A method for determining coal mine "filling-remaining" size and filling rate based on ground deformation index

Abstract

The application discloses a kind of coal mine " fills - leave " size and filling rate determination method based on surface deformation index, comprising the following steps: according to the structure characteristics of protected object and its protection requirement, determine the surface critical deformation index;According to surface critical deformation index and coal seam occurrence parameter, calculate the maximum allowable mining thickness of goaf;Based on Wilson two-zone constraint theory and surface non-sufficient mining principle, the width of filling surface and reserved coal pillar is measured and calculated respectively;According to the side protection effect of filling body, the width of filling surface and reserved coal pillar is adjusted;According to the maximum allowable mining thickness of goaf, coal pillar and filling surface width, determine the minimum filling rate of " fill - leave " mining.The application effectively solves the problem of one-sided emphasis on underground coal pillar and filling body stability in the prior art, and provides a calculation method of key parameters of " fill - leave " mining under the condition of surface deformation quantization index.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of goaf filling. Specifically, it is a method for determining the "filling-remaining" size and filling rate of a coal mine based on surface deformation indicators. BACKGROUND

[0002] As the main energy source in China, coal has a wide distribution and a large demand. The modernization of the coal industry has greatly increased the amount of coal mined, but has also been accompanied by various technical and environmental problems. In China's main coal-producing areas, especially in eastern mining areas, as coal resources are gradually depleted, the problem of "three-under" coal is becoming increasingly prominent. In particular, under the conditions of thick coal seams (coal thickness greater than 3.5m), surface movement and deformation are large, and buildings are prone to damage. How to ensure the coordinated development of resource development and human settlement and ecological environment protection has become an important technical problem that coal mining enterprises need to solve.

[0003] At present, the main methods for "three-under" coal mining in China are strip mining and filling mining. Strip mining, as a kind of partial mining, leaves a coal pillar to support the overburden and control surface movement and deformation, but has the disadvantage of low resource recovery rate. Filling mining achieves the effect of replacing coal pillars and reducing mining space by filling the goaf with filling bodies, but has the disadvantages of high cost and reliability that needs to be improved. "Filling-remaining" mining combines the technical advantages of strip mining and filling mining, improves the stress environment of the coal pillar and increases the overall support strength of the coal pillar by reasonably arranging the coal pillar and the filling face, and can achieve safe, efficient and high recovery rate mining. This technology not only ensures the recovery rate of underground resources, but also achieves the goal of protecting the surface human settlement and ecological environment.

[0004] Patent document CN113688462A discloses a strip goaf control filling key parameter design method, which fully plays the bearing performance of the remaining coal pillar. By comprehensively analyzing the actual geological mining conditions of the mine and the test results of the coal pillar mechanics experiment, the optimal filling treatment method and filling parameters matched for keeping the coal pillar stable for a long time are determined. However, the technical solution belongs to the post-treatment of the abandoned coal goaf, and the filling parameters are determined based on the stress state and stability of the coal pillar, without considering the control degree of the ground surface. Patent document CN102011611A discloses a strip filling method of high-water swelling material for controlling the movement and deformation of overlying strata. The method is based on the key layer theory, calculates the limit span and safety span of the key layer, and then determines the filling parameters. The key layer is a control layer of the movement and deformation of the overlying strata and the ground surface. The core of the technical method is to ensure that the key layer is not broken, so as to determine the most economical filling width and filling rate of the strip filling, thereby maximizing the production benefit. However, the strip filling method of the technical solution mainly controls the key layer to slow down the movement and deformation of the overlying strata and the ground surface, but the specific control degree cannot be quantitatively expressed, and it is difficult to achieve the optimal matching of the ground surface control and the underground engineering design.

[0005] The scientific and reasonable determination of the "filling-remaining" mining parameters is the key to guarantee the stability of the underground coal pillar and the good control effect of the ground surface. However, the current parameter determination methods are mainly based on the key layer theory or the bearing characteristics of the coal pillar and the filling body, and few of them consider the whole from the underground to the ground surface, so as to realize the coordination and unity of the target control and the engineering design. Therefore, it is necessary to design a determination method of the "filling-remaining" size and filling rate of the coal mine based on the ground surface deformation index. SUMMARY

[0006] Therefore, the technical problem to be solved by the present application is to provide a determination method of the "filling-remaining" size and filling rate of the coal mine based on the ground surface deformation index, which coordinates the whole of the ground surface control target and the underground engineering design, realizes the determination of the "filling-remaining" key parameters, and guarantees the use safety of the surface buildings and structures in the mining affected area.

[0007] To solve the above technical problems, the present application provides the following technical scheme:

[0008] A determination method of the "filling-remaining" size and filling rate of the coal mine based on the ground surface deformation index, comprising the following steps:

[0009] Step (1): determining the ground surface critical deformation index according to the structure characteristics and protection requirements of the protected object;

[0010] Step (2): calculating the maximum allowable mining thickness of the goaf according to the ground surface critical deformation index and the coal seam occurrence parameters;

[0011] Step (3): Based on the two-zone constraint theory of Wilson and the principle of surface insufficient mining, the width of the filling surface and the width of the coal pillar are calculated respectively;

[0012] Step (4): According to the side protection of the filling body, the width of the filling surface and the width of the coal pillar are adjusted to determine the final design width of the filling surface and the final width of the coal pillar;

[0013] Step (5): According to the maximum allowable mining thickness of the goaf, the width of the coal pillar and the width of the filling surface, the minimum filling rate of "filling-remaining" mining is determined.

[0014] The above method for determining the "filling-remaining" size and filling rate of coal mine based on surface deformation index, in step (1):

[0015] ① For high-rise buildings: the inclination deformation value i m is selected as the critical surface deformation index of damage level II;

[0016] ② For large-span continuous factory buildings: the curvature deformation value k m is selected as the critical surface deformation index of damage level III;

[0017] ③ For ordinary houses: the tensile deformation value ε m is selected as the critical surface deformation index of damage level II. At present, the structure type of mine area housing has changed greatly compared with the past (brick-wood / brick-concrete structure), and the critical surface deformation index can also be obtained through house damage simulation experiment.

[0018] The above method for determining the "filling-remaining" size and filling rate of coal mine based on surface deformation index, in step (2):

[0019] ① For high-rise buildings: the calculation formula of the maximum allowable mining thickness of the goaf is

[0020]

[0021] ② For large-span continuous factory buildings: the calculation formula of the maximum allowable mining thickness of the goaf is

[0022]

[0023] ③ For ordinary houses: the calculation formula of the maximum allowable mining thickness of the goaf is

[0024]

[0025] In the above formula, r is the main influence radius, n1 is the mining degree coefficient of the working face along the strike, n3 is the mining degree coefficient of the working face along the inclination; α is the coal seam inclination, q is the surface subsidence coefficient when the working face is fully mined; b is the horizontal movement coefficient. The maximum allowable mining thickness of the goaf can also be calculated by numerical simulation or an empirical model formula summarized by the target mining area.

[0026] The above method for determining the "filling-remaining" size and filling rate of the coal mine based on the surface deformation index, m m m and the calculation formula of r is:

[0027]

[0028] Among them,

[0029] In the above formula, H is the mining depth, M is the mining thickness, θ is the main influence angle, η is the surface subsidence rate when the working face is not fully mined; the value range of n1 and n3 is [0, 1], if the calculation result is greater than 1, take 1; D1 is the working face inclination length, D3 is the working face strike length, when multiple working faces are adjacent to mining, D1 and D3 are the cumulative length in the direction respectively; f is the overburden rock lithology coefficient: 0.9 for soft rock, 0.8 for medium-hard rock, and 0.7 for hard rock.

[0030] In step (3) of the above method for determining the "filling-remaining" size and filling rate of the coal mine based on the surface deformation index, the calculation formula of the coal pillar remaining width a1 is:

[0031]

[0032] In the formula, ρ r is the core area rate for maintaining the stability of the coal pillar, the value range is [0.65, 1); μ is the safety factor of the coal pillar, the value is 1.5-2.0;

[0033] The calculation formula of the filling surface width b1 is: b1=λH; in the formula, λ is the width-depth ratio of the non-full mining working face, the value is 0.1-0.3.

[0034] In step (4) of the above method for determining the "filling-remaining" size and filling rate of the coal mine based on the surface deformation index, the calculation formula of the adjustment value Δ of the filling surface width and the coal pillar remaining width is:

[0035]

[0036] In the formula, ρ is the filling body density; σ is the uniaxial compressive strength of the coal pillar, σ' is the triaxial compressive strength of the coal pillar; φ1 is the internal friction angle of the coal pillar, φ2 is the internal friction angle of the filling body; ​​

[0037] The calculation formula of the final design width a2 of the filling surface is a2=a1-Δ.

[0038] The calculation formula of the final width b2 of the coal pillar is b2=b1+Δ.

[0039] In the step (5) of the method for determining the coal mine "filling-remaining" size and filling rate based on the surface deformation index:

[0040] 1. When the inclination deformation value i is taken as the surface critical deformation index, the calculation formula of the minimum filling rate C0 of the "filling-remaining" mining is: m

[0041]

[0042] 2. When the curvature deformation value k is taken as the surface critical deformation index, the calculation formula of the minimum filling rate C0 of the "filling-remaining" mining is: m

[0043]

[0044] 3. When the tensile deformation value ε is taken as the surface critical deformation index, the calculation formula of the minimum filling rate C0 of the "filling-remaining" mining is: m

[0045]

[0046] In the above formula, k is the dilatancy coefficient of the coal body, and is taken as 1.05-1.4; and β is the compression rate of the filling body.

[0047] The technical scheme of the present application has the following beneficial technical effects:

[0048] The present application selects a reasonable target mine area building (structure) group surface critical deformation index, and determines the calculation method of the maximum allowed mining thickness of the goaf, the final design width of the filling surface and the final width of the remaining coal pillar, and finally determines the minimum filling rate of the "filling-remaining" mining according to the maximum allowed mining thickness of the goaf, the final design width of the filling surface and the final width of the remaining coal pillar. The method for determining the coal mine "filling-remaining" size and filling rate based on the surface deformation index can take into account the whole from the underground to the surface, realize the coordination and unity of the surface movement control and the underground coal mining design, effectively solve the problem of one-sidedly focusing on the stability of the underground coal pillar and the filling body in the prior art, and provide a calculation method of the key parameters of the "filling-remaining" mining under the condition of the surface deformation quantization index. The present application can provide a beneficial reference for the design and parameter determination of the mining working face under the mine area building (structure) group. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 ​​​The filling mining roof stratum subsidence schematic diagram in the embodiment of the present application;

[0050] Figure 2 The "filling-remaining" coal pillar stress condition schematic diagram in the embodiment of the present application;

[0051] Figure 3 The "filling-remaining" coal pillar spalling filling to the goaf in the embodiment of the present application. DETAILED DESCRIPTION

[0052] The method for determining the "filling-remaining" size and filling rate of the coal mine based on the surface deformation index in the embodiment includes the following steps:

[0053] Step 1: According to the structure characteristics and protection requirements of the protected object, the surface critical deformation index is determined.

[0054] According to the "Code for Coal Pillar Design and Coal Mining under Buildings, Water Bodies, Railways and Main Roadways", the damage grade of the brick-concrete structure building in the mining area is controlled in the range of I-IV, and the corresponding surface movement deformation value.

[0055]

[0056] According to the structure characteristics and protection requirements of the protected object, the surface inclination, curvature and horizontal deformation are comprehensively considered, the sensitive deformation of the target building (structure) group and the allowable deformation value are selected as the surface critical deformation index, for example:

[0057] (1) The high-rise building is most sensitive to the inclination deformation, and is easy to be damaged when reaching the II level, so the inclination deformation value i m of the II level is selected as the surface critical deformation index;

[0058] (2) The large-span factory building is relatively sensitive to the curvature deformation, and is severely damaged when reaching the III level, so the k m value of the corresponding damage level is selected as the surface critical deformation index;

[0059] (3) Most of the houses are sensitive to the tensile deformation, and the curvature deformation is the second, and it is ensured to be within the II level of damage, so the ε m value of the corresponding damage level is selected as the surface critical deformation index.

[0060] Step 2: According to the surface critical deformation index and the coal seam occurrence parameters, the maximum allowable mining thickness of the goaf is calculated.

[0061] In the mining subsidence science, the calculation relationship between the maximum surface movement deformation value and the coal seam occurrence parameters of the working face is:

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] wherein: W m is the maximum surface subsidence value; r is the main influence radius; b is the horizontal movement coefficient; H is the mining depth; θ is the main influence angle; M is the mining thickness of the coal seam; η is the surface subsidence rate when the working face is not fully mined; and α is the coal seam inclination. m is the maximum inclination value; k m is the maximum curvature value; ε m is the maximum horizontal deformation value.

[0068] The surface subsidence rate can be obtained according to the relationship between the working face strike and inclination size and the mining depth after determining the working face full mining degree, and according to the mining area surface subsidence coefficient.

[0069]

[0070] wherein: q is the surface subsidence coefficient when the working face is fully mined, which is the maximum value of the subsidence rate when fully mined, and is mainly related to the overburden rock properties; n1 and n3 are the mining degree coefficients of the working face along the strike and inclination, respectively, The value range is [0, 1], and if the calculation result is greater than 1, then 1 is taken; D1 and D3 are the working face inclination and strike length, respectively, and are the cumulative length in this direction when multiple working faces are adjacent mined; f is the overburden rock property coefficient, and the soft rock takes 0.9, the medium-hard rock takes 0.8, and the hard rock takes 0.7.

[0071] The target building group surface critical deformation index determined in step 1 is taken as the calculation amount, and is brought into equations (1)-(3) to calculate the maximum allowable mining thickness of the goaf.

[0072] ①High-rise building group (critical deformation index is i m ):

[0073]

[0074] ②Large-span continuous factory area (critical deformation index is k m ):

[0075]

[0076] ③General residential area (critical deformation index is ε m )

[0077]

[0078] Step 3: Based on the two-zone constraint theory of Wilson and the principle of surface insufficient mining, the width of the filling surface and the coal pillar is calculated respectively.

[0079] According to the research results and a large amount of practical experience of strip mining surface subsidence control, the calculation method of the width of the filling surface and the coal pillar is as follows:

[0080] (1) Based on the two-zone constraint theory of Wilson and combined with the actual geological and mining conditions of the mining area, the width of the coal pillar is calculated.

[0081]

[0082] In the formula, ρ r is the core area rate of the stable coal pillar, and the value range is [0.65, 1).

[0083] Preliminary calculation of the size of the coal pillar a1:

[0084] a1=μa (11)

[0085] In the formula, μ is the safety factor of the coal pillar, generally taken as 1.5-2.0.

[0086] (2) According to the principle of surface insufficient mining, the width of the strip filling surface b1 is preliminarily calculated.

[0087] b1=λH (12)

[0088] In the formula, λ is the width-depth ratio of the insufficient mining working face, generally taken as 0.1-0.3.

[0089] Step 4: According to the side protection effect of the filling body beside the coal pillar, the width of the filling surface and the coal pillar is adjusted.

[0090] Related research shows that the filling surface arranged beside the coal pillar not only can be used as a replacement space to reduce the moving space of the coal seam roof, but also can play a side protection effect on the coal pillar, improving the stress environment of the coal pillar. The two together form a column-filling combined body, which improves the overall support strength of the coal pillar. Therefore, due to the existence of the filling body, the coal pillar can be appropriately reduced based on the original design size during the "filling-preservation" mining, but the stability of the column-filling combined body still needs to be taken as the premise.

[0091] Based on the stability criterion of the column-filling combined body after the filling beside the column, the width of the coal pillar and the filling surface is adjusted Δ.

[0092]

[0093] In the formula, ρ is the density of the filling material; σ and σ' are the uniaxial and triaxial compressive strengths of the coal pillar, respectively, in MPa; φ1 and φ2 are the internal friction angles of the coal pillar and the filling material, respectively, in °; σ and φ can both be measured by mechanical experiments.

[0094] Adjust the initial dimensions of the coal pillar and the filling surface to determine the final design width of the coal pillar and the filling surface, as shown in the following formula.

[0095] a2=a1-Δ (14);

[0096] b2 = b1 + Δ (15);

[0097] Step 5: Determine the minimum filling rate for "fill-retain" mining based on the maximum allowable thickness of the goaf, the coal pillar, and the width of the filling face.

[0098] The subsidence of the roof in backfilled coal mining includes the following factors: the approach distance of the roof and floor before backfilling (U1), the under-contact distance of the backfill (U2), the compression of the backfill (U3), and the compression of loose coal on the floor (U4). The first three are the main factors. Figure 1 As shown. Therefore, the compositional relationship of the subsidence of the top strata can be expressed as:

[0099] U = U1 + U2 + U3 (16)

[0100] To reflect the characteristics of the backfill body itself during backfilling mining, the filling ratio C and compression ratio β of the backfill material are selected as calculation indicators, then: U1+U2=M-MC (17)

[0101] U3=Mβ (18)

[0102] Substitute equations (17) and (18) into equation (16) to calculate the subsidence of the roof strata (i.e., the distance between the top of the filling body and the roof of the coal seam after compression deformation).

[0103] U = M – MC(1-β) (19)

[0104] In the formula, β represents the compressibility of the filling material, which is mainly related to the physical properties of the filling material itself (strength, density, porosity, particle shape and size, etc.). Empirical values ​​for the compressibility of the filling material under different filling materials and filling processes are as follows:

[0105]

[0106] The maximum allowable thickness M of the goaf calculated according to steps 1 and 4. 允 Coal pillar a2 and backfill face size b2. After the backfill face is mined, the supporting pressure will concentrate at the coal pillars on both sides. The coal pillar portion not supported by the backfill body will be squeezed out under the supporting pressure and fill into the goaf on both sides, such as... Figure 2 and Figure 3The relationship between the maximum allowable mining thickness and the roof subsidence at this time can be expressed as:

[0107]

[0108] where k is the dilatancy coefficient of the coal body, generally taken as 1.05-1.4.

[0109] Simultaneous equations (7), (8), (9) and equations (19), (20) are used to calculate the minimum filling rate Co of the filling surface under different allowable deformation indexes.

[0110] The minimum filling rate Co of the filling surface is calculated by taking the inclination value as the critical deformation index.

[0111]

[0112] The minimum filling rate Co of the filling surface is calculated by taking the curvature value as the critical deformation index.

[0113]

[0114] The minimum filling rate Co of the filling surface is calculated by taking the horizontal deformation value as the critical deformation index.

[0115]

[0116] Obviously, the above examples are merely examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted and the changes or variations derived therefrom are still within the protection scope of the patent application claims.

Claims

1. A method for determining the "fill-void" size and filling rate of a coal mine based on ground deformation indicators, characterized in that, It comprises the following steps: Step (1): According to the structure characteristics and protection requirements of the protected object, determine the surface critical deformation index; Step (2): According to the surface critical deformation index and coal seam occurrence parameters, calculate the maximum allowable mining thickness of goaf; Step (3): Based on the Wilson two-zone constraint theory and the principle of surface insufficient mining, respectively measure the filling face width and coal pillar width; Step (4): According to the side protection effect of the filling body, adjust the filling face width and coal pillar width, and determine the final design width of the filling face and the final width of the coal pillar; Step (5): According to the maximum allowable mining thickness of goaf, coal pillar and filling face width, determine the minimum filling rate of "filling-remaining" mining; In step (1): ① For high-rise buildings: select the tilt deformation value of damage level II i m As the surface critical deformation index; For large-span factory building with continuous slab: curvature deformation value of damage level III is selected k m As the index of surface critical deformation; For ordinary civilian houses: select the tensile deformation value of damage level II ε m As the surface critical deformation index; In step (2): ① For high-rise buildings: the calculation formula of the maximum allowable mining thickness of goaf is: ； ② For large-span continuous factory buildings: the calculation formula of the maximum allowable mining thickness of goaf is: ； ③ For ordinary houses: the calculation formula of the maximum allowable mining thickness of goaf is: ； In the above formula, r is the main influence radius, n 1 is the working face along the strike of mining degree coefficient, n 3 is the working face along the tendency of mining degree coefficient; α is the coal seam inclination, q is the working face full mining surface subsidence coefficient; b is the horizontal movement coefficient; i m , k m , ε m and r the calculation formulas of which are respectively: ； ； ； ； wherein ; ; , ; In the above formula, H is the mining depth of the coal seam, M is the mining thickness of the coal seam, θ is the main influence angle, and η is the surface subsidence rate when the working face is not fully mined; n 1 and n 3 The value range of is [0, 1], and if the calculation result is greater than 1, it is taken as 1; D 1 is the length of the working face inclination, D 3 is the length of the working face strike, and when multiple working faces are adjacent to be mined, D 1 and D 3 is the cumulative length in the direction, respectively; f is the overburden rock lithology coefficient: 0.9 for soft rock, 0.8 for medium-hard rock, and 0.7 for hard rock; In step (3), the coal pillar setting width a 1 The calculation formula is: ； ； In the formula, ρ r The core area rate for keeping the coal pillar stable is [0.65, 1). μ The coal pillar safety factor is 1.5-2.

0. Filling face width b 1 The calculation formula is: ; In the formula, λ is the width-depth ratio of the insufficient mining working face, and the value is 0.1-0.3; In step (4), the calculation formula of the adjustment value Δ of the filling face width and the coal pillar width is: wherein, ρ is the density of the backfill; σ is the uniaxial compressive strength of the coal pillar, σ' is the triaxial compressive strength of the coal pillar; φ 1 is the internal friction angle of the coal pillar, φ 2 is the internal friction angle of the backfill; then the final design width of the packing surface a The calculation formula of 2 is: a 2= a 1-Δ; Final width of coal pillar b 2 The calculation formula is: b 2 = b 1 + Δ; In step (5): ① with the value of the inclined deformation i m The minimum filling rate of "filling-remaining" mining as the surface critical deformation index C The calculation formula is: ； ② with curvature deformation value k m As the surface critical deformation index, the minimum filling rate of "filling-remaining" mining C The calculation formula of 0 is: ； ③ with the tensile deformation value ε m The minimum filling rate of "filling-remaining" mining as a surface critical deformation index C The calculation formula of 0 is: ； In the above formula, k is the dilatancy coefficient of coal, taking 1.05-1.4; β is the compression rate of the filling body.

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