CN113982581B - Stability control method for overburden seepage isolation zone based on low-carbon mining - Google Patents
Stability control method for overburden seepage isolation zone based on low-carbon mining Download PDFInfo
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Abstract
The invention discloses a stability control method for a overburden seepage isolation zone based on low-carbon mining, and relates to the technical field of coal mining. Firstly, constructing a overburden seepage isolation zone classification system based on the permeability of the seepage isolation zone and a space layer; then, providing a wall type continuous mining and continuous filling working face arrangement mode and mining parameters based on the stability classification control of the seepage isolation belt structure; filling materials capable of keeping stable bearing under the conditions of different working face arrangement modes and mining parameters are selected; and finally, judging whether the seepage isolation zone is broken or not, and if the seepage isolation zone is broken, adjusting wall type continuous mining and continuous charging mining parameters or a working face arrangement mode. The method can realize the in-situ protection of the overlying water body in the ecological fragile mining area, and is beneficial to the construction of ecological mines and green mines.
Description
Technical Field
The invention relates to a stability control method for a overburden seepage isolation zone, in particular to a stability control method for a low-carbon mining-based overburden seepage isolation zone, which is suitable for an overburden seepage isolation zone area.
Background
The amount of the pressed coal under the surface water body and the underground water-bearing layer in China is huge, and how to realize the coordinated development between the safe and efficient exploitation of coal resources and the protection of precious water resources is a problem which needs to be solved urgently at present. At present, researchers mostly take whether a water flowing fractured zone develops to an overlying water-bearing body as a main criterion and criterion for realizing water retention coal mining, and neglect the seepage isolation effect of different overlying rock lithologies and space horizons on the overlying water-bearing body. In order to realize the seepage isolation of the weak seepage isolation belt to the overlying water-containing body, related experts propose and practice coal mining methods such as coordinated mining, overlying strata separation layer grouting, partial mining, goaf filling mining and the like, wherein the goaf filling coal mining method is the most effective way for realizing the seepage isolation of the weak seepage isolation belt to the overlying water-containing body and further realizing water-retaining coal mining. The goaf filling mining is mainly divided into longwall filling mining and roadway filling mining. However, longwall filling mining faces the problems of insufficient filling time and space and mutual limitation of mining and filling, and roadway filling mining faces the problems of low mining efficiency and the like. The modernized mining of mines requires that the water-retaining coal mining technology must simultaneously realize safe and efficient mining and in-situ protection of overlying water bodies.
Disclosure of Invention
Aiming at the prior art, the stability control method of the overburden seepage isolation zone based on low-carbon mining is provided, which has simple steps, combines the advantages of roadway-type jump mining and Wangeviry mining, realizes continuous coal mining and continuous filling, and furthest mines coal resources.
In order to achieve the technical purpose, the stability control method of the overburden seepage isolation zone based on low-carbon mining comprises the following steps:
constructing a overburden seepage isolation zone classification system based on permeability coefficients and space horizons, wherein the overburden seepage isolation zone classification system specifically comprises four types which are combined and divided according to the permeability coefficients and rock strata, three types which are divided according to the horizons according to seepage, and 12 types of overburden seepage isolation zones in total;
step two, according to the type of the current overburden seepage isolation zone, aiming at a working face, implementing a wall type continuous mining continuous filling working face arrangement method based on classification control of the stability of the mining overburden seepage isolation zone, wherein the wall type continuous mining continuous filling working face arrangement method comprises two arrangement methods: firstly, mining and filling a working face by adopting a roadway-type jump mining method, and then mining a Wangeviry block section; or adopting a mode of completely not leaving isolated coal pillars between the Wangeviry mining blocks, and carrying out jump mining filling on the mining blocks;
step three, selecting a filling material meeting the support requirement or adjusting the formula of the filling material according to the wall type continuous mining and continuous filling working face arrangement method selected in the step two;
and step four, judging whether the overburden seepage isolation belt of the current working face is broken under the construction of the selected wall type continuous mining and continuous charging working face arrangement method, if not, continuing to implement the construction, realizing the water resource protective mining, if so, adjusting mining parameters, and if adjusting the mining parameters, still breaking, replacing the working face arrangement mode.
In the first step, the method can be divided into the following steps according to the combination of permeability coefficient and rock stratum: (1) class i vadose isolation zone: single weak rock stratum with permeability coefficient less than 10 -7 m/s; (2) class ii vadose isolation zone: a single hard rock layer, namely a structural key layer, the uniaxial compressive strength is more than 60MPa, and the permeability coefficient is less than 10 -4 m/s; (3) class iii percolation barrier: soft rock and hard rock combination rock strata; (4) class iv seepage barrier: permeability coefficient greater than 10 -1 m/s, the confined expansion rate is more than 40%, and the thickness meets the formula (1).
Wherein gamma is the specific gravity of water; b is i The width of the primary fracture; μ is the dynamic viscosity coefficient of the water body, μ =0.839e at 25 ° -3 Pa · s; delta is the confined expansion ratio; j is hydraulic gradient; theta is the included angle between the primary fracture and the horizontal line of the seepage isolation zone; d is a radical of s Is the fracture spacing; m min The minimum thickness of a IV-class seepage isolation zone;
the four types of seepage isolation zones can be further divided into the following parts according to the layer positions: (1) high-order seepage median: h s >H f (ii) a (2) Median seepage median: h c ≤H s ≤H f (ii) a (3) Low-level seepage median: h s ＜H c (ii) a Wherein H s Is the position of a seepage isolation zone; h c The height of the longwall landing zone; h f The height of the water flowing fractured zone of the long wall is high.
In four types of overburden seepage isolation zones divided according to permeability coefficients and rock stratum combinations, the capacity of realizing seepage isolation of upper water-containing bodies is as follows: class III > class I > class II > class IV; in the three types of overburden seepage isolation zones divided according to the layer positions according to seepage, the capacity of realizing seepage isolation of the water-containing body at the upper part is as follows: high order > medium order > low order.
The class 12 vadose zone is divided into: 4 strong seepage isolation zones, wherein the seepage isolation capability is greater than that of the IV-class seepage isolation zone at the high layer; 5 weak seepage isolation zones, wherein the seepage isolation capability is smaller than that of the IV-class seepage isolation zone at the middle layer; 3 medium seepage isolation zones.
In the second step, the arrangement mode of the wall type continuous mining and continuous filling working face specifically comprises 2 types: (1) aiming at a strong seepage isolation zone, the original Wangeviry mining method is improved, firstly, the original isolation coal pillar (protection block) is mined and filled by adopting a roadway type jump mining method, and then the Wangeviry block (mining block) is mined; and the mining parameters satisfy the formula (2); (2) aiming at the medium and weak seepage isolation zones, the original WangGeviry coal mining method is improved, isolation coal pillars are not left between the WangGeviry mining block sections at all, and jump mining filling is carried out on the mining block sections.
Nd 2 ＜2lsinα+d 1 (2)
Wherein N is the number of the protection block section supporting lanes, N is more than or equal to 1, and N is an integer; d is a radical of 2 The width of a branch roadway for the protection block section; l is the length of the mining block section underground mining; d 1 The length of a branch roadway of the mining block section; alpha is an included angle between a mining block branch roadway and a mining cave.
And in the third step, the critical strength of the filling body for maintaining the bearing stability is obtained according to the stress characteristics of the filling body, and the strength of the filling material needs to meet the formula (3).
Wherein, P max Is the maximum load of the filling body, MPa; h is the coal seam buried depth m; lambda is a safety factor; less than or equal to c The uniaxial compressive strength of the filling body measured in a laboratory is MPa; m is the coal seam mining height M; w is the width of the filling body in the wall type continuous mining and continuous filling, m.
And in the fourth step, judging whether the seepage isolation zone is broken or not by adopting a formula (4).
In the formula (I), the compound is shown in the specification,
maximum tensile stress of the rock stratum of the seepage isolation zone; h s Isolating the thickness of the stratum for seepage>
The maximum bending moment of the rock stratum of the seepage isolation zone is set; />
The tensile stress is allowed for the seepage isolation zone rock stratum.
Aiming at the broken strong seepage isolation zone, adjusting the wall type continuous mining and continuous filling mining parameters: (1) increasing number N of branch lanes of protection block and reducing width d of branch lane of protection block 2 (ii) a (2) Reducing the length l of the Wangeviry mining block section mining cave and the width d of the branch roadway 1 (ii) a (3) Up to Nd 2 ≥2lsinα+d 1 When in use, the working face arrangement mode below the medium seepage intensity is adopted.
Aiming at the broken seepage isolation zone with medium and weak seepage isolation strength, the filling rate of the filling body is continuously improved until full mining and full filling.
Has the advantages that:
on the basis of constructing a classification system of the overburden seepage isolation zone, the method specifically selects different wall type continuous mining continuous filling working face arrangement modes and mining parameters, adopts filling materials to carry out partial filling or non-filling of full mining, and can realize classification cooperative control of the stability of the mining overburden seepage isolation zone while reducing the filling cost to the maximum extent. The seepage isolation zones are divided into 12 types in detail, so that workers can judge according to specific hydrogeological conditions, and mine construction is guided better. The method realizes seepage isolation and in-situ protection of the overlying water-containing body while safely and efficiently liberating the coal briquette under the water-containing body, and is favorable for promoting the construction of ecological mines and green mines.
Drawings
FIG. 1 is a schematic flow chart of a stability control method of a overburden seepage isolation zone based on low-carbon mining, which is disclosed by the invention;
FIG. 2 is a schematic diagram of the arrangement of the wall-type continuous mining and continuous charging working face of the strong seepage isolation zone in the present embodiment;
FIG. 3 is a schematic diagram of the arrangement of the working face of the wall-type continuous mining and continuous filling in the case of low filling rate of the medium and weak seepage isolation zone in this embodiment;
FIG. 4 is a schematic diagram of the arrangement of the wall-type continuous mining continuous-filling working face in the present embodiment when the filling rate of the medium and weak seepage isolation zones is high;
FIG. 5 is a comprehensive geological histogram of a wall-type continuous mining and filling test block in this embodiment.
In the figure: 1-mining a block section underground mining; 2-mining small coal pillars between the block mining chambers; 3-mining block branch roadways; 4-protecting block section branch lane; 5-the mining block section is filled and mined; 6-the mining block is filled with branch roadway.
Detailed Description
The following brief description of the embodiments of the invention is provided in connection with the accompanying drawings:
as shown in figure 1, the stability control method for the overburden seepage isolation zone based on low-carbon mining is characterized by comprising the following steps of:
constructing a overburden seepage isolation zone classification system based on permeability coefficients and space horizons, wherein the overburden seepage isolation zone classification system specifically comprises four types which are combined and divided according to the permeability coefficients and rock strata, three types which are divided according to the horizons according to seepage, and 12 types of overburden seepage isolation zones in total;
the permeability coefficient and the formation composition can be divided into: (1) class i vadose isolation zone: single weak rock stratum with permeability coefficient less than 10 -7 m/s; (2) class ii vadose isolation zone: a single hard rock layer, namely a structural key layer, the uniaxial compressive strength is more than 60MPa, and the permeability coefficient is less than 10 -4 m/s; (3) class iii percolation barrier: soft rock and hard rock combination rock strata; (4) class iv seepage barrier: permeability coefficient greater than 10 -1 m/s, the confined expansion rate is more than 40%, and the thickness meets the formula (1).
Wherein gamma is the specific gravity of water; b i The width of the primary fracture; μ is the dynamic viscosity coefficient of the water body, μ =0.839e at 25 ° -3 Pa · s; delta is the confined expansion ratio; j is hydraulic gradient; theta is the included angle between the primary fracture and the horizontal line of the seepage isolation zone; d is a radical of s Is the fracture spacing; m is a group of min The minimum thickness of the IV-class seepage isolation zone;
the four seepage isolation zones can be divided into the following parts according to the layer positions: (1) high-order seepage median: h s ＞H f (ii) a (2) Median seepage median: h c ≤H s ≤H f (ii) a (3) Low-level seepage isolation zone: h s ＜H c (ii) a Wherein H s Is a seepage isolation zone layer position; h c The height of the longwall landing zone; h f The height of the longwall water-flowing fractured zone is high;
in four types of overburden seepage isolation zones divided according to permeability coefficients and rock stratum combinations, the capacity of realizing seepage isolation of upper water-containing bodies is as follows: class III > class I > class II > class IV; in the three types of overburden seepage isolation zones divided according to the layer positions according to seepage, the capacity of realizing seepage isolation of the water-containing body at the upper part is as follows: high order > middle order > low order;
the class 12 vadose zone is divided into: 4 strong seepage isolation zones, wherein the seepage isolation capability is greater than that of the IV-class seepage isolation zone at the high layer; 5 weak seepage isolation zones, wherein the seepage isolation capability is smaller than that of the IV-class seepage isolation zone at the middle layer; 3 medium seepage isolation zones;
step two, according to the type of the current overburden seepage isolation zone, aiming at a working face, implementing a wall type continuous mining continuous filling working face arrangement method based on classification control of the stability of the mining overburden seepage isolation zone, wherein the wall type continuous mining continuous filling working face arrangement method comprises two arrangement methods: firstly, mining and filling a working face by adopting a roadway-type jump mining method, and then mining a Wangeviry block section; or adopting a mode of completely not leaving isolated coal pillars between the Wangeviry mining blocks, and carrying out jump mining filling on the mining blocks;
the arrangement mode of the wall type continuous mining and continuous charging working face specifically comprises 2 types: (1) aiming at a strong seepage isolation zone, the original WangVeili mining method is improved, the original isolation coal pillar (protective block) is mined and filled by adopting a roadway jump mining method, and then the WangVeili block (mining block) is mined; and the mining parameters satisfy the formula (2); (2) aiming at medium and weak seepage isolation zones, the original WangVeili coal mining method is improved, isolation coal pillars are not left between WangVeili mining blocks, and jumping mining filling is carried out on the mining blocks.
Nd 2 ＜2lsinα+d 1 (2)
Wherein N is the number of the protection block section supporting lanes, N is more than or equal to 1, and N is an integer; d 2 The width of the branch lane 4 for the protection block section; l is the length of the mining block section underground mining 1; d 1 The length of the branch roadway 3 for the mining block section; alpha is an included angle between the mining block branch roadway 3 and the mining block underground mining 1;
step three, selecting a filling material meeting the support requirement or adjusting the formula of the filling material according to the wall type continuous mining and continuous filling working face arrangement method selected in the step two;
obtaining the critical strength of the filling body for maintaining the bearing stability according to the stress characteristics of the filling body, wherein the strength of the filling material needs to meet the formula (3):
wherein, P max Is the maximum load of the filling body; h is the coal seam burial depth; lambda is a safety factor; sigma c The uniaxial compressive strength of the filling body measured in a laboratory is MPa; m is the coal seam mining height; w is the width of the filling body in the wall type continuous mining and continuous filling process;
step four, judging whether the overburden seepage isolation zone of the current working face is broken under the construction of the selected wall type continuous mining and continuous charging working face arrangement method, if not, continuing to implement to realize water resource protective mining, if so, adjusting mining parameters, and if adjusting mining parameters, still breaking, replacing the working face arrangement mode;
judging whether the seepage isolation zone is broken or not by adopting a formula (4):
in the formula (I), the compound is shown in the specification,
maximum tensile stress of the rock stratum of the seepage isolation zone; h s Isolating the thickness of the stratum for seepage>
The maximum bending moment of the rock stratum of the seepage isolation zone is set; />
Allowing tensile stress for the formation of the seepage isolation zone.
Aiming at the broken strong seepage isolation zone, adjusting the wall type continuous mining and continuous filling mining parameters: (1) increasing the number N of the branch lanes of the protection block and reducing the width d of the branch lane 4 of the protection block 2 (ii) a (2) Increasing the width of the small coal pillar 2 between the mining block sections and the drift, and simultaneously reducing the length l of the Wangeviry mining block section drift 1 and the width d of the mining block section branch drift 3 1 (ii) a (3) Up to Nd 2 ≥2lsinα+d 1 When in use, the working face arrangement mode below the medium seepage intensity is adopted.
Aiming at the seepage isolation zone with the breaking medium and weak seepage isolation strength and below, the filling rate of the filling body is continuously improved until the full-mining and full-filling are carried out.
The first embodiment,
A flow chart of a stability control method of a overburden seepage isolation zone based on low-carbon mining is known, and the cooperative control method mainly comprises the following steps:
firstly, constructing a overburden seepage isolation zone classification system based on permeability coefficients and a space horizon. Overburden vadose zones can be classified into 12 categories. According to the combination of permeability coefficient and rock stratum, the method can be divided into: (1) class i vadose zone: single weak rock stratum with permeability coefficient less than 10 -7 m/s; (2) class ii vadose isolation zone: single hard rock stratum (structural key layer), uniaxial compressive strength of more than 60MPa and permeability coefficient of less than 10 -4 m/s; (3) class iii percolation barrier: soft rock and hard rock combination rock strata; (4) class iv seepage barrier: permeability coefficient greater than 10 -1 m/s, the confined expansion rate is more than 40%, and the thickness meets the formula (1).
Wherein gamma is the specific gravity of water; b i Is the native fracture width, m; mu is the dynamic viscosity coefficient of the water body (mu =0.839e at 25 DEG) -3 Pa · s); δ is the confined expansion ratio,%; j is hydraulic gradient; theta is the included angle between the primary crack and the horizontal line of the seepage isolation zone; d s Is the crack spacing, m; m is a group of min The minimum thickness of the IV-type seepage isolation zone is m.
The capacity of realizing seepage isolation of the upper water-containing body is as follows: class III > class I > class II > class IV.
The above 4 kinds of seepage isolation zones can be divided into: (1) high-order seepage median: h s ＞H f (ii) a (2) Median seepage median barrier zone: h c ≤H s ≤H f (ii) a (3) Low-level seepage median: h s ＜H c . See in particular the table below.
Wherein H s Representing a seepage isolation zone horizon; sigma M represents the cumulative mining height
The capacity of realizing seepage isolation of the upper water-containing body is as follows: high order > medium order > low order.
The above class 12 vadose isolation zone can be roughly divided into: (1) 4 strong seepage isolation zones (the seepage isolation capability is greater than that of the high-level IV-class seepage isolation zone), 5 weak seepage isolation zones (the seepage isolation capability is less than that of the medium-level IV-class seepage isolation zone) and 3 medium seepage isolation zones.
Secondly, providing a wall type continuous mining and continuous filling working surface cloth based on classification control of stability of mining overburden seepage isolation belt structureThe method is as follows. The arrangement mode of the wall type continuous mining and continuous charging working face comprises 2 types: (1) aiming at a strong seepage isolation zone, as shown in figure 2, the original Wangeviri mining method is improved, the original isolation coal pillar (a protection block section is filled into a branch roadway) is mined and filled by adopting a roadway type jump mining method, and the number of the protection block section is B 1 ，B 2 ，…，B n And then mining the Wangeviry block (mining block) with the number of the mining block being M 1 ，M 2 ，…，M n (ii) a And the mining parameters satisfy the formula (2):
Nd 2 ＜2lsinα+d 1 (2)
wherein N is the number of the protection block section supporting lanes (N is not less than 1 and is an integer), and N is an integer; d is a radical of 2 The width m of the protection block section branch lane 4; l is the length of the mining block section underground mining 1, m; d 1 The length of the mining block branch roadway 3 is m; alpha is the included angle between the mining block branch roadway 3 and the mining block underground mining 1.
As shown in FIG. 3, for medium and weak percolation barrier zones, the width of the protection block needs to be increased because the percolation barrier zone is weaker than the strong percolation barrier zone, and when the width of the protection block is greater than or equal to the width of the mining block, namely Nd 2 ≥2lsinα+d 1 And meanwhile, the original WangGeviry coal mining method is improved, the protection block sections are completely replaced by WangGeviry mining block sections, and isolation coal pillars are not left between the mining block sections. At this point the entire mining area has n Wangeviry mining segments in total, labeled M 1 ，M 2 ，…，M n Jumping mining is carried out on the mining block section, and the mining block section mining cave 1 and the mining block section branch roadway 3 of the (2 m-1) th Wangeviry block section after mining are filled to form a mining block section filled mining cave 5 and a mining block section filled branch roadway 6, and the 2m mining block section mining cave 1 and the mining block section branch roadway 3 are not filled.
As shown in FIG. 4, if the water blocking capability of the seepage isolation is further weakened, the (3 m-2) th and (3 m-1) th mining blocks are filled, and the 3m mining block is not filled, wherein m is an integer and n is more than or equal to 1 and less than or equal to n/3,n is a multiple of 3. Obviously, for the seepage isolation zone with the weakest seepage isolation capability, all the Wangweili mining blocks need to be fully mined and fully charged.
And thirdly, selecting filling materials under different mining and filling conditions, and specifically comprising the following steps: (1) obtaining the critical strength of the filling body for maintaining the bearing stability according to the stress characteristics of the filling body; (2) selecting the filling material to obtain laboratory uniaxial compressive strength sigma of the filling material c And maximum load P of the packing body max Satisfying formula (3).
Wherein, P max Is the maximum load of the filling body, MPa; h is the coal seam buried depth m; lambda is a safety factor; sigma c The uniaxial compressive strength of the filling body measured in a laboratory is MPa; m is the coal seam mining height M; w is the width of the filling body in the wall type continuous mining and continuous filling, m.
And fourthly, judging whether the overburden seepage isolation belt is broken under the conditions of different working face arrangement modes by adopting a formula (4).
In the formula (I), the compound is shown in the specification,
maximum tensile stress of the rock stratum of the seepage isolation zone; h s Isolating the thickness of the stratum for seepage>
The maximum bending moment of the rock stratum of the seepage isolation zone is set; />
Allowing tensile stress for the formation of the seepage isolation zone.
Further, aiming at the broken strong seepage isolation belt, adjusting the wall type continuous mining and continuous filling mining parameters: (1) increasing the number N of the supporting lanes of the protection block section and reducing the width d of the supporting lanes 4 of the protection block section 2 (ii) a (2) Increasing the width of the small coal pillar 2 between the mining block mining caves, and simultaneously reducing the length l and the opening of the Wangeviry mining block mining cave 1Width d of block section branch lane 3 1 (ii) a (3) Up to Nd 2 ≥2lsinα+d 1 When in use, the working face arrangement mode below the medium seepage intensity is adopted.
Furthermore, aiming at the broken medium and weak seepage isolation zones, the filling rate of the filling body is continuously improved until full mining and full filling.
Example 1: this example takes a particular mine in Shanxi. The main mining coal seam is 15 coal, the coal seam thickness is 2.5m, the inclination angle is 1-3 degrees, as shown in figure 5, the average burial depth of the coal seam is 250m, different layers of the upper part of a mining block section are provided with a sandstone aquifer (I) and a sandstone aquifer (II), and the lower parts of the two aquifers are provided with III-type seepage isolation zones. If water-retaining coal mining is to be realized, the seepage isolation of the lower seepage isolation zone to the aquifer (II) must be ensured, and the distance between the lower overburden seepage isolation zone and the coal seam roof is 16m. The covering rock of the mining block section mainly comprises fine sandstone, sandy mudstone, limestone and the like, and the integral lithology of the covering rock is medium-hard. The height of the longwall caving zone is 17.5m and the height of the water-flowing fractured zone is 41.6m. According to the classification system standard of the seepage isolation zone, the III-class seepage isolation zone close to the coal bed belongs to a weak seepage isolation zone. The pressed coal under water is liberated by adopting the arrangement mode of a wall type continuous mining and continuous filling working face as shown in figure 4. The length of the mining block section underground mining is 10m, the width of the branch roadway is 5.5m, the included angle alpha between the branch roadway and the underground mining is 40 degrees, and the full mining and full filling are realized. The average length of the mining block is 340m, and the width of the mining block is about 150m. According to the subordinate area method and the Sheorey coal pillar strength calculation formula, the bearing stability of the filling body can be ensured when the strength and the stress of the filling body meet the formula (5):
wherein gamma is the average unit weight of overlying strata, and 2.5 × 10 is adopted -2 MPa/m, H is the coal seam buried depth, 250m is taken, lambda is the safety coefficient, 2.7, sigma is taken c The uniaxial compressive strength of the filling body measured in a laboratory, wherein M is the coal seam mining height, 2.5m, W =4lsin alpha +2d is taken 1 And the minimum uniaxial compressive strength of the filling body measured in a laboratory must be more than 1.4MPa by = 4X 10 xsin 35 DEG + 2X 5.5=33.8 m. Selecting the filling material according to the key mechanical parameter indexAnd (5) feeding.
And (3) establishing a mining overburden rock deformation elastic foundation beam mechanical model according to the wall type continuous mining and continuous filling working face arrangement mode shown in the figure 4 to obtain a roof arbitrary rock stratum deflection formula. Calculating the maximum tensile stress of the lower III-class seepage isolation zone (weak seepage isolation zone) according to a deflection formula
The condition sufficient for the structural stability of the seepage isolation belt is ^ 5>
And (3) bringing specific values into the lower III-class seepage isolation zone, so that the thin sandstone stratum with the thickness of 37m at the lower part of the isolation zone is not broken, and the seepage isolation zone still has a seepage isolation effect on the aquifer (II) at the upper part of the isolation zone.
Claims (3)
1. A stability control method for a overburden seepage isolation zone based on low-carbon mining is characterized by comprising the following steps:
constructing a overburden seepage isolation zone classification system based on permeability coefficients and space layers, wherein the overburden seepage isolation zone classification system specifically comprises four types which are divided according to the combination of the permeability coefficients and rock strata, three types which are divided according to seepage and layers, and 12 types of overburden seepage isolation zones in total;
step two, according to the current type of the overburden seepage isolation zone, aiming at a working face, implementing a wall type continuous mining and continuous filling working face arrangement method based on classification control of the stability of the mining overburden seepage isolation zone structure, wherein the wall type continuous mining and continuous filling working face arrangement method comprises two arrangement methods: firstly, mining and filling a working face by adopting a roadway-type jump mining method, and then mining a Wangeviry block section; or adopting a mode of completely not leaving isolated coal pillars between the Wangeviry mining blocks, and carrying out jump mining filling on the mining blocks;
step three, selecting a filling material meeting the support requirement or adjusting the formula of the filling material according to the wall type continuous mining and continuous filling working face arrangement method selected in the step two;
judging whether the overburden seepage isolation belt of the current working face is broken under the construction of the selected wall type continuous mining and continuous charging working face arrangement method, if not, continuing to implement to realize the water resource protective mining, if so, adjusting mining parameters, and if adjusting the mining parameters, still breaking, replacing the working face arrangement mode;
in the first step, the method can be divided into the following steps according to the combination of permeability coefficient and rock stratum: (1) class i vadose isolation zone: single weak rock stratum with permeability coefficient less than 10 -7 m/s; (2) class ii vadose isolation zone: a single hard rock layer, namely a structural key layer, the uniaxial compressive strength is more than 60MPa, and the permeability coefficient is less than 10 -4 m/s; (3) class iii percolation barrier: soft rock and hard rock combination rock strata; (4) class iv seepage barrier: permeability coefficient greater than 10 -1 m/s, the confined expansion rate is more than 40 percent, and the thickness meets the formula (1),
wherein gamma is the specific gravity of water; b is i The width of the primary fracture; μ is the dynamic viscosity coefficient of the water body, μ =0.839e at 25 ° -3 Pa · s; delta is the confined expansion ratio; j is hydraulic gradient; theta is an included angle between the primary fracture and the horizontal line of the seepage isolation zone; d s Is the fracture spacing; m min The minimum thickness of the IV-class seepage isolation zone;
the four types of seepage isolation zones can be further divided into the following parts according to the layer positions: (1) high-order seepage flow median: h s >H f (ii) a (2) Median seepage median barrier zone: h c ≤H s ≤H f (ii) a (3) Low-level seepage median: h s <H c (ii) a Wherein H s Is the position of a seepage isolation zone; h c The height of the longwall span-fall belt is set; h f The height of the longwall water-flowing fractured zone is high;
in four types of overburden seepage isolation zones divided according to permeability coefficients and rock stratum combinations, the capacity of realizing seepage isolation of upper water-containing bodies is as follows: class III > class I > class II > class IV; according to three types of overburden seepage isolation zones divided according to the layer position by seepage, the seepage isolation capability of the water-containing body on the upper part is realized as follows: high order > medium order > low order;
the class 12 vadose zone is divided into: 4 strong seepage isolation zones, wherein the seepage isolation capability is greater than that of the IV-class seepage isolation zone at the high layer; 5 weak seepage isolation zones, wherein the seepage isolation capability is smaller than that of the IV-class seepage isolation zone at the middle layer; 3 medium-seepage isolation zones are arranged on the upper surface of the body,
in the second step, the arrangement mode of the wall type continuous mining and continuous charging working face specifically comprises 2 types: (1) aiming at a strong seepage isolation zone, the original Wangeviry mining method is improved, firstly, the original isolation coal pillar, namely a protection block section, is mined and filled by adopting a roadway type jump mining method, and then the Wangeviry block section is mined, namely a mining block section; and the mining parameters satisfy the formula (2); (2) aiming at the medium and weak seepage isolation zones, the original WangGeviry coal mining method is improved, isolation coal pillars are not left between the WangGeviry mining block sections at all, the jumping mining filling is carried out on the mining block sections,
Nd 2 <2lsinα+d 1 (2)
wherein N is the number of the protection block section supporting lanes, N is more than or equal to 1, and N is an integer; d 2 The width of a branch roadway of the protective block section; l is the length of the mining block section underground mining; d 1 The length of a branch roadway of the mining block section; alpha is an included angle between a mining block branch roadway and a mining cave.
2. The overburden seepage isolation zone stability control method based on low carbon mining as claimed in claim 1, wherein in step three: obtaining the critical strength of the filling body for maintaining the bearing stability according to the stress characteristics of the filling body, wherein the strength of the filling material needs to satisfy a formula (3),
wherein, P max Is the maximum load of the filling body, MPa; h is the coal seam buried depth m; lambda is a safety factor; sigma c The uniaxial compressive strength of the filling body measured in a laboratory is MPa; m is the coal seam mining height M; w is the width of the filling body in the wall type continuous mining and continuous filling, m.
3. The overburden seepage isolation zone stability control method based on low carbon mining of claim 1, wherein in the fourth step: judging whether the seepage isolation zone is broken or not by adopting a formula (4),
in the formula (I), the compound is shown in the specification,
maximum tensile stress of the rock stratum of the seepage isolation zone; h sh For the thickness of the formation in the vadose zone>
The maximum bending moment of the rock stratum of the seepage isolation zone is set; />
Allowable tensile stress for the rock stratum of the seepage isolation zone;
aiming at the broken strong seepage isolation zone, adjusting the wall type continuous mining and continuous filling mining parameters: (1) increasing number N of branch lanes of protection block and reducing width d of branch lane of protection block 2 (ii) a (2) Reducing the length l of the Wangeviry mining block section mining cave and the width d of the branch roadway 1 (ii) a (3) Up to Nd 2 ≥2lsinα+d 1 When in use, a working surface arrangement mode below the medium seepage intensity is adopted;
aiming at the broken seepage isolation zone with medium and weak seepage isolation strength, the filling rate of the filling body is continuously improved until full mining and full filling.
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