A method for controlling the collapse of the "empty plate" structure along the goaf side

Abstract

The present invention relates to a method for controlling the collapse of a "void plate" structure along the side of a goaf, belonging to the technical field of pre-splitting and roof cutting for goaf-retaining lanes, and solves technical problems such as insufficient filling density along the goaf side of the goaf-retaining lanes, turbulent airflow, and abnormally prolonged roof movement cycles caused by delayed collapse of existing goaf roofs. The solution is: a method for controlling the collapse of a "void plate" structure along the side of a goaf, comprising the following steps: 1) obtaining parameters; 2) calculating the height of the cut roof, 3) calculating the loads borne by the immediate left roof section, the immediate middle roof section, and the immediate right roof section; and 4) calculating the critical weakening coefficient to achieve timely collapse of the roof. Compared with the existing technology, the present invention has the advantages of strong operability and the ability to achieve timely collapse of the goaf roof.

Description

Technical Field

[0001] The present invention belongs to the technical field of pre-splitting and top cutting of gob-side entry retention, and in particular relates to a method for controlling the collapse of a "gob plate" structure along a gob side. Background Art

[0002] During the advancement of the mining face, the roof of the goaf will exhibit an "OX"-shaped fracture pattern. This fracture pattern is caused by the presence of an "empty plate" structural support area at the end of the goaf, which is composed of the mining boundary, coal wall, and support. As a result, the roof at the end cannot collapse synchronously with the working face shift, but instead there is a certain lag interval.

[0003] This delayed collapse can lead to a series of problems, such as insufficient filling density along the goaf of gob-side entryways, which can affect airflow distribution within the gob, leading to turbulent airflow, impairing mine ventilation, and abnormally prolonging the roof movement cycle. In severe cases, it can even cause large-scale roof pressure, posing a significant threat to mine safety and production. However, there is a lack of systematic analytical models for the mechanical evolution of the "empty plate" structure at the end of the gob-side entryway, and the relevant control theory remains understudied. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology and solve the technical problems such as insufficient filling density on the goaf side, turbulent airflow, abnormal extension of the roof movement cycle, etc. caused by delayed collapse of the existing goaf roof, the present invention provides a collapse control method for the "empty plate" structure along the goaf side.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a method for controlling the collapse of a "void plate" structure along the side of a goaf, comprising the following steps:

[0007] 1) Get parameters:

[0008] Obtain the rock structure characteristics and mechanical properties parameters of the mining area through drilling exploration;

[0009] The rock strata in the mining area include the coal wall, the unmined area located on the right side of the coal wall from top to bottom, the mining face and the goaf. A gob-side entry roadway is provided between the coal wall and the goaf. The rock strata above the goaf are divided into the direct roof and the old roof from bottom to top.

[0010] 2) Calculate the cutting height:

[0011] The top cutting height is calculated based on the relationship between the top cutting height and the rock structure characteristics of the mining area;

[0012] 3) Calculate the loads on the left, middle and right sections of the direct roof:

[0013] The cutting height is divided into the weakening layer height and the bearing layer height;

[0014] If the pre-splitting roof cutting occurs in the immediate roof, the rock layer above the goaf is divided from bottom to top into the immediate roof bearing layer, the immediate roof weakened layer, the remaining immediate roof and the old roof. The stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated.

[0015] If the pre-cracked roof occurs in the immediate roof and the old roof, the rock layer above the goaf is divided from bottom to top into the immediate roof bearing layer, the immediate roof weakened layer, the old roof weakened layer and the old roof bearing layer, and the stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated;

[0016] 4) Calculate the critical weakening coefficient to achieve timely roof collapse:

[0017] The cantilever beam model is established by treating the direct roof as a cantilever beam. The height of the bearing layer and the height of the weakened layer are calculated by combining the cantilever beam formula and the load on the middle section of the direct roof.

[0018] The critical weakening coefficient is calculated based on the critical weakening coefficient = weakening layer height / bearing layer height. If the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient, the roof will collapse in time.

[0019] Furthermore, the rock structure characteristics of the mining area in step 1) include the thickness of the coal seam, the thickness of the immediate roof, the thickness of the old roof, the actual mining height, the amount of roof subsidence, the amount of floor heave, and the coefficient of crushing expansion.

[0020] Furthermore, the mechanical performance parameters of the mining area in step 1) include the bulk density of the immediate roof, the uniaxial tensile strength of the immediate roof, and the bulk density of the old roof.

[0021] Furthermore, the relationship between the top cutting height and the rock formation structural characteristics of the mining area in step 2) is calculated as follows: ,in is the cutting height, For actual mining height, is the roof subsidence, is the amount of swell, is the coefficient of expansion.

[0022] Furthermore, in step 3), if the pre-splitting top occurs at the direct top, the load on the left section of the direct top is ,in is the load on the left section directly above the top, is the elastic modulus of the direct top, is the height of the direct top, is the bulk density of the direct top, is the bulk density of the old top, is the height of the old roof, is the elastic modulus of the old top.

[0023] Furthermore, in step 3), if the pre-splitting and cutting occurs at the direct top, the load on the middle section of the direct top is ,in is the load on the middle section of the direct top, is the elastic modulus of the direct top, is the moment of inertia of the direct top when the pre-splitting top occurs at the direct top, ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the direct top bearing layer, is the height of the remaining direct top; is the elastic modulus of the old top, is the moment of inertia of the old top when the pre-splitting top occurs at the direct top, ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old roof; It is the sum of the weight of the direct top and the old top. ,in is the bulk density of the direct top, is the height of the direct top, is the bulk density of the old top, is the height of the old top, 、 、 Substituting the load on the middle section of the direct top when the pre-splitting top occurs in the direct top, we can get .

[0024] Furthermore, in step 3), if the pre-splitting and cutting of the roof occurs on the immediate roof, the load borne by the right section of the immediate roof is equal to the load borne by the left section of the immediate roof.

[0025] Furthermore, in step 3), if the pre-splitting and cutting occurs at the immediate top and the old top, the load on the middle section of the immediate top is ,in is the load on the middle section of the direct top, is the elastic modulus of the direct top, is the moment of inertia of the direct top when the pre-splitting top occurs at the direct top and the old top, ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the immediate top bearing layer; is the elastic modulus of the old top, is the inertia moment of the old top when the pre-splitting top occurs at the direct top and the old top, ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old top bearing layer; 、 、 Substituting the load on the middle section of the direct top when the pre-crack cutting occurs at the direct top and the old top, we can get .

[0026] The beneficial effects achieved by the present invention are as follows: the present invention regards the direct roof as a cantilever beam to establish a cantilever beam model, calculates the bearing layer height and the weakening layer height based on the cantilever beam formula and the load borne by the middle section of the direct roof, and thus calculates the critical weakening coefficient, and uses the critical weakening coefficient as a quantitative indicator to establish a pre-splitting and cutting roof collapse control method, which has strong operability in engineering practice; based on the pre-splitting and cutting roof collapse control method, the problem of delayed collapse of the goaf roof is solved, avoiding the problems of insufficient filling density on the goaf side, turbulent airflow, and abnormally extended roof movement cycle in the goaf-retaining lane along the goaf.

[0027] Compared with the existing technology, the present invention has the advantages of strong operability and timely collapse of the goaf roof. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the overall fracture of the goaf in the present invention;

[0029] Figure 2 This invention Figure 1 Schematic diagram of the middle II section before pre-splitting and topping;

[0030] Figure 3 This invention Figure 1 Schematic diagram of the middle II section after pre-splitting and topping;

[0031] Figure 4 It is a schematic diagram of the pre-splitting and cutting top occurring at the direct top in the present invention;

[0032] Figure 5 It is a schematic diagram of the pre-splitting and top cutting occurring at the immediate top and the old top in the present invention.

[0033] In the figure: 1. Coal wall; 2. Unmined area; 3. Mining face; 4. Goaf; 5. Gob-side tunnel; 6. Direct roof; 7. Old roof; 8. Pre-cracked roof; 9. Direct roof bearing layer; 10. Direct roof weakened layer; 11. Remaining direct roof; 12. Old roof weakened layer; 13. Old roof bearing layer; 14. Working face advancement direction; 15. Working face hydraulic support; 16. Non-collapsed area; 17. New fault line; 18. OX fracture; 19. Pre-cracked area; 20. Gas production tool. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the accompanying drawings and examples. Example 1

[0035] like Figures 1 to 5 As shown, 14 represents the working face advancement direction, 15 represents the working face hydraulic support, 16 represents the non-collapsed area, 17 represents the new fracture line, 18 represents the OX fracture, 19 represents the pre-splitting area, and 20 represents the gas production tool. During the advancement of the mining working face 3, the pre-splitting and top cutting 8 will cut off the stress transmission of the rock formation, forming a new fracture line 17, actively guiding the rock formation fracture line and changing the original OX fracture 18 in the goaf 4. This embodiment uses pre-splitting and top cutting to establish a collapse control method for the "empty plate" structure along the side of the goaf, including the following steps:

[0036] 1) Get parameters:

[0037] Obtain the rock structure characteristics and mechanical properties parameters of the mining area through drilling exploration;

[0038] The rock strata in the mining area include a coal wall 1, an unmined area 2 located on the right side of the coal wall 1 from top to bottom, a mining face 3, and a goaf 4. A goaf-side entry roadway 5 is provided between the coal wall 1 and the goaf 4. The rock strata above the goaf 4 are divided into a direct roof 6 and an old roof 7 from bottom to top.

[0039] The rock structure characteristics of the mining area include the thickness of the coal seam, the thickness of the immediate roof 6, the thickness of the old roof 7, the actual mining height, the amount of roof subsidence, the amount of floor heave, and the coefficient of crushing expansion; the mechanical performance parameters of the mining area include the bulk density of the immediate roof 6, the uniaxial tensile strength of the mudstone in the immediate roof 6, and the bulk density of the old roof 7;

[0040] In this embodiment, the average thickness of the coal seam is 0.8m, the immediate roof 6 is mudstone, the thickness of the immediate roof 6 is 5.23m, and the bulk density of the immediate roof 6 is 25kN / m 3 The uniaxial tensile strength of the direct top 6 is 1.38Mpa; the old top 7 is siltstone with mud-calcareous cementation. The thickness of the old top 7 is 6m and the bulk density of the old top 7 is 26kN / m 3 In this embodiment, the actual mining height is 1.2m, the roof subsidence is 0.06m, the bottom heave is 0.04m, and the expansion coefficient is 1.33.

[0041] 2) Calculate the cutting height:

[0042] When pre-splitting and cutting the top 8, it is necessary to ensure that the gangue of the collapsed roof of the goaf 4 completely fills the goaf. The cutting height is calculated based on the relationship between the cutting height and the rock structure characteristics of the mining area. The calculation formula for the relationship between the cutting height and the rock structure characteristics of the mining area is: ,in is the cutting height, For actual mining height, is the roof subsidence, is the amount of swell, is the coefficient of expansion. Substituting the data in this embodiment, we can get the cutting height .

[0043] 3) Calculate the loads on the left, middle and right sections of the direct roof:

[0044] The cutting height is divided into the weakening layer height and the bearing layer height;

[0045] In this embodiment, the pre-splitting and roof cutting 8 occurs in the immediate roof 6. The rock layer above the goaf 4 is divided from bottom to top into the immediate roof bearing layer 9, the immediate roof weakened layer 10, the remaining immediate roof 11 and the old roof 7. The stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated.

[0046] The pre-splitting and cutting top 8 occurs at the immediate roof 6. In addition to its own weight, the left section of the immediate roof is also subject to the load of the overlying rock strata. The load on the left section of the immediate roof is ,in is the load on the left section directly above the top, is the elastic modulus of direct top 6, is the height of the direct top 6, For the bulk density of direct top 6, is the bulk density of Laoding 7, is the height of the old top 7, is the elastic modulus of the old top 7;

[0047] The pre-splitting and cutting of the roof 8 occurs at the direct roof 6. In addition to its own weight, the middle section of the direct roof is also subject to the load of the overlying rock strata. Unlike the left section of the direct roof, the middle section of the direct roof loses the left and right restraints due to the pre-splitting and cutting of the roof 8, making it no longer able to withstand shear and bending moments. However, since the rock strata are combined together, the curvatures of the upper and lower layers must tend to be consistent. Based on the curvature coordination principle, the load equation is modified to obtain the load on the middle section of the direct roof: ,in is the load on the middle section of the direct top, is the elastic modulus of direct top 6, It is the moment of inertia of the direct roof 6 when the pre-splitting top 8 occurs. At this time, the bending moment is mainly provided by the direct roof bearing layer 9 and the remaining direct roof 11. ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the direct top bearing layer 9, is the height of the remaining direct top 11; is the elastic modulus of the old top 7, is the moment of inertia of the old top 7 when the pre-splitting top 8 occurs at the direct top 6, ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old top 7; It is the sum of the weight of the direct top 6 and the old top 7. ,in For the bulk density of direct top 6, is the height of the direct top 6, is the bulk density of Laoding 7, For the height of the old top 7, 、 、 Substituting the load on the middle section of the direct top when the pre-splitting top 8 occurs at the direct top 6, we can get ;

[0048] The pre-splitting top 8 occurs at the direct top 6, and the load on the right section of the direct top is equal to the load on the left section of the direct top;

[0049] 4) Calculate the critical weakening coefficient to achieve timely roof collapse:

[0050] The cantilever beam model is established by treating the direct roof 6 as a cantilever beam. The height of the bearing layer and the height of the weakened layer are calculated by combining the cantilever beam formula and the load on the middle section of the direct roof.

[0051] In this embodiment, the pre-splitting and cutting top 8 occurs in the immediate roof 6, which is mudstone with an elastic modulus of 8.6 GPa, and the old roof 7 is siltstone with an elastic modulus of 9.6 GPa. When the height is 10m, combine the cantilever beam formula and the load on the direct top middle section into the formula ,in is the uniaxial tensile strength of the direct top bearing layer 9, and we obtain {H}_{Z1}=\sqrt {\frac {246.6\left ( {{H}_{Z1}+1.9} \right )^{3}} {\left [ {8.6\left ( {{H}_{Z1}+1.9} \right )^{3}+2073} \right ]\times 1.38}} Use Matlab to solve and calculate The three solutions are: -8.81, -0.49, 2.07. At this time, the height of the direct top bearing layer 9 The height of the direct top weakened layer 10 is 2.07m. The height of the remaining direct top is 11 The calculated critical weakening coefficient is 0.61.

[0052] The critical weakening coefficient is calculated based on the formula: critical weakening coefficient = weakening layer height / bearing layer height. If the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient, the roof collapse is achieved in a timely manner. In this embodiment, if the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient of 0.61, the roof collapse is achieved in a timely manner.

[0053] Example 2

[0054] This embodiment uses pre-splitting and top cutting to establish a collapse control method for the "empty plate" structure along the goaf side, including the following steps:

[0055] 1) Obtain the rock structure characteristics and mechanical properties parameters of the mining area through drilling exploration;

[0056] The rock strata in the mining area include a coal wall 1, an unmined area 2 located on the right side of the coal wall 1 from top to bottom, a mining face 3, and a goaf 4. A goaf-side entry roadway 5 is provided between the coal wall 1 and the goaf 4. The rock strata above the goaf 4 are divided into a direct roof 6 and an old roof 7 from bottom to top.

[0057] The rock structure characteristics of the mining area include the thickness of the coal seam, the thickness of the immediate roof 6, the thickness of the old roof 7, the actual mining height, the roof subsidence, the floor heave, and the coefficient of crushing expansion; the mechanical performance parameters of the mining area include the bulk density of the immediate roof 6, the uniaxial strength of the mudstone in the immediate roof 6, and the bulk density of the old roof 7;

[0058] In this embodiment, the average thickness of the coal seam is 2.4m, the immediate roof 6 is mudstone, the thickness of the immediate roof 6 is 5.5m, and the bulk density of the immediate roof 6 is 25kN / m 3 The uniaxial tensile strength of the direct top 6 is 1.38Mpa; the old top 7 is siltstone with mud-calcareous cementation. The thickness of the old top 7 is 6m and the bulk density of the old top 7 is 26kN / m 3 In this embodiment, the actual mining height is 2.41m, the roof subsidence is 0.06m, the bottom heave is 0.04m, and the expansion coefficient is 1.33.

[0059] 2) Calculate the cutting height:

[0060] When pre-splitting and cutting the top 8, it is necessary to ensure that the gangue of the collapsed roof of the goaf 4 completely fills the goaf. The cutting height is calculated based on the relationship between the cutting height and the rock structure characteristics of the mining area. The calculation formula for the relationship between the cutting height and the rock structure characteristics of the mining area is: in is the cutting height, For actual mining height, is the roof subsidence, is the amount of swell, is the coefficient of expansion, and the cutting height can be obtained by substituting the data in this embodiment into .

[0061] 3) Calculate the loads on the left, middle and right sections of the direct top:

[0062] The cutting height is divided into the weakening layer height and the bearing layer height;

[0063] In this embodiment, the pre-splitting and roof cutting 8 occurs in the immediate roof 6 and the old roof 7. The rock layer above the goaf 4 is divided from bottom to top into the immediate roof bearing layer 9, the immediate roof weakened layer 10, the old roof weakened layer 12 and the old roof bearing layer 13. The stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated.

[0064] The pre-crack cutting 8 occurs between the immediate roof 6 and the old roof 7. The load on the middle section of the immediate roof is ,in is the load on the middle section of the direct top, is the elastic modulus of direct top 6, is the moment of inertia of the direct roof 6 when the pre-splitting top 8 occurs. At this time, the direct roof bearing layer 9 and the remaining direct roof 11 mainly provide the bending moment. At this time, the direct roof bearing layer 9 mainly provides the bending moment. ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the direct top bearing layer 9; is the elastic modulus of the old top 7, It is the inertia moment of the old roof 7 when the pre-splitting top 8 occurs in the direct roof 6. At this time, the bending moment is mainly provided by the old roof bearing layer 13. ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old top bearing layer 13; 、 、 Substituting the load on the middle section of the direct top when the pre-crack cutting occurs at the direct top 6 and the old top 7, we can get ;

[0065] 4) Calculate the critical weakening coefficient to achieve timely roof collapse:

[0066] The cantilever beam model is established by treating the direct roof 6 as a cantilever beam. The height of the bearing layer and the height of the weakened layer are calculated by combining the cantilever beam formula and the load on the middle section of the direct roof.

[0067] In this embodiment, the pre-crack cutting occurs in the immediate roof 6 and the old roof 7. The immediate roof 6 is mudstone with an elastic modulus of 8.6 GPa. The old roof 7 is siltstone with an elastic modulus of 9.6 GPa. When the height is 10m, combine the cantilever beam formula and the load on the direct top middle section into the formula ,in is the uniaxial tensile strength of the direct top bearing layer 9, and we obtain {H}_{Z1}=\sqrt {\frac {257.14\times {H}_{Z1}} {\left [ {8.6\times {H}_{Z1}+87.75} \right ]\times 1.38}} , use Matlab to solve and calculate The three solutions are: -4.83, 0.48, 4.35. At this time, the height of the direct top bearing layer 9 The height of the direct top weakening layer 10 is 4.35m The height of the old top weakened layer 12 is 1.15m The calculated critical weakening coefficient is 0.61.

[0068] The critical weakening coefficient is calculated based on the formula: critical weakening coefficient = weakening layer height / bearing layer height. If the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient, the roof collapse is achieved in a timely manner. In this embodiment, if the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient of 0.61, the roof collapse is achieved in a timely manner.

[0069] The present invention uses the critical weakening coefficient as a quantitative indicator to establish a pre-splitting and roof-cutting collapse control method. In engineering practice, it has strong operability and can achieve timely roof collapse, which is of great significance for ensuring mining safety and improving resource recovery rate.

[0070] The above describes the embodiments of the present invention in detail in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. The embodiments can still be changed within the scope of knowledge possessed by ordinary technicians in this field. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for controlling the collapse of a "void plate" structure along the side of a goaf, characterized by: The steps include: 1) Get parameters: Obtain the rock structure characteristics and mechanical properties parameters of the mining area through drilling exploration; The rock formations in the mining area include a coal wall (1), an unmined area (2) located on the right side of the coal wall (1) from top to bottom, a mining working face (3), and a goaf (4). A goaf-side entryway (5) is provided between the coal wall (1) and the goaf (4). The rock formations above the goaf (4) are divided into a direct roof (6) and an old roof (7) from bottom to top. 2) Calculate the cutting height: The top cutting height is calculated based on the relationship between the top cutting height and the rock structure characteristics of the mining area; 3) Calculate the loads on the left, middle and right sections of the direct roof: The cutting height is divided into the weakening layer height and the bearing layer height; If the pre-splitting and cutting roof (8) occurs at the immediate roof (6), the rock layer above the goaf (4) is divided from bottom to top into the immediate roof bearing layer (9), the immediate roof weakened layer (10), the remaining immediate roof (11) and the old roof (7), and the stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated; If the pre-splitting and cutting roof (8) occurs at the immediate roof (6) and the old roof (7), the rock layer above the goaf (4) is divided from bottom to top into the immediate roof bearing layer (9), the immediate roof weakened layer (10), the old roof weakened layer (12) and the old roof bearing layer (13), the stress conditions of the immediate roof left section, the immediate roof middle section and the immediate roof right section are analyzed, and the loads on the immediate roof left section, the immediate roof middle section and the immediate roof right section are calculated; 4) Calculate the critical weakening coefficient to achieve timely roof collapse: The direct roof (6) is regarded as a cantilever beam to establish a cantilever beam model, and the load on the middle section of the direct roof is combined with the cantilever beam formula to calculate the height of the bearing layer and the height of the weakened layer; The critical weakening coefficient is calculated based on the critical weakening coefficient = weakening layer height / bearing layer height. If the ratio of the actual weakening layer height to the actual bearing layer height is greater than the critical weakening coefficient, the roof will collapse in time.

2. A method for controlling the collapse of a "void plate" structure along the goaf side according to claim 1, characterized in that: The rock structure characteristics of the mining area in step 1) include the thickness of the coal seam, the thickness of the immediate roof (6), the thickness of the old roof (7), the actual mining height, the amount of roof subsidence, the amount of floor heave, and the coefficient of crushing expansion.

3. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 2, characterized in that: The mechanical property parameters of the mining area in step 1) include the bulk density of the immediate roof (6), the uniaxial tensile strength of the immediate roof (6), and the bulk density of the old roof (7).

4. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 3 is characterized in that: The calculation formula of the relationship between the top cutting height and the rock structure characteristics of the mining area in step 2) is: ,in is the cutting height, For actual mining height, is the roof subsidence, is the amount of swell, is the coefficient of expansion.

5. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 4 is characterized in that: In step 3), if the pre-splitting top (8) occurs at the direct top (6), the load on the left section of the direct top is ,in is the load on the left section directly above the top, is the elastic modulus of the direct top (6), is the height of the immediate top (6), is the bulk density of the direct top (6), is the bulk density of the old top (7), is the height of the old roof (7), is the elastic modulus of the old top (7).

6. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 4 is characterized in that: In step 3), if the pre-splitting top (8) occurs at the direct top (6), the load on the middle section of the direct top is ,in is the load on the middle section of the direct top, is the elastic modulus of the direct top (6), is the moment of inertia of the direct top (6) when the pre-splitting top (8) occurs at the direct top (6), ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the direct top bearing layer (9), is the height of the remaining direct top (11); is the elastic modulus of the old top (7), is the moment of inertia of the old top (7) when the pre-splitting top (8) occurs at the direct top (6), ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old top (7); is the sum of the weights of the direct top (6) and the old top (7), ,in is the bulk density of the direct top (6), is the height of the immediate top (6), is the bulk density of the old top (7), is the height of the old top (7), 、 、 Substituting the load on the middle section of the direct top when the pre-splitting top (8) occurs at the direct top (6), we can get .

7. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 4 is characterized in that: In the step 3), if the pre-splitting and cutting top (8) occurs at the direct top (6), the load on the right section of the direct top is equal to the load on the left section of the direct top.

8. The method for controlling the collapse of the "empty plate" structure along the goaf side according to claim 4 is characterized in that: In step 3), if the pre-splitting and cutting top (8) occurs between the immediate top (6) and the old top (7), the load on the middle section of the immediate top is ,in is the load on the middle section of the direct top, is the elastic modulus of the direct top (6), is the moment of inertia of the direct top (6) when the pre-splitting top (8) occurs at the direct top (6) and the old top (7), ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the direct top bearing layer (9); is the elastic modulus of the old top (7), is the moment of inertia of the old top (7) when the pre-splitting top (8) occurs between the direct top (6) and the old top (7), ,in The width of the empty plate of the cantilever beam model is 1m. is the height of the old top bearing layer (13); 、 、 Substituting the load on the middle section of the direct top when the pre-crack cutting top (8) occurs at the direct top (6) and the old top (7), we can get .

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