Filling mining method capable of filling while mining in rear of support and separation layer space

Abstract

The invention relates to a filling mining method with mining and filling in back-of-rack and separation space, which belongs to the technical field of coal mining and comprises the following steps: acquiring a distance H1 between the separation space and the ground, acquiring a distance H2 between the back-of-rack space and the separation space, vertically and downwards drilling a plurality of grouting holes with the depth of H1 + H2 in the ground along the tunneling direction of a working surface at equal intervals, according to the method, the grouting holes are drilled, the separation space is communicated with the space behind the support, the space behind the support is inserted into the grouting holes, grouting is conducted on the space behind the support through the space behind the support, and the separation space grouting pipe is arranged on the outer side of the space behind the support in a sleeving mode and inserted into the grouting holes for grouting till grouting is finished. After the working face is stoped, the space behind the support is firstly grouted and filled, after the separation layer space develops, the separation layer space is grouted and filled through the separation layer space grouting pipe, the mining cost is reduced, meanwhile, the grouting pressure can meet the requirements of different rock stratums, and therefore the effect of grouting and filling mining on ground surface deformation control is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a filling mining method for mining and filling the space behind a frame and in a separation layer as it is mined. Background Art

[0002] During the coal mining process, deformation and damage of the overlying rock strata above the goaf will cause problems such as steps, basins, and cracks on the surface. This will not only damage surface buildings, posing a major risk to engineering construction and the safety of human life and property, but will also cause groundwater infiltration, seriously affecting the ecological environment on the ground. In order to avoid the appearance of steps, basins, cracks and other problems on the surface, backfill mining technology is generally used, which can significantly control the subsidence and deformation of the surface and avoid deformation and damage to the overlying rock strata. In recent years, backfill mining technology has developed rapidly in coal mines, and can achieve safe mining of coal resources under buildings, water bodies and railways. Among them, overburden isolation grouting backfill mining is a type of backfill mining technology, which timely and effectively controls the deformation and collapse of the overburden strata by timely filling the overburden separation space.

[0003] Conventional grouting and backfilling of delaminations involves waiting for the working face to be mined, for the overburden to collapse, for the rock formation to deform, and for a delamination space to form beneath the critical stratum. Then, backfill material is injected into the delamination space through a surface borehole. This backfill material compacts the broken rock beneath the delamination space and creates a support zone, thereby supporting the critical stratum and controlling surface deformation. However, over time, the broken rock beneath the delamination space is prone to deformation, causing the surface to continue to deform at a later stage, resulting in poor results in controlling surface deformation through grouting and backfilling.

[0004] At present, in order to improve the effect of grouting and filling mining, the existing technology often uses the overburden separation grouting and subsidence reduction technology to grout the overburden collapse and rock deformation areas (behind-frame space, separation space) respectively, to avoid surface deformation in the later stage of grouting and filling mining. There are two ways to grout the behind-frame space: single-hole single separation grouting and single-hole mixed grouting. Among them, single-hole single separation grouting is to drill a hole from the ground to the behind-frame space and grout, and single-hole mixed grouting is to extend the grouting hole of the separation space to the behind-frame space for grouting. However, single-hole single separation grouting will increase the number of drilling holes, resulting in increased mining costs. Although single-hole mixed grouting can reduce mining costs as much as possible, due to the different pressures of different rock layers, and the pressure of single-hole mixed grouting is constant, it is difficult for the grouting pressure to take into account the needs of different rock layers, resulting in limited improvement in the effect of overburden separation grouting and subsidence reduction technology on controlling surface deformation. Summary of the Invention

[0005] In view of this, the present invention provides a filling mining method that can fill the space behind the frame and in the separated layers as it is mined, so as to solve the shortcomings of the existing technology. While reducing the mining cost, the present invention can also make the grouting pressure take into account the needs of different rock formations, thereby improving the effect of grouting filling mining on controlling surface deformation.

[0006] The technical solution of the present invention is: a backfill mining method for mining and filling the space behind the frame and the separation layer at the same time, comprising the following steps: Get the distance H1 between the layer space and the ground; Get the distance H2 between the space behind the rack and the space off the floor; Drill multiple grouting holes with a depth of H1+H2 at equal intervals vertically downward along the excavation direction of the working face on the ground. The grouting holes pass through the separation space and are connected to the space behind the frame. After the working face passes through the grouting hole, the grouting pipe of the space behind the frame is inserted into the grouting hole, and the lower end of the grouting pipe of the space behind the frame is extended into the space behind the frame. Grouting is performed into the space behind the frame using the grouting pipe of the space behind the frame. When the slurry is cemented with the gangue in the space behind the frame to form a complex, grouting into the space behind the frame is terminated. The grouting pipe for the delamination space is sleeved on the outside of the grouting pipe for the space behind the frame and inserted into the grouting hole. The lower end of the grouting pipe for the delamination space extends into the delamination space. The grouting pipe for the delamination space is used to perform grouting into the delamination space until completion.

[0007] Preferably, obtaining the distance H1 between the delamination space and the ground includes: obtaining the position of a key layer of the overlying stratum on the working face, and obtaining the distance H1 between the delamination space and the ground according to the position of the key layer.

[0008] Preferably, obtaining the key layer position of the overlying rock strata on the working face includes: calculating the load of each layer of rock beams above the coal seam on the first layer of rock beams layer by layer, until the load of the m+1th layer of rock beams on the first layer of rock beams is less than the load of the mth layer of rock beams on the first layer of rock beams, then the m+1th layer of rock beams is the key layer.

[0009] Preferably, the load of the mth rock beam on the first rock beam is obtained through the thickness, bulk density and elastic modulus of each rock layer from the first rock beam to the mth rock beam.

[0010] Preferably, the thickness, bulk density and elastic modulus of each rock layer are obtained by drilling vertically downward on the ground to obtain cores until the coal seam is reached, and then testing the physical and mechanical parameters of the obtained rock samples to obtain the thickness, bulk density and elastic modulus information of each rock layer.

[0011] Preferably, obtaining the distance H2 between the rear-shelf space and the off-layer space includes: Obtain the distance between the fracture zone and the coal seam according to the coal seam height and the distance between the collapse zone and the coal seam ; According to the distance between the fracture zone and the coal seam and the distance between the collapse zone and the coal seam The difference between the two is the distance H2 between the space behind the rack and the space on the floor.

[0012] Preferably, the distance between the first grouting hole and the working surface is 1 / 3 to 1 / 2 of the cut length, and the distance between adjacent grouting holes is the breaking distance of the grouting key layer.

[0013] Preferably, the breaking distance of the grouting key layer is obtained by the thickness of the rock layer, the load it bears and the tensile strength of the grouting key layer.

[0014] Preferably, if the pressure during grouting into the space behind the frame is greater than 5 MPa, the slurry will be cemented with the gangue in the space behind the frame to form a complex.

[0015] Preferably, grouting into the stratum space is terminated when the injected slurry volume reaches 35% to 50% of the coal production volume, the grouting pressure reaches 1.3 to 1.5 times the natural pressure of the formation, and the single-hole grouting volume is less than 50 t / d for three consecutive days.

[0016] Compared with the prior art, the present invention provides a filling mining method for the back-frame and detached space that is mined and filled as the back-frame and detached space are mined. By respectively obtaining the distance between the detached space and the ground and the distance between the back-frame space and the detached space, grouting holes are drilled to connect the detached space and the back-frame space. The back-frame space grouting pipe can be used to promptly grout the back-frame space after the working face is mined. Then, after the detached space is developed, the detached space grouting pipe is used to grout the detached space. While reducing the mining cost, the grouting pressure can also take into account the needs of different rock formations, thereby improving the effect of grouting filling mining on controlling surface deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of horizontal coal seam mining according to the present invention; Figure 2 This is a schematic diagram of grouting and filling the space behind the inclined coal seam frame of the present invention; Figure 3 This is a schematic diagram of grouting filling of the separated space of an inclined coal seam according to the present invention; Figure 4 It is a schematic diagram of the grouting pipe structure of the present invention; Figure 5 This is a schematic diagram of the grouting pipe for the abscission space of the present invention; Figure 6 It is a schematic diagram of the grouting pipe in the space behind the frame of the present invention.

[0018] Description of reference numerals: 2. Ablation space; 3. Space behind the frame; 4. Coal seam; 11. Grouting pipe for the abscission space; 12. Grouting pipe for the abscission space; 13. Grouting pipe outlet for the abscission space; 14. Grouting pipe outlet for the abscission space; 15. Grouting pipe valve for the abscission space; 16. Grouting pipe valve for the abscission space; 17. Pressure gauge for the grouting pipe for the abscission space; 18. Pressure gauge for the grouting pipe for the abscission space; 19. First inverted short joint; 110. Second inverted short joint; 111. Grouting section of the abscission space grouting pipe; 112. Slurry outlet of the abscission space grouting pipe. DETAILED DESCRIPTION

[0019] The present invention provides a filling mining method for mining and filling the space behind the frame and the separation layer as the mining progresses. Figures 1 to 6 The present invention is described with reference to a structural schematic diagram of FIG.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] like Figure 1 、 Figure 2 as well as Figure 3 As shown, a backfill mining method for back-of-frame and stratum space that is filled as it is mined comprises the following steps: Obtain the distance H1 between the layer space 2 and the ground; Obtain the distance H2 between the rear-shelf space 3 and the off-layer space 2; Multiple grouting holes with a depth of H1+H2 are drilled vertically downward at equal intervals along the excavation direction of the working face on the ground. The grouting holes pass through the separation space 2 and are connected to the space 3 behind the frame. After the working face passes through the grouting hole, the frame rear space grouting pipe 12 is inserted into the grouting hole, and the lower end of the frame rear space grouting pipe 12 extends into the frame rear space 3. Grouting is performed into the frame rear space 3 using the frame rear space grouting pipe 12. When the slurry is cemented with the gangue in the frame rear space 3 to form a complex, grouting into the frame rear space 3 is completed. The grouting pipe 11 for the delamination space is sleeved on the outside of the grouting pipe 12 for the space behind the frame and inserted into the grouting hole. The lower end of the grouting pipe 11 for the delamination space is extended into the delamination space 2. The grouting pipe 11 for the delamination space 2 is used to perform grouting into the delamination space 2 until the end.

[0022] The present embodiment provides a filling mining method for filling the space behind the frame and the delamination space as they are mined. By respectively obtaining the distance between the delamination space and the ground and the distance between the space behind the frame and the delamination space, and then drilling grouting holes to connect the delamination space and the space behind the frame, the grouting pipe of the space behind the frame can be used to promptly grout the space behind the frame after the working face is mined, and then after the delamination space is developed, the grouting pipe of the delamination space is used to grout the delamination space. While reducing the mining cost, the grouting pressure can also take into account the needs of different rock formations, thereby improving the effect of grouting filling mining on controlling surface deformation, and while further reducing surface subsidence, achieving the purpose of simplifying the process flow, reducing filling costs and timely filling the space behind the frame, thereby realizing green mining of the mine. The filling mining method of the present invention has good effect, low cost, strong practicality, and is worthy of promotion.

[0023] like Figure 4 As shown, in this embodiment, the upper end of the grouting pipe 11 of the delamination space is provided with a grouting pipe port 14 of the delamination space and a pressure gauge 18 of the delamination space grouting pipe. The grouting pipe port 14 of the delamination space is provided with a valve 16 of the delamination space grouting pipe. The grouting pipe port 14 of the delamination space is connected with the external grouting equipment through a pipeline to grout the delamination space 2 through the grouting pipe 11 of the delamination space. Figure 6 As shown, the upper end of the rear-frame space grouting pipe 12 is provided with a rear-frame space grouting pipe mouth 13 and a rear-frame space grouting pipe pressure gauge 17, and the rear-frame space grouting pipe mouth 13 is provided with a rear-frame space grouting pipe valve 15. The rear-frame space grouting pipe mouth 13 is connected with the external grouting equipment through a pipeline to grout the rear-frame space 3 through the rear-frame space grouting pipe 12.

[0024] In the above embodiment, the grouting effect is judged by observing the pressure conditions of the grouting pipe pressure gauge 18 of the separation layer space and the grouting pipe pressure gauge 17 of the space behind the frame, thereby further improving the accuracy of the grouting amount.

[0025] like Figure 5 As shown, in this embodiment, the lower end of the delamination space grouting pipe 11 is coaxially provided with a delamination space grouting pipe grouting section 111, one end of the delamination space grouting pipe grouting section 111 is connected to the delamination space grouting pipe 11, and the outer side of the delamination space grouting pipe 11 is radially provided with multiple delamination space grouting pipe slurry outlet holes 112 at equal intervals along its axial direction.

[0026] In this embodiment, a first inverted short section 19 is coaxially fixed to the lower end of the delamination space grouting pipe 11, and a second inverted short section 110 is coaxially fixed to the upper end of the delamination space grouting pipe grouting section 111. The first inverted short section 19 and the second inverted short section 110 are detachably fixedly connected.

[0027] In this embodiment, the first inverted short section 19 and the second inverted short section 110 are located 30m to 50m above the delamination space, wherein the first inverted short section 19 is designed with upper welding and lower threading, and the second inverted short section 110 is designed with upper threading and lower welding. The first inverted short section 19 and the second inverted short section 110 are threadedly connected. The length of the first inverted short section 19 and the second inverted short section 110 is 50cm. After being connected on the ground, they are inserted into the grouting hole along with the grouting pipe 11 in the delamination space.

[0028] The grouting materials in this embodiment include: Single fly ash grouting: water-ash mass ratio 1:1.5~2, slurry concentration 60%~75%; Composite material grouting: water-cement mass ratio is 1:1.2~1.5, and the composite material mass ratio is loess: stone powder: fly ash = 1:4:5; Gangue powder grouting: water-cement mass ratio is 1:1, slurry concentration is 50%~60%, and specific gravity is controlled at 1.3g / m3~1.4g / m3.

[0029] As a further optimization solution, obtaining the distance H1 between the delamination space 2 and the ground in this embodiment includes: obtaining the key layer position of the overlying rock stratum on the working face, and obtaining the distance H1 between the delamination space 2 and the ground according to the position of the key layer.

[0030] In this embodiment, after obtaining the key layer position of the overlying stratum on the working face, since the separation space 2 is located below the key layer, the distance between the bottom of the key layer and the ground is the distance H1 between the separation space 2 and the ground.

[0031] As a further optimization solution, this embodiment provides a method for obtaining the key layer position of the overlying rock strata on the working face, which includes: calculating the load of each layer of rock beams above the coal seam 4 on the first layer of rock beams layer by layer, until the load of the m+1 layer of rock beams on the first layer of rock beams is less than the load of the m layer of rock beams on the first layer of rock beams, then the m+1 layer of rock beams is the key layer.

[0032] As a further optimization solution, in this embodiment, the load of the mth rock beam on the first rock beam is obtained through the thickness, bulk density and elastic modulus of each rock layer from the first rock beam to the mth rock beam.

[0033] In this embodiment, the thickness, bulk density and elastic modulus of each rock layer are introduced into the following formula respectively: ; Where, is the load of the mth layer rock beam on the first layer rock beam, in kPa; is the thickness of the i-th rock beam, in m; is the bulk density of the i-th layer of rock beam, in MN / m 3 ; is the elastic modulus of the i-th rock beam, where i = 1, 2, …, m, and the unit is MPa.

[0034] According to the above embodiment, the load of the rock beam at the (m + 1)-th layer on the first layer is: ; In the formula, is the load of the rock beam at the (m + 1)-th layer on the first rock beam, and the unit is kPa; is the thickness of the i-th rock beam, and the unit is m; is the unit weight of the i-th rock beam, and the unit is MN / m 3 ; is the elastic modulus of the i-th rock beam (i = 1, 2, …, m), and the unit is MPa.

[0035] As a further optimization scheme, in this embodiment, the thickness, unit weight, and elastic modulus of each rock layer are obtained by vertically drilling cores downward on the ground until reaching the coal seam 4, and then testing the physical and mechanical parameters of the obtained rock samples, so as to obtain the thickness, unit weight, and elastic modulus information of each rock layer.

[0036] As a further optimization scheme, the distance H2 between the space 3 behind the support and the separated layer space 2 obtained in this embodiment includes: Obtaining the distance between the fractured zone and the coal seam respectively according to the coal seam height and the distance between the caving zone and the coal seam ; Obtaining the distance H2 between the space 3 behind the support and the separated layer space 2 according to the difference between the distance between the fractured zone and the coal seam and the distance between the caving zone and the coal seam .

[0037] The calculation method for obtaining the distance H2 between the space 3 behind the support and the separated layer space 2 in this embodiment is: ; In the formula, is the distance between the fractured zone and the coal seam, is the distance between the caving zone and the coal seam, and the unit is m; When the height M of the coal seam ≤ 3.5 m, , ; When the height 3.5 m < M < 6 m of the coal seam, , ; When the height M of the coal seam ≥ 6 m, , .

[0038] As a further optimization solution, in this embodiment, the distance between the first grouting hole and the working surface is 1 / 3 to 1 / 2 of the cut length, and the distance between adjacent grouting holes is the breaking distance of the grouting key layer.

[0039] In this embodiment, the distance between the first hole and the working face is set to 1 / 3 to 1 / 2 of the cutting length, which can enable the grouting hole to be located at the maximum separation space position below the key layer, thereby improving the grouting effect. The distance between adjacent grouting holes is set to the breaking distance of the grouting key layer, which can avoid the breaking of the grouting key layer and further control the surface subsidence.

[0040] As a further optimization solution, in this embodiment, the breaking distance of the grouting key layer is obtained by the rock thickness, the load it bears, and the tensile strength of the grouting key layer.

[0041] In this embodiment, the rock thickness, load and tensile strength of the key grouting layer are introduced into the following formula to calculate the breaking distance of the key grouting layer: ; Where, L is the breaking distance of the key grouting layer, in m; h is the thickness of the rock layer of the key grouting layer, in m; is the load borne by the key grouting layer, in kPa; R t It is the tensile strength of the key grouting layer, in MPa.

[0042] At the same time, in this embodiment, each grouting hole is drilled 50m ahead of the working surface.

[0043] In this embodiment, the grouting holes are drilled 50m ahead of the working face, so that the space behind the frame can be filled with grouting first after the grouting holes are pushed through the working face, thereby timely and effectively filling the collapsed space behind the frame after the working face is mined, without having to wait for the development of the detachment space before grouting can be carried out.

[0044] As a further optimization solution, in this embodiment, if the pressure during grouting into the space 3 behind the frame is greater than 5 MPa, the slurry will be cemented with the gangue in the space 3 behind the frame to form a composite body.

[0045] In this embodiment, when the pressure during grouting into the space 3 behind the frame is greater than 5 MPa, no more grout can be injected into the space 3 behind the frame. At this time, the overburden has fully collapsed, and grouting can be performed on the separation space.

[0046] As a further optimization scheme, in this embodiment, when the volume of injected slurry reaches 35% to 50% of the coal production volume, the grouting pressure reaches 1.3 to 1.5 times the natural pressure of the formation, and the single-hole grouting volume is less than 50t / d for three consecutive days, the grouting into the stratum space 2 is completed, and the coal production volume is the volume of a certain length of the coal seam directly below the grouting hole, and the length of the coal seam directly below each grouting hole is equal.

[0047] The above disclosure is only a preferred specific embodiment of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A backfill mining method for mining and filling the space behind the frame and the separation layer as the mining progresses, characterized in that: The following steps are involved: Obtain the distance H1 between the detached space (2) and the ground; Obtaining a distance H2 between the rear-shelf space (3) and the off-layer space (2); Drilling a plurality of grouting holes with a depth of H1+H2 vertically downward at equal intervals along the excavation direction of the working face on the ground, wherein the grouting holes pass through the separation space (2) and are connected to the space behind the frame (3); After the working surface is pushed through the grouting hole, the rear-frame space grouting pipe (12) is inserted into the grouting hole, the lower end of the rear-frame space grouting pipe (12) extends into the rear-frame space (3), and the rear-frame space grouting pipe (12) is used to perform grouting into the rear-frame space (3). When the slurry is cemented with the gangue in the rear-frame space (3) to form a complex, the grouting into the rear-frame space (3) is terminated; The abscission space grouting pipe (11) is sleeved on the outside of the rear-frame space grouting pipe (12) and inserted into the grouting hole. The lower end of the abscission space grouting pipe (11) extends into the abscission space (2). Grouting is performed into the abscission space (2) using the abscission space grouting pipe (11) until completion.

2. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 1 is characterized in that: The method of obtaining the distance H1 between the delamination space (2) and the ground comprises: obtaining the position of a key layer of the overlying stratum on the working surface, and obtaining the distance H1 between the delamination space (2) and the ground according to the position of the key layer.

3. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 2 is characterized in that: The method of obtaining the key layer position of the overlying rock layer on the working face comprises: calculating the load of each rock beam on the first rock beam above the coal seam (4) layer by layer, until the load of the rock beam on the first rock beam is less than the load of the rock beam on the first rock beam, and then the rock beam on the m+1 layer is the key layer.

4. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 3 is characterized in that: The load of the m-th rock beam on the first rock beam is obtained through the thickness, bulk density and elastic modulus of each rock layer from the first rock beam to the m-th rock beam.

5. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 4 is characterized in that: The thickness, bulk density and elastic modulus of each rock layer are obtained by drilling vertically downward on the ground to obtain cores until the coal seam (4) is reached, and then the physical and mechanical parameters of the obtained rock samples are tested to obtain the thickness, bulk density and elastic modulus information of each rock layer.

6. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 1 is characterized in that: The method of obtaining the distance H2 between the rear-shelf space (3) and the off-layer space (2) includes: Obtain the distance between the fracture zone and the coal seam according to the coal seam height and the distance between the collapse zone and the coal seam ; According to the distance between the fracture zone and the coal seam and the distance between the collapse zone and the coal seam The difference between the distance H2 between the rear-shelf space (3) and the off-layer space (2) is obtained.

7. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 1 is characterized in that: The distance between the first grouting hole and the working surface is 1 / 3 to 1 / 2 of the cut length, and the distance between adjacent grouting holes is the breaking distance of the grouting key layer.

8. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 7 is characterized in that: The breaking distance of the grouting key layer is obtained through the rock thickness, load and tensile strength of the grouting key layer.

9. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 1 is characterized in that: If the pressure during grouting into the space behind the frame (3) is greater than 5 MPa, the grout is cemented with the gangue in the space behind the frame (3) to form a complex.

10. The backfill mining method for mining and filling the space behind the frame and the separation layer according to claim 1 is characterized in that: When the volume of injected slurry reaches 35% to 50% of the coal production volume, the grouting pressure reaches 1.3 to 1.5 times the natural pressure of the formation, and the single-hole grouting volume is less than 50 t / d for three consecutive days, the grouting into the abscission space (2) is terminated.

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