Method and system for designing roof cutting height of coal-pillar-free self-forming roadway mining

Abstract

The invention discloses a method and system for designing the roof cutting height of coal-pillar-free self-forming roadway mining, and belongs to the technical field of coal mining, and the method comprises the following steps: according to the size of a stope, the advancing length of a working face and the thickness of an overlying strata top plate, analyzing the crushing and expanding characteristics of roof cutting caving rock mass through numerical simulation and similar simulation tests; on the basis of the crushing and swelling characteristics of the roof-cutting caving rock mass, the crushing and swelling amount of caving gangue in the bilateral roof-cutting range is calculated; and when the actual mining amount reaches the collapsed gangue crushing and swelling amount, the mining height at the moment serves as the optimal roof cutting height. According to the method, the collapse thickness of the overlying strata can be increased, more broken and expanded gangues are generated, the goaf can be fully filled, the broken and expanded balance of the overlying strata is realized, and the broken and expanded gangues are utilized to compensate the coal seam mining space, slow down the deformation of the overlying strata and relieve the damage to the surface ecological environment.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a method and system for designing the top cutting height of coal pillar-free self-forming laneway mining. Background Art

[0002] At present, the commonly used method of coal mining in my country is the longwall mining 121 method. After the longwall mining face is mined, the overlying rock stratum roof is not easy to collapse. The thickness of the rock stratum after collapse is insufficient, and the goaf cannot be completely filled, resulting in deformation and breakage of the overlying rock stratum, causing serious surface settlement and deformation, especially shallow coal seams, which are prone to cause ecological problems such as surface settlement deformation, soil erosion, etc. Based on this, Academician He Manchao proposed a method of top-cutting and pressure-relieving coal-free self-forming laneway mining. By cutting the top to cut off the connection between the roadway roof and the goaf roof, the problem of the overlying roof not being easy to collapse is solved. However, the current design of the top-cutting height and top-cutting angle is not accurate enough. Summary of the invention

[0003] The present invention aims to solve the shortcomings of the prior art and proposes a method and system for designing the cutting top height of self-forming tunnel mining without coal pillars, which can increase the collapse thickness of the overburden rock, produce more broken and expanded gangue, and completely fill the goaf, thereby achieving the balance of overburden rock broken and expanded, and using the broken and expanded gangue to compensate for the coal seam mining space, slow down the deformation of the overburden rock strata, and alleviate the damage to the surface ecological environment.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for designing the top cutting height of coal pillar-free self-forming roadway mining comprises the following steps:

[0006] According to the size of the stope, the length of the working face and the thickness of the overburden roof, the expansion characteristics of the rock mass after the top collapse are analyzed through numerical simulation and similar simulation tests.

[0007] Based on the crushing and swelling characteristics of the top-cutting collapsed rock mass, the crushing and swelling amount of collapsed gangue within the top-cutting range on both sides is calculated;

[0008] When the actual mining volume reaches the amount of collapsed gangue and expansion, the mining height at this time is taken as the optimal top cutting height.

[0009] Preferably, the collapse expansion characteristics of the top-cut rock mass include: stress-strain relationship of the collapse rock mass, initial collapse expansion coefficient of the collapse rock mass and residual collapse expansion coefficient of the collapse rock mass;

[0010] The stress-strain relationship of the collapsed rock mass is:

[0011]

[0012] Among them, σ1 represents the vertical stress on the collapsed rock mass, E1 represents the initial elastic modulus of the rock mass, ε1 represents the axial strain of the collapsed rock mass when the stress is σ1, and ε m represents the maximum possible axial strain of the collapsed rock mass, σ c Indicates rock mass strength;

[0013] The calculation method of the initial expansion coefficient of the collapsed rock mass includes:

[0014]

[0015] Among them, K1 represents the initial expansion coefficient of the collapsed rock mass, t1 represents the initial expansion height of the collapsed rock mass, and t represents the initial height of the rock mass;

[0016] The calculation method of the residual expansion coefficient of the collapsed rock mass includes:

[0017]

[0018] Among them, K2 represents the residual expansion coefficient of collapsed rock mass, γ represents the average bulk density of overlying rock strata, and h represents the burial depth of coal seam / rock strata.

[0019] Preferably, the method for calculating the amount of broken and expanded rock in the double-sided cutting range includes:

[0020] Calculate the amount of rock expansion in the i-th layer:

[0021]

[0022] in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of the double-sided top cutting;

[0023] The overburden within the range of the double-sided top cutting is calculated to obtain the final amount of collapse and expansion of the gangue:

[0024]

[0025] Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

[0026] The present invention also provides a top cutting height design system for coal pillar-free self-forming roadway mining, the system applies any of the above methods, including: a crushing expansion characteristic analysis module, a crushing expansion amount calculation module and a top cutting height confirmation module;

[0027] The crushing and expansion characteristics analysis module analyzes the crushing and expansion characteristics of the top-cutting and collapsed rock mass through numerical simulation and similar simulation tests according to the size of the stope, the advancement length of the working face and the thickness of the overburden roof;

[0028] The crushing and expansion amount calculation module calculates the crushing and expansion amount of collapsed gangue within the double-side cutting range based on the crushing and expansion characteristics of the cutting top collapsed rock mass;

[0029] When the actual mining volume reaches the amount of collapsed gangue expansion, the top cutting height confirmation module uses the mining height at this time as the optimal top cutting height.

[0030] Preferably, the collapse expansion characteristics of the top-cut rock mass include: stress-strain relationship of the collapse rock mass, initial collapse expansion coefficient of the collapse rock mass and residual collapse expansion coefficient of the collapse rock mass;

[0031] The stress-strain relationship of the collapsed rock mass is:

[0032]

[0033] Among them, σ1 represents the vertical stress on the collapsed rock mass, E1 represents the initial elastic modulus of the rock mass, ε1 represents the axial strain of the collapsed rock mass when the stress is σ1, and ε m represents the maximum possible axial strain of the collapsed rock mass, σ c Indicates rock mass strength;

[0034] The calculation method of the initial expansion coefficient of the collapsed rock mass includes:

[0035]

[0036] Among them, K1 represents the initial expansion coefficient of the collapsed rock mass, t1 represents the initial expansion height of the collapsed rock mass, and t represents the initial height of the rock mass;

[0037] The calculation method of the residual expansion coefficient of the collapsed rock mass includes:

[0038]

[0039] Among them, K2 represents the residual expansion coefficient of collapsed rock mass, γ represents the average bulk density of overlying rock strata, and h represents the burial depth of coal seam / rock strata.

[0040] Preferably, the method for calculating the amount of broken and expanded rock in the double-sided cutting range includes:

[0041] Calculate the amount of rock expansion in the i-th layer:

[0042]

[0043] in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of the double-sided top cutting;

[0044] The overburden within the range of the double-sided top cutting is calculated to obtain the final amount of collapse and expansion of the gangue:

[0045]

[0046] Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention can increase the collapse thickness of the overburden rock, produce more crushed and expanded gangue, completely fill the goaf, achieve overburden rock crushing and expansion balance, use crushed and expanded gangue to compensate for coal seam mining space, slow down the deformation of the overburden rock strata, and alleviate the damage to the surface ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] Figure 1 A schematic diagram of a method flow of an embodiment of the present invention;

[0051] Figure 2 is a flowchart of a method according to an embodiment of the present invention;

[0052] Figure 3 It is a schematic diagram of a mechanical calculation model of overburden rock fragmentation expansion according to an embodiment of the present invention;

[0053] Figure 4 It is a schematic diagram of a mechanical calculation model for the crushing and expansion of overburden rocks in a thin coal seam cut according to an embodiment of the present invention;

[0054] Figure 5It is a schematic diagram of the mechanical calculation model of overburden rock expansion under complex conditions in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] Embodiment 1

[0058] In this embodiment, if Figure 1 , Figure 2 As shown, a method for designing the top cutting height of coal pillar-free self-forming lane mining includes the following steps:

[0059] S1. According to the size of the stope, the length of the working face advancement and the thickness of the overburden roof, the crushing and swelling characteristics of the top-cutting collapsed rock mass are analyzed through numerical simulation and similar simulation tests. The crushing and swelling characteristics of the top-cutting collapsed rock mass include: the stress-strain relationship of the collapsed rock mass, the initial crushing and swelling coefficient of the collapsed rock mass and the residual crushing and swelling coefficient of the collapsed rock mass.

[0060] In this embodiment, when the coal pillar-free self-forming tunnel mining is carried out by cutting the top to relieve pressure, the connection between the tunnel roof and the goaf roof is cut off by cutting the top. At this time, the overlying rock strata are more likely to collapse. The overall volume of the collapsed rock strata will become larger due to its crushing and swelling characteristics, which can partially fill the goaf, increase the collapsed thickness of the overlying rock, and produce more crushed and expanded gangue. In theory, the goaf can be completely filled, achieving the crushing and swelling balance of the overlying rock, and using the crushed and expanded gangue to compensate for the coal seam mining space and slow down the deformation of the overlying rock strata.

[0061] Based on the distribution of the overlying rock formations, the crushing and swelling characteristics of the collapsed waste rock of the overlying rock formations under different conditions are determined. Since different lithologies have very different mechanical properties, the crushing and swelling degree of collapsed waste rock is also different when the distribution of the overlying rock formations is different; when the lithology of the overlying rock formation is relatively hard, its crushing and swelling characteristics are small when it collapses. At this time, the force can be increased by appropriately increasing the cutting top height, thereby indirectly improving the crushing and swelling characteristics of collapsed waste rock; when the lithology of the overlying rock formation is relatively soft, its crushing and swelling characteristics are large when it collapses. At this time, the cutting top height can be appropriately reduced. In order to maximize the crushing and swelling degree of collapsed waste rock, the cutting top height is adjusted accordingly for different lithologies to maximize the crushing and swelling of collapsed waste rock. Common rock crushing and swelling coefficients are shown in Table 1.

[0062] Table 1

[0063]

[0064] According to the state of the collapsed and swollen rock mass, the rock mass's swell coefficient is divided into an initial swell coefficient and a residual swell coefficient. The swell coefficient when the rock mass initially collapses is called the initial swell coefficient, and the swell coefficient when the rock mass collapses and finally stabilizes is called the residual swell coefficient. The residual swell coefficient determines the filling of the goaf and the collapse state of the overburden. In this embodiment, based on the study of the deformation characteristics of the broken rock mass, the stress-strain relationship of the collapsed rock mass is:

[0065]

[0066] Among them, σ1 represents the vertical stress on the collapsed rock mass, in Pa; E1 represents the initial elastic modulus of the rock mass, in Pa; ε1 represents the axial strain of the collapsed rock mass when the stress is σ1; ε m Represents the maximum possible axial strain of the collapsed rock mass; σ c Indicates rock mass strength, unit is Pa.

[0067] The initial expansion coefficient of collapsed rock mass and the residual expansion coefficient of collapsed rock mass can be calculated as:

[0068]

[0069] Among them, t1 represents the initial crushing height of the collapsed rock mass, in m; t2 represents the residual crushing height of the collapsed rock mass, in m; t represents the initial height of the rock mass, in m; K1 represents the initial crushing coefficient of the collapsed rock mass; K2 represents the residual crushing coefficient of the collapsed rock mass.

[0070] The relationship between the stress-strain and the expansion coefficient of the rock mass can be calculated as:

[0071]

[0072] The vertical stress on the rock mass can be calculated according to the burial depth of the rock mass:

[0073] σ1=γh,

[0074] Among them, γ represents the average bulk density of the overlying rock layer of the rock mass, and the unit is kg / m 3 ; h represents the burial depth of coal seam / rock stratum, in meters.

[0075] According to the above formula, the calculation method of the residual expansion coefficient of collapsed rock mass can be obtained as follows:

[0076]

[0077] According to formula K2, the residual expansion coefficient of the rock mass is mainly related to the elastic modulus of the rock mass itself, the initial expansion coefficient and the burial depth. When the geological conditions are determined, the rock mass and the burial depth can be determined. Therefore, in order to increase the expansion coefficient and expansion amount of the rock mass, the top cutting can be used to increase the collapse height of the rock stratum, so that the rock stratum produces more expansion, which can better fill the mining space and reduce the damage to the overlying rock strata, thereby slowing down the surface deformation. More expansion can also support the side of the goaf of the tunnel, reduce the pressure on the tunnel roof, and improve the stability and safety of the tunnel.

[0078] S2. Based on the characteristics of rock mass expansion and collapse after top cutting, calculate the expansion and collapse volume of collapsed gangue within the range of top cutting on both sides.

[0079] In this embodiment, based on the distribution of overlying rock strata and the relationship between tunnel height and coal seam thickness, the cutting height of collapsed waste rock of overlying rock strata under different conditions is determined to increase the crushing and expansion amount of collapsed waste rock. Based on the relative position relationship between the tunnel and the coal thickness, the cutting height under different conditions is determined. The mechanical model for calculating the crushing and expansion amount is the same when using double-sided cutting and not using double-sided cutting, and the mechanical model of double-sided cutting is selected for calculation. In the calculation, it is assumed that the working face has been fully mined, the collapsed rock mass follows the stress-strain relationship of the broken rock mass, the rock mass is fully crushed and expanded, and because the double-sided cutting goaf is basically filled, there is no delamination between the rock strata, and the load of the overlying rock strata is completely transferred to the goaf. Its mechanical model is as follows: Figure 3 As shown. Under the influence of double-sided top cutting, the rock layer within the double-sided top cutting range completely collapses, and the calculation formula for the amount of crushing expansion is as follows:

[0080]

[0081] Among them, h represents the burial depth of coal seam / rock stratum, in m; y represents the top cutting height; l represents the top cutting depth, in m; θ represents the top cutting angle, in °.

[0082] Based on the relative position relationship between the roadway and the coal thickness, the top cutting height under different conditions is determined. When mining thin / ultra-thin coal seams, since the roadway height is higher than the coal seam thickness, a part of the roof has been cut off during the roadway formation process. However, the amount of debris and expansion caused by the collapse of this part of the roof is generally not enough to completely fill the goaf. Therefore, it is still necessary to use the double-side top cutting technology for top cutting. Its mechanical model is as follows: Figure 4 As shown, however, when calculating the amount of crushing and expansion, the top cutting part during the process of dividing the lanes needs to be calculated. Therefore, the calculation formula for the amount of crushing and expansion of thin / ultra-thin coal seams is:

[0083]

[0084] Among them, l1 represents the height of the tunnel above the coal seam.

[0085] For coal seams of different thicknesses, the space of the goaf is different after coal seam mining, and the collapse of the rock mass is different. Under the same other test conditions, sandstone collapses from different heights, and its initial expansion coefficient is distributed in 1.794~2.110. The expansion coefficient is greatly affected by the collapse height. Therefore, in the field engineering, it is necessary to consider the expansion of the rock formation under different coal seam thicknesses (mining heights). Here, the rock mass full collapse coefficient η is introduced. Combined with the field overburden collapse data, the actual rock formation expansion is calculated as follows:

[0086]

[0087] Among them, η represents the full collapse coefficient of rock mass, which is 0.7-1.0 for medium-thick and late coal seams, 0.4-0.7 for thin coal seams, and 0-0.4 for extremely thin coal seams.

[0088] According to the above formula, when the average bulk density of the on-site overburden is obtained, the required rock stratum expansion can be roughly calculated according to the mining height, so as to determine the parameters of the top cutting, which can provide a calculation basis for on-site engineering and is applicable to simple geological conditions. In order to make the model closer to the site and applicable to complex conditions, the following is established: Figure 5 The mechanical model shown is used to calculate the amount of crushing and expansion of each rock layer within the range of double-sided cutting top. For thin coal seams, the cutting top part of the tunnel can also be calculated according to this formula.

[0089] The methods for calculating the amount of broken and expanded rock in the double-sided cutting range include:

[0090] Based on the crushing and swelling characteristics of the collapsed waste rock of the overlying strata, the crushing and swelling coefficients of collapsed waste rock of different lithologies are different. Since the crushing and swelling coefficients of each lithology are different, the distribution of the overlying strata has a crucial influence on the crushing and swelling degree of the collapsed waste rock. According to the distribution of the overlying strata, the cutting height needs to be adjusted accordingly. The rock strata after the double-side cutting technology produces crushing and swelling, and the rock strata in this area are called crushing and swelling rock strata. At this time, the crushing and swelling amount of the i-th rock stratum within the double-side cutting range is:

[0091]

[0092]

[0093] According to the above two formulas, the amount of rock expansion in the i-th layer is obtained:

[0094]

[0095] in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, It represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of double-sided cutting top.

[0096] The overburden within the range of double-sided cutting is calculated to obtain the final amount of collapsed gangue expansion:

[0097]

[0098] Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

[0099] S3. When the actual mining volume reaches the amount of collapsed gangue and expansion, the mining height at this time will be taken as the optimal top cutting height.

[0100] Embodiment 2

[0101] In this embodiment, a top cutting height design system for self-forming tunnel mining without coal pillars includes: a crushing and expansion characteristic analysis module, a crushing and expansion amount calculation module and a top cutting height confirmation module.

[0102] The crushing and expansion characteristics analysis module analyzes the crushing and expansion characteristics of the top-cutting rock mass through numerical simulation and similar simulation tests according to the size of the stope, the length of the working face advancement and the thickness of the overburden roof. The crushing and expansion characteristics of the top-cutting rock mass include: the stress-strain relationship of the collapsed rock mass, the initial crushing and expansion coefficient of the collapsed rock mass and the residual crushing and expansion coefficient of the collapsed rock mass.

[0103] The stress-strain relationship of collapsed rock mass is:

[0104]

[0105] Among them, σ1 represents the vertical stress on the collapsed rock mass, E1 represents the initial elastic modulus of the rock mass, ε1 represents the axial strain of the collapsed rock mass when the stress is σ1, and ε m represents the maximum possible axial strain of the collapsed rock mass, σ c Indicates the strength of rock mass.

[0106] The calculation methods of the initial expansion coefficient of collapsed rock mass include:

[0107]

[0108] Among them, K1 represents the initial expansion coefficient of the collapsed rock mass, t1 represents the initial expansion height of the collapsed rock mass, and t represents the initial height of the rock mass.

[0109] The calculation methods of residual expansion coefficient of collapsed rock mass include:

[0110]

[0111] Among them, γ represents the average bulk density of the overlying rock strata, and h represents the burial depth of the coal seam / rock strata.

[0112] The crushing and expansion amount calculation module calculates the crushing and expansion amount of collapsed waste rock within the double-sided cutting range based on the crushing and expansion characteristics of the top-cutting collapsed rock mass. The method for calculating the crushing and expansion amount of collapsed waste rock within the double-sided cutting range includes:

[0113] Calculate the amount of rock expansion in the i-th layer:

[0114]

[0115] in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, It represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of double-sided cutting top.

[0116] The overburden within the range of double-sided cutting is calculated to obtain the final amount of collapsed gangue expansion:

[0117]

[0118] Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

[0119] When the actual mining volume reaches the amount of collapsed gangue and expansion, the top cutting height confirmation module takes the mining height at that time as the optimal top cutting height.

[0120] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for designing the top cutting height of coal pillar-free self-forming roadway mining, characterized in that: The following steps are involved: According to the size of the stope, the length of the working face advancement and the thickness of the overburden roof, the crushing and swelling characteristics of the top-cutting collapsed rock mass are analyzed through numerical simulation and similar simulation tests. The crushing and swelling characteristics of the top-cutting collapsed rock mass include: the stress-strain relationship of the collapsed rock mass, the initial crushing and swelling coefficient of the collapsed rock mass and the residual crushing and swelling coefficient of the collapsed rock mass; Based on the crushing and swelling characteristics of the top-cutting collapsed rock mass, the crushing and swelling amount of collapsed gangue within the top-cutting range on both sides is calculated; When the actual mining volume reaches the amount of collapsed gangue and expansion, the mining height at this time is taken as the optimal top cutting height.

2. The method for designing the top cutting height of coal pillar-free self-forming roadway mining according to claim 1 is characterized in that: The stress-strain relationship of the collapsed rock mass is: Among them, σ1 represents the vertical stress on the collapsed rock mass, E1 represents the initial elastic modulus of the rock mass, ε1 represents the axial strain of the collapsed rock mass when the stress is σ1, and ε m represents the maximum possible axial strain of the collapsed rock mass, σ c Indicates rock mass strength; The calculation method of the initial expansion coefficient of the collapsed rock mass includes: Among them, K1 represents the initial expansion coefficient of the collapsed rock mass, t1 represents the initial expansion height of the collapsed rock mass, and t represents the initial height of the rock mass; The calculation method of the residual expansion coefficient of the collapsed rock mass includes: Among them, K2 represents the residual expansion coefficient of collapsed rock mass, γ represents the average bulk density of overlying rock strata, and h represents the burial depth of coal seam / rock strata.

3. The method for designing the top cutting height of self-forming roadway mining without coal pillars according to claim 1 is characterized in that: The method for calculating the amount of broken and expanded rock in the double-side cutting range includes: Calculate the amount of rock expansion in the i-th layer: in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of the double-sided top cutting; The overburden within the range of the double-sided cutting top is calculated to obtain the final amount of collapse and expansion of the gangue: Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

4. A system for designing the top cutting height of coal pillar-free self-forming lane mining, the system applying the method described in any one of claims 1 to 3, characterized in that: include: Swelling characteristic analysis module, swelling amount calculation module and top cutting height confirmation module; The crushing and swelling characteristics analysis module analyzes the crushing and swelling characteristics of the top-cutting and collapsing rock mass through numerical simulation and similar simulation tests according to the size of the stope, the advancement length of the working face and the thickness of the overburden roof. The crushing and swelling characteristics of the top-cutting and collapsing rock mass include: the stress-strain relationship of the collapsing rock mass, the initial crushing and swelling coefficient of the collapsing rock mass and the residual crushing and swelling coefficient of the collapsing rock mass; The crushing and expansion amount calculation module calculates the crushing and expansion amount of collapsed gangue within the double-side cutting range based on the crushing and expansion characteristics of the cutting top collapsed rock mass; When the actual mining volume reaches the amount of collapsed gangue expansion, the top cutting height confirmation module uses the mining height at this time as the optimal top cutting height.

5. A system for designing the top cutting height of coal pillar-free self-forming roadway mining according to claim 4, characterized in that: The stress-strain relationship of the collapsed rock mass is: Among them, σ1 represents the vertical stress on the collapsed rock mass, E1 represents the initial elastic modulus of the rock mass, ε1 represents the axial strain of the collapsed rock mass when the stress is σ1, and ε m represents the maximum possible axial strain of the collapsed rock mass, σ c Indicates rock mass strength; The calculation method of the initial expansion coefficient of the collapsed rock mass includes: Among them, K1 represents the initial expansion coefficient of the collapsed rock mass, t1 represents the initial expansion height of the collapsed rock mass, and t represents the initial height of the rock mass; The calculation method of the residual expansion coefficient of the collapsed rock mass includes: Among them, K2 represents the residual expansion coefficient of collapsed rock mass, γ represents the average bulk density of overlying rock strata, and h represents the burial depth of coal seam / rock strata.

6. A system for designing the top cutting height of coal pillar-free self-forming roadway mining according to claim 4, characterized in that: The method for calculating the amount of broken and expanded rock in the double-side cutting range includes: Calculate the amount of rock expansion in the i-th layer: in, represents the amount of rock expansion in the i-th layer, h i represents the thickness of the i-th rock layer, h n represents the thickness of the nth rock layer, represents the elastic modulus of the i-th rock layer, represents the initial expansion coefficient of the i-th rock layer, Q represents the load from the top rock layer to the surface, represents the bulk density of the i-th rock layer, represents the bulk density of the nth rock layer, and m represents the number of rock layers within the range of the double-sided top cutting; The overburden within the range of the double-sided cutting top is calculated to obtain the final amount of collapse and expansion of the gangue: Among them, F (y)总 Indicates the final amount of collapsed gangue and rock fragmentation.

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