Mining and supporting method for downward inverted trapezoidal long drift of steeply inclined thin vein

Abstract

The invention discloses a method for mining and supporting a downward inverted trapezoidal long drift of a steeply inclined thin vein, and belongs to the technical field of mine engineering. A horizontally arranged main connection way is used as a shared connection way of other layers in a section, so that an opening area of the connection way of the next layer is located in the connection way of the previous layer, and meanwhile, the opening position is controlled; projections of all the openings on the main connection way are not overlapped, and projections of all the layered connection ways in the vertical direction are not completely overlapped. For the non-adjacent stopes, the opening of the connection way is arranged in the adjacent layered connection way closest to the main connection way, so that the repeated tunneling workload is reduced through roadway sharing, the engineering construction cost is directly reduced, and the construction period is directly shortened; meanwhile, by means of the design that the staggered openings and the vertical projection are not completely overlapped, the situation that all the layered connection ways form continuous empty areas in the vertical direction is avoided, surrounding rock stress is dispersed, and the problem that in the prior art, surrounding rock is broken due to stress superposition is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine engineering, and particularly relates to a method for downward inverted trapezoidal long drift mining and support of steeply inclined thin ore veins. BACKGROUND

[0002] In the process of mining steeply inclined thin ore veins, as the mining advances to the deep part, the development degree of joint fissures of ore rock rises sharply, and the original upward drift mining method is difficult to apply, and the mining method needs to be converted. In this process, in view of the characteristics of the steeply inclined thin ore veins with many sub-layers, the traditional technology adopts a mode of independent tunneling of sub-layers, that is, a complete sub-lay mining field is independently tunneled to be connected with the transportation roadway. This mode not only produces a large amount of roadway tunneling engineering, resulting in an increase in labor, material and time costs, but also forms a continuous roadway empty area, causing stress superposition effect of surrounding rock. Especially in the working condition where the traditional upward mining is converted into downward mining due to the influence of the ore body fracture zone, the stability of the surrounding rock in the stress superposition area is further reduced, and geological disasters such as roadway deformation, surrounding rock crushing and even collapse are prone to occur, which seriously restricts the continuity and safety of mining operations. SUMMARY

[0003] In view of the technical problems in the background art, the application provides a method for downward inverted trapezoidal long drift mining and support of steeply inclined thin ore veins, which comprises the following steps: S1. A mining conversion process is designed, the thickness of the isolation pillar of the upward horizontal sub-layer filling mining method converted into the downward drift method is calculated comprehensively, and an isolation pillar is arranged between the area mined by the original upward drift method and the area mined by the present downward inverted trapezoidal long drift mining method; S2. A mining field and a middle section transportation roadway are arranged; S3. A draw shaft is arranged from the existing vein roadway of the mine, a plurality of sub-layer mining fields are arranged as one section, and a horizontal main trunk mining field connecting passage is constructed from the section transportation roadway to the mining field at the same level in the section; S4. A slanting sub-layer mining field connecting passage is constructed from the main trunk mining field connecting passage to the adjacent mining field in the same section, a common mining field connecting passage is used, the opening area of the next sub-layer mining field connecting passage is located in the sub-layer mining field connecting passage, the projection of each opening in the main trunk mining field connecting passage does not overlap, and the projection of each sub-layer mining field connecting passage in the vertical direction does not completely overlap; S5. Rock drilling and blasting are carried out from the middle part of the mining field to the two sides to carry out the first mining layer operation; S6. The first mining layer is supported, the roof and the lower disc side slope use anchor rods, and the upper disc side slope uses anchor rods and mortar anchor rods; S7. The first mining layer is filled; S8. The remaining sub-layers are mined; S9. The remaining sub-layers are supported and filled, and mortar anchor rods are arranged at the lower disc near the floor to pre-support the roof of the lower sub-layer.

[0004] In some embodiments, in step S3, the projections of the openings of the drifts connecting the stopes and the drifts in the same subzone do not coincide in the vertical direction.

[0005] In some embodiments, in step S3, among the drifts connecting the stopes and the drifts in the same subzone, the openings of the main trunk drifts connecting the stopes are preferentially arranged in the central part of the stopes.

[0006] In some embodiments, in step S3, among the drifts connecting the stopes and the drifts in the same subzone, when the opening of one of the drifts is arranged in the central part of the stope, the projection of the opening of the drift in the adjacent layer is adjacent to the central part of the stope and does not coincide with the opening arranged in the central part of the stope.

[0007] In some embodiments, the projections of the openings of the drifts connecting the stopes and the drifts in the same subzone do not coincide.

[0008] In some embodiments, in step S1, the method further comprises arranging steel bars in the middle section of the upper part of the broken zone which is not mined and improving the strength of the first mining layer and the second layer of the filling body.

[0009] In some embodiments, in step S2, the cross section of the stope is inverted trapezoidal.

[0010] In some embodiments, in steps S6 and S9, the anchor rods of the upper disc of the inverted trapezoidal stope cross section are arranged in a dense manner.

[0011] In some embodiments, in steps S6 and S9, the anchor rods of adjacent layers are arranged in a staggered manner.

[0012] In some embodiments, the method further comprises: S10, alternating the work in the multiple stopes through the drifts.

[0013] By arranging the main trunk drifts horizontally as the common drifts of other layers in the same section, the opening area of the next layer drift is located inside the previous layer drift, and the opening position is controlled to ensure that the projections of the openings on the main trunk drift do not overlap, and the projections of the drifts in the vertical direction do not completely overlap. For non-adjacent stopes, the drift openings are arranged in the layer drift closest to the main trunk drift, thereby reducing the repeated excavation work through roadway sharing, directly reducing the engineering construction cost and construction period; at the same time, the staggered opening and the design of the vertical projection not completely overlapping avoid the formation of continuous empty area in the vertical direction of each layer drift, disperse the stress of the surrounding rock, and solve the problem of broken surrounding rock caused by stress superposition in the traditional technology; thirdly, the non-overlapping opening position can also ensure that the turning point of the ore transport vehicle does not coincide, thereby ensuring the smoothness of ore transfer. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a whole stope layout mode schematic diagram of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 2 is a layout schematic diagram of an opening area between a crossway and a stope of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 3 is a layout mode schematic diagram of a stope crossway of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 4 is a schematic diagram of another angle of a layout mode of a stope crossway of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 5 is a schematic diagram of a filling and supporting method of an inverted trapezoidal stope of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 6 is a schematic diagram of arrangement of each anchor rod and steel mesh in a first mining layer in a filling and supporting method of an inverted trapezoidal stope of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application; Figure 7 is a schematic diagram of arrangement of each anchor rod and steel mesh in other layers in a filling and supporting method of an inverted trapezoidal stope of a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method provided by an embodiment of the present application.

[0015] Reference signs: 1, middle section transportation roadway; 2, subsection transportation roadway; 31, first layer stope; 32, second layer stope; 33, third layer stope; 34, fourth layer stope; 41, main stope crossway; 42, first layer stope crossway; 43, third layer stope crossway; 44, fourth layer stope crossway; 5, isolated ore pillar; 6, inverted trapezoidal stope; 7, filling body; 8, chute; 9, low strength filling body; 10, high strength filling body; 11, pipe slot anchor rod; 12, surrounding rock; 13, grouting anchor rod; 14, hanging bar; 15, gravel layer; 16, longitudinal bar; 17, transverse bar; 18, anchor net; 19, double bar. DETAILED DESCRIPTION

[0016] The embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical scheme of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0017] 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 belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise noted, the terms "including" and "comprising" are open-ended and do not exclude the presence of unrecited elements or limitations.

[0018] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0019] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, nor is it necessarily a separate or alternative embodiment to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with each other.

[0020] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0021] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0022] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and are not intended to indicate or imply that the indicated devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0023] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mount", "connect", "connect", "fix", and other terms should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0024] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0025] In some embodiments, with reference to Figures 1 to 7 A steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method, comprising: S1, carry out the process design of turning mining, comprehensively calculate the thickness of the isolation pillar of turning the upward horizontal slicing and filling mining method into the downward drift method, and leave the isolation pillar between the area mined by the original upward drift method and the area mined by the present downward inverted trapezoidal long drift mining method; specifically, this step is to carry out the process design of turning the upward horizontal slicing and filling mining method into the downward inverted trapezoidal long drift method, through geomechanical calculation, numerical simulation analysis and other means, comprehensively considering parameters such as ore body occurrence conditions, to determine the reasonable thickness of the isolation pillar; a continuous isolation pillar is left between the area left by the original upward drift mining and the present downward mining area according to the calculated thickness, to ensure that the pillar is complete without fracture. The filling body in the area mined by the original upward method may have strength decay due to long-term stress, and there is stress concentration phenomenon at the boundary of the original mined-out area; when mining by the downward method, the drift excavation will change the distribution of the surrounding stress field, and if there is no isolation structure, it is easy to cause the original filling body to lose stability and collapse, thereby affecting the safety of the present downward mining operation. The specific parameters of the isolation pillar are calculated in combination with the specific mine geological conditions, so as to build a stress isolation barrier between the original mined-out area and the present mining area, and block the stress transmission and risk diffusion between the original mined-out area and the present mining area.

[0026] For example, with reference to Figure 1 Taking the isolation pillar 5 as the core boundary, the parameters of the two side areas are collected, the specific geomechanical parameters of the mine are collected, for the filling body 7 in the area left by the original upward drift mining above the isolation pillar 5, the strength decay data of the original filling body in the area are measured, and the stress concentration distribution of the original mined-out area is measured, and the stress superposition parts near the middle section transport roadway 1 and the sectional transport roadway 2 are focused on as the core basis for calculation.

[0027] With reference to Figure 1 and Figure 2For the current downward trapezoidal long-entry mining area below the isolation pillar 5, the strength of the ore and rock and the degree of joint and fracture development of the first layer stope 31, the second layer stope 32, the third layer stope 33 and the fourth layer stope 34 were collected. At the same time, the occurrence pattern and dip angle change of the ore body along the strike of the middle section transport roadway 1 were recorded.

[0028] Based on the preset position of isolation pillar 5, and combining various theoretical methods such as the KB Rubeneit formula, thickness-to-span ratio method, load transfer intersection method, and material mechanics method, along with geomechanical calculations and numerical simulation analysis, the reasonable thickness of the isolation pillar is comprehensively calculated to ensure that stress transfer between the original goaf and the current mining area can be blocked.

[0029] Between the original upward-facing mining area and the current downward-facing trapezoidal long-cut mining area, continuous, intact, and unbroken isolation pillars are strictly constructed according to the calculated thickness to create a stress isolation barrier and prevent the stress field changes caused by the downward-facing tunneling from causing the original filling material to become unstable and collapse.

[0030] S2, Arrange the mining area and intermediate transport roadway; for example, refer to... Figure 1 and Figure 2 ,by Figure 1 Taking the currently mined area to the right of the central isolation pillar 5 as the core, and combining the strike, dip angle, and thickness variations of the ore body, independent stopes are divided: According to the length of the mining area Figure 1 The continuous occurrence section of the ore body is determined to ensure that each stope corresponds to a complete and unbroken ore body, forming a vertically stacked layout of the first-layer stope 31, the second-layer stope 32, the third-layer stope 33, and the fourth-layer stope 34, with each stope being independently separated and having clear boundaries. The width of the stope is directly matched to the actual thickness of the ore body, ensuring that the stope cross-section can fully accommodate the mining area of ​​the ore body, while also... Figure 2 The openings of the connecting passages between the various mining areas are adapted to meet the requirements, so as to avoid the mining areas being too wide or too narrow, which would affect subsequent drilling and ore extraction operations. Avoid when dividing Figure 1 The vertical passage of the ore pass 8 ensures that the spatial distance between each stope and the ore pass 8 meets the requirements for ore transfer efficiency, and maintains continuous connection with the right boundary of the isolation pillar 5 without compromising the integrity of the stress isolation barrier.

[0031] The orientation of the intermediate transport roadway 1 is consistent with the orientation of the ore body. It is adjacent to the area below the isolation pillar 5 on the left and connects to the sub-transport roadway 2 and the main mining area connecting roadway 41 via the ore pass 8 on the right.

[0032] S3, set a slope shaft from the existing vein roadway in the mine, set multiple sublevel stopes as one section, and connect the main stope in the stope from the section transportation roadway to the stope at the same level as the main stope in the section; specifically, the main stope connecting tunnel is arranged horizontally, because in the subsequent transportation process, the main stope connecting tunnel serves as a ore gathering channel for the sublevel stopes, and will bear the main ore transfer work, and the main stope connecting tunnel is arranged horizontally, which can avoid the safety risk of equipment operation in the inclined roadway.

[0033] S4, from the main stope connecting tunnel opening, make a inclined sublevel stope connecting tunnel in the adjacent stope in the same section, share the main stope connecting tunnel, and make the next sublevel stope connecting tunnel opening area in the upper sublevel stope connecting tunnel, and the projection of each opening in the main stope connecting tunnel does not overlap, and the projection of each sublevel stope connecting tunnel in the vertical direction does not completely overlap; Specifically, the steeply inclined thin vein has many sublevels, and if a complete connecting tunnel is excavated for each sublevel, it will result in large amount of roadway engineering and high cost, and is prone to form a stress superposition area in the vertical direction. In the current working condition where the upward mining is changed to downward mining due to the problem of the fracture zone, the influence of the stress superposition area is more obvious. Through the design of shared roadway combined with staggered openings, the amount of excavation work can be reduced, and the continuous empty area of each sublevel connecting tunnel in the vertical direction can be avoided, so as to disperse the stress of the surrounding rock and prevent the surrounding rock from being broken due to multiple excavations in a single area. In addition, the engineering cost is reduced, the layout of the roadway space is optimized, and the stress concentration risk of the surrounding rock is dispersed.

[0034] For example, referring to Figure 1 and Figure 3 , the section transportation roadway 2 is arranged at a horizontal position flush with the second sublevel stope 32, so as to ensure that there is no height difference in the vertical direction; the main stope connecting tunnel 41 is constructed horizontally between the section transportation roadway 2 and the second sublevel stope 32 with a cross-sectional size of 3m x 3m, which serves as the opening mother tunnel of all sublevel stope connecting tunnels, and ensures that the axial direction matches the ore body trend and the sublevel stope layout, thereby providing a stable starting point for the opening of each sublevel connecting tunnel.

[0035] Referring to Figure 3 and Figure 4 , in combination with the maximum driving slope requirement of the mining equipment, the first opening point is selected in the left area of the main stope connecting tunnel 41 shown in Figure 3 ; the excavation trolley is used to excavate upward along the inclined direction by using the straight-hole slotting blasting process until it penetrates the first sublevel stope 31 marked in Figure 1 , Figure 3 , thereby forming the first sublevel stope connecting tunnel 42.

[0036] On the main stope connecting tunnel 41, a new opening point that does not overlap with the first sublevel opening point is selected; the straight-hole slotting blasting process is used to excavate downward along the inclined direction until it penetrates the second sublevel stope 32 marked inFigure 1 , Figure 3 The third-level stope 33 was completed, forming the third-level stope connecting passage 43. After excavation, the vertical projection of the third-level stope connecting passage 43 was checked to ensure that it did not completely overlap with the vertical projection of the first-level stope connecting passage 42, thus avoiding the formation of continuous voids in the vertical direction that could lead to stress superposition.

[0037] Reference Figure 3 and Figure 4 The fourth-level mining area 34, which is not directly adjacent to the main mining area connecting road 41, shall, in accordance with the principle of relying on the nearest excavated connecting road, be located in... Figure 3 , Figure 4 An opening area is set up inside the third-level stope connecting roadway 43, near the main stope connecting roadway 41; the same straight-hole cut-and-blast process is used to excavate downwards at an angle until it connects with the fourth-level stope 34, forming the fourth-level stope connecting roadway 44. By sharing the third-level stope connecting roadway 43, the excessively steep inclination of the fourth-level stope 34 to the main stope connecting roadway 41 is avoided, thus completing the final connection. Figure 3 The connecting tunnels between the first to fourth mining areas in this section are now fully connected.

[0038] S5. Drilling and blasting are carried out from the middle of the mining area to both sides to start the first mining layer operation; For example, starting from the middle of the stope, drilling and blasting operations are gradually advanced to both sides of the stope. A YT-28 pneumatic rock drill is used for drilling operations, with blast holes arranged horizontally, the diameter of the blast holes controlled between φ32 and 38 mm, and the depth of a single hole set at 2.5 m.

[0039] The design of the borehole layout for straight-hole slotting and smooth blasting is then carried out using a segmented charging structure, with No. 2 rock emulsion explosive selected. After all the boreholes on the working face have been drilled, the charging operation is carried out uniformly.

[0040] Digital electronic detonators are used for initiation. After a single blast, the working face is moved to both sides of the mining area, and the above process is repeated until all drilling and blasting operations of the first mining layer are completed.

[0041] S6. For the first mining layer, anchor bolts are used for the roof and lower sidewalls, while a mixture of anchor bolts and mortar anchor bolts is used for the upper sidewalls; for example, refer to Figures 5 to 7 Select pipe joint anchor rods 11 with a diameter of 42mm and a length of 2.0m, and lay them at a spacing of 1.0~1.2m and a row spacing of 1.2m. Simultaneously lay anchor mesh 18 and double reinforcing strips 19 to ensure that the ends of the anchor rods are firmly fixed to the anchor mesh and double reinforcing strips. The roof is selected with a pipe and slot anchor rod 11 with a diameter of 42 mm and a length of 2.0 m, arranged at a spacing of 1.2 m and a row spacing of 1.2 m, matched with an anchor net 18 and a double steel bar 19, and the anchor rod direction is perpendicular to the surface of the surrounding rock 12 of the lower disc, so as to avoid reducing the supporting force due to angle deviation; The pipe and slot anchor rod 11 and the grouting anchor rod 13 are mixed and used at a spacing of 1.2 m and a row spacing of 1.2 m, the pressure is controlled at 0.3-0.5 MPa and the time is controlled at 25-30 minutes during grouting, so as to ensure that the slurry penetrates into the fissures of the surrounding rock 12 of the upper disc.

[0042] S7, filling the first mining layer; For example, referring to Figures 5 to 7 After the support of the first mining layer is completed, the floor of the mining field is cleaned first, a 10-20 cm thick gravel layer 15 is laid on the floor and the surface is leveled, then a floor steel mesh is laid according to a 250 mm x 500 mm grid, wherein the longitudinal steel bars 16 have a diameter of φ10-12 mm and a spacing of 500 mm, the transverse steel bars 17 have a diameter of φ6 mm and a mesh of 500 mm x 500 mm, and the hanging steel bars 14 with a diameter of φ10-12 mm are hung, the row spacing of the hanging steel bars 14 is 0.5 m and there are 4 hanging steel bars in each row, which are used to fix the steel mesh and the subsequent filling body.

[0043] A filling retaining wall is built at the boundary of the mining field, a filter pipe is buried in the inside of the retaining wall, and then filling material slurry is injected into the mining field, and the layered strength of the filling body is controlled according to Figure 5 As shown, the lower part 1.5-2.0 m is a high-strength filling body 10 (the strength after 28 days is not less than 4.0 MPa), and the upper part 1.5-2.0 m is a low-strength filling body 9.

[0044] After filling, maintenance is carried out for more than 7 days, during which the filling wastewater is monitored to flow through the filter pipe into the roadway ditch and finally into the middle section water sump, and after the maintenance is qualified, it is confirmed that Figure 5 The filling body (including 9 and 10) is closely attached to the surrounding rock 12 without cavities or fissures.

[0045] S8, carrying out the rest of the layered mining operation; For example, the rest of the layered mining operation still advances from the middle of the mining field to both sides for rock drilling, blasting and ore mining, the rock drilling and blasting adopt a non-cutting smooth blasting process, one slotted hole with a depth of 20 cm deeper than other blast holes is drilled in the middle of the working face and on both sides of the weak structural plane, auxiliary holes are arranged at a spacing of 0.4-0.8 m, the peripheral hole is 10 cm away from the boundary of the mining field as a retaining wall, the diameter of the blast hole is controlled at φ32-38 mm and the hole depth is 2.5 m, after all the blast holes in the working face are drilled, 2# rock emulsion explosive cartridges and sectional detonating cord detonators are loaded into the holes, an electronic detonator is used to initiate the explosion outside the hole, after blasting, ventilation and cleaning of the ore slag are carried out, and a shovel is used to mine, and the vertical and horizontal distances between the adjacent layered communication ways are both not less than 5 m to avoid mutual interference of the operations.

[0046] S9, filling and supporting the rest of the layer, setting the mortar anchor rod pre-supporting the lower layer roof near the floor at the upper disc.

[0047] For example, with reference to Figure 7 The pipe and slot anchor rod 11 is selected for the first mining layer, but the grouting anchor rod 13 does not need to be additionally arranged.

[0048] The application provides a steeply inclined thin vein downward inverted trapezoidal long drift mining and supporting method, comprising the following steps: S1, a conversion mining process design is performed, and the thickness of the isolation pillar of the upward horizontal layer filling mining method converted into the downward drift method is comprehensively calculated, and an isolation pillar is arranged between the area after the original upward drift method mining and the area mined by the present downward inverted trapezoidal long drift mining method; S2, a stope and a middle section transportation roadway are arranged; S3, a draw shaft is arranged from the existing vein roadway of the mine, a plurality of layer stopes are arranged as a section, and a main trunk stope connecting way is constructed from the section transportation roadway to the stopes in the same horizontal plane in the section; S4, a slanting layer stope connecting way shared part stope connecting way is formed from the main trunk stope connecting way opening to the adjacent stopes in the same section, the opening area of the next layer stope connecting way is located in the upper layer stope connecting way, the projection of each opening on the main trunk stope connecting way is not overlapped, and the projection of each layer stope connecting way in the vertical direction is not completely overlapped; S5, rock drilling and blasting are carried out from the middle part of the stope to the two sides to carry out the first mining layer operation; S6, the first mining layer is supported, the roof and the lower disc side slope are supported by anchor rods, and the upper disc side slope is supported by anchor rods and mortar anchor rods; S7, the first mining layer is filled; S8, the rest of the layer stoping operation is carried out; S9, the rest of the layer is filled and supported, and the mortar anchor rod pre-supporting the lower layer roof near the floor at the upper disc is arranged.

[0049] The main trunk connecting way arranged horizontally is used as the shared connecting way of other layers in the section, the opening area of the next layer connecting way is located in the previous layer connecting way, the opening position is controlled, the projection of each opening on the main trunk connecting way is not overlapped, and the projection of each layer connecting way in the vertical direction is not completely overlapped. For non-adjacent stopes, the connecting way opening is arranged in the layer connecting way closest to the main trunk connecting way, thereby reducing the repeated excavation work amount through roadway sharing, directly reducing the engineering construction cost and construction period; meanwhile, the staggered opening and the design of the vertical projection not completely overlapped avoid the formation of continuous empty areas in the vertical direction of each layer connecting way, disperse the surrounding rock stress, and solve the problem of broken surrounding rock caused by stress superposition in the traditional technology; thirdly, the non-overlapping opening position can also ensure that the turning point of the ore transportation vehicle is not overlapped, thereby ensuring the smoothness of ore transportation.

[0050] In some embodiments, referring to Figure 2 In step S3, the projections of the openings of the stope connecting passages of the adjacent layers in the same subzone in the vertical direction do not coincide. Specifically, the surrounding rock of the steeply inclined thin vein itself has weak bearing capacity, and is affected by the weight of the ore body and mining disturbance, and the stress field distribution is complex. If the vertical projections of the openings of the adjacent layers coincide, a vertically penetrating roadway cluster will be formed in this area. The surrounding rock of the upper layer opening has undergone a certain degree of plastic deformation and stress release after mining. When the lower layer is excavated at the same projection position, the surrounding rock in this area will bear the superimposed stress of multi-layer mining, and the stress concentration coefficient will greatly increase, which will easily cause the surrounding rock to break, peel or collapse when the stress exceeds the compressive strength of the surrounding rock.

[0051] The non-coincidence design of the projections can stagger the stress fields of the adjacent layers, disperse the stress of the surrounding rock to different areas, and share the load by using the cooperative bearing capacity of the surrounding rock, thereby avoiding the failure of a single area due to stress concentration.

[0052] In some embodiments, referring to Figure 2 In step S3, in the stope connecting passages of the adjacent layers in the same subzone, the opening between the main trunk stope connecting passage and the stope is preferentially arranged at the central part of the stope.

[0053] Specifically, the space of the stope of the steeply inclined thin vein is narrow, and the operations such as ore transportation and rock drilling and blasting are significantly constrained by space. The central opening can maximize the adaptation to the operation demand. During the stoping, the operation advances symmetrically from the central opening to both sides, the distance between the operation surface of the rock drilling and blasting and the opening is equal, which avoids the problem of too long transportation distance of the remote operation surface caused by unilateral advancement. The ore can be quickly collected from both sides to the central opening, and then transported to the ore pass through the main trunk connecting passage, thereby reducing the accumulation and secondary transportation of the ore in the stope.

[0054] In some embodiments, referring to Figure 2 In step S3, in the stope connecting passages of the adjacent layers in the same subzone, when the opening of one of the stope connecting passages is arranged at the central part of the stope, the projection of the opening of the stope connecting passage of the adjacent layer is adjacent to the central part of the stope and does not coincide with the opening arranged at the central part of the stope.

[0055] Specifically, if the vertical projections of the openings of the adjacent layers coincide with the central opening, a multi-layer penetrating stress concentration zone will be formed in this area. The surrounding rock or filling body of the upper layer opening bears the mining disturbance, which causes stress superposition when the lower layer is excavated at the same projection position, and easily leads to the breakage of the surrounding rock or the cracking of the filling body. The non-coincidence design can stagger the stress peak areas of the adjacent layers, and disperse the load by using the cooperative bearing capacity of the surrounding rock and the filling body.

[0056] On this basis, the projection of the openings of the drifts of the stopes of the adjacent layers is adjacent to the central part of the stope, which can avoid the situation that the ore body transportation distance of one end is too long due to the deviation of the opening from the central part, and ensures the efficiency of ore recovery.

[0057] In some embodiments, with reference to Figure 2 , the projections between the openings of the drifts of the stopes of the adjacent layers are also not coincident.

[0058] Specifically, the projections between the openings of the drifts of the stopes of the adjacent layers refer to the adjacent combination of the stope drifts and the stope connection openings of all adjacent layers in the same section, i.e. the adjacent combination of the central opening and the non-central opening, the non-central opening and the non-central opening, which have no overlap in the vertical direction. Through the spatial dislocation of all layer openings, it is avoided to form any form of continuous through-type empty area or continuous stress concentration zone in the vertical direction, so as to block the multi-layer stress accumulation and continuous failure of the filling body, and ensure the overall stability of the surrounding rock and the support system of the whole section.

[0059] In some embodiments, with reference to Figure 1 In step S1, the first layer of steel bars is laid on the upper unsampled middle section of the broken zone, and the strength of the first mining layer and the second layer of filling body is improved.

[0060] Specifically, the core risk of the broken zone of the steeply inclined thin ore vein is that the upper unsampled middle section cannot withstand the shear force along the ore body and the suspended roof load in the vertical direction due to the dip angle, and the compressive strength of the broken surrounding rock often cannot withstand this load. Therefore, a high-strength filling body is first used to form a reinforced bearing system to directly bear the core load and avoid local crushing, and then a steel mesh is used to limit the expansion of micro-cracks in the filling body to improve the crack resistance of the filling body.

[0061] In some embodiments, with reference to Figure 1 In step S2, the stope section is inverted trapezoidal. Specifically, the ore body trend, dip angle and thickness are determined through geological exploration, the stope boundary is calibrated in the middle section transportation roadway or the section transportation roadway, and the bottom edge, top edge and height parameters of the inverted trapezoidal section are determined. An excavation trolley is used to excavate from the main trunk stope drift to the inside of the stope, blast holes are arranged according to the design section parameters, straight-hole slotting smooth blasting technology is used to control the shaping of the side slope, and the peripheral hole charge quantity is strictly controlled during blasting to avoid overbreak or underbreak. After blasting, the stope floatstone is ventilated and cleaned, a laser section instrument is used to detect the section shape, and the areas with a side slope that does not meet the design requirements of 5-8° inclination angle are subjected to secondary trimming, so as to finally form an inverted trapezoidal stope section with a width of 3-4m, a length of 80-100m and a height of 3-4m, and the inclination angle of the two side slopes meets the design requirements, so as to ensure that the section can accommodate the normal operation of the shovel-truck and anchor rod machine and other equipment.

[0062] The inverted trapezoidal structure with the upper part wider and the lower part narrower can disperse the vertical pressure of the upper disc surrounding rock to the upper part of the stope filling body, avoiding the occurrence of slices due to stress concentration on the side slope; in addition, the inverted trapezoidal structure can adapt to the characteristics of the steeply inclined ore body, reduce the exposed area of the surrounding rock, and reduce the risk of roof collapse.

[0063] In some embodiments, in steps S6 and S9, the anchor rods of the upper disc of the inverted trapezoidal stope section are arranged in a high-density manner.

[0064] Specifically, the vertical pressure and the shear force along the inclination of the surrounding rock of the upper disc of the inclined ore body will act on the side slope of the upper disc first, and the thickness of the surrounding rock of the side slope of the upper disc of the thin ore vein is small, and the joint fissure is developed, so that the conventional density anchor rod is difficult to resist concentrated stress and is prone to slice accidents; by increasing the density of the anchor rod, the integrity of the surrounding rock of the upper disc can be enhanced, the local concentrated stress can be dispersed to more anchor rods, the shear resistance and the spalling resistance of the side slope can be improved, and slice accidents can be avoided.

[0065] Specifically, in the inverted trapezoidal stope section, after blasting and forming and cleaning the floatstone, the anchor rod density parameters are determined according to the inclination angle of the upper disc side slope and the joint development of the surrounding rock; a YT-28 air leg rock drill or an anchor rod machine is used to drill a hole vertically along the inclined surface of the upper disc side slope; after the drilling is completed, the debris in the mortar anchor rod hole is cleaned first, M30 cement mortar is injected, and then the tubular slotted anchor rod and the mortar anchor rod are installed synchronously; after the installation is completed, the anchor rod anchoring force is checked by using a torque wrench, and whether the spacing between the anchor rods meets the density requirements is checked, so that a uniform anchor rod support structure with a higher density on the upper disc and closely fitted with the inverted trapezoidal section is finally formed on the upper disc side slope, and stress dispersion of the upper disc is realized.

[0066] In some embodiments, in steps S6 and S9, the anchor rods of adjacent layers are arranged in a staggered manner.

[0067] Specifically, if the anchor rods of adjacent layers are arranged in alignment, a continuous gap between the anchor rods will be formed in the vertical direction, and the vertical pressure of the surrounding rock of the upper disc and the supporting reaction force of the filling body will be concentrated in the gap, which is prone to cause cracking of the surrounding rock or the filling body; staggered arrangement can disperse the stress at different vertical heights, and there is no concentrated weak area.

[0068] Specifically, in the inverted trapezoidal stope section, after the anchor rod support of the first mining layer is completed, the vertical projection position of the anchor rod of the first mining layer in the lower layer stope is marked by using a laser dot projector; after the lower layer stope is blasted and cleaned, the anchor rod point position of the current layer is determined according to the projection mark; an anchor rod machine is used to drill a hole along the point position, and a tubular slotted anchor rod and a mortar anchor rod are installed synchronously; after the installation, whether the vertical projection of the adjacent layer anchor rod is staggered is detected again by using a laser, and the anchoring force is checked, so that a support structure with staggered adjacent layer anchor rods and full-section three-dimensional staggered structure is finally formed, which adapts to the stress transmission requirements of the steeply inclined layers.

[0069] In some embodiments, with reference to Figure 1 and Figure 2Further comprising: S10, alternating operation in multiple stopes through the stope connecting road.

[0070] Illustratively, taking the main stope connecting road 41 as the transfer hub, first enter the first sublevel stope 31 through the first sublevel stope 31 connecting road 42 to carry out drilling, blasting and ore mining operations, and the ore is transported to the main stope connecting road 41 and then sent out; after the first sublevel stope 31 is mined, the filling slurry is transported through the first sublevel stope 31 connecting road 42 to complete the filling, and then enters the maintenance period. During the maintenance period of the first sublevel stope 31, the shovel and the anchor rod machine are transported to the third sublevel stope 33 connecting road 43 through the main stope connecting road 41, and then enter the third sublevel stope 33 through the connecting road to carry out the mining operation; after the third sublevel stope 33 is mined and filled, the equipment is transferred to the fourth sublevel stope 34 connecting road 44 through the main stope connecting road 41, and then enters the fourth sublevel stope 34 for operation.

[0071] When any sublevel stope maintenance is completed, the next sublevel mining can be carried out again by connecting the equipment through the corresponding sublevel stope connecting road, and the whole process relies on the main stope connecting road 41 and each sublevel stope connecting road to realize the transfer of the equipment between the first to fourth sublevel stopes 34, and ensure that each sublevel stope is connected through the corresponding connecting road to realize the alternating operation.

[0072] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed in the present application, which is within the spirit and principles of the present application, should be included in the protection scope of the present application.

[0073] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role within the technical solution range of the present application are included in the technical range of the present application. In addition, within the scope of the main idea of the present application, various modifications, combinations of part of the components in the embodiments to construct other ways can also be included in the scope of the present application.

Claims

1. A method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach, characterized in that... include: S1. Design the conversion process, comprehensively calculate the thickness of the isolation pillar when converting from the upward horizontal layered filling mining method to the downward approach method, and leave an isolation pillar between the area mined by the original upward approach method and the area mined by the current downward inverted trapezoidal long approach method. S2, Arrange the mining area and the intermediate transport roadway; S3. Set up chutes from the existing roadways along the vein of the mine, and set up multiple layered mining areas as a segment. Connect the main mining area from the segmented transport roadway to the mining area construction level of the segment within the same segment. S4. From the opening of the main stope connecting road, make a diagonal layered stope connecting road to the adjacent stope in the same zone, so that the opening area of ​​the next layered stope connecting road is located in the upper layered stope connecting road. The projections of each opening on the main stope connecting road do not overlap, and the projections of each layered stope connecting road in the vertical direction do not completely overlap. S5. Drilling and blasting are carried out from the middle of the mining area to both sides to start the first mining layer operation; S6. Support the first mining layer, use anchor bolts for the roof and lower sidewalls, and use a mixture of anchor bolts and mortar anchor bolts for the upper sidewalls. S7. Fill the first mining layer; S8. Carry out the remaining stratified mining operations; S9. Fill and support the remaining layers, and set mortar anchors near the bottom plate of the upper plate to pre-support the lower layer of the top plate.

2. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 1, characterized in that, In step S3, the vertical projections of the connecting passages between adjacent layers in the same zone and the openings connecting to the mining area do not coincide.

3. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 2, characterized in that, In step S3, among the adjacent layers of the stope connecting tunnels in the same zone, the opening between the main stope connecting tunnel and the stope is preferably located in the center of the stope.

4. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 2, characterized in that, In step S3, among the adjacent layers of the mining area connecting passages within the same zone, when the opening of one of the mining area connecting passages is located in the center of the mining area, the projection of the opening of the adjacent layer of the mining area connecting passage is adjacent to the center of the mining area and does not coincide with the opening located in the center of the mining area.

5. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 4, characterized in that, The projections between the openings of the connecting passages in the adjacent layers of the mining area do not overlap.

6. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 1, characterized in that, Step S1 also includes laying steel bars in the first layer and increasing the strength of the first mining layer and the second layer of filling material in the unmined middle section of the upper part of the fractured zone.

7. The method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach according to claim 1, characterized in that, In step S2, the cross-section of the mining area is an inverted trapezoid.

8. A method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach, as described in claim 7, is characterized in that... In steps S6 and S9, the anchor bolts on the upper plate of the inverted trapezoidal stope section are densely arranged.

9. A method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach, as described in claim 8, characterized in that... In steps S6 and S9, adjacent layered anchor bolts are arranged in an alternating pattern.

10. A method for mining and supporting steeply dipping thin veins using a downward trapezoidal long approach, as described in claim 1, characterized in that... Also includes: S10. Alternate operations are carried out in multiple mining areas via the mining area connecting road.

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