CN112668144B - Prediction method of surface subsidence caused by mining of thick topsoil and thin bedrock - Google Patents

Prediction method of surface subsidence caused by mining of thick topsoil and thin bedrock Download PDF

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CN112668144B
CN112668144B CN202011380965.XA CN202011380965A CN112668144B CN 112668144 B CN112668144 B CN 112668144B CN 202011380965 A CN202011380965 A CN 202011380965A CN 112668144 B CN112668144 B CN 112668144B
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subsidence
hydrophobic
bottom aquifer
aquifer
mining
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程桦
彭世龙
姚直书
王晓健
余大有
张亮亮
薛维培
李华
秦志强
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NO 1 SURVEYING TEAM OF ANHUI CHARCOAL FIELD AND GEOLOGY BUREAU
Anhui University of Science and Technology
Anhui Jianzhu University
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NO 1 SURVEYING TEAM OF ANHUI CHARCOAL FIELD AND GEOLOGY BUREAU
Anhui University of Science and Technology
Anhui Jianzhu University
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Abstract

The invention provides a prediction method of surface subsidence caused by mining thick surface soil and thin bedrock, which comprises the following steps from the surface to the bottom: a thick overburden, a thin basement and a coal seam, the prediction method comprising the steps of: 1) establishing a prediction model of surface subsidence caused by coal mining; 2) establishing a prediction model of surface subsidence caused by hydrophobic consolidation of a bottom aquifer; 3) and linearly overlapping the subsidence of the surface subsidence caused by coal mining and the hydrophobic consolidation of the bottom aquifer to obtain a prediction model of the subsidence of the surface subsidence caused by the mining of the thick-surface soil thin bedrock. According to the prediction method, the water-soil coupling effect generated by the influence of coal mining activities on the thick surface soil layer is considered in stratum settlement deformation, and through the solution of a settlement source function and a settlement propagation distribution function, an expression of the surface subsidence amount when the bottom water-bearing stratum is subjected to hydrophobic settlement is obtained, so that a thick surface soil and thin bedrock mining subsidence prediction model and a prediction method thereof are established.

Description

Prediction method for surface subsidence caused by mining of thick surface soil and thin bedrock
Technical Field
The invention relates to the field of coal mining, in particular to a prediction method of surface subsidence caused by mining of thick surface soil and thin bedrock.
Background
In recent years, as the coal resources of China gradually enter deep mining, the occurrence conditions of thick surface soil and thin bedrock generally appear in the coal resources of Huang-Huai region. According to analysis of a large amount of observation data, the surface subsidence coefficient caused by coal mining activity under thick surface soil and thin bedrock is obviously larger, and the condition that part of mining areas are even larger than 1 occurs; the surface subsidence and horizontal movement range extend far relative to the mining area; deep mines are extremely easy to damage in thick surface soil sections, and the phenomena cannot be reasonably explained according to the conventional mining subsidence theory. The reason is that previous researches are limited to the influence of single coal seam mining on surface subsidence, although some researchers also consider the difference between deformation of a surface soil layer and deformation of a bedrock layer, the researches only distinguish and process the surface soil layer and the bedrock from parameter selection, influence of coal mining activities on the surface soil layer is not considered, water and soil coupling effect generated in the subsidence deformation process of the surface soil layer is not considered, and the characteristics of various media and multi-field coupling effect of thick surface soil and thin bedrock are ignored.
Research and analysis show that along with the mass exploitation of coal resources under thick surface soil and thin bedrock, a large amount of dredging and dropping of bottom water content through a bedrock water flowing fracture zone, the water level is obviously reduced, secondary consolidation and sedimentation occur, and the additional sedimentation and deformation of the ground surface caused by the hydrophobic sedimentation of the bottom water content due to the coal mining effect cannot be ignored. Considering that the bottom aquifer of the thick topsoil belongs to a confined aquifer, the hydrophobic consolidation settlement characteristics of the bottom aquifer are obviously different from the hydrophobicity of the shallow diving stratum. At present, a subsidence prediction model and a prediction method are not available in the aspect of research on the mechanism of stratum subsidence under the combined action of mining of a thick-surface soil thin bedrock coal bed and hydrophobic settlement of confined water at the bottom.
Disclosure of Invention
The invention aims to provide a prediction method of surface subsidence caused by thick surface soil and thin bedrock mining, which can reveal the mining subsidence rule of the thick surface soil and the thin bedrock and the intrinsic mechanism thereof to guide coal mining, is used for preventing and controlling a coal mining subsidence area and ensuring the safety of buildings (structures) in a near mining area, establishes a thick surface soil and thin bedrock mining subsidence prediction model and forms the prediction method.
In order to achieve the above purpose, the invention provides the following technical scheme:
a prediction method for surface subsidence caused by mining of thick surface soil and thin bedrock comprises the following steps from the surface to the bottom: the high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-; a solid-liquid two-phase random medium with solid-phase soil particles and confined water is arranged in the bottom water-containing layer; the surface subsidence of the thick surface soil and the thin bedrock is jointly initiated by coal seam mining and hydrophobic consolidation of a bottom aquifer, wherein the prediction method comprises the following steps:
1) establishing a prediction model of surface subsidence caused by coal mining
Any coal bed unit d xi under the condition of a two-dimensional coordinate system2dη2Mining induced subsidence W of arbitrary point A (x, y) of the earth's surfacece(x) Comprises the following steps:
Figure BDA0002808450920000021
r: the radius of influence of coal seam mining on surface subsidence; d xi2: the horizontal dimension of the coal seam unit; d eta2: the vertical dimension of the coal seam unit;
extending the two-dimensional coordinates into a three-dimensional coordinate system, if the coal seam is horizontal, the coal seam coordinate system o2、ξ2、
Figure BDA0002808450920000022
The horizontal projection of the horizontal projection is coincident with the o, x and y horizontal projections of the earth surface coordinate system, so that the coal bed unit
Figure BDA0002808450920000023
Is used to induce subsidence W at any point A (x, y) of the earth's surfacece(x, y) is:
Figure BDA0002808450920000024
in the inclined coal seam, the maximum sinking amount of the coal seam roof is W0Then over the entire mining range omega2The subsidence of any point A (x, y) on the earth surface caused by inner mining is as follows:
Figure BDA0002808450920000025
2) establishing a prediction model of surface subsidence caused by hydrophobic consolidation of a bottom aquifer
The subsidence S (x, y, z) of any point of the earth surface caused by hydrophobic consolidation of the bottom aquifer can be determined by a subsidence source function
Figure BDA0002808450920000026
And sink propagation distribution function
Figure BDA0002808450920000027
Expressed as:
Figure BDA0002808450920000028
wherein omega1Is a hydrophobic area of a bottom aquifer;
3) and linearly overlapping the subsidence of the surface subsidence caused by coal mining and the hydrophobic consolidation of the bottom aquifer to obtain a prediction model of the subsidence of the surface subsidence caused by the mining of the thick-surface soil thin bedrock.
Further, in the above prediction method, in the step 2), the sink source function is determined according to the sink source function
Figure BDA0002808450920000031
Calculating to obtain the three-dimensional unit of the bottom aquifer
Figure BDA0002808450920000032
The amount of compression set ds due to drainage is located at depth (H-eta) in the two-dimensional coordinate system before the bottom aquifer is drained1) D xi of plane unit1dη1The effective stress between solid-phase soil particles is sigma, and the following calculation formula is satisfied:
σ＝(H-M)γ0+(M-η1)γf-(h-η1)γwformula 5
Wherein eta is1: the distance from any plane unit in the bottom water-containing layer to the bottom of the bottom water-containing layer; gamma ray0: average bulk density, kN/m, of all the earth above the bottom aquifer3；γf: volume weight of saturated soil body in pressure water in bottom water-bearing stratum, kN/m3；γw: volume weight of pressure-bearing pore water in bottom water-containing layer, kN/m3(ii) a h: the height of an initial water head of each point of the bottom aquifer; h: the thickness of the thick topsoil layer; m: the thickness of the bottom aquifer; d xi1: a horizontal dimension of the planar unit; d eta1: a vertical dimension of the planar unit;
the bottom of the bottom aquifer is hydrophobic, the height of the initial water head is reduced by delta h, and the total stress of the overlying surface soil layer is kept constant, so that the pores are formedThe part of the water pressure reduction is converted into solid-phase soil particles to bear, so the depth (H-eta) in the bottom water-containing layer1) D xi plane unit1dη1The effective stress increase of (a) is:
Figure BDA0002808450920000033
the depth (H-eta) can be obtained by the compaction coefficient formula and consolidation formula of the soil1) D xi of plane unit1dη1At effective stress increment
Figure BDA0002808450920000034
The compression deformation ds generated under the action of the compression function is the sinking source function of the bottom aquifer plane unit
Figure BDA0002808450920000035
Figure BDA0002808450920000036
Wherein e is0: an initial void ratio of the bottom aquifer; cc: a compressibility index of the bottom aquifer.
Further, in the above prediction method, in the step 2), the sinking source function is determined according to the sinking source function
Figure BDA0002808450920000037
And calculating to obtain the compression deformation ds generated by the hydrophobic property of the bottom aquifer, and calculating to obtain the amount of the surface subsidence caused by the hydrophobic subsidence of the bottom aquifer from the subsidence propagation distribution function, namely:
Figure BDA0002808450920000038
wherein, Wwe(x) Is the amount of surface subsidence, r (eta), caused by the hydrophobic settlement of any plane unit1) Is eta1The main influence range of the hydrophobic settlement of the bottom aquifer on the earth surface on the level;
radius range-R of hydrophobic consolidation influence throughout the bottom aquiferw～+RwIn addition, any hydrophobic consolidation of planar units produces a small volume compression d xi1ds, ultimate subsidence W of the surface due to hydrophobic consolidation of the bottom aquiferw(x) I.e. the plane unit d xi1dη1Superposition of the effects:
Figure BDA0002808450920000041
the two-dimensional coordinate system is expanded into a three-dimensional coordinate system, and a hydrophobic settlement coordinate system xi of the bottom aquifer1、o1、
Figure BDA0002808450920000042
The horizontal projection of the X, O and Y coordinate system coincides with the subsidence W of the X direction of the earth surfacewe(x) And y-direction sinkage Wwe(y) are respectively:
Figure BDA0002808450920000043
then the bottom aquifer eta1A certain three-dimensional unit at the horizontal position
Figure BDA0002808450920000044
The hydrophobic consolidation of (a) initiates the subsidence W of any point A (x, y) of the earth's surfacewe(x, y) may be represented as:
Figure BDA0002808450920000045
then at the top of the bottom aquifer, eta1M with the bottom of the bottom hydrous layer, eta1Radius range of influence of hydrophobic consolidation of the entire bottom aquifer between-0-Rw～+RwIn that any three-dimensional unit generates a slight volume compression
Figure BDA0002808450920000046
Final subsidence W of earth surface caused by hydrophobic consolidation of bottom aquiferw(x, y) is the superposition of the effects of the above infinitesimal bodies:
Figure BDA0002808450920000047
further, in the above prediction method, in the step 3), the coal seam mining and the hydrophobic consolidation of the bottom aquifer both induce surface subsidence, and the coal seam mining and the surface subsidence induced by the hydrophobic consolidation of the bottom aquifer are independent of each other, and then the final amount of subsidence of the surface subsidence can be expressed as a result of linear superposition of the surface subsidence induced by the coal seam mining and the surface subsidence induced by the hydrophobic consolidation of the bottom aquifer:
W(x,y)＝Wc(x,y)+Ww(x, y) formula 13.
Further, in the above prediction method, before the step 1), a preparation step is further included, and the preparation step specifically includes performing hole drilling coring on the thin bedrock layer and the thick overburden layer from the earth surface, and determining the thickness H of the thin bedrock1The thickness H of the thick surface soil layer and the thickness M of the bottom water-bearing layer, and carrying out a mechanical test on the cored sample to test the average volume weight gamma of all the stratum soil bodies above the bottom water-bearing layer0And the volume weight gamma of the saturated soil body in the pressure water in the bottom aquiferfCompression index C of the bottom aquifercTo initial pore ratio e0(ii) a Monitoring the water level change of the water-bearing stratum at the bottom before and after the coal seam is mined and in the mining process; according to the water level change of the bottom water-bearing stratum, determining an initial water level h before hydrophobic sedimentation of the bottom water-bearing stratum and a stable water level f (xi) after hydrophobic sedimentation of the bottom water-bearing stratum1) (ii) a Calculating a water level drop value according to the water level change of different positions of the bottom water-bearing stratum: Δ h ═ h-f (ξ)1)。
Further, in the above prediction methodProjecting and coinciding the centers of the surface subsidence, the coal seam mining center and the bottom aquifer water-drainage consolidation center on a surface water plane, and establishing a prediction model by adopting a unified coordinate system, wherein the unified coordinate system comprises three coordinate systems of a surface subsidence coordinate system, a coal seam mining coordinate system and a bottom aquifer water-drainage consolidation coordinate system, and the three coordinate systems have the same scale, wherein the surface subsidence coordinate system selects a surface point O which is directly above the center of a goaf as an origin of a horizontal axis x, and the direction of the coal seam from the origin along the horizontal plane is the positive direction of the x axis; an arbitrary point subsidence value W (x) with a surface abscissa of x and a horizontal movement value u (x) are respectively vertically downward and vertically upward from an origin O; the coordinate origin of the bottom aquifer hydrophobic consolidation coordinate system is positioned at the bottom O of the bottom aquifer right above the midpoint of the bottom plate of the run-to goaf1On the abscissa xi1The same direction as the x-axis, the ordinate η1Vertically upwards; the origin of coordinates of the coal seam mining coordinate system is in the middle point O of the bottom plate of the run-out goaf2On the abscissa xi2The same direction as the x-axis, the ordinate η2Vertically upwards.
Further, in the prediction method, the coal seam mining-induced surface subsidence satisfies a traditional probability integration method subsidence model, follows a linear superposition principle, and moves stably due to the coal seam mining-induced surface subsidence volume VSink 2Equal to coal production volume VCoal miningI.e. VSink 2＝VCoal mining(ii) a The bottom aquifer in the hydrophobic consolidation of the bottom aquifer is a confined aquifer, pores in the bottom aquifer are filled with confined water, solid-phase soil particles and confined water in the pores are incompressible and can be regarded as a horizontal homogeneous and isotropic solid-liquid two-phase random medium, and the upper topsoil layer obeys the random medium theory in the hydrophobic consolidation sinking process of the bottom aquifer; the bottom water-bearing layer is a semi-infinite space body, the pore compression caused by hydrophobic consolidation of the bottom water-bearing layer only occurs along the vertical direction, and the compression property of the same kind of soil does not change along with the depth.
Further, in the prediction method, the bottom aquifer belongs to a confined aquifer, the bottom aquifer is hydrophobic to form a virtual falling funnel, the whole bottom aquifer is filled with confined water, the whole bottom aquifer sinks due to hydrophobic consolidation within the influence range of the hydrophobic consolidation, and the stratum compression caused by the hydrophobic consolidation within the virtual falling funnel range of the bottom aquifer is regarded as thickening exploitation.
The analysis shows that the prediction method of the surface subsidence caused by the thick surface soil and the thin bedrock provided by the invention starts from the geological mining characteristics of the thick surface soil and the thin bedrock and the characteristics of various media and multi-field coupling action, considers the water-soil coupling action generated by the thick surface soil layer influenced by coal mining activity into the stratum subsidence deformation, obtains the surface subsidence expression when the bottom water-bearing layer is hydrophobic and subsides through the solution of a subsidence source function and a subsidence propagation distribution function, further establishes the prediction model of the surface subsidence caused by the thick surface soil and the thin bedrock and the prediction method thereof, fills the blank that the surface subsidence prediction model and the prediction method caused by the coal mining and the hydrophobic subsidence of the confined pore water of the bottom water-bearing layer under the geological mining conditions of the thick surface soil and the thin bedrock are not considered at present, and has important theoretical significance for disclosing the internal mechanism of the stratum subsidence specificity under the occurrence conditions of the thick surface soil and the thin bedrock, the method is a basic research for subsequently developing the prevention and control of the subsidence area in coal mining and ensuring the safety of buildings (structures) in a near mining area.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. Wherein:
fig. 1 is a schematic representation of the co-initiation of surface subsidence by coal seam mining and hydrophobic consolidation of a bottom aquifer in accordance with an embodiment of the present invention.
FIG. 2 is a schematic representation of a model of surface subsidence induced by hydrophobic consolidation of a bottom aquifer according to one embodiment of the present invention;
FIG. 3 is a schematic representation of a three-dimensional coordinate system of a bottom aquifer-induced surface subsidence induced by hydrophobic consolidation according to an embodiment of the present invention;
fig. 4 is a calculation of a surface subsidence according to one embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. The various examples are provided by way of explanation of the invention, and not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.
As shown in fig. 1 to 4, according to an embodiment of the present invention, there is provided a method for predicting the amount of surface subsidence caused by mining a thick overburden and a thin bedrock. Sequentially from the ground surface to the bottom: the high-soil-density low-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-soil-density high-density; the bottom water-containing layer is a solid-liquid two-phase random medium with solid-phase soil particles and confined water. The multilayer rock-soil body containing and resisting water layer above the bottom water-bearing layer is equivalent to homogeneous rock-soil body, and the saturated pressure-bearing homogeneous rock-soil body is below the homogeneous rock-soil body.
The surface subsidence is jointly initiated by coal seam mining and bottom water-bearing stratum hydrophobic consolidation, wherein the bottom water-bearing stratum belongs to a confined water-bearing stratum, the bottom water-bearing stratum is hydrophobic to form a virtual falling funnel, the whole bottom water-bearing stratum is filled with confined water, the whole bottom water-bearing stratum is subjected to hydrophobic consolidation subsidence within the influence range of the hydrophobic consolidation, and stratum compression initiated by the hydrophobic consolidation within the range of the virtual falling funnel of the bottom water-bearing stratum is regarded as thickening mining.
The contemplated method comprises the steps of:
1) establishing a prediction model of surface subsidence caused by coal mining
Any coal bed unit d xi under the condition of a two-dimensional coordinate system2dη2Mining induced subsidence W of arbitrary point A (x, y) of the earth's surfacece(x) Comprises the following steps:
Figure BDA0002808450920000071
r: the radius of influence of coal seam mining on surface subsidence; d xi2: the horizontal dimension of the coal seam unit; d eta2: the vertical size of the coal seam unit;
extending the two-dimensional coordinates to a three-dimensional coordinate system, if the coal seam is horizontal, the coal seam coordinate system o2、ξ2、
Figure BDA0002808450920000072
The horizontal projection of the horizontal projection is coincident with the o, x and y horizontal projections of the earth surface coordinate system, so that the coal bed unit
Figure BDA0002808450920000073
Is used to induce subsidence W at any point A (x, y) of the earth's surfacece(x, y) is:
Figure BDA0002808450920000074
in the inclined coal seam, the maximum sinking amount of the coal seam roof is W0Then over the entire mining range omega2The subsidence of any point A (x, y) on the earth surface caused by inner mining is as follows:
Figure BDA0002808450920000075
the subsidence of the earth surface caused by coal mining meets the subsidence model of the traditional probability integration method, which can be seen in coal mining subsidence science, Guo growth and the like, page 91, the coal industry Press, 2 nd edition 2016, 7 months. The coal seam mining-induced surface subsidence follows a linear superposition principle, and after the movement is stable, the surface subsidence volume V is caused by the coal seam miningSink 2Equal to coal production volume VCoal miningI.e. VSink 2＝VCoal mining；
The bottom aquifer in the hydrophobic consolidation of the bottom aquifer is a confined aquifer, pores in the bottom aquifer are filled with confined water, the solid-phase soil particles and the confined water in the pores are incompressible and can be regarded as a horizontal homogeneous and isotropic solid-liquid two-phase random medium, and the overlying topsoil layer obeys the random medium theory in the hydrophobic consolidation sinking process of the bottom aquifer;
the bottom aquifer is a semi-infinite space body, namely the compression of soil is carried out under the condition of side limitation, the pore compression caused by hydrophobic consolidation in the bottom aquifer only occurs along the vertical direction, and the compression property of the same kind of soil does not change along with the depth.
2) Establishing a prediction model of surface subsidence caused by hydrophobic consolidation of a bottom aquifer
The subsidence S (x, y, z) of any point of the earth surface caused by hydrophobic consolidation of the bottom aquifer can be determined by a subsidence source function
Figure BDA0002808450920000081
And sink propagation distribution function
Figure BDA0002808450920000082
Expressed as:
Figure BDA0002808450920000083
wherein omega1Is a hydrophobic area of a bottom aquifer;
in step 2), the hydrophobic consolidation of the bottom aquifer is mainly caused by the reduction of the solid-phase soil particle pores due to the increase of the effective stress after the pressure of the confined water (pore water) is reduced. From sink source functions
Figure BDA0002808450920000084
Calculating to obtain the three-dimensional unit of the bottom aquifer
Figure BDA0002808450920000085
The amount of compression set ds due to the hydrophobic effect,
in a two-dimensional coordinate system, the bottom aquifer is located at a depth (H-eta) before being drained1) D xi of plane unit1dη1The effective stress between solid-phase soil particles is sigma, and the following calculation formula is satisfied:
σ＝(H-M)γ0+(M-η1)γf-(h-η1)γwformula 5
Wherein eta is1: the distance from any plane unit in the bottom water-containing layer to the bottom of the bottom water-containing layer; gamma ray0: average bulk density, kN/m, of all the earth above the bottom aquifer3；γf: volume weight of saturated soil body in pressure water in bottom water-bearing stratum, kN/m3；γw: volume weight of pressure-bearing pore water in bottom water-containing layer, kN/m3(ii) a h: the height of an initial water head of each point of the bottom aquifer; h: the thickness of the thick topsoil layer; m: the thickness of the bottom aquifer; d xi1: the horizontal dimension of the planar unit; d eta1: the vertical dimension of the planar unit;
h: the height of the initial water head of each point of the bottom aquifer is based on the water head datum plane at the bottom of the bottom aquifer, and the flow speed water head generated by the flow of underground water is ignored.
The bottom of the bottom aquifer is hydrophobic, the height of the initial water head is reduced by delta H, and as the total stress of the overlying surface soil layer is kept constant, the part with reduced pore water pressure is converted into solid-phase soil particles to bear, so the depth (H-eta) in the bottom aquifer1) D xi plane unit1dη1The effective stress increase of (a) is:
Figure BDA0002808450920000091
the depth (H-eta) can be obtained by the compaction coefficient formula and consolidation formula of the soil1) D xi of plane unit1dη1At effective stress increment
Figure BDA0002808450920000092
The compression deformation ds, ds infinitesimal consolidation compression deformation generated under the action, the compression function of which is the sinking source function of the bottom aquifer plane unit
Figure BDA0002808450920000093
Figure BDA0002808450920000094
Wherein e is0: initial void ratio of the bottom aquifer; cc: compression index of the bottom aquifer. The compaction coefficient formula is
Figure BDA0002808450920000095
The formula of consolidation is
Figure BDA0002808450920000096
In the formula, av: the bottom aquifer compaction factor; e.g. of the type0: initial pore ratio of the bottom aquifer; Δ e: a change in the bottom aquifer porosity ratio;
Figure BDA0002808450920000097
effective stress increment of the bottom aquifer; Δ si: the deformation of the bottom aquifer under a certain level of effective stress increment; Δ ei: change in the void ratio of the bottom aquifer at a certain level of effective stress increment; e.g. of the type0i: the bottom aquifer pore ratio before a certain level of effective stress increment; hi: the bottom hydrous layer thickness before a certain effective stress increment.
According to the random medium theory, the plane unit d xi in the plane problem1dη1The surface subsidence caused by the compression subsidence of the hydrophobic consolidation is the surface subsidence propagation distribution function caused by the hydrophobic consolidation of the bottom aquifer.
In step 2), sink source function is settled according to
Figure BDA0002808450920000098
Calculating to obtain the compression deformation ds generated by the hydrophobic bottom aquifer, and calculating to obtain the surface subsidence caused by the hydrophobic subsidence of the bottom aquifer by the subsidence propagation distribution function, namely:
Figure BDA0002808450920000099
wherein, Wwe(x) Is the amount of surface subsidence, r (eta), caused by the hydrophobic settlement of any plane unit1) Is eta1The main influence range of hydrophobic settlement of a bottom aquifer on the earth surface on the horizontal level;
and after calculating a tiny compression amount, the subsidence propagation distribution function is transferred to the surface, namely, the transfer amount of the subsidence source function to the surface is calculated.
Radius of influence range-R of hydrophobic consolidation of whole bottom aquiferw～+RwInternal, i.e. RwIs the radius of influence of the hydrophobic consolidation of the bottom aquifer, and the hydrophobic consolidation of the planar unit between the top of any bottom aquifer and the bottom of the bottom aquifer generates a tiny volume compression d xi1ds, ultimate subsidence W of the surface due to hydrophobic consolidation of the bottom aquiferw(x) I.e. the plane unit d xi1dη1Superposition of the effects:
Figure BDA0002808450920000101
a two-dimensional coordinate system is expanded into a three-dimensional coordinate system, and a hydrophobic settlement coordinate system xi of a bottom aquifer1、o1、
Figure BDA0002808450920000102
The horizontal projection of the X, O and Y coordinate system coincides with the subsidence W of the X direction of the earth surfacewe(x) And y-direction sinkage Wwe(y) are respectively:
Figure BDA0002808450920000103
then the bottom aquifer eta1A certain three-dimensional unit at the horizontal position
Figure BDA0002808450920000104
The hydrophobic consolidation of (2) induces the subsidence W of any point A (x, y) on the surfacewe(x, y) may be represented as:
Figure BDA0002808450920000105
then at the top of the bottom aquifer, eta1M with the bottom of the bottom hydrous layer, eta1Radius of influence range-R of hydrophobic consolidation of the entire bottom aquifer between-0w～+RwIn that any three-dimensional unit generates a slight volume compression
Figure BDA0002808450920000106
Final subsidence W of earth surface caused by hydrophobic consolidation of bottom aquiferw(x, y) is the superposition of the effects of the above infinitesimal bodies:
Figure BDA0002808450920000107
3) and linearly overlapping the subsidence of the surface subsidence caused by coal mining and hydrophobic consolidation of the bottom aquifer to obtain a prediction model of the subsidence of the surface subsidence caused by mining the thick surface soil and the thin bedrock.
In the step 3) of the process,
the coal seam mining and the bottom water-bearing stratum hydrophobic consolidation both cause surface subsidence, the surface subsidence caused by the coal seam mining and the bottom water-bearing stratum hydrophobic consolidation are independent of each other, and then the final subsidence amount of the surface subsidence can be expressed as the linear superposition result of the surface subsidence caused by the coal seam mining and the surface subsidence caused by the bottom water-bearing stratum hydrophobic consolidation:
W(x,y)＝Wc(x,y)+Ww(x, y) formula 13
Preferably, a preparation step is further included before step 1), the preparation step specifically includes,
drilling and coring the thin bedrock stratum and the thick surface soil layer from the earth surface to determine the thickness H of the thin bedrock1The thickness H of the thick surface soil layer and the thickness M of the bottom water-bearing layer, and carrying out a mechanical test on the cored sample to test the average volume weight gamma of all the stratum soil bodies above the bottom water-bearing layer0And the volume weight gamma of the saturated soil body in the pressure water in the bottom aquiferfBottom aquiferCompression index CcTo initial pore ratio e0；
Monitoring the water level change of a water-bearing stratum at the bottom before and after the coal seam is mined and in the mining process; the water level change of the bottom water-bearing stratum before and after the coal seam is mined and during the mining process can be monitored through the hydrological observation holes close to the similar coal seam or the overlying strata of the similar coal seam in the adjacent mining area.
According to the water level change of the bottom water-bearing stratum, determining the initial water level h before hydrophobic sedimentation of the bottom water-bearing stratum and the stable water level f (xi) after hydrophobic sedimentation of the bottom water-bearing stratum1)；
Calculating a water level drop value according to water level changes at different positions of the water-bearing stratum at the bottom: Δ h ═ h-f (ξ)1)。
In the prediction method for the subsidence amount of the surface subsidence caused by the mining of the thick surface soil and the thin bedrock, the projection of the center of the surface subsidence, the center of the mining of the coal bed and the center of the hydrophobic consolidation of the water-bearing stratum at the bottom are superposed on the surface water plane, a prediction model is established by adopting a unified coordinate system,
the unified coordinate system comprises three coordinate systems of a surface subsidence coordinate system, a coal seam mining coordinate system and a bottom aquifer drainage consolidation coordinate system, the three coordinate systems have the same scale, wherein,
the surface subsidence coordinate system selects a surface point O which is directly above the center of the goaf as an origin of an abscissa axis x, and the direction of the coal seam from the origin along a horizontal plane is taken as the positive direction of the x axis; an arbitrary point subsidence value W (x) with a surface abscissa of x and a horizontal movement value u (x) are respectively vertically downward and vertically upward from an origin O;
the coordinate origin of the bottom aquifer hydrophobic consolidation coordinate system is positioned at the bottom O of the bottom aquifer right above the midpoint of the bottom plate of the run-to goaf1On the abscissa xi1The same direction as the x-axis, the ordinate η1Vertically upwards;
the origin of coordinates of a coal seam mining coordinate system is in the middle point O of the bottom plate of the run-out goaf2On the abscissa xi2The same direction as the x-axis, the ordinate η2Vertically upwards.
Examples
According to the prediction method of the surface subsidence caused by the mining of the thick surface soil and the thin bedrock, the following methods are known: the average thickness of the coal seam is 2.5m, the mining depth of the coal seam is 800m, and the thickness H of the thin bedrock1200M, the thickness of the overlying thick surface soil layer is H-600M, the thickness of the bottom water-containing layer is M-80M, and the influence radius R of hydrophobic consolidationw1000m, and a working face length L of 200 m. The coal seam average thickness and the working face trend length are combined to form the mining range omega of the coal seam2Namely the coal seam mining range.
The water level before the bottom aquifer is drained is-300 m, the water head of the bottom aquifer is reduced by 50m due to drainage, H is H (600) -300, the-300 is the distance from the water head of the bottom aquifer to the ground surface, and the negative sign represents that the water head is lower than the ground surface. Compression index CcInitial void ratio e of 0.400.6, average bulk density gamma of all the earth above the bottom aquifer0＝18kN/m3Volume weight gamma of saturated soil body in pore water in bottom aquiferf＝20kN/m3Volume weight of pore water in bottom aquifer gammaw＝9.81kN/m3。
And solving the steps in sequence to obtain the predicted results of the surface subsidence under the geological mining condition and the hydrophobic bottom, as shown in figure 4.
When the coal seam mining effect is considered independently, the maximum value of the subsidence of the surface subsidence is 1.416m, and the subsidence of the surface subsidence ranges from minus 440m to 440m in the radius range of 10 mm; when the coal seam mining and the hydrophobic consolidation of the bottom aquifer are considered to act together, the maximum value of the subsidence of the surface subsidence is 2.537m, and the radius range of the subsidence of the surface subsidence being 10mm is-1340 m. Analysis shows that the maximum value of the surface subsidence under the combined action of coal seam mining and bottom aquifer hydrophobic consolidation is far larger than the maximum value of the surface subsidence under the coal seam mining action, the surface subsidence coefficient under the combined action is larger than 1, and the range of the surface subsidence under the combined action of 10mm is obviously larger than the range of the surface subsidence under the traditional surface subsidence theory under the coal seam mining action.
Analysis shows that the surface subsidence coefficient of the thick surface soil and the thin bedrock is obviously increased at the moment, the surface subsidence range is far extended relative to a mining area, and the establishment of the prediction model of the surface subsidence amount in the mining of the thick surface soil and the thin bedrock reveals the internal mechanism of the stratum subsidence particularity under the occurrence condition of the thick surface soil and the thin bedrock, so that the basic research of preventing and controlling the subsidence area in the coal mining and ensuring the safety of buildings (structures) in the near mining area is carried out subsequently.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
the method for predicting the surface subsidence caused by mining the thick surface soil and the thin bedrock is based on the geological mining characteristics of the thick surface soil and the thin bedrock and the characteristics of various media and multi-field coupling action, takes the water-soil coupling action generated by the thick surface soil layer influenced by coal mining activities into the stratum subsidence deformation, obtains the surface subsidence expression when the bottom aquifer is subjected to hydrophobic settlement through solving the subsidence source function and the subsidence propagation distribution function, further establishes the thick surface soil and the thin bedrock mining subsidence prediction model and the prediction method thereof, fills the blank that the surface subsidence prediction model and the prediction method which are jointly caused by the coal mining and the water-hydrophobic settlement of the confined pore of the bottom aquifer under the geological mining conditions of the thick surface soil and the thin bedrock are not considered at present, and has important theoretical significance for disclosing the internal mechanism of the stratum subsidence specificity under the occurrence conditions of the thick surface soil and the thin bedrock, the method is a basic research for subsequently developing the prevention and control of the subsidence area in coal mining and ensuring the safety of buildings (structures) in a near mining area.
The above is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1.一种厚表土薄基岩开采引发地表沉陷下沉量的预计方法，其特征在于，1. a kind of prediction method of surface subsidence subsidence amount caused by mining of thick topsoil and thin bedrock, is characterized in that, 由地表至下依次为：厚表土层、薄基岩层和煤层，所述厚表土层的上表面为所述地表、所述厚表土层的下部为底部含水层、所述地表与所述底部含水层之间为上覆表土层；所述底部含水层内为具有固相土粒和承压水的固液两相随机介质；From the surface to the bottom are: thick topsoil layer, thin bedrock layer and coal layer, the upper surface of the thick topsoil layer is the surface, the lower part of the thick topsoil layer is the bottom aquifer, the surface and the bottom water-bearing layer Between the layers is the overlying topsoil layer; the bottom aquifer is a solid-liquid two-phase random medium with solid-phase soil particles and confined water; 所述厚表土薄基岩地表沉陷下沉量由煤层开采和底部含水层疏水固结共同引发，其中，The surface subsidence of the thick topsoil and thin bedrock is caused by coal seam mining and hydrophobic consolidation of the bottom aquifer, wherein, 所述预计方法包括如下步骤：The predicting method includes the following steps: 1)建立煤层开采引发地表沉陷的预计模型1) Establish a prediction model for surface subsidence caused by coal seam mining 在二维坐标系情况下任一煤层单元dξ2dη2开采引发地表任意点A(x,y)的下沉量Wce(x)为：In the case of a two-dimensional coordinate system, the subsidence amount W ce (x) of any point A(x, y) on the surface caused by the mining of any coal seam unit dξ 2 dη 2 is:
Figure FDA0003156929100000011
Figure FDA0003156929100000011
 r：煤层开采对地表沉陷的影响半径；dξ2：所述煤层单元的水平尺寸；dη2：所述煤层单元的竖向尺寸；r: influence radius of coal seam mining on surface subsidence; dξ 2 : horizontal size of the coal seam unit; dη 2 : vertical size of the coal seam unit; 将所述二维坐标扩展为三维坐标系统，若煤层是水平的，煤层坐标系o2、ξ2、
Figure FDA0003156929100000016
和地表坐标系o、x、y水平投影重合，则煤层单元
Figure FDA0003156929100000017
的开采引发地表任意点A(x,y)的下沉量Wce(x,y)为：Extending the two-dimensional coordinates into a three-dimensional coordinate system, if the coal seam is horizontal, the coal seam coordinate systems o 2 , ξ 2 ,
Figure FDA0003156929100000016
Coinciding with the horizontal projection of the surface coordinate system o, x, and y, the coal seam unit
Figure FDA0003156929100000017
The subsidence amount W ce (x, y) of any point A (x, y) on the surface caused by mining is:
Figure FDA0003156929100000012
Figure FDA0003156929100000012
 在倾斜煤层中，煤层顶板的最大下沉量为W0，则在整个开采范围Ω2内采煤引发地表任意点A(x,y)点的下沉量为：In the inclined coal seam, the maximum subsidence amount of the coal seam roof is W 0 , then the subsidence amount of any point A(x,y) on the surface caused by coal mining in the entire mining range Ω 2 is:
Figure FDA0003156929100000013
Figure FDA0003156929100000013
 2)建立底部含水层疏水固结引发地表沉陷的预计模型2) Establish a prediction model for surface subsidence caused by hydrophobic consolidation of the bottom aquifer 所述底部含水层疏水固结引发的地表任意点的下沉量S(x,y,z)可由下沉源函数
Figure FDA0003156929100000014
和下沉传播分布函数
Figure FDA0003156929100000015
表示为：The subsidence amount S(x, y, z) at any point on the surface caused by the hydrophobic consolidation of the bottom aquifer can be determined by the subsidence source function
Figure FDA0003156929100000014
and the sinking propagation distribution function
Figure FDA0003156929100000015
Expressed as:
Figure FDA0003156929100000021
Figure FDA0003156929100000021
 其中，Ω1为底部含水层疏水区域；η1：底部含水层内任一平面单元到底部含水层底部的距离；底部含水层疏水沉降坐标系ξ1、o1、
Figure FDA0003156929100000022
Among them, Ω 1 is the hydrophobic area of the bottom aquifer; η 1 : the distance from any plane unit in the bottom aquifer to the bottom of the bottom aquifer; the hydrophobic settlement coordinate system of the bottom aquifer ξ 1 , o 1 ,
Figure FDA0003156929100000022
 由土的压密系数公式和固结公式，可得位于深度(H-η1)处的平面单元dξ1dη1在有效应力增量
Figure FDA0003156929100000023
作用下产生的压缩变形量ds，其压缩量函数即为底部含水层平面单元的所述下沉源函数
Figure FDA0003156929100000024
From the compaction coefficient formula and consolidation formula of soil, we can obtain the effective stress increment of the plane element dξ 1 dη 1 located at the depth (H-η 1 )
Figure FDA0003156929100000023
The compressive deformation ds produced under the action, its compressive function is the subsidence source function of the bottom aquifer plane unit
Figure FDA0003156929100000024
Figure FDA0003156929100000025
Figure FDA0003156929100000025
 其中，e0：所述底部含水层的初始孔隙比；Cc：所述底部含水层的压缩指数；Wherein, e 0 : the initial void ratio of the bottom aquifer; C c : the compressibility index of the bottom aquifer; 根据将所述下沉源函数
Figure FDA0003156929100000026
计算得到底部含水层疏水产生的压缩变形量ds，由所述下沉传播分布函数计算得到所述底部含水层疏水沉降引发的地表下沉量，即：According to the sinking source function
Figure FDA0003156929100000026
The compressive deformation ds caused by the hydrophobicity of the bottom aquifer is calculated, and the surface subsidence caused by the hydrophobic settlement of the bottom aquifer is calculated from the subsidence propagation distribution function, namely:
Figure FDA0003156929100000027
Figure FDA0003156929100000027
 其中，Wwe(x)是任一平面单元疏水沉降引发的地表下沉量，r(η1)为η1水平上所述底部含水层疏水沉降对地表的主要影响范围；Wherein, W we (x) is the amount of surface subsidence caused by hydrophobic subsidence of any plane unit, and r (η 1 ) is the main influence range of the hydrophobic subsidence of the bottom aquifer on the surface at the level of η 1 ; 3)将所述煤层开采和所述底部含水层疏水固结引发的地表沉陷的下沉量进行线性叠加以获得所述厚表土薄基岩开采引发地表沉陷下沉量的预计模型。3) Linearly superimposing the subsidence amount of the surface subsidence caused by the hydrophobic consolidation of the coal seam mining and the bottom aquifer to obtain a predicted model of the surface subsidence subsidence amount caused by the mining of the thick topsoil and thin bedrock. 2.根据权利要求1所述的预计方法，其特征在于，2. The prediction method according to claim 1, characterized in that, 在所述步骤2)中，由所述下沉源函数
Figure FDA0003156929100000028
计算得到底部含水层三维单元
Figure FDA0003156929100000029
疏水产生的压缩变形量ds，In the step 2), by the sinking source function
Figure FDA0003156929100000028
Calculated 3D unit of bottom aquifer
Figure FDA0003156929100000029
The compressive deformation ds caused by hydrophobicity, 在二维坐标系中，底部含水层疏水前位于深度(H-η1)处的平面单元dξ1dη1固相土粒间的有效应力为σ满足如下计算公式：In the two-dimensional coordinate system, the effective stress between the solid phase soil particles of the plane element dξ 1 dη 1 at the depth (H-η 1 ) before the bottom aquifer is hydrophobic is σ, which satisfies the following formula: σ＝(H-M)γ0+(M-η1)γf-(h-η1)γw 式5σ=(HM)γ 0 +(M-η 1 )γ f -(h-η 1 )γ w Equation 5 其中，η1：底部含水层内任一平面单元到底部含水层底部的距离；γ0：底部含水层以上所有地层土体的平均容重，kN/m3；γf：底部含水层内承压水中饱和土体的容重，kN/m3；γw：底部含水层内承压孔隙水的容重，kN/m3；h：底部含水层各点初始水头的高度；H：所述厚表土层的厚度；M：所述底部含水层的厚度；dξ1：所述平面单元的水平尺寸；dη1：所述平面单元的竖向尺寸；Among them, η 1 : the distance from any plane unit in the bottom aquifer to the bottom of the bottom aquifer; γ 0 : the average bulk density of all strata above the bottom aquifer, kN/m 3 ; γ f : the confined pressure in the bottom aquifer Bulk density of soil saturated in water, kN/m 3 ; γ w : bulk density of confined pore water in bottom aquifer, kN/m 3 ; h: height of initial water head at each point of bottom aquifer; H: the thick topsoil layer M: the thickness of the bottom aquifer; dξ 1 : the horizontal dimension of the plane unit; dη 1 : the vertical dimension of the plane unit; 底部含水层的底部发生疏水，初始水头的高度下降Δh，由于上覆表土层的总应力保持恒定，孔隙水压力降低的部分转化为由固相土粒承担，故底部含水层内深度(H-η1)处平面单元dξ1dη1的有效应力增加为：The bottom of the bottom aquifer is hydrophobic, and the height of the initial water head decreases by Δh. Since the total stress of the overlying topsoil remains constant, the part of the reduced pore water pressure is converted into the solid phase soil particles, so the depth of the bottom aquifer (H- The effective stress increase of the planar element dξ 1 dη 1 at η 1 ) is:
Figure FDA0003156929100000031
Figure FDA0003156929100000031
 3.根据权利要求2所述的预计方法，其特征在于，3. The prediction method according to claim 2, characterized in that, 在所述步骤2)中，In the step 2), 在整个所述底部含水层疏水固结影响的半径范围-Rw～+Rw内，任何平面单元疏水固结均产生微小体积压缩dξ1ds，地表由于底部含水层疏水固结引发的最终下沉量Ww(x)即为平面单元dξ1dη1影响的叠加：Within the radius range -R w ~ +R w affected by the hydrophobic consolidation of the entire bottom aquifer, the hydrophobic consolidation of any plane unit will produce a tiny volumetric compression dξ 1 ds, and the surface will eventually collapse due to the hydrophobic consolidation of the bottom aquifer. The weight W w (x) is the superposition of the effects of the plane element dξ 1 dη 1 :
Figure FDA0003156929100000032
Figure FDA0003156929100000032
 将所述二维坐标系统扩展为三维坐标系统，底部含水层疏水沉降坐标系ξ1、o1、
Figure FDA0003156929100000033
和地表下沉坐标系x、o、y水平投影重合，则地表x方向的下沉Wwe(x)和y方向下沉量Wwe(y)分别为：Extending the two-dimensional coordinate system into a three-dimensional coordinate system, the bottom aquifer hydrophobic settlement coordinate system ξ 1 , o 1 ,
Figure FDA0003156929100000033
Coinciding with the horizontal projection of the surface subsidence coordinate system x, o, and y, the surface subsidence W we (x) in the x direction and the subsidence amount W we (y) in the y direction are respectively:
Figure FDA0003156929100000034
Figure FDA0003156929100000034
 则底部含水层η1水平处某一三维单元
Figure FDA0003156929100000035
的疏水固结引发所述地表任意点A(x,y)的下沉量Wwe(x,y)可表示为：Then a three-dimensional unit at the level of η 1 of the bottom aquifer
Figure FDA0003156929100000035
The subsidence amount W we (x, y) of any point A(x, y) on the surface caused by the hydrophobic consolidation can be expressed as:
Figure FDA0003156929100000036
Figure FDA0003156929100000036
 则在底部含水层顶部、η1＝M与底部含水层底部、η1＝0之间的整个底部含水层疏水固结影响的半径范围-Rw～+Rw内，任何三维单元均产生微小体积压缩
Figure FDA0003156929100000037
地表因底部含水层疏水固结引发的最终下沉量Ww(x,y)即为微元体影响的叠加：Then in the radius range -R w ~ +R w of the hydrophobic consolidation effect of the whole bottom aquifer between the top of the bottom aquifer, η 1 =M and the bottom of the bottom aquifer, η 1 =0, any three-dimensional unit will produce tiny volume compression
Figure FDA0003156929100000037
The final subsidence amount W w (x, y) of the surface caused by the hydrophobic consolidation of the bottom aquifer is the superposition of the influence of micro-elements:
Figure FDA0003156929100000041
Figure FDA0003156929100000041
 4.根据权利要求3所述的预计方法，其特征在于，4. The prediction method according to claim 3, characterized in that, 在所述步骤3)中，In the step 3), 所述煤层开采和所述底部含水层疏水固结均将引发地表沉陷，所述煤层开采和所述底部含水层疏水固结引发的地表沉陷相互独立，则地表沉陷的最终下沉量可表示为所述煤层开采引发的地表沉陷和所述底部含水层疏水固结引发的地表沉陷线性叠加的结果：Both the coal seam mining and the hydrophobic consolidation of the bottom aquifer will cause surface subsidence, and the surface subsidence caused by the coal seam mining and the hydrophobic consolidation of the bottom aquifer are independent of each other, so the final subsidence amount of the surface subsidence can be expressed as The result of linear superposition of the surface subsidence caused by the mining of the coal seam and the surface subsidence caused by the hydrophobic consolidation of the bottom aquifer: W(x,y)＝Wc(x,y)+Ww(x,y) 式13。W(x, y )=Wc(x,y)+ Ww (x,y) Equation 13. 5.根据权利要求1所述的预计方法，其特征在于，5. The prediction method of claim 1, wherein: 在所述步骤1)之前还包括准备步骤，所述准备步骤具体包括，Before the step 1), a preparation step is also included, and the preparation step specifically includes, 由所述地表对薄基岩层和厚表土层进行钻孔取芯，确定所述薄基岩的厚度H1、所述厚表土层的厚度H和所述底部含水层的厚度M并对取芯的试样开展力学试验，测试底部含水层以上所有地层土体的平均容重γ0和底部含水层内承压水中饱和土体的容重γf、所述底部含水层的压缩指数Cc与初始孔隙比e0；The thin bedrock layer and the thick topsoil layer are drilled and cored from the surface, the thickness H 1 of the thin bedrock, the thickness H of the thick topsoil layer and the thickness M of the bottom aquifer are determined and the core is taken The mechanical test was carried out on the samples of the bottom aquifer to test the average bulk density γ 0 of all strata above the bottom aquifer, the bulk density γ f of the soil saturated in confined water in the bottom aquifer, the compression index C c of the bottom aquifer and the initial porosity than e 0 ; 监测煤层开采前后及其开采过程中所述底部含水地层的水位变化；Monitoring the water level changes of the bottom water-bearing formation before and after the mining of the coal seam and during the mining process; 根据所述底部含水地层的水位变化，确定所述底部含水地层疏水沉降前的初始水位h以及所述底部含地层疏水沉降后的稳定水位f(ξ1)；According to the water level change of the bottom water-bearing formation, determine the initial water level h before the hydrophobic settlement of the bottom water-bearing formation and the stable water level f(ξ 1 ) after the hydrophobic settlement of the bottom water-bearing formation; 根据所述底部含水地层不同位置处的水位变化计算水位下降值：Δh＝h-f(ξ1)。The water level drop value is calculated according to the water level changes at different positions of the bottom water-bearing formation: Δh=hf(ξ 1 ). 6.根据权利要求1所述的预计方法，其特征在于，6. The prediction method of claim 1, wherein: 所述地表沉陷的中心、所述煤层开采的中心以及底部含水层疏水固结的中心在地表水平面投影重合，采用统一坐标系建立预计模型，The center of the surface subsidence, the center of the coal seam mining, and the center of the hydrophobic consolidation of the bottom aquifer overlap on the surface level, and a unified coordinate system is used to establish a prediction model, 所述统一坐标系包括地表沉陷坐标系、煤层开采坐标系和底部含水层疏水固结坐标系共三个坐标系，上述三个坐标系的比例尺相同，其中，The unified coordinate system includes three coordinate systems: the surface subsidence coordinate system, the coal seam mining coordinate system and the bottom aquifer hydrophobic consolidation coordinate system, and the scales of the three coordinate systems are the same, wherein, 所述地表沉陷坐标系选择走向采空区中央正上方的地表点O作为横坐标轴x的原点，由原点沿水平面指向煤层走向方向为x轴正向；地表横坐标为x的任意点下沉值W(x)和水平移动值u(x)分别由原点O竖直向下和竖直向上；The surface subsidence coordinate system selects the surface point O directly above the center of the goaf as the origin of the abscissa axis x, and the direction from the origin to the coal seam along the horizontal plane is the positive direction of the x-axis; the surface abscissa is the subsidence of any point of x The value W(x) and the horizontal movement value u(x) are vertically downward and vertically upward from the origin O, respectively; 所述底部含水层疏水固结底部含水层疏水固结坐标系的坐标原点在走向采空区底板中点正上方的底部含水层的底部O1，横坐标ξ1与x轴方向相同，纵坐标η1竖直向上；Hydrophobic consolidation of the bottom aquifer The coordinate origin of the hydrophobic consolidation coordinate system of the bottom aquifer is at the bottom O 1 of the bottom aquifer just above the midpoint of the floor of the goaf. The abscissa ξ 1 is in the same direction as the x-axis, and the ordinate η 1 is vertically upward; 所述煤层开采坐标系的坐标原点在走向采空区底板中点O2，横坐标ξ2与x轴方向相同，纵坐标η2竖直向上。The coordinate origin of the coal seam mining coordinate system is at the midpoint O 2 of the floor going to the gob, the abscissa ξ 2 is in the same direction as the x-axis, and the ordinate η 2 is vertically upward. 7.根据权利要求1所述的预计方法，其特征在于，7. The prediction method of claim 1, wherein: 所述煤层开采引发的地表沉陷满足传统概率积分法沉陷模型，遵循线性叠加原理，移动稳定后由于煤层开采引发的地表下沉体积V下沉2等于煤采出体积V采煤，即V下沉2＝V采煤；The surface subsidence caused by coal seam mining satisfies the traditional probability integral method subsidence model and follows the principle of linear superposition. After the movement is stabilized, the surface subsidence volume V subsidence 2 caused by coal seam mining is equal to the coal mining volume V coal mining , that is, V subsidence 2 = V coal mining ; 所述底部含水层疏水固结中的底部含水层为承压含水地层，所述底部含水层中的孔隙被承压水充满、固相土粒和孔隙内的承压水不可压缩，可视为水平均质、各向同性的固液两相随机介质，所述上覆表土层在所述底部含水层疏水固结下沉过程中服从随机介质理论；The bottom aquifer in the hydrophobic consolidation of the bottom aquifer is a confined aquifer, the pores in the bottom aquifer are filled with confined water, and the solid phase soil particles and confined water in the pores are incompressible, which can be regarded as A horizontally homogeneous, isotropic solid-liquid two-phase random medium, the overlying topsoil obeys the random medium theory during the hydrophobic consolidation and subsidence of the bottom aquifer; 所述底部含水层为半无限空间体，底部含水层疏水固结造成的孔隙压缩仅沿竖向发生，同类土的压缩性质不随深度而变化。The bottom aquifer is a semi-infinite space body, the pore compression caused by the hydrophobic consolidation of the bottom aquifer only occurs vertically, and the compression properties of similar soils do not change with depth. 8.根据权利要求1所述的预计方法，其特征在于，8. The prediction method of claim 1, wherein: 所述底部含水层属于承压含水层，所述底部含水层疏水形成虚拟降落漏斗，整个所述底部含水层还充满承压水，在疏水固结的影响范围内整个底部含水层均发生疏水固结沉陷，The bottom aquifer is a confined aquifer, the bottom aquifer is hydrophobic to form a virtual falling funnel, the entire bottom aquifer is also filled with confined water, and hydrophobic solidification occurs in the entire bottom aquifer within the influence of hydrophobic consolidation. knot sinking, 将底部含水层的虚拟降落漏斗范围内疏水固结引发的地层压缩看作变厚开采。The formation compression caused by hydrophobic consolidation within the virtual falling funnel of the bottom aquifer is regarded as thickening production.
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