A numerical model construction and parameter design method based on the sliding filling effect of large-angle gangue

Abstract

The present invention provides a numerical model construction and parameter design method based on the sliding filling effect of high-angle gangue, including: obtaining the geological conditions of high-angle coal seam mining; testing the compaction characteristics of gangue falling from the roof of the goaf, and obtaining the σ-ε curve of gangue stress and strain and the gangue expansion coefficient K p ; via FLAC 3D The double yield model was established by numerical simulation software to simulate the compaction process of roof gangue falling. The σ‑ε curves obtained from the test and simulation were fitted, and the physical and mechanical parameters of the gangue falling were obtained by inversion. The length of the filling area L was preliminarily obtained through the quantitative formula of the length of the gangue sliding filling area in the goaf. 初 , combined with the measured data of the working resistance of the support in the high-angle working face, the length of the filling area L is determined. This method is simple and accurate to operate, and can provide a new idea for the study of the mining pressure law of high-angle coal seam mining.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine steep-angle coal seam working face mining, in particular to a numerical model construction and parameter design method based on steep-angle gangue sliding filling effect. Background Art

[0002] High-angle coal seams (generally referring to coal seams with an inclination of 35° to 55°) are recognized as difficult and complex coal seams at home and abroad. Among them, my country's high-angle coal seams are widely distributed in major mining areas. They account for 10% to 20% and 5% to 8% of my country's coal reserves and production respectively. The complexity of the occurrence conditions of high-angle coal seams leads to the complexity of the overburden migration mechanism during the mining of high-angle working faces. Revealing and exploring the regular characteristics of overburden migration in high-angle working faces is of great significance for the safe and efficient mining of high-angle coal seams.

[0003] In this context, a numerical simulation method is proposed to accurately simulate the mine pressure manifestation law of steep-angle coal seam roof caving and gangue sliding filling, so as to study the overburden movement and mine pressure manifestation law of steep-angle mining areas and tunnels under the conditions of steep-angle gangue sliding filling. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a numerical model construction and parameter design method based on the sliding filling effect of large-angle gangue, which adopts numerical simulation, is simple and easy to implement and has high accuracy.

[0005] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] The first object of the present invention is to provide a numerical model construction and parameter design method based on the large-angle gangue sliding filling effect, comprising the following steps:

[0007] (1) Obtain mining geological condition parameters and physical and mechanical parameters of each rock layer in the study area with high dip angle coal seams;

[0008] (2) The compaction characteristics of the gangue falling from the goaf roof were tested to obtain the σ-ε test curve of gangue stress and strain and the gangue expansion coefficient K. p ;

[0009] (3) A double yield model is established to simulate the compaction process of gangue falling from the roof of the goaf, and a σ-ε simulation curve of gangue stress and strain is obtained. The σ-ε test curve is fitted with the σ-ε simulation curve, and the physical and mechanical parameters of gangue falling from the goaf are obtained by inversion;

[0010] (4) The preliminary filling area length L is obtained by using the quantitative formula of the length of the filling area caused by the falling gangue sliding in the goaf. 初, combined with the measured data of the working resistance of the support at the large-angle working face, determine the length L of the filling area of ​​the falling gangue;

[0011] (5) A numerical model of large-scale mining field with high-angle gangue sliding filling is constructed based on the mining geological condition parameters, the physical and mechanical parameters of the rock strata, the physical and mechanical parameters of the gangue falling in the goaf, and the length L of the gangue filling area.

[0012] Optionally, in one embodiment of the present invention, in step (1), the mining geological condition parameters include: coal seam inclination angle α, coal seam thickness of each rock layer m, burial depth H, working face dip length L1, working face strike length L2, goaf strike length L3.

[0013] Optionally, in one embodiment of the present invention, the coal seam inclination angle α is greater than the natural repose angle of gangue falling from the goaf.

[0014] Optionally, in one embodiment of the present invention, in step (1), the physical and mechanical parameters of each rock formation include: bulk modulus K, shear modulus G, tensile strength R of each rock formation m , internal friction angle φ, cohesion c and density ρ.

[0015] Optionally, in one embodiment of the present invention, in step (3), the double yield model is implemented by FLAC 3D Numerical simulation software was established.

[0016] Optionally, in one embodiment of the present invention, the fitting degree R2>0.8. After the double yield numerical simulation model is established, the compaction process of the roof gangue falling is simulated, and the stress σ and strain ε curves obtained from the test and simulation are fitted. To ensure that the physical and mechanical parameters of the gangue falling obtained by inversion are accurate, the fitting degree R2 should be greater than 0.8.

[0017] Optionally, in one embodiment of the present invention, the FLAC 3D When using numerical simulation software to build a double yield model, the reference factors for the size of the numerical model also include: the actual working surface size and the influence of the model boundary. When using FLAC3D numerical simulation software to build a numerical model size, it is necessary to consider the main factors such as the actual working surface size and the influence of the model boundary.

[0018] Optionally, in one embodiment of the present invention, in step (3), the physical and mechanical parameters of the gangue falling off refer to the physical and mechanical parameters of the compacted gangue sliding filling body, including: bulk modulus K, shear modulus G, tensile strength R m , internal friction angle φ, cohesion c and density ρ.

[0019] Optionally, in one embodiment of the present invention, in step (4), the quantitative formula for the length of the goaf gangue sliding filling area is as follows:

[0020]

[0021] In the formula, K p is the expansion coefficient of falling gangue, L1 is the inclined length of the working face, m1 is the average thickness of the immediate roof, m is the thickness of the coal seam, L3 is the strike length of the goaf, and L 初 is the length of the filling area.

[0022] Optionally, in one embodiment of the present invention, the length L of the falling gangue filling area is the length L of the preliminary filling area. 初 The average value of the length of the filling and top connection area obtained from the measured data of the working resistance of the support on the large-angle working face.

[0023] Optionally, in one embodiment of the present invention, the method further comprises the following steps:

[0024] (6) The accuracy of the numerical model construction is verified by using the measured data of the surrounding rock movement of the two tunnels with large inclination angles and the data of the movement of the two tunnels in numerical simulation.

[0025] Beneficial effects:

[0026] The present invention aims at the practical problem of gangue collapse and sliding filling in the goaf roof of a high-angle coal seam during mining. Through laboratory testing (step 2), finite element numerical simulation inversion (step 3), field data analysis (steps 4 and 6), etc., a three-dimensional high-angle gangue sliding filling numerical model is established, which effectively solves the shortcomings of discrete element numerical simulation software simulating large mining operations for a long time and finite element numerical simulation software being unable to simulate the gangue collapse and compaction process, and provides new ideas and methods for accurately constructing a high-angle gangue sliding filling numerical model and studying the mine pressure law of high-angle coal seam mining. This design method is simple and easy to implement, has strong technical innovation, is highly economical and practical, and has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of gangue sliding filling in the goaf area of ​​a large-angle working face of the present invention;

[0028] Figure 2 The stress σ and strain ε curve of the roof gangue falling test compaction process of the present invention;

[0029] Figure 3 It is a numerical model of compaction characteristics of the falling gangue filling body of the present invention;

[0030] Figure 4 It is the inversion curve of the mechanical property test and simulation results of the falling gangue of the present invention;

[0031] Figure 5 It is a working resistance curve diagram of the working surface support of the present invention;

[0032] Figure 6 It is a schematic diagram of the numerical model of large-angle gangue sliding filling of the present invention;

[0033] Figure 7 The measured and numerically simulated surrounding rock displacement of a square return air lane of the working face of the present invention;

[0034] Figure 8 The measured and numerically simulated surrounding rock displacement of a square transport tunnel of the working face of the present invention;

[0035] In the figure: L1-dipping length of working face, L-length of filling area with fallen gangue, m-coal seam thickness, α-coal seam inclination. DETAILED DESCRIPTION

[0036] The present invention aims to provide a numerical model construction and parameter design method based on the large-angle gangue sliding filling effect, comprising the following steps:

[0037] (1) Obtain the mining geological condition parameters and physical and mechanical parameters of each rock layer in the study area with a high dip angle.

[0038] In some examples, the mining geological condition parameters include coal seam inclination α, coal seam thickness m, burial depth H, working face inclination length L1, working face strike length L2, goaf strike length L3. The thickness of each rock layer includes the average thickness of the immediate roof m1. It should be noted that the coal seam inclination, coal seam thickness, burial depth, working face inclination length, working face strike length, etc. referred to in the mining engineering discipline are all average values ​​without special instructions, which are the correct expressions of mining engineering terms, and there is no need to specify that their values ​​are average values.

[0039] In some examples, the physical and mechanical parameters of each rock layer include: bulk modulus K, shear modulus G, tensile strength R m , internal friction angle φ, cohesion c and density ρ and other parameters required for numerical simulation.

[0040] (2) The compaction characteristics of the gangue falling from the goaf roof were tested to obtain the σ-ε test curve of gangue stress σ and strain ε and the gangue expansion coefficient K p .

[0041] (3) Via FLAC 3DThe double yield model was established with numerical simulation software to simulate the compaction process of gangue falling from the roof of the goaf, and the σ-ε simulation curve of gangue stress and strain was obtained. The σ-ε test curve and the σ-ε simulation curve obtained from the test and simulation were fitted respectively, and the physical and mechanical parameters of gangue falling from the goaf were obtained by inversion.

[0042] (4) The preliminary filling area length L is obtained by using the quantitative formula of the length of the filling area caused by the falling gangue sliding in the goaf. 初 , combined with the measured data of the working resistance of the support at the large-angle working face, the length L of the falling gangue filling area is determined.

[0043] (5) A numerical model of large-scale mining field with high-angle gangue sliding filling is constructed based on the mining geological condition parameters, the physical and mechanical parameters of each rock layer, the physical and mechanical parameters of the gangue falling in the goaf, and the length L of the gangue filling area.

[0044] (6) Finally, the accuracy of the numerical model construction was verified by using the measured data of the surrounding rock movement of the two tunnels with large inclination angles and the data of the movement of the two tunnels in the numerical simulation.

[0045] In some examples of the present invention, the quantitative formula for the length of the sliding filling area of ​​the falling gangue is obtained by the following method:

[0046] According to the expansion coefficient K of the falling gangue p , working face inclination length L1, average thickness of immediate roof m1, coal seam thickness m, goaf strike length L3, then the volume of roof after collapse and expansion is V1 = K p L1L3m1;

[0047] After the falling gangue collapses, it slides to the lower part of the goaf, and the length of the filling area is L 初 , the volume of the falling gangue after sliding to the lower part of the goaf is V2=L(m+m1)L3;

[0048] Since the volumes V1 and V2 are approximately equal, the quantitative formula for the length of the sliding filling area of ​​the falling gangue is as follows:

[0049]

[0050] In some examples of the present invention, the size of a numerical model based on the large-angle gangue sliding filling effect needs to consider major factors such as the actual working surface size and the model boundary influence.

[0051] An embodiment of the present invention is further described below in conjunction with the accompanying drawings. According to the following examples, the present invention can be better understood. However, it is easy for those skilled in the art to understand that the specific parameter design, process conditions and results described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0052] Example 1, taking a certain mine as an example, constructs a numerical model and parameter design based on the sliding filling effect of large-angle gangue.

[0053] The specific implementation steps are as follows:

[0054] The designed production capacity of a mine is 1.2Mt / a. Currently, the main coal seam is the 3rd coal seam, and the research area is the 1305S working face. The roof and floor of the working face are mudstone and sandy mudstone, which are easy to fall off. The rock mass is medium intact to broken, and the quality is poor to medium. The geological conditions are complex. It is an unstable roof and floor soft rock of the steeply inclined coal seam. The law of the mine pressure on the working face is complex and unclear.

[0055] (1) Obtain relevant basic parameters

[0056] In order to ensure safe and efficient production of the working face, the law of mine pressure manifestation of the 1305S high-angle working face was studied, and the mining geological condition parameters of the project were obtained as shown below. The thickness of each rock layer and the physical and mechanical parameters of each rock layer are shown in Table 1.

[0057] The strike length of the working face is 2800m (the mineable strike length L2=2580m), the dip length of the working face is L1=177.1m, the average burial depth is H=700m, the average thickness of the 3 coal seams is m=4.65m, and the average dip angle is α=50°.

[0058] Table 1 Physical and mechanical parameters of each rock layer

[0059]

[0060]

[0061] (2) Laboratory testing

[0062] The compaction characteristics of the gangue falling from the goaf of the 1305S working face were tested in the laboratory, and the stress σ and strain ε curve of the gangue falling were obtained as shown in the figure. Figure 2 As shown, the expansion coefficient K of the falling gangue is also obtained p =1.518.

[0063] (3) Finite element numerical simulation inversion

[0064] After the roof collapses, the goaf area forms gangue that has fallen and accumulated. Its mechanical parameters are different from the original mechanical parameters of each rock layer and cannot be directly replaced by the original parameters. Therefore, the present invention designs the finite element numerical simulation inversion step 3 to obtain the physical and mechanical parameters of the gangue that has fallen in the goaf area, as shown in Table 2. It is intended to use the parameters determined in Tables 1 and 2 to construct a mechanical numerical model.

[0065] Via FLAC 3DThe double yield model is established by numerical simulation software to simulate the compaction process of roof fall and gangue. Figure 3 As shown in the figure, displacement boundary constraints are applied to the bottom and surrounding of the model, and the vertical rate is applied to the top of the model to simulate the loading and compaction process. Similar to the conventional method of building a numerical model, the construction of the numerical model also needs to take into account the influence of factors such as the working surface size and the numerical model boundary. After multiple simulations and inversions, the σ-ε simulation curve of stress σ-strain ε in the numerical simulation process of roof caving and gangue compaction was obtained.

[0066] Then, the σ-ε experimental curve and σ-ε simulation curve of stress σ and strain ε obtained from the test and simulation were fitted. The curve fitting results are shown in Figure 4 As shown in Table 2, the physical and mechanical parameters of the gangue falling in the goaf are obtained by inversion, that is, the physical and mechanical parameters of the compacted gangue sliding filling body required by the numerical model.

[0067] Table 2 Physical and mechanical parameters of compacted gangue sliding filling

[0068]

[0069] (4) On-site data analysis, calculation of filling area length L

[0070] The initial filling area length L is obtained from the quantitative formula of the filling area length of the falling gangue sliding 初 , from (1):

[0071]

[0072] Where: L 初 is the length of the initial filling area;

[0073] K p is the expansion coefficient of falling waste rock, which is taken as 1.518;

[0074] L1 is the inclination length of the working face, which is 177.1m;

[0075] m1 is the average thickness of the immediate roof, which is 1.5 m;

[0076] m is the thickness of the coal seam, which is taken as 4.65m;

[0077] Calculate the initial filling area length L 初 =65.57m.

[0078] Analysis of the working resistance of the hydraulic support on the 1305S working face Figure 5As shown, due to the supporting effect of the falling gangue on the roof in the filling and connecting area, the working resistance of the hydraulic support in this area is relatively small. There are 40 hydraulic supports in this area, the inclination length of the working face L1=177.1m, and there are 105 hydraulic supports in total. Therefore, the length of the filling and connecting area is 67.67m, which is slightly different from the theoretical calculation value. The average length L of the filling area is 66.62m.

[0079] (5) Establishment of a three-dimensional high-angle gangue sliding filling numerical model

[0080] According to the mining geological condition parameters, the physical and mechanical parameters of each rock layer, the physical and mechanical parameters of the gangue falling in the goaf, and the length L of the gangue filling area, a large-scale mining field numerical model of large-angle gangue sliding filling is constructed. Among them, the mining geological condition parameters include the coal seam inclination angle α, the coal seam thickness of each rock layer m, the burial depth H, the working face inclination length L1, the working face strike length L2, and the goaf strike length L3.

[0081] After all parameters are determined, the method for constructing the numerical model is the same as that of the ordinary numerical model, which is a basic model construction method and will not be elaborated in detail in the present invention.

[0082] The numerical model diagram is shown in Figure 6 As shown in the figure, the model size is 178m×800m×281m, the inclination angle of the model rock layer is 50°, fixed constraints are applied on the four sides and bottom of the model, 14.11MPa equivalent ground stress is applied on the top, and the working face has a dip length of 177m. In order to simulate the mine pressure characteristics of the working face and the two lanes under real mining conditions, the model is mined for 20m each time, and 66.62m of fallen gangue is filled in the lower part of the goaf after coal seam mining. The physical and mechanical parameters in Table 2 are given to realize the sliding filling of fallen gangue in the goaf with large dip angle.

[0083] (6) Verify the accuracy of numerical model construction

[0084] When the model working face is mined to the position of one square meter, the surrounding rock movement of the two lanes of the working face is derived. Finally, the surrounding rock movement derived by simulation is compared and verified with the surrounding rock movement of the two lanes measured on site at one square meter. Figure 7 , 8 As shown in the figure, the trend and numerical difference between the two curves are small, and the fitting degree R2>0.8. This verifies that the numerical simulation construction and parameter determination are highly accurate.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A numerical model parameter design method based on the large-angle gangue sliding filling effect, characterized in that: The following steps are involved: (1) Obtain mining geological condition parameters and physical and mechanical parameters of each rock layer in the study area with high dip angle coal seams; (2) The compaction characteristics of the gangue falling from the goaf roof were tested to obtain the σ-ε test curve of gangue stress and strain and the gangue expansion coefficient K. p ; (3) A double yield model is established to simulate the compaction process of gangue falling from the roof of the goaf, and a σ-ε simulation curve of gangue stress and strain is obtained. The σ-ε test curve is fitted with the σ-ε simulation curve, and the physical and mechanical parameters of gangue falling from the goaf are obtained by inversion; (4) The preliminary filling area length L is obtained by using the quantitative formula of the length of the filling area caused by the falling gangue sliding in the goaf. 初 , combined with the measured data of the working resistance of the support at the large-angle working face, determine the final length L of the caving gangue filling area; The quantitative formula for the length of the goaf area's gangue sliding filling area is as follows: In the formula, K p is the expansion coefficient of falling gangue, L1 is the inclined length of the working face, m1 is the average thickness of the immediate roof, m is the thickness of the coal seam, and L 初 is the length of the initial filling area; (5) A numerical model of large-scale mining field with high-angle gangue sliding filling is constructed based on the mining geological condition parameters, the physical and mechanical parameters of the rock strata, the physical and mechanical parameters of the gangue falling from the goaf, and the final length L of the gangue filling area.

2. The method according to claim 1, characterized in that: In step (1), the mining geological condition parameters include: coal seam inclination angle α, coal seam thickness of each rock layer m, burial depth H, working face dip length L1, working face strike length L2, goaf strike length L3.

3. The method according to claim 2, characterized in that The coal seam inclination angle α is greater than the natural repose angle of the gangue falling from the goaf.

4. The method according to claim 1, characterized in that The physical and mechanical parameters of each rock layer include: bulk modulus K, shear modulus G, tensile strength R m , internal friction angle Cohesion c and density ρ.

5. The method according to claim 1, characterized in that In step (3), the double yield model is obtained by FLAC 3D Numerical simulation software was established; The goodness of fit R 2 >0.

8.

6. The method according to claim 5, characterized in that Said via FLAC 3D When the double yield model is established using numerical simulation software, the reference factors for the numerical model size also include: actual working surface size and model boundary influence.

7. The method according to claim 1, characterized in that In step (3), the physical and mechanical parameters of the gangue falling off refer to the physical and mechanical parameters of the compacted gangue sliding filling body, including: bulk modulus K, shear modulus G, tensile strength R m , internal friction angle Cohesion c and density ρ.

8. The method according to claim 1, characterized in that: In step (4), the final length L of the gangue filling area is the length L of the initial filling area. 初 The average value of the length of the filling and top connection area obtained from the measured data of the working resistance of the support on the large-angle working face.

9. The method according to claim 1, characterized in that: The method further comprises the following steps: (6) The accuracy of the numerical model construction is verified by using the measured data of the surrounding rock movement of the two tunnels with large inclination angles and the data of the movement of the two tunnels in numerical simulation.

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