CN103940723A - Method for quickly determining permeability of working surface front coal body of underground coal mine in lab - Google Patents

Abstract

The invention discloses a method for determining permeability of a working surface front coal body of an underground coal mine, and belongs to the field of preventing and controlling disasters of a coal mine excavation working surface. The method comprises the following steps of firstly determining a coal mine mining-induced stress monitoring system on the spot to obtain a mining-induced stress distribution curve of the working surface front coal body, and combining with a working surface advancing speed to draw a changing curve of mining-induced stress of a coal body unit, which is at a certain distance from the front part of the working surface, in a working surface advancing process; encoding an axle stress loading and confining pressure unloading synchronization servo control program by utilizing Visual C++, and introducing in a true three-axis permeability testing system computer controller, so as to simulate a mining-induced stress changing process of the coal body unit having the certain distance with the front part of the working surface along with the advancing of the working surface by utilizing a true three-axis permeability test; finally obtaining a permeability value and the changing rule of the permeability value of the coal body unit along with the advancing of the working surface. According to the method for determining the permeability of the working surface front coal body of the underground coal mine, the permeability of the coal body in front of the tunneling working surface and the stope face can be precisely and quickly determined.

Description

The method of mining face under mine front, Fast Measurement colliery, laboratory coal body permeability

Technical field

The invention belongs to channel of coal mining working surface diaster prevention and control field, be specifically related to the method for mining face under mine front, Fast Measurement colliery, a kind of laboratory coal body permeability.

Background technology

Gas Disaster is the very big factor that restriction China's coal-mine industrial security is produced, and the problem such as blast, fire and coal and Gas Outburst that mine gas causes is present in coal production industry and comparatively serious always.Gas drainage is the effective means of administering mine gas disaster, by arrange extraction boring in coal seam, produce negative pressure by drainage pump in boring inside, detach coal body by composing the gas of depositing in coal seam, thereby reduce the gas bearing capacity in coal seam, reduce coal-bed gas pressure, can eliminate to a certain extent the potential threat of mine gas to Safety of Coal Mine Production.

The arrangement of extraction boring is a ring important in gas suction by drilling technique.The spacing of wells is excessive, can cause gas drainage insufficient, the too small waste that can cause high cost and device resource of spacing, and whether drilling depth in preferably scope of coal body crack, pores'growth, the gas drainage effect that can affect equally.Therefore, the Reasonable Arrangement of the spacing of wells, drilling depth, is the key that high-level efficiency draws out methane; The permeability value of coal body can be used as the reference of above-mentioned extraction technological parameter.The comprehensive permeability feature of analyzing workplace front different depth stage coal body, can be driving face firedamp taking-out discharging drilling depth of placement, coal face firedamp taking-out discharging drilling arrangement pitch provides reliable basis.And on-site measurement coal body permeability under conventional situation, technique is loaded down with trivial details, operating environment is poor, and there is relatively large deviation with actual osmotic value in measurement result.

Therefore, in coal production work, be badly in need of the method for a kind of Fast Measurement workplace front coal body permeability, can conveniently measure coal body permeability, for the setting parameter of gas suction by drilling work provides reliable basis.

Summary of the invention

The invention discloses the method for mining face under mine front, Fast Measurement colliery, a kind of laboratory coal body permeability, the method is by measuring the mining-induced stress distribution of workplace front coal body, be plotted in to adopt and move with coal body unit, lower workplace front with the stress changing curve in advance of the face process, and then the synchronous servo control program of establishment axial compression loading and confined pressure unloading, utilize true three-axis penetration rate test macro, accurately simulation mining-induced stress mechanism, realizes the Fast Measurement to workplace front coal body permeability.

Technical solution of the present invention comprises:

A method of measuring mining face under mine front, colliery coal body permeability, comprises the following steps:

Step 1, mensuration workplace front coal body mining-induced stress, it comprises step by step following:

A utilizes computing machine that mining influence plane domain is divided into grid, and using each grid node as measuring point, move towards to arrange several borings at measuring point place along workplace, each adjacent boring is q along workplace strike separation, drilling depth be followed successively by L, L+1p, L+2p, L+3p ... L+np, wherein, L+np<100m, n is nonnegative number;

B preparing experiment hardware, described Experimental Hardware comprises mine monitoring stress system, described mine monitoring stress system comprises system host, borehole stressmeter, guide pole, regulator and stabilized voltage supply;

C installs Experimental Hardware, meets step a, with guide pole, borehole stressmeter is slowly sent into boring assigned address, then injects oil pressure, makes stress induction probe and initiatively coupling of coal and rock; Down-hole part utilizes mining communication cable to connect stabilized voltage supply, modem, builds pressure monitoring substation; Above ground portion connected system main frame;

D starts stabilized voltage supply, and described borehole stressmeter is converted into stress in coal bed the oil pressure of hydraulic oil, and oil pressure is converted into electric signal again, finally transfers pressure transmission to system host, and described system host is used for collecting Monitoring Data and it is classified, is processed;

Step 2, drafting coal body element stress change curve,

The data that monitor in above-mentioned steps d are added up, make form, describe workplace front coal body mining-induced stress σ ₁, σ ₂, σ ₃distribution on coal body depth direction X, binding isotherm draws mining-induced stress σ in three directions that workplace front coal body internal element carries then ₁, σ ₂, σ ₃stress value in the same time not in advance of the face process, carries out record with form, according to list data, taking time t as transverse axis, taking mining-induced stress value as the longitudinal axis, carry out curve fitting by MATLAB software, the mining-induced stress change curve of t in time in square coal body unit in face of drawing;

Step 3, establishment axial compression loading, confined pressure unloading synchronous servo control program,

Taking the coal body element stress change curve drawn in step 2 as foundation, utilize Visual C++ programming language to write axial compression loading and confined pressure unloading synchronous servo control program, import true three-axis penetration rate test macro Computer Control Unit;

Step 4, true three-axis penetration rate test macro are measured coal body permeability, and it comprises step by step following:

E makes coal body test specimen, samples of coal pulled, and being processed into is highly l, and the rectangular parallelepiped test specimen that cross-sectional area is A, is placed in vacuum drying chamber, and heating, drying obtains coal body test specimen;

F installs, and utilizes boring and coring sampling method to arrange boring at workplace, packs above-mentioned coal body test specimen into true three-axis penetration rate test bed;

G starts, and starts Computer Control Unit, and described coal body test specimen three-dimensional stress initial value is set according to the accurate hydrostatic force state in coal seam, i.e. σ ₁=σ ₂=σ ₃=γ h, applies methane gas pressure, inlet end gas pressure P ₁for coal-bed gas pressure, outlet side gas pressure P ₂for near air pressure workplace;

H operation, operation axial compression loading and confined pressure unloading synchronous servo control program complete the simulation of mining-induced stress mechanism in time t, after gas efflux velocity is stable, measure gas seepage flow Q ₀, binding isotherm calculates coal body test specimen permeability K, and obtaining the workplace front degree of depth is the permeability of coal body unit, L place.

As a preferred version of the present invention, in above-mentioned steps h, calculate permeability according to following formula (1):

$K=\frac{2Q_0{P}_0\mathrm{\&mu;l}}{(P_1^2-P_2^2)A}---\left(1\right)$

In formula: K---permeability, md;

P ₀---atmospheric pressure, MPa;

Q ₀---gas seepage flow, cm ³/ s;

μ---gas viscosity coefficient, gets 0.0158cPa;

L---coal body height of specimen, cm;

P ₁---inlet end gas pressure, MPa;

P ₂---outlet side gas pressure, MPa;

A---test specimen cross-sectional area, cm ².

The useful technique effect that the present invention brings:

The method that the invention discloses mining face under mine front, Fast Measurement colliery, a kind of laboratory coal body permeability, the method can be measured the permeability of driving face and coal face front coal body accurately and rapidly; The comprehensive permeability feature of analyzing workplace front different depth stage coal body, can be driving face firedamp taking-out discharging drilling depth of placement, coal face firedamp taking-out discharging drilling arrangement pitch provides reliable basis, contribute to promote coal bed gas drainage effect, control coal-mine gas disaster, thereby promote the safety of coal production work and stablize; Compare traditional coal body permeability determination technology, this technology has been save loaded down with trivial details site technique, convenient, quick, has reduced the time of mensuration work cost.

In addition, can accurately determine coal body test specimen stress path based on field measurement, and then the true three-axis penetration rate test in chamber by experiment, more system and accurate coal body permeability data can be obtained.

Brief description of the drawings

Below in conjunction with accompanying drawing, the present invention is done to further clear, complete explanation:

Fig. 1 is mine monitoring stress system schematic diagram of the present invention;

Fig. 2 is the true three-axis penetration rate of the present invention test macro schematic diagram;

Fig. 3 is coal body of the present invention unit mining-induced stress curve map over time;

In figure, 1, system host, 2, borehole stressmeter, 3, guide pole, 4, demodulator, 5, stabilized voltage supply, 6, pressure monitoring substation, 7, working face wall, 8, gas storage tank, 9, inlet end tensimeter, 10, axial compression charger, 11, confined pressure charger, 12, outlet side tensimeter, 13, flowmeter, 14, gas piping, 15, coal body test specimen, 16, Computer Control Unit.

Embodiment

The invention provides the method for mining face under mine front, Fast Measurement colliery, a kind of laboratory coal body permeability, for making object of the present invention, technical scheme and advantage clearer, clear and definite, below by the example with certain ore deposit 1314 workplace front coal body permeability determination, the present invention is described in more detail.

First to the selected Experimental Hardware of the present invention: mine monitoring stress system and true three-axis penetration rate test macro, do following explanation:

Shown in Fig. 1, mine monitoring stress system, comprise system host 1, borehole stressmeter 2, guide pole 3, regulator 4 and stabilized voltage supply 5, wherein, system host 1 major function is to collect Monitoring Data, on the other hand data are classified, processed, and show data sheet with man-machine dialog interface; Guide pole 3 is for borehole stressmeter 2 is sent into default bore position, and borehole stressmeter 2 is connected with the input port of regulator 4 by circuit, and the output port of regulator 4 is connected with system host, and stabilized voltage supply 5 is connected to it with regulator 4 electricity is provided;

Shown in Fig. 2, true three-axis penetration rate test macro, comprise gas storage tank 8, inlet end tensimeter 9, axial compression charger 10, confined pressure charger 11, outlet side tensimeter 12, flowmeter 13, gas piping 14, coal body test specimen 15 and Computer Control Unit 16, gas piping 14 connects gas storage tank 8, inlet end tensimeter 9, piercing test platform inside, and at outlet side connection traffic meter 13, outlet side tensimeter 12, realize the control to whole system by Computer Control Unit, comprise and control axial compression charger 10, confined pressure charger 11, and regulate the gas pressure of inlet end and outlet side, force value is shown by inlet end tensimeter 9 and outlet side tensimeter 12.

The present invention, a kind of method of measuring mining face under mine front, colliery coal body permeability, comprises the following steps:

Step 1, measures coal body mining-induced stress

First, utilize computing machine that mining influence plane domain is divided into grid, and using each grid node as point position, according to this scheme, move towards to arrange several borings along workplace, adjacent boring is 10m along workplace strike separation, 20m place, workplace front coal body permeability is measured in plan, learns according to field measurement, and workplace front 50m is subject to mining influence with interior coal body, drilling depth is followed successively by 20m, 22m, 24m, 26m,, 50m;

Secondly, in the boring that placement diameter is 80mm successively of each measuring point place, borehole stressmeter 2 is slowly sent into boring assigned address with guide pole 3, then inject oil pressure, make stress induction probe and initiatively coupling of coal and rock, down-hole part utilizes mining communication cable to connect stabilized voltage supply 5, modem 4, builds pressure monitoring substation 6, above ground portion connected system main frame 1, lightning arrester, complete the building work of colliery mine monitoring stress system;

Finally, start stabilized voltage supply 5 switches, borehole stressmeter 2 is converted into stress in coal bed the oil pressure of hydraulic oil, and oil pressure is converted into electric signal again, is finally scaled pressure transmission to ground system main frame 1; System host 1 is controlled whole colliery mine monitoring stress system, carry out communication with down-hole pressure Monitor Sub-Station of Less 6 on the one hand, collect Monitoring Data, on the other hand data are classified, processed, and show data sheet with man-machine dialog interface, obtain under mining influence the horizontal direction mining-induced stress σ of coal body unit, different depth place, workplace front with this ₁, σ ₂and vertical direction mining-induced stress σ ₃;

Step 2, draws coal body element stress change curve

Statistics colliery mine monitoring stress system is measured the data obtained, describes the distribution of coal body inner three-dimensional stress in workplace front on coal body depth direction X, charges to table 1～table 3.

Table 1 horizontal stress σ ₁at the distribution table of coal body depth direction

X	20m	22m	24m	…	50m
						σ 1	11.3MPa	14.5MPa	18.7MPa	…	30.0MPa

Table 2 horizontal stress σ ₂at the distribution table of coal body depth direction

X	20m	22m	24m	…	50m
						σ 2	13.2MPa	13.0MPa	17.2MPa	…	28.5MPa

Table 3 perpendicular stress σ ₃at the distribution table of coal body depth direction

X	20m	22m	24m	…	50m
						σ 3	44.3MPa	45.0MPa	38.2MPa	…	14.7MPa

Known work face advance distance every day 3m, be that fltting speed is 0.125m/h, the distribution on coal body depth direction X according to the described mining-induced stress of table 1～table 3, in conjunction with face propulsion speed, draw the mining-induced stress change procedure of t in time that workplace front coal body internal element carries in advance of the face process, charge to table 4～table 6:

Table 4 coal body unit horizontal stress σ ₁temporal evolution table

t	0	16h	32h	…	240h
						σ 1	30.0MPa	18.7MPa	14.5MPa	…	11.3MPa

Table 5 coal body unit horizontal stress σ ₂temporal evolution table

t	0	16h	32h	…	240h
						σ 2	28.5MPa	17.2MPa	13.0MPa	…	13.2MPa

Table 6 coal body unit perpendicular stress σ ₃temporal evolution table

t	0	16h	32h	…	240h
						σ 3	14.7MPa	38.2MPa	45.0MPa	…	44.3MPa

According to list data, taking time t as transverse axis, taking mining-induced stress value as the longitudinal axis, carry out curve fitting by MATLAB software, the mining-induced stress change curve of t in time in square coal body unit in face of drawing, as shown in Figure 3;

Step 3, establishment axial compression loading and confined pressure unloading synchronous servo control program

Learn by summing up the workplace front coal body mining-induced stress rule of development under different exploitation condition, under mining influence, workplace front coal body has experienced from accurate hydrostatic force state to axial stress and has loaded and the STRESS VARIATION process of confined pressure unloading, in conjunction with correlation theory, taking painted coal body element stress change curve as foundation, utilize Visual C++ programming language to write axial compression loading and confined pressure unloading synchronous servo control program, import true three-axis penetration rate test macro Computer Control Unit;

Step 4, true three-axis penetration rate test macro is measured coal body permeability

First, utilize boring and coring sampling method, arrange boring at workplace, drilling depth should be greater than Affected areas by mining.Samples of coal pulled, being processed into is highly 8cm, cross-sectional area is 25cm ²rectangular parallelepiped coal body test specimen 15, be placed in vacuum drying chamber, be heated to 50 DEG C and keep constant temperature 24h, after Drying and cooling, take out and to pack true three-axis penetration rate into test bed;

Secondly, start Computer Control Unit 16, coal body test specimen three-dimensional stress initial value is set according to the accurate hydrostatic force state in coal seam, i.e. σ ₁=σ ₂=σ ₃=8.73MPa, then applies methane gas pressure, inlet end gas pressure P ₁for coal-bed gas pressure 7.33MPa, outlet side gas pressure P ₂for near air pressure 0.12MPa workplace;

Finally operation, operation axial compression loading and confined pressure unloading synchronous servo control program, complete within a certain period of time the simulation of mining-induced stress mechanism, after gas efflux velocity is stable, measure gas seepage flow by gas flow meter 13, the following formula of correlation parameter substitution (1), calculates coal body test specimen permeability K value for 2.3md.

$K=\frac{2Q_0{P}_0\mathrm{\&mu;l}}{(P_1^2-P_2^2)A}---\left(1\right)$ 。

Claims (2)

1. a method of measuring mining face under mine front, colliery coal body permeability, is characterized in that, comprises the following steps:

Step 1, mensuration workplace front coal body mining-induced stress, it comprises step by step following:

A utilizes computing machine that mining influence plane domain is divided into grid, and using each grid node as measuring point, move towards to arrange several borings at measuring point place along workplace, each adjacent boring is q along workplace strike separation, drilling depth be followed successively by L, L+1p, L+2p, L+3p ... L+np, wherein, L+np<100m;

B preparing experiment hardware, described Experimental Hardware comprises mine monitoring stress system, described mine monitoring stress system comprises system host, borehole stressmeter, guide pole, regulator and stabilized voltage supply;

C installs Experimental Hardware, meets step a, with guide pole, borehole stressmeter is slowly sent into boring assigned address, then injects oil pressure, makes stress induction probe and initiatively coupling of coal and rock; Down-hole part utilizes mining communication cable to connect stabilized voltage supply, modem, builds pressure monitoring substation; Above ground portion connected system main frame;

D starts stabilized voltage supply, and described borehole stressmeter is converted into stress in coal bed the oil pressure of hydraulic oil, and oil pressure is converted into electric signal again, finally transfers pressure transmission to system host, and described system host is used for collecting Monitoring Data and it is classified, is processed;

Step 2, drafting coal body element stress change curve,

The data that monitor in above-mentioned steps d are added up, make form, describe workplace front coal body mining-induced stress σ ₁, σ ₂, σ ₃distribution on coal body depth direction X, binding isotherm draws mining-induced stress σ in three directions that workplace front coal body internal element carries then ₁, σ ₂, σ ₃stress value in the same time not in advance of the face process, carries out record with form, according to list data, taking time t as transverse axis, taking mining-induced stress value as the longitudinal axis, carry out curve fitting by MATLAB software, the mining-induced stress change curve of t in time in square coal body unit in face of drawing;

Step 3, establishment axial compression loading, confined pressure unloading synchronous servo control program,

Taking the coal body element stress change curve drawn in step 2 as foundation, utilize Visual C++ programming language to write axial compression loading and confined pressure unloading synchronous servo control program, import true three-axis penetration rate test macro Computer Control Unit;

Step 4, true three-axis penetration rate test macro are measured coal body permeability, and it comprises step by step following:

E makes coal body test specimen, samples of coal pulled, and being processed into is highly l, and the rectangular parallelepiped test specimen that cross-sectional area is A, is placed in vacuum drying chamber, and heating, drying obtains coal body test specimen;

F installs, and utilizes boring and coring sampling method to arrange boring at workplace, packs above-mentioned coal body test specimen into true three-axis penetration rate test bed;

G starts, and starts Computer Control Unit, and described coal body test specimen three-dimensional stress initial value is set according to the accurate hydrostatic force state in coal seam, i.e. σ ₁=σ ₂=σ ₃=γ h, applies methane gas pressure, inlet end gas pressure P ₁for coal-bed gas pressure, outlet side gas pressure P ₂for near air pressure workplace;

H operation, operation axial compression loading and confined pressure unloading synchronous servo control program complete the simulation of mining-induced stress mechanism in time t, after gas efflux velocity is stable, measure gas seepage flow Q ₀, binding isotherm calculates coal body test specimen permeability K, and obtaining the workplace front degree of depth is the permeability of coal body unit, L place.

2. the method for mining face under mine front, mensuration according to claim 1 colliery coal body permeability, is characterized in that: in described step h, calculate permeability according to following formula (1):

$K=\frac{2Q_0{P}_0\mathrm{\&mu;l}}{(P_1^2-P_2^2)A}---\left(1\right)$

In formula: K---permeability, md;

P ₀---atmospheric pressure, MPa;

Q ₀---gas seepage flow, cm ³/ s;

μ---gas viscosity coefficient, gets 0.0158cPa;

L---coal body height of specimen, cm;

P ₁---inlet end gas pressure, MPa;

P ₂---outlet side gas pressure, MPa;

A---test specimen cross-sectional area, cm ².