remove all the remaining loose slag that has fallen, and then carry out systematic support operation on the full section of the stope heading.

2. The stope drift excavation and support method according to claim 1, wherein, The depth of the rock drilling blast holes is 0.8 m to 1.5 m; and / or, the charge amount of the rock drilling blast holes above the waistline of the heading is 1 / 2 to 2 / 3 of the charge amount of the rock drilling blast holes below the waistline of the heading.

3. The stope heading and support method according to claim 1, characterized in that The auxiliary holes are arranged below the crown of the driving face; and / or, the hole spacing of the perimeter holes at the crown of the driving face is smaller than the hole spacing of the perimeter holes on the side wall of the driving face, and the hole spacing of the perimeter holes at the crown of the driving face is also smaller than the hole spacing of the perimeter holes at the floor of the driving face.

4. The stope drift excavation and support method according to claim 1, characterized in that, Drill a relief hole at the center position of the multiple cut holes; and / or, the hole angle of the perimeter holes deflects outward by 1° to 3°.

5. The stope drift excavation and support method according to claim 1, characterized in that Carrying out pre-support operation on the crown of the stope heading includes: Spray special concrete with a thickness of 10 cm to 15 cm on the surface of the crown of the stope heading to form a special concrete layer for pre-support on the crown surface.

6. The stope drift excavation and support method according to claim 5, characterized in that, The special concrete is made of crushed stone, sand, water, accelerator and cementitious material, and the special concrete is sprayed on the surface of the crown of the stope heading by using a dry shotcreting machine to form the special concrete layer.

7. The stope drift excavation and support method according to any one of claims 1 to 6, characterized in that, Carrying out systematic support operation on the full section of the stope heading includes: Drill cable holes from the center of the surface of the crown of the stope heading into the deep ore body, and drill cable holes from the surface of the shoulder angle part of the crown of the stope heading into the deep ore body, and install deep anchor point prestressed cables in the cable holes; Hang a wire mesh and a steel strip by means of the deep anchor point prestressed cables; Drill bolt holes on the surface of the crown and the two side walls of the stope heading, and install systematic bolts in the bolt holes; Spray ordinary concrete with a thickness of 5 cm to 10 cm on the full section.

8. The stope drift excavation and support method according to claim 7, characterized in that, Installing deep anchor point prestressed cables in the cable holes includes: Place the anchoring agent at the bottom of the cable hole; Use the cable drill to drive the deep anchor point prestressed cable to rotate and advance in the cable hole, and the deep anchor point prestressed cable stirs the anchoring agent to make it solidify; After solidification, tension the deep anchor point prestressed cable to make the deep anchor point prestressed cable tensioned to the preset locking force value; Inject cement slurry into the cable hole to form a cement slurry stone body.

9. The stope drift excavation and support method according to claim 7, characterized in that, The deep anchor point prestressed cable includes steel strand, locking device, tray, unit anchor point, isolation pipe and anchoring agent; Among them, after the anchoring agent is cured, it is fixed at the bottom of the cable bolt hole. The steel strand is threaded through the cable bolt hole, and one end of the steel strand is fixedly connected to the cured anchoring agent, and the other end is exposed outside the cable bolt hole. Unit anchor points are arranged on the steel strand, and the unit anchor points are close to the anchoring agent. The locking device and the tray are installed at the orifice of the cable bolt hole to tension and lock the steel strand. The isolation pipe is wrapped on the outer surface of the steel strand except for the unit anchor points.

10. The stope drift excavation and support method according to claim 7, wherein The depth of the cable bolt hole is 5 m to 8 m, and no less than 80% of the hole depth of the cable bolt holes at the shoulder angle of the arch roof is located in the ore body on the side away from the drift on the upward extension line of the side wall of the drift. The depth of the bolt hole is 2 m to 3 m. The number of systematic bolts arranged at the arch roof is no less than 4, and the number of systematic bolts arranged corresponding to each side wall is no less than 2. The deep anchor point prestressed cable bolts are arranged in the same row as the systematic bolts, and multiple rows are arranged along the heading direction of the drift. The row spacing is not greater than the depth of the heading cycle footage of the drift.

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