CN109002919A - A kind of method of mine working face Forecast of Gas Emission - Google Patents

Abstract

A method for predicting the amount of gas emission in a mine working face, comprising the following steps: according to the effect of mine pressure on the working face, the coal body in front of the working face is divided into the initial compression and plastic deformation area A, the strong compression and destruction of the coal body Zone B and top plate rotation zone C. As the stress increases, the pressure in the coal body increases, so that part of the free gas in this part of the coal body will become adsorbed gas, which is not conducive to the release of gas. The gas release of the working face can be regarded as the release of these two parts, and the gas content of the working face can be expressed approximately by calculating the gas amount in area A and the release amount of the two sides. The invention divides the coal seam in front of the working face into several different areas, and calculates the gas gushing content in the crushed area, so as to obtain the gas gushing amount of the working face. The calculated data is used to guide the mine to take more economical and appropriate measures to prevent gas, thereby improving the mine safety production level.

Description

A method for predicting gas emission in mine working face

technical field

The invention belongs to the technical field of gas control in coal mines, and in particular relates to a method for predicting gas emission in mine working faces.

Background technique

Working face gas prediction is the basis of mine gas prediction. At present, most of mine gas emission predictions use separate source prediction methods and statistical analysis methods. Among them, the split-source prediction method is mainly aimed at the non-layered mining of thin and medium-thick coal seams. For the gas emission prediction of thick coal seam mining, the gas emission coefficient is used for calculation. Due to the differences in specific mining conditions, the relevant coefficients often need to be measured in practice. , it will cause inaccurate prediction data before the measurement is performed. The statistical prediction method requires that the predicted mining face is the same or similar to the sample face in terms of mining method, coal seam occurrence conditions, and gas geological conditions. In the mining of thick coal seams, especially when mining with top-coal caving, the inhomogeneity of coal release, the difference in the influence of different coal thicknesses and roof mine pressures on coal fracture, and the different recovery rates under different mining conditions are currently the main reasons. The forecast method generally has difficulties in the forecasting of top-coal caving mining.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a method for predicting the amount of gas gushing out of mine working faces that can monitor the force status of bolts in real time, improve safety support monitoring, and timely remind workers to discharge potential safety hazards.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a method for predicting the amount of gas emission in a mine working face, comprising the following steps,

(1) According to the effect of mine pressure on the working face, the coal body in front of the working face is divided into the first initial compression and plastic deformation zone A, the strong compression and destruction zone B of the first coal body and the second zone from the back to the front. 1. Roof turning area C;

(2) The regional transportation lane under the mine is parallel to the regional return airway, the regional transportation lane is located on the left side of the regional return airway, and the right side of the regional transportation lane is divided into the second initial compression and plastic deformation from left to right Area A1, the strong compression and destruction area of the second coal body B1 and the second roof rotation area C1, and the left side of the regional return airway are divided from right to left into the third initial compression and plastic deformation area A2, the third Intense compression and damage zone B2 of coal body and third roof turning action zone C2;

(3) For the absolute gas emission Q _A of the coal body in front of the working face in step (1);

(4) Absolute gas emission Q ₁₊₂ for the right side of the regional transport lane and the left side of the regional air return lane in step (2);

(5) Finally, get the gas emission Q=Q _A + Q ₁₊₂ at the working face of the mine.

The determination process of Q _A in step (3) is:

The first initial compression and plastic deformation zone A is adjacent to the strong compression and failure zone B of the first coal body, and its boundary line is formed by the failure support pressure points of each layer of the coal body, and its intercept and the coal wall to The horizontal distance _x0 of the intersection point between the boundary line and the coal seam floor interface can be expressed by the following formula:

Where x ₀ ——horizontal distance from the coal wall to the intersection point of the interface between the curve and the coal seam floor, m;

M—thickness of coal seam, m;

λ——lateral pressure coefficient, , μ is the Poisson's ratio of the coal body;

Φ——internal friction angle of coal body, °;

K—stress concentration factor of peak bearing pressure;

H—coal seam mining depth, m;

γ—average bulk density of overlying strata, ;

C—cohesion of coal body, MPa;

Px——the support strength formed by the support reaction force of the support on the coal wall on the working face, MPa; ;

F _t ——working resistance of support, MN;

α——Inclination angle of support column, °;

B——Bracket width, m.

The curve equation of the boundary line between the first initial compression and plastic deformation zone A and the strong compression and failure zone B of the first coal body can be expressed as:

x= 0.0784H ² +0.376H + x ₀

Then the crushing zone width Lp can be calculated as:

L _p = 0.0784M ² +0.376M+ x ₀

1) Determination of the volume of coal body A in the first initial compression and plastic deformation zone

Due to the strong compression of the first coal body and the damage zone B is the part enclosed by x0 to Lp below the dividing line; assuming that the length of the working face is D meters, the thickness of the coal seam, that is, the mining height is M meters, then the first initial compression and plasticity The coal body volume V _A in the deformation zone A is:

2) The amount of coal gas emission in the first initial compression and plastic deformation zone A

Assume that the cut-off depth of the working face is E meters, and the coal cutting speed of the shearer is V m/min. According to field statistics, the time L/V for cutting coal at the working face is generally not less than 15 minutes, when 15≤L/V≤30 when 31≤L/V≤60, the gas emission of broken coal is 85% of the total gas content; when 61≤L/V , the gas emission from the broken coal body is 95% of the total gas content;

From this, it can be calculated that when the cut-off depth of the working face is E meters, the coal cutting speed of the shearer is V m/min, and the original relative gas content is q cubic meters/ton, the absolute amount of gas emission in area A after coal cutting can be calculated:

In the formula:

K——gas release uniformity coefficient, which can be 1.0-1.5 according to the uniformity of gas occurrence;

——The gas release degree coefficient, when 15≤L/V≤30, take 0.6; when 31≤L/V≤60, take 0.85; when 61≤L/V, take 0.95.

In step (4), the specific determination process of the absolute gas emission Q of the coal body on the right side of the regional transport roadway and the left side of the regional return airway is as follows:

The boundary between the second initial compression and plastic deformation zone A1 and the strong compression and destruction zone B1 of the second coal body, and the third initial compression and plastic deformation zone A2 and the strong compression and destruction zone B2 of the third coal body The dividing line of the left and right sides is arranged symmetrically,

Its intercept and the horizontal distance x1 from the coal wall to the intersection point of the boundary line and the interface _of the coal seam floor can be expressed by the following formula

Px1——leading pressure in front of the coal wall

According to the curve equation of the dividing line:

x= 0.0784H ² +0.376H+X ₁

From this, the width L _p1 of the crushing zone can be calculated as:

L _p1 = 0.0784M ² +0.376M+ X ₁

The fracture conditions of the second initial compression and plastic deformation zone A1 and the third initial compression and plastic deformation zone A2 under the influence of the advanced pressure are similar to those along the working face, because the influence of the advanced pressure has a certain range, and the broken range is approximated 20m;

Then the volume of the crushing zone of the two gangs under the influence of the leading pressure

When the original relative gas content is qm3/ton, under the influence of the leading pressure, the gas emission of the two coal walls is calculated as 50%, then the gas emission Q1+2 of the two coal walls is: .

Adopting the above-mentioned technical scheme, the present invention divides the front of the working face, the right side of the regional transportation lane and the left side of the regional return airway into the initial compression and plastic deformation zone and the coal body according to the effect of the mine pressure on the working face. Intense compression and destruction zone and roof rotation zone. However, the strong compression and damage zone of the coal body and the roof gyration area are in the stress-increased zone. Due to the increase in stress, the pressure in the coal body increases, so that part of the free gas in this part of the coal body will become adsorbed gas. Conducive to the release of gas. Due to the influence of the advanced pressure, the initial compression and plastic deformation zone and the two coal walls in front of the working face are more broken, thereby releasing a certain amount of gas. Therefore, the gas release of the working face can be regarded as the release of these two parts. Therefore, the calculation of the gas volume in the initial compression and plastic deformation zone and the release volume of the right side of the regional transportation roadway and the left side of the regional return airway can be approximated. Expresses the gas content of the working face.

To sum up, the present invention divides the coal seam in front of the working face into several different areas, and calculates the gas emission content in the crushed area, so as to obtain the gas emission amount of the working face. The calculated data is used to guide the mine to take more economical and appropriate measures to prevent gas, thereby improving the mine safety production level.

Description of drawings

Fig. 1 is a schematic diagram of the vertical section of the coal body in front of the working face along the direction parallel to the length of the roadway;

Figure 2 is a schematic diagram of a vertical section along the width direction of the roadway.

Detailed ways

A method for predicting gas emission in mine face of the present invention comprises the following steps,

(1) As shown in Figure 1, according to the effect of mine pressure on the working face, the coal body in front of the working face is divided into the first initial compression and plastic deformation zone A, the strong compression of the first coal body from back to front And the destruction zone B and the first top plate rotation zone C;

(2) As shown in Figure 2, the regional transport lane 1 under the mine is parallel to the regional return air lane 2, the regional transport lane 1 is located on the left side of the regional return air lane 2, and the right side of the regional transport lane 1 is from the left The right is divided into the second initial compression and plastic deformation zone A1, the second strong compression and destruction zone B1 of the coal body, and the second roof rotation zone C1, and the left side of the regional return airway 2 is divided into The third initial compression and plastic deformation zone A2, the third strong compression and destruction zone B2 of the coal body, and the third roof gyration zone C2;

(3) For the absolute gas emission Q _A of the coal body in front of the working face in step (1);

(4) The absolute gas emission Q ₁₊₂ of the coal body on the right side of the regional transportation lane 1 and the left side of the regional return air lane 2 in step (2);

(5) Finally, get the gas emission Q=Q _A + Q ₁₊₂ at the working face of the mine.

The determination process of Q _A in step (3) is:

As shown in Fig. 1, the first initial compression and plastic deformation zone A is adjacent to the strong compression and destruction zone B of the first coal body, and the boundary line is formed by the damage support pressure points of each layer of the coal body. The horizontal distance _x0 from the coal wall to the intersection point of the boundary line and the interface of the coal seam floor can be expressed by the following formula:

Where x ₀ ——horizontal distance from the coal wall to the intersection point of the interface between the curve and the coal seam floor, m;

M—thickness of coal seam, m;

λ——lateral pressure coefficient, , μ is the Poisson's ratio of the coal body;

Φ——internal friction angle of coal body, °;

K—stress concentration factor of peak bearing pressure;

H—coal seam mining depth, m;

γ—average bulk density of overlying strata, ;

C—cohesion of coal body, MPa;

Px——the support strength formed by the support reaction force of the support on the coal wall on the working face, MPa; ;

F _t ——working resistance of support, MN;

α——Inclination angle of support column, °;

B——Bracket width, m.

The curve equation of the boundary line between the first initial compression and plastic deformation zone A and the strong compression and failure zone B of the first coal body can be expressed as:

x= 0.0784H ² +0.376H + x ₀

Then the crushing zone width Lp can be calculated as:

L _p = 0.0784M ² +0.376M+ x ₀

1) Determination of the volume of coal body A in the first initial compression and plastic deformation zone

Due to the strong compression of the first coal body and the damage zone B is the part enclosed by x0 to Lp below the dividing line; assuming that the length of the working face is D meters, the thickness of the coal seam, that is, the mining height is M meters, then the first initial compression and plasticity The coal body volume V _A in the deformation zone A is:

2) The amount of coal gas emission in the first initial compression and plastic deformation zone A

Assume that the cut-off depth of the working face is E meters, and the coal cutting speed of the shearer is V m/min. According to field statistics, the time L/V for cutting coal at the working face is generally not less than 15 minutes, when 15≤L/V≤30 when 31≤L/V≤60, the gas emission of broken coal is 85% of the total gas content; when 61≤L/V , the gas emission from the broken coal body is 95% of the total gas content;

From this, it can be calculated that when the cut-off depth of the working face is E meters, the coal cutting speed of the shearer is V m/min, and the original relative gas content is q cubic meters/ton, the absolute amount of gas emission in area A after coal cutting can be calculated:

In the formula:

K——gas release uniformity coefficient, which can be 1.0-1.5 according to the uniformity of gas occurrence;

——The gas release degree coefficient, when 15≤L/V≤30, take 0.6; when 31≤L/V≤60, take 0.85; when 61≤L/V, take 0.95.

As shown in Figure 2, the specific determination process of the absolute gas emission Q of the coal body on the right side of the regional transportation lane 1 and the left side of the regional return airway 2 in step (4) is as follows:

The boundary between the second initial compression and plastic deformation zone A1 and the strong compression and destruction zone B1 of the second coal body, and the third initial compression and plastic deformation zone A2 and the strong compression and destruction zone B2 of the third coal body The dividing line of the left and right is arranged symmetrically,

Its intercept and the horizontal distance x1 from the coal wall to the intersection point of the boundary line and the interface _of the coal seam floor can be expressed by the following formula

Px1——leading pressure in front of the coal wall

According to the curve equation of the dividing line:

x= 0.0784H ² +0.376H+X ₁

From this, the width L _p1 of the crushing zone can be calculated as:

L _p1 = 0.0784M ² +0.376M+ X ₁

The fracture conditions of the second initial compression and plastic deformation zone A1 and the third initial compression and plastic deformation zone A2 under the influence of the advanced pressure are similar to those along the working face, because the influence of the advanced pressure has a certain range, and the broken range is approximated 20m;

Then the volume of the crushing zone of the two gangs under the influence of the leading pressure

When the original relative gas content is qm3/ton, under the influence of the leading pressure, the gas emission of the two coal walls is calculated as 50%, then the gas emission Q1+2 of the two coal walls is: .

This embodiment does not impose any formal restrictions on the shape, material, structure, etc. of the present invention. All simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention belong to the protection of the technical solution of the present invention. scope.

Claims (3)

1. a kind of method of mine working face Forecast of Gas Emission, it is characterised in that: include the following steps,

(1), according to mine pressure to the function and effect of working face, coal body in front of working face is in turn divided into first from the front to the back Initial compression and plastically deforming area A, the strong compression of the first coal body and destruction area B and the first top plate gyroscopic action area C；

(2), the region transportation roadway under mine is parallel to region air return lane, and region transportation roadway is located at the left side of region air return lane, area The right side side of domain transportation roadway is in turn divided into the strong pressure of the second initial compression and plastically deforming area A1, the second coal body from left to right Contracting and destruction area B1 and the second top plate gyroscopic action area C1, at the beginning of the left side side of region air return lane is in turn divided into third from right to left Begin compression and plastically deforming area A2, the strong compression of third coal body and destruction area B2 and third top plate gyroscopic action area C2；

(3), to the absolute outburst amount Q of coal gas in front of working face in step (1)_A；

(4), the gas absolute discharge of the left side side coal body of the right side side to region transportation roadway in step (2) and region air return lane Q₁₊₂；

(5), gas emission Q=Q at mine working face is finally obtained_A+ Q₁₊₂。

2. a kind of method of mine working face Forecast of Gas Emission according to claim 1, it is characterised in that: step (3) Q in_ADetermination process are as follows:

First initial compression and plastically deforming area A are adjacent with the strong compression of the first coal body and destruction area B, and line of demarcation is by coal What support pressure point was linked to be destroyed in each layer position of body, intercept and the coal wall to line of demarcation and seat earth interface intersection point it is horizontal away from From x₀It can be indicated with following formula:

Wherein x₀--- the horizontal distance of coal wall to curve and seat earth interface intersection point, m；

M --- coal seam thickness, m；

λ --- coefficient of horizontal pressure,, μ is the Poisson's ratio of coal body；

The internal friction angle of Φ --- coal body, °；

K --- the factor of stress concentration of support pressure peak value；

H --- mining depth of coal seams, m；

γ --- overlying rock volume-weighted average,；

The cohesive force of C --- coal body, MPa；

The supporting intensity that Px --- force piece forms the supporting reaction of coal wall, MPa；；

F_t--- working resistance of support, MN；

α --- bracket upright post inclination angle, °；

B --- support width, m；

The curvilinear equation in the line of demarcation of the strong compression and destruction area B of the first initial compression and plastically deforming area A and the first coal body Formula can indicate are as follows:

x= 0.0784H²+0.376 H + x₀

Then it is possible thereby to calculate broken sector width Lp are as follows:

L_p= 0.0784M²+0.376M+ x₀

1) determination of the first initial compression and plastically deforming area A coal body volume

Since the strong compression and destruction area B of the first coal body are lower part there x0 to Lp portion enclosed；If working face is long Degree is D meters, and coal seam thickness, i.e. mining height are M meters, then the coal body volume V of the first initial compression and plastically deforming area A_AAre as follows:

2) the coal gas outburst amount of the first initial compression and plastically deforming area A

If it is E meters that working face, which cuts depth, coalcutter coal cutting speed is V ms/min, and according to field statistics, working face cuts a knife coal The gas emission that time L/V less than 15 minutes, as 15≤L/V≤30, will not generally be crushed coal body is total gas bearing capacity 60%；As 31≤L/V≤60, the gas emission for being crushed coal body is the 85% of total gas bearing capacity；When 61≤L/V, it is crushed coal body Gas emission be total gas bearing capacity 95%；

It is possible thereby to calculate when working face section depth is E meters, coalcutter coal cutting speed is V ms/min, original opposite gas bearing capacity is Q cubic metres/ton hour, the area A gas absolute discharge after coal cutting:

In formula:

K --- gas discharges coefficient of uniformity, can use 1.0-1.5 according to the uniformity coefficient of gas bearing；

--- gas releasing degree coefficient takes 0.6 as 15≤L/V≤30；As 31≤L/V≤60,0.85 is taken；61≤L/ When V, 0.95 is taken.

3. a kind of method of mine working face Forecast of Gas Emission according to claim 2, it is characterised in that: step (4) the gas absolute discharge Q's of the left side side coal body of the right side side and region air return lane of region transportation roadway specifically determined in Journey are as follows:

Line of demarcation between second initial compression and the strong compression and destruction area B1 of plastically deforming area A1 and the second coal body and the Line of demarcation bilateral symmetry cloth between three initial compressions and the strong compression and destruction area B2 of plastically deforming area A2 and third coal body It sets,

Its intercept and the coal wall to line of demarcation and seat earth interface intersection point horizontal distance x₁It can be indicated with following formula

Px1 --- the advanced pressure in front of coal wall

According to the fitting equation in line of demarcation:

x= 0.0784H²+0.376H+X₁

Then it is possible thereby to calculate broken sector width L_p1Are as follows:

L_p1= 0.0784M²+0.376M+ X₁

The second initial compression and plastically deforming area A1 and third initial compression and plastically deforming area A2 under advanced pressure influence Broken situation be similar along working face direction because advanced pressure influence has certain range, take broken range approximation For 20m；

The then volume of two fracture areas helped under advanced pressure influence

Original opposite gas bearing capacity is q cubic metres/ton hour, under the influence of advanced pressure, two help the gas emission of coal wall by 50% calculates, then coal wall two is helped gas emission Q1+2 are as follows:。