CN102505943B - Water conservation coal cutting method for small and medium-sized coal mines in waterhead area - Google Patents

Abstract

The invention discloses a water conservation coal cutting method for small and medium-sized coal mines in a waterhead area. The method comprises the following steps: 1, defining the position of a coal bed, that is, defining the thickness and the buried depth of the coal bed in an exploited coal mine according to a boring log; 2, defining exploitation parameters, that is, defining a roof rock beam bearing load, the higher limit value Lmax of the width of an exploitation strip, and the lower limit value Dmin of the width of a coal pillar; 3, defining an exploitation scheme, that is, defining the mining and the reservation widths during strip exploitation according to the Lmax and the Dmin, wherein the width L0 of a strip exploited during strip exploitation is smaller than or equal to Lmax, and the width D0 of a reserved coal pillar is larger than or equal to Dmin; and 4, exploiting, that is, exploiting the coal bed according to the conventional strip exploitation method, and reserving a coal pillar of which the width is D0 every time when a strip of which the width is L0 is exploited. The water conservation coal cutting method has the advantages that the design is reasonable; the implementation is convenient; the maneuverability is high; the using effect is good; and the problems of easily caused great loss of the phreatic water resource, and poor water conservation coal cutting effect during the conventional exploitation of the small and medium-sized coal mines in the waterhead area are solved.

Description

A kind of water head site medium and small colliery water-protection coal-mining method

Technical field

The invention belongs to the coal mining technical field, especially relate to a kind of water head site medium and small colliery water-protection coal-mining method.

Background technology

" water protection mining " problem in big coalfield, northern Shensi at the beginning of the exploitation of Shen Fu mining area, has just caused the concern of each side.The North Shaanxi gross area 8.06 * 104km ², account for 39.2% of Shaanxi Province's gross area.Wherein contain water surface area 9.5 * 104hm ², account for 24.5% of the whole province's water surface area.The gross amount of water resources of North Shaanxi only is 10.9% of Shaanxi Province, and water resource is 849m per capita ³/ people is 72% of Shaanxi Province's water resource of per capita, 35% of national per capita share.This shows that the water resources quantity of North Shaanxi is comparatively poor.Thereby the importance of " water protection mining " problem in big coalfield, northern Shensi is subjected to the attention of each side for many years.Bury shallowly at the coal seam, northern Shensi, there are the characteristics of desert type river and drought-enduring vegetation in the face of land, and water conservation mainly is to guarantee valuable and the diving resource favourable to the growth conditions of vegetation, stops further developing of face of land desertification.A large amount of mining Practice mainly concentrated in the exploitation of large-scale, super-huge mine in the past, because work plane overlength, the overlength work plane has surpassed 400m at present, advance distance reaches 3Km～5Km, and adopt whole caving methods to handle top board, the longwell retrusive advances, thereby cause the diving resource to run off in a large number, overlying strata are destroyed and water preventing ability variation situation in conjunction with seam mining in its water-retaining production, work plane stays establishes the certain altitude barrier pillar, and it is unsatisfactory to set up " water protection mining " effect in shallow draining seedbed at coal-smits burnt rock band.

Band exploitation is that the coal seam that will exploit is divided into more regular band and exploits; and adopt one during actual the exploitation; stay one; and utilize the coal column that keeps to support overlying rock; thereby reduce the overlying strata depression; movement and the distortion on the control face of land, and reach the part exploitation method that purpose is protected on ground.Comprise hydraulic filling band, waste filling band, inbreak band, layering inbreak band, close-in seams group band, become to adopt and stay than band under band, irregular band and the old dead zone of ancient little kiln etc. from the arrangement form of band and exploitation method.Although band exploitation recovery ratio is low, resources loss is serious, but because village, China mining area is intensive, removal charge is huge, for the liberation village presses down coal, band exploitation is as a kind of special coal-mining method that reduces ground settlement, and each mining area was all used the band exploitation and carried out the coal mining underbuildings practice in recent years.

Summary of the invention

Technical problem to be solved by this invention is at above-mentioned deficiency of the prior art, a kind of water head site medium and small colliery water-protection coal-mining method is provided, it is reasonable in design, realization is convenient, workable and result of use good, what exist in the time of effectively solving existing water head site medium and small colliery exploitation easily causes multiple practical problems such as the diving resource runs off in a large number, the water protection mining effect is relatively poor.

For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of water head site medium and small colliery water-protection coal-mining method, and the colliery of exploiting is the colliery that is positioned at water head site, its water protection mining exploitation method may further comprise the steps:

Step 1, position, coal seam are determined: according to routine probing geological record method used in the process of coal mining, the exploitation colliery is drilled, and obtain after the bore hole columnar section in the colliery of exploiting, according to described bore hole columnar section, determine thickness and the buried depth in the existing coal seam in the colliery of exploiting, described seam roof is made up of a plurality of rock stratum and successively lay from the bottom to top a plurality of described rock stratum; Simultaneously, determine the thickness of a plurality of rock stratum in the described top board respectively according to described bore hole columnar section;

Wherein, the quantity of a plurality of described rock stratum is n, and n described rock stratum is respectively first rock stratum, second rock stratum from the bottom to top ... n rock stratum, and the thickness of n described rock stratum is respectively h from the bottom to top ₁, h ₂H _n

Step 2, operational parameter determine that its deterministic process is as follows:

201, top board rock beam bearing load is determined, its deterministic process may further comprise the steps:

2011, the mechanical properties of rock of each rock stratum of top board test: according to the mechanical properties of rock method of testing of routine, respectively the mechanical properties of rock parameter of a plurality of described rock stratum in the step 1 is tested, the mechanical properties of rock parameter of each rock stratum that test draws, described mechanical properties of rock parameter comprises unit weight, tensile strength and modulus of elasticity; Wherein, the unit weight of the n that draws described rock stratum of test is respectively γ from the bottom to top ₁, γ ₂γ _n, the modulus of elasticity of n described rock stratum is respectively E ₁, E ₂E _n

2012, top board rock beam institute bearing load calculates:

According to formula ${\left(q_i\right)}_1=\frac{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3({\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+{\mathrm{\&gamma;}}_2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2+...+{\mathrm{\&gamma;}}_i{h}_i)}{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3+E_2{{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2}^3+...+E_i{h_i}^3},$ The formed load of combined influence is carried out to first rock stratum in i the rock stratum that calculating is laid from the bottom to top from first rock stratum, i=1,2 in the formula ... n;

And calculate i rock stratum combined influence carried out when forming load in first rock stratum, to described i+1 rock stratum of laying from the bottom to top from first rock stratum to the formed load (q in first rock stratum _I+1) ₁With i rock stratum to the formed load (q in first rock stratum _i) ₁Carry out difference relatively: when difference relatively draws (q _I+1) ₁＜(q _i) ₁The time, illustrate that absciss layer takes place in i the rock stratum of i+1 rock stratum and its underpart, i=m, and (q at this moment _m) ₁Be described seam roof rock beam institute bearing load, m is positive integer and m＜n;

202, the width higher limit of exploitation band determines that its deterministic process may further comprise the steps:

2021, described top board rock beam is reduced to simply supported beam analysis: and described simply supported beam is the simply supported beam under the evenly distributed load effect; The normal stress at any point A place is on the described simply supported beam

M in the formula _xBe the moment of flexure of A place on cross section on the described simply supported beam, y be the A place to the distance of described simply supported beam neutral axis, t is the thickness of described simply supported beam and the thickness sum of m the rock stratum that t=lays from the bottom to top from first rock stratum;

2022, maximum positive pressure stress and maximum draw normal stress to convert: the maximal bending moment M of described simply supported beam _Max=qL ²/ 8, L is the lateral length of described simply supported beam in the formula; The positive pressure stress that bear in upside outward flange place, described simply supported beam middle part is maximum positive pressure stress, the normal stress that draws that bear in downside outward flange place, described simply supported beam middle part is that maximum is drawn normal stress, the downside outer edge at described simply supported beam middle part and upper edge place are equal to t/2 to the distance y of described simply supported beam neutral axis, and described maximum positive pressure stress draws the numerical value of normal stress to equate with maximum and the two is equal to

2023, the actual normal stress that bears of top board rock beam calculates: the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F},$ F is safety factor and F=2～4 in the formula, R _lBe the tensile strength of described top board rock beam, described top board rock beam is made up of and j 〉=1 j rock stratum: when j=1, illustrate that described top board rock beam is a rock stratum and R _lTensile strength for this rock stratum; When j＞1, R _lTensile strength average for j rock stratum forming described top board rock beam;

2024, the width higher limit converts: with the σ that calculates in the step 2023 _eFormula in the substitution step 2022 ${\mathrm{\&sigma;}}_{\max }=\frac{3q{L}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2},$ Conversion draws the width higher limit of exploitation band $L_{\max }=\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}},$ Q is the (q that calculates in the step 201 in the formula _m) ₁

203, the coal pillar width lower limit is determined, its deterministic process is as follows:

2031, coal column yield region width calculates:

According to formula

Calculate coal column yield region width r _p, M is the average height in coal column height and the described coal seam of M=in the formula, and d is the exploitation disturbance factor and d=1.2～3.0, and β is coefficient of horizontal pressure and β=0.25～0.40 at coal column yield region and the interval interface of elastic kernel place, and C is the cohesion of coal seam and top board contact surface,

Be the angle of friction of coal seam and top board contact surface, σ _ZlBe coal column ultimate strength, P _xThe lateral restriction of the rib wherein unit of M is m, C, σ _ZlAnd P _xUnit be MPa; I is influence coefficient and i=3～1.5; Along with the continuous increase of M, i constantly reduces;

2032, the coal pillar width lower limit is determined: according to the coal column yield region width r that calculates in the step 2031 _p, determine the width lower limit D of coal column _Min=2r _p+ r ₀, r wherein ₀Minimum value and r for coal column elastic kernel sector width ₀=0.1m～1m;

Step 3, recovery scheme are determined: according to the L that calculates in the step 2024 _MaxWith the D that calculates in the step 2032 _Min, determine that adopting in the strip coating method recovery process stay yardstick, wherein the width L of the band of exploiting in the strip coating method recovery process ₀≤ L _MaxAnd the width D of the coal column that stays ₀〉=D _Min

Step 4, exploitation: according to conventional band exploitation method described coal seam is exploited, and in the actual recovery process, width of every exploitation is L ₀Band, staying and establishing a width is D ₀Coal column.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: after described coal seam is exploited according to conventional band exploitation method described in the step 4, forming a plurality of width is L ₀The band goaf, and to be installed with a width between adjacent two described band goafs be D ₀Strip coal pillar; And after according to conventional band exploitation method described coal seam being exploited, also need carry out closely knit filling with inserts respectively to a plurality of described bands goaf from front to back, and a plurality of fill areas of corresponding formation; A plurality of described bands goaf is carried out respectively in the closely knit filling process, from front to back adjacent two described strip coal pillars between the fill area are exploited.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method, it is characterized in that: described coal seam is carried out in the recovery process according to conventional band exploitation method described in the step 4, arrange a plurality of coal mining sections or a plurality of coal-face in described coal seam, between adjacent two coal mining sections or adjacent two coal-faces by being installed with an isolated coal pillar; And after exploitation finished, all forming a plurality of width in each coal mining section or each coal-face was L ₀The district in the band goaf, being installed with a width between the band goaf in adjacent two described districts is D ₀The district in strip coal pillar;

Determine adopting when staying yardstick in the strip coating method recovery process described in the step 3, also need the width minimum value of described isolated coal pillar is determined, in the middle of described isolated coal pillar comprises water proof band and two be laid in respectively described in the middle of water proof band both sides the work plane yield region of exploitation and now exploit the work plane yield region, and the width minimum value deterministic process of described isolated coal pillar is as follows:

Step I, middle water proof bandwidth L ₂₀Calculate: respectively according to side direction hydrostatic pressure coal pillar width design formulas $L_{}$ ${}_{21}=0.5\mathrm{KM}\sqrt{\frac{3P}{K_P}}$ Or empirical formula $L_{}$ ${}_{22}=\frac{P}{T_s}+10,$ Water proof bandwidth L in the middle of calculating ₂₁With middle water proof bandwidth L ₂₂, K is safety factor and K=2～5 in the formula, and M is that average height and its unit in described coal seam is m, and P is that head pressure and its unit that middle water proof band that test draws bears is kgf/cm ², K _PFor tensile strength and its unit of coal body in the described coal seam is kgf/cm ², T _sThe water bursting coefficient that calculates for test;

Afterwards, the middle water proof bandwidth L to calculating ₂₁With middle water proof bandwidth L ₂₂Carry out difference relatively: work as L ₂₁〉=L ₂₂The time, middle water proof bandwidth L ₂₀=L ₂₁Otherwise, middle water proof bandwidth L ₂₀=L ₂₂

Step II, isolated coal pillar width minimum value L _MinCalculate:

According to formula L _Min=L ₁+ L ₂₀+ L ₃, calculate the width minimum value of described isolated coal pillar, L in the formula ₁And L ₃Be respectively and exploit work plane yield region width and now exploit work plane yield region width, and L ₁=L ₃The coal column yield region width r that calculates in=the step 2032 _p

According to conventional band exploitation method described coal seam is carried out in the recovery process width L that establishes isolated coal pillar that stays between adjacent two coal mining sections or adjacent two coal-faces in the step 4 _I0〉=L _Min

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: the m=1 described in the step 2012, and described seam roof rock beam is first rock stratum; T is the thickness of first rock stratum in the step 2021; L is the lateral length of first rock stratum in the step 2022; The rock beam of top board described in the step 2023 is first rock stratum and R _lTensile strength for first rock stratum.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method, it is characterized in that: before described coal seam is exploited according to conventional band exploitation method described in the step 4, also need according to conventional coal column method for analyzing stability, determined recovery scheme in the employing step 3 is carried out the stability of institute's reserved coal pillar in the band recovery process and analyze.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: described conventional coal column method for analyzing stability is the equivalent material simulating experiment.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: M=3m～8m in the step 2031.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: in the step 2032 along with described seam roof stability weakens r gradually ₀Increase gradually.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: before operational parameter is determined in the step 2, also need definite method of the safe back production upper limit in coal seam routinely, to the safe back production upper limit M in described coal seam _xCalculate, and judge whether to adopt the band exploitation method that described coal seam is exploited according to result of calculation: when the average height M in described coal seam greater than the safe back production that calculates in limited time, then enter step 2 and by the band exploitation method described coal seam exploited; Otherwise, by the broadwall method described coal seam is exploited.

Above-mentioned a kind of water head site medium and small colliery water-protection coal-mining method is characterized in that: to the safe back production upper limit M in described coal seam _xWhen calculating, according to formula $\frac{100M_x}{3.3n_x+3.8}+5.1+\frac{M_x}{n_x}\&le;{\mathrm{<figure-callout\; id="0"\; label="H"\; filenames="HDA0000110458070000031.png"\; state="\{\{state\}\}">H</figure-callout>}}_0,$ 5.1 is correction factor in the formula, n _xBe the layering number of plies in described coal seam, H ₀The average height of top, the described coal seam basement rock that draws for test.

The present invention compared with prior art has the following advantages:

1, method step is simple, realization is convenient and be easy to grasp.

2, reasonable in design, the present invention is rich in water layer and is not damaged in principle guaranteeing that the coal seam is covered, according to the theoretical Breadth Maximum that calculates the exploitation band of mechanics of materials simply supported beam; Guaranteeing to calculate the minimum dimension of strip coal pillar according to the limit equilibrium theory in the Elasticity on the bearing block long term stability principle basis; According to the yield region width of isolating coal column between the limit equilibrium theory meter panel in the Elasticity, according to the middle water proof bandwidth of side direction hydrostatic pressure design formulas and the interval isolated coal pillar of experience check formula calculating dial, finally determine to isolate between the panel rational width of coal column; By calculating maximum exploitation strip width and minimum pillar size, " country rock-coal column group " done the as a whole equivalent material simulating analysis of carrying out, determine the proportioning of each rock stratum in the simulated experiment, analyze the stability of " country rock-coal column group " system, the final reasonability of determining the operational parameter of carrying.

3, result of use is good and practical value is high, and the final recovery scheme of determining is reasonable, and " water protection mining " is effective, can not cause the diving resource to run off in a large number in the recovery process, and recovery ratio is higher.

In sum, the inventive method step is simple, reasonable in design, realization is convenient and workable, result of use is good, the water protection mining of definite recovery scheme effective, what exist in the time of effectively solving existing water head site medium and small colliery exploitation easily causes multiple practical problems such as the diving resource runs off in a large number, the water protection mining effect is relatively poor.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Method flow block diagram when Fig. 1 carries out water protection mining for the present invention.

Fig. 2 by in the present invention's first specific embodiment the bore hole columnar section of exploitation middle and small scale coal mine.

Fig. 3 analyzes the seat earth bearing pressure situation of change schematic diagram that draws for adopting the equivalent material simulating experiment in the present invention's first specific embodiment to selected band recovery scheme.

The band exploitation view that Fig. 4 adopts for carrying out water protection mining in the present invention's first specific embodiment.

Fig. 5 by in the present invention's second specific embodiment the bore hole columnar section of exploitation middle and small scale coal mine.

Description of reference numerals:

1-strip coal pillar; Territory, 2-goaf; 3-coal-face;

4-unmind the zone.

The specific embodiment

A kind of water head site medium and small colliery water-protection coal-mining method as shown in Figure 1, the colliery of exploiting is the colliery that is positioned at water head site, and its water protection mining exploitation method may further comprise the steps:

Step 1, position, coal seam are determined: according to routine probing geological record method used in the process of coal mining, the exploitation colliery is drilled, and obtain after the bore hole columnar section in the colliery of exploiting, according to described bore hole columnar section, determine thickness and the buried depth in the existing coal seam in the colliery of exploiting, described seam roof is made up of a plurality of rock stratum and successively lay from the bottom to top a plurality of described rock stratum; Simultaneously, determine the thickness of a plurality of rock stratum in the described top board respectively according to described bore hole columnar section.

Wherein, the quantity of a plurality of described rock stratum is n, and n described rock stratum is respectively first rock stratum, second rock stratum from the bottom to top ... n rock stratum, and the thickness of n described rock stratum is respectively h from the bottom to top ₁, h ₂H _n

During actual the exploitation, the colliery of exploiting is the middle and small scale coal mine of 300,000 tons/year～900,000 tons/year of output.

Step 2, operational parameter determine that its deterministic process is as follows:

201, top board rock beam bearing load is determined, its deterministic process may further comprise the steps:

2011, the mechanical properties of rock of each rock stratum of top board test: according to the mechanical properties of rock method of testing of routine, respectively the mechanical properties of rock parameter of a plurality of described rock stratum in the step 1 is tested, the mechanical properties of rock parameter of each rock stratum that test draws, described mechanical properties of rock parameter comprises unit weight, tensile strength and modulus of elasticity; Wherein, the unit weight of the n that draws described rock stratum of test is respectively γ from the bottom to top ₁, γ ₂γ _n, the modulus of elasticity of n described rock stratum is respectively E ₁, E ₂E _n

2012, top board rock beam institute bearing load calculates:

According to formula ${\left(q_i\right)}_1=\frac{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3({\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+{\mathrm{\&gamma;}}_2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2+...+{\mathrm{\&gamma;}}_i{h}_i)}{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3+E_2{{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2}^3+...+E_i{{\mathrm{<figure-callout\; id="3"\; label="h\; i"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_i}^3},$ The formed load of combined influence is carried out to first rock stratum in i the rock stratum that calculating is laid from the bottom to top from first rock stratum, i=1,2 in the formula ... n;

And calculate i rock stratum combined influence carried out when forming load in first rock stratum, to described i+1 rock stratum of laying from the bottom to top from first rock stratum to the formed load (q in first rock stratum _I+1) ₁With i rock stratum to the formed load (q in first rock stratum _i) ₁Carry out difference relatively: when difference relatively draws (q _I+1) ₁＜(q _i) ₁The time, illustrate that absciss layer takes place in i the rock stratum of i+1 rock stratum and its underpart, i=m, and (q at this moment _m) ₁Be described seam roof rock beam institute bearing load, m is positive integer and m＜n.

202, the width higher limit of exploitation band determines that its deterministic process may further comprise the steps:

2021, described top board rock beam is reduced to simply supported beam analysis: and described simply supported beam is the simply supported beam under the evenly distributed load effect; The normal stress at any point A place is on the described simply supported beam

M in the formula _xBe the moment of flexure of A place on cross section on the described simply supported beam, y be the A place to the distance of described simply supported beam neutral axis, t is the thickness of described simply supported beam and the thickness sum of m the rock stratum that t=lays from the bottom to top from first rock stratum.

2022, maximum positive pressure stress and maximum draw normal stress to convert: the maximal bending moment M of described simply supported beam _Max=qL ²/ 8, L is the lateral length of described simply supported beam in the formula; The positive pressure stress that bear in upside outward flange place, described simply supported beam middle part is maximum positive pressure stress, the normal stress that draws that bear in downside outward flange place, described simply supported beam middle part is that maximum is drawn normal stress, the downside outer edge at described simply supported beam middle part and upper edge place are equal to t/2 to the distance y of described simply supported beam neutral axis, and described maximum positive pressure stress draws the numerical value of normal stress to equate with maximum and the two is equal to

2023, the actual normal stress that bears of top board rock beam calculates: the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F},$ F is safety factor and F=2～4 in the formula, and Rl is the tensile strength of described top board rock beam, and described top board rock beam is made up of and j 〉=1 j rock stratum: when j=1, illustrate that described top board rock beam is a rock stratum and R _lTensile strength for this rock stratum; When j＞1, R _lTensile strength average for j rock stratum forming described top board rock beam.

2024, the width higher limit converts: with the σ that calculates in the step 2023 _eFormula in the substitution step 2022 ${\mathrm{\&sigma;}}_{\max }=\frac{3q{L}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2},$ Conversion draws the width higher limit of exploitation band $L_{\max }=\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}},$ Q is the (q that calculates in the step 201 in the formula _m) ₁

203, the coal pillar width lower limit is determined, its deterministic process is as follows:

2031, coal column yield region width calculates:

According to formula

Calculate coal column yield region width r _p, M is the average height in coal column height and the described coal seam of M=in the formula, and d is the exploitation disturbance factor and d=1.2～3.0, and β is coefficient of horizontal pressure and β=0.25～0.40 at coal column yield region and the interval interface of elastic kernel place, and C is the cohesion of coal seam and top board contact surface,

Be the angle of friction of coal seam and top board contact surface, σ _ZlBe coal column ultimate strength, P _xThe lateral restriction of the rib wherein unit of M is m, C, σ _ZlAnd P _xUnit be MPa; I is influence coefficient and i=3～1.5; Along with the continuous increase of M, i constantly reduces.

2032, the coal pillar width lower limit is determined: according to the coal column yield region width r that calculates in the step 2031 _p, determine the width lower limit D of coal column _Min=2r _p+ r ₀, r wherein ₀Minimum value and r for coal column elastic kernel sector width ₀=0.1m～1m.

Step 3, recovery scheme are determined: according to the L that calculates in the step 2024 _MaxWith the D that calculates in the step 2032 _Min, determine that adopting in the strip coating method recovery process stay yardstick, wherein the width L of the band of exploiting in the strip coating method recovery process ₀≤ L _MaxAnd the width D of the coal column that stays ₀〉=D _Min

Step 4, exploitation: according to conventional band exploitation method described coal seam is exploited, and in the actual recovery process, width of every exploitation is L ₀Band, staying and establishing a width is D ₀Coal column.

In addition, before described coal seam is exploited according to conventional band exploitation method described in the step 4, also need according to conventional coal column method for analyzing stability, determined recovery scheme in the employing step 3 is carried out the stability of institute's reserved coal pillar in the band recovery process and analyze.

Embodiment 1

As shown in Figure 2, in the present embodiment, the colliery of exploiting is for being positioned at the water head site elm Bu Jie colliery of (also claiming water source protection ground).Elm Bu Jie colliery is located in the Yu Bujie village of Yulin City north of the city 11km, be positioned at the southwestern margin area, the refreshing mining area of elm of national planning, administrative division is subordinate to Yuyang District Niu Jialiang town and has jurisdiction over, the English Million ton/annual of designed productive capacity 0.06Mt/a(when building at the beginning of 1993, namely 1,000,000 tons/year), mine capacity promotes and is 0.30Mt/a after the technological transformation in 2008.Elm is foretold boundary's coal field and is located in loess plateau, northern Shensi the northern fringe and borders on the area with a hair Wu Su desert, and major part is typical aeolian dune and dust storm beach looks in the mining area in, and the desert coverage scale is more than 80%, and based on fixedly sand and semifixed sand, the vegetation covering is better.Nos basement rock exposure in the scope of field with "nine squares", stratum, field with "nine squares" from the bottom to top for system straight sieve group, the 3rd in unite in unite on the Trias forever level ground group, the Jurassic system YAN ' AN FORMATION, the Jurassic system fasten system group, Quaternary system mid Pleistocene series from the stone group, Quaternary system upper Pleistocene series Sa Lawu is plain organizes and Holocene series.2 ^-2Coal seam (i.e. the 2nd exploiting field in the 2nd layer of stratum) is main minable coal seam unique in the field with "nine squares".2 ^-2The coal seam thickness in coal seam in 4.35m～5.57m scope, then 2 ^-2The coal seam average thickness in coal seam is 5.23m, and the buried depth in coal seam is 99m～168m.Wherein, 2 ^-2False roof is that thickness is less than mud stone or the carbonaceous mud stone thin layer of 0.5m in the roof; Directly the top is the siltstone of thickness 2.4m～6.67m, and individual lot pushes up direct tax substantially and is stored on the coal seam, and basic top thickness degree is greater than 20m.2 ^-2Seat earth is mud stone, siltstone and the packsand that thickness does not wait, and is more stable.False roof refers to directly overlay on the industrial coal seam, mechanical strength is low and the part roof strata of difficult formation stress arch, very easily collapses after the coal extraction.Directly the top also claims caving zone, and this part rock stratum has collapsed the old man, is temporarily supported by support at stope, can not remain the contact of transmitting horizontal force on direction of propulsion.

Elm Bu Jie colliery belongs to " water protection mining " zone, and extensive distribution Quaternary system unconsolidated sediment wherein is mainly mid Pleistocene series from stone group yellowish-brown loess in the district, is the good space that underground water stores and migrates.Modern moving dunes on the loess formation provide good condition for oozing under the Atmospheric precipitation." the seven-star town sandstone " that underlies (the straight sieve group J2Z sandstone of system in the Jurassic system), very military hole sandstone (2 ^-2Roof) be thick-huge thick-layer in thick-fine sandstone, it is more stable to distribute, continuity is good.Mostly two-layer sandstone is same water content except there is the mud stone water proof part, rock crack is comparatively grown, and composing to deposit for underground water provides certain condition.The southern side, field with "nine squares" is because 2 ^-2Spontaneous combustion of coal seam makes roof caving, causes certain thickness caving zone and fissure zone, and its no water barrier in top exists, and links up with the loose rock class of Quaternary system aquifer, for underground water provides good condition.Field with "nine squares" water-bearing rock group is divided into two classes, and the one, the loose rock class of Quaternary system and bedrock weathering zone hole, crack phreatic aquifer group comprise that alluvium, Holocene series river valley hole diving, upper Pleistocene series are towards lake layer hole diving and mid Pleistocene series loess crack hole diving; The 2nd, packsand hole, crack interlayer pressure-bearing water-bearing rock group in the Jurassic system.

In the present embodiment, when carrying out the water protection mining exploitation, its recovery process is as follows:

Step 1, position, coal seam are determined: according to routine probing geological record method used in the process of coal mining, the exploitation colliery is drilled, and the bore hole columnar section in the acquisition colliery of exploiting, see for details after Fig. 2, according to described bore hole columnar section, determine thickness and the buried depth in the existing coal seam in the colliery of exploiting, described seam roof is made up of a plurality of rock stratum and successively lay from the bottom to top a plurality of described rock stratum; Simultaneously, determine the thickness of a plurality of rock stratum in the described top board respectively according to described bore hole columnar section.Wherein, the quantity of a plurality of described rock stratum is n, and n described rock stratum is respectively first rock stratum, second rock stratum from the bottom to top ... n rock stratum, and the thickness of n described rock stratum is respectively h from the bottom to top ₁, h ₂H _n

In the present embodiment, described coal seam is that 2-2 coal seam and its average height are 5.2m, and the buried depth in described coal seam is 99m～168m.

In addition, be noted that: before operational parameter is determined in the step 2, also need definite method of the safe back production upper limit in coal seam routinely, to the safe back production upper limit M in described coal seam _xCalculate, and judge whether to adopt the band exploitation method that described coal seam is exploited according to result of calculation: when the average height M in described coal seam greater than the safe back production that calculates in limited time, then enter step 2 and by the band exploitation method described coal seam exploited; Otherwise, by the broadwall method described coal seam is exploited.

Safe back production upper limit M to described coal seam _xWhen calculating, according to formula $\frac{100M_x}{3.3n_x+3.8}+5.1+\frac{M_x}{n_x}\&le;{\mathrm{<figure-callout\; id="0"\; label="H"\; filenames="HDA0000110458070000031.png"\; state="\{\{state\}\}">H</figure-callout>}}_0,$ 5.1 is correction factor in the formula, n _xBe the layering number of plies in described coal seam, H ₀The average height of top, the described coal seam basement rock that draws for test.

In the present embodiment, according to the mechanical properties of rock experimental test result of geotechnical boring, 2 ^-2The coal seam overlying rock belongs to middle gravity die, thereby gravity die overlying strata destruction mobile computing formula carries out the height of water flowing fractured zone expectation in selecting for use.Determine the height of water flowing fractured zone design formulas according to " mine hydrogeology rules ": ${H_{\mathrm{li}}}^{\&prime;}=\frac{100M_x}{3.3n_x+3.8}+5.1,$ N in the formula _x=1(namely calculates by the disposable overall height of adopting), calculate

${H_{\mathrm{li}}}^{\&prime;}=\frac{100M_x}{3.3n_x+3.8}+5.1=\frac{100\&times;5.2}{3.3\&times;1+3.8}+5.1=78.3m\&CenterDot;$

In order to guarantee the safe working of work plane, need stay to establish certain safe coal rock layer protective layer thickness.According to choosing 6A(A=∑ M/n in " building, water body, railway and main roadway coal column stay establish and press the coal mining rules " subordinate list 6-4 regulation, ∑ M-accumulative total is adopted thick; N-layering the number of plies) as calculating protective layer thickness be: $H_b=6A=6\&times;\frac{5.2}{1}=31.2m\&CenterDot;$

Because waterproof safety coal petrography post is made of jointly water flowing fractured zone and protective layer thickness, its vertical height is:

H _sh=H _li+H _b=78.3+31.2=109.5m。

According to " building, water body, railway and main roadway coal column and pressure coal mining rules " last three band law of development, if will guarantee that roof water does not penetrate in the work plane, need satisfy following relationship: H _Sh≤ H ₀Then $\frac{100M_x}{1.6M_x+3.6}+5.6+6\&times;\frac{M_x}{n}\&le;{\mathrm{<figure-callout\; id="0"\; label="H"\; filenames="HDA0000110458070000031.png"\; state="\{\{state\}\}">H</figure-callout>}}_0,$ Can draw and be limited to M in the safe working _x≤ 1.8m.

Therefore, when adopting " building, water body, railway and main roadway coal column with press the coal mining rules " to calculate in back production in limited time, elm foretells that the boundary is main adopts 2 ^-2The working thickness in coal seam must just can adopt the broadwall method less than 1.8m, and then realization " water protection mining ".Thereby, need to adopt with the band mining type and realize 2 ^-2The raising purpose of coal seam full-seam extraction and recovery ratio.

To sum up, the elm fore-telling coal master of circle adopts 2 ^-2Seam mining thickness just can adopt the broadwall method during less than 1.8m, splits band and does not develop into water barrier under the loose aquifer to guarantee to emit, thereby realize " water protection mining " purpose, but cause at least 66% Coal Loss simultaneously.And the band exploitation can be used as a kind of raising recovery ratio, protects ecological water level, and leaves over effective mining type of coal column in the displacement of basement rock stable condition filling mining of following later stage.

Step 2, operational parameter determine that its deterministic process is as follows:

201, top board rock beam bearing load is determined, its deterministic process may further comprise the steps:

2011, the mechanical properties of rock of each rock stratum of top board test: according to the mechanical properties of rock method of testing of routine, respectively the mechanical properties of rock parameter of a plurality of described rock stratum in the step 1 is tested, the mechanical properties of rock parameter of each rock stratum that test draws, described mechanical properties of rock parameter comprises unit weight, tensile strength and modulus of elasticity; Wherein, the unit weight of the n that draws described rock stratum of test is respectively γ from the bottom to top ₁, γ ₂γ _n, the modulus of elasticity of n described rock stratum is respectively E ₁, E ₂E _n

In the present embodiment, (mechanical properties of rock that specifically is test 300 working face mining roof part rock stratum) tested with the mechanical properties of rock parameter of next rock stratum in 6 rock stratum and described coal seam more than the described coal seam, and obtain rock stratum physico-mechanical properties parameter list according to test result

See table 1 for details:

Table 1 rock stratum physico-mechanical properties parameter list

2012, top board rock beam institute bearing load calculates:

According to formula ${\left(q_i\right)}_1=\frac{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3({\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+{\mathrm{\&gamma;}}_2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2+...+{\mathrm{\&gamma;}}_i{h}_i)}{E_1{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1}^3+E_2{{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2}^3+...+E_i{{\mathrm{<figure-callout\; id="3"\; label="h\; i"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_i}^3},$ The formed load of combined influence is carried out to first rock stratum in i the rock stratum that calculating is laid from the bottom to top from first rock stratum, i=1,2 in the formula ... n;

And calculate i rock stratum combined influence carried out when forming load in first rock stratum, to described i+1 rock stratum of laying from the bottom to top from first rock stratum to the formed load (q in first rock stratum _I+1) ₁With i rock stratum to the formed load (q in first rock stratum _i) ₁Carry out difference relatively: when difference relatively draws (q _I+1) ₁＜(q _i) ₁The time, illustrate that absciss layer takes place in i the rock stratum of i+1 rock stratum and its underpart, i=m, and (q at this moment _m) ₁Be described seam roof rock beam institute bearing load, m is positive integer and m＜n.

In the present embodiment, the load (q of the 1st rock stratum itself ₁) ₁=γ ₁h ₁=27.2 * 2.4=65.28KPa.

The formed load of combined influence is carried out to the 1st rock stratum in the 2nd rock stratum ${\left(q_2\right)}_1=\frac{E_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1^3({\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+{\mathrm{\&gamma;}}_2{h}_2)}{E_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1^3+E_2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2^3}=\frac{6.5\&times;{2.4}^3\&times;(27.2\&times;2.4+26.38\&times;10.6)}{6.5\&times;{2.4}^3+9.0\&times;{10.6}^3}=\frac{89.856\&times;(65.28+279.628)}{6.5\&times;{2.4}^3+9.0\&times;{10.6}^3}$ $=2.867\mathrm{KPa}\&CenterDot;$

Because (q ₂) ₁＜(q ₁) ₁, then this moment m=1, and this moment described seam roof rock beam be first rock stratum.That is to say that absciss layer takes place in the rock stratum of second rock stratum and its underpart in the described seam roof, then deadweight is only born in first rock stratum, and the load value on this moment top board rock beam is (q ₁) ₁=0.65kg/cm ²

In the actual recovery process, m also can be greater than 1, and then absciss layer takes place for m the rock stratum of laying from the bottom to top this moment and its rock stratum, top, and then described seam roof rock beam is formed in m the rock stratum of laying from the bottom to top.

202, the width higher limit of exploitation band determines that its deterministic process may further comprise the steps:

2021, described top board rock beam is reduced to simply supported beam analysis: and described simply supported beam is the simply supported beam under the evenly distributed load effect; The normal stress at any point A place is on the described simply supported beam

M in the formula _xBe the moment of flexure of A place on cross section on the described simply supported beam, y be the A place to the distance of described simply supported beam neutral axis, t is the thickness of described simply supported beam and the thickness sum of m the rock stratum that t=lays from the bottom to top from first rock stratum.

In the present embodiment, t is the thickness of first rock stratum, and according to table 1, t=2.4m=240cm.

2022, maximum positive pressure stress and maximum draw normal stress to convert: the maximal bending moment M of described simply supported beam _Max=qL ²/ 8, L is the lateral length of described simply supported beam in the formula; The positive pressure stress that bear in upside outward flange place, described simply supported beam middle part is maximum positive pressure stress, the normal stress that draws that bear in downside outward flange place, described simply supported beam middle part is that maximum is drawn normal stress, the downside outer edge at described simply supported beam middle part and upper edge place are equal to t/2 to the distance y of described simply supported beam neutral axis, and described maximum positive pressure stress draws the numerical value of normal stress to equate with maximum and the two is equal to

In the present embodiment, L is the lateral length of first rock stratum.

2023, the actual normal stress that bears of top board rock beam calculates: the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F},$ F is safety factor and F=2～4 in the formula, R _lBe the tensile strength of described top board rock beam, described top board rock beam is made up of and j 〉=1 j rock stratum: when j=1, illustrate that described top board rock beam is a rock stratum and R _lTensile strength for this rock stratum; When j＞1, R _lTensile strength average for j rock stratum forming described top board rock beam.

In the present embodiment, described top board rock beam is first rock stratum and R _lBe the tensile strength of first rock stratum, and according to table 1, R _l=3.4MPa=34.0kg/cm ²

In the present embodiment, F=2.5, the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F}=\frac{34.0}{2.5}=13.6\mathrm{kg}/{\mathrm{<figure-callout\; id="2"\; label="cm"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">cm</figure-callout>}}^2\&CenterDot;$

2024, the width higher limit converts: with the σ that calculates in the step 2023 _eFormula in the substitution step 2022 ${\mathrm{\&sigma;}}_{\max }=\frac{3q{L}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2},$ Conversion draws the width higher limit of exploitation band $L_{\max }=\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}},$ Q is the (q that calculates in the step 201 in the formula _m) ₁=(q ₁) ₁=0.65kg/cm ²

During Practical Calculation, with the σ that calculates in the step 2023 _eσ in the replacement formula _Max, get the width higher limit that limit span is namely exploited band $L_{\max }=\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}}=\sqrt{\frac{4\&times;{240}^2\&times;13.6}{3\&times;0.65}}=1270\mathrm{cm}=12.7m\&CenterDot;$

203, the coal pillar width lower limit is determined, its deterministic process is as follows:

2031, coal column yield region width calculates:

According to formula

Calculate coal column yield region width r _p, M is the average height in coal column height and the described coal seam of M=in the formula, and d is the exploitation disturbance factor and d=1.2～3.0, and β is coefficient of horizontal pressure and β=0.25～0.40 at coal column yield region and the interval interface of elastic kernel place, and C is the cohesion of coal seam and top board contact surface, Be the angle of friction of coal seam and top board contact surface, σ _ZlBe coal column ultimate strength, P _xThe lateral restriction of the rib wherein unit of M is m, C, σ _ZlAnd P _xUnit be MPa; I is influence coefficient and i=3～1.5; Along with the continuous increase of M, i constantly reduces.

During actual the exploitation, M=3m～8m in the step 2031; And along with the continuous increase of M, i constantly reduces.Formula

Analysis draws according to limit equilibrium theory, coal column ultimate strength σ in the formula _ZlAccording to formula σ _Zl=δ η σ _cCalculate, wherein η is the coal rheology coefficient, σ _cUniaxial compressive strength and its unit of the coal petrography test block that draws for test are MPa.

In the present embodiment, η=0.4 and σ _c=38.2MPa, coal column ultimate strength σ _Zl=δ η σ _c=2.729 (η σ _c) ^0.729=19.9MPa.Simultaneously, M=5.2m, d=1.8, β=0.252, C=3.0MPa,

Thereby,

2032, the coal pillar width lower limit is determined: according to the coal column yield region width r that calculates in the step 2031 _p, determine the width lower limit D of coal column _Min=2r _p+ r ₀, r wherein ₀Minimum value and r for coal column elastic kernel sector width ₀=0.1m～1m.

Actual when the coal pillar width lower limit is determined, in the step 2032 along with described seam roof stability weakens r gradually ₀Increase gradually.

In the present embodiment, according to the width result of calculation of coal column yield region in the step 2031, the nuclear zone coal pillar width is greater than 2r _p=5.8m advises that on-the-spot coal column stays to establish width and be not less than 6.0m, this moment coal column elastic kernel sector width r ₀=0.2m.If the top board condition is relatively poor, advise effective coal column elastic kernel sector width r ₀=1.0m, i.e. coal column elastic kernel sector width r ₀Minimum value be 1.0m, this moment, institute reserved coal pillar width was not less than 6.8m.

That is to say, when the top board condition is better, D _Min=6.0m; And when the top board condition is relatively poor, D _Min=6.8m.

Step 3, recovery scheme are determined: according to the L that calculates in the step 2024 _MaxWith the D that calculates in the step 2032 _Min, determine that adopting in the strip coating method recovery process stay yardstick, wherein the width L of the band of exploiting in the strip coating method recovery process ₀≤ L _MaxAnd the width D of the coal column that stays ₀〉=D _Min

Step 4, exploitation: according to conventional band exploitation method described coal seam is exploited, and in the actual recovery process, width of every exploitation is L ₀Band, staying and establishing a width is D ₀Coal column.

In the actual recovery process, after described coal seam is exploited according to conventional band exploitation method described in the step 4, forming a plurality of width is L ₀The band goaf, and to be installed with a width between adjacent two described band goafs be D ₀Strip coal pillar; And after according to conventional band exploitation method described coal seam being exploited, also need carry out closely knit filling with inserts respectively to a plurality of described bands goaf from front to back, and a plurality of fill areas of corresponding formation; A plurality of described bands goaf is carried out respectively in the closely knit filling process, from front to back adjacent two described strip coal pillars between the fill area are exploited.

In addition, described coal seam is carried out in the recovery process according to conventional band exploitation method described in the step 4, arrange a plurality of coal mining sections or a plurality of coal-face 3 in described coal seam, between adjacent two coal mining sections or adjacent two coal-faces 3 by being installed with an isolated coal pillar; And after exploitation finished, all forming a plurality of width in each coal mining section or each coal-face 3 was L ₀The district in the band goaf, being installed with a width between the band goaf in adjacent two described districts is D ₀The district in strip coal pillar.

Correspondingly, determine adopting when staying yardstick in the strip coating method recovery process described in the step 3, also need the width minimum value of described isolated coal pillar is determined, in the middle of described isolated coal pillar comprises water proof band and two be laid in respectively described in the middle of water proof band both sides the work plane yield region of exploitation and now exploit the work plane yield region, and the width minimum value deterministic process of described isolated coal pillar is as follows:

Step I, middle water proof bandwidth L20 calculate: respectively according to side direction hydrostatic pressure coal pillar width design formulas $L_{}$ ${}_{21}=0.5\mathrm{KM}\sqrt{\frac{3P}{K_P}}$ Or empirical formula $L_{}$ ${}_{22}=\frac{P}{T_s}+10,$ Water proof bandwidth L in the middle of calculating ₂₁With middle water proof bandwidth L ₂₂, K is safety factor and K=2～5 in the formula, and M is that average height and its unit in described coal seam is m, and P is that head pressure and its unit that middle water proof band that test draws bears is kgf/cm ², K _PFor tensile strength and its unit of coal body in the described coal seam is kgf/cm ², T _sThe water bursting coefficient that calculates for test.

Afterwards, the middle water proof bandwidth L to calculating ₂₁With middle water proof bandwidth L ₂₂Carry out difference relatively: work as L ₂₁〉=L ₂₂The time, middle water proof bandwidth L ₂₀=L ₂₁Otherwise, middle water proof bandwidth L ₂₀=L ₂₂

Step II, isolated coal pillar width minimum value L _MinCalculate:

According to formula L _Min=L ₁+ L ₂₀+ L ₃, calculate the width minimum value of described isolated coal pillar, L in the formula ₁And L ₃Be respectively and exploit work plane yield region width and now exploit work plane yield region width, and L ₁=L ₃The coal column yield region width r that calculates in=the step 2032 _p

According to conventional band exploitation method described coal seam is carried out in the recovery process width L that establishes isolated coal pillar that stays between adjacent two coal mining sections or adjacent two coal-faces 3 in the step 4 _I0〉=L _Min

When actual width to isolated coal pillar calculates, should consider to adopt coal column is destroyed and influence, coal column is near stope one side, because the bearing pressure effect, sheet underworld gang in coal seam produces the crack, forms yield band, become strong infiltration area, this part coal body has been lost the water proof ability basically, becomes the remaining deposit band of the coal column with extremely low water-resisting ability, and what really play impermeable role is that the mid portion of coal column is coal column elastic kernel district.Therefore, coal column is that isolated coal pillar is made up of three parts between work plane, has exploited work plane yield region width L ₁, now exploit work plane yield region width L ₃With middle water proof bandwidth L ₂₀, namely isolated coal pillar is made up of yield region and middle elastic kernel district by the coal column two ends.

In the present embodiment, according to the side direction hydrostatic pressure coal pillar width is calculated earlier, and adopt the formula of being derived by mechanics of materials simply supported beam principle $L_{}$ ${}_{21}=0.5\mathrm{KM}\sqrt{\frac{3P}{K_P}}$ Calculate, consider that this mining area hydrogeological conditions is more clearly, and do not have what structure, safety coefficient K=2.5; Coal seam tensile strength K _p=13.2kg/cm ²Ponding absolute altitude in the goaf calculates according to 3 times of mining heights, the head pressure p=1.6kg/cm that the water proof band bears in the middle of drawing thus ², M=5.2m; The middle water proof bandwidth that calculates according to the side direction hydrostatic pressure then ${\mathrm{<figure-callout\; id="21"\; label="L"\; filenames="HDA0000110458070000031.png"\; state="\{\{state\}\}">L</figure-callout>}}_{21}=0.5\mathrm{KM}\sqrt{\frac{3P}{K_P}}=0.5\&times;2.5\&times;5.2\&times;\sqrt{\frac{3\&times;1.6}{13.2}}=3.9m\&CenterDot;$

And formula rule of thumb $L_{}$ ${}_{22}=\frac{P}{T_s}+10$ When calculating, head pressure p=1.6kg/cm ², water bursting coefficient be described in the middle of in the ratio and present embodiment of the maximum hydrostatic pressure (or pressure) that bears of water proof band and its thickness, water bursting coefficient T _s=0.7, the middle water proof bandwidth that calculates of formula rule of thumb then ${\mathrm{<figure-callout\; id="22"\; label="L"\; filenames="HDA0000110458070000031.png"\; state="\{\{state\}\}">L</figure-callout>}}_{22}=\frac{P}{T_s}+10=\frac{1.6}{0.7}+10=12.3m\&CenterDot;$

To L ₂₁And L ₂₂Carry out difference relatively, and get maximum value, be i.e. L ₂₀=L ₂₂=12.3m.

Thereby, isolated coal pillar width minimum value L _Min=L ₁+ L ₂₀+ L ₃=2.9+12.3+2.9=18.1m, thereby in the actual recovery process, as long as exploited work plane and now exploit to stay between the work plane and establish the isolated coal pillar that width is not less than 18.1m, just can satisfy and isolate the anti-requirement of harnessing the river in goaf, the scene of suggestion stays the width of establishing isolated coal pillar to be not less than 20m.

To sum up, the Breadth Maximum of exploitation band is 12.7m; Calculate according to coal column load and stability, particularly consider " continuous beam " feature of band exploitation, the width of strip coal pillar must not be less than 6.0m, if the top board condition is relatively poor, the strip coal pillar width is not less than 6.8m, to guarantee that coal column has the elastic kernel district of certain width, realize the long-time stability of coal column; The width of isolating coal column between the panel should be less than 20.0m.

Determine that thus the method that adopt in present stage elm Bu Jie colliery " water protection mining " is longwell system band coal-mining method: namely mining system adopts longwell to arrange; adopt the band exploitation in the work plane system; stay and establish strip coal pillar roof supporting and upper caldding layer, the protection aquifer.In conjunction with Fig. 4, adopt " adopt 12 and stay 8 " scheme during the band exploitation, it is the band goaf (territory, goaf 2 that corresponding formation 12m is wide) of every exploitation 12m width, (this coal column is strip coal pillar 1 to stay the isolated coal pillar of establishing 8m, namely be in the coal column in a coal mining section or the coal-face 3), Reference numeral 4 indications zone is for unminding regional 4.

In addition, before described coal seam is exploited according to conventional band exploitation method described in the step 4, also need according to conventional coal column method for analyzing stability, determined recovery scheme in the employing step 3 is carried out the stability of institute's reserved coal pillar in the band recovery process and analyze.

In the present embodiment, described conventional coal column method for analyzing stability is the equivalent material simulating experiment.In the actual recovery process, also can adopt the RFPA2D program of the rock failure process numerical experimentation of Northeastern University that above-mentioned recovery scheme is carried out analytical calculation.

In the present embodiment, adopt the equivalent material simulating experimental technique, when the stability of coal column in the band exploitation is carried out sunykatuib analysis, make a similar material model earlier, it specifically is the plane stress shut die type of a length 3m, high 2m and wide 20cm, the model geometric similar proportion is got 1 ︰ 100, and this model can be simulated the limit of mining of buried depth 200m and length 300m.The geometric similarity constant alpha of the model that adopts _L=100, density affinity constant α _Y=1.57, stress similitude constant alpha=α _Lα _Y=100 * 1.57=157.When reality is made plane stress shut die type, used cast material with quartz sand as aggregate, gypsum, calcium carbonate are as cementitious materials and formulated by a certain percentage with water, and place Min layers is located in the model support, are sprinkled into mica powder simulation aspect between layer and the layer.It is as shown in table 2 that model is loaded size, order and material mixture ratio.Mud stone gets 828 in the proportioning, represents that namely quartz sand accounts for 8/9; Gypsum, calcium carbonate account for 1/9 altogether, and wherein gypsum accounts for 2/10, and calcium carbonate accounts for 8/10.

Table 2 elm Bu Jie colliery plane stress shut die section bar material filling proportioning and lift height

In conjunction with Fig. 3, by described plane stress shut die type " adopt 12 and stay 8 " band recovery process being carried out simulated test draws, the bullet nuclear district rate of institute's reserved coal pillar (specifically referring to coal column in the district) remains on more than 60%, it is stable that overlying strata keep, and coal column middle part maximal support pressure 6.38MPa, far below strength limit, thereby the recovery scheme that adopts in the present embodiment can realize the purpose of " water-retaining production ".

Embodiment 2

As shown in Figure 5, in the present embodiment, the colliery of exploiting is two pier collieries, and it is positioned at 21km place, northeast, Yulin City city, Shaanxi Province, is under the jurisdiction of Yuyang District Chinese ephedra Liang Zhen administration, belongs to the place's local mine in the local mine mining area of planning.Two pier collieries are located in loess plateau, northern Shensi the northern fringe and border on the area with hair Wu Su desert.All covered by the Quaternary system unconsolidated formation in the scope of field with "nine squares", the south is loess distribution in blocks, be distributed with along both sides, Liu Xiang river dash, lake accumulated powder sand and inferior sandy soil.Landform loess exposed section is comparatively smooth in the district, and the south is high, and north, middle part are low, and height above sea level is between+1200～+ 1305.Covered no basement rock exposure by Quaternary system drift-sand and loess entirely in the scope of field with "nine squares".The stratum, field with "nine squares" is organized and Holocene series from stone group, Quaternary system upper Pleistocene series Sa Lawu element for the straight sieve group of system, Quaternary system mid Pleistocene series in unite in the Jurassic system YAN ' AN FORMATION, the Jurassic system from the bottom to top.Main coal-bearing strata is the YAN ' AN FORMATION of uniting in the Jurassic system, and wherein minable coal seam is 2 layers, and No. 3 coal seams are last layer minable coal seams in the district, and thickness is big and stable, and the whole district can adopt, and thickness is stabilized in 7.50m～8.73m, average 8.43m.To the east northeast progressive additive, Changing Pattern is obvious by Nan Xi in the coal seam, belongs to the thick-super high seam of stability.The coal seam is buried stable, buried depth 136.81m～196.58m.The bore hole columnar section in No. 3 coal seams, two pier collieries is seen Fig. 5.Have the canescence thick-layer shape of a layer thickness 30.00～38.68m thin in No. 3 roofs-middle grain length stone sand rock, namely reference lamina " very military hole sandstone " is gone up in the zone; No. 3 seat earth is mud stone and powder packsand alternating layers, and coal seam and top, base plate present tangible contact relation.

Two pier collieries belong to " water protection mining " zone, and residing mining area is positioned at mao Wu Su desert and loess plateau, northern Shensi the northern fringe is bordered on the area, and landform is comparatively smooth in the scope of field with "nine squares", relative relief 105m.Belong to continental climate, average rainfall over the years is 410.01mm, and concentrates on for 7～September.The annual mean evaporation capacity is that 1907.2mm is 4.65 times of amount of precipitation.Thereby, belong to the very fragile zone of ecological environment, therefore, water table aquifer and underground reservoir under the protection desert, ecology and sustainable development for this zone are extremely important.

In the present embodiment, carry out water protection mining when exploitation, its recovery process as different from Example 1:

Step 1 is carried out the position, coal seam when determining, in conjunction with Fig. 5, the coal seam of exploiting is that No. 3 coal seams and its average height are 8.43m, and the buried depth in described coal seam is 136.81m～196.58m;

Carry out (the rock stratum that physical property is close, each rock stratum of top board in the step 2011, be reduced to single rock stratum) mechanical properties of rock when test, No. 36 rock stratum more than the coal seam and No. 3 coal seams are tested with the mechanical properties of rock parameter of next rock stratum, and obtain rock stratum physico-mechanical properties parameter list according to test result, see table 3 for details:

Table 1 rock stratum physico-mechanical properties parameter list

When carrying out the bearing load calculating of top board rock beam institute in the step 2012, the load (q of the 1st rock stratum itself ₁) ₁=γ ₁h ₁=27.2 * 7.6=206.72KPa; The formed load of combined influence is carried out to the 1st rock stratum in the 2nd rock stratum:

${\left(q_2\right)}_1=\frac{E_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1^3({\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+{\mathrm{\&gamma;}}_2{h}_2)}{E_1{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_1^3+E_2{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">h</figure-callout>}}_2^3}=\frac{6.5\&times;{7.6}^3\&times;(27.2\&times;7.6+26.38\&times;6.5)}{6.5\&times;{7.6}^3+9.0\&times;{6.5}^3}=202.65\mathrm{kPa}<{\left(q_1\right)}_1;$

Because (q ₂) ₁＜(q ₁) ₁, then this moment m=1, and this moment No. 3 seam roof rock beams be first rock stratum.That is to say that absciss layer takes place in the rock stratum of second rock stratum and its underpart in No. 3 seam roofs, then deadweight is only born in first rock stratum, and the load value on this moment top board rock beam is got (q ₁) ₁=2.07kg/cm ²

In the step 2021 described top board rock beam is reduced to simply supported beam when analyzing, according to table 3, the thickness t of simply supported beam is the thickness of first rock stratum, and t=7.6m=760cm;

Carry out maximum positive pressure stress and maximum in the step 2022 when drawing normal stress to convert, the positive pressure stress that bear in upside outward flange place, described simply supported beam middle part is maximum positive pressure stress, the normal stress that draws that bear in downside outward flange place, described simply supported beam middle part is that maximum is drawn normal stress, the downside outer edge at described simply supported beam middle part and upper edge place are equal to t/2=380cm to the distance y of described simply supported beam neutral axis, and described maximum positive pressure stress and maximum draw the numerical value of normal stress to equate and the two is equal to

L is the lateral length of first rock stratum;

When carrying out in the step 2023 that the top board rock beam is actual to be born normal stress and calculate, described top board rock beam is first rock stratum and R _lBe the tensile strength of first rock stratum, and according to table 3, R _l=2.4MPa=24.0kg/cm ², F=3, the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F}=\frac{24.0}{3.5}=6.9\mathrm{kg}/{\mathrm{<figure-callout\; id="2"\; label="cm"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">cm</figure-callout>}}^2\&CenterDot;$

When carrying out the conversion of width higher limit in the step 2024, with the σ that calculates in the step 2023 _eFormula in the substitution step 2022 ${\mathrm{\&sigma;}}_{\max }=\frac{3q{L}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2},$ Conversion draws the width higher limit of exploitation band $L_{\max }=\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}},$ Q=(q in the formula ₁) ₁=2.07kg/cm ²During Practical Calculation, with the σ that calculates in the step 2023 _eσ in the replacement formula _Max, get the width higher limit that limit span is namely exploited band $L_{\max }=$ $\sqrt{\frac{4{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000110458070000031.png,HDA0000110458070000032.png"\; state="\{\{state\}\}">t</figure-callout>}}^2{\mathrm{\&sigma;}}_e}{3q}}=\sqrt{\frac{4\&times;{760}^2\&times;6.9}{3\&times;2.07}}=1600\mathrm{cm}=16.0m;$ Then exploit the limit span L of band top board _MaxBe 16.0m, consider geology, mining influence factor, advise that on-the-spot band adopts the wide 12.0m of being no more than,

When carrying out the width calculating of coal column yield region in the step 2031, η=0.4 and σ _c=38.2MPa, coal column ultimate strength σ _Zl=δ η σ _c=2.729 (η σ _c) ^0.729=19.9MPa.Simultaneously, M=8.4m, d=2, β=0.252, C=3.0MPa,

Calculate coal column yield region width

Carry out the coal pillar width lower limit in the step 2032 when determining, according to the coal column yield region width r that calculates in the step 2031 _p, determine the width lower limit D of coal column _Min=2r _p+ r ₀, r wherein ₀Minimum value and r for coal column elastic kernel sector width ₀=0.1m～1m, then coal pillar width is greater than 8.6m, advises that on-the-spot coal column stays to establish width and be not less than 9.0m; If the top board condition is relatively poor, coal column effective elasticity nuclear sector width is not less than 1.0m, advises that on-the-spot coal column stays to establish to be not less than 9.6m.

When recovery scheme is determined in the step 3, according to the L that calculates in the step 2024 _MaxWith the D that calculates in the step 2032 _Min, determine that adopting in the strip coating method recovery process stay yardstick, calculate and finally determine that two pier colliery band operational parameters be " adopt 12 and stay 10 ", namely every band of exploiting the 12m width stays coal column in the 10m width district.

When exploiting in the step 4, according to conventional band exploitation method described coal seam is exploited, and in the actual recovery process, the band that width of every exploitation is 12m stays and establishes a width coal column that is 10m.

The above; it only is preferred embodiment of the present invention; be not that the present invention is imposed any restrictions, every any simple modification, change and equivalent structure of above embodiment being done according to the technology of the present invention essence changes, and all still belongs in the protection domain of technical solution of the present invention.

Claims (10)

1. water head site medium and small colliery water-protection coal-mining method, the colliery of exploiting is the colliery that is positioned at water head site, its water protection mining exploitation method may further comprise the steps:

Step 1, position, coal seam are determined: according to routine probing geological record method used in the process of coal mining, the exploitation colliery is drilled, and obtain after the bore hole columnar section in the colliery of exploiting, according to described bore hole columnar section, determine thickness and the buried depth in the existing coal seam in the colliery of exploiting, described seam roof is made up of a plurality of rock stratum and successively lay from the bottom to top a plurality of described rock stratum; Simultaneously, determine the thickness of a plurality of rock stratum in the described top board respectively according to described bore hole columnar section;

Wherein, the quantity of a plurality of described rock stratum is n, and n described rock stratum is respectively first rock stratum, second rock stratum from the bottom to top ... n rock stratum, and the thickness of n described rock stratum is respectively h from the bottom to top ₁, h ₂H _n

Step 2, operational parameter determine that its deterministic process is as follows:

201, top board rock beam bearing load is determined, its deterministic process may further comprise the steps:

2011, the mechanical properties of rock of each rock stratum of top board test: according to the mechanical properties of rock method of testing of routine, respectively the mechanical properties of rock parameter of a plurality of described rock stratum in the step 1 is tested, the mechanical properties of rock parameter of each rock stratum that test draws, described mechanical properties of rock parameter comprises unit weight, tensile strength and modulus of elasticity; Wherein, the unit weight of the n that draws described rock stratum of test is respectively γ from the bottom to top ₁, γ ₂γ _n, the modulus of elasticity of n described rock stratum is respectively E ₁, E ₂E _n

2012, top board rock beam institute bearing load calculates:

According to formula ${\left(q_i\right)}_1=\frac{E_1{h_1}^3({\mathrm{\&gamma;}}_1{h}_1+{\mathrm{\&gamma;}}_2{h}_2+...+{\mathrm{\&gamma;}}_i{h}_i)}{E_1{h_1}^3+E_2{h_2}^3+...+E_i{h_i}^3},$ The formed load of combined influence is carried out to first rock stratum in i the rock stratum that calculating is laid from the bottom to top from first rock stratum, i=1,2 in the formula ... n;

And calculate i rock stratum combined influence carried out when forming load in first rock stratum, to described i+1 rock stratum of laying from the bottom to top from first rock stratum to the formed load (q in first rock stratum _I+1) ₁With i rock stratum to the formed load (q in first rock stratum _i) ₁Carry out difference relatively: when difference relatively draws (q _I+1) ₁＜(q _i) ₁The time, illustrate that absciss layer takes place in i the rock stratum of i+1 rock stratum and its underpart, i=m, and (q at this moment _m) ₁Be described seam roof rock beam institute bearing load, m is positive integer and m＜n;

202, the width higher limit of exploitation band determines that its deterministic process may further comprise the steps:

2021, described top board rock beam is reduced to simply supported beam analysis: and described simply supported beam is the simply supported beam under the evenly distributed load effect; The normal stress at any point A place is on the described simply supported beam M in the formula _xBe the moment of flexure of A place on cross section on the described simply supported beam, y be the A place to the distance of described simply supported beam neutral axis, t is the thickness of described simply supported beam and the thickness sum of m the rock stratum that t=lays from the bottom to top from first rock stratum;

2022, maximum positive pressure stress and maximum draw normal stress to convert: the maximal bending moment M of described simply supported beam _Max=qL ²/ 8, L is the lateral length of described simply supported beam in the formula; The positive pressure stress that bear in upside outward flange place, described simply supported beam middle part is maximum positive pressure stress, the normal stress that draws that bear in downside outward flange place, described simply supported beam middle part is that maximum is drawn normal stress, the downside outer edge at described simply supported beam middle part and upper edge place are equal to t/2 to the distance y of described simply supported beam neutral axis, and described maximum positive pressure stress draws the numerical value of normal stress to equate with maximum and the two is equal to

2023, the actual normal stress that bears of top board rock beam calculates: the actual normal stress that bears of described top board rock beam ${\mathrm{\&sigma;}}_e=\frac{R_l}{F},$ F is safety factor and F=2～4 in the formula, R _lBe the tensile strength of described top board rock beam, described top board rock beam is made up of and j 〉=1 j rock stratum: when j=1, illustrate that described top board rock beam is a rock stratum and R _lTensile strength for this rock stratum; When j＞1, R _lTensile strength average for j rock stratum forming described top board rock beam;

2024, the width higher limit converts: with the σ that calculates in the step 2023 _eFormula in the substitution step 2022 ${\mathrm{\&sigma;}}_{\max }=\frac{3q{L}^2}{t^2},$ Conversion draws the width higher limit of exploitation band $L_{\max }=\sqrt{\frac{4t^2{\mathrm{\&sigma;}}_e}{3q}},$ Q is the (q that calculates in the step 201 in the formula _m) ₁

203, the coal pillar width lower limit is determined, its deterministic process is as follows:

2031, coal column yield region width calculates:

According to formula Calculate coal column yield region width r _p, M is the average height in coal column height and the described coal seam of M=in the formula, and d is the exploitation disturbance factor and d=1.2～3.0, and β is coefficient of horizontal pressure and β=0.25～0.40 at coal column yield region and the interval interface of elastic kernel place, and C is the cohesion of coal seam and top board contact surface,

Be the angle of friction of coal seam and top board contact surface, σ _ZlBe coal column ultimate strength, P _xThe lateral restriction of the rib wherein unit of M is m, C, σ _ZlAnd P _xUnit be MPa; I is influence coefficient and i=3～1.5; Along with the continuous increase of M, i constantly reduces;

2032, the coal pillar width lower limit is determined: according to the coal column yield region width r that calculates in the step 2031 _p, determine the width lower limit D of coal column _Min=2r _p+ r ₀, r wherein ₀Minimum value and r for coal column elastic kernel sector width ₀=0.1m～1m;

Step 3, recovery scheme are determined: according to the L that calculates in the step 2024 _MaxWith the D that calculates in the step 2032 _Min, determine that adopting in the strip coating method recovery process stay yardstick, wherein the width L of the band of exploiting in the strip coating method recovery process ₀≤ L _MaxAnd the width D of the coal column that stays ₀〉=D _Min

Step 4, exploitation: according to conventional band exploitation method described coal seam is exploited, and in the actual recovery process, width of every exploitation is L ₀Band, staying and establishing a width is D ₀Coal column.

2. according to the described a kind of water head site medium and small colliery water-protection coal-mining method of claim 1, it is characterized in that: after described coal seam is exploited according to conventional band exploitation method described in the step 4, forming a plurality of width is L ₀The band goaf, and to be installed with a width between adjacent two described band goafs be D ₀Strip coal pillar; And after according to conventional band exploitation method described coal seam being exploited, also need carry out closely knit filling with inserts respectively to a plurality of described bands goaf from front to back, and a plurality of fill areas of corresponding formation; A plurality of described bands goaf is carried out respectively in the closely knit filling process, from front to back adjacent two described strip coal pillars between the fill area are exploited.

3. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: described coal seam is carried out in the recovery process according to conventional band exploitation method described in the step 4, arrange a plurality of coal mining sections or a plurality of coal-face (3) in described coal seam, between adjacent two coal mining sections or adjacent two coal-faces (3) by being installed with an isolated coal pillar; And after exploitation finished, all forming a plurality of width in each coal mining section or each coal-face (3) was L ₀The district in the band goaf, being installed with a width between the band goaf in adjacent two described districts is D ₀The district in strip coal pillar;

Determine adopting when staying yardstick in the strip coating method recovery process described in the step 3, also need the width minimum value of described isolated coal pillar is determined, in the middle of described isolated coal pillar comprises water proof band and two be laid in respectively described in the middle of water proof band both sides the work plane yield region of exploitation and now exploit the work plane yield region, and the width minimum value deterministic process of described isolated coal pillar is as follows:

Step I, middle water proof bandwidth L ₂₀Calculate: respectively according to side direction hydrostatic pressure coal pillar width design formulas $L_{21}=0.5\mathrm{KM}\sqrt{\frac{3P}{K_P}}$ Or empirical formula $L_{22}=\frac{P}{T_s}+10,$ Water proof bandwidth L in the middle of calculating ₂₁With middle water proof bandwidth L ₂₂, K is safety factor and K=2～5 in the formula, and M is that average height and its unit in described coal seam is m, and P is that head pressure and its unit that middle water proof band that test draws bears is kgf/cm ², K _PFor tensile strength and its unit of coal body in the described coal seam is kgf/cm ², T _sThe water bursting coefficient that calculates for test;

Afterwards, the middle water proof bandwidth L to calculating ₂₁With middle water proof bandwidth L ₂₂Carry out difference relatively: work as L ₂₁〉=L ₂₂The time, middle water proof bandwidth L ₂₀=L ₂₁Otherwise, middle water proof bandwidth L ₂₀=L ₂₂

Step II, isolated coal pillar width minimum value L _MinCalculate:

According to formula L _Min=L ₁+ L ₂₀+ L ₃, calculate the width minimum value of described isolated coal pillar, L in the formula ₁And L ₃Be respectively and exploit work plane yield region width and now exploit work plane yield region width, and L ₁=L ₃The coal column yield region width r that calculates in=the step 2032 _p

According to conventional band exploitation method described coal seam is carried out in the recovery process width L that establishes isolated coal pillar that stays between adjacent two coal mining sections or adjacent two coal-faces (3) in the step 4 _I0〉=L _Min

4. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: the m=1 described in the step 2012, and described seam roof rock beam is first rock stratum; T is the thickness of first rock stratum in the step 2021; L is the lateral length of first rock stratum in the step 2022; The rock beam of top board described in the step 2023 is first rock stratum and R _lTensile strength for first rock stratum.

5. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: before described coal seam is exploited according to conventional band exploitation method described in the step 4, also need according to conventional coal column method for analyzing stability, determined recovery scheme in the employing step 3 is carried out the stability of institute's reserved coal pillar in the band recovery process and analyze.

6. according to the described a kind of water head site medium and small colliery water-protection coal-mining method of claim 5, it is characterized in that: described conventional coal column method for analyzing stability is the equivalent material simulating experiment.

7. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: M=3m～8m in the step 2031.

8. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: in the step 2032 along with described seam roof stability weakens r gradually ₀Increase gradually.

9. according to claim 1 or 2 described a kind of water head site medium and small colliery water-protection coal-mining methods, it is characterized in that: before operational parameter is determined in the step 2, also need definite method of the safe back production upper limit in coal seam routinely, to the safe back production upper limit M in described coal seam _xCalculate, and judge whether to adopt the band exploitation method that described coal seam is exploited according to result of calculation: when the average height M in described coal seam greater than the safe back production that calculates in limited time, then enter step 2 and by the band exploitation method described coal seam exploited; Otherwise, by the broadwall method described coal seam is exploited.

10. according to the described a kind of water head site medium and small colliery water-protection coal-mining method of claim 9, it is characterized in that: to the safe back production upper limit M in described coal seam _xWhen calculating, according to formula $\frac{100M_x}{3.3n_x+3.8}+5.1+\frac{M_x}{n_x}\&le;H_0,$ 5.1 is correction factor in the formula, n _xBe the layering number of plies in described coal seam, H ₀The average height of top, the described coal seam basement rock that draws for test.

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