Design method of partitioned filling rate of fully mechanized coal mining face passing through goaf of underlying abandoned roadway

Abstract

The application discloses a kind of mined-out area partitioned filling rate design method of fully mechanized working face through underlying empty lane, first determine the spatial distribution characteristics of fully mechanized working face and underlying empty lane;According to the distance between underlying empty lane and working face floor, the area of working face mined-out area and empty lane along the tendency is divided;Establish the relationship equation of overburden rock caving zone height H and working face hydraulic support floor pressure σ, study the plastic damage degree of surrounding rock of underlying empty lane under different floor pressure σ, and determine the critical value range of overburden rock caving zone height H by inversion;The numerical simulation is further used to determine the design value of mined-out area partitioned filling rate.The method is simple and accurate, can realize the safe and efficient passing of fully mechanized working face through underlying empty lane, and ensure the health operation and maintenance of underlying lane, dispose mine solid waste products, green environmental protection, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of design of underground goafs, and particularly relates to a method for designing the goaf filling rate of underground goafs in fully mechanized mining faces. Background Technology

[0002] Due to disorderly mining and irrational roadway layout, a single working face often leaves behind a dozen or even dozens of empty roadways. The crisscrossing coal and rock roadways exacerbate the mining pressure issues at the working face, with surrounding rock deformation exhibiting strong disturbance, multi-zone characteristics, and structural diversity. This poses safety hazards to fully mechanized mining faces passing through these empty roadway clusters, affecting the safe and efficient recovery of coal resources. When a fully mechanized mining face passes through an underlying, extremely close empty roadway, the gravity of the caving strata and the weight of the supports themselves are combined and applied to the working face floor. If this force exceeds the strength of the rock strata between the working face floor and the empty roadway, damage to the surrounding rock of the empty roadway can potentially lead to a serious support failure, not only affecting production efficiency and causing severe damage to the underlying, extremely close empty roadway, but also significantly impacting the safe production of the working face. Currently, the support for working face empty roadways mostly uses timber stacks and anchor bolts (cables), but their control effect is poor and the results are relatively low. Therefore, how to ensure the safe and efficient passage of the working face through the underlying, extremely close empty roadway while maintaining the stability of the empty roadway has become a major challenge in this type of problem. Summary of the Invention

[0003] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides a method for designing the filling rate of goaf areas in fully mechanized mining faces with underpasses.

[0004] Technical solution: The invention provides a method for designing the goaf filling rate in a fully mechanized mining face passing through an underlying goaf, specifically including the following steps:

[0005] Step 1: Determine the spatial distribution characteristics of the fully mechanized mining face and the underlying goaf, wherein the spatial distribution characteristics include the distance range between the underlying goaf and the bottom plate of the mining face;

[0006] Step 2: Based on the distance range in Step 1, divide the goaf area and the empty roadway along the dip direction of the fully mechanized mining face into n goaf areas;

[0007] Step 3: For the i-th goaf area, establish the relationship equation between the height H of the overburden caving zone and the pressure σ of the hydraulic support bottom plate of the working face, and numerically simulate the degree of plastic damage to the underlying goaf surrounding rock under different bottom plate pressures σ, and invert the critical value of the height H of the overburden caving zone, i=1,2,…,n;

[0008] Step 4: Based on the spatial distribution characteristics of the underlying goaf, establish a numerical analysis model to study the height of the caving zone when the goaf is divided into different filling rates during the process of the fully mechanized mining face passing through the underlying goaf, so as to obtain the relationship between the filling rate of the goaf and the height of the overlying caving zone.

[0009] Step 5: Determine the filling rate of the i-th goaf zone based on the critical value of the overlying caving collapse zone height H and the relationship between the filling rate of the goaf zone and the overlying caving collapse zone height.

[0010] Furthermore, the spatial layout features in step 1 also include: the spatial angle of the underlying tunnel, the burial depth of the underlying tunnel, the cross-sectional shape, and the original support method.

[0011] Furthermore, in step 2, the goaf and the empty roadway are divided into regions along the dip using the following formula:

[0012]

[0013] Among them, h max Indicates the maximum distance h between the underlying tunnel and the working face floor. min This represents the minimum distance between the underlying goaf and the working face floor, where k is the distance coefficient between the working face goaf and the underlying goaf along the dip direction.

[0014] Furthermore, the relationship between the height H of the overburden caving zone and the pressure σ of the hydraulic support bottom plate in step 3 is shown in the following equation:

[0015]

[0016] Where σ represents the pressure on the hydraulic support base plate, G represents the gravity of the hydraulic support, and S 顶 S represents the area of ​​the top plate of the hydraulic support. 底 This represents the area of ​​the hydraulic support base plate, and γ is a coefficient.

[0017] Furthermore, the horizontal distance between the starting and ending points of the goaf filling in the fully mechanized mining face and the underlying goaf roadway is greater than 50m.

[0018] Beneficial effects: This invention ensures the safe passage of the working face through the underlying goaf, preventing support subsidence during the process, and also guarantees the stability of the underlying goaf. This design method is simple, easy to implement, and highly safe, providing a reference for the design of longwall mining faces passing through extremely close underlying goafs. It achieves safe and efficient passage through underlying goafs while preserving them. The invention also allows for zoned optimization of the filling rate during goaf passage, improving mining efficiency and further enriching the theory of backfilling mining. It has broad applicability. Attached Figure Description

[0019] Figure 1 This is a trend profile diagram of the process of passing through the extremely close distance empty tunnel in the present invention.

[0020] Figure 2 This is a cross-sectional view of the process of passing through the extremely close-range empty tunnel in the present invention.

[0021] Figure 3 This is a diagram showing the plasticity development rate and development cloud map of the surrounding rock in the goaf area at different collapse zone heights in Zone 1 of the present invention.

[0022] Figure 4 This is the curve showing the maximum value of the caving zone height H at different distances h from the coal seam floor according to the present invention.

[0023] Figure 5 This is a curve showing the relationship between the minimum spacing between the underground tunnel and the bottom plate and the design fullness rate in different zones of this invention.

[0024] In the diagram, 1. Goaf zone 1; 2. Goaf zone 2; 3. Goaf zone 3; 4. Goaf zone 4; 5. Coal seam; 6. Underlying goaf; 7. Support; 8. Goaf; 9. Collapse zone; 10. Distance h from goaf to coal seam; 11. Collapse zone height H. Detailed Implementation

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Based on the mine's geological data, coal seam 5 is determined to be buried at a depth of 200m, with a working face width of 200m. The underlying goaf 6 is a semi-circular arched roadway, located 2-10m from the coal seam floor. The goaf's cross-sectional shape is 6m long, 3m high, and has a radius of 3m. It is located below the floor in the diagonal direction of the working face. The coal seam mining height is 4m. The dip and strike profiles of the working face passing through the underlying goaf are shown below. Figure 1 As shown in Figure 2.

[0027] Based on the spatial distribution characteristics of the underlying goaf and the coal seam, with a distance of 10 between the underlying goaf and the coal seam, and the working face goaf area 8 and the underlying goaf along the dip, the number of goaf zones n is divided according to the following formula:

[0028]

[0029] Where: n—the number of areas divided along the dip of the working face goaf and underlying goaf, rounded to the nearest integer;

[0030] h max —Maximum distance between the underpass tunnel and the working face floor, in meters;

[0031] h min —Minimum distance between the underpass tunnel and the working face floor, in meters;

[0032] k—the distance coefficient between the working face goaf and the underlying goaf along the dip direction, generally taken as 1 to 2m.

[0033] In this embodiment, the distance between the underlying goaf and the coal seam is 2–10 m, and the maximum distance h between the underlying goaf and the working face floor is... max =10m and minimum distance h min =2m, the working face goaf and the empty roadway are divided into zones along the dip direction. Calculations show that each 2m segment is divided into four zones corresponding to the overlying goaf within the ranges of 2-4m, 4-6m, 6-8m, and 8-10m. Figure 1 The goaf area is divided into goaf area 1, goaf area 2, goaf area 3, and goaf area 4. Different filling rates are designed for each area. The horizontal distance between the filling section and the underlying goaf should be greater than 50m. Therefore, the design of continuous filling of the goaf area is carried out when the distance is 50m.

[0034] An equation relating the height 11 of the caving zone 9 to the pressure σ on the bottom plate of the hydraulic support 7 at the working face was established. Numerical simulation was used to study the degree of plastic failure of the underlying rock in the underground tunnel 6 under different bottom plate pressures σ, and the critical range of the caving zone height was determined.

[0035]

[0036] Where: σ—pressure on the base plate of the hydraulic support, MPa;

[0037] γ is typically taken as 2.5 MPa / 100 m;

[0038] H—Height of the landslide zone, in meters;

[0039] G—Gravity of the hydraulic support, taken as 1.1 × 10⁻⁶ 5 N;

[0040] S 顶 —The area of ​​the hydraulic support top plate is taken as 12.25m². 2 ;

[0041] S 底 —The area of ​​the hydraulic support base plate is taken as 6.13m². 2 .

[0042] For goaf zone 1, a numerical model of the goaf was established. Different floor pressures σ corresponding to different caving zone heights were applied to the top of the goaf at different distances h from the coal seam floor. The plastic development rate of the surrounding rock in the goaf was studied. The plastic development rate of the surrounding rock at different caving zone heights and the cloud map of the plastic zone development of the surrounding rock in the goaf when h is 2m are shown in the figure. Figure 3 As shown, based on the field protection requirement that the plastic development rate within 8m of the surrounding rock in the tunnel should be less than 25% (i.e., the ratio of the plastic zone area to the total area should be less than 25%), the caving zone height H < 8m was obtained. Using the same method, the caving zone heights for h = 4m, 6m, and 8m were studied. The curves showing the maximum caving zone height corresponding to different distances h from the coal seam floor are shown below. Figure 4 As shown, their maximum values ​​are 13m, 16m, and 18m, respectively.

[0043] Based on the test of the physical and mechanical parameters of coal and rock in the working face area, the physical and mechanical parameters of the coal and rock mass are obtained, as shown in Table 1. Using the numerical simulation method, a numerical analysis model of the fully-mechanized caving face and the underlying empty roadway is established. The model has a length × width × height of 200m × 200m × 76m. The horizontal displacement is restricted around the model, and the vertical displacement is restricted at the bottom. A uniform load of 4MPa equivalent to the self-weight of the overlying strata is applied at the top. The constitutive relationship adopts the Mohr-Coulomb model. The specific research plan is shown in Table 2. The height H' of the caving zone at different filling rates during the process of the fully-mechanized working face passing through the underlying empty roadway is studied to determine the design plan of the filling rate of the goaf partition when the working face passes through the underlying extremely-close empty roadway;

[0044] Table 1

[0045]

[0046]

[0047] Table 2

[0048] partition Distance from the floor of the empty alley Fullness rate Landslide Height Control Range #1 2～4m 90％、80％、70％、60％ <8m #2 4～6m 80％、70％、60％、50％ <13m #3 6～8m 70％、60％、50％、40％ <16m #4 8～10m 60％、50％、40％、30％ <18m

[0049] According to the numerical simulation results and the failure of the surrounding rock of the underlying empty roadway and the development height H' of the caving zone, H'<H, the curves of the minimum distance h between the underlying empty roadway and the floor corresponding to different filling rates in different partitions are as Figure 5 shown. According to the critical value of the height H of the overlying caving zone and the curve relationship between the filling rate of the goaf partition and the height of the overlying caving zone, the filling rate of the i-th goaf partition is determined.

[0050] Therefore, when the distance h between the empty roadway and the floor is 2 - 4m, 4 - 6m, 6 - 8m, 8 - 10m, the corresponding filling rates at the heights H of the overlying caving zone of 8m, 13m, 16m, 18m are selected as 90%, 80%, 65%, 40% respectively.

[0051] The design of the filling rate of the goaf partition for the entire fully-mechanized working face passing through the underlying extremely-close empty roadway is completed.

[0052] In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention does not further explain various possible combination methods.

Claims

1. A method for designing the goaf filling rate in a fully mechanized longwall mining face passing through an underlying goaf, characterized in that, Specifically, the steps include the following: Step 1: Determine the spatial distribution characteristics of the fully mechanized mining face and the underlying goaf, wherein the spatial distribution characteristics include the distance range between the underlying goaf and the bottom plate of the mining face; Step 2: Based on the distance range in Step 1, divide the goaf area and the empty roadway along the dip direction of the fully mechanized mining face into n goaf areas; Step 3: For the i-th goaf area, establish the relationship equation between the height H of the overburden caving zone and the pressure σ of the hydraulic support bottom plate of the working face, and numerically simulate the degree of plastic damage to the surrounding rock of the underlying goaf by different bottom plate pressures σ, and invert the critical value of the height H of the overburden caving zone, i=1,2,…,n; Step 4: Based on the spatial distribution characteristics of the underlying goaf, establish a numerical analysis model to study the height of the caving zone when the goaf is divided into different filling rates during the process of the fully mechanized mining face passing through the underlying goaf, so as to obtain the relationship between the filling rate of the goaf and the height of the overlying caving zone. Step 5: Determine the filling rate of the i-th goaf zone based on the critical value of the overlying caving collapse zone height H and the relationship between the filling rate of the goaf zone and the overlying caving collapse zone height. In step 2, the following formula is used to divide the goaf and the empty roadway along the dip direction: ； Among them, h max Indicates the maximum distance h between the underlying tunnel and the working face floor. min denoted by k, which represents the minimum distance between the underlying goaf and the working face floor, and k is the distance coefficient between the working face goaf and the underlying goaf along the dip direction. The equation relating the height H of the overlying caving zone and the pressure σ on the bottom plate of the hydraulic support at the working face in step 3 is shown below: ； in, G represents the pressure on the hydraulic support base plate, and G represents the weight of the hydraulic support. This indicates the area of ​​the top plate of the hydraulic support. This indicates the area of ​​the hydraulic support base plate. is a coefficient.

2. The method for designing the goaf filling rate of a fully mechanized mining face passing through an underlying goaf according to claim 1, characterized in that, The spatial layout features in step 1 also include: the spatial angle of the underlying tunnel, the burial depth of the underlying tunnel, the cross-sectional shape, and the original support method.

3. The method for designing the goaf filling rate of a fully mechanized mining face passing through an underlying goaf according to claim 1, characterized in that, The horizontal distance between the starting and ending points of the goaf filling in the fully mechanized mining face and the underlying goaf roadway is greater than 50 m.

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