A method for controlling regional step-by-step support of a roadway under a goaf of an extremely close coal seam

Abstract

The application provides a kind of extremely close coal seam goaf under roadway regional step support control method, belong to coal mine underground mining technical field.The method includes: S1, the geological data and mining data of research area are analyzed and arranged;S2, the interval between lower coal seam roadway and upper goaf is detected, and the interval between extremely close coal seams is obtained Distribution characteristics and changes;S3, the drilling peep result is analyzed, and the drilling integrity index is obtained;S4, the segmented threshold and the corresponding stratum physical characteristics are determined;S5, the roof subsidence and roof pressure of different levels are analyzed;S6, the stress characteristics of I-beam support are analyzed;S7, the I-beam shed row distance range is calculated and a reasonable support scheme is developed.The application fully considers the damage characteristics of different interlayer strata caused by the mining of upper coal seam, and proposes a corresponding support scheme for the lower coal seam roadway according to the damage characteristics of different interlayer strata, which has wide application range, simple operation process and reliable evaluation result.

Description

Technical Field

[0001] This invention relates to the field of underground coal mining technology, and in particular to a method for regional cascade support control of roadways in coal seam goaf areas with extremely close proximity. Background Technology

[0002] With the increasing mechanization and mining intensity of coal mines in my country, coal seams with favorable geological conditions are becoming increasingly scarce in some mining areas. Coal seams with very close geological conditions are now being mined in major mining regions. When mining close-range coal seams, a downward mining method is often used. This can lead to roof instability and fracturing due to the movement of the upper coal seam during the mining of the lower seam. Furthermore, current technology cannot effectively control roof stability using the same support method for different seam spacings, creating safety hazards in the excavation and mining of the lower coal seam at very close distances.

[0003] Therefore, in order to ensure safe production in the mine during tunnel excavation, it is necessary to propose a control method that adopts corresponding support schemes for different layer spacings. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the cascade support of roadways in extremely close-range coal seam goaf areas. This method can analyze the variation characteristics of the interlayer spacing in the upper coal seam goaf area and the interlayer strata conditions under different interlayer spacings. By calibrating the interlayer spacing segment threshold, the support mode of the lower coal seam roadway under different interlayer spacings can be determined, thereby realizing risk classification and control, dynamic adaptation to geological changes and optimization of construction efficiency, and ensuring safe production in the mine.

[0005] To achieve the above objectives, this invention proposes a method for cascade support control in roadways of extremely close-range coal seam goaf areas, comprising the following steps:

[0006] S1. Analyze and organize the geological and mining data of the study area;

[0007] S2. Detect the interlayer spacing between the lower coal seam roadway and the upper goaf, analyze the detection results, and obtain the distribution characteristics and changes of the interlayer spacing of the very close coal seams.

[0008] S3. Conduct borehole inspection of the floor of the goaf of the upper working face in the lower coal seam roadway, analyze the borehole inspection results, calculate the integrity index (RMII) of each borehole, and classify the integrity of the borehole according to the integrity index evaluation level.

[0009] S4. Determine the interlayer spacing segment threshold based on the interlayer spacing evaluation level, and calculate the rock hardness coefficient (f) of the corresponding layer. n ) and rock layer stability coefficient (k) y );

[0010] S5. Analyze the characteristics of surrounding rock pressure, based on the segmented threshold of interlayer spacing and the rock layer hardness coefficient (f). n ) and rock layer stability coefficient (k) y Based on the actual geological parameters of the mine, the roof subsidence (b) and roof pressure (Q) were calculated respectively. H );

[0011] S6. Analyze the stress characteristics of the I-beam support and calculate the lateral bearing capacity (q) of the I-beam. x ) and the longitudinal bearing capacity (q) of the I-beam column y );

[0012] S7. Calculate the reasonable range (y) of the spacing between I-beam sheds and formulate a reasonable support plan.

[0013] Preferably, the geological and mining data in S1 include: Protodyakonov coefficient of rock mass, tensile strength of rock strata, roof thickness, unit weight of rock mass, roadway span, roadway depth, coal seam thickness, stress concentration factor of roadway sidewalls, internal friction angle of coal, dip angle of coal seam, maximum tensile stress of I-beam, elastic modulus of I-beam, and moment of inertia of I-beam.

[0014] Preferably, the specific formula for calculating the borehole integrity index (RMII) in S3 is as follows:

[0015]

[0016] In the formula: h1 and h2 are the given depths,

[0017]

[0018] In the formula: α is the influence coefficient of the complete block size effect of each rock mass.

[0019] Preferably, based on the calculation results of the borehole integrity index, the borehole integrity level is divided as follows: greater than 80% is excellent, 65% to 80% is good, 45% to 65% is average, 20% to 45% is poor, and less than 20% is extremely poor.

[0020] Preferably, the rock hardness coefficient (f) in S4 n The specific calculation formula is as follows:

[0021] f n =f i ×RMII×η

[0022] In the formula: f i η is the Protodyakonov coefficient for the intact rock mass, and η is the structural feature reduction coefficient, which is determined based on the structural surface conditions.

[0023] Preferably, in S4, under special rock mass fracturing conditions, the rock layer hardness coefficient (f) nDirectly using empirical values, that is:

[0024]

[0025] Preferably, the rock strata stability coefficient (k) in S4 y The specific calculation formula is as follows:

[0026]

[0027] In the formula: σ t γ is the tensile strength of the rock strata, kPa; t is the thickness of the top plate, m; γ is the unit weight of the rock mass, kg / m³. 3 L represents the tunnel span, in meters.

[0028] Preferably, the specific calculation formula for the top plate subsidence (b) in S5 is as follows:

[0029]

[0030] Top plate pressure (Q) H The specific calculation formula is as follows:

[0031] Q H =2γabB

[0032] In the formula: H is the tunnel depth, m; h is the coal seam thickness, m; a is the half-span of the tunnel, m; K is based on the rock properties measured in the laboratory and the geological report. cx γ is the stress concentration factor of the tunnel sidewall; γ is the average unit weight of the overlying strata, kg / m³. 3 B is a dimensionless parameter representing the degree of influence of mining; f y This refers to the hardness coefficient of coal. α is the internal friction angle of the coal; f is the dip angle of the coal seam; n k is the rock hardness coefficient. y This represents the rock stratum stability coefficient.

[0033] Preferably, the lateral bearing capacity (q) of the I-beam in S6 x The specific calculation formula is as follows:

[0034]

[0035] Longitudinal bearing capacity of I-beam supports (q) y The specific calculation formula is as follows:

[0036]

[0037] In the formula: σ is based on the mechanical properties of the I-beam measured in the laboratory. max The maximum tensile stress is calculated by taking the yield strength / tensile strength of the I-beam, and the result is the working load q of the I-beam.x / Ultimate load q x ′), MPa; W Z The section modulus of the I-beam is in meters. 3 l represents the clear span length of the I-beam, in meters; l1 represents the length of the I-beam support, in meters; E represents the elastic modulus of the I-beam, in Pa, based on the mechanical properties of the I-beam measured in the laboratory; I represents the moment of inertia of the I-beam, in meters. 4 μ is the length coefficient.

[0038] Preferably, the specific calculation formula for the reasonable range (y) of the I-beam spacing in S7 is as follows:

[0039] b1 <y<b2

[0040] in,

[0041]

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1. The method for regional cascade support control of roadways in coal seam goaf areas provided by this invention has a wide range of applications, simple operation process, reliable evaluation results, and parameters that can be quantitatively described;

[0044] 2. The method for regional tiered support control of roadways in extremely close-range coal seam goaf areas provided by this invention is highly reliable. It integrates field surveys, theoretical analysis, and field experiments, with field, theoretical, and field results mutually corroborating each other. It proposes to quantify the roof failure characteristics of roadways in extremely close-range coal seam goaf areas and determine segmented thresholds, enabling more accurate analysis of rock mass parameter variation characteristics in different areas. This allows for the proposal of optimal roadway support schemes for different areas, ensuring the reliability of the results while avoiding waste of roadway support materials. Furthermore, through extensive engineering practice, a corresponding database can be established to further optimize the research data results. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a flowchart of a method for regional cascade support control of roadways in extremely close coal seam goaf areas according to an embodiment of the present invention. Detailed Implementation

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] like Figure 1 As shown, the method for controlling the cascade support of the roadway in the goaf of a coal seam in this embodiment includes the following steps:

[0051] S1. Analyze and organize the geological and mining data of the study area, including but not limited to: Protodyakonov coefficient of rock mass, tensile strength of rock strata, roof thickness, unit weight of rock mass, roadway span, roadway burial depth, coal seam thickness, stress concentration coefficient of roadway sidewalls, internal friction angle of coal, dip angle of coal seam, maximum tensile stress of I-beams, elastic modulus of I-beams, and moment of inertia of I-beams.

[0052] In this embodiment, taking a coal mine as an example, the method for cascade support control of roadways in the goaf of a coal seam with extremely close proximity to the coal seam described in this application is explained in detail. This coal mine currently mainly mines coal seams #2 and #3. The thickness of coal seam #2 is 0.87-1.55m, with an average of 1.37m; its distance from coal seam #3 is 5.64-20.52m, with an average of 10.57m. The thickness of coal seam #3 is 0.90-1.84m, with an average of 1.57m. The average burial depth of the coal seams is 395m.

[0053] The intake airway of the 3210 working face, currently being excavated in the No. 3 coal seam, is located below the goaf of the 2210 working face, offset by 6 meters from the 2210 working face intake airway. The 3210 working face intake airway is excavated along the coal seam floor, with a designed length of 1014.7 meters, and is excavated with an opening angle of 163°. The airway is designed with a rectangular cross-section, with a width of 6000 mm and a height of 2800 mm. The excavation cross-sectional area is 14 m². 2 The net width is 4800mm, the net height is 2400mm, and the net cross-sectional area is 11.52m². 2 When the 3210 intake airway was excavated to the 810-meter mark, the distance between the roof and the upper 2210 goaf was only 2.6 meters.

[0054] S2. Detect the interlayer spacing between the lower coal seam roadway and the upper goaf, analyze the detection results, and obtain the distribution characteristics and changes of the interlayer spacing of the very close coal seams.

[0055] S3. Drill holes to inspect the floor of the goaf of the upper working face in the lower coal seam roadway, analyze the drilling inspection results, calculate the integrity index (RMII) of each borehole, and classify the integrity of the borehole according to the integrity index evaluation level.

[0056] The specific formula for calculating the borehole integrity index (RMII) is as follows:

[0057]

[0058] In the formula: h1 and h2 are the given depths,

[0059]

[0060] In the formula: α is the influence coefficient of the intact block size effect of each rock mass. The specific values ​​of α are shown in Table 1 below.

[0061] Table 1

[0062]

[0063] Based on the calculation results of the borehole integrity index, the borehole integrity level is divided as follows: greater than 80% is excellent, 65% to 80% is good, 45% to 65% is average, 20% to 45% is poor, and less than 20% is extremely poor.

[0064] Specifically, taking the aforementioned coal mine as an example, within a range of less than 5m between layers, boreholes were drilled every 0.5m to inspect the bottom plate of the goaf of the upper working face, for a total of 6 inspections. The integrity index (RMII) of each borehole and the evaluation level of borehole integrity are calculated as shown in Table 2 below.

[0065] Table 2

[0066]

[0067] S4. Determine the interlayer spacing segment threshold based on the interlayer spacing evaluation level, and calculate the rock hardness coefficient (f) of the corresponding layer. n ) and rock layer stability coefficient (k) y );

[0068] Among them, the rock hardness coefficient (f) n The average Protodactyl coefficients of different lithologies were selected for calculation, and the rock layer hardness coefficient (f) was calculated. n The specific calculation formula is as follows:

[0069] f n =f i ×RMII×η

[0070] In the formula: f i η is the Protodyakonov coefficient for the intact rock mass, and η is the structural feature reduction coefficient. The value of η is determined according to the structural surface conditions. The specific values ​​of η are shown in Table 3 below.

[0071] Table 3

[0072] Structural conditions η Rough, unweathered, closed, and unfilled 0.9～1.0 Slightly rough, hard filling 0.7～0.9 Smooth / muddy infill / active groundwater 0.4～0.6

[0073] Preferably, under special rock mass fracture conditions, the rock layer hardness coefficient (f) is... n Empirical values ​​can be used directly, that is:

[0074]

[0075] Rock stability coefficient (k) y The specific calculation formula is as follows:

[0076]

[0077] In the formula: σ t γ is the tensile strength of the rock strata, kPa; t is the thickness of the top plate, m; γ is the unit weight of the rock mass, kg / m³. 3 L represents the tunnel span, in meters.

[0078] Specifically, taking the aforementioned coal mine as an example, the interlayer spacing segment thresholds are determined based on the interlayer spacing evaluation level, and are 5.0m, 3.5m, and 2.6m respectively; based on the rock properties measured in the laboratory and the geological report, the Protodyakonov coefficient f of the intact rock mass is determined. i The thicknesses are 3.6 (5.0m), 4.1 (3.5m), and 3.9 (2.6m), respectively; the structural feature reduction coefficients η are 1.0 (5.0m), 0.9 (3.5m), and 0.8 (2.6m), respectively; the average tensile strength σ of the rock strata is... t The pressures are 846.72 kPa (5.0 m), 1209.60 kPa (3.5 m), and 1628.31 kPa (2.6 m), respectively; the average unit weight γ of the overlying strata is 24.5 kg / m³. 3 The tunnel span L is 6m.

[0079] Rock layer hardness coefficient (f) for calculating interlayer spacing segment threshold n ) and rock layer stability coefficient (k) y The calculation results are shown in Table 4.

[0080] Table 4

[0081] Segmented threshold / m <![CDATA[Rock hardness coefficient (f n )]]> <![CDATA[Rock formation stability coefficient (k y )]]> 5.0 2.9 6.4 3.5 2.5 3.2 2.6 1.7 1.2

[0082] S5. Analyze the characteristics of surrounding rock pressure, based on the segmented threshold of interlayer spacing and the rock layer hardness coefficient (f). n ), rock stratum stability coefficient (k) y Based on the actual geological parameters of the mine, the roof subsidence (b) and roof pressure (Q) were calculated respectively. H ).

[0083] The specific calculation formula for the roof settlement (b) is as follows:

[0084]

[0085] Top plate pressure (Q) H The specific calculation formula is as follows:

[0086] Q H =2γabB

[0087] In the formula: H is the tunnel depth, m; h is the coal seam thickness, m; a is the half-span of the tunnel, m; K is based on the rock properties measured in the laboratory and the geological report. cx γ is the stress concentration factor of the tunnel sidewall; γ is the average unit weight of the overlying strata, kg / m³. 3 B is a dimensionless parameter representing the degree of influence of mining; f y This refers to the hardness coefficient of coal. α is the internal friction angle of the coal; f is the dip angle of the coal seam; n k is the rock hardness coefficient.y This represents the rock stratum stability coefficient.

[0088] Specifically, taking the aforementioned coal mine as an example, the roadway burial depth H is 300m; the coal seam thickness h is 2.8m; the roadway half-span a is 3m; based on the rock properties measured in the laboratory and the geological report, the roadway side stress concentration factor K... cx The value is 1.5; the average unit weight γ of the overlying strata is 24.5 kg / m³. 3 The dimensionless parameter B for the degree of impact of mining is 1.2; the coal hardness coefficient f y The internal friction angle of coal is 2.2. The angle is 9°; the coal seam dip angle α is 4°. Substituting these parameters into the calculation yields the roof pressure (Q). H The calculation results are shown in Table 5.

[0089] Table 5

[0090] Segmentation threshold / (m) <![CDATA[Roof pressure (Q H ) / (KN / m)]]> 5.0 26.8 3.5 62.1 2.6 243.5

[0091] S6. Analyze the stress characteristics of the I-beam support and calculate the lateral bearing capacity (q) of the I-beam. x ) and the longitudinal bearing capacity (q) of the I-beam column y ).

[0092] Specifically, the I-beam support bears the pressure from the top slab in two ways: compressive stress along the longitudinal direction of the frame and bending moment in the vertical members. The support beams act as reaction supports for the canopy legs. Based on the tensile strength criterion and Euler's formula, the lateral bearing capacity (q) of the I-beam is calculated. x ) and the longitudinal bearing capacity (q) of the I-beam column y ), of which the lateral bearing capacity (q) of the I-beam. x The specific calculation formula is as follows:

[0093]

[0094] Longitudinal bearing capacity of I-beam supports (q) y The specific calculation formula is as follows:

[0095]

[0096] In the formula: σ is based on the mechanical properties of the I-beam measured in the laboratory. max The maximum tensile stress is calculated by taking the yield strength / tensile strength of the I-beam, and the result is the working load q of the I-beam. x / Ultimate load q x ′), MPa; W Z The section modulus of the I-beam is in meters. 3l represents the clear span length of the I-beam, in meters; l1 represents the length of the I-beam support, in meters; E represents the elastic modulus of the I-beam, in Pa, based on the mechanical properties of the I-beam measured in the laboratory; I represents the moment of inertia of the I-beam, in meters. 4 μ is the length coefficient.

[0097] Specifically, taking the aforementioned coal mine as an example, the maximum tensile stress σ max The value is 446 / 529 MPa, and the section modulus W of the I-beam is... Z It is 113.4m 3 The clear span length l of the I-beam is 4.36m, the length l1 of the I-beam support is 2.73m, the elastic modulus E of the I-beam is 200GPa, and the moment of inertia I of the I-beam is 127.7cm. 4 (Longitudinal), with a length coefficient μ of 1; the working load / ultimate load (q) of the lateral bearing capacity of the I-beams used in the coal mine is calculated. x / q x The longitudinal bearing capacity (q) of the I-beam column is 21.3 / 25.2 KN / m. y The critical load is 337.9 kN.

[0098] Specifically, the lateral bearing capacity (q) of the I-beam x ) and the longitudinal bearing capacity (q) of the I-beam column y After calculation, the minimum value is selected for subsequent calculations. Under normal circumstances, the lateral load that an I-beam can withstand is much smaller than the longitudinal critical load of an I-beam column. Here, the longitudinal bearing capacity (q) of the I-beam column is calculated. y It is mainly used for testing.

[0099] S7. Calculate the reasonable range (y) of the spacing between I-beam sheds and formulate a reasonable support plan.

[0100] The specific calculation formula for the reasonable range (y) of the spacing between I-beam sheds is as follows:

[0101] b1 <y<b2

[0102] in,

[0103]

[0104] Specifically, taking the aforementioned coal mine as an example, substituting the working load / ultimate load (q) of the I-beam... x / q x The reasonable range (y) of the I-beam shed spacing was calculated, and a reasonable support scheme was formulated based on the actual geological conditions of the mine, as shown in Table 6 below.

[0105] Table 6

[0106]

[0107] The method for regional tiered support control of roadways in extremely close-range coal seam goaf areas described in this application is highly reliable. It integrates field surveys, theoretical analysis, and field experiments, with on-site, theoretical, and field verification mutually reinforcing each other. It proposes to quantify the roof failure characteristics of roadways in extremely close-range coal seam goaf areas and determine segmented thresholds, enabling more accurate analysis of rock mass parameter variation characteristics in different areas. This allows for the proposal of optimal roadway support schemes for different areas, ensuring the reliability of the results while avoiding waste of roadway support materials. Furthermore, through extensive engineering practice, a corresponding database can be established to further optimize the research data results.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for regional cascade support control of roadways in coal seam goaf areas with extremely close proximity, characterized in that, Includes the following steps: S1. Analyze and organize the geological and mining data of the study area; S2. Detect the interlayer spacing between the lower coal seam roadway and the upper goaf, analyze the detection results, and obtain the distribution characteristics and changes of the interlayer spacing of the very close coal seams. S3. Conduct borehole inspection of the floor of the goaf of the upper working face in the lower coal seam roadway, analyze the borehole inspection results, calculate the integrity index (RMII) of each borehole, and classify the integrity of the borehole according to the integrity index evaluation level. S4. Determine the interlayer spacing segment threshold based on the interlayer spacing evaluation level, and calculate the rock hardness coefficient f for the corresponding layer. n and rock strata stability coefficient k y ; S5. Analyze the characteristics of surrounding rock pressure, based on the segmented threshold of interlayer spacing and the rock layer hardness coefficient f. n and rock strata stability coefficient k y Based on the actual geological parameters of the mine, the roof subsidence b and roof pressure Q were calculated respectively. H ; S6. Analyze the stress characteristics of the I-beam support and calculate the lateral bearing capacity q of the I-beam. x The longitudinal bearing capacity q of the I-beam support y ; S7. Calculate the reasonable range y of the spacing between I-beam sheds and formulate a reasonable support plan; The specific formula for calculating the borehole integrity index RMII in S3 is as follows: In the formula: h1 and h2 are the given depths, In the formula: α is the influence coefficient of the intact block size effect of each constituent rock mass; Rock hardness coefficient f in S4 n The specific calculation formula is as follows: f n =f i ×RMII×η In the formula: f i η is the Protodyakonov coefficient for intact rock mass, and η is the structural feature reduction factor, which is determined based on the structural surface conditions. Rock stability coefficient k in S4 y The specific calculation formula is as follows: In the formula: σ t γ is the tensile strength of the rock strata, kPa; t is the thickness of the top plate, m; γ is the unit weight of the rock mass, kg / m³. 3 L represents the tunnel span, in meters. The lateral bearing capacity q of the I-beam in S6 x The specific calculation formula is as follows: Longitudinal bearing capacity q of I-beam support y The specific calculation formula is as follows: In the formula: σ is based on the mechanical properties of the I-beam measured in the laboratory. max To determine the maximum tensile stress, the yield strength / tensile strength of the I-beam is used as the ratio, and the calculated result is the working load q of the I-beam. x / Ultimate load q x ′, MPa; W Z The section modulus of the I-beam is in meters. 3 l represents the clear span length of the I-beam, in meters; l1 represents the length of the I-beam support, in meters. Based on the mechanical properties of the I-beam measured in the laboratory, E is the elastic modulus of the I-beam, in Pa; I is the moment of inertia of the I-beam, in m. 4 μ is the length coefficient.

2. The method for regional cascade support control of roadways in extremely close-range coal seam goaf areas according to claim 1, characterized in that, The geological and mining data in S1 include: Protodyakonov coefficient of rock mass, tensile strength of rock strata, roof thickness, unit weight of rock mass, roadway span, roadway depth, coal seam thickness, stress concentration factor of roadway sidewalls, internal friction angle of coal, dip angle of coal seam, maximum tensile stress of I-beams, elastic modulus of I-beams, and moment of inertia of I-beams.

3. The method for regional cascade support control of roadways in extremely close-range coal seam goaf areas according to claim 1, characterized in that, Based on the calculation results of the borehole integrity index, the borehole integrity level is divided as follows: greater than 80% is excellent, 65% to 80% is good, 45% to 65% is average, 20% to 45% is poor, and less than 20% is extremely poor.

4. The method for regional cascade support control of roadways in extremely close-range coal seam goaf areas according to claim 1, characterized in that, In S4, under special rock mass fracture conditions, the rock layer hardness coefficient f n Directly using empirical values, that is:

5. The method for regional cascade support control of roadways in extremely close-range coal seam goaf areas according to claim 1, characterized in that, The specific calculation formula for the top plate settlement b in S5 is as follows: Top plate pressure Q H The specific calculation formula is as follows: Q H =2γabB In the formula: H is the tunnel depth, m; h is the coal seam thickness, m; a is the half-span of the tunnel, m; K is based on the rock properties measured in the laboratory and the geological report. cx γ is the stress concentration factor of the tunnel sidewall; γ is the average unit weight of the overlying strata, kg / m³. 3 B is a dimensionless parameter representing the degree of influence of mining; f y This refers to the hardness coefficient of coal. α is the internal friction angle of the coal; f is the dip angle of the coal seam; n k is the rock hardness coefficient. y This represents the rock stratum stability coefficient.

6. The method for regional cascade support control of roadways in extremely close-range coal seam goaf areas according to claim 1, characterized in that, The specific calculation formula for the reasonable range of I-beam spacing y in S7 is as follows: b1 <y<b2 in,

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