Backfilling mining method for steeply inclined coal seams

Abstract

The application discloses a filling mining method of steeply inclined coal seam and relates to the technical field of coal mining. The method comprises the following steps: dividing each stage of the steeply inclined coal seam into upper layers, middle layers and lower layers; mining the upper layers, the middle layers and the lower layers; and forming a filling mining method of the steeply inclined coal seam with a sandwich type protection structure and a Z type filling structure during the mining process. The sandwich type protection structure is formed by consolidating a coal pillar, surrounding rock and concrete together, which can effectively protect the coal pillar from damage and maintain the stability of the mined-out area. The Z type filling body structure is formed by combining a reserved coal pillar, lower concrete and an inclined concrete column. The Z type filling body structure has a reserved coal pillar on the top and the bottom, and compared with other filling body structures, the Z type filling body structure formed by combining mining and filling is safer. The filling mining method of the steeply inclined coal seam can maintain the stability of the mined-out area and is beneficial to safe mining.

Description

Backfilling mining method for steeply inclined coal seams Technical Field

[0001] This invention relates to the field of coal mining technology, specifically to a method for backfilling mining of steeply inclined coal seams. Background Technology

[0002] Steeply inclined coal seams refer to coal seams with a dip angle greater than 45 degrees during underground mining. When the dip angle is large, the mining of steeply inclined coal seams exhibits asymmetrical characteristics along the dip direction. This causes the rockfall from the upper part of the working face to slide to the lower part after mining, creating a backfilling effect in the lower part of the working face. The upper part of the working face is equivalent to an increased mining height, resulting in the height of the collapse zone and fracture zone being higher than that below. After the coal body is mined out, the goaf pillar becomes the main support of the overlying strata. When mining is carried out in a small area (with a small number of goafs), the mining-induced fractures are not easy to penetrate to the surface, and the stress concentration of the supporting coal and rock mass is relatively small, with compression deformation being small-scale continuous deformation. As the number of mining faces increases, the supporting coal and rock mass is not only affected by the force of the sliding rockfall from the lower part of the goaf in the upper section, the force of the overlying strata, and its own weight, but also by the superposition of mining-induced stress from multiple working faces, seriously affecting mining and surface safety.

[0003] Currently, the main technologies for mining steeply inclined coal seams include: longwall mining and pseudo-inclined flexible shield support mining. However, these mining methods involve a lot of work, such as widening the roadway, digging trenches, laying shield supports, and placing coal under the shield supports. These methods all involve high labor intensity and technical problems. Moreover, as the amount of mining work increases, the supporting coal and rock mass becomes unstable, which is not conducive to safe mining.

[0004] This shows that the existing technology needs further improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a method for backfilling mining of steeply inclined coal seams, which can maintain the stability of the goaf and facilitate safe mining.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A backfilling mining method for steeply inclined coal seams, which mines the steeply inclined coal seams by forming a sandwich-type protective structure, and the mining method includes the following steps:

[0008] Step 1: Divide the steeply inclined coal seam into several stages from top to bottom. Each stage includes an upper layer, a middle layer, and a lower layer from top to bottom.

[0009] Step 2: Reserve the first coal pillar at the top of the upper layer, mine the upper layer, and a goaf is formed in the upper layer after mining;

[0010] Step 3: Install grouting anchor cables in the upper and lower wall surrounding rocks of the upper layer of the goaf, and arrange steel bars in the goaf. Fix the ends of the steel bars to the grouting anchor rods. At the same time, install grouting anchor cables to the first coal pillar above, so that the grouting anchor cables at the first coal pillar are connected to the steel bars.

[0011] Step 4: Fill the upper layer of mined-out area with concrete and wait for the concrete to solidify;

[0012] Step 5: The consolidated concrete and the first coal pillar together form an artificial false roof structure. Under the protection of this artificial false roof structure, the mining of the middle layer continues. After the middle layer is mined, the mining of the next layer continues.

[0013] Step Six: After the lower layer is mined out, follow the steps in Steps Three and Four in the goaf of the lower layer so that the concrete and the coal pillar located below the concrete together form an artificial false roof structure.

[0014] Step 7: Repeat steps 1 through 6 to proceed to the next stage of mining.

[0015] In the above-mentioned method for backfilling and mining steeply inclined coal seams, the thickness of the upper layer is 2-3m, the thickness of the lower layer is the same as the thickness of the upper layer, and the thickness of the middle layer is greater than the thickness of the upper layer.

[0016] In the above-mentioned method for backfilling and mining steeply inclined coal seams, the concrete has a strength of C30 or higher.

[0017] In the above-mentioned method for backfilling and mining steeply inclined coal seams, the upper and lower grouting anchor bolts of the same coal pillar are arranged in an alternating manner.

[0018] In the above-mentioned method for backfilling and mining steeply inclined coal seams, the spacing between the grouting anchor cables on both sides is 0.8 to 1.0 m.

[0019] Another object of the present invention is to provide a method for backfilling mining of steeply inclined coal seams, which mines steeply inclined coal seams by forming a Z-shaped backfilling structure. The mining method includes the following steps:

[0020] Step 1: Divide the steeply inclined coal seam into several stages from top to bottom. Each stage includes an upper layer, a middle layer, and a lower layer from top to bottom.

[0021] Step 2: Reserve the first coal pillar at the top of the upper layer, mine the upper layer, and a goaf is formed in the upper layer after mining;

[0022] Step 3: Install grouting anchors at the upper and lower wall surrounding rocks of the upper layer of the goaf, arrange steel bars in the goaf of the first section, and connect and fix the two ends of the steel bars to the grouting anchors. Reserve steel bar interfaces at the upper wall surrounding rock for the upper layer of the steel bars.

[0023] Step 4: Fill the upper layered goaf with concrete and wait for the concrete to solidify. The first coal pillar and the concrete above the goaf together form an artificial false roof.

[0024] Step 5: Under the artificial false roof in Step 4, the middle layer is mined. After the middle layer is mined, reinforced concrete columns are poured on both sides of the goaf of the middle layer. The steel reinforcement skeleton of the concrete column is connected to the steel reinforcement interface of the upper layer. The concrete column is arranged at an angle, from the upper wall of the upper layer to the lower wall of the middle layer in the opposite direction.

[0025] Step 6: Without waiting for the reinforced concrete column to stabilize and solidify, continue mining the lower layer. After the lower layer is mined, install grouting anchors and concrete using the same method as the upper layer. The concrete below the first coal pillar, the concrete column, and the concrete in the lower layer goaf together form a Z-shaped filling structure, and the Z-shaped filling structure is further supported by the first coal pillar and the coal pillar below the lower layer goaf.

[0026] Step 7: Repeat steps 1 to 6 to continue mining the next stage until all stages of mining are completed.

[0027] In the above-mentioned method for backfilling and mining steeply inclined coal seams, in step three, after the two ends of the reinforcing bar are connected and fixed together with the grouting anchor rod, grouting anchor cables are simultaneously driven into the first coal pillar to connect the grouting anchor cables with the reinforcing bar.

[0028] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0029] This invention proposes a backfilling mining method for steeply inclined coal seams. This method mines steeply inclined coal seams by forming a sandwich-type protective structure. Concrete is constructed above and below the steeply inclined coal pillar, along with grouting anchor bolts and cables, to solidify the coal pillar, surrounding rock, and concrete together into a sandwich-type protective structure. This effectively protects the coal pillar from damage and maintains the stability of the goaf. When mining steeply inclined coal seams using this sandwich-type protective structure, the seam is first divided into several stages. Each stage is then further divided into upper, middle, and lower layers. Through a self-designed mining method combined with goaf backfilling, the coal pillar, surrounding rock, and concrete are solidified together to form the sandwich-type protective structure. This backfilling mining method of the present invention offers high mining efficiency and greater safety.

[0030] The sandwich-type protective structure, because its concrete forms an integral whole with the upper and lower coal pillars and surrounding rock, saves the manpower and physical resources required for separate support compared to other filling structures, reduces the workload, and enables safe mining.

[0031] This invention also proposes another method for backfilling mining of steeply inclined coal seams. This method involves mining steeply inclined coal seams by forming a Z-shaped backfill structure. It achieves this by rationally dividing the mining area and forming a Z-shaped backfill structure within the excavated goaf, combining "pre-reserved coal pillars with upper and lower concrete and inclined concrete pillars." This is further enhanced by grouting anchor bolts and cables to maintain the stability of the coal pillars and goaf in the steeply inclined goaf, preventing disasters. When mining steeply inclined coal seams using the Z-shaped backfill structure, the seam is first divided into several stages, and each stage is further divided into upper, middle, and lower layers. Through a unique mining method combined with goaf backfilling, a Z-shaped backfill structure is formed, combining pre-reserved coal pillars with upper and lower concrete and inclined concrete pillars. This backfilling mining method of this invention offers high mining efficiency and greater safety.

[0032] The Z-shaped filling structure has pre-reserved coal pillars at both the top and bottom. Compared with other filling structures, the Z-shaped filling structure formed by combining mining and filling is safer and saves the manpower and material resources required for separate support.

[0033] The backfilling mining method of this invention has high safety and can be applied to the mining of steeply inclined coal seams. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings:

[0035] Figure 1 is a schematic diagram of the filling and mining process of the Z-type filling structure of the present invention;

[0036] Figure 2 is a side view of the Z-type filling structure of the present invention during a certain stage of mining;

[0037] Figure 3 is a schematic diagram of the stage layering of the Z-type filling structure of the present invention;

[0038] Figure 4 is a schematic diagram of the upper-layer mining of the Z-type filling structure of the present invention;

[0039] Figure 5 is a schematic diagram of the mid-layer mining of the Z-type filling structure of the present invention;

[0040] Figure 6 is a schematic diagram of the lower-layer mining of the Z-type filling structure of the present invention;

[0041] Figure 7 is a schematic diagram of the backfilling and mining of the sandwich-type protective structure of the present invention;

[0042] Figure 8 is a schematic diagram of the layered division of the sandwich-type protective structure of the present invention.

[0043] Figure 9 is a schematic diagram of the sandwich-type protective structure of the present invention after a certain stage of mining.

[0044] In the picture:

[0045] 1. Surrounding rock, 2. Goaf, 3. Coal pillar, 4. Grouting anchor, 5. Upper layer, 6. Middle layer, 7. Lower layer. Detailed Implementation

[0046] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0047] The coal pillars mentioned in this invention can represent the coal pillar at the top of the upper layer or the coal pillar at the bottom of the lower layer in each stage; the coal pillars can also be further distinguished, such as the coal pillar at the top of the upper layer being the first coal pillar and the coal pillar at the bottom of the lower layer being the second coal pillar.

[0048] The upper, middle, and lower layers mentioned in this invention can also be referred to as the first segment, the second segment, and the third segment, respectively.

[0049] Referring to Figures 1 to 6, the filling mining method for steeply inclined coal seams based on a Z-shaped filling structure of the present invention includes the following steps:

[0050] Step 1: Divide the steeply inclined coal seam into several stages from top to bottom. Each stage includes the upper layer 5, the middle layer 6, and the lower layer 7 from top to bottom.

[0051] Step 2: Reserve a coal pillar 3 at the top of the upper layer, mine the upper layer, and after mining, a goaf 2 will be formed in the upper layer;

[0052] Step 3: Install grouting anchor bolts 4 at the upper and lower wall surrounding rock 1 of the upper layer goaf area, arrange steel bars in the goaf area of ​​the first section, and connect and fix the two ends of the steel bars to the grouting anchor bolts. The steel bars of the upper layer have steel bar interfaces reserved at the upper wall surrounding rock. After the two ends of the steel bars are connected and fixed to the grouting anchor bolts, grouting anchor cables are driven into the first coal pillar at the same time, and the grouting anchor cables are connected to the steel bars.

[0053] Step 4: Fill the upper layered goaf with concrete and wait for the concrete to solidify. The first coal pillar and the concrete above the goaf together form an artificial false roof. The artificial false roof can further ensure the safe mining of the middle layer in the later stage. Moreover, by injecting concrete to fill the goaf while mining, the work efficiency can be improved.

[0054] Step 5: Under the artificial false roof in Step 4, the middle layer is mined. After the middle layer is mined, reinforced concrete columns are poured on both sides of the goaf of the middle layer. The steel reinforcement skeleton of the concrete column is connected to the steel reinforcement interface of the upper layer. The concrete column is arranged at an angle, from the upper wall surrounding rock of the upper layer to the lower wall surrounding rock of the middle layer in the opposite direction. The angled arrangement can make the formed filling structure more stable and improve the support effect.

[0055] Step 6: Without waiting for the reinforced concrete column to stabilize and solidify, continue mining the lower layer. After the lower layer is mined, install grouting anchors and concrete using the same method as the upper layer. The concrete below the first coal pillar, the concrete column, and the concrete in the lower layer goaf together form a Z-shaped filling structure, and the Z-shaped filling structure is further supported by the first coal pillar and the coal pillar below the lower layer goaf.

[0056] Step 7: Repeat steps 1 to 6 to continue mining the next stage until all stages of mining are completed.

[0057] In the above method, the minimum strength of the concrete is C30, but it can also be C50 or C60 concrete.

[0058] Preferably, the thickness of the upper layer is 2-3m, the thickness of the lower layer is the same as the thickness of the upper layer, and the thickness of the middle layer is greater than the thickness of the upper layer. For example, the thickness of the middle layer is 3-5 times the thickness of the upper layer. After the middle layer is mined, concrete columns formed by injecting concrete into the goaf formed after the middle layer is mined can form a support system with the concrete in the upper goaf and the concrete in the lower goaf, which improves the efficiency of coal mining while ensuring the safety of coal mining.

[0059] Preferably, the upper and lower grouting anchor bolts of the same coal pillar are arranged in a staggered manner to facilitate better support.

[0060] Preferably, the spacing between the grouting anchor cables on both sides is 0.8 to 1.0 m.

[0061] The coal pillars mentioned in this invention can represent the coal pillar at the top of the upper layer or the coal pillar at the bottom of the lower layer in each stage; the coal pillars can also be further distinguished, such as the coal pillar at the top of the upper layer being the first coal pillar and the coal pillar at the bottom of the lower layer being the second coal pillar.

[0062] The upper, middle, and lower layers mentioned in this invention can also be referred to as the first segment, the second segment, and the third segment, respectively.

[0063] Referring to Figures 7 to 9, the present invention provides a method for backfilling and mining steeply inclined coal seams with a sandwich-type protective structure, which specifically includes the following steps:

[0064] Step 1: Divide the steeply inclined coal seam into several stages from top to bottom. Each stage includes an upper layer 6, a middle layer 7, and a lower layer 8 from top to bottom. The thickness of the upper layer is 2-3m, the thickness of the lower layer is the same as that of the upper layer, and the thickness of the middle layer is greater than that of the upper layer.

[0065] Step 2: Reserve the first coal pillar at the top of the upper layer, mine the upper layer, and after mining, a goaf 2 will be formed in the upper layer;

[0066] Step 3: Install grouting anchor cables 5 at the upper and lower wall surrounding rock 1 of the upper layer goaf. Multiple grouting anchor cables are installed, with a distance of 0.8 to 1m between adjacent grouting anchor cables. Reinforcing bars are arranged in the goaf and fixedly connected to the grouting anchor rods 4 at the ends of the reinforcing bars. At the same time, install grouting anchor cables to the first coal pillar above, so that the grouting anchor cables at the first coal pillar are connected to the reinforcing bars.

[0067] Step 4: Fill the upper layer of goaf with concrete and wait for the concrete to solidify; in this way, the concrete is solidified together with the first coal pillar above the upper layer of goaf by grouting anchor bolts and grouting anchor cables, forming a stable artificial false roof structure.

[0068] Step 5: Under the protection of the artificial false roof structure, continue mining the middle layer. After the middle layer is mined, there is no need to fill the goaf area, and the next layer can be mined.

[0069] Step Six: After the lower layer of mining is completed, an artificial false roof structure is arranged again in the goaf of the lower layer. Specifically, grouting anchor cables are driven into the upper and lower wall surrounding rocks of the goaf of the lower layer, and steel bars are arranged in the goaf. The ends of the steel bars are fixedly connected to the grouting anchor rods. At the same time, grouting anchor cables are driven into the coal pillar below, so that the grouting anchor cables are connected to the steel bars. Then, concrete is filled into the goaf and waits for the concrete to solidify. The solidified concrete and the coal pillar together form a stable artificial false roof structure.

[0070] Step 7: Repeat steps 1 through 6 to proceed to the next stage of mining.

[0071] In summary, this invention employs a novel method for filling coal seams during steeply inclined mining. By creating a coal pillar and a concrete filling structure to form an artificial false roof during mining, it can improve mining efficiency and ensure safe mining of coal seams.

[0072] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. A method for backfilling and mining steeply inclined coal seams, characterized in that, It mines steeply inclined coal seams by forming a Z-shaped filling structure. The mining method includes the following steps: Step 1: Divide the steeply inclined coal seam into several stages from top to bottom, where each stage includes an upper layer, a middle layer, and a lower layer from top to bottom; Step 2: Reserve the first coal pillar at the top of the upper layer, mine the upper layer, and form a goaf in the upper layer after mining; Step 3: Install grouting anchors at the upper and lower wall surrounding rocks of the goaf in the upper layer, arrange steel bars in the goaf of the first section, and connect and fix the two ends of the steel bars to the grouting anchors. The steel bar interfaces of the upper layer are reserved at the wall surrounding rocks; Step 4: Fill the goaf of the upper layer with concrete and wait for the concrete to solidify. The first coal pillar and the concrete above the goaf together form an artificial false roof; Step 5: In step 4, the first coal pillar and the middle layer are filled with concrete. In the mining process, the middle layer is mined under the top of the working-class coal seam. After the middle layer is mined, reinforced concrete columns are poured on both sides of the goaf of the middle layer. The steel reinforcement skeleton of the concrete column is connected to the steel reinforcement interface of the upper layer. The concrete column is arranged at an angle, from the upper wall of the upper layer to the lower wall of the middle layer in the opposite direction. Step six: Without waiting for the reinforced concrete column to stabilize and solidify, the mining of the lower layer continues. After the lower layer is mined, the same method as the upper layer is used to install grouting anchors and concrete. The concrete below the first coal pillar, the concrete column, and the concrete in the goaf of the lower layer together form a Z-shaped filling structure, and the Z-shaped filling structure is further supported by the first coal pillar and the coal pillar below the goaf of the lower layer. Step seven: Repeat steps one to six to continue mining the next stage until all stages of mining are completed.

2. The backfilling mining method for steeply inclined coal seams according to claim 1, characterized in that: In step three, after the two ends of the reinforcing bar are connected and fixed together with the grouting anchor rod, grouting anchor cables are simultaneously driven into the first coal pillar to connect the grouting anchor cables with the reinforcing bar.

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