A non-typical key layer filling mining method for coal mines

Abstract

The present invention discloses a method for backfilling mining of a non-typical key layer of a coal mine, comprising the following steps: (1) determining a backfilling mining area, and dividing the area into strips based on the requirements for surface subsidence control; (2) performing strip mining in the backfilling mining area; (3) performing grouting filling on the goaf formed after strip mining, wherein the grouting amount is 35-38% of the volume of the mined coal; (4) performing grouting filling on the goaf of the mined strip while performing mining on adjacent strips; (5) repeating steps (2)-(4) to complete the backfilling mining operation. The method of the present invention is simple in construction, and backfilling mining is performed on non-typical key layers, which can effectively reduce the overburden collapse angle and collapse height, limit the lateral collapse and deformation of coal and rock pillars, make the collapse space of adjacent working faces unable to penetrate, reduce ground deformation and subsidence, improve the coal recovery rate, ensure the safety of construction personnel, and improve the ecological environment protection effect.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a non-typical key layer filling mining method for a coal mine. Background Art

[0002] The development of coal resources inevitably causes serious damage to the land ecology. With the increasing attention paid to the construction of ecological civilization, the existing technology has studied the problem of mining subsidence in coal mining areas and proposed a variety of mining subsidence prediction methods. When the coal mine goaf is large enough, the movement and destruction of the rock strata develop to the surface, forming a subsidence basin much larger than the goaf on the surface, and causing a series of mining damage problems. Practice has shown that the breakage of each hard rock layer in the overlying rock strata and the recombination of broken rock blocks during mining not only affect the redistribution and rebalance of the overlying rock stress, but also affect the evolution of rock strata movement and mining damage problems.

[0003] The key layer theory is a result of the active theoretical exploration and practice in this field to solve the problems of rock movement and mining damage as the social productivity develops to a certain stage. In the mining process of the lower coal seam in the shallow coal seam group, the key layer refers to the thick and hard rock layer or rock layer group in the interval rock layer that plays an effective roof control role after the thickness of the interval rock layer is deducted from the height of the collapse zone of the lower coal seam and the depth of the destruction of the floor of the upper coal seam. The atypical key layer refers to the interval rock layer between the upper and lower coal seams with a small thickness, a large mining height of the lower coal seam, and a direct collapse of the collapse zone of the lower coal seam through the interval rock layer, and there is no control structure in the interval rock layer. Under such conditions, if there is a thick and hard rock layer in the interval rock layer, the thick and hard rock layer collapses in the form of a cantilever beam to form a step rock beam structure; if there is no thick and hard rock layer in the interval rock layer, the roof of the interval rock layer cannot form a stable structure, and the disturbed key layer that can form a structure in the upper coal seam will play a control role in the mining area of ​​the lower coal seam.

[0004] If the atypical key layers are not effectively controlled during the mining process, the overburden collapse angle and collapse height will increase, the lateral collapse and deformation of the coal and rock pillars will increase, and the collapse space of adjacent working faces will be connected, thereby causing ground deformation and subsidence, which will have a significant impact on mining results, personnel safety and the ecological environment. Summary of the invention

[0005] In order to solve the defects in the prior art, the present invention provides a method for backfilling mining of atypical key layers in coal mines. The method of the present invention is simple to construct, and backfilling mining is performed on atypical key layers, which can effectively reduce the collapse angle and collapse height of the overburden, limit the lateral collapse and deformation of the coal and rock pillars, make the collapse space of adjacent working faces unable to penetrate, reduce ground deformation and subsidence, improve coal recovery rate, ensure the safety of construction personnel, and improve the ecological environment protection effect.

[0006] To achieve the above object, the present invention provides a method for backfilling mining of a non-typical key layer of a coal mine, comprising the following steps:

[0007] (1) Determine the backfill mining area and divide it into strips based on the requirements for surface subsidence control; first determine the thickness of the atypical key layer, and determine the backfill mining area based on the thickness of the atypical key layer. The backfill mining area is the area with a certain width expanded from the larger area of ​​the upper and lower coal seams;

[0008] (2) Strip mining is carried out in the filling mining area; when strip mining is carried out, the top of the surrounding rock of the goaf formed after strip mining is supported, and a lateral isolation support structure is set on the side of the goaf adjacent to the next mining strip;

[0009] (3) Grouting is performed to fill the goaf formed after strip mining, with the grouting volume being 35-38% of the mined coal volume; the grouting material is transported to the goaf formed after strip mining through a grouting pipe, and different grouting filling methods are used for the goaf according to the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam;

[0010] (4) While grouting the goaf of the mined strip, mining is carried out in the adjacent strip; during this process, the subsidence of the surface of the filled mining area is continuously observed;

[0011] (5) Repeat steps (2) to (4) to eventually fill all the goafs formed after all strip mining, thus completing the backfill mining operation.

[0012] Preferably, in step (1), the filling mining area is, when the thickness of the atypical key layer is less than 6m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 22-25m; when the thickness of the atypical key layer is 6-9m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 18-20m.

[0013] In any of the above schemes, it is preferred that, in step (1), the surface subsidence control requirement is based on the surface maximum subsidence control requirement; subsidence observation lines are arranged on the surface, including a plurality of longitudinal survey lines located at the boundaries of each strip along the mining direction and transverse survey lines perpendicular thereto, and the number of longitudinal survey lines and transverse survey lines is the same.

[0014] In any of the above schemes, it is preferred that in step (2), the lateral isolation support structure is arranged along the travel direction of the goaf, and the goaf section height of the strip is 5-6 meters and the width is 7-8 meters.

[0015] In any of the above schemes, it is preferred that in step (2), the support strength of the top of the surrounding rock is determined according to the allowable value of the settlement of the coal seam roof in the filling mining area, and the lateral isolation support structure is set according to the support strength of the top of the surrounding rock, the geological structure characteristics of the mining space, the flow and solidification bearing characteristics of the grouting material, and the pressure. The lateral isolation support structure can resist the maximum pressure of the grouting material.

[0016] In any of the above schemes, it is preferred that in step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is less than 3, the goaf formed after strip mining is grouting-filled three times, the grouting volume of the first filling is 1 / 3 of the total grouting volume, the grouting volume of the second filling is 2 / 5 of the total grouting volume, and the third filling is the remaining grouting volume.

[0017] In any of the above schemes, it is preferred that in step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is greater than or equal to 3 and less than 5, the goaf formed after strip mining is grouting-filled twice, the grouting volume of the first filling is 1 / 2 of the total grouting volume, and the second filling is the remaining grouting volume.

[0018] In any of the above schemes, it is preferred that in step (3), when grouting filling is performed, the next grouting filling is performed after each grouting material is solidified, and the solidification time of the grouting material is 12-15 hours.

[0019] In any of the above schemes, it is preferred that the water-cement ratio of the grouting material is 5:2, and the grouting material includes the following components in parts by weight: 50-60 of cement, 22-25 of bauxite, 15-20 of limestone, 15-18 of coal gangue, 15-18 of gypsum, 10-12 of fly ash, and 2-3 of sodium silicofluoride.

[0020] In any of the above schemes, it is preferred that in step (4), when the surface subsidence rate is fast or the accumulated subsidence amount is large, reinforcement grouting is performed through a grouting pipe to inject grouting material.

[0021] The beneficial effects of the present invention are:

[0022] 1. The method of the present invention is simple to construct and can effectively reduce the collapse angle and collapse height of the overburden rock by backfilling mining for non-typical key layers. The collapse angle is reduced by 33-35% and the collapse height is reduced by 80-82%. The lateral collapse and deformation of the coal-rock pillar are restricted, and the collapse space of adjacent working faces cannot be connected. The ground deformation and subsidence are reduced, and the ground deformation is less than level I, thereby improving the coal recovery rate, ensuring the safety of construction personnel, and improving the ecological environmental protection effect.

[0023] 2. In the present invention, the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is an important and key indicator that affects the mine pressure characteristics of the atypical key layer working face and the filling mining. By introducing the classification filling standard of the ratio of the thickness of the rock layer to the mining height of the lower coal seam and the filling grouting volume, an innovative construction process for filling mining of atypical key layers is proposed, which provides a new guiding basis for safe and efficient mining on site.

[0024] 3. The backfill mining method for non-typical key layers of the present invention can significantly alleviate mining stress concentration, and the backfill grouting material can effectively bear part of the load, reduce the peak load of the coal pillar, and effectively control the movement of the rock formation. DETAILED DESCRIPTION

[0025] The technical solution of the present application will be described in detail below in conjunction with the specific implementation methods of the present application, but the following examples are only for understanding the present invention. The embodiments in the present application and the features in the embodiments can be combined with each other, and the present application can be implemented in a variety of different ways as defined and covered by the claims.

[0026] Example 1

[0027] A non-typical key layer filling mining method for a coal mine comprises the following steps:

[0028] (1) Determine the backfill mining area and divide it into strips based on the requirements for surface subsidence control; first determine the thickness of the atypical key layer, and determine the backfill mining area based on the thickness of the atypical key layer. The backfill mining area is the area with a certain width expanded from the larger area of ​​the upper and lower coal seams;

[0029] (2) Strip mining is carried out in the filling mining area; when strip mining is carried out, the top of the surrounding rock of the goaf formed after strip mining is supported, and a lateral isolation support structure is set on the side of the goaf adjacent to the next mining strip;

[0030] (3) Grouting is performed to fill the goaf formed after strip mining, with the grouting volume being 35% of the mined coal volume; the grouting material is transported to the goaf formed after strip mining through the grouting pipe, and different grouting filling methods are used for the goaf according to the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam;

[0031] (4) While grouting the goaf of the mined strip, mining is carried out in the adjacent strip; during this process, the subsidence of the surface of the filled mining area is continuously observed;

[0032] (5) Repeat steps (2) to (4) to eventually fill all the goafs formed after all strip mining, thus completing the backfill mining operation.

[0033] The method of the present invention reduces the occurrence of mining accidents and reduces the pressure of grouting materials; significantly reduces the filling volume, and greatly improves the safety of filling operations by setting support and lateral isolation support structures, and the filling support effect is significant.

[0034] In the step (1), the filling mining area is, when the thickness of the atypical key layer is less than 6m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 25m; when the thickness of the atypical key layer is 6-9m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 20m.

[0035] In the step (1), the surface subsidence control requirement is based on the surface maximum subsidence control requirement; subsidence observation lines are arranged on the surface, including a plurality of longitudinal survey lines located at the boundaries of each strip along the mining direction and transverse survey lines perpendicular thereto, and the number of longitudinal survey lines and transverse survey lines is the same.

[0036] In the step (2), the lateral isolation support structure is arranged along the moving direction of the goaf, and the goaf section height of the strip is 5 meters and the width is 8 meters.

[0037] In step (2), the support strength of the top of the surrounding rock is determined according to the allowable value of the settlement of the coal seam roof in the filling mining area, and the lateral isolation support structure is set according to the support strength of the top of the surrounding rock, the geological structure characteristics of the mining space, the flow and solidification bearing characteristics of the grouting material, and the pressure. The lateral isolation support structure can resist the maximum pressure of the grouting material.

[0038] In the step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is less than 3, the goaf formed after strip mining is grouting-filled three times, the grouting volume of the first filling is 1 / 3 of the total grouting volume, the grouting volume of the second filling is 2 / 5 of the total grouting volume, and the third filling is the remaining grouting volume.

[0039] In step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is greater than or equal to 3 and less than 5, the goaf formed after strip mining is grouting-filled twice, the grouting volume of the first filling is 1 / 2 of the total grouting volume, and the second filling is the remaining grouting volume.

[0040] In the step (3), when grouting filling is performed, the next grouting filling is performed after each grouting material is solidified, and the solidification time of the grouting material is 12 hours.

[0041] The water-cement ratio of the grouting material is 5:2, and the grouting material includes the following components in parts by weight: 60 parts of cement, 22 parts of bauxite, 20 parts of limestone, 15 parts of coal gangue, 18 parts of gypsum, 10 parts of fly ash, and 3 parts of sodium silicofluoride.

[0042] In the step (4), when the surface subsidence rate is fast or the accumulated subsidence amount is large, reinforcement grouting is performed through the grouting pipe to inject grouting material.

[0043] Example 2

[0044] A non-typical key layer filling mining method for a coal mine comprises the following steps:

[0045] (1) Determine the backfill mining area and divide it into strips based on the requirements for surface subsidence control; first determine the thickness of the atypical key layer, and determine the backfill mining area based on the thickness of the atypical key layer. The backfill mining area is the area with a certain width expanded from the larger area of ​​the upper and lower coal seams;

[0046] (2) Strip mining is carried out in the filling mining area; when strip mining is carried out, the top of the surrounding rock of the goaf formed after strip mining is supported, and a lateral isolation support structure is set on the side of the goaf adjacent to the next mining strip;

[0047] (3) Grouting is performed to fill the goaf formed after strip mining, with the grouting volume being 38% of the mined coal volume; the grouting material is transported to the goaf formed after strip mining through the grouting pipe, and different grouting filling methods are used for the goaf according to the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam;

[0048] (4) While grouting the goaf of the mined strip, mining is carried out in the adjacent strip; during this process, the subsidence of the surface of the filled mining area is continuously observed;

[0049] (5) Repeat steps (2) to (4) to eventually fill all the goafs formed after all strip mining, thus completing the backfill mining operation.

[0050] In the step (1), the filling mining area is, when the thickness of the atypical key layer is less than 6m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 22m; when the thickness of the atypical key layer is 6-9m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 18m.

[0051] In the step (1), the surface subsidence control requirement is based on the surface maximum subsidence control requirement; subsidence observation lines are arranged on the surface, including a plurality of longitudinal survey lines located at the boundaries of each strip along the mining direction and transverse survey lines perpendicular thereto, and the number of longitudinal survey lines and transverse survey lines is the same.

[0052] In the step (2), the lateral isolation support structure is arranged along the moving direction of the goaf, and the goaf section height of the strip is 6 meters and the width is 7 meters.

[0053] In step (2), the support strength of the top of the surrounding rock is determined according to the allowable value of the settlement of the coal seam roof in the filling mining area, and the lateral isolation support structure is set according to the support strength of the top of the surrounding rock, the geological structure characteristics of the mining space, the flow and solidification bearing characteristics of the grouting material, and the pressure. The lateral isolation support structure can resist the maximum pressure of the grouting material.

[0054] In the step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is less than 3, the goaf formed after strip mining is grouting-filled three times, the grouting volume of the first filling is 1 / 3 of the total grouting volume, the grouting volume of the second filling is 2 / 5 of the total grouting volume, and the third filling is the remaining grouting volume.

[0055] In step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is greater than or equal to 3 and less than 5, the goaf formed after strip mining is grouting-filled twice, the grouting volume of the first filling is 1 / 2 of the total grouting volume, and the second filling is the remaining grouting volume.

[0056] In the step (3), when grouting filling is performed, the next grouting filling is performed after each grouting material is solidified, and the solidification time of the grouting material is 15 hours.

[0057] The water-cement ratio of the grouting material is 5:2, and the grouting material includes the following components in parts by weight: 50 parts of cement, 25 parts of bauxite, 15 parts of limestone, 18 parts of coal gangue, 15 parts of gypsum, 12 parts of fly ash, and 2 parts of sodium silicofluoride.

[0058] The grouting material of the invention can solidify quickly, expands in volume during the solidification process, and has high strength after solidification; the grouting material is non-toxic, harmless, and pollution-free, and has obvious environmental protection significance.

[0059] In the step (4), when the surface subsidence rate is fast or the accumulated subsidence amount is large, reinforcement grouting is performed through the grouting pipe to inject grouting material.

[0060] In addition, in order to further improve the technical effect of the present invention, in the embodiment, in the step (4), firstly, a hole is drilled to the uppermost complete rock layer below the lower coal seam to form a plurality of lower reinforcement grouting holes, and grouting materials are poured therein to form a lower grouting structure, and anchor bars are inserted into the lower reinforcement grouting holes, and the lower reinforcement structure is formed after the grouting materials solidify. Next, based on the observation results of the subsidence observation line, an oblique hole is drilled to the position of the atypical key layer to form a plurality of middle reinforcement grouting holes, and grouting materials are poured therein to form a middle grouting structure, and anchor bars are inserted into the middle reinforcement grouting holes, and the middle reinforcement structure is formed after the grouting materials solidify. Finally, a hole is drilled to a position 2m above the upper coal seam to form a plurality of upper reinforcement grouting holes, and grouting materials are poured therein to form an upper grouting structure, and anchor bars are inserted into the upper reinforcement grouting holes, and the upper reinforcement structure is formed after the grouting materials solidify.

[0061] The grouting material used for reinforcement grouting is the same as the grouting material used for previous grouting filling.

[0062] After grouting and filling, the present invention provides targeted reinforcement measures according to the real-time observed surface subsidence, which can significantly improve the supporting bearing strength of the atypical key layer and avoid the possible delayed subsidence of the formation, thereby achieving effective control of the formation structure, including the subsidence of the atypical key layer.

[0063] Example 3

[0064] A non-typical key layer filling mining method for a coal mine comprises the following steps:

[0065] (1) Determine the backfill mining area and divide it into strips based on the requirements for surface subsidence control; first determine the thickness of the atypical key layer, and determine the backfill mining area based on the thickness of the atypical key layer. The backfill mining area is the area with a certain width expanded from the larger area of ​​the upper and lower coal seams;

[0066] (2) Strip mining is carried out in the filling mining area; when strip mining is carried out, the top of the surrounding rock of the goaf formed after strip mining is supported, and a lateral isolation support structure is set on the side of the goaf adjacent to the next mining strip;

[0067] (3) Grouting is performed to fill the goaf formed after strip mining, with the grouting volume being 36% of the mined coal volume; the grouting material is transported to the goaf formed after strip mining through the grouting pipe, and different grouting filling methods are used for the goaf according to the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam;

[0068] (4) While grouting the goaf of the mined strip, mining is carried out in the adjacent strip; during this process, the subsidence of the surface of the filled mining area is continuously observed;

[0069] (5) Repeat steps (2) to (4) to eventually fill all the goafs formed after all strip mining, thus completing the backfill mining operation.

[0070] In the step (1), the filling mining area is, when the thickness of the atypical key layer is less than 6m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 24m; when the thickness of the atypical key layer is 6-9m, the larger area of ​​the upper and lower coal seams is used as the basis for the outward expansion width of 19m.

[0071] In the step (1), the surface subsidence control requirement is based on the surface maximum subsidence control requirement; subsidence observation lines are arranged on the surface, including a plurality of longitudinal survey lines located at the boundaries of each strip along the mining direction and transverse survey lines perpendicular thereto, and the number of longitudinal survey lines and transverse survey lines is the same.

[0072] In the step (2), the lateral isolation support structure is arranged along the travel direction of the goaf, and the goaf section height of the strip is 5.5 meters and the width is 7.5 meters.

[0073] In step (2), the support strength of the top of the surrounding rock is determined according to the allowable value of the settlement of the coal seam roof in the filling mining area, and the lateral isolation support structure is set according to the support strength of the top of the surrounding rock, the geological structure characteristics of the mining space, the flow and solidification bearing characteristics of the grouting material, and the pressure. The lateral isolation support structure can resist the maximum pressure of the grouting material.

[0074] In the step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is less than 3, the goaf formed after strip mining is grouting-filled three times, the grouting volume of the first filling is 1 / 3 of the total grouting volume, the grouting volume of the second filling is 2 / 5 of the total grouting volume, and the third filling is the remaining grouting volume.

[0075] In step (3), when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is greater than or equal to 3 and less than 5, the goaf formed after strip mining is grouting-filled twice, the grouting volume of the first filling is 1 / 2 of the total grouting volume, and the second filling is the remaining grouting volume.

[0076] The present invention can reasonably set the filling mining working face based on the surface subsidence control requirements, give full play to the technical advantages of the two types of processes, reduce the land resource damage and ecological environment deterioration caused by coal resource mining, and improve the coal resource recovery rate.

[0077] In the step (3), when grouting filling is performed, the next grouting filling is performed after each grouting material is solidified, and the solidification time of the grouting material is 13 hours.

[0078] The water-cement ratio of the grouting material is 5:2, and the grouting material includes the following components in parts by weight: 55 parts of cement, 23 parts of bauxite, 17 parts of limestone, 16 parts of coal gangue, 16 parts of gypsum, 11 parts of fly ash, and 3 parts of sodium silicofluoride.

[0079] In the step (4), when the surface subsidence rate is fast or the accumulated subsidence amount is large, reinforcement grouting is performed through the grouting pipe to inject grouting material.

[0080] The method of the present invention has high safety, good structural stability in the filling mining area, and after the goaf is filled, geological disasters such as floods, fires, gas, coal dust, and roof are significantly weakened or eliminated. The caving zone is eliminated, the fissure zone is greatly reduced, and the surface subsidence rate is low. The process of the present invention is simple, and can achieve maximum parallel operation, and adjacent operations have almost no impact on each other; the amount of filling auxiliary materials used is small, which saves a lot of material consumption and reduces the filling cost. The efficiency of construction is greatly improved, and the integrity of atypical key layers is good, which is conducive to the stratified mining of coal seams, the full development of underground coal resources, and the protection of the ecological environment and ground vegetation, and has significant economic and social benefits.

[0081] In addition, in order to further improve the technical effect of the present invention, in this embodiment, the lateral isolation support structure includes a top transverse support, a support column, a frame structure and a connection unit; the top transverse support and the frame structure are both made of I-beams, and the top transverse support can be provided with a certain bending elasticity; the support column adopts a prefabricated steel tube concrete structure, the frame structure is arranged below the top transverse support, and the frame structure and the top transverse support are arranged between adjacent support columns. A triangular support is arranged at the bottom of the support column, which is anchored in the bottom rock layer to maintain the stability of the support column, thereby providing an effective support effect for the overall lateral isolation support structure.

[0082] The top lateral support, adjacent support columns and frame structure are connected by a connection unit to form an integral lateral isolation support structure. The connection unit includes a bracket structure and fastening screws to improve the connection stability effect.

[0083] The frame structure is in the shape of a cross, and is hinged with the top lateral support and adjacent supporting columns by means of the connector at the end, and the degree of hinge is less than 30°.

[0084] A spacing unit is also arranged between the lateral isolation support structure and the side wall of the goaf. The spacing unit is a steel plate, a glass fiber reinforced plastic board is arranged on the side in contact with the side wall, and a waterproof resin is coated on the opposite side.

[0085] The lateral isolation support structure in this embodiment can have a certain deformation capacity when the force is too large, and can adjust the force, so as to avoid the overall structure from exceeding its bearing capacity and being damaged, thereby achieving effective support and improving the support strength of the goaf. It has a simple structure, is easy to process, manufacture and install, and is particularly suitable for support in atypical key layers.

[0086] The lateral isolation support structure in this embodiment has the effect of controlling the ground subsidence. On the basis of strengthening the internal filling material, support structures are added on both sides. In the early stage, a small range of sinking is allowed to achieve the purpose of pressure relief; in the later stage, it is strongly supported together with the internal filling material.

[0087] The lateral isolation support structure has good structural stability and corrosion resistance, and can effectively protect the contact between the filling material and the goaf environment, so that the filling material always maintains a high bearing capacity. Therefore, this structure has a greater advantage in maintaining long-term stability than traditional goaf filling bodies.

[0088] The lateral isolation support structure in this embodiment has a simpler construction process, a faster construction speed, and less impact on the mining efficiency of the coal mining face.

[0089] It can be seen from the above embodiments that the method of the present invention is simple to construct and can effectively reduce the collapse angle and collapse height of the overburden rock by backfilling mining for non-typical key layers. The collapse angle is reduced by 33-35% and the collapse height is reduced by 80-82%. The lateral collapse and deformation of the coal rock pillar are restricted, and the collapse space of adjacent working faces cannot be connected, thereby reducing ground deformation and subsidence. The ground deformation is less than level I, which improves the coal recovery rate, ensures the safety of construction personnel, and improves the ecological environment protection effect.

[0090] In the present invention, the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is an important and key indicator that affects the mine pressure characteristics of the atypical key layer working face and filling mining. By introducing the classification filling standard of the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam and the filling grouting amount, an innovative construction process for filling mining of atypical key layers is proposed, which provides a new guiding basis for safe and efficient mining on site.

[0091] The filling mining method for atypical key layers of the present invention can significantly alleviate mining stress concentration, and the filling grouting material can effectively bear part of the load, reduce the peak load of the coal pillar, and effectively control the movement of the rock layer.

[0092] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A non-typical key layer filling mining method for coal mines, It is characterized in that The following steps are involved: (1) Determine the filling mining area and divide it into strips based on the requirements for surface subsidence control; first determine the thickness of the atypical key layer, and determine the filling mining area based on the thickness of the atypical key layer. The filling mining area is that when the thickness of the atypical key layer is less than 6m, the larger area of ​​the upper and lower coal seams is used as the basis for the external expansion width of 22-25m; when the thickness of the atypical key layer is 6-9m, the larger area of ​​the upper and lower coal seams is used as the basis for the external expansion width of 18-20m; (2) Strip mining is carried out in the filling mining area; when strip mining is carried out, the top of the surrounding rock of the goaf formed after strip mining is supported, and a lateral isolation support structure is set on the side of the goaf adjacent to the next mining strip; (3) Grouting is performed on the goaf formed after strip mining, and the grouting volume is 35-38% of the volume of the mined coal; the grouting material is transported to the goaf formed after strip mining through the grouting pipe. When the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is less than 3, the goaf formed after strip mining is grouting three times; when the ratio of the thickness of the atypical key layer to the mining height of the lower coal seam is greater than or equal to 3 and less than 5, the goaf formed after strip mining is grouting twice; (4) While grouting the goaf of the mined strip, mining is carried out in the adjacent strip; during this process, the subsidence of the surface of the filled mining area is continuously observed; (5) Repeat steps (2) to (4) to eventually fill all the goafs formed after all strip mining, thus completing the backfill mining operation.

2. The non-typical key layer filling mining method of coal mine according to claim 1, It is characterized in that In step (1), the surface subsidence control requirement is based on the surface maximum subsidence control requirement; subsidence observation lines are arranged on the surface, including a plurality of longitudinal survey lines located at the boundaries of each strip along the mining direction and transverse survey lines perpendicular thereto, and the number of longitudinal survey lines and transverse survey lines is the same.

3. The non-typical key layer filling mining method of coal mine according to claim 2, It is characterized in that In step (2), the lateral isolation support structure is arranged along the travel direction of the goaf, and the goaf section height of the strip is 5-6 meters and the width is 7-8 meters.

4. The non-typical key layer filling mining method of coal mine according to claim 3, It is characterized in that In step (2), the support strength of the top of the surrounding rock is determined according to the allowable value of the settlement of the coal seam roof in the filling mining area, and the lateral isolation support structure is set according to the support strength of the top of the surrounding rock, the geological structure characteristics of the mining space, the flow and solidification bearing characteristics of the grouting material, and the pressure. The lateral isolation support structure can resist the maximum pressure of the grouting material.

5. The non-typical key layer filling mining method of coal mine according to claim 4, It is characterized in that In step (3), the grouting volume of the first filling is 1 / 3 of the total grouting volume, the grouting volume of the second filling is 2 / 5 of the total grouting volume, and the remaining grouting volume is filled in the third filling.

6. The non-typical key layer filling mining method of coal mine according to claim 5, It is characterized in that In step (3), the grouting volume of the first filling is 1 / 2 of the total grouting volume, and the remaining grouting volume of the second filling is.

7. The non-typical key layer filling mining method of coal mine according to claim 6, It is characterized in that In step (3), when grouting filling is performed, the next grouting filling is performed after each grouting material is solidified, and the solidification time of the grouting material is 12-15 hours.

8. The non-typical key layer filling mining method of coal mine according to claim 7, It is characterized in that The water-cement ratio of the grouting material is 5:2, and the grouting material includes the following components in parts by weight: 50-60 of cement, 22-25 of bauxite, 15-20 of limestone, 15-18 of coal gangue, 15-18 of gypsum, 10-12 of fly ash, and 2-3 of sodium silicofluoride.

9. The non-typical key layer filling mining method of coal mine according to claim 8, It is characterized in that In step (4), when the surface subsidence rate is fast or the accumulated subsidence volume is large, reinforcement grouting is performed through the grouting pipe to inject grouting material.