A method for controlling the subsidence of the first mining section using the downward approach filling method

Abstract

The present invention relates to a method for controlling the sinking of the first mining section by the downward approach filling method, which is characterized in that the following steps are carried out in sequence after the first layer of the first mining section is mined: (1) constructing a false roof of the first layer filling body; (2) constructing a false roof of the second layer filling body; wherein a plurality of suspension anchor cables are connected between the constructed false roof of the second layer filling body and the false roof of the first layer filling body. The present invention sets suspension anchor cables and bottom connecting anchor cables in the first and second layers of the first mining section and connects them to form a "suspension + side-pull" combined bearing structure, thereby making the first and second filling bodies in the first mining section form a load-bearing body, jointly resisting the surrounding rock convergence induced by the lower segment mining, preventing the local collapse and overall sinking of the upper segment filling body roof, ensuring the safety of the downward approach filling and mining, improving the mining efficiency of inclined and steeply inclined broken ore bodies, and reducing the mining cost of the ore body.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial false roofs, and the disclosed content relates to a mining method, and more specifically to a method for controlling the initial mining and segmented sinking using a downward approach filling method. Background Art

[0002] To ensure efficient and safe mining in underground non-coal mines under inclined, steeply inclined, and fractured surrounding rock conditions, the mainstream domestic approach is downward approach or downward stratified mining. The primary characteristic of downward mining is that operations are performed beneath the backfill roof, and the stability of the backfill roof is the primary factor limiting the safety of downward mining. However, because downward mining disturbs and closures the overlying surrounding rock, it can easily cause delamination of the backfill roof, or even widespread subsidence, severely impacting the safety and efficiency of subsequent stratified mining. In order to effectively control the stability of the filling body roof, the current representative main existing technologies are as follows: Publication No. CN115163177.A discloses "A method for constructing a filling body false roof", and proposes a filling body false roof construction process using a wire rope + steel mesh combined support structure, which reduces the labor intensity and safety risks of workers and improves the structural safety factor; Publication No. CN115263417.A discloses "A process for constructing an artificial false roof in a downward approach filling mining method", and proposes to form an artificial false roof construction method through steel mesh + reinforced concrete key layer + ordinary cementitious filling, forming a large combined reinforcement network in the entire mining area, which together with the filling body forms a complete artificial false roof.

[0003] As can be seen from the above-mentioned existing technologies, they primarily enhance the stability of individual stopes or layered fillings by adding support and reinforcement structures, which can, to a certain extent, play a role in roof maintenance. However, it should also be noted that these existing technologies fail to consider systemic stability factors and lack effective measures for maintaining overall stability. This makes it difficult to effectively address the problems of surrounding rock convergence, localized collapse of the upper layer filling roof, and overall subsidence induced by sublevel mining. Summary of the Invention

[0004] The present invention provides a method for controlling the sinking of the first mining segment by the downward approach filling method. In the first and second layers of the first mining segment, a suspension anchor cable and a bottom connecting anchor cable are arranged and connected to form a "suspension + side-pull" combined bearing structure, so that the first and second filling bodies in the first mining segment form a load-bearing body, which jointly resist the convergence of the surrounding rock induced by the lower segment mining, prevent the local collapse and overall sinking of the upper segment filling body roof, ensure the safety of the downward approach filling and mining, improve the mining efficiency of inclined and steeply inclined broken ore bodies, and reduce the mining cost of the ore body.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In order to achieve the above object, a method for controlling the subsidence of the first mining section by the downward approach filling method is provided, comprising the following steps after the first layer of the first mining section is mined:

[0007] (1) Construction of the false roof of the first layer filling;

[0008] (2) Construction of the false roof of the second layer filling;

[0009] Among them, a number of suspension anchor cables are connected between the constructed second layered filling body false top and the first layered filling body false top.

[0010] Furthermore, the construction of the false roof of the first layered filling body described in step (1) includes the following steps:

[0011] a. Installation of suspension anchor cables: On the top plate of the first layer of the first mining section of the ore body in the downward approach filling method, drill anchor holes of different depths and install the first layer suspension anchor cable corresponding to the first layer and the second layer suspension anchor cable corresponding to the second layer respectively;

[0012] b. False bottom reinforcement: First, lay the crushed ore cushion layer on the bottom plate of the first layer of the first mining section, then lay the steel mesh, and finally install the vertical reinforcement; at the same time, drill holes for anchor cables at the bottom of the side wall and the end of the first layer of the first mining section, and install the bottom connecting anchor cables;

[0013] c. Assembly: Connect the bottom connecting anchor cables with the suspension anchor cables in step a and use the steel mesh to form a three-dimensional combined support structure;

[0014] d. Filling: Construct filling retaining walls and fill the false roof mining area, thus completing the construction of the false roof of the first layer filling body.

[0015] The construction of the false top of the second layer filling body in step (2) includes the following processes: e: in the first mining section of the second layer mining route top plate of the ore body by the downward route filling method, after cleaning out the second layer suspension anchor cable reserved in the false top of the first layer filling body, then completing the false bottom reinforcement laying, assembly and filling in the second layer of the first mining section in sequence, that is, completing the construction of the false top of the second layer filling body.

[0016] Furthermore, the spacing between the suspension anchor cables is determined according to the specific mining process. The spacing between the suspension anchor cables is preferably such that 1-3 anchor cables are arranged within the width of the approach. The spacing between the suspension anchor cables is selected to be 1-2 times the width of the approach.

[0017] Furthermore, the suspension anchor cable is made of a single steel strand, wherein the portion located in the anchor cable drill hole and the portion used to connect the anchor cable to the bottom are all exposed, and the other portions are wrapped with a PVC tube;

[0018] Furthermore, grouting anchors are used in the suspension anchor cable boreholes. The grout ratio is determined according to needs, and the water-cement ratio is controlled between 0.5:1 and 1:1. The inner anchoring end in the suspension anchor cable borehole is in the form of an enlarged head, which is made by special extrusion equipment.

[0019] Furthermore, the suspension anchor cables used for the first layered approach and the suspension anchor cables used for the second layered approach should be arranged at intervals in the approach direction, and the suspension anchor cables in adjacent approaches in the same layer should be arranged at intervals in the plane;

[0020] Furthermore, the suspension anchor cable hole depth for the first layered approach is smaller than the suspension anchor cable hole depth for the second layered approach.

[0021] Furthermore, in step c, the bottom connecting anchor cable arranged along the direction of the access route is made of a single steel strand. Grouting anchor cables are used in the bottom connecting anchor cable drill holes, with the grout ratio determined as needed, and the water-cement ratio controlled between 0.5:1 and 1:1. The inner anchor end in the hole is in the form of an enlarged head, produced using specialized extrusion equipment.

[0022] Furthermore, the length of the bottom connecting anchor cable arranged perpendicular to the direction of the access road is slightly longer than the width of the access road. The anchor cable longer than the width of the access road needs to be wrapped with a flexible PVC tube for protection to avoid being cemented into the filling body.

[0023] The bottom connecting anchor cables arranged horizontally and vertically must be effectively connected; the suspension anchor cables and the bottom connecting anchor cables must be effectively connected; the suspension anchor cables must be kept vertical.

[0024] In the step d, the filling in the mining access road can be layered in the vertical direction, the strength of the lower filling body is not less than 3-5MPa, the height is greater than 1 / 3 of the tunnel height, and the strength of the upper filling body can be appropriately reduced.

[0025] Beneficial effects of the present invention:

[0026] The present invention adopts a combined load-bearing mode by reinforcing the lower filling body of the approach + multi-layer and multi-mining field joint suspension, so that the multiple layered filling bodies in the first mining segment form a load-bearing body, jointly resisting the surrounding rock convergence induced by the lower segment mining, preventing the local collapse and overall sinking of the upper segment filling body top plate, ensuring the safety of the downward approach filling and mining, improving the mining efficiency of inclined and steeply inclined broken ore bodies, and reducing the mining cost of the ore body.

[0027] The present invention provides a method for controlling the sinking of the first mining segment using the downward approach filling method, which is suitable for filling and reclaiming mines under inclined, steeply inclined, and surrounding rock crushing conditions in non-coal mines, and is particularly suitable for the first mining segment using the downward approach filling method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is a schematic diagram of the cross-sectional structure along the dip of the ore body provided in an embodiment of the present invention.

[0029] Figure 2 A schematic diagram of a vertical cross-sectional structure provided by an embodiment of the present invention.

[0030] Figure 3 A schematic diagram of the cross-sectional structure along the strike of the ore body provided in an embodiment of the present invention.

[0031] In the figure: 1-first layer; 2-second layer; 3-approach being mined; 4-approach to be mined; 5-filled approach; 6-ore body; 7-suspending anchor of first layer; 8-suspending anchor of second layer; 9-bottom connecting anchor; 10-anchor rod; 11-mesh; 12-crushed ore cushion; 13-vertical reinforcement; 14-connecting piece between the suspension anchor of first layer and the bottom connecting anchor; 15-hole position of the suspension anchor of second layer; 16-filling body. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0033] This embodiment provides a method for controlling the first mining and subsidence by a downward approach filling method. Figure 1-Figure 3 As shown, after the first mining section and the first layer of the ore are mined, the following steps are carried out:

[0034] (1) Suspension anchor cable steps: First, multiple first-layer suspension anchor cables 7 and second-layer suspension anchor cables 8 are installed on the first-layer access road top plate, and each suspension anchor cable 7, 8 is fixed in the surrounding rock;

[0035] (2) False bottom reinforcement step: laying crushed ore cushion layer 12 on the first layer access road bottom plate, connecting anchor cable 9 at the bottom of the construction, laying steel mesh 11, installing anchor rod 10, and installing vertical reinforcement 13;

[0036] (3) Assembly and protection steps: connect the suspension anchor cable 7 or 8 with the bottom connecting anchor cable 9 to form a three-dimensional combined structure;

[0037] (4) Filling step: Construct the filling retaining wall and fill the false roof stope, thus completing the construction of the false roof of the first layer filling body.

[0038] After completing the construction of the false top of the first-layer filling body, the second-layer mining access top plate of the first-layer mining section of the ore body is mined by the downward access filling method, and the second-layer suspension anchor 8 reserved in the false top of the first-layer filling body is cleared out. Then, the false bottom reinforcement, assembly and filling are completed in the second layer of the first mining section in sequence, thus completing the construction of the false top of the second-layer filling body.

[0039] The above-mentioned filling body anti-sinking method is mainly aimed at the situation where the first section of underground non-coal soft and broken ore bodies is mined using a downward approach or layered filling method.

[0040] The above method sets the first layer suspension anchor 7, the second layer suspension anchor 8 and the bottom connecting anchor 9 in the first and second layers of the first mining section, and connects them to form a "suspension + side pull" combined bearing structure, so that the multiple layered filling bodies in the first mining section form a load-bearing body, and jointly resist the surrounding rock convergence induced by the lower section mining.

[0041] The anti-sinking method of filling body proposed in the present invention can effectively exert the overall bearing effect of different layered filling bodies in the first mining section, prevent the local collapse and overall sinking of the upper section filling body roof, ensure the safety of the downward approach filling and mining, improve the mining efficiency of inclined and steeply inclined broken ore bodies, and reduce the mining cost of the ore body.

[0042] The following is a specific example to illustrate the above-mentioned method for preventing the filling body from sinking:

[0043] A large underground metal mine produces approximately 600,000 tons of ore annually, with high grade and value. The main ore body to be mined is approximately 200 meters long along strike, buried approximately 1,500 meters deep, and has a thickness ranging from 5.54 to 39.54 meters, with an average thickness of 20.82 meters.

[0044] The ore body is moderately inclined to inclined, with a dip angle of about 53° to 80°.

[0045] The surrounding rock of the ore body is primarily composed of medium-crystalline dolomite interbedded with multiple layers of shale and thin layers of carbonaceous shale. Deep ore mining is prone to collapse and roof falls. Furthermore, collapse can occur when mining passes through fault zones. The ore body, located within the Zaig Formation, occurs in layered, lenticular, and tubular forms. Joints, fissures, and small faults are well-developed, dissecting the ore body and compromising its integrity. The overall strength distribution of the ore body is uneven, and the engineering geological conditions are classified as moderately complex.

[0046] Based on factors such as the ore body occurrence morphology, ore rock stability, depletion index requirements, and production capacity, the mine is currently designed to adopt a downward approach filling mining method.

[0047] Using the filling body anti-sinking method provided in the above embodiment, the example mine adopts the present invention as follows Figures 1 to 3 The method for preventing the filling from sinking shown in the figure specifically includes the following steps and requirements:

[0048] (1) If Figures 1 to 3As shown, the initial mining section of the example mine is divided into four horizontal layers. The first layer access route is arranged along the strike of the ore body, and the subsequent layer access routes are arranged vertically and crosswise. In this example, the access route is 33m long, 3m wide, and 3m high. Two layers have been mined, using a side-to-side mining sequence. Starting from the third layer, a "mining one after another" mining sequence is adopted. The middle stope is currently mining stope 3, and the adjacent stopes 5 are currently mining and filling.

[0049] (2) In this case, a row of anchor cables is arranged at the center of the top plate of the first layer of the first mining section, and 6m and 8m anchor cable holes are constructed respectively, with a spacing of 3m, for installing the first layer suspension anchor cable 7 and the second layer suspension anchor cable 8; the anchor cables are made of single steel strands bonded together over the entire length, with a diameter of φ21.80mm and a length of 9m and 14m respectively. Enlarged heads are set at the ends and arranged vertically at intervals within the range of the route direction; the 14m anchor cable head is covered with a PVC pipe 3m away and sealed to avoid bonding in the filling body.

[0050] (3) In this case, a 10-20 cm layer of crushed ore cushion is first laid on the bottom plate of the first mining section and the first layer of the mining access road. A steel mesh 11 is laid on it. The steel mesh 11 is prefabricated and welded with φ6 mm steel bars. The mesh size is 1 m × 2 m, and the mesh parameter is 100 mm. Three mesh holes are overlapped between the meshes and tied with three lead wires. 1.5 m above the wall of the mesh on the side close to the surrounding rock, a φ40 pipe seam anchor rod 10 is fixed and pressed on the side wall. The spacing between rows is 1.0 m and the length is 1.6 m.

[0051] (4) In this case, at the bottom of the side wall of the first layer of the first mining section, a row of 4m long anchor cable holes were constructed with a spacing of 3m for installing the bottom connecting anchor cable 9. The anchor cable was made of a single steel strand with full-length adhesive bonding. The diameter of the anchor cable was φ21.80mm and the length was 29m. An enlarged head was set at the end and it was horizontally arranged within the range of the approach. A PVC pipe was placed at the 22m position of the anchor cable head and sealed to avoid adhesive bonding in the filling body. At both ends of the approach direction, 4m long anchor cable holes were constructed for installing the bottom connecting anchor cable 9. The anchor cable was made of a single steel strand with full-length adhesive bonding. The diameter of the anchor cable was φ21.80mm and the length was 41m. An enlarged head was set at the end and it was horizontally arranged within the range of the approach. The bottom connecting anchor cable 9 and the first layer suspension anchor cable 7 were fastened together with anchor cable connectors to form a three-dimensional combined bearing structure. Install two rows of vertical reinforcements 13 in the access road. The vertical reinforcements 13 are prefabricated with φ12mm threaded steel bars, with a length of 1.6m and a spacing of 1.0m×1.0m. Cross members are welded at the ends. The cross members are prefabricated with φ12mm threaded steel bars and have a length of 200mm.

[0052] (5) In this case, after the completion of the "suspension + side pull" combined bearing structure, the retaining wall construction at the end of the access road was started, and the high-concentration tailings cementing filling work began. When filling the access road, the filling material slurry with a lime-sand ratio of 1:4 to 1:5 was first used to fill the base layer to 1.5m, and then the filling material slurry with a ratio of 1:8 to 1:10 was used to fill the top, completing the first access road mining and filling.

[0053] (6) In this case, after the first access road is mined and backfilled for 7 days, the adjacent second access road is mined. The suspension anchors 7 and 8 are still arranged in step (2). In step (3), the anchor net is laid and the net is tied to the first access road net with lead wire. The bottom connecting anchor 9 in step (4) is cleared out and connected to the first layer suspension anchor 7. The second layer suspension anchor 8 is still protected, and step (5) is completed.

[0054] (7) In this case, repeat step (6), and continuously mine in the first layer of the first mining section, and fill after mining to complete the prevention and control work of the first layer of the first mining section;

[0055] (8) In this case, the suspension anchor cable 8 reserved in the filling body was cleared out from the top plate of the second layer of the first mining section. Steps (3) to (6) were repeated to complete the prevention and control work of the second layer of the first mining section. A "suspension + side pull" combined bearing structure was formed, so that the two layered filling bodies in the first mining section formed a load-bearing body, jointly resisting the surrounding rock convergence induced by the mining of the lower section.

[0056] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for controlling the first mining and subsidence by a downward approach filling method, characterized in that: After the first mining section and first layer are mined, the following steps are carried out in sequence: (1) Construction of the false roof of the first layer filling; The construction of the first layered filling body false roof in step (1) includes the following steps: a. Installation of suspension anchor cables: On the top plate of the first layer of the first mining section of the ore body in the downward approach filling method, drill anchor cables at different depths and install the first layer suspension anchor cable corresponding to the first layer and the second layer suspension anchor cable corresponding to the second layer respectively; b. False bottom reinforcement: First, lay the crushed ore cushion layer on the bottom plate of the first layer of the first mining section, then lay the steel mesh, and finally install the vertical reinforcement; at the same time, drill holes for anchor cables at the bottom of the side wall and the end of the first layer of the first mining section, and install the bottom connecting anchor cables; c. Assembly: Connect the bottom connecting anchor cable with the first layer suspension anchor cable and the second layer suspension anchor cable in step a, and use the steel mesh to form a three-dimensional combined support structure; d. Filling: Constructing filling retaining walls and filling the false roof stope, thus completing the construction of the false roof of the first layer filling body; (2) Construction of the false roof of the second layer filling; The construction of the second layered filling body false roof in step (2) includes the following steps: e. Using the downward approach filling method to recover the top plate of the second layer of the first mining section of the ore body, after clearing out the second layer suspension anchor cable reserved in the false top of the first layer filling body, the false bottom reinforcement, assembly and filling are completed in sequence in the second layer of the first mining section, thus completing the construction of the false top of the second layer filling body; Among them, a number of suspension anchor cables are connected between the constructed second layered filling body false top and the first layered filling body false top.

2. The method for controlling the first mining and subsidence by the downward approach filling method according to claim 1 is characterized in that: In step a: the suspension anchor cable is made of a single steel strand, wherein the portion located in the anchor cable drill hole and the portion used to connect to the bottom anchor cable are all exposed, and the other portions are wrapped with a PVC tube.

3. The method for controlling the first mining and subsidence by the downward approach filling method according to claim 1 is characterized in that: The depth of the hole used to install the first layered suspension anchor is less than the depth of the hole used to install the second layered suspension anchor.

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